Green synthesis of metal nanoparticles using plants

Green synthesis of zinc oxide nanoparticles by aloe barbadensis miller leaf extract: Structure and optical properties

Biosynthesis of silver nanoparticles using citrus sinensis peel extract and its antibacterial activity

Green synthesis of silver nanoparticles using olive leaf extract and its antibacterial activity

Nanotechnology is a new and emerging technology with wealth of applications. It involves the synthesis and application of materials having one of the dimensions in the range of 1-100 nm. A wide variety of physico-chemical approaches are being used these days for the synthesis of nanoparticles (NPs). However, biogenic reduction of metal precursors to produce corresponding NPs is eco-friendly, less expensive, free of chemical contaminants for medical and biological applications where purity of NPs is of major concern. Biogenic reduction is a "Bottom Up" approach similar to chemical reduction where a reducing agent is replaced by extract of a natural products with inherent stabilizing, growth terminating and capping properties. Furthermore, the nature of biological entities in different concentrations in combination with reducing organic agents influence the size and shape of NPs. Present review focuses on microbes or plants based green synthesis of Ag, Au, Cu, Fe, Pd, Ru, PbS, CdS, CuO, CeO2, Fe3O4, TiO2, and ZnO NPs and their potential applications.

Green synthesis of nanoparticles and its potential application.

Development of biologically inspired experimental processes for the synthesis of nanoparticles is evolving into an important branch of nanotechnology. The present study deals with the synthesis of silver nanoparticles using Gliricidia sepium. On challenging, leaf broth of Gliricidia sepium and aqueous AgNO3 (1mM) solution changed from yellowish green to brown, the final color appeared gradually with time. The entire reaction mixture turned to brown color after 12 hrs of reaction, and exhibits an absorbance peak around 440 nm characteristic of Ag nanoparticle, its surface plasmon absorbance and due to different shapes of lone spherical or roughly spheri- cal Ag nanoparticles. Transmission electron microscopy (TEM) analysis showed silver nanoparticles which are polydispersed and ranged in size from 10-50 nm with an average size of 27 nm, the particles were predominantly spherical. X-ray diffraction (XRD) studies reveals a number of Braggs reflections that may be indexed on the basis of the face centered cubic structure of silver nanoparticle and Fourier Transform Infrared Spectroscopy (FTIR) analysis, which showed that silver nanoparticles are capped. Phytosynthesized silver nanoparti- cles show the antibacterial activity against the Staphylococcus aureus ATCC 6538P, Escherichia coli ATCC 8739, Pseudomonas aerugi- nosa ATCC 9027 and Klebsiella pneumoniae (clinical isolate). The approach of phytosynthesis appears to be cost efficient eco-friendly and easy alternative to conventional methods of silver nanoparticles synthesis.

R. Lakkakula

Papers

Phytosynthesis of Silver Nanoparticle Using Gliricidia sepium (Jacq.)