Development of κ‐Carrageenan/Gelatin <scp>pH</scp>‐Responsive Hydrogels for Potential Skin Regeneration Application

Advanced skin care involves innovative, multifunctional, and bio-inspired biomaterials capable of regenerating skin tissue. Here, we report the facile route for the fabrication of the bio-sourced pH-responsive hydrogels based on κ-carrageenan and gelatin, with properties desirable for the treatment of versatile skin disorders. The extensive characterization revealed differences in physicochemical properties due to chemical modifications of the hydrogels. Porosity ranged from 21.67% to 95.81%. By modifying κ-carrageenan hydrogels with gelatin, the Young's modulus values increased proportionally with the gelatin content, ranging from 0.23 to 2.90 MPa, while native κ-carrageenan hydrogels had the lowest values (0.12-0.42 MPa) and native gelatin hydrogels had the highest (10.85-18.03 MPa). Native κ-carrageenan hydrogels exhibited the most pronounced swelling (18.6-27.0), followed by gelatin-modified κ-carrageenan hydrogels (6.5-23.0) and native gelatin hydrogels (7.8-9.0). The native κ-carrageenan hydrogels also displayed the highest water vapor transmission rate (WVTR) (259.99 ± 16-279.91 ± 19 g m^-2 day^-1), while the presence of gelatin lowered it. The hydrogels were preliminary exposed to human fibroblasts (MRC-5 cell line) and then to Caenorhabditis elegans to reveal the effects on whole living organisms. The summarized results suggest that the hydrogels represent advantageous and versatile biocompatible biomaterials set for further investigation as delivery platforms for bioactive molecules suitable for skin tissue regeneration.