Generating Cell Surface Nucleated Hydrogels with an Artificial Membrane‐Binding Transglutaminase

Abstract Advanced cell therapies require robust matrices for enhanced efficacy and delivery, but fabricating cell‐specific hydrogels with strong tissue adhesiveness remains challenging. Cell membrane engineering offers a non‐genetic strategy to modify cell surfaces and improve therapeutic properties. This study reports an artificial membrane‐binding protein (AMBP), [cat.mTG(S)], that drives in situ formation of proteinaceous hydrogels on the plasma membrane of human dermal fibroblasts (HDFs). The AMBP is created by chemically supercharging (cationizing) microbial transglutaminase (mTG) and then electrostatically complexing it with an anionic polymer‐surfactant (S). Biophysical studies confirm that this polymer surfactant complexation stabilizes the enzyme's structure and partially restores its activity lost during cationization. [cat.mTG(S)] effectively labels HDF plasma membranes with low cytotoxicity, unlike unmodified mTG (no binding) or cationized mTG (internalized). Live‐cell confocal microscopy demonstrates that [cat.mTG(S)] on HDFs successfully cross‐links external proteins into robust hydrogels extending beyond the cell surface and bridging cells, maintaining high cell viability. This AMBP provides a novel, non‐genetic approach for localized, cell‐surface engineering, enabling direct creation of protective and interactive hydrogel microenvironments for advanced cell‐based therapies.