Green Synthesis of Silver Nanoparticles Using *Heterotheca inuloides* and Its Antimicrobial Activity in Catgut Suture Threads

*Saraí C. Guadarrama-Reyes, Raúl A. Morales-Luckie, Víctor Sánchez-Mendieta, María G. González-Pedroza, Edith Lara-Carrillo, Ulises Velazquez-Enriquez, Victor Toral-Rizo and Rogelio Scougall-Vilchis*

#### **Abstract**

Silver nanoparticles were synthesized through a green method, using *Heterotheca inuloides* as a bioreducing agent. Moreover, catgut suture threads were decorated with those biogenic silver nanoparticles, and their antibacterial activity versus highly resistant pathogenic microorganisms was evaluated. The principles of green chemistry and nanotechnology allow us to obtain advanced materials, such as suture threads, which can reduce or avoid the prevalence of infectious processes in the medical field. Mexican medicinal plants, such as *H. inuloides*, represent an adequate alternative for biosynthesis; this plant species is known for its medicinal benefits and its antibacterial activity, and for that reason, it is being used in folk medicine.

**Keywords:** *Heterotheca inuloides*, green synthesis, silver nanoparticles, antimicrobial activity, catgut, suture

#### **1. Introduction**

Diverse green synthesis methods, involving the use of plant extracts as reducing agents, provide attractive approaches to synthesize AgNPs.

Mexican medicinal plants represent an adequate alternative for biosynthesis, such is the case of *Heterotheca inuloides*, a plant known for its medicinal benefits, as well as anti-inflammatory and analgesic properties. The plant, commonly named as Mexican arnica has been traditionally used for its antimicrobial activity, antifungal, cytotoxic and antioxidative properties, leading the World Health Organization (WHO) to recognize its use in medicine. This species has also been used to treat dental diseases and gastrointestinal disorders [1–6].

The wide use of *H. inuloides*, in medicine, can be attributed to its more than 140 components. Several constituents of the aqueous extract obtained from the dried

flowers have been identified and characterized as antibacterial agents. Flavonoids, sesquiterpenoids, triterpenoids, and sterols are mainly present on its chemical composition [7–9].

Conventional approaches in nano-synthesis involve the use of highly toxic chemicals, resulting in side effects after administration [10, 11]. For this reason, it is of utmost importance for biomedical science to try to minimize any consequent risk to human health.

In modern surgery, attempts have been made to reduce the prevalence of infections related with surgical sutures, through the use of coated materials [12]. Nevertheless, the risk of surgical site infection is a constant challenge in wound closure. By using sutures with an antibacterial coating, the risk of infection is considerably reduced. The significant feature of silver is its broad antimicrobial spectrum associated with biomaterial-related infections [11, 13].

We present a total green synthetic method where *Heterotheca inuloides* is used for the first time to decorate catgut, a suture thread widely used in surgery. Its characterization, and antimicrobial activity against *Staphylococcus aureus* and *Escherichia coli*, is reported.

#### **2. Experimental**

#### **2.1 Synthesis of AgNPs**

The plant material was collected from surrounding fields of the State of Mexico, and it was cleaned using tap water followed by distilled water. *H. inuloides* leaves were dried and finely ground to a powder and then kept at room temperature for 24 h. About 1 gram of powder was poured in 100 mL of distilled water and boiled. The solution was filtered using filter paper. A 10 mM silver nitrate solution (AgNO3, Sigma-Aldrich) was prepared to generate AgNPs; both solutions were mixed in a 1:2.5 ratio.

After 6 h, catgut (USP 3-0, Atramat®) was totally immersed in the solution for 1 h and then taken out and dried at room temperature.

#### **2.2 Characterization of AgNPs**

#### *2.2.1 Spectrophotometry by UV: Vis*

UV-Vis was performed every hour for the next 6 h. Spectral measurements were recorded on a Cary 5000 UV-Vis-NIR Scanning Spectrophotometer using a quartz cell, and the wavelength ranges from 300 to 600 nm.

#### *2.2.2 Spectrophotometry by FTIR*

The FTIR analysis was performed (Bruker, Model 27) to identify the main functional groups in the aqueous extract of *Heterotheca inuloides*.

#### *2.2.3 Scanning electron microscopy (SEM)*

Catgut samples were prepared for its analysis in a JSM-6510-LV microscope (JEOL Tokyo, Japan) at 20 kV of acceleration and using secondary electrons.

The samples were coated with a thin film of gold (c.a. 20 nm) using a Denton Vacuum DESK IV sputtering equipment.

**5**

**Figure 1.**

*Green Synthesis of Silver Nanoparticles Using* Heterotheca inuloides *and Its Antimicrobial…*

Transmission electron microscope (TEM, JEOL JEM-2100, Tokyo, Japan) was used. To evaluate shape and size of silver nanoparticles, the solution was analyzed by placing a drop on a copper grid (300 mesh) coated with carbon film and let to dry at room temperature. A 200 kiloelectronvolt accelerating voltage was used in

The antibacterial activity of AgNPs was determined by well diffusion method against the *Staphylococcus aureus* and *Escherichia coli* on the Mueller-Hinton agar

Catgut suture threads were cut into pieces of approximately 10 mm of length and put on the Petri dishes. Each plate was prepared in triplicate. The plates were

After incubation, a clear zone appeared, and by measuring the halo of inhibition

AgNPs synthesized by *Heterotheca inuloides* produced polydisperse and stable nanoparticles as shown in **Figure 1**. The increase in the intensity of surface plasmonic resonance, at 451 nm, as a function of time, is observed. In addition, it is

By means of transmission electron microscopy (TEM), the size and shape of AgNPs are demonstrated; an average nanoparticle size of 16.0 nm and a standard

confirmed that at 6 h, the formation of the nanoparticles is finished.

*UV-Vis spectra showing that the AgNP plasmon wavelength lies between 440 and 460 nm.*

*DOI: http://dx.doi.org/10.5772/intechopen.89344*

bright-field mode and high resolution.

incubated at 37°C in a Felisa® incubator for 24–48 h.

for both strains, the antibacterial effect was assessed.

**2.3 Antibacterial activity**

plates.

**3. Results**

**3.1 UV-Vis spectroscopy**

*2.2.4 Transmission electron microscopy (TEM)*

*Green Synthesis of Silver Nanoparticles Using* Heterotheca inuloides *and Its Antimicrobial… DOI: http://dx.doi.org/10.5772/intechopen.89344*

#### *2.2.4 Transmission electron microscopy (TEM)*

Transmission electron microscope (TEM, JEOL JEM-2100, Tokyo, Japan) was used. To evaluate shape and size of silver nanoparticles, the solution was analyzed by placing a drop on a copper grid (300 mesh) coated with carbon film and let to dry at room temperature. A 200 kiloelectronvolt accelerating voltage was used in bright-field mode and high resolution.

#### **2.3 Antibacterial activity**

The antibacterial activity of AgNPs was determined by well diffusion method against the *Staphylococcus aureus* and *Escherichia coli* on the Mueller-Hinton agar plates.

Catgut suture threads were cut into pieces of approximately 10 mm of length and put on the Petri dishes. Each plate was prepared in triplicate. The plates were incubated at 37°C in a Felisa® incubator for 24–48 h.

After incubation, a clear zone appeared, and by measuring the halo of inhibition for both strains, the antibacterial effect was assessed.

#### **3. Results**

*Engineered Nanomaterials - Health and Safety*

composition [7–9].

to human health.

*coli*, is reported.

**2. Experimental**

1:2.5 ratio.

**2.1 Synthesis of AgNPs**

**2.2 Characterization of AgNPs**

*2.2.1 Spectrophotometry by UV: Vis*

*2.2.2 Spectrophotometry by FTIR*

*2.2.3 Scanning electron microscopy (SEM)*

Vacuum DESK IV sputtering equipment.

flowers have been identified and characterized as antibacterial agents. Flavonoids, sesquiterpenoids, triterpenoids, and sterols are mainly present on its chemical

Conventional approaches in nano-synthesis involve the use of highly toxic chemicals, resulting in side effects after administration [10, 11]. For this reason, it is of utmost importance for biomedical science to try to minimize any consequent risk

In modern surgery, attempts have been made to reduce the prevalence of infections related with surgical sutures, through the use of coated materials [12]. Nevertheless, the risk of surgical site infection is a constant challenge in wound closure. By using sutures with an antibacterial coating, the risk of infection is considerably reduced. The significant feature of silver is its broad antimicrobial

We present a total green synthetic method where *Heterotheca inuloides* is used for the first time to decorate catgut, a suture thread widely used in surgery. Its characterization, and antimicrobial activity against *Staphylococcus aureus* and *Escherichia* 

The plant material was collected from surrounding fields of the State of Mexico, and it was cleaned using tap water followed by distilled water. *H. inuloides* leaves were dried and finely ground to a powder and then kept at room temperature for 24 h. About 1 gram of powder was poured in 100 mL of distilled water and boiled. The solution was filtered using filter paper. A 10 mM silver nitrate solution (AgNO3, Sigma-Aldrich) was prepared to generate AgNPs; both solutions were mixed in a

After 6 h, catgut (USP 3-0, Atramat®) was totally immersed in the solution for

UV-Vis was performed every hour for the next 6 h. Spectral measurements were recorded on a Cary 5000 UV-Vis-NIR Scanning Spectrophotometer using a quartz

The FTIR analysis was performed (Bruker, Model 27) to identify the main

Catgut samples were prepared for its analysis in a JSM-6510-LV microscope (JEOL Tokyo, Japan) at 20 kV of acceleration and using secondary electrons.

The samples were coated with a thin film of gold (c.a. 20 nm) using a Denton

spectrum associated with biomaterial-related infections [11, 13].

1 h and then taken out and dried at room temperature.

cell, and the wavelength ranges from 300 to 600 nm.

functional groups in the aqueous extract of *Heterotheca inuloides*.

**4**

#### **3.1 UV-Vis spectroscopy**

AgNPs synthesized by *Heterotheca inuloides* produced polydisperse and stable nanoparticles as shown in **Figure 1**. The increase in the intensity of surface plasmonic resonance, at 451 nm, as a function of time, is observed. In addition, it is confirmed that at 6 h, the formation of the nanoparticles is finished.

By means of transmission electron microscopy (TEM), the size and shape of AgNPs are demonstrated; an average nanoparticle size of 16.0 nm and a standard

**Figure 1.** *UV-Vis spectra showing that the AgNP plasmon wavelength lies between 440 and 460 nm.*

#### **Figure 2.**

*TEM images show the size distribution and a spherical shape of AgNPs synthesized by the green reducing agent, having a mean diameter of approximately 17 nm.*

deviation of 1.2 nm are recognized; in addition, an interplanar distance of 0.149 nm, corresponding to plane (220 nm), was found (**Figure 2**).

Scanning electron microscopy images of catgut embedded with AgNPs (reduced with *Heterotheca inuloides*) at different magnifications are shown in **Figure 3**. Ag nanoparticles of spherical in shape are observed distributed over the fiber surface.

#### **4. Characterization of bioreducing agent of AgNp by infrared spectroscopy**

*H. inuloides* represents a source of chemical compounds with variable structural patterns. Several different types of compounds such as sesquiterpenes, triterpenes, polyphenols, and phytosterols have been isolated from essential oil and organic extracts from various parts, including roots, aerial parts, and flowers. According to the abovementioned, the following characteristic functional groups, 3268 cm<sup>−</sup><sup>1</sup> (–OH), 2942 cm<sup>−</sup><sup>1</sup> (c (sp2)–H), 1584 cm<sup>−</sup><sup>1</sup> (C = O), 1393 cm<sup>−</sup><sup>1</sup> (–CH2), 1258 cm<sup>−</sup><sup>1</sup> (–CH3), 1033 cm<sup>−</sup><sup>1</sup> (CO), and 595 cm<sup>−</sup><sup>1</sup> (CH), were detected (**Figure 4**).

The antimicrobial activity of the infusion using *Heterotheca inuloides* as reducing agent, against *Staphylococcus aureus*, can be seen in **Figure 5**. A well-defined inhibition halo around the disk impregnated with the nanoparticles solution is visible.

**7**

**Figure 4.**

**Figure 3.**

*Green Synthesis of Silver Nanoparticles Using* Heterotheca inuloides *and Its Antimicrobial…*

In **Figure 6**, the antimicrobial activity of catgut against *S. aureus* and *E. coli* is observed. The suture threads were cut into small pieces and put on the Petri dishes.

*SEM micrographs showing the catgut suture threads coated with AgNPs synthesized by the green reducing agent. (A) Images revealed that AgNPs were formed on the surface. (B) The micrograph shows a plain catgut suture.*

**Table 1** shows that the use of *Heterotheca inuloides* to synthesize AgNPs produces an antibacterial effect against both strains, by testing disks. The growth inhibition

The inhibition zone for both strains is presented in the next tables.

Some suture thread samples were used as blank.

*FTIR spectrum of the* Heterotheca inuloides *aqueous extract.*

*DOI: http://dx.doi.org/10.5772/intechopen.89344*

*Green Synthesis of Silver Nanoparticles Using* Heterotheca inuloides *and Its Antimicrobial… DOI: http://dx.doi.org/10.5772/intechopen.89344*

#### **Figure 3.**

*Engineered Nanomaterials - Health and Safety*

deviation of 1.2 nm are recognized; in addition, an interplanar distance of 0.149 nm, corresponding to plane (220 nm), was found (**Figure 2**).

**4. Characterization of bioreducing agent of AgNp by infrared** 

(c (sp2)–H), 1584 cm<sup>−</sup><sup>1</sup>

(CO), and 595 cm<sup>−</sup><sup>1</sup>

Scanning electron microscopy images of catgut embedded with AgNPs (reduced with *Heterotheca inuloides*) at different magnifications are shown in **Figure 3**. Ag nanoparticles of spherical in shape are observed distributed over the fiber surface.

