Surface modification of keratin films via thiol–maleimide chemistry toward enhanced anticoagulant response

Protein-based biomaterials are widely used in tissue engineering and regenerative medicine; however, many conventional materials suffer from limitