Transdermal hydrogel films were fabricated from gellan gum, chitosan, and agar–agar, employing glutaraldehyde as a covalent crosslinker. The obtained formulation exhibited structural stability, pH-sensitive swelling, and high biocompatibility without the participation of metal ions. FTIR spectra showed the emergence of a characteristic imine (C=N) vibration near 1630 cm⁻¹, confirming covalent network formation through Schiff-base reactions. SEM imaging revealed a homogeneous porous architecture (45–120 μm) that enhances moisture absorption and molecular diffusion. The swelling ratio reached 410 ± 12% at pH 9.18 and 275 ± 9% at pH 4.01, evidencing pronounced pH responsiveness. Mechanical strength measured 0.82 ± 0.03 MPa with elongation of 42 ± 2%, ensuring flexibility for skin application. The temperature-controlled release of methylene blue achieved 78 ± 4% at 40 °C after 24 h, consistent with diffusion-limited transport. This gellan–chitosan–agar hydrogel network crosslinked with glutaraldehyde represents a stable, pH-responsive, and biocompatible platform suitable for wound care and transdermal drug delivery.

This study focused on the development and characterization of bioactive polymeric patches based on agar–chitosan and gellan–chitosan matrices, with and without naringin, aiming to identify formulations with optimal physicochemical and biological performance. FTIR spectroscopy, thermogravimetric (TGA), and differential scanning calorimetry (DSC) analyses confirmed effective crosslinking, stable incorporation of the bioactive compound, and high thermal stability of the patches. Antimicrobial testing against Staphylococcus aureus ATCC 33591 demonstrated that naringin-loaded agar–chitosan films, particularly those with lower chitosan and glutaraldehyde content, exhibited significant activity (MIC = 12.5 mg/mL; inhibition zone 27.67 ± 0.58 mm). Biocompatibility studies, including local skin irritation in rabbits and 28-day topical application in mice, showed no adverse effects. Anti-inflammatory evaluation using the λ-carrageenan-induced paw edema model indicated modest activity of naringin under acute conditions. Overall, agar–chitosan films offered tunable properties and reproducible bioactive incorporation, while gellan–chitosan films provided mechanically robust matrices suitable for further optimization. The results highlight the potential of agar–chitosan patches as biocompatible, structurally stable, and antimicrobial platforms for topical and transdermal delivery of bioactive flavonoids.

Polysaccharide-based films are widely studied as topical systems due to their biocompatibility and tunable structural properties. In this study, composite films based on agar–chitosan (A-series) and gellan–chitosan (G-series) were developed with naringin as a bioactive component. The effects of polymer composition and naringin loading on structural organization, swelling behavior, antibacterial activity, and biocompatibility were evaluated. The results show that agar-based systems exhibited significantly higher swelling (~1370%), indicating a more open and highly hydrated structure, whereas gellan-based films formed more compact networks with moderate swelling (~347%). The incorporation of naringin (0.25 g per formulation) led to a pronounced increase in swelling in gellan-based systems (~777%), suggesting reduced network density, while only a slight effect was observed for agar-based films (~1444%). Antimicrobial studies against Staphylococcus aureus confirmed activity in both systems. The gellan-based formulation showed increased antibacterial activity with higher naringin loading (up to 30.0 ± 0.0 mm), whereas agar-based systems demonstrated maximum activity at lower naringin content (27.67 ± 0.58 mm). These findings indicate that antibacterial performance is influenced not only by the amount of bioactive compound but also by matrix structure and release characteristics. In vivo studies of selected A-series samples confirmed good tolerability of the naringin-loaded film (A1N1), with no signs of systemic toxicity or skin irritation, while anti-inflammatory activity under acute conditions was limited. Overall, the developed polysaccharide-based films show potential as topical systems; however, further optimization of polymer composition and formulation parameters is required to achieve a balance between structural stability and biological performance.