<b>Comparative Antimicrobial Efficacy of Chitosan–Graphene Oxide and Chitosan–Reduced Graphene Oxide Membranes</b>

Background: Hospital-associated infections and antimicrobial resistance remain major clinical challenges, particularly in settings with high bacterial burden and frequent antibiotic exposure. Chitosan is a biocompatible antimicrobial polymer, but its limited mechanical stability restricts broader biomedical use. Graphene oxide and reduced graphene oxide may improve chitosan membrane performance, although their different oxidation states may produce distinct antimicrobial, mechanical, and biological effects. Objective: To compare the antimicrobial efficacy, mechanical stability, and basic biocompatibility of pure chitosan, chitosan–graphene oxide, and chitosan–reduced graphene oxide membranes. Methods: This comparative experimental study evaluated three membrane groups prepared by solution casting. Physical and mechanical properties were assessed using thickness, water uptake, tensile strength, elongation at break, and surface pH. Antimicrobial activity was tested against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae using agar diffusion and direct-contact viable count methods. Cell viability and hemolysis were used for basic compatibility assessment. Results: Chitosan–GO showed the highest tensile strength (32.7 ± 2.1 MPa), largest inhibition zones, and greatest 24-hour bacterial reduction (94.3 ± 2.8%), followed by chitosan–rGO and pure chitosan. Pure chitosan had the highest cell viability (93.4 ± 2.5%), while chitosan–GO retained acceptable viability (88.7 ± 2.8%) and lower hemolysis than chitosan–rGO. Conclusion: Chitosan–graphene oxide demonstrated the best overall balance of antimicrobial efficacy, mechanical strength, and biological compatibility, supporting its potential for antimicrobial biomaterial development