Bacterial Synthesis of Metallic Nanoparticles for Biomedical Applications

Metallic nanoparticles, especially silver and gold, have promising applications in biomedicine due to their unique optical, electronic, and chemical properties. Conventionally, physical and chemical methods have been used to synthesize these nanoparticles; however, bacterial synthesis has recently emerged as an environmentally friendly, cost-effective, and facile alternative. In this review, we summarize recent progress in understanding the mechanisms underlying microbial nanoparticle biosynthesis and highlight key bacterial strains that have been exploited for efficient, controlled nanoparticle fabrication, including Escherichia coli, Bacillus subtilis, and Geobacillus sp. We discuss current genetic and process engineering strategies to improve the quality, yield, and mono-dispersity of bacterially synthesized metallic nanoparticles. Furthermore, we overview promising biomedical uses of these nanoparticles being actively explored, ranging from drug delivery vehicles, bioimaging tracers, diagnostics, and biosensors, to antibacterial agents and materials with accelerated wound healing capacity. Finally, we outline prospects and challenges toward scale-up, regulation, and adoption of green, biosynthesized metallic nanomaterials for various healthcare applications.