Biomedical Applications of Silver Nanoparticles

*Manikandan Dhayalan, Priadharsini Karikalan, Mohammed Riyaz Savaas Umar and Nalini Srinivasan*

#### **Abstract**

Nanotechnology is a branch of science and engineering dedicated to materials, having dimensions in the order of nanometer scale and it has been widely used for the development of more efficient technology. Nanoparticles offer many benefits to bulk particles such as increased surface-to-volume ratio, and increased magnetic properties. In recent years, nanotechnology has been embraced by industrial sectors due to its applications in the field of electronic storage systems, biotechnology, magnetic separation and pre concentration of target analytes, targeted drug delivery, and vehicles for gene and drug delivery. Over the year's nanomaterials such as nanoparticles, nanoclusters, nanoreods, nanoshells, and nanocages have been continuously used and modified to enable their use as a diagnostic and therapeutic agent in biomedical applications. Thus, In this chapter, introduction to metal nanoparticles, synthesis (Chemical and green synthesis) and biomedical application silver nanoparticles are presented.

**Keywords:** Green Synthesis, Metal Nanoparticles , Silver nanoparticles , Biomedical Applications

#### **1. Introduction**

The trend of miniaturization combined with technological modernization requirements has led to the substantial rise in exploring nanoparticles. The discoveries of new antibiotics, conventional drugs and chemically modified drugs can not only resolve the microbial resistant issues but also necessitates a prolonged effective metallic nanotechnology in diverse applications. Nanomaterials such as nanoparticles, nanoclusters, nanorods, nanoshells, and nanocages are modified constantly to enable their use as a diagnostic and therapeutic agents applications. Theefficacy of the nanoparticle can be determined by its size, structure, concentration, dimensions and ionic strength accompanied with surface coating can support additional strength and durability as a carrier for a wide range of therapeutic components in several biomedical applications. Nanoparticles offer various benefits to bulk particles with increased surfaceto-volume ratio, magnetictarget [1, 2], wound healing properties [3], biocomposite preparation, gene and drug delivery vehicles [1, 2, 4].

Nanoparticles synthesis and characterization have flourished due to their wideranging applicability particularly as catalysts in biomedical, optics, and energy fields [5]. Among the classified nanoparticles, metalnanoparticles have fascinated, due to their distinctive physical and chemical properties, selectivity, highly active, and reproducibility. Among different metal nanoparticles, silver nanoparticles (AgNPs) have attracted considerable researcher's attention because of its high electrical

and thermal conductivity, surface-enhanced Raman scattering, chemical stability, catalytic activity and antimicrobial activity [6, 7]. Silver nanoparticles are increasingly being applied in biomedicines for their respective broad antimicrobial behavior becoming more attractive for use in drug delivery and targeting especially for their tunable hydrophilic - hydrophobic balance and target specific localization surface features as versatile opportunities in drug delivery and modification systems [6, 7]. The above mentioned properties have enabled silver nanoparticles to serve as a material in the development of new generation electronic, optical and sensor devices.

#### **2. Synthesis of metal nanoparticles**

In the synthesis of nano materials, particularly metallic nanoparticles, has raised greatest attention over the past decade due to their exclusiveproperty that make them suitable in various fields of science and technology. There is a scarcity of effective methods to synthesis a homogeneous size and shape nanoparticles with limited or no toxicity to the human health and the environment. There are two methods for the synthesis of metallic nanoparticles- top-down and bottom-up approaches [8]. In bottom-up approach, reduction of materials components with further self-assembly process which leads to the formation of nanostructures. Representative examples include Quantum dot and formation of nanoparticles from colloidal dispersion. In Top down approach [9] includes the macroscopic structures which can be externally controlled in the processing of nanostructures, such as ball milling, application of severe plastic deformation [10].

#### **3. Chemical synthesis/green synthesis of metal nanoparticles**

Even though nanoparticles can be made using various physicochemical methods their synthesis using nontoxic and environmentally kind biological methods is attractive specially. The biological method (green synthesis) is comparatively easy, economical, and environmentally affable method than the conventional chemical method of synthesis and thus accomplish an upper hand. Numerous studies have shown that characteristics of metallic nanoparticles such as size, stability, physical, chemical properties and morphology are strongly influenced by the experimental conditions. Several routes have been developed for biological or biogenic synthesis of nanoparticles from salts of the corresponding metals [11–14]. Microorganisms, whole plants, plant tissue and fruits, plant extracts and marine algae [15] have been used to synthesis nanoparticles.

Plants are regarded as a highly desirable system for nanoparticle synthesis due to their tremendous capability to produce a broad range of bioactive secondary metabolites with profound reducing potential. As compared to bacteria and algae and, plants are less vulnerable to metal toxicity, thus offering a green substitute for the biosynthesis of metal nanoparticles [16].

#### **4. Green synthesis of silver nanoparticles using leaf, seed, fruit, bark and their potential**

Among all metal nanoparticles, silver nanoparticles are of great significance in the field of nanotechnology [17]. Nanoparticles are synthesized by physical, chemical, and biological or green methods. Various chemical and physical methods are proved to be quite expensive and the use of various toxic chemicals that are responsible for various biological risks. This may be the reason for choosing biosynthesis of nanoparticles via green routethat does not employ toxic chemicals and

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Silver ions (Ag+

**7. Antibacterial**

*Biomedical Applications of Silver Nanoparticles DOI: http://dx.doi.org/10.5772/intechopen.99367*

ent organisms in different ways.

proved to be eco-friendly [18]. Silver nanoparticles are the most prototypical target of green methods [19–23] and can be synthesized using plant extracts.Gold and silver metal nanoparticles weregreen synthesized using the Root Extract of Coleous

