Metal/metal oxide nanoparticles: A revolution in the biosynthesis and medical applications

Nanoparticles with their various physical and chemical properties are commonly applied in the environmental remediation systems, as well as in the field of biomedicine. We report the recent advances in the biosynthesized metallic nanoparticles (NPs) via eco-friendly, sustainable, and low-cost methods, as well as their use in medicinal strategies. Traditional NPs synthesis approaches are often expensive, harmful to the environment, and do not use clean materials and green energy, which are not good for the environment. On the other hand, in the scientific and technological fields, there is a growing demand/need for the multifunctional and industrially useful NPs, which have aroused interest in the scientific development of simple, eco-friendly, and low-cost strategies that use the alternative, sustainable, and renewable sources. Thus, constituting different scientific and technological advances on the frontier of nanoscience and nanotechnology. In this context, the use of residues from the biomasses as alternative sources for the NPs synthesis appears to be an excellent environmental strategy, which contains secondary metabolites that assist in the process of reduction and oxidation of metallic species for the production of NPs with different morphologies and sizes. In this unusual review, we report the strategic use of nanoparticles obtained via plant and microbial synthesis, as well as their toxic effects on humans, aiming to make a direct relationship with the applications of NPs in the biomedical area.