Methacrylation of Fibrillar Sea Urchin Collagen: Production of Sustainable, Stable, and Functional Hydrogels

Marine-derived biomaterials represent a sustainable alternative to mammalian sources for biomedical applications, aligning with circular economy principles. In this study, native fibrillar collagen extracted from food waste of the sea urchin was successfully methacrylated for the first time to produce structurally stable, photo-cross-linkable hydrogels. A dedicated methacrylation protocol was developed to overcome the intrinsic limitations imposed by the supramolecular organization of intact collagen fibrils, enabling effective functionalization while preserving their native architecture. Methacrylated collagen hydrogels were obtained via UV-induced photo-cross-linking and further functionalized with sea urchin-derived polyhydroxynaphthoquinones to generate antioxidant composite hydrogels. The resulting biomaterials were comprehensively characterized in terms of ultrastructure, macroporosity, swelling behavior, mechanical properties, water uptake, degradation kinetics under physiological and enzymatic conditions, antioxidant activity, and in vitro cytocompatibility using human dermal fibroblasts. Compared with non-methacrylated collagen scaffolds, methacrylated hydrogels exhibited enhanced structural stability, reduced swelling-induced deformation, and significantly increased resistance to degradation. Incorporation of sea urchin-derived antioxidants further improved hydrogel stability and conferred marked antioxidant activity, which was largely preserved after incorporation. In vitro assays demonstrated that the hydrogels supported cell viability and metabolic activity. Overall, these findings demonstrate that methacrylated sea urchin collagen hydrogels, with or without antioxidant loading, constitute a promising class of sustainable biomaterials for tissue engineering applications.