Silver nanoparticles have diverted the attention of the scientific community and industrialist itself due to their wide range of applications in industry for the preparation of consumer products and highly accepted application in biomedical fields. Silver has function in antimicrobial, catalytic and biological systems and the unique physical and chemical properties of silver nanoparticles only increase the efficacy of silver. Though there are many mechanisms ascribed to the antimicrobial activity shown by silver nanoparticles, the actual and most reliable mechanism is not fully understood or cannot be generalized as the nanoparticles are found to act on differ-

During the past few years, silver nanoparticles became one of the most examined and explored nanotechnology-derived nanostructures, given the fact that silver nanoparticles proved to have interesting, challenging, and promising characteristics suitable for various biomedical applications [25]. Even though there is limited information regarding the toxicity and in vivo biological behavior, these nanostructures were used for a long time as antibacterial agents in the health industry cosmetics,

The exclusiveproperty of silver nanoparticles areparticularly advantageous for cancer therapeutics since they led to an improved chemotherapeutic efficiency together with minimal systemic toxicity [27]. AgNPs attracted special attention for this particular domain, and were successfully evaluated as effective anti-tumor drug-delivery systems [28], acting either as passive [29] or active [30] nanocarriers for anticancer drugs. Recent studies evidenced the potential use of AgNPs as vaccine and drug carriers for specific and selective cell or tissue targeting [31]. In addition tothe great optical properties of AgNPs [32–34] the recent improvements in AgNP biocompatibility and stability viasurface modification strongly recommend nanostructured systems based on silver as specific, selective,and versatile candidates for drug-delivery applications [35].

Researches on the synthesis of silver nanoparticles using microbes and plant extract has become active due to its easy accessibility, non-toxicity, wide ranged applications, flexibility and essentially for its biodegradability, sustainability and cost effectivity. Various plants are being effectively used for the synthesis of metal nanoparticles. Various plant parts including fruit peels, leaves, barks, flowers, roots are used in synthesizing silver and other metal nanoparticles. Silver nanoparticles can serve as a medium for the delivery of antibiotics and disinfecting materials.

Silver has been found in our traditional medicines and culinary for a long time. Silver is known to cause bacteriostatic (growth inhibition) and bactericidal (eradicate) properties, hence described as oligodynamic it is metals enclose ions that devastate

) and their respective compounds are highly toxic to broad spectral

food storage, textile coatings and some environmental applications [26].

**6. Silver nanoparticles as antimicrobial agents**

microorganisms. As a biological approach, different plants.

forskohlii as capping and reducing agent for biomedical applications [24].

**5. Biomedical application of silver nanoparticles**

*Silver Micro-Nanoparticles - Properties, Synthesis, Characterization, and Applications*

**2. Synthesis of metal nanoparticles**

milling, application of severe plastic deformation [10].

the biosynthesis of metal nanoparticles [16].

**and their potential**

**3. Chemical synthesis/green synthesis of metal nanoparticles**

Even though nanoparticles can be made using various physicochemical methods their synthesis using nontoxic and environmentally kind biological methods is attractive specially. The biological method (green synthesis) is comparatively easy, economical, and environmentally affable method than the conventional chemical method of synthesis and thus accomplish an upper hand. Numerous studies have shown that characteristics of metallic nanoparticles such as size, stability, physical, chemical properties and morphology are strongly influenced by the experimental conditions. Several routes have been developed for biological or biogenic synthesis of nanoparticles from salts of the corresponding metals [11–14]. Microorganisms, whole plants, plant tissue and fruits, plant extracts and marine algae [15] have been used to synthesis nanoparticles. Plants are regarded as a highly desirable system for nanoparticle synthesis due to their tremendous capability to produce a broad range of bioactive secondary metabolites with profound reducing potential. As compared to bacteria and algae and, plants are less vulnerable to metal toxicity, thus offering a green substitute for

**4. Green synthesis of silver nanoparticles using leaf, seed, fruit, bark** 

Among all metal nanoparticles, silver nanoparticles are of great significance in the field of nanotechnology [17]. Nanoparticles are synthesized by physical, chemical, and biological or green methods. Various chemical and physical methods are proved to be quite expensive and the use of various toxic chemicals that are responsible for various biological risks. This may be the reason for choosing biosynthesis of nanoparticles via green routethat does not employ toxic chemicals and

and thermal conductivity, surface-enhanced Raman scattering, chemical stability, catalytic activity and antimicrobial activity [6, 7]. Silver nanoparticles are increasingly being applied in biomedicines for their respective broad antimicrobial behavior becoming more attractive for use in drug delivery and targeting especially for their tunable hydrophilic - hydrophobic balance and target specific localization surface features as versatile opportunities in drug delivery and modification systems [6, 7]. The above mentioned properties have enabled silver nanoparticles to serve as a material in the development of new generation electronic, optical and sensor devices.

In the synthesis of nano materials, particularly metallic nanoparticles, has raised greatest attention over the past decade due to their exclusiveproperty that make them suitable in various fields of science and technology. There is a scarcity of effective methods to synthesis a homogeneous size and shape nanoparticles with limited or no toxicity to the human health and the environment. There are two methods for the synthesis of metallic nanoparticles- top-down and bottom-up approaches [8]. In bottom-up approach, reduction of materials components with further self-assembly process which leads to the formation of nanostructures. Representative examples include Quantum dot and formation of nanoparticles from colloidal dispersion. In Top down approach [9] includes the macroscopic structures which can be externally controlled in the processing of nanostructures, such as ball

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proved to be eco-friendly [18]. Silver nanoparticles are the most prototypical target of green methods [19–23] and can be synthesized using plant extracts.Gold and silver metal nanoparticles weregreen synthesized using the Root Extract of Coleous forskohlii as capping and reducing agent for biomedical applications [24].
