The misuse of antibiotics has led to a global increase in antimicrobial resistance, necessitating the development of novel antibacterial strategies. Inorganic nanomaterials, with their unique physicochemical properties and multifaceted antimicrobial mechanisms, offer a promising alternative. This review comprehensively discusses recent advances in zinc oxide (ZnO) nanoparticles and their composites within the field of antibacterial technology. Pure ZnO nanoparticles exhibit intrinsic antibacterial activity through the generation of reactive oxygen species (ROS) and the release of zinc ions (Zn2+), with efficacy highly dependent on particle size, morphology, and crystallinity. Strategies such as morphological control (e.g., nanosheets, nanorods), noble metal modification (e.g., Ag, Pt, Pd), metal ion doping (e.g., Co, Nd), and compositing with other metal oxides or carbon-based materials (e.g., GO, rGO) have been shown to significantly enhance antibacterial performance. The antimicrobial mechanisms of ZnO-based nanomaterials are explored in depth, emphasizing the synergistic effects of ROS-induced oxidative stress, Zn2+-mediated membrane disruption and enzyme inactivation, and physical damage. Despite the considerable potential of ZnO composites in combating multidrug-resistant bacteria and biofilms, challenges remain regarding biocompatibility, environmental toxicity, and scalable synthesis. Future research should focus on green synthesis routes, targeted delivery systems, combination therapies, and long-term safety assessments to facilitate clinical and industrial translation.
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