*TEM images show the size distribution and a spherical shape of AgNPs synthesized by the green reducing agent,* 

*H. inuloides* represents a source of chemical compounds with variable structural patterns. Several different types of compounds such as sesquiterpenes, triterpenes, polyphenols, and phytosterols have been isolated from essential oil and organic extracts from various parts, including roots, aerial parts, and flowers. According to the abovementioned, the following characteristic functional groups, 3268 cm<sup>−</sup><sup>1</sup>

The antimicrobial activity of the infusion using *Heterotheca inuloides* as reducing agent, against *Staphylococcus aureus*, can be seen in **Figure 5**. A well-defined inhibition halo around the disk impregnated with the nanoparticles solution is visible.

(C = O), 1393 cm<sup>−</sup><sup>1</sup>

(CH), were detected (**Figure 4**).

(–CH2), 1258 cm<sup>−</sup><sup>1</sup>

**6**

**spectroscopy**

*having a mean diameter of approximately 17 nm.*

**Figure 2.**

(–OH), 2942 cm<sup>−</sup><sup>1</sup>

(–CH3), 1033 cm<sup>−</sup><sup>1</sup>

*SEM micrographs showing the catgut suture threads coated with AgNPs synthesized by the green reducing agent. (A) Images revealed that AgNPs were formed on the surface. (B) The micrograph shows a plain catgut suture.*

#### **Figure 4.** *FTIR spectrum of the* Heterotheca inuloides *aqueous extract.*

In **Figure 6**, the antimicrobial activity of catgut against *S. aureus* and *E. coli* is observed. The suture threads were cut into small pieces and put on the Petri dishes. Some suture thread samples were used as blank.

The inhibition zone for both strains is presented in the next tables.

**Table 1** shows that the use of *Heterotheca inuloides* to synthesize AgNPs produces an antibacterial effect against both strains, by testing disks. The growth inhibition

#### **Figure 5.**

*AgNPs against* Staphylococcus aureus: *(A) blank disk, (B) disk containing AgNPs synthesized by* H. inuloides*, and (C) disk with* H. inuloides *infusion as a control.*

#### **Figure 6.**

*Antibacterial effect of suture against both strains a and b. (A) Inhibitory halo of catgut suture with AgNPs versus E. coli. (B) Inhibitory halo of catgut suture with AgNPs versus S. aureus. (a) Catgut with AgNPs. (b) Catgut without AgNPs used as a blank.*

halo for *S. aureus* was on 3.5 mm average. While for *E. coli*, it was 3.25 mm on average. Without having a statistically significant difference between both strains.

When performing the suture inhibition test for both strains, an average inhibition zone of 3.46 mm for *S. aureus* and an inhibition zone of 2.8 mm for *E. coli* can be seen in **Table 2**, demonstrating a statistically significant difference and a greater zone of inhibition with the use of catgut versus *S. aureus*.

There was no growth inhibition with blank or control disks, neither with catgut blank sutures. All the measurements were replicated three times for each treatment.

#### **5. Discussion**

Regarding the UV-Vis results, we can recognize the presence of the characteristic surface plasmonic resonance of silver nanoparticles as other authors have reported to appear from 400 to 500 nm [14].

Other authors have shown that silver nanoparticles with sizes smaller than 50 nm offer high antimicrobial activity [15] that supported on catgut fibers and obtain a

**9**

**Variable** Sdis~pHi Edis~pHi combined

diff diff = mean(Sdisco\_NpHi) − mean(Edisco\_NpHi)

Ho: diff = 0 Ha: diff < 0 Pr(T < t) = 0.7315

**Table 1.** *Measures of the zones of inhibition of the disks against* S. aureus *and* E. coli*.*

Ha: diff != 0 Pr(|T| > |t|) = 0.5370

**Obs**

4 4 8

**Mean**

3.5 3.25 3.375

0.25

**Std. Err.** 0.2886751

0.25 0.1829813 0.3818813

**Std. Dev.** 0.5773503

0.5 0.5175492 t = 0.6547 degrees of freedom = 6

Ha: diff > 0 Pr(T > t) = 0.2685

**[95% Conf. Interval]**

2.581307–4.418693

2.454388–4.045612

2.942318–3.807682


*Green Synthesis of Silver Nanoparticles Using* Heterotheca inuloides *and Its Antimicrobial…*

*DOI: http://dx.doi.org/10.5772/intechopen.89344*

#### *Green Synthesis of Silver Nanoparticles Using* Heterotheca inuloides *and Its Antimicrobial… DOI: http://dx.doi.org/10.5772/intechopen.89344*


#### **Table 1.**

*Measures of the zones of inhibition of the disks against* S. aureus *and* E. coli*.*

*Engineered Nanomaterials - Health and Safety*

halo for *S. aureus* was on 3.5 mm average. While for *E. coli*, it was 3.25 mm on average. Without having a statistically significant difference between both strains. When performing the suture inhibition test for both strains, an average inhibition zone of 3.46 mm for *S. aureus* and an inhibition zone of 2.8 mm for *E. coli* can be seen in **Table 2**, demonstrating a statistically significant difference and a greater

*Antibacterial effect of suture against both strains a and b. (A) Inhibitory halo of catgut suture with AgNPs versus E. coli. (B) Inhibitory halo of catgut suture with AgNPs versus S. aureus. (a) Catgut with AgNPs.* 

*AgNPs against* Staphylococcus aureus: *(A) blank disk, (B) disk containing AgNPs synthesized by* H.

inuloides*, and (C) disk with* H. inuloides *infusion as a control.*

There was no growth inhibition with blank or control disks, neither with catgut blank sutures. All the measurements were replicated three times for each treatment.

Regarding the UV-Vis results, we can recognize the presence of the characteristic surface plasmonic resonance of silver nanoparticles as other authors have reported

Other authors have shown that silver nanoparticles with sizes smaller than 50 nm offer high antimicrobial activity [15] that supported on catgut fibers and obtain a

zone of inhibition with the use of catgut versus *S. aureus*.

**8**

**5. Discussion**

**Figure 5.**

**Figure 6.**

to appear from 400 to 500 nm [14].

*(b) Catgut without AgNPs used as a blank.*


 *When comparing both strains; there was a mean inhibition zone of 3.4 mm against* S. aureus*. While for* E. coli *there was a mean inhibition zone of 2.8 mm representing a statistical significant difference of 0.0230 value.*

**Table**

**11**

**6. Conclusion**

*Green Synthesis of Silver Nanoparticles Using* Heterotheca inuloides *and Its Antimicrobial…*

double function, in **Figure 3**. The accommodation of the nanoparticles on the surface of the fibers can be observed, and some authors have observed this same behavior [16]. Also, the main functional groups present in the reducing agent are recognized [1], which makes it possible to obtain silver nanoparticles with average sizes of

According to the Centers for Disease Control and Prevention, assessment of wound healing after a surgical procedure is important [17]. Infection is the most important and preventable cause of impaired wound healing. Microorganisms can

A surgical site infection (SSI) surveillance in oral or maxillofacial surgery is necessary because the mouth is widely colonized by highly pathogenic microorganisms. Besides, suture threads are placed in a moist environment [19]. One of the categories to classify the SSI is the complications related to the superficial incision, in which the suture material used may be related [20]. Whether its natural or synthetic origin, the sutures are strange to the body and therefore cause tissue reaction. Any suture may provide an environment conducive to the propagation of infection [21]. In 2002 the Food and Drug Administration (FDA) approved the use of the first suture coated with antimicrobial and triclosan (polyglactin 910-polychlorophenoxyphenol), which has a broad-spectrum activity against Gram-positive and

However, the resistance of highly pathogenic microorganisms has been reported

An advanced material for the closure of a wound, with direct drug delivery from

Plants have different types of metabolites that can help in the reduction of silver ions. The biological methods using plant leaf extracts have shown great potential for nano-synthesis [27]. Using endemic plants provides many advantages, such as

Some of the most important considerations of a green synthetic method are the use of nontoxic chemicals, benign solvents for the environment, and renewable materials [10, 32]. Besides, the process can be carried out at room temperature, and the reaction is completed in a few minutes. Green synthetic methods are simple, environmentally benign, and quite efficient for producing silver nanoparticles [10, 28].

We present a totally green approach toward the synthesis and stabilization of metal nanoparticles allowing to obtain an advanced suture that can be effective on oral and maxillofacial surgery, having demonstrated an antibacterial effect versus resistant bacteria. In this study, *Heterotheca inuloides* turns out to be an appropriate

Synthesis of AgNp by eco-friendly reducing agents represents an environmental and economically sustainable process that minimizes the costs and provides the

easy accessibility, simplicity, economy, and ecological nature [28–31].

reducing agent for coating natural suture threads with AgNPs.

benefits and properties of plants such as *Heterotheca inuloides*.

the suture to the surgical site, may be the key for the prevention of infections. Mexico is one of the five megadiverse countries of the world [23]. Pharmaceutical products derived from this plant are widely used, since ancient times, due to the botanical exploration of the Valley of Mexico, one of the most well-known regions from the scientific and botanical aspect [24]. The Ministry of Health has studied its traditional therapeutic use in most regions of the country, using the flower as an infusion and other presentations, [25] searching for the establishment of public policies, and recognizing the importance of epidemiological

*DOI: http://dx.doi.org/10.5772/intechopen.89344*

rapidly reach tissues after surgery [18].

Gram-negative microorganisms [12].

as a disadvantage of the use of triclosan [22].

contributions of popular medicine [26].

16.04 nm.

**2.**

#### *Engineered Nanomaterials - Health and Safety*

#### *Green Synthesis of Silver Nanoparticles Using* Heterotheca inuloides *and Its Antimicrobial… DOI: http://dx.doi.org/10.5772/intechopen.89344*

double function, in **Figure 3**. The accommodation of the nanoparticles on the surface of the fibers can be observed, and some authors have observed this same behavior [16].

Also, the main functional groups present in the reducing agent are recognized [1], which makes it possible to obtain silver nanoparticles with average sizes of 16.04 nm.

According to the Centers for Disease Control and Prevention, assessment of wound healing after a surgical procedure is important [17]. Infection is the most important and preventable cause of impaired wound healing. Microorganisms can rapidly reach tissues after surgery [18].

A surgical site infection (SSI) surveillance in oral or maxillofacial surgery is necessary because the mouth is widely colonized by highly pathogenic microorganisms. Besides, suture threads are placed in a moist environment [19]. One of the categories to classify the SSI is the complications related to the superficial incision, in which the suture material used may be related [20]. Whether its natural or synthetic origin, the sutures are strange to the body and therefore cause tissue reaction. Any suture may provide an environment conducive to the propagation of infection [21].

In 2002 the Food and Drug Administration (FDA) approved the use of the first suture coated with antimicrobial and triclosan (polyglactin 910-polychlorophenoxyphenol), which has a broad-spectrum activity against Gram-positive and Gram-negative microorganisms [12].

However, the resistance of highly pathogenic microorganisms has been reported as a disadvantage of the use of triclosan [22].

An advanced material for the closure of a wound, with direct drug delivery from the suture to the surgical site, may be the key for the prevention of infections.

Mexico is one of the five megadiverse countries of the world [23]. Pharmaceutical products derived from this plant are widely used, since ancient times, due to the botanical exploration of the Valley of Mexico, one of the most well-known regions from the scientific and botanical aspect [24]. The Ministry of Health has studied its traditional therapeutic use in most regions of the country, using the flower as an infusion and other presentations, [25] searching for the establishment of public policies, and recognizing the importance of epidemiological contributions of popular medicine [26].

Plants have different types of metabolites that can help in the reduction of silver ions. The biological methods using plant leaf extracts have shown great potential for nano-synthesis [27]. Using endemic plants provides many advantages, such as easy accessibility, simplicity, economy, and ecological nature [28–31].

Some of the most important considerations of a green synthetic method are the use of nontoxic chemicals, benign solvents for the environment, and renewable materials [10, 32]. Besides, the process can be carried out at room temperature, and the reaction is completed in a few minutes. Green synthetic methods are simple, environmentally benign, and quite efficient for producing silver nanoparticles [10, 28].

#### **6. Conclusion**

We present a totally green approach toward the synthesis and stabilization of metal nanoparticles allowing to obtain an advanced suture that can be effective on oral and maxillofacial surgery, having demonstrated an antibacterial effect versus resistant bacteria. In this study, *Heterotheca inuloides* turns out to be an appropriate reducing agent for coating natural suture threads with AgNPs.

Synthesis of AgNp by eco-friendly reducing agents represents an environmental and economically sustainable process that minimizes the costs and provides the benefits and properties of plants such as *Heterotheca inuloides*.

*Engineered Nanomaterials - Health and Safety*

**10**

**Two-sample t test with equal variances**

**Variable** Scatgu~i Ecatgu~i combined

diff diff = mean(Scatgut\_NpHi) − mean(Ecatgut\_NpHi)

Ho: diff = 0 Ha: diff < 0 Pr(T < t) = 0.9885

**Table 2.** *difference of 0.0230 value.*

Ha: diff != 0 Pr(|T| > |t|) = 0.0230

*When comparing both strains; there was a mean inhibition zone of 3.4 mm against* S. aureus*. While for* E. coli *there was a mean inhibition zone of 2.8 mm representing a statistical significant* 

**Obs**

15 15 30

2.8 3.133333 0.6666667

**Mean** 3.466667

**Std. Err.** 0.1652319 0.2225395 0.1495844 0.2771739

**Std. Dev.** 0.6399405 0.8618916 0.8193072

t = 2.4052

degrees of freedom = 28

Ha: diff > 0

Pr(T > t) = 0.0115

**[95% Conf. Interval]**

3.112279–3.821054

2.3227–3.2773

2.827399–3.439268

0.0989016–1.234432

We believe that this may be an alternative for surgeons, which helps in reducing the indiscriminate use of antibiotic therapy. It also represents an option to use advanced materials that are produced under sustainable conditions, which reduce the impact on the environment.

## **Conflict of interest**

The authors declare that they do not have conflict of interest.

