This study explores the innovative approach in the development of freeze-dried hydrogel films, leveraging the unique properties of gum Karaya (GK), poly-(vinyl alcohol) (PVA), poly-(ethylene glycol) (PEG), and glycerol with a coating of octenidine dihydrochloride (OCT). These innovative hydrogel films exhibit at a certain glycerol concentration a sandwich-like structure, achieved through a tailored freeze-drying process, which enhances transparency and mechanical stability. OCT provides superior antibacterial performance, effectively combating multidrug-resistant bacteria with a controlled and gradual release mechanism, surpassing conventional OCT solutions that require frequent reapplication for infected wound treatment without the creation of bacterial resistance. Advanced environmental scanning electron microscopy (A-ESEM) reveals the complex microstructure of the hydrogel, highlighting the dense surface layer and interconnected porous bulk. Variations in glycerol concentrations proved to significantly impact hydrogels' properties. Increasing the glycerol concentration decreases the pore size (around 4.5 μm) while enhancing the polymer network density and flexibility. However, low concentration increases the pore size (7.8-15.6 μm), impacting enhanced swelling behavior and hydrolytic stability. OCT's rapid antibacterial action, releasing over 30% within the first hour and maintaining prolonged activity for up to 2 weeks, emphasizes the material's potential for diverse applications. Hydrogels' remarkable transparency, porosity, structural stability, and antibacterial efficacy against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli strains suggest promising uses as transparent dressings, biomedical devices, and infection-resistant surfaces.

Central European Institute of Technology Brno University of Technology Purkyňova 656 123 612 00 Brno Czech Republic

Department of Burns Medicine 3rd Faculty of Medicine Charles University and University Hospital Královské Vinohrady Škrobárova 1150 50 100 34 Prague Czech Republic

Department of Microbiology St Anne's University Hospital Brno and Faculty of Medicine Masaryk University Pekařská 53 602 00 Brno Czech Republic

Faculty of Electrical Engineering and Communication Brno University of Technology Technická 10 616 00 Brno Czech Republic

Institute of Scientific Instruments of the Czech Academy of Sciences Královopolská 147 612 00 Brno Czech Republic

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