Nanoparticle-antibiotic synergy against bacterial biofilms: mechanisms, therapeutic potential, and future directions
Abstract
Bacterial biofilms pose significant challenges in clinical and industrial settings because of their resistance up to 1000-fold higher than that of planktonic bacteria. This resistance arises from extracellular polymeric matrix, reduced metabolic activity, and horizontal gene transfer. The growing burden of biofilm-associated infections, combined with a deteriorating antibiotic pipeline, necessitates innovative therapies beyond conventional monotherapy. Nanoparticles offer a compelling solution through synergistic combinations with antibiotics. This review critically evaluates studies from 2007 to 2025 on the mechanistic bases of nanoparticle-antibiotic synergy, the quantitative performance metrics, stability and scalability challenges, and strategies to overcome them. It highlights a gap in the literature: no unified performance- metric-centered analysis of progress from in vitro evidence toward clinical translation, and of how nanoparticle stability affects outcomes. Metallic nanoparticles, including silver, gold, zinc oxide, and copper oxide, and non-metallic variants, such as chitosan and carbon-based nanomaterials, exhibit enhanced antibiofilm efficacy in combination with antibiotics. Synergistic mechanisms include improved antibiotic penetration through disruption of extracellular polymeric substances, reactive oxygen species generation, quorum-sensing intervention, targeted nanocarrier delivery, efflux pump inhibition, and disruption of biofilm architecture. Combinations such as silver nanoparticles with β-lactams, zinc oxide nanoparticles with fluoroquinolones, and chitosan nanoparticles with aminoglycosides reduce minimum inhibitory concentrations and minimum biofilm eradication concentrations compared to monotherapies. These synergistic effects increase bacterial susceptibility while lowering dosage. Future research must address toxicity, formulation stability, and manufacturing scalability for safer nanomaterial-based antibacterial treatments, which are relevant to clinicians, pharmaceutical scientists, regulatory agencies, and researchers working in infectious disease management.