Green nanotechnology: Harnessing metal and its oxide nanoparticles to overcome microbial resistance

The systematic exploration of novel strategies for treating drug-resistant bacterial infections has become increasingly important amid the continuous emergence of resistant bacterial strains. Owing to their remarkable antibacterial properties and therapeutic effects—significantly influenced by their synthesis processes—metal and metal its nanoparticles have been extensively applied in diverse antibacterial scenarios. However, high costs, excessive by-product generation, and severe environmental harm often restrict current synthesis approaches. Conversely, green synthesis methods have attracted considerable research interest owing to their benefits: cost-effectiveness, high efficiency, environmental friendliness, and relative safety. The primary objective of this review is to offer a comprehensive summary of the synthesis methods for metal and its oxide nanoparticles. To facilitate reader comprehension, key mechanisms are presented in graphical form. This review also discusses the in-situ and ex-situ characterization methods for these nanoparticles, which are critical steps in evaluating their properties. The correlation between nanoparticle structure and antibacterial activity is also emphasized, as this relationship is vital for synthesizing nanoparticles with enhanced antibacterial performance. Finally, we thoroughly discuss the safety, stability, and biocompatibility of metal and its oxide nanoparticles, alongside their antibacterial properties and clinical application potential. The primary aim of this review is to provide valuable insights and recommendations for the efficient and environmentally sustainable synthesis of metal and its oxide nanoparticles.