## **Author details**

Saraí C. Guadarrama-Reyes1 , Raúl A. Morales-Luckie2 \*, Víctor Sánchez-Mendieta<sup>2</sup> , María G. González-Pedroza<sup>2</sup> , Edith Lara-Carrillo3 , Ulises Velazquez-Enriquez<sup>3</sup> , Victor Toral-Rizo3 and Rogelio Scougall-Vilchis3

1 School of Dentistry, Autonomous University of the State of Mexico, Toluca, State of Mexico, Mexico

2 Joint Center for Research in Sustainable Chemistry UAEM-UNAM (CCIQS), Autonomous University of the State of Mexico, Toluca, State of Mexico, Mexico

3 Center for Research and Advanced Studies in Dentistry, School of Dentistry, Autonomous University of the State of Mexico, Toluca, State of Mexico, Mexico

\*Address all correspondence to: rmoralesl@uaemex.mx; ramluckie@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**13**

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[11] Jaidev L, Narasimha G. Fungal mediated biosynthesis of silver nanoparticles, characterization and antimicrobial activity. Colloids and Surfaces B: Biointerfaces.

[12] Granados-Romero JJ et al. Comparación entre sutura recubierta con antibacterial versus cierre tradicional en la incidencia de

complicaciones en apendicectomías y colecistectomías laparoscópicas. Revista Mexicana de Cirugía Endoscópica.

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[16] Aramwit P et al. Green synthesis of silk sericin-capped silver nanoparticles

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*DOI: http://dx.doi.org/10.5772/intechopen.89344*

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[2] Delgado G et al. Anti-inflammatory

*inuloides*. Journal of Natural Products.

[3] Coballase-Urrutia E et al. Antioxidant

extracts and of some of its metabolites.

[5] Rosas-Piñón Y et al. Ethnobotanical survey and antibacterial activity of plants used in the Altiplane region of Mexico for the treatment

[6] World Health Organization. General Guidelines for Methodologies on Research and Evaluation of Traditional Medicine. Geneva: World Health

[7] Gené RM et al. *Heterotheca inuloides*: Anti-inflammatory and analgesic effect. Journal of Ethnopharmacology.

[8] Kubo I et al. Antimicrobial agents from *Heterotheca inuloides*. Planta Medica. 1994;**60**(03):218-221

[9] Rodríguez-Chávez JL et al. In vitro activity of 'Mexican Arnica' *Heterotheca inuloides* Cass natural products and some derivatives against

constituents from *Heterotheca* 

activity of *Heterotheca inuloides*

Toxicology. 2010;**276**(1):41-48

[4] Coballase-Urrutia E et al. Hepatoprotective effect of acetonic and methanolic extracts of *Heterotheca inuloides* against CCl4-induced toxicity in rats. Experimental and Toxicologic Pathology. 2011;**63**(4):363-370

of oral cavity infections. Journal of Ethnopharmacology.

2012;**141**(3):860-865

Organization; 2000

1998;**60**(2):157-162

2001;**64**(7):861-864

**References**

*Green Synthesis of Silver Nanoparticles Using* Heterotheca inuloides *and Its Antimicrobial… DOI: http://dx.doi.org/10.5772/intechopen.89344*

#### **References**

*Engineered Nanomaterials - Health and Safety*

the impact on the environment.

**Conflict of interest**

**Author details**

Victor Toral-Rizo3

Saraí C. Guadarrama-Reyes1

María G. González-Pedroza<sup>2</sup>

Toluca, State of Mexico, Mexico

provided the original work is properly cited.

We believe that this may be an alternative for surgeons, which helps in reducing the indiscriminate use of antibiotic therapy. It also represents an option to use advanced materials that are produced under sustainable conditions, which reduce

, Raúl A. Morales-Luckie2

, Edith Lara-Carrillo3

2 Joint Center for Research in Sustainable Chemistry UAEM-UNAM (CCIQS), Autonomous University of the State of Mexico, Toluca, State of Mexico, Mexico

3 Center for Research and Advanced Studies in Dentistry, School of Dentistry, Autonomous University of the State of Mexico, Toluca, State of Mexico, Mexico

\*Address all correspondence to: rmoralesl@uaemex.mx; ramluckie@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

and Rogelio Scougall-Vilchis3

1 School of Dentistry, Autonomous University of the State of Mexico,

\*, Víctor Sánchez-Mendieta<sup>2</sup>

, Ulises Velazquez-Enriquez<sup>3</sup>

,

,

The authors declare that they do not have conflict of interest.

**12**

[1] Rodríguez-Chávez JL et al. Mexican Arnica (*Heterotheca inuloides* Cass. Asteraceae: Astereae): Ethnomedical uses, chemical constituents and biological properties. Journal of Ethnopharmacology. 2017;**195**:39-63

[2] Delgado G et al. Anti-inflammatory constituents from *Heterotheca inuloides*. Journal of Natural Products. 2001;**64**(7):861-864

[3] Coballase-Urrutia E et al. Antioxidant activity of *Heterotheca inuloides* extracts and of some of its metabolites. Toxicology. 2010;**276**(1):41-48

[4] Coballase-Urrutia E et al. Hepatoprotective effect of acetonic and methanolic extracts of *Heterotheca inuloides* against CCl4-induced toxicity in rats. Experimental and Toxicologic Pathology. 2011;**63**(4):363-370

[5] Rosas-Piñón Y et al. Ethnobotanical survey and antibacterial activity of plants used in the Altiplane region of Mexico for the treatment of oral cavity infections. Journal of Ethnopharmacology. 2012;**141**(3):860-865

[6] World Health Organization. General Guidelines for Methodologies on Research and Evaluation of Traditional Medicine. Geneva: World Health Organization; 2000

[7] Gené RM et al. *Heterotheca inuloides*: Anti-inflammatory and analgesic effect. Journal of Ethnopharmacology. 1998;**60**(2):157-162

[8] Kubo I et al. Antimicrobial agents from *Heterotheca inuloides*. Planta Medica. 1994;**60**(03):218-221

[9] Rodríguez-Chávez JL et al. In vitro activity of 'Mexican Arnica' *Heterotheca inuloides* Cass natural products and some derivatives against *Giardia intestinalis*. Parasitology. 2015;**142**(4):576-584

[10] Roy N et al. Green synthesis of silver nanoparticles: An approach to overcome toxicity. Environmental Toxicology and Pharmacology. 2013;**36**(3):807-812

[11] Jaidev L, Narasimha G. Fungal mediated biosynthesis of silver nanoparticles, characterization and antimicrobial activity. Colloids and Surfaces B: Biointerfaces. 2010;**81**(2):430-433

[12] Granados-Romero JJ et al. Comparación entre sutura recubierta con antibacterial versus cierre tradicional en la incidencia de complicaciones en apendicectomías y colecistectomías laparoscópicas. Revista Mexicana de Cirugía Endoscópica. 2015;**16**(1-4):31-36

[13] Corrêa JM et al. Silver nanoparticles in dental biomaterials. International Journal of Biomaterials. 2015;**2015**:485275

[14] Sharma VK, Yngard RA, Lin Y. Silver nanoparticles: Green synthesis and their antimicrobial activities. Advances in Colloid and Interface Science. 2009;**145**(1-2):83-96

[15] Morales-Luckie RA et al. Synthesis of silver nanoparticles using aqueous extracts of *Heterotheca inuloides* as reducing agent and natural fibers as templates: *Agave lechuguilla* and silk. Materials Science and Engineering: C. 2016;**69**:429-436

[16] Aramwit P et al. Green synthesis of silk sericin-capped silver nanoparticles and their potent anti-bacterial activity. Nanoscale Research Letters. 2014;**9**(1):79

[17] Mangram AJ et al. Guideline for prevention of surgical site infection, 1999. Infection Control and Hospital Epidemiology. 1999;**20**(4):247-280

[18] Bickler SW, Spiegel D. Improving surgical care in low-and middle-income countries: A pivotal role for the World Health Organization. World Journal of Surgery. 2010;**34**(3):386-390

[19] Leknes KN et al. Tissue reactions to sutures in the presence and absence of anti-infective therapy. Journal of Clinical Periodontology. 2005;**32**(2):130-138

[20] Kathju S et al. Chronic surgical site infection due to suture-associated polymicrobial biofilm. Surgical Infections. 2009;**10**(5):457-461

[21] Fantry AJ et al. Deep infections after Syndesmotic fixation with a suture button device. Orthopedics. 2017;**40**(3):e541-e545

[22] Edmiston CE Jr, Daoud FC, Leaper D. Is there an evidence-based argument for embracing an antimicrobial (triclosan)-coated suture technology to reduce the risk for surgical-site infections? A metaanalysis. Surgery. 2013;**154**(1):89-100

[23] Castillo-Juárez I et al. Anti-*Helicobacter pylori* activity of plants used in Mexican traditional medicine for gastrointestinal disorders. Journal of Ethnopharmacology. 2009;**122**(2):402-405

[24] Rzedowski GD, Rzedowski J. Flora Fanerogámica del Valle de México. 1a reimp ed. Pátzcuaro, Michoacán: Instituto de Ecología, AC y Comisión Nacional para el Conocimiento y Usos de la Biodiversidad; 2005

[25] Hernández-Cruz AS. Manual para el manejo sustentable de plantas medicinales y elaboración de productos derivados. Instituto Nacional de Desarrollo Social, Indesol. México. 2014:63. Folio CS-09-F-DI-308-14

[26] Almaguer G. Programa de Trabajo 2001-2006 de la Dirección de Medicina Tradicional. Coordinación de Salud para los Pueblos Indígenas. México, DF: Secretaría de Salud; 2001. Manuscrito

[27] Shinde N, Lokhande A, Lokhande C. A green synthesis method for large area silver thin film containing nanoparticles. Journal of Photochemistry and Photobiology B: Biology. 2014;**136**:19-25

[28] Behravan M et al. Facile green synthesis of silver nanoparticles using *Berberis vulgaris* leaf and root aqueous extract and its antibacterial activity. International Journal of Biological Macromolecules. 2019;**124**:148-154

[29] Anand KKH, Mandal BK. Activity study of biogenic spherical silver nanoparticles towards microbes and oxidants. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 2015;**135**:639-645

[30] Bindhu M, Umadevi M. Antibacterial and catalytic activities of green synthesized silver nanoparticles. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 2015;**135**:373-378

[31] Ulug B et al. Role of irradiation in the green synthesis of silver nanoparticles mediated by fig (*Ficus carica*) leaf extract. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 2015;**135**:153-161

[32] Raveendran P, Fu J, Wallen SL. Completely "green" synthesis and stabilization of metal nanoparticles. Journal of the American Chemical Society. 2003;**125**(46):13940-13941

**15**

**Chapter 2**

**Abstract**

*Takalani Cele*

metal nanoparticles

**1. Introduction**

**2.1 Chemical methods**

*2.1.1 The polyol method*

Preparation of Nanoparticles

render them most appropriate for a number of specialist applications.

**Keywords:** nanoparticles, physical methods, chemical methods, synthesis,

sonochemical method [4], radiolytic [5] and photochemical [6] method.

The Polyol method is a chemical method for the synthesis of nanoparticles. This method uses nonaqueous liquid (polyol) as a solvent and reducing agent. The nonaqueous solvents that are used in this method have an advantage of minimizing surface oxidation and agglomeration. This method allows flexibility on controlling of size, texture, and shape of nanoparticles. Polyol method can also be

**2. Methods of synthesis of metal nanoparticles**

used in producing nanoparticles in large scale [7].

Innovative developments of science and engineering have progressed very fast toward the synthesis of nanomaterials to achieve unique properties that are not the same as the properties of the bulk materials. The particle reveals interesting properties at the dimension below 100 nm, mostly from two physical effects. The two physical effects are the quantization of electronic states apparent leading to very sensitive size-dependent effects such as optical and magnetic properties and the high surface-to-volume ratio modifies the thermal, mechanical, and chemical properties of materials. The nanoparticles' unique physical and chemical properties

Several methods have been developed to produce metal nanoparticles. Two synthesis approaches have been identified that is top-down and bottom-up approach. Top-down methods comprise of milling, lithography, and repeated quenching. This approach does not have good control of the particle size and structure. Bottom-up method is the approach that is mostly used by scientists in the synthesis of nanoparticles as it involves building up a material from bottom: atom-by-atom, molecule-bymolecule, and cluster-by-cluster [1, 2]. Several chemical routes have been identified to synthesize the colloidal metal nanoparticles from different precursors using chemical reductants in solvents (aqueous and nonaqueous). The chemical routes that have been studied for various applications include electrochemical method [3],

## **Chapter 2** Preparation of Nanoparticles

*Takalani Cele*

## **Abstract**

*Engineered Nanomaterials - Health and Safety*

1999. Infection Control and Hospital Epidemiology. 1999;**20**(4):247-280

[26] Almaguer G. Programa de Trabajo 2001-2006 de la Dirección de Medicina Tradicional. Coordinación de Salud para los Pueblos Indígenas. México, DF: Secretaría de Salud; 2001. Manuscrito

Lokhande C. A green synthesis method

containing nanoparticles. Journal of Photochemistry and Photobiology B:

[28] Behravan M et al. Facile green synthesis of silver nanoparticles using *Berberis vulgaris* leaf and root aqueous extract and its antibacterial activity. International Journal of Biological Macromolecules. 2019;**124**:148-154

[29] Anand KKH, Mandal BK. Activity study of biogenic spherical silver nanoparticles towards microbes and oxidants. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 2015;**135**:639-645

Antibacterial and catalytic activities of green synthesized silver nanoparticles. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy.

[31] Ulug B et al. Role of irradiation in the green synthesis of silver nanoparticles mediated by fig (*Ficus carica*) leaf extract. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 2015;**135**:153-161

[32] Raveendran P, Fu J, Wallen SL. Completely "green" synthesis and stabilization of metal nanoparticles. Journal of the American Chemical Society. 2003;**125**(46):13940-13941

[30] Bindhu M, Umadevi M.

2015;**135**:373-378

[27] Shinde N, Lokhande A,

for large area silver thin film

Biology. 2014;**136**:19-25

[18] Bickler SW, Spiegel D. Improving surgical care in low-and middle-income countries: A pivotal role for the World Health Organization. World Journal of

[19] Leknes KN et al. Tissue reactions to sutures in the presence and absence of anti-infective therapy. Journal of Clinical Periodontology.

