Green Nanotechnology: Sustainable Synthesis of Nanoparticles

Abstract

Nanoparticles (particles smaller than 100nm in atleast one dimension) are characterized by their increased surface-to-volume ratio and high surface-reactivity, which differentiate them from the same material in bulk. These unique characteristics attributed to nanomaterials rationalize their potential for commercial applications like catalysis, imaging, biosensing, other medical and environmental accomplishments. This has led to the development of engineered nanomaterials, including metal-based, polymeric-, and carbon-based nanoparticles. Nanoparticle synthesis by physico-chemical methods employ harsh conditions and produce abundant wastes which jeopardize the environment. Hence, the situation warrants a sustainable and cost-effective green route to nanoparticle synthesis. Novel procedures utilizing plants and microorganisms are gaining interest as they resort to ambient conditions for synthesis in an environment-friendly manner. These processes involve bioreduction of materials, enzymatically or chemically by means of phenols or polysaccharides. The abundance and easy availability of plant resources have attracted research utilizing plant products. The ability of plant extracts to serve as both reducing and stabilizing agents in the nanoparticle synthesis process makes them an ideal biological alternative. As a part of our research on green synthesis of nanoparticles for agricultural applications, a brief study on the effect of such nanoparticles on crop plants was taken up. Iron (Fe) nanoparticles, produced by a plant extract-mediated process, were foliar sprayed to wheat plants under pot culture. The other treatments included foliar spraying with same concentrations of bulk Fe and commercially available Fe nanoparticles. Control pots were foliar sprayed with water. Wheat plants treated with the bio-synthesized Fe nanoparticles had higher biomass which was 13% and 22.5% more than the plants that received foliar sprays of commercial Fe nanoparticles and bulk Fe, respectively. Also, no adverse effects of nanoparticles on plants were visible. Further studies are, but, required for the successful application of nanonutrients to supplement chemical fertilizers and boost agricultural productivity.