Nanoparticle Characterization and Bioremediation: Prospects for Ecological Advantages

Introduction

Nanoparticles are increasingly used in various ðelds, including medical, food, health care, consumer, and industrial purposes, due to their unique physical and chemical properties. These include optical, electrical, and thermal, high electrical conductivity, and biological properties. Due to their peculiar properties, they have been used for several applications, including as antibacterial agents, in industrial, household, and healthcare-related products, in consumer products, medical device coatings, optical sensors, and cosmetics, in the pharmaceutical industry, the food industry and in diagnostics. This enables them to be an object of intensive studies due to their academic interest and the prospective technological applications in various fields (Faivre et al., 2016). Such nanostructures may be synthesized by a wide number of methods, which involve mechanical, chemical and other pathways. So here in this chapter we describe extensively the use of different methods for the characterization of NPs. Research sometimes favours the synthesis of inorganic nanoparticle (NPs) by biological systems makes more biocompatible and environmentally benign. Microorganisms, plant extracts could be an alternative to chemical and physical synthesis of NPs. In physical synthesised silver nanoparticles by laser ablation method the properties of particles synthesised depends upon the wavelength and duration of the laser, the ablation time duration and the effective liquid medium which may or may not contain the surfactant. The chemical synthesis involves the use of hazardous chemicals such as reductants, stabilizers and organic solvents and special requirements for the techniques like high energy radiation, microwave irradiation and inert gas condensation are important (Mittal et al., 2014). The physical and chemical processes often involve high temperatures/pressure for the reaction and the use of hazardous chemicals due to which the biological methods of synthesising metal nanoparticles is gaining importance. Now a day, green nanoparticles synthesis from plant extracts can be used to reduce metal ions to nanoparticles in a single step.This green approach is non-toxic and environment friendly as compared to physical and chemical methods. Silver nanoparticles have several effective application in spectrally selective coating for solar energy absorption, interchelation material for electrical batteries, optical receptors, catalysis for biolabelling, antimicrobial agents etc.Nanoparticles (1-100 nm) exhibits new or improved properties which is based on specific characteristics like size, distribution and morphology (Malabadi et al., 2012).Considering the drawbacks of physio-chemical methods,cost-effective and energy efficient new alternative for AgNP synthesis using microorganisms (Sharma et al., 2009) plant extracts (Song et al., 2009) and natural polymers (Huang et al., 2004) as reducing and capping agents are emerging very fast. The association of nanotechnology and green chemistry unfold the biologically and cytologically compatible metallic nanoparticles which is a strong benevolent from lab to land approach. The biological reduction of silver ions into silver nanoparticles have been reported in Capparis decidua(Ahlawat et al., 2015, 2017). The use of plant and plant extract in nanoparticle synthesis is considered advantageous over microbial based system because it reduces the elaborate process of maintaining cell cultures.The particle size, growth can also be controlled by altering synthesis conditions like pH, reductant concentration, temperature, mixing ratio of the reactants etc. The plant-based synthesis can be carried out either extracellularly or intracellularly. Intracellular synthesis takes place inside the plant whereas the extracellular synthesis occurs in vitro. The findings reported that extracellular synthesis using plant extracts has been considered better as compared to intracellular because it abolishes the extraction and purification methods. Green synthesis of nanoparticles have been reported in Corynebacterium species (Gowramma et al. 2015). The photochemical which are responsible for reduction may be terpenoids, flavonoids, ketones, aldehydes, amides, and carboxylic acids. The water-soluble metabolites such as flavones, organic acids, and quinones are solely responsible for the bioreduction ions. The biological activity of AgNPs depends on factors including surface chemistry, size, size distribution, shape, particle morphology, particle composition, coating/capping, agglomeration, and dissolution rate, particle reactivity in solution, efðciency of ion release, and cell type, and the type of reducing agents used for the synthesis of AgNPs are a crucial factor for the determination of cytotoxicity (Murdock et al., 2008). To evaluate the physically, chemically and biosynthesized nanomaterials, many analytical techniques have been used. In this chapter we elaborate the physicochemical and structural characterization of nanoparticles.