A Review on the Various Mechanisms of Green Synthesis of Metal Nanoparticles for Biomedical Applications

Abstract: Due to the hazardous effects of chemicals used, Green chemistry replaces the conventional techniques involved in nanotechnology. Green chemistry is a branch of science dealing with microbiology, phytology, and chemical engineering with the development of products by manipulating these three domains. Green synthesis is an interdisciplinary domain that relies on the use of non-toxic, bio-safe reagents, which are eco-friendly and safe to use in bio-nanotechnology and provide environmental benefits as an option other than the conventional physical and chemical methods for developing technology. This article will critically present the various approaches and methods for nanoparticle synthesis using microorganisms like bacteria, fungi, yeasts, archaea, viruses, algae, etc. By optimizing with laboratory conditions, nanoparticles of different ranges of physical characteristics can be synthesized. Nanoparticles with well-defined properties have been reported to be synthesized by green chemistry, for many biomedical applications. Green synthesis of nanoparticles is non-toxic, eco-friendly, and compatible to be used for medical procedures, and the rate of nanoparticle formation and their size could be regulated by various controlling factors like pH, temperature, concentration, time exposure, etc. The use of microbes for nanoparticle synthesis can be broadly divided into intracellular and extracellular based on their being produced from the extracts of microorganisms, which can be employed either as reducing agents or protective agents for the synthesis either extracellular or intracellular in the presence of enzymes generated by cells. This review aims to summarize nanoparticles of Au, P, Ag, Pt, CdS, Pt ZnO, etc as the primary focus. Additionally, a short glimpse often hybrid chemical-biological methods have also been presented.