[20] Kathju S et al. Chronic surgical site infection due to suture-associated polymicrobial biofilm. Surgical Infections. 2009;**10**(5):457-461

[21] Fantry AJ et al. Deep infections after Syndesmotic fixation with a suture button device. Orthopedics.

[22] Edmiston CE Jr, Daoud FC, Leaper D. Is there an evidence-based

[23] Castillo-Juárez I et al. Anti-*Helicobacter pylori* activity of plants used in Mexican traditional medicine

for gastrointestinal disorders. Journal of Ethnopharmacology.

[24] Rzedowski GD, Rzedowski J. Flora Fanerogámica del Valle de México. 1a reimp ed. Pátzcuaro, Michoacán: Instituto de Ecología, AC y Comisión Nacional para el Conocimiento y Usos

2009;**122**(2):402-405

de la Biodiversidad; 2005

[25] Hernández-Cruz AS. Manual para el manejo sustentable de plantas medicinales y elaboración de productos derivados. Instituto Nacional de Desarrollo Social, Indesol. México. 2014:63. Folio CS-09-F-DI-308-14

argument for embracing an antimicrobial (triclosan)-coated suture technology to reduce the risk for surgical-site infections? A metaanalysis. Surgery. 2013;**154**(1):89-100

Surgery. 2010;**34**(3):386-390

2005;**32**(2):130-138

2017;**40**(3):e541-e545

**14**

Innovative developments of science and engineering have progressed very fast toward the synthesis of nanomaterials to achieve unique properties that are not the same as the properties of the bulk materials. The particle reveals interesting properties at the dimension below 100 nm, mostly from two physical effects. The two physical effects are the quantization of electronic states apparent leading to very sensitive size-dependent effects such as optical and magnetic properties and the high surface-to-volume ratio modifies the thermal, mechanical, and chemical properties of materials. The nanoparticles' unique physical and chemical properties render them most appropriate for a number of specialist applications.

**Keywords:** nanoparticles, physical methods, chemical methods, synthesis, metal nanoparticles

#### **1. Introduction**

Several methods have been developed to produce metal nanoparticles. Two synthesis approaches have been identified that is top-down and bottom-up approach. Top-down methods comprise of milling, lithography, and repeated quenching. This approach does not have good control of the particle size and structure. Bottom-up method is the approach that is mostly used by scientists in the synthesis of nanoparticles as it involves building up a material from bottom: atom-by-atom, molecule-bymolecule, and cluster-by-cluster [1, 2]. Several chemical routes have been identified to synthesize the colloidal metal nanoparticles from different precursors using chemical reductants in solvents (aqueous and nonaqueous). The chemical routes that have been studied for various applications include electrochemical method [3], sonochemical method [4], radiolytic [5] and photochemical [6] method.

## **2. Methods of synthesis of metal nanoparticles**

#### **2.1 Chemical methods**

#### *2.1.1 The polyol method*

The Polyol method is a chemical method for the synthesis of nanoparticles. This method uses nonaqueous liquid (polyol) as a solvent and reducing agent. The nonaqueous solvents that are used in this method have an advantage of minimizing surface oxidation and agglomeration. This method allows flexibility on controlling of size, texture, and shape of nanoparticles. Polyol method can also be used in producing nanoparticles in large scale [7].

The polyol process can be taken as a sol-gel method in the synthesis of oxide, if the synthesis is conducted at moderately increased temperature with accurate particle growth control [8]. There are several reports that have studied the synthesis of oxide sub-micrometer particles and these include Y2O3, VxOy,Mn3O4, ZnO, CoTiO3, SnO2, PbO, and TiO2 [9–16].

The solvent that is mostly used in polyol method in metal oxide nanoparticles synthesis is ethylene glycol because of its strong reducing capability, high dielectric constant, and high boiling point. Ethylene glycol is also used as a crosslinking reagent to link with metal ion to form metal glycolate leading to oligomerization [17]. It has been reported that as-synthesized glycolate precursors can be converted to their more common metal oxide derivatives when calcined in air, while maintaining the original precursor morphology [8].

The polyol synthesis process has also been used for the synthesis of bimetallic alloys and core-shell nanoparticles [18–20]. Yang and co-workers used polyol method to produce icosahedral and cubic gold particles on the order of 100–300 nm by careful regulation of the growth rate for each crystallographic direction [21]. Xia and co-workers reported the production of controlled morphologies such as nanocubes and nanowires by controlling the molar ratio between silver nitrate and *PVP* [22].

#### *2.1.2 Microemulsions*

An emulsion is a liquid in liquid dispersion. A solution of polymers can produce emulsions as it is liquid. Emulsions are divided according to the size of droplet, i.e., macro-emulsions, mini-emulsions, and micro-emulsions [23].

Micro-emulsion synthesis method is widely used for the production of inorganic nanoparticles [24]. When oil and water are mixed, they separate into two phases as they are immiscible [25]. The energy input is required to mix the two phases to create water-oil.

An attempt to combine the two phases requires energy input that would establish water-oil connection replacing the water-water/oil-oil contacts. The interfacial tension between bulk oil and water can be as high as 30–50 dynes/cm and this can be avoided by using surfactants (surface-active molecules). Surfactants contain hydrophilic (water-loving) and lipophilic (oil-loving) groups [26]. The interface can be aligned and established between oil and water by reducing the interfacial tension if there are enough surfactant molecules.

The preparation procedure of metallic nanoparticles in water in oil microemulsion commonly consists of mixing of two microemulsions containing metal salt and a reducing agent, respectively as shown in **Figure 1**.

Brownian motion is formed after the exchange of reactants (collision) between micelles that happens after mixing two microemulsions. Good collisions result into coalescence, fusion, and mixing well of the reactants. Metal nuclei are formed from the reaction between solubilizates. Bönnemann et al. reported the formation of zerovalent metal atoms at nucleation stage from reducing a metal salt, which can collide with additional metal ions, metal atoms, or clusters to form an irreversible seed of stable metal nuclei [28].

The growth stage happens around the nucleation point, where successful collision occurs between a reverse micelle moving a nucleus and another one moving the product monomers with the arrival of more reactants due to intermicellar exchange. The morphology and size of nanoparticles are based on the size and shape of the nanodroplets and the type of the surfactant. The surfactant is usually used to stabilize the particle and protect them from proceeding to grow [28].

**17**

emulsion [29].

**Figure 1.**

for 12 h [30].

nanoparticles were produced [31].

*Preparation of Nanoparticles*

*DOI: http://dx.doi.org/10.5772/intechopen.90771*

Wongwailikhit et al. reported the formation of iron (III) oxide, Fe2O3 using water in oil microemulsion by combining the required amount of H2O in a stock solution of Sodium Bis (2-Ethylhexyl) Sulfosuccinate (AOT) in *n*-heptane. The solution was left overnight, then the concentrated Hydroxylamine (NH2OH) and FeCl3 were mixed into the water in oil microemulsion. Suspension of Fe2O3 was filtered and washed with 95% ethanol and dried at 300°C for 3 h. The product was spherical, monodisperse nanoparticles with diameter of about 50 nm. The size of particles depended on the water content in microemulsion system. The increase of particles size was achieved with increasing the water fraction in water in oil micro-

*Schematic illustration of nanoparticles preparation using microemulsion techniques: Particle formation steps. Kchem is the rate constant for chemical reaction, kex is the rate constant for intermicellar exchange dynamics, kn*

*is the rate constant for nucleation, and kg is the rate constant for particle growth [27].*

Sarkar et al. reported the formation of pure monodispersed zinc oxide nanoparticles of different shapes. Microemulsion was composed of cyclohexane, Triton X-100 as surfactant, hexanol as cosurfactant and aqueous solution of zinc nitrate or ammonium hydroxide/sodium hydroxide complex. The molar ratio of TX-100 to hexanol was maintained at 1:4. The microemulsion containing ammonium hydroxide/sodium hydroxide was added to microemulsion containing zinc nitrate and stirred. The nanoparticles were then separated by centrifuging at 15,000 rpm for 1 h. The particles were washed with distilled water and alcohol and dried at 50°C

Maitra was the first to establish Chitosan nanoparticles by microemulsion technique. Chitosan nanoparticles were prepared in the aqueous core of reverse micellar droplets and crosslinked through glutaraldehyde. Surfactant dissolved in N-hexane was also used with chitosan in acetic acid and glutaraldehyde was added in the surfactant at room temperature. The mixture was stirred continuously and

**Figure 1.**

*Engineered Nanomaterials - Health and Safety*

ing the original precursor morphology [8].

SnO2, PbO, and TiO2 [9–16].

*PVP* [22].

*2.1.2 Microemulsions*

create water-oil.

The polyol process can be taken as a sol-gel method in the synthesis of oxide, if the synthesis is conducted at moderately increased temperature with accurate particle growth control [8]. There are several reports that have studied the synthesis of oxide sub-micrometer particles and these include Y2O3, VxOy,Mn3O4, ZnO, CoTiO3,

The solvent that is mostly used in polyol method in metal oxide nanoparticles synthesis is ethylene glycol because of its strong reducing capability, high dielectric constant, and high boiling point. Ethylene glycol is also used as a crosslinking reagent to link with metal ion to form metal glycolate leading to oligomerization [17]. It has been reported that as-synthesized glycolate precursors can be converted to their more common metal oxide derivatives when calcined in air, while maintain-

The polyol synthesis process has also been used for the synthesis of bimetallic alloys and core-shell nanoparticles [18–20]. Yang and co-workers used polyol method to produce icosahedral and cubic gold particles on the order of 100–300 nm by careful regulation of the growth rate for each crystallographic direction [21]. Xia and co-workers reported the production of controlled morphologies such as nanocubes and nanowires by controlling the molar ratio between silver nitrate and

An emulsion is a liquid in liquid dispersion. A solution of polymers can produce emulsions as it is liquid. Emulsions are divided according to the size of droplet, i.e.,

Micro-emulsion synthesis method is widely used for the production of inorganic nanoparticles [24]. When oil and water are mixed, they separate into two phases as they are immiscible [25]. The energy input is required to mix the two phases to

An attempt to combine the two phases requires energy input that would establish water-oil connection replacing the water-water/oil-oil contacts. The interfacial tension between bulk oil and water can be as high as 30–50 dynes/cm and this can be avoided by using surfactants (surface-active molecules). Surfactants contain hydrophilic (water-loving) and lipophilic (oil-loving) groups [26]. The interface can be aligned and established between oil and water by reducing the interfacial

The preparation procedure of metallic nanoparticles in water in oil microemulsion commonly consists of mixing of two microemulsions containing metal salt and

Brownian motion is formed after the exchange of reactants (collision) between micelles that happens after mixing two microemulsions. Good collisions result into coalescence, fusion, and mixing well of the reactants. Metal nuclei are formed from the reaction between solubilizates. Bönnemann et al. reported the formation of zerovalent metal atoms at nucleation stage from reducing a metal salt, which can collide with additional metal ions, metal atoms, or clusters to form an irreversible

The growth stage happens around the nucleation point, where successful collision occurs between a reverse micelle moving a nucleus and another one moving the product monomers with the arrival of more reactants due to intermicellar exchange. The morphology and size of nanoparticles are based on the size and shape of the nanodroplets and the type of the surfactant. The surfactant is usually used to

stabilize the particle and protect them from proceeding to grow [28].

macro-emulsions, mini-emulsions, and micro-emulsions [23].

tension if there are enough surfactant molecules.

a reducing agent, respectively as shown in **Figure 1**.

seed of stable metal nuclei [28].

**16**

*Schematic illustration of nanoparticles preparation using microemulsion techniques: Particle formation steps. Kchem is the rate constant for chemical reaction, kex is the rate constant for intermicellar exchange dynamics, kn is the rate constant for nucleation, and kg is the rate constant for particle growth [27].*

Wongwailikhit et al. reported the formation of iron (III) oxide, Fe2O3 using water in oil microemulsion by combining the required amount of H2O in a stock solution of Sodium Bis (2-Ethylhexyl) Sulfosuccinate (AOT) in *n*-heptane. The solution was left overnight, then the concentrated Hydroxylamine (NH2OH) and FeCl3 were mixed into the water in oil microemulsion. Suspension of Fe2O3 was filtered and washed with 95% ethanol and dried at 300°C for 3 h. The product was spherical, monodisperse nanoparticles with diameter of about 50 nm. The size of particles depended on the water content in microemulsion system. The increase of particles size was achieved with increasing the water fraction in water in oil microemulsion [29].

Sarkar et al. reported the formation of pure monodispersed zinc oxide nanoparticles of different shapes. Microemulsion was composed of cyclohexane, Triton X-100 as surfactant, hexanol as cosurfactant and aqueous solution of zinc nitrate or ammonium hydroxide/sodium hydroxide complex. The molar ratio of TX-100 to hexanol was maintained at 1:4. The microemulsion containing ammonium hydroxide/sodium hydroxide was added to microemulsion containing zinc nitrate and stirred. The nanoparticles were then separated by centrifuging at 15,000 rpm for 1 h. The particles were washed with distilled water and alcohol and dried at 50°C for 12 h [30].

Maitra was the first to establish Chitosan nanoparticles by microemulsion technique. Chitosan nanoparticles were prepared in the aqueous core of reverse micellar droplets and crosslinked through glutaraldehyde. Surfactant dissolved in N-hexane was also used with chitosan in acetic acid and glutaraldehyde was added in the surfactant at room temperature. The mixture was stirred continuously and nanoparticles were produced [31].

#### *2.1.3 Thermal decomposition*

Thermal decomposition also known as thermolysis is a chemical decomposition that is caused by heat. In this method, the heat is required to break chemical bonds in the compound undergoing decomposition and the reaction is endothermic. If decomposition is sufficiently exothermic, a positive feedback loop is created producing thermal runaway [32].

