*2.1.2 Chemical preparation method*

The chemical preparation process involves a bottom-up technique and is the most frequently employed method for preparing silver nanoparticles in water or organic solvents as a stable, colloidal dispersion. Various chemical preparation methods are available, such as sol system, chemical preparations: CdS base, CdS/ HgS/CdS composite, sol-gel process, hydrothermal, pyrolysis and chemical vapor deposition (CVD) process [3] (metallic) silver salt to produce nanoparticles. Here, commonly used reductants are borohydride, citrate, ascorbate and elemental hydrogen that reduce (metallic) silver salt to produce nanoparticles. Chemically synthesized nanoparticles are made of Cu, Ag, Au, Gold, etc., although the use of toxic chemicals in the synthesis protocol cannot be avoided. Alternative methods for nanoparticle synthesis are therefore explored in order to minimize the use of chemicals, and several physical methods were developed and implemented for synthesis of nanoparticles to resolve the chemical preparation.

#### *2.1.3 Biological preparation method*

Physical methods are expensive and require strong material, toughness, strength, etc. for nanoparticle synthesis, which may not be suitable for large-scale

**97**

**Table 1.**

and the respective nanoparticle size.

**3. Nanofabrication using plant sample**

*Phytonanofabrication: Methodology and Factors Affecting Biosynthesis of Nanoparticles*

**Sr. no. Plant species Plant part NP size References** *Aloe vera* Leaves 50–350 nm [5] *Argyreia nervosa* Seeds 20–50 nm [6] *Acorus calamus* Rhizome 31.83 [7] *Allium sativum* Sucrose and fructose 4–22 nm, 4 4 ± 1.5 nm [8] *Boerhaavia diffusa* Whole plant 25 nm [9] *Citrus sinensis* Peel 10–35 nm [10] Cocos nucifera Inflorescence 22 nm [11] *Calotropis procera* Plant 19–45 nm [12] Olive extract 1 ml 30 nm [13] *Passiflora foetida* Leaf disc 14 nm [14] *Terminalia chebula* Fruit extract 100 nm [15] *Thevetia peruviana* Latex 10–60 nm [16]

production of nanoparticles. Although chemical methods are used in the mass production of nanoparticles, the key product generated in the synthesis of nanoparticles tends to cause pollution that ultimately poses a risk to life in terrestrial and aquatic life, leading to environmental accumulation. Physical and chemical methods therefore constitute invaluable processes, while the problem can be overcome by using a biological solution that uses living organisms, bacteria, plants, etc., which is sometimes called the green method. These green strategies include plants, microorganisms and enzymes that are considered to be nonhazardous to humans through the use of natural biological agents that are ecofriendly, biodegradable as reducing, capping and stabilizing agents for nanoparticle synthesis. These biological preparations require a living origin, such as insects, parts of plants, microorganism such as *F. oxysporum*, enzymes, amino acid, vitamin polysaccharides, polyphenols, amino acid, tea, coffee, wine, winery waste, banana, red grape, table sugar and glucose are used for capping and stabilizing. Plant components for the manufacture of nanoparticles have significant advantages over other methods such as easy preparation, processing, cost-effective, rapid development, reproducible, stable components, environmentally friendly, avoiding the use of harsh and toxic chemicals and zero contamination of the environment [4]. Nevertheless, plant-based preparation has become common due to its simple, comprehensive availability and extensive range of samples, including plant part extracts and natural products. In addition, plant, leaf core, root, latex, seed and stem contain polyphenols and have been successfully used for metal particle synthesis [4]. Moreover, plant extract, more specific leaf extract, seed extract, stem extract, fruit extract, root extract and flower extract are used for nanoparticle synthesis. **Table 1** displays many studies of plants mediated silver nanoparticles synthesis reports with their reducing biomolecules

*Reports of silver nanoparticle synthesis using plant species, biomolecules, nanoparticle sizes and references [17].*

The biological method that uses plant samples is the easiest and cheapest way to use a bottom-up approach to nanoparticle synthesis. In broad aspect, there are large

*DOI: http://dx.doi.org/10.5772/intechopen.90918*


*Phytonanofabrication: Methodology and Factors Affecting Biosynthesis of Nanoparticles DOI: http://dx.doi.org/10.5772/intechopen.90918*

#### **Table 1.**

*Smart Nanosystems for Biomedicine, Optoelectronics and Catalysis*

**2.1 Types of nanoparticle preparation**

*2.1.1 Physical preparation method*

*2.1.2 Chemical preparation method*

*2.1.3 Biological preparation method*

In nanosynthesis, the reactant A (metallic salts) interacts with the reactant B (capping agent) where the nucleation reaction occurs. The entire phenomenon occurs at a specific temperature, and the nanoparticle synthesis is significantly improved by the stabilizing (agent) to form metallic nanoparticles and by-products. In several cases, the by-product or larger reaction structures may lead to a mass agglomeration, which suggests aggregation by chemical bonding of larger particles. However, the reacting metallic salts and the capping agent form nanoparticles that have been stabilized by a capping agent that directly prevents mass synthesis.

