Plant Extracts Promoted Preparation of Silver and Gold Nanoparticles: A Systematic Review

Eco-friendly synthesis of metal nanoparticles has accrued utmost interest by researchers in the last decade for their distinct properties making them applicable in different fields of science and technology. With regard to its low cost, low environmental effect, zero contamination and higher reducing potential, their synthesis by green chemistry procedure is an emerging area in nanobiotechnology. Plant-based nanoparticles produced are more stable, with high rate of synthesis and are suitable for large scale biosynthesis as compared to the use of microorganisms which require stringent control on cell cultures. Plant-based nanoparticles have advantages over other methods due to presence of biomolecules acting both as capping and reducing agents by increasing the rate of reduction and stabilization of nanoparticles. Furthermore, secondary metabolites present in plants are used for reducing metal ions in single step reaction. In this review paper, we have cited 265 research articles and have outlined 106 plant extract assisted gold and silver nanoparticles. The present review highlights the achievements of metal nanoparticle synthesis, especially silver and gold nanoparticles from plant extracts, along with factors liable for the synthesis of metal nanoparticles. It also focuses on the dye degrading properties and various biological activities of metal nanoparticles, their antimicrobial mechanism of action and the physicochemical properties that influence the biological effects of metallic nanoparticles. Biological activities of metal nanoparticles were also described, including the effect of physicochemical properties of metal nanoparticles on biological activities.