AuNPs-amoxicillin nanocarriers enhance antibacterial activity against methicillin-resistant Staphylococcus aureus: Efficacy and toxicity evaluation.

INTRODUCTION: The increasing prevalence of antibiotic-resistant bacteria, particularly Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA), necessitates the development of more effective antibacterial strategies. Gold nanoparticles (AuNPs) have emerged as promising nanocarriers to improve antibiotic delivery and antibacterial efficacy. METHODS: Amox-AuNPs were synthesized using the Turkevich method and characterized by UV-Vis spectroscopy, FTIR, particle size analysis, zeta potential, FE-SEM, TEM, and stability evaluation. Antibacterial activity was assessed using microdilution and disk diffusion assays. Cytocompatibility and safety were evaluated using the MTT assay on MCF-10A cells and the Fish Embryo Toxicity (FET) test. The selectivity index (SI) was determined from the estimated IC50 and MIC90 values. RESULTS: Characterization confirmed successful conjugation of amoxicillin onto AuNPs with high entrapment efficiency (76.89%) and good colloidal stability over 20 days. Amox-AuNPs exhibited significantly enhanced antibacterial activity against S. aureus and MRSA, with an estimated MIC90 of 2.38 ppm against MRSA. Cytotoxicity testing demonstrated cell viability above 70%, while the estimated SI of 14.78 and FET results indicated favorable biocompatibility and safety. CONCLUSION: Amox-AuNPs effectively enhanced the antibacterial activity of amoxicillin while maintaining good physicochemical stability, favorable biocompatibility, and a wide therapeutic window, highlighting their potential as a nanocarrier for combating antibiotic-resistant bacteria.