Antifouling Biopolymer Networks via Light- or Temperature-Activated and Fluorescently Traceable Crosslinking of Dextran-Azidocoumarin Conjugates

Sustainable, biocompatible antifouling coatings with built-in traceability are in high demand for advanced material applications. Here, we report azidocoumarin-functionalized dextran (Dex-AzC) that allows for nitrene-mediated C-H insertion crosslinking (CHiC), resulting in intrinsically fluorescent dextran hydrogels. While CHiC-based crosslinking is a versatile methodology for deriving synthetic polymer networks, its application in bio-based systems remains largely unexplored. Incorporation of AzC into the dextran backbone enables network formation via light-induced crosslinking, with high-temperature thermal activation serving as a mechanistic proof-of-concept, while both light and thermal activation provide built-in fluorescence for qualitative visualization. Derived Dex550k-AzC hydrogels exhibit tunable mechanical and optical properties with increasing AzC content and pH-responsive swelling, as well as excellent antifouling behavior and no significant cytotoxicity. Thus, this approach provides a simple route to stable dextran-based hydrogels with built-in visualization capability and highlights the potential of CHiC-based crosslinking in bio-based polymer systems.