investigation of the antibacterial effects, skin sensitivity, and irritant properties of a lubricating gel containing silver/zinc oxide nanostructure and lidocaine in an animal model

Background: urinary tract infections (utis), predominantly catheter-associated (cautis), cause significant morbidity (~380,000 cases), mortality (~9,000-13,000 deaths), and healthcare costs annually. cautis initiate via bacterial biofilm formation on catheters. current antimicrobial catheters (e.g., silver ions, antibiotics) face limitations like poor efficacy, resistance, and non-adjustability. nanostructure coatings offer promise; notably, combining ag/zno nanostructures leverages enhanced biocompatibility and potent antibacterial effects for novel cauti prevention strategies.methods: agnps were chemically synthesized via silver nitrate reduction (sodium citrate/sodium borohydride); zno-nps were prepared from zinc acetate/sodium hydroxide. a lubricant gel containing 2% lidocaine and ag/zno nanostructures (2:8 v/v ratio) was formulated. nanostructure characterization included dls, tem, and icp-oes. antibacterial efficacy was assessed via disk diffusion and microdilution (mic/mbc) against s. aureus and p. aeruginosa. biocompatibility was evaluated via rabbit ocular irritability and guinea pig maximization test (iso 10993-10).results: dls/tem characterization showed agnps (24.4 nm, spherical) and zno-nps (52.48 nm, clustered) were mono-disperse (pdi ~1 and 0.667). zeta potential confirmed stability (ag: -20.7 mv; zno: -0.709 mv). icp-oes quantified concentrations (ag: 25 ppm; zno: 970 ppm). antibacterial assays revealed weak agnp activity (mic/mbc >12.5 µg/ml for both pathogens) but potent zno-np effects (e.g., s. aureus mic: 0.406 µg/ml). ag/zno hybrids exhibited enhanced efficacy, especially against s. aureus (mic: 0.02/3.12 µg/ml). the gel was non-irritating (rabbit ocular test) and non-sensitizing (guinea pig maximization test).conclusion: the active formulation consisting of mixed silver and zinc oxide nanostructures combined with a medical lubricant containing 4% lidocaine demonstrates effective antibacterial activity against pseudomonas aeruginosa and staphylococcus aureus, while exhibiting no irritant or sensitizing properties in laboratory animals.