Antibiofilm efficacy of biosynthesized silver nanoparticles against ampicillin-resistant Staphylococcus aureus: Inhibition on AgNP-coated urinary catheters

Bryophyllum pinnatum , a renowned medicinal plant used for treating a range of ailments such as gastritis, ulcers, burns and various microbial infections. In this study, silver nanoparticles (AgNPs) were biologically synthesized using B. pinnatum leaf extract, where phytochemicals acted as natural reducing and stabilizing agents. The synthesized AgNPs were characterized using UV–vis spectroscopy, TEM, EDS, XRD, FTIR, and dynamic light scattering. Results showed a characteristic UV–vis absorption peak at 420 nm, spherical morphology with an average size of 17 ± 3 nm, strong silver signals in EDS, crystalline structure in XRD, low polydispersity index (0.037), a zeta potential of −13.86 mV, and a hydrodynamic diameter of 58.09 nm. FTIR analysis indicated C–OH, C–O, and C–N functional groups, suggesting capping and stabilization of AgNPs by phytochemicals. LC–MS profiling of B. pinnatum extract revealed a complex composition rich in kaempferol, luteolin, p-coumaric acid, and 4-hydroxycinnamic acid, compounds previously reported for antimicrobial and antibiofilm activities. The AgNPs exhibited potent antibacterial activity against ampicillin-resistant Staphylococcus aureus (ARSA) with a minimum inhibitory concentration of 12.5 µg.mL −1 . Biofilm assays demonstrated dose-dependent inhibition (20–80 µg.mL −1 ), reducing biomass, density, and viable cell counts. FESEM confirmed accumulation of AgNPs on bacterial surfaces and evidence of cell disruption, while cytotoxicity assays on 3T3L1 mouse fibroblasts showed over 80% cell viability at μg.mL −1 , indicating biocompatibility. AgNP-coated silicon catheters (40–80 µg.mL −1 ) significantly reduced bacterial adhesion and ARSA biofilm formation compared to uncoated controls (p < 0.001), highlighting the potential of these surface-modified catheters as an effective anti-biofilm and anti-adhesion strategy. This study demonstrates that B. pinnatum -derived AgNPs are promising candidates for combating resistant bacterial infections and preventing catheter-associated biofilms.