Synthesis, Characterization, and Application of Biogenic …
53
2 Approaches for the Synthesis of Nanoparticles
Nanoparticles (NPs) are a group of substances where at least one dimension is lesser
than the 100 nm. A nanoparticle shows various properties, such as enhanced reactivity, sensitivity, surface area, and stability. Nanoparticles are mainly divided into two
parts: organic and inorganic nanoparticles. Natural or organic nanoparticles include
carbon nanoparticles such as fullerenes, and inorganic nanoparticles include magnetic nanoparticles, steel nanoparticles (like silver and gold), and semiconductor
nanoparticles (like titanium dioxide, magnesium, and zinc oxide). Various methods
are used to increase the properties of nanoparticles and reduce the production costs.
The processing conditions of nanoparticles are needed to be controlled for identical shape, identical size, and identical chemical composition of the particles (Ali
Mansoori et al. 2008).
According to Siegel, nanomaterials are differentiated by 0-dimensional, 1dimensional, 2-dimensional, and 3-dimensional (Lusvardi et al. 2017). The nanomaterials exist in different forms, such as single, fused, and aggregated with spherical, tubular, and irregular shapes. Nanoparticles are synthesized by two approaches:
top-down and bottom-up (Mom et al. 2007).
The top-down approach includes the breaking of larger materials into smaller
nanoparticles. It refers to slicing and breaking of large material to get nano-sized
particles. And the bottom-up approach or constructive method refers to building up
of the material from the bottom: atom by atom, molecule by molecule, which means a
build-up of material from atom to clusters to nanoparticles (Chen et al. 2014; Marchiol
2012; Shukla et al. 2017). Top-down approach is mainly used in microfabrication
methods. Attrition and milling for making nanoparticles are examples of top-down
processes. The bottom-up approach is mainly used in the concept of molecular selfassembly. Synthesis of biogenic nanoparticles with the help of microorganism and
plants by bottom-up approach is a very prominent, easy, and cost-effective method
to synthesize green nanoparticles. The synthesis of nanoparticles by top-down and
bottom-up approaches is shown in Fig. 1.
2.1 Synthesis of Nanoparticles
Various conventional techniques and several methods are used for manufacturing of
nanoparticles (NPs). A couple of processes like physical, chemical, and biological
are used for the synthesis of nanoparticle. Physical methods include plasma arcing,
ball milling, thermal evaporate, pyrolysis, laser deposition, and so on. The chemical
methods include colloids, colloids solution, and sol–gel method for nanoparticles
synthesis. But these methods are costly and affect human health by causing certain
environmental risks on the atmosphere and the survival of all organisms. The nontoxic and eco-friendly methods for manufacturing of nanoparticles are biological
methods. The biogenic synthesis of nanoparticles with exact dimension and shapes
53
2 Approaches for the Synthesis of Nanoparticles
Nanoparticles (NPs) are a group of substances where at least one dimension is lesser
than the 100 nm. A nanoparticle shows various properties, such as enhanced reactivity, sensitivity, surface area, and stability. Nanoparticles are mainly divided into two
parts: organic and inorganic nanoparticles. Natural or organic nanoparticles include
carbon nanoparticles such as fullerenes, and inorganic nanoparticles include magnetic nanoparticles, steel nanoparticles (like silver and gold), and semiconductor
nanoparticles (like titanium dioxide, magnesium, and zinc oxide). Various methods
are used to increase the properties of nanoparticles and reduce the production costs.
The processing conditions of nanoparticles are needed to be controlled for identical shape, identical size, and identical chemical composition of the particles (Ali
Mansoori et al. 2008).
According to Siegel, nanomaterials are differentiated by 0-dimensional, 1dimensional, 2-dimensional, and 3-dimensional (Lusvardi et al. 2017). The nanomaterials exist in different forms, such as single, fused, and aggregated with spherical, tubular, and irregular shapes. Nanoparticles are synthesized by two approaches:
top-down and bottom-up (Mom et al. 2007).
The top-down approach includes the breaking of larger materials into smaller
nanoparticles. It refers to slicing and breaking of large material to get nano-sized
particles. And the bottom-up approach or constructive method refers to building up
of the material from the bottom: atom by atom, molecule by molecule, which means a
build-up of material from atom to clusters to nanoparticles (Chen et al. 2014; Marchiol
2012; Shukla et al. 2017). Top-down approach is mainly used in microfabrication
methods. Attrition and milling for making nanoparticles are examples of top-down
processes. The bottom-up approach is mainly used in the concept of molecular selfassembly. Synthesis of biogenic nanoparticles with the help of microorganism and
plants by bottom-up approach is a very prominent, easy, and cost-effective method
to synthesize green nanoparticles. The synthesis of nanoparticles by top-down and
bottom-up approaches is shown in Fig. 1.
2.1 Synthesis of Nanoparticles
Various conventional techniques and several methods are used for manufacturing of
nanoparticles (NPs). A couple of processes like physical, chemical, and biological
are used for the synthesis of nanoparticle. Physical methods include plasma arcing,
ball milling, thermal evaporate, pyrolysis, laser deposition, and so on. The chemical
methods include colloids, colloids solution, and sol–gel method for nanoparticles
synthesis. But these methods are costly and affect human health by causing certain
environmental risks on the atmosphere and the survival of all organisms. The nontoxic and eco-friendly methods for manufacturing of nanoparticles are biological
methods. The biogenic synthesis of nanoparticles with exact dimension and shapes