Arshad et al. reported on thermal decomposition of metal complexes of type MLX2 [M = Co (II), Cu (II), Zn (II), and Cd (II);L = DIE; X = NO3 <sup>1</sup>*<sup>−</sup>*] by TG-DTA-DTG techniques in air atmosphere. They synthesized nitrate complexes of transition metals with 1,2-diimidazoloethane (DIE) of the general formula M(DIE) (NO3)2. The study was conducted by thermoanalytical techniques in static air atmosphere to study the thermal behavior of these complexes and to determine their mode of decomposition. The complexes and ligands decomposed in a two-step process when heated to 740°. Above 740°, the residue was found to correspond with metal oxide. The thermal stability of the complexes increases in the following series: Co(II) *<* Cu(II) *<* Zn(II) *<* Cd(II) [33].

Patil et al. studied infrared spectra and thermal decompositions of metal acetates and dicarboxylates. The study was done to determine the metal-acetate bonding and the thermal decomposition of lead, copper, and rare earth acetates was studied by means of thermogravimetric analysis and differential thermal analysis. The investigations on decomposition products yielded good results [34].

George et al. reported on the mechanism of thermal decomposition of *n*-Buty l (tri-*n*-butylphosphine) copper (I). This study provided the first easily interpretable example in which succeeding reaction of a metal hydride and its parent metal alkyl was found to be vital in determining the products of a thermal decomposition [35].

Thermal decomposition of bismuth and silver carboxylates was investigated by means of TG, DSC, mass spectrometry, X-ray analysis, and electron microscopy Logvinenko et al. [36]. Non-isothermal thermogravimetric data were used for kinetic studies. All decomposition processes had multi-step character [36].

Ewell et al. investigated nearly pure talc both unheated and after heating at various temperatures ranging up to 1,435°C. The research included the measurement of heat effects, weight losses, and changes in true specific gravity occurring on heating talc. There was no change in the crystal structure of the talc heated up to 800°C. At the temperature between 800 and 8400°C, the talc decomposed to enstatite, amorphous silica, and water vapor. At the temperature approximately 1,200°C, the enstatite steadily changed to clinoenstatite and the amorphous silica changed to cristobalite approximately 1,300°C, giving clinoenstatite and cristobalite as end products [37].

#### *2.1.4 Electrochemical synthesis*

Electrochemical synthesis is the synthesis of chemical compounds in an electrochemical cell. The main advantage of electrochemical synthesis over an ordinary chemical reaction is rejection of the potential wasteful alternative half-reaction and the ability to accurately tune the preferred potential [38].

Electrochemical synthesis of silver nanoparticles has been extensively studied in the previous years. The method of electrochemical that was used was based on the dissolution of a metallic anode in an aprotic solvent. The silver nanoparticles that were produced by electroreduction of anodically solved silver ions in acetonitrile containing tetrabutylammonium ranged from 2 to 7 nm. The particle size was obtained by varying the current density. Different types of counter electrodes were used to study the effect of the different electrochemical parameters on the

**19**

*Preparation of Nanoparticles*

clusters [39].

agglomeration [40].

obtained [41].

the surface of the cathode [43].

had a particle size below 50 nm [44].

wide particle size distribution [45].

**2.2 Physical methods**

*2.2.1 Plasma*

*DOI: http://dx.doi.org/10.5772/intechopen.90771*

end particle size. The UV-Vis spectra showed the presence of two different silver

Dobre et al. also reported on the electrochemical synthesis of colloidal silver solutions using "sacrificial anode" technique conducted with a home-built current pulse generator with alternating polarity and a stirrer. Poly (N-vinyl-2-pyrrolidone) (PVP) and sodium lauryl sulfate (Na-LS) were used as a stabilizer and co-stabilizer, correspondingly. Spherical Ag particles with the size approximately 10–55 nm were synthesized. The UV/Vis spectra showed the absorption band at 420 nm, which is the evidence of the presence of Ag nanoparticles. The zeta potential values between −17 and −35 mV suggested a presence of particles covered by stabilizer with a slight

More research was done on the electrochemical synthesis of silver nanoparticles in aqueous poly (vinyl alcohol) solution (PVA). PVA is a low price widely used synthetic polymer with properties such as nontoxicity, water solubility, biocompatibility, biodegradability, and excellent mechanical properties. The experi-

time of 10 min. Silver nanoparticles with an average diameter of 15 ± 9 nm were

The electrochemical synthesis of red fluorescent Silicon (Si) nanoparticles stabilized with styrene. Si nanoparticles emit fluorescence under UV excitation, which is great for optics applications, etc. It was found that the liberated silicon particles in ethanol solution interact with styrene, which resulted in the substitution of Si-H bonds with those of Si-C. The developed styrene-coated Si nanoparticles exhibited a stable, bright, red fluorescence under excitation with a 365 nm UV light, and resulted into approximately 100 mg per Si wafer with a synthesis time of 2 h [42]. More investigations were done on the preparation of long-lived silver nanoparticles in aqueous solutions and silver powders using electrochemical method. The produced silver nanoparticles had a size distribution ranging from 2 to 20 nm and the nanoparticles remained stable for more than 7 years. Silver crystals containing agglomerated silver nanoparticles with sizes below 40 nm was found growing on

The research was conducted on using electrochemical method to synthesize highly pure silver nanoparticles. This method was used as it is one-step less expensive procedure and easy to control at room temperature and it does not use dangerous chemicals. The experimental setup brought up the oxidation of the anode and reduction of the cathode. The silver nanoparticles synthesized were spherical and

Islam et al. explored on the synthesis of platinum nanoparticles by electrochemi-

Plasma method is another method that is used to produce nanoparticles. The plasma is generated by radio frequency (RF) heating coils. The initial metal is enclosed in a pestle and the pestle is enclosed in an evacuated chamber. The metal is then heated above its evaporation point by high voltage RF coils wrapped around the evacuated chamber. The gas that is used in the procedure is Helium (He), which

cal deposition method. The particle size was controlled by varying electrolysis parameters and homogeneity of platinum particles was improved by varying the composition of electrolytic solutions. Platinum nanoparticles were deposited on electrode surfaces and the particle sizes were found to be larger than 10 nm and had

for a synthesis

ment was conducted at a constant current density of 25 mA cm<sup>−</sup><sup>2</sup>

#### *Preparation of Nanoparticles DOI: http://dx.doi.org/10.5772/intechopen.90771*

*Engineered Nanomaterials - Health and Safety*

Thermal decomposition also known as thermolysis is a chemical decomposition that is caused by heat. In this method, the heat is required to break chemical bonds in the compound undergoing decomposition and the reaction is endothermic. If decomposition is sufficiently exothermic, a positive feedback loop is created

Arshad et al. reported on thermal decomposition of metal complexes of type

DTG techniques in air atmosphere. They synthesized nitrate complexes of transition metals with 1,2-diimidazoloethane (DIE) of the general formula M(DIE) (NO3)2. The study was conducted by thermoanalytical techniques in static air atmosphere to study the thermal behavior of these complexes and to determine their mode of decomposition. The complexes and ligands decomposed in a two-step process when heated to 740°. Above 740°, the residue was found to correspond with metal oxide. The thermal stability of the complexes increases in the following series:

Patil et al. studied infrared spectra and thermal decompositions of metal acetates and dicarboxylates. The study was done to determine the metal-acetate bonding and the thermal decomposition of lead, copper, and rare earth acetates was studied by means of thermogravimetric analysis and differential thermal analysis.

George et al. reported on the mechanism of thermal decomposition of *n*-Buty l (tri-*n*-butylphosphine) copper (I). This study provided the first easily interpretable example in which succeeding reaction of a metal hydride and its parent metal alkyl was found to be vital in determining the products of a thermal decomposition [35]. Thermal decomposition of bismuth and silver carboxylates was investigated by means of TG, DSC, mass spectrometry, X-ray analysis, and electron microscopy Logvinenko et al. [36]. Non-isothermal thermogravimetric data were used for kinetic studies. All decomposition processes had multi-step character [36].

Ewell et al. investigated nearly pure talc both unheated and after heating at various temperatures ranging up to 1,435°C. The research included the measurement of heat effects, weight losses, and changes in true specific gravity occurring on heating talc. There was no change in the crystal structure of the talc heated up to 800°C. At the temperature between 800 and 8400°C, the talc decomposed to enstatite, amorphous silica, and water vapor. At the temperature approximately 1,200°C, the enstatite steadily changed to clinoenstatite and the amorphous silica changed to cristobalite approximately 1,300°C, giving clinoenstatite and cristobalite as end

Electrochemical synthesis is the synthesis of chemical compounds in an electrochemical cell. The main advantage of electrochemical synthesis over an ordinary chemical reaction is rejection of the potential wasteful alternative half-reaction and

Electrochemical synthesis of silver nanoparticles has been extensively studied in the previous years. The method of electrochemical that was used was based on the dissolution of a metallic anode in an aprotic solvent. The silver nanoparticles that were produced by electroreduction of anodically solved silver ions in acetonitrile containing tetrabutylammonium ranged from 2 to 7 nm. The particle size was obtained by varying the current density. Different types of counter electrodes were used to study the effect of the different electrochemical parameters on the

the ability to accurately tune the preferred potential [38].

The investigations on decomposition products yielded good results [34].

<sup>1</sup>*<sup>−</sup>*] by TG-DTA-

MLX2 [M = Co (II), Cu (II), Zn (II), and Cd (II);L = DIE; X = NO3

*2.1.3 Thermal decomposition*

producing thermal runaway [32].

Co(II) *<* Cu(II) *<* Zn(II) *<* Cd(II) [33].

**18**

products [37].

*2.1.4 Electrochemical synthesis*

end particle size. The UV-Vis spectra showed the presence of two different silver clusters [39].

Dobre et al. also reported on the electrochemical synthesis of colloidal silver solutions using "sacrificial anode" technique conducted with a home-built current pulse generator with alternating polarity and a stirrer. Poly (N-vinyl-2-pyrrolidone) (PVP) and sodium lauryl sulfate (Na-LS) were used as a stabilizer and co-stabilizer, correspondingly. Spherical Ag particles with the size approximately 10–55 nm were synthesized. The UV/Vis spectra showed the absorption band at 420 nm, which is the evidence of the presence of Ag nanoparticles. The zeta potential values between −17 and −35 mV suggested a presence of particles covered by stabilizer with a slight agglomeration [40].

More research was done on the electrochemical synthesis of silver nanoparticles in aqueous poly (vinyl alcohol) solution (PVA). PVA is a low price widely used synthetic polymer with properties such as nontoxicity, water solubility, biocompatibility, biodegradability, and excellent mechanical properties. The experiment was conducted at a constant current density of 25 mA cm<sup>−</sup><sup>2</sup> for a synthesis time of 10 min. Silver nanoparticles with an average diameter of 15 ± 9 nm were obtained [41].

The electrochemical synthesis of red fluorescent Silicon (Si) nanoparticles stabilized with styrene. Si nanoparticles emit fluorescence under UV excitation, which is great for optics applications, etc. It was found that the liberated silicon particles in ethanol solution interact with styrene, which resulted in the substitution of Si-H bonds with those of Si-C. The developed styrene-coated Si nanoparticles exhibited a stable, bright, red fluorescence under excitation with a 365 nm UV light, and resulted into approximately 100 mg per Si wafer with a synthesis time of 2 h [42].

More investigations were done on the preparation of long-lived silver nanoparticles in aqueous solutions and silver powders using electrochemical method. The produced silver nanoparticles had a size distribution ranging from 2 to 20 nm and the nanoparticles remained stable for more than 7 years. Silver crystals containing agglomerated silver nanoparticles with sizes below 40 nm was found growing on the surface of the cathode [43].

The research was conducted on using electrochemical method to synthesize highly pure silver nanoparticles. This method was used as it is one-step less expensive procedure and easy to control at room temperature and it does not use dangerous chemicals. The experimental setup brought up the oxidation of the anode and reduction of the cathode. The silver nanoparticles synthesized were spherical and had a particle size below 50 nm [44].

Islam et al. explored on the synthesis of platinum nanoparticles by electrochemical deposition method. The particle size was controlled by varying electrolysis parameters and homogeneity of platinum particles was improved by varying the composition of electrolytic solutions. Platinum nanoparticles were deposited on electrode surfaces and the particle sizes were found to be larger than 10 nm and had wide particle size distribution [45].

#### **2.2 Physical methods**

#### *2.2.1 Plasma*

Plasma method is another method that is used to produce nanoparticles. The plasma is generated by radio frequency (RF) heating coils. The initial metal is enclosed in a pestle and the pestle is enclosed in an evacuated chamber. The metal is then heated above its evaporation point by high voltage RF coils wrapped around the evacuated chamber. The gas that is used in the procedure is Helium (He), which forms a high-temperature plasma in the region of the coils after flowing into the system. The metal vapor nucleates on the helium gas atoms and diffuses up to a cold collector rod, this is where nanoparticles are collected and they are passivated by oxygen gas (**Figures 2** and **3**) [46].

Classification of plasma methods based on the feeding materials to reactor and also the heating source (electrodeless/ electrode containing), see (**Figures 2** and **3**).

#### *2.2.2 Chemical vapor deposition*

The chemical vapor deposition method (CVD) involves a chemical reaction. CVD procedure is mostly used in semiconductor manufacturing for depositing thin films of different materials. The method involves one or more volatile precursors, the substrate is exposed to those precursors that decompose on it and form the desired deposit. The vaporized precursors are inserted into a CVD reactor and adsorb onto a substance being placed at high temperature. The molecules that get adsorbed react with other molecules or decompose to form crystals. The three steps in CVD method are:


The CVD method can synthesize ultrafine particles of less than 1 μm by the chemical reaction taking place in the gaseous phase. The reaction can be controlled to produce nanoparticles of size ranging from 10 to 100 nm [46, 47].

#### *2.2.3 Microwave irradiation*

Microwave irradiation is a synthesis method that has been widely used in the synthesis of organic, inorganic, and inorganic–organic hybrid materials because of its well-known advantages over conventional synthetic routes [48].

