Sericin-Capped Gold Nanoparticles as a Potential Antimicrobial in Human Urine through Disrupting Bacterial Membranes and Changing Metabolism

Catheter-associated urinary tract infection (CAUTI) is a prevalent healthcare-associated infection, necessitating alternative therapeutic strategies. Sericin-conjugated gold nanoparticles (AuNP-Sericin) offer broad antibacterial and biomedical potential, leveraging gold nanoparticles' inertness and low cytotoxicity with sericin's biocompatibility. This study aims to characterize the molecular mechanisms underlying AuNP-Sericin's antibacterial activity in human urine and to suggest its application in urinary catheters. Forty catheter-associated urine samples were collected for urinalysis and subsequently treated with AuNP-sericin for a proteomics-based molecular mechanism study. Additionally, the minimum inhibitory concentration of AuNP-sericin was determined against common uropathogens, including Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, and Proteus mirabilis, as well as against 10 single colonies derived from a urine sample. The scanning electron microscope revealed AuNP-sericin accumulation on microorganism cell surfaces via electrostatic interactions. This situation may disrupt membranes, block nutrient access, and thus interfere with microbial metabolic pathways. Proteomics investigation confirmed that AuNP-sericin can restrict microbial growth by trapping their membranes, interfering with translation and metabolism. In conclusion, AuNP-sericin can limit bacterial growth and biofilm formation, potentially reducing antibiotic consumption and UTI rates, which are major causes of hospitalization.