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

Alireza  Jafari; Mohammad  Naimi Joubani; Marjan  Daeihamed; Mahan Azizzade  Dobakhshari; Samira Rasouli  Koohi

doi:10.18502/jmb.v13i3.19512

Alireza Jafari Urology Research Center, Razi Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran
Mohammad Naimi Joubani Research Center of Health and Environment, School of Health, Guilan University of Medical Sciences
Marjan Daeihamed Department of Pharmaceutics, School of Pharmacy, Guilan University of Medical Sciences, Rasht, Iran
Mahan Azizzade Dobakhshari Urology Research Center, Razi Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
Samira Rasouli Koohi Department of Physics, University of Alberta, Canada

DOI: https://doi.org/10.18502/jmb.v13i3.19512

Keywords: Irritability, Silver nanostructures, Skin sensitization, Urinary infection, Zinc oxide nanostructures

Abstract

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.