A research was conducted on a rapid and efficient oxidation of organic compounds in microwave condition with new phase transfer oxidative agent: CTAMABC. CTMABC (1 mmole) was suspended in acetonitrile (2 ml) and an alcohol (l mmole in 0.5–1.5 ml of acetonitrile) was quickly added at room temperature and the resulting mixture was stirred vigorously. The mixture was then irradiated by microwave radiation (3.67 GHz, 300 W). The solution became homogeneous for a short time before the black-brown reduced reagent precipitated. Thin layer chromatography (TLC) and UV/VIS spectrophotometer (at 352 nm) were used to monitor the progress of reactions [49].

In another experiment conducted by Sahoo Biswa Mohan et al., o-Phenylenediamine (1.08 g, 0.01 mole) and anthranillic acid (1.37 g, 0.01mole) were dissolved in ethanol (15 ml). And K2CO3 was added to a mixture and the reaction mixture was put in microwave oven and refluxed at power (140 Watt) for 10 min. TLC was used to monitor the reaction. After the reaction was complete, ethanol was removed by distillation process and the residue was poured into crushed ice. Then the reaction was made alkaline by using 10% NaOH to get the solid product. The product was filtered, dried, and recrystallized from ethanol [50].

**21**

**Figure 3.**

**Figure 2.**

*in the case of expensive reaction or carrier gases.*

*Different plasma classification.*

Sahoo Biswa Mohan et al. conducted another experiment where N-(2-(1Hbenzo[d]imidazol-2-yl) phenyl) acetamide (2.51 g, 0.01 mole) was dissolved in ethanol (30 ml) and various aromatic aldehydes (0.01 mole) were taken and then an aqueous solution of KOH (2%, 5 ml) added to it. The reaction was then put in

*Flow diagram for production plant based on plasma burners. The recirculation system is of special importance* 

*Preparation of Nanoparticles*

*DOI: http://dx.doi.org/10.5772/intechopen.90771*

#### **Figure 2.**

*Engineered Nanomaterials - Health and Safety*

oxygen gas (**Figures 2** and **3**) [46].

*2.2.2 Chemical vapor deposition*

in CVD method are:

*2.2.3 Microwave irradiation*

monitor the progress of reactions [49].

filtered, dried, and recrystallized from ethanol [50].

forms a high-temperature plasma in the region of the coils after flowing into the system. The metal vapor nucleates on the helium gas atoms and diffuses up to a cold collector rod, this is where nanoparticles are collected and they are passivated by

Classification of plasma methods based on the feeding materials to reactor and also the heating source (electrodeless/ electrode containing), see (**Figures 2** and **3**).

The chemical vapor deposition method (CVD) involves a chemical reaction. CVD procedure is mostly used in semiconductor manufacturing for depositing thin films of different materials. The method involves one or more volatile precursors, the substrate is exposed to those precursors that decompose on it and form the desired deposit. The vaporized precursors are inserted into a CVD reactor and adsorb onto a substance being placed at high temperature. The molecules that get adsorbed react with other molecules or decompose to form crystals. The three steps

1.Reactants are transported on the growth surface by a boundary layer.

3.By products produced by the gas-phase reaction has to be removed from the surface. Homogeneous nucleation occurs in gas phase and heterogeneous

The CVD method can synthesize ultrafine particles of less than 1 μm by the chemical reaction taking place in the gaseous phase. The reaction can be controlled

Microwave irradiation is a synthesis method that has been widely used in the synthesis of organic, inorganic, and inorganic–organic hybrid materials because of

In another experiment conducted by Sahoo Biswa Mohan et al., o-Phenylenediamine (1.08 g, 0.01 mole) and anthranillic acid (1.37 g, 0.01mole) were dissolved in ethanol (15 ml). And K2CO3 was added to a mixture and the reaction mixture was put in microwave oven and refluxed at power (140 Watt) for 10 min. TLC was used to monitor the reaction. After the reaction was complete, ethanol was removed by distillation process and the residue was poured into crushed ice. Then the reaction was made alkaline by using 10% NaOH to get the solid product. The product was

A research was conducted on a rapid and efficient oxidation of organic compounds in microwave condition with new phase transfer oxidative agent: CTAMABC. CTMABC (1 mmole) was suspended in acetonitrile (2 ml) and an alcohol (l mmole in 0.5–1.5 ml of acetonitrile) was quickly added at room temperature and the resulting mixture was stirred vigorously. The mixture was then irradiated by microwave radiation (3.67 GHz, 300 W). The solution became homogeneous for a short time before the black-brown reduced reagent precipitated. Thin layer chromatography (TLC) and UV/VIS spectrophotometer (at 352 nm) were used to

to produce nanoparticles of size ranging from 10 to 100 nm [46, 47].

its well-known advantages over conventional synthetic routes [48].

2.Chemical reactions occur on the growth surface.

nucleation happens in a substrate.

**20**

*Flow diagram for production plant based on plasma burners. The recirculation system is of special importance in the case of expensive reaction or carrier gases.*

Sahoo Biswa Mohan et al. conducted another experiment where N-(2-(1Hbenzo[d]imidazol-2-yl) phenyl) acetamide (2.51 g, 0.01 mole) was dissolved in ethanol (30 ml) and various aromatic aldehydes (0.01 mole) were taken and then an aqueous solution of KOH (2%, 5 ml) added to it. The reaction was then put in

a microwave oven and refluxed at power (210 Watt) for 10–20 min. The excess solvent was removed by vacuum distillation and then poured into crushed ice and acidified with dilute HCl. The product was filtered, dried, and recrystallized from ethanol [51].

Microwave-assisted organic synthesis has been widely used due to enhanced reaction rates, higher yields, improved purity, ease of work up after the reaction and eco-friendly reaction conditions compared to the conventional methods. In above experiments, microwave irradiated synthesis of chalcone was carried out to get higher yield with less reaction time period as compared to conventional method.

The synthesized benzimidazolyl chalcone produces yield around 60% (conventional) and 80% (microwave) [52].

Another study was conducted to synthesize silver nanoparticles (AgNPs) in aqueous medium by a simple, efficient, and economic microwave-assisted synthetic route using hexamine as the reducing agent and the biopolymer pectin as stabilizer. The synthesized AgNPs were characterized by UV-VIS, Spectroscopy, Energy dispersive X-ray (EDX), X-ray diffraction (XRD), and Transmission electron microscopy (TEM) techniques. The nanoparticles were found to be spherical shape with an average diameter of 18.84 nm. The rate of reaction was found to increase with increasing temperature and the activation energy was found to be 47.3 kJ mol<sup>−</sup><sup>1</sup> [53].

ZnS nanoparticles were synthesized by microwave-assisted irradiation method. The produced ZnS nanoparticles were characterized by XRD, SEM, and UV-Vis spectroscopy. The average size of the nanocrystallites was measured by Debye-Scherrer formula as per the XRD spectrum, and there were found to be approximately 6 nm [54].

#### *2.2.4 Pulsed laser method*

Pulsed laser method is a method that is mostly used in the synthesis of silver nanoparticles, at a high rate of production of 3 gm/min. Silver nitrate solution and a reducing agent are poured into a blender-like device. The device is composed of a solid disc that rotates with the solution. The disc is exposed to pulses from a laser beam to create hot spots on the surface of the disc. Hot spots are where the silver nitrate reacts with reducing agent to produce silver particles that can be separated by centrifuge. The particle size is controlled by the energy of the laser and angular velocity of the disc [46] (**Figures 4** and **5**).

#### *2.2.5 Sonochemical reduction*

Sonochemical method has been studied in the synthesis of metal nanoparticles. The synthesis of different types of metal nanoparticles has been studied by use of the sonochemical reduction of the corresponding metal ions. The sonochemical reduction of MnO4−, Au3+, Au+ , and Pd2+ in the absence and presence of organic additives were investigated in relation to the synthesis of size and shape controlled metal nanoparticles. The rates of reduction were controlled to control the size and shape of metal nanoparticles. The size of the Au nanoparticles formed from the sonochemical reduction of Au3+ was controlled in the presence of an organic stabilizer citric acid [55].

Obreja et al. conducted a study on alcoholic reduction platinum nanoparticles synthesis by sonochemical reduction. H2PtCl6 was reduced with methanol, ethanol, and propanol working as solvents and reducing agents, in the presence of capping polymers such as chitosan, polyethylene glycol, and poly (amidehydroxyurethane). The produced nanoparticles size was found to be approximately 3 nm [56].

**23**

*Preparation of Nanoparticles*

*2.2.6 Gamma radiation*

shown in the following equation.

reducing agents e<sup>−</sup>

H2O ⇒ e

−

waste [57].

**Figure 5.**

*rotating disk [54].*

**Figure 4.**

Gamma radiation is the preferred method for metallic nanoparticles synthesis because it is reproducible, may control the shape of the particles yields monodisperse metallic nanoparticles, is easy, cheap, and use less toxins precursors: in water or solvents such as ethanol, it uses the least number of reagents, it uses a reaction temperature close to room temperature with as few synthetic steps as possible (one-pot reaction) and minimizing the quantities of generated by-products and

*Apparatus to produce silver nanoparticles using a pulsed laser beam that makes hot spots on the surface of a* 

The radiolytic reduction has been proven to be a powerful tool to fabricate monosized and highly dispersed metallic clusters [58]. The primary effects of the interaction of high-energy gamma photons with a solution of metal ions are the excitation and the ionization of the solvent [59]. The different reactions that are observed are well explained in the paper by Abidi and Remita. In particular, water can be produce upon irradiation of a series of reducing and oxidizing agents as

For the production of metallic nanoparticles from metallic salt solutions, the

the production of hydroxyl radicals OH• hampers the efficiency unless some

aq and H• are the cornerstones of the process. Unfortunately,

aq, H3O + ,H • ,OH • , H2, H2 O2 (1)

*DOI: http://dx.doi.org/10.5772/intechopen.90771*

*Synthesis of nanoparticles using a pulsed laser method [46].*

*Preparation of Nanoparticles DOI: http://dx.doi.org/10.5772/intechopen.90771*

**Figure 4.**

*Engineered Nanomaterials - Health and Safety*

tional) and 80% (microwave) [52].

[53].

ethanol [51].

47.3 kJ mol<sup>−</sup><sup>1</sup>

mately 6 nm [54].

*2.2.4 Pulsed laser method*

*2.2.5 Sonochemical reduction*

reduction of MnO4−, Au3+, Au+

stabilizer citric acid [55].

velocity of the disc [46] (**Figures 4** and **5**).

a microwave oven and refluxed at power (210 Watt) for 10–20 min. The excess solvent was removed by vacuum distillation and then poured into crushed ice and acidified with dilute HCl. The product was filtered, dried, and recrystallized from

Microwave-assisted organic synthesis has been widely used due to enhanced reaction rates, higher yields, improved purity, ease of work up after the reaction and eco-friendly reaction conditions compared to the conventional methods. In above experiments, microwave irradiated synthesis of chalcone was carried out to get higher yield with less reaction time period as compared to conventional method. The synthesized benzimidazolyl chalcone produces yield around 60% (conven-

Another study was conducted to synthesize silver nanoparticles (AgNPs) in aqueous medium by a simple, efficient, and economic microwave-assisted synthetic route using hexamine as the reducing agent and the biopolymer pectin as stabilizer. The synthesized AgNPs were characterized by UV-VIS, Spectroscopy, Energy dispersive X-ray (EDX), X-ray diffraction (XRD), and Transmission electron microscopy (TEM) techniques. The nanoparticles were found to be spherical shape with an average diameter of 18.84 nm. The rate of reaction was found to increase with increasing temperature and the activation energy was found to be

ZnS nanoparticles were synthesized by microwave-assisted irradiation method. The produced ZnS nanoparticles were characterized by XRD, SEM, and UV-Vis spectroscopy. The average size of the nanocrystallites was measured by Debye-Scherrer formula as per the XRD spectrum, and there were found to be approxi-

Pulsed laser method is a method that is mostly used in the synthesis of silver nanoparticles, at a high rate of production of 3 gm/min. Silver nitrate solution and a reducing agent are poured into a blender-like device. The device is composed of a solid disc that rotates with the solution. The disc is exposed to pulses from a laser beam to create hot spots on the surface of the disc. Hot spots are where the silver nitrate reacts with reducing agent to produce silver particles that can be separated by centrifuge. The particle size is controlled by the energy of the laser and angular

Sonochemical method has been studied in the synthesis of metal nanoparticles. The synthesis of different types of metal nanoparticles has been studied by use of the sonochemical reduction of the corresponding metal ions. The sonochemical

additives were investigated in relation to the synthesis of size and shape controlled metal nanoparticles. The rates of reduction were controlled to control the size and shape of metal nanoparticles. The size of the Au nanoparticles formed from the sonochemical reduction of Au3+ was controlled in the presence of an organic

Obreja et al. conducted a study on alcoholic reduction platinum nanoparticles synthesis by sonochemical reduction. H2PtCl6 was reduced with methanol, ethanol, and propanol working as solvents and reducing agents, in the presence of capping polymers such as chitosan, polyethylene glycol, and poly (amidehydroxyurethane).

The produced nanoparticles size was found to be approximately 3 nm [56].

, and Pd2+ in the absence and presence of organic

**22**

*Synthesis of nanoparticles using a pulsed laser method [46].*

#### **Figure 5.**

*Apparatus to produce silver nanoparticles using a pulsed laser beam that makes hot spots on the surface of a rotating disk [54].*

#### *2.2.6 Gamma radiation*

Gamma radiation is the preferred method for metallic nanoparticles synthesis because it is reproducible, may control the shape of the particles yields monodisperse metallic nanoparticles, is easy, cheap, and use less toxins precursors: in water or solvents such as ethanol, it uses the least number of reagents, it uses a reaction temperature close to room temperature with as few synthetic steps as possible (one-pot reaction) and minimizing the quantities of generated by-products and waste [57].

