Photo-Curable GelMA-Chitosan Bioadhesive Hydrogel: An Evaluation of Mechanical and Adhesive Properties

Polymer-based adhesives are used in tissue repair; however, their application is frequently limited by suboptimal mechanical or adhesive properties. This study aims to develop a natural polymer-based photo-cross-linkable and structurally robust bioadhesive hydrogel, utilizing gelatin methacryloyl (GelMA) and chitosan. We compared the mechanical properties and adhesiveness of various GelMA-chitosan hydrogel formulations cross-linked by three different photo-initiator systems—[tris (2,2′-bipyridyl) dichlororuthenium (II) hexahydrate ([RuII (bpy)3]2+ and sodium persulfate (Ru/SPS), lithium acylphosphinate (LAP), and 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propanone (Irgacure 2959)]. The Ru/SPS cross-linked GelMA-chitosan hydrogel showed a higher compressive modulus than GelMA hydrogel at both neutral and alkaline pHs, suggesting potential use during infection or delayed wound healing. Chitosan addition to GelMA significantly enhanced hydrogel adhesiveness, with Ru/SPS cross-linked hydrogel exhibiting the highest adhesive strength to cartilage (tensile: ⁓100 kPa) and skin (tensile: ⁓25 kPa, lap shear: ⁓43 kPa). Rheological analysis confirmed the shear-thinning behaviour of the hydrogel precursor solution, indicating its injectability. Moreover, the hydrogel demonstrated robust adhesion to cartilage and skin during ex vivo joint movement and skin bend tests, suggesting its utility in dynamic tissue environments. This study suggests that Ru/SPS cross-linked GelMA-chitosan hydrogel is a promising natural polymer-based bioadhesive, warranting further exploration in a variety of tissue repair applications.