Selective Photoinduced Antibacterial Activity of Amoxicillin-Coated Gold Nanoparticles: From One-Step Synthesis to in Vivo Cytocompatibility.

Photoinduced antibacterial gold nanoparticles were developed as an alternative for the treatment of antibiotic-resistant bacteria. Thanks to the amoxicillin coating, they possess high in vivo stability, selectivity for the bacteria wall, a good renal clearance, and are completely nontoxic for eukaryotic cells at the bactericidal concentrations. A simple one-step synthesis of amoxi@AuNP is described at mild temperatures using the antibiotic as both reducing and stabilizing agent. Time-resolved fluorescence microscopy proved these novel nano-photosensitizers, with improved selectivity, are bactericidal but showing excellent biocompatibility toward eukaryotic cells at the same dose (1.5 μg/mL) when co-cultures are analyzed. Their stability in biological media, hemocompatibility, and photo-antibacterial effect against sensitive and antibiotic-resistant Staphylococcus aureus were evaluated in vitro, whereas toxicity, renal clearance, and biodistribution were studied in vivo in male Wistar rats. The use of these nanoparticles to treat antibiotic-resistant infections is promising given their high stability and cytocompatibility.