A sustainable, tunable hydrogel membrane platform based on chitosan from marine waste for skin tissue engineering

Seafood processing generates large amounts of biopolymer-rich by-products, such as shrimp shells and fish skin, which remain underutilized. Meanwhile, mechanical and interfacial microenvironmental cues play a crucial role in regulating cell behavior for skin tissue engineering. In this study, we developed a series of tunable hydrogel membranes using shrimp-derived chitosan (CS), gelatin from cold water fish skin (CFSG), and (3-glycidyloxypropyl)trimethoxysilane (GPTMS) as a crosslinker, aiming to create a transparent two-dimensional (2D) platform for skin-associated applications. These hydrogel membranes exhibited tunable physicochemical properties, including high optical transmittance (>85%) and Young's modulus values ranging from 0.2 to 3.9 MPa, providing skin-relevant mechanical cues. The incorporation of CFSG enhanced water absorption and cellular attachment, while GPTMS improved structural integrity, mechanical stiffness, and degradation control. Cytotoxicity evaluation showed excellent cytocompatibility, with cell viability exceeding 80% for L929 fibroblasts, human epidermal keratinocytes (HEKs), and primary human dermal fibroblasts (HDFs) across all formulations. The optimal formulation, of 2% CS, 2% GPTMS, and 2% CFSG, with a stiffness of 1.4 ± 0.1 MPa, supported enhanced HEK surface coverage as well as HDF attachment and spreading, long-term growth, and collagen deposition. Overall, this work establishes a transparent, bioactive, and tunable CS-based hydrogel membrane platform that connects composition-dependent physicochemical properties with skin-relevant cellular responses. The platform supports its use as a 2D interface for skin tissue engineering and in vitro skin-related models, while also contributing to the valorization of marine by-products within a circular bioeconomy framework.