A Comprehensive Review of Antimicrobial Nanoformulations: Engineered to Combat Biofilm-Associated Infections

Biofilm-associated infections represent a critical challenge in modern medicine, accounting for approximately 80% of all microbial infections and demonstrating up to 1000-fold higher antimicrobial resistance compared to planktonic bacteria. The extraordinary recalcitrance of biofilms stems from a complex interplay of physical barriers (extracellular polymeric substance matrix), chemical gradients (pH and oxygen heterogeneity), and biological defenses (persister cells and horizontal gene transfer), rendering conventional antibiotics largely ineffective. This comprehensive review highlights the transformative potential of antimicrobial nanoformulations in overcoming these formidable barriers through strategic design principles and diverse mechanisms of action. Evidence demonstrates that rationally engineered nanocarriers achieve improvements in bacterial killing, biofilm biomass reduction, and colony-forming unit reductions compared to free antibiotics. Advanced stimuli-responsive systems exploiting biofilm-specific triggers (acidic pH, bacterial enzymes, elevated ATP) and externally applied stimuli (near-infrared photothermal therapy, ultrasound sonodynamic therapy) enable on-demand therapeutic activation with unprecedented precision, achieving >99.999% bacterial elimination and near-complete biofilm eradication. Despite these remarkable advances, clinical translation remains hindered by challenges in scalability, comprehensive safety evaluation, and regulatory pathway navigation. This review establishes a consolidated evidence base for the design of next-generation antimicrobial nanoformulations, highlights their potential to address biofilm-associated infections, and identifies key knowledge gaps and translation barriers that must be addressed to realize their therapeutic promise.