The physical method uses a "top-down" approach in which the bulk material is pulverized into fine particulate matter by means of force applied, such as crushing, impact, disruption, degradation, cutting, cryo-grinding, grinding, processing and homogenization. Physical methods use the milling process in micro-particle fracturing, and few examples involve ball milling, high-energy ball milling (HEBM), grinding, cryo-grinding, refining and homogenization: high process homogenization (HPH) and medium-pressure homogenization (UHPH). These physical productions are versatile methods that manufacture nanoparticles of larger size, diameter and volume, which are still controlled, generate surface defects, contamination, costly and time-consuming. It may also be possible to produce nanoparticles of the same size, but instrument assembly is very expensive and maintenance is too costly. This imperfection in the form of efficient and expensive maintenance culminated in the space travel of biological sources and methods for the nanoparticle manufacturing process [2]. The synthesis of nanoparticles using biological methods includes the synthesis of nanoparticles using living things or matter. There are several other ways to synthesize nanoparticles, such as chemical and biological

The chemical preparation process involves a bottom-up technique and is the most frequently employed method for preparing silver nanoparticles in water or organic solvents as a stable, colloidal dispersion. Various chemical preparation methods are available, such as sol system, chemical preparations: CdS base, CdS/ HgS/CdS composite, sol-gel process, hydrothermal, pyrolysis and chemical vapor deposition (CVD) process [3] (metallic) silver salt to produce nanoparticles. Here, commonly used reductants are borohydride, citrate, ascorbate and elemental hydrogen that reduce (metallic) silver salt to produce nanoparticles. Chemically synthesized nanoparticles are made of Cu, Ag, Au, Gold, etc., although the use of toxic chemicals in the synthesis protocol cannot be avoided. Alternative methods for nanoparticle synthesis are therefore explored in order to minimize the use of chemicals, and several physical methods were developed and implemented for

synthesis of nanoparticles to resolve the chemical preparation.

Physical methods are expensive and require strong material, toughness, strength, etc. for nanoparticle synthesis, which may not be suitable for large-scale

**2. Nanosynthesis**

**96**

methods.

*Reports of silver nanoparticle synthesis using plant species, biomolecules, nanoparticle sizes and references [17].*

production of nanoparticles. Although chemical methods are used in the mass production of nanoparticles, the key product generated in the synthesis of nanoparticles tends to cause pollution that ultimately poses a risk to life in terrestrial and aquatic life, leading to environmental accumulation. Physical and chemical methods therefore constitute invaluable processes, while the problem can be overcome by using a biological solution that uses living organisms, bacteria, plants, etc., which is sometimes called the green method. These green strategies include plants, microorganisms and enzymes that are considered to be nonhazardous to humans through the use of natural biological agents that are ecofriendly, biodegradable as reducing, capping and stabilizing agents for nanoparticle synthesis. These biological preparations require a living origin, such as insects, parts of plants, microorganism such as *F. oxysporum*, enzymes, amino acid, vitamin polysaccharides, polyphenols, amino acid, tea, coffee, wine, winery waste, banana, red grape, table sugar and glucose are used for capping and stabilizing. Plant components for the manufacture of nanoparticles have significant advantages over other methods such as easy preparation, processing, cost-effective, rapid development, reproducible, stable components, environmentally friendly, avoiding the use of harsh and toxic chemicals and zero contamination of the environment [4]. Nevertheless, plant-based preparation has become common due to its simple, comprehensive availability and extensive range of samples, including plant part extracts and natural products. In addition, plant, leaf core, root, latex, seed and stem contain polyphenols and have been successfully used for metal particle synthesis [4]. Moreover, plant extract, more specific leaf extract, seed extract, stem extract, fruit extract, root extract and flower extract are used for nanoparticle synthesis. **Table 1** displays many studies of plants mediated silver nanoparticles synthesis reports with their reducing biomolecules and the respective nanoparticle size.
