Triple-action biosynthesized silver nanoparticles: Targeting MDR UTI pathogens, oxidative stress, and bladder cancer cells

Background: Multidrug-resistant (MDR) bacteria like Staphylococcus aureus and Pseudomonas aeruginosa are a major cause of urinary tract infections (UTIs), necessitating novel antimicrobial solutions. Biosynthesized silver nanoparticles (AgNPs) present a promising alternative. Objectives: This study aimed to biosynthesize AgNPs using nonpathogenic Escherichia coli and evaluate their antimicrobial, antioxidant, and cytotoxic properties. Methods: AgNPs were biologically synthesized using cell-free supernatants from E. coli and characterized by UV-Vis spectroscopy, XRD, AFM, and TEM. Antibacterial activities against MDR S. aureus and P. aeruginosa were assessed using the MIC/MBC assay. Antioxidant capacity was measured via DPPH scavenging and cytotoxicity was evaluated using MTT assays in HT-1376 and HDFn cell lines. Results: Antimicrobial testing against MDR pathogens demonstrated dose-dependent activity: for S. aureus, MIC and MBC were 31.45 μg/ml and 62.9 μg/ml, respectively; for P. aeruginosa, MIC was 62.91 μg/ml and MBC was 125.8 μg/ml. Antioxidant activity (DPPH assay) increased with AgNP concentration (7.94% at 15.72 μg/ml to 41.30% at 125.82 μg/ml). Cytotoxicity assays showed a significant dose-dependent reduction in bladder cancer HT-1376 cell viability (maximum 73.81% reduction at 400 μg/ml), whereas normal dermal fibroblasts (HDFn) exhibited lower sensitivity (maximum 42.40% reduction at 400 μg/ml). The predominant uropathogens isolated were E. coli (47.14%), S. aureus (21.42%), and P. aeruginosa (18.57%). Conclusion: Biosynthesized AgNPs show significant potential as multifunctional agents, effectively targeting MDR uropathogens and bladder cancer cells with minimal harm to normal cells, highlighting their promise for therapeutic applications.