The radiolytic reduction has been proven to be a powerful tool to fabricate monosized and highly dispersed metallic clusters [58]. The primary effects of the interaction of high-energy gamma photons with a solution of metal ions are the excitation and the ionization of the solvent [59]. The different reactions that are observed are well explained in the paper by Abidi and Remita. In particular, water can be produce upon irradiation of a series of reducing and oxidizing agents as shown in the following equation.

$$\text{H}\_2\text{O} \Rightarrow \text{e}^-\text{}\_\text{aq}, \text{H}\_3\text{O} \ + \text{,} \text{H}\bullet, \text{OH} \ \bullet \text{,} \text{H}\_2, \text{H}\_2\text{O}\_2\tag{1}$$

For the production of metallic nanoparticles from metallic salt solutions, the reducing agents e<sup>−</sup> aq and H• are the cornerstones of the process. Unfortunately, the production of hydroxyl radicals OH• hampers the efficiency unless some

specific hydroxyl scavengers are used. Among them, isopropanol is frequently used [60].

This technique has been widely used so far to produce solutions of MNP primarily gold and silver that were further investigated by UV-Visible spectroscopy with the aim to analyze their plasmonic absorption band. A wealth of literature can be found on this topic [61, 62]. Additionally, γ rays irradiation was also used to trap MNP inside polymers or inside porous frameworks like mesoporous silica for instance [63–65].

#### **3. Conclusions**

Nanoparticles have gained significant interest due to their unique chemical and physical properties and are applicable to diverse areas. Various methods of preparation of nanoparticles have been developed and they are suitable for synthesis of nanoparticles in different sizes and shapes. The methods that were discussed include gamma irradiation, chemical reduction photochemical method, thermal decomposition, and microwave irradiation among others.

#### **Acknowledgements**

The author is particularly grateful to National Research Foundation, University of South Africa, iThemba LABS and L'Oreal For Women in Science for their support and funding.

#### **Author details**

Takalani Cele University of South Africa, Pretoria, South Africa

\*Address all correspondence to: tmadima@yahoo.com

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**25**

*Preparation of Nanoparticles*

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[3] Hirsch T, Zharnikov M, Shaporenko A, Stahl J, Weiss D, Wolfbeis OS, et al. Sizecontrolled electrochemical synthesis

monomolecular templates. Angewandte

## **References**

*Engineered Nanomaterials - Health and Safety*

used [60].

instance [63–65].

**3. Conclusions**

**Acknowledgements**

and funding.

specific hydroxyl scavengers are used. Among them, isopropanol is frequently

This technique has been widely used so far to produce solutions of MNP primarily gold and silver that were further investigated by UV-Visible spectroscopy with the aim to analyze their plasmonic absorption band. A wealth of literature can be found on this topic [61, 62]. Additionally, γ rays irradiation was also used to trap MNP inside polymers or inside porous frameworks like mesoporous silica for

Nanoparticles have gained significant interest due to their unique chemical and physical properties and are applicable to diverse areas. Various methods of preparation of nanoparticles have been developed and they are suitable for synthesis of nanoparticles in different sizes and shapes. The methods that were discussed include gamma irradiation, chemical reduction photochemical method, thermal

The author is particularly grateful to National Research Foundation, University of South Africa, iThemba LABS and L'Oreal For Women in Science for their support

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

decomposition, and microwave irradiation among others.

**24**

**Author details**

University of South Africa, Pretoria, South Africa

provided the original work is properly cited.

\*Address all correspondence to: tmadima@yahoo.com

Takalani Cele

[1] Adlim A. Review: Preparations and application of metal nanoparticles. Indonesian Journal of Chemistry. 2006;**6**(1):1-10

[2] Biswal J. A Study on Synthesis of Silver and Gold Nanoparticles by Employing Gamma Radiation, Their Characterization and Applications. Homi Bhabha National Institute; Department of Chemical Sciences; 2012. Available from: http://hdl.handle. net/10603/11458

[3] Hirsch T, Zharnikov M, Shaporenko A, Stahl J, Weiss D, Wolfbeis OS, et al. Sizecontrolled electrochemical synthesis of metal nano particles on monomolecular templates. Angewandte Chemie International Edition. 2005;**44**:6775-6778

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[13] Siemons M, Simon U. Gas sensing properties of volume-doped CoTiO3 synthesized via polyol method. Sensors and Actuators B: Chemical. 2007;**126**:595-603

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[15] Flores-Gonzalez MA, Ledoux G, Roux S, Lebboua K, Perriat P, Tillement O. Preparing nanometer scaled Tb-doped Y2O3 luminescent powders by the polyol method. Journal of Solid State Chemistry. 2005;**178**:989-997

[16] Jiang XC, Herricks T, Xia YN. Monodispersed spherical colloids of titania: Synthesis, characterization, and crystallization. Advanced Materials. 2003;**15**:1205-1209

[17] Sun YG, Yin YD, Mayers BT, Herricks T, Xia YN. Uniform silver nanowires synthesis by reducing AgNO3 with ethylene glycol in the presence of seeds and poly(vinyl pyrrolidone). Chemistry of Materials. 2002;**14**:4736-4745

[18] Bonet F, Grugeon S, Dupont L, Herrera Urbina R, Guery C, Tarascon J. Synthesis and characterization of bimetallic Ni–Cu particles. Journal of Solid State Chemistry. 2003;**172**:111

[19] Tekaia-Elhsissen K, Bonet F, Silvert P-Y, Herrera-Urbina R. Finely divided platinum–gold alloy powders prepared in ethylene glycol. Journal of Alloys and Compounds. 1999;**292**(1-2):96-99

[20] Garcia-Gutierrez D, Gutierrez-Wing CE, Giovanetti L, Ramallo-Lopez JM, Requejo FG, Jose-Yacaman M. Temperature effect on the synthesis of Au-Pt bimetallic nanoparticles. The Journal of Physical Chemistry B. 2005;**109**:3813-3821

[21] Kim F, Connor S, Song H, Kuykendall T, Yang P. Platonic gold nanocrystals. Angewandte Chemie, International Edition. 2004;**43**(28):3673-3677

[22] Wiley B, Sun Y, Mayers B, Xia Y. Shaped-controlled synthesis of metal nanostructure: The case of silver. Chemistry—A European Journal. 2005;**11**:454-463

[23] Tauer K. MPI Colloids and Interfaces, Emulsions Part 1, Am Mühlenberg, D-14476 Golm, Germany

[24] Yu D, Chu Y, Dong LH, Zhuo YJ. Controllable synthesis of CaCO3 micro/nanocrystals with

different morphologies in microemulsion. Chemical Research in Chinese Universities. 2010;**26**:678

[25] Capek I. Radical polymerization of polar unsaturated monomers in direct microemulsion systems. Advances in Colloid and Interface Science. 1999;**80**(2):85-149

[26] Holmberg K. Handbook of Applied Surface and Colloid Chemistry. Chichester, New York: Wiley; 2002

[27] Zielińska-Jurek A, Reszczyńska J, Grabowska E, Zaleska A. Nanoparticles Preparation Using Microemulsion Systems. Poland: Gdansk University of Technology; 2011

[28] Bönnemann H, Richards RM. Nanoscopic metal particles - synthetic methods and potential applications. Carboxylates, physical basis of radiation-related technologies. European Journal of Inorganic Chemistry. 2001;**2001**(10):2455-2480

[29] Wongwailikhit K, Horwongsakul S. The preparation of iron (III) oxide nanoparticles using W/O microemulsion. Materials Letters. 2011;**65**:2820-2822

[30] Sarkar D, Tikku S, Thapar V, Srinivasa RS, Khilar KC. Formation of zinc oxide nanoparticles of different shapes in water-in-oil microemulsion. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2011;**381**:123-129

[31] Maitra AN, et al. Process for the preparation of highly monodispersed hydrophilic polymeric nanoparticles of size less than 100 nm. US Patent 5874111; 1999

[32] https://en.wikipedia.org/wiki/ Thermal\_decomposition [Accessed: April 2016]

[33] Arshad M, Rehman S, Quresh AH, Masud K, Arif M, Saeed A, et al.

**27**

*Preparation of Nanoparticles*

X = NO3

1970;**92**:1426

April 2016]

2000;**104**:9683-9688

*DOI: http://dx.doi.org/10.5772/intechopen.90771*

1−) by TG-DTA-DTG techniques

Serbian Chemical Society. 2013;**78**(12):2087-2098

2014;**35**(1):35-38

2009;**11**:1193-1200

2014;**28**(2):272-277

2016]

[42] Choi J, Kim K, Han H, Hwang MP, Lee KH. Electrochemical synthesis of red fluorescent silicon nanoparticles. Bulletin of the Korean Chemical Society.

[43] Khaydarov RA, Khaydarov RR, Gapurova O, Estrin Y, Scheper T. Electrochemical method for the synthesis of silver nanoparticles. The Journal of Nanoparticle Research.

[44] Sharma S, Choudhary K, Singhal I, Saini R. Synthesis of silver nanoparticles by 'electrochemical route' through pure metallic silver electrodes, and evaluation of their antimicrobial activities. International Journal of Pharmaceutical Sciences and Research.

[45] Islam AM, Islam MS. Electrodeposition method for platinum nanoparticles synthesis. Engineering

International, Asian Business Consortium. 2013;**1**(2):9

[46] http://shodhganga.inflibnet. ac.in/bitstream/10603/21144/10/10\_ chapter%203.pdf [Accessed: April

[47] Khah V, Sara D, Djafar IR, Rahman N, Jafar IR. Aglance on the plasma synthesis methodologies of the nanoparticles. In: Proceedings of the Sixth NanoEurope Congress and Exhibition; St. Gallen, Switzeland; 2008

[48] Horikoshi S, Serpone N. Introduction

to Nanoparticles, Microwaves in Nanoparticle Synthesis. 1st ed: Wiley-VCH Verlag GmbH & Co. KGaA; 2013

[49] Riaz U, Ashraf SM, Madan A. Effect of microwave irradiation time and temperature on the spectroscopic and morphological properties of nanostructured poly(carbazole)

Thermal decomposition of metal complexes of type MLX2 (M = Co(II), Cu(II), Zn(II), and Cd(II); L = DIE;

in air atmosphere. Turkish Journal of

[34] Patil KC, Chandrashekhmar GV, George MV, Rao CNR. Infrared spectra and thermal decompositions of metal acetates and dicarboxylates. Canadian Journal of Chemistry. 1968;**46**:257

[35] Whitesides GM, Stedronsky ER, Casey CP, Filippo J. Mechanism of thermal decomposition of *n*-buty l (tri*n*-buty lphosphine) coppe r(I). Journal of the American Chemical Society.

[36] Logvinenko V, Mikhailov YV, Polunina OS, Mikhailov K, Minina AV, Yukhin YM. Pecularities of the thermal

decomposition of bismuth and silver carboxylates. In: Proceedings, Logvinenko2006PecularitiesOT; 2006

Standards. 1935;**15**:551-556

[37] Ewell RH, Bunting EN, Geller RF. Thermal decomposition of talc. Journal of Research of the National Bureau of

[38] https://en.wikipedia.org/wiki/ electrochemical synthesis [Accessed:

[40] Dobre N, Petica A, Buda M, Anicai L, Visan T. Electrochemical synthesis of silver nanoparticles in aqueous electrolytes. UPB Scientific Bulletin, Series B. 2014;**76**(4):1454-2331

[41] Surudzic R, Jovanovic Z,

Electrochemical synthesis of silver nanoparticles in poly(vinyl alcohol) solution. Journal of the

Bibic N, Nikolic B, Miskovic-Stankovic V.

[39] Rodriguez-Sanchez L, Blanco MC, Lopez-Quintela MA. Electrochemical synthesis of silver nanoparticles. The Journal of Physical Chemistry B.

Chemistry. 2008;**32**:593-604

#### *Preparation of Nanoparticles DOI: http://dx.doi.org/10.5772/intechopen.90771*

*Engineered Nanomaterials - Health and Safety*

different morphologies in

1999;**80**(2):85-149

Technology; 2011

microemulsion. Chemical Research in Chinese Universities. 2010;**26**:678

[25] Capek I. Radical polymerization of polar unsaturated monomers in direct microemulsion systems. Advances in Colloid and Interface Science.

[26] Holmberg K. Handbook of Applied

[27] Zielińska-Jurek A, Reszczyńska J, Grabowska E, Zaleska A. Nanoparticles Preparation Using Microemulsion Systems. Poland: Gdansk University of

[28] Bönnemann H, Richards RM. Nanoscopic metal particles - synthetic methods and potential applications. Carboxylates, physical basis of radiation-related technologies. European Journal of Inorganic Chemistry. 2001;**2001**(10):2455-2480

[29] Wongwailikhit K, Horwongsakul S.

The preparation of iron (III) oxide nanoparticles using W/O microemulsion. Materials Letters.

[30] Sarkar D, Tikku S, Thapar V, Srinivasa RS, Khilar KC. Formation of zinc oxide nanoparticles of different shapes in water-in-oil microemulsion. Colloids and Surfaces A: Physicochemical and Engineering

[31] Maitra AN, et al. Process for the preparation of highly monodispersed hydrophilic polymeric nanoparticles of size less than 100 nm. US Patent

[32] https://en.wikipedia.org/wiki/ Thermal\_decomposition [Accessed:

[33] Arshad M, Rehman S, Quresh AH, Masud K, Arif M, Saeed A, et al.

Aspects. 2011;**381**:123-129

5874111; 1999

April 2016]

2011;**65**:2820-2822

Surface and Colloid Chemistry. Chichester, New York: Wiley; 2002

[16] Jiang XC, Herricks T, Xia YN. Monodispersed spherical colloids of titania: Synthesis, characterization, and crystallization. Advanced Materials.

[17] Sun YG, Yin YD, Mayers BT, Herricks T, Xia YN. Uniform silver nanowires synthesis by reducing AgNO3 with ethylene glycol in the presence of seeds and poly(vinyl pyrrolidone). Chemistry of Materials.

[18] Bonet F, Grugeon S, Dupont L, Herrera Urbina R, Guery C, Tarascon J. Synthesis and characterization of bimetallic Ni–Cu particles. Journal of Solid State Chemistry. 2003;**172**:111

[19] Tekaia-Elhsissen K, Bonet F, Silvert P-Y, Herrera-Urbina R. Finely divided platinum–gold alloy powders prepared in ethylene glycol. Journal of Alloys and Compounds. 1999;**292**(1-2):96-99

[20] Garcia-Gutierrez D, Gutierrez-

Ramallo-Lopez JM, Requejo FG, Jose-Yacaman M. Temperature effect on the synthesis of Au-Pt bimetallic nanoparticles. The Journal of Physical Chemistry B. 2005;**109**:3813-3821

[21] Kim F, Connor S, Song H, Kuykendall T, Yang P. Platonic gold

[22] Wiley B, Sun Y, Mayers B, Xia Y. Shaped-controlled synthesis of metal nanostructure: The case of silver. Chemistry—A European Journal.

[23] Tauer K. MPI Colloids and Interfaces, Emulsions Part 1, Am Mühlenberg, D-14476 Golm, Germany

[24] Yu D, Chu Y, Dong LH, Zhuo YJ. Controllable synthesis of CaCO3 micro/nanocrystals with

nanocrystals. Angewandte Chemie, International Edition.

2004;**43**(28):3673-3677

2005;**11**:454-463

Wing CE, Giovanetti L,

2003;**15**:1205-1209

2002;**14**:4736-4745

**26**

Thermal decomposition of metal complexes of type MLX2 (M = Co(II), Cu(II), Zn(II), and Cd(II); L = DIE; X = NO3 1−) by TG-DTA-DTG techniques in air atmosphere. Turkish Journal of Chemistry. 2008;**32**:593-604

[34] Patil KC, Chandrashekhmar GV, George MV, Rao CNR. Infrared spectra and thermal decompositions of metal acetates and dicarboxylates. Canadian Journal of Chemistry. 1968;**46**:257

[35] Whitesides GM, Stedronsky ER, Casey CP, Filippo J. Mechanism of thermal decomposition of *n*-buty l (tri*n*-buty lphosphine) coppe r(I). Journal of the American Chemical Society. 1970;**92**:1426

[36] Logvinenko V, Mikhailov YV, Polunina OS, Mikhailov K, Minina AV, Yukhin YM. Pecularities of the thermal decomposition of bismuth and silver carboxylates. In: Proceedings, Logvinenko2006PecularitiesOT; 2006

[37] Ewell RH, Bunting EN, Geller RF. Thermal decomposition of talc. Journal of Research of the National Bureau of Standards. 1935;**15**:551-556

[38] https://en.wikipedia.org/wiki/ electrochemical synthesis [Accessed: April 2016]

[39] Rodriguez-Sanchez L, Blanco MC, Lopez-Quintela MA. Electrochemical synthesis of silver nanoparticles. The Journal of Physical Chemistry B. 2000;**104**:9683-9688

[40] Dobre N, Petica A, Buda M, Anicai L, Visan T. Electrochemical synthesis of silver nanoparticles in aqueous electrolytes. UPB Scientific Bulletin, Series B. 2014;**76**(4):1454-2331

[41] Surudzic R, Jovanovic Z, Bibic N, Nikolic B, Miskovic-Stankovic V. Electrochemical synthesis of silver nanoparticles in poly(vinyl alcohol) solution. Journal of the

Serbian Chemical Society. 2013;**78**(12):2087-2098

[42] Choi J, Kim K, Han H, Hwang MP, Lee KH. Electrochemical synthesis of red fluorescent silicon nanoparticles. Bulletin of the Korean Chemical Society. 2014;**35**(1):35-38

[43] Khaydarov RA, Khaydarov RR, Gapurova O, Estrin Y, Scheper T. Electrochemical method for the synthesis of silver nanoparticles. The Journal of Nanoparticle Research. 2009;**11**:1193-1200

[44] Sharma S, Choudhary K, Singhal I, Saini R. Synthesis of silver nanoparticles by 'electrochemical route' through pure metallic silver electrodes, and evaluation of their antimicrobial activities. International Journal of Pharmaceutical Sciences and Research. 2014;**28**(2):272-277

[45] Islam AM, Islam MS. Electrodeposition method for platinum nanoparticles synthesis. Engineering International, Asian Business Consortium. 2013;**1**(2):9

[46] http://shodhganga.inflibnet. ac.in/bitstream/10603/21144/10/10\_ chapter%203.pdf [Accessed: April 2016]

[47] Khah V, Sara D, Djafar IR, Rahman N, Jafar IR. Aglance on the plasma synthesis methodologies of the nanoparticles. In: Proceedings of the Sixth NanoEurope Congress and Exhibition; St. Gallen, Switzeland; 2008

[48] Horikoshi S, Serpone N. Introduction to Nanoparticles, Microwaves in Nanoparticle Synthesis. 1st ed: Wiley-VCH Verlag GmbH & Co. KGaA; 2013

[49] Riaz U, Ashraf SM, Madan A. Effect of microwave irradiation time and temperature on the spectroscopic and morphological properties of nanostructured poly(carbazole)

synthesized within bentonite clay galleries. New Journal of Chemistry. 2014;**38**:4219-4228

[50] Mohammadib M, Imanieha H, Ghammamya S. Rapid and efficient oxidation of organic compounds in microwave condition with new phase transfer oxidative agent: CTAMABC; 2008. DOI: 10.3390/ecsoc-12-01260

[51] Mohan SB, Behera TP, Kumar BVVR. Microwave irradiation versus conventional method: Synthesis of benzimidazolyl chalcone derivatives. International Journal of ChemTech Research. 2010;**2**(3):1634-1637

[52] Joseph S, Mathew B. Synthesis of silver nanoparticles by microwave irradiation and investigation of their catalytic activity. Research Journal of Recent Sciences. 2014;**3**:185-191

[53] Tiwary KP, Choubey SK, Sharma K. Structural and optical properties of ZnS nanoparticles synthesized by microwave irradiation method. Chalcogenide Letters. 2013;**10**(9):319-323

[54] Singh J. Materials Today 2, 2001:10

[55] Okitsu K, Nishimura R. Sonochemical reduction method for controlled synthesis of metal nanoparticles in aqueous solutions. In: Proceedings of 20th International Congress on Acoustics, ICA 2010;23-27. August 2010; Sydney, Australia; 2010

[56] Obreja L, Foca N, Popa MI, Melnig V. Alcoholic reduction platinum nanoparticles, synthesis by sonochemical method, biomaterials in biophysics. Medical Physics and Ecology. 2008:31-36

[57] Rao YN, Banerjee D, Datta A, Das S|K, Guin R, Saha A. Gamma irradiation route to synthesis of highly re-dispersible natural polymer capped silver nanoparticles. Radiation Physics and Chemistry. 2010;**79**:1240-1246

[58] Marignier J, Belloni J, Delcourt M, Chevalier J. New microaggregates of non noble metals and alloys prepared by radiation induced reduction. Nature. 1985;**317**:344-345

[59] Abidi W, Remita H. Gold based nanoparticles generated by radiolytic and photolytic methods. Recent Patents on Engineering. 2010, 2010;**4**(3):170-188

[60] Temgire MK, Bellare J, Joshi SS. Gamma radiolytic formation of alloyed Ag-Pt nanocolloids. Advances in Physical Chemistry. 2011; 9 p. Article ID: 249097

[61] Jayashree B, Ramnani SP, Tewari R. Short aspect ratio gold nanorods prepared using gamma radiation in the presence of cetyltrimethyl ammonium bromide (CTAB) as a directing agent. Radiation Physics and Chemistry. 2010;**79**(4):441-445

[62] Gachard E, Remita H, Khatouri J, Keita B, Nadjo L, Belloni J. Radiationinduced and chemical formation of gold clusters. New Journal of Chemistry. 1998;**22**(11):1257-1265

[63] Krklješ A. Radiolytic synthesis of nanocomposites based on noble metal nanoparticles and natural polymer, and their application as biomaterial (IAEA-RC--12071). International Atomic Energy Agency (IAEA); 2011

[64] Chen Q, Shi J, Zhao R, Shen X. Radiolytic syntheses of nanoparticles and inorganic-polymer hybrid microgels (IAEA-RC--11242). International Atomic Energy Agency (IAEA); 2010

[65] Hornebecq V, Antonietti M, Cardinal T, Treguer-Delapierre M. Stable silver nanoparticles immobilized in mesoporous silica. Chemistry of Materials. 2003;**15**(10):1993-1999

**29**

**Chapter 3**

**Abstract**

research practice.

**1. Introduction**

*and Jana Soukupova*

Physicochemical Aspects of Metal

Physicochemical properties, including optical properties or catalytic activity, and biological properties of metal nanoparticles are considerably influenced by their diameter. Therefore, a tailored synthesis of metal nanoparticles represents a key topic in the field of nanotechnology, and the number of research papers, concerning this topic, has been annually growing with an arithmetic progression. Metal nanoparticles are most frequently prepared via chemical reduction of metals in ionic form from their solutions. Using this synthetic approach, tailored parameters of the particles can be achieved via the adjustment of numerous factors: difference of potentials of the metal redox system and the reducing agent redox system, pH of the reaction mixture, and its temperature. The influence of these three factors on the diameter of the prepared metal nanoparticles will be discussed in the following chapter with respect to general laws and based on numerous examples from

**Keywords:** metal nanoparticles, tailored preparation, size distribution,

Metal nanoparticles can be classified among the most studied nanomaterials due to their numerous potential applications [1–3]. Silver and gold nanoparticles have found their targeted applications in the enhancement of Raman scattering due to the optical properties that are associated with the existence of localized surface plasmon resonance (LSPR) [4–8] with the absorption maximum in visible part of the electromagnetic part of the spectra. Thanks to this fact the particles provide a significant enhancement of the Raman signal used in the highly sensitive analytical method of surface-enhanced Raman spectroscopy (SERS) [9–12] used in biology and medicine [13–17]. Transitional metals are commonly known for their high catalytic activity, which is even amplified by the nanodimension of the metal nanoparticles with high ratio between the surface area and the volume of the particle because the catalytic process is located on the surface [18–20]. From the application point of view, even the magnetic behavior of the metal nanoparticles must be taken into account [21, 22]. Last, but not least, the biological activity of the metal nanoparticles must be mentioned, especially in the case of the silver nanoparticles [23–25]. These particles became one of the phenomena of nanotechnology. Recently, more and more products of everyday usage involve

chemical reduction, redox potential, pH, temperature

Nanoparticle Preparation

*Libor Kvitek, Robert Prucek, Ales Panacek* 

#### **Chapter 3**

*Engineered Nanomaterials - Health and Safety*

[58] Marignier J, Belloni J, Delcourt M, Chevalier J. New microaggregates of non noble metals and alloys prepared by radiation induced reduction. Nature.

[59] Abidi W, Remita H. Gold based nanoparticles generated by radiolytic and photolytic methods. Recent Patents on Engineering. 2010,

[60] Temgire MK, Bellare J, Joshi SS. Gamma radiolytic formation of alloyed Ag-Pt nanocolloids. Advances in Physical Chemistry. 2011; 9 p. Article

[61] Jayashree B, Ramnani SP, Tewari R. Short aspect ratio gold nanorods prepared using gamma radiation in the presence of

2010;**79**(4):441-445

1998;**22**(11):1257-1265

cetyltrimethyl ammonium bromide (CTAB) as a directing agent. Radiation Physics and Chemistry.

[62] Gachard E, Remita H, Khatouri J, Keita B, Nadjo L, Belloni J. Radiationinduced and chemical formation of gold clusters. New Journal of Chemistry.

[63] Krklješ A. Radiolytic synthesis of nanocomposites based on noble metal nanoparticles and natural polymer, and their application as biomaterial (IAEA-RC--12071). International Atomic Energy Agency (IAEA); 2011

[64] Chen Q, Shi J, Zhao R, Shen X. Radiolytic syntheses of nanoparticles and inorganic-polymer hybrid microgels (IAEA-RC--11242). International Atomic Energy Agency (IAEA); 2010

[65] Hornebecq V, Antonietti M, Cardinal T, Treguer-Delapierre M. Stable silver nanoparticles immobilized in mesoporous silica. Chemistry of Materials. 2003;**15**(10):1993-1999

1985;**317**:344-345

2010;**4**(3):170-188

ID: 249097

synthesized within bentonite clay galleries. New Journal of Chemistry.

[50] Mohammadib M, Imanieha H, Ghammamya S. Rapid and efficient oxidation of organic compounds in microwave condition with new phase transfer oxidative agent: CTAMABC; 2008. DOI: 10.3390/ecsoc-12-01260

Kumar BVVR. Microwave irradiation versus conventional method: Synthesis of benzimidazolyl chalcone derivatives. International Journal of ChemTech Research. 2010;**2**(3):1634-1637

[52] Joseph S, Mathew B. Synthesis of silver nanoparticles by microwave irradiation and investigation of their catalytic activity. Research Journal of Recent Sciences. 2014;**3**:185-191

[53] Tiwary KP, Choubey SK, Sharma K. Structural and optical properties of ZnS nanoparticles synthesized by microwave irradiation method. Chalcogenide Letters. 2013;**10**(9):319-323

[54] Singh J. Materials Today 2, 2001:10

[55] Okitsu K, Nishimura R. Sonochemical reduction method for controlled synthesis of metal nanoparticles in aqueous solutions. In: Proceedings of 20th International Congress on Acoustics, ICA 2010;23-27. August 2010; Sydney, Australia; 2010

[56] Obreja L, Foca N, Popa MI,

nanoparticles, synthesis by

route to synthesis of highly

Ecology. 2008:31-36

Melnig V. Alcoholic reduction platinum

sonochemical method, biomaterials in biophysics. Medical Physics and

[57] Rao YN, Banerjee D, Datta A, Das S|K, Guin R, Saha A. Gamma irradiation

re-dispersible natural polymer capped silver nanoparticles. Radiation Physics and Chemistry. 2010;**79**:1240-1246

[51] Mohan SB, Behera TP,

2014;**38**:4219-4228

**28**
