ABSTRACT
Biosynthesis of nanoparticles (NPs) using micro-organisms has emerged as a rapidly developing research area in nanotechnology with various biological entities constantly being used in NPs synthesis, forming an impute alternative to conventional chemical and physical methods. Micro-organisms such as bacteria, cyanobacteria, actinomycetes, yeast and fungi are known to produce inorganic nanoparticles such as gold, silver, silicon, iron, gypsum, titanium, zinc, manganese, lead etc. Metal capture, enzymatic reduction and capping are all steps in the formation of nanoparticles by microbes where metal ions are trapped on the surface or inside microbial cells before being reduced to nanoparticles in the presence of enzymes. Likewise with bacteria, the fungi are used to synthesize nanoparticles after being cultured on agar and then transferred to a liquid medium. The electrostatic binding of metallic ions to the negatively charged carboxylate groups in the enzyme present on the cell wall of mycelia causes intracellular synthesis. Nanoparticles’ most commonly reported modes of action are antimicrobial activity, ROS-induced cytotoxicity, genotoxicity, plant growth promotion, environmental remediation and so on. The controlled synthesis of nanoparticles via beneficial micro-organisms has been successfully validated which is to be directed by their size, shape, dose and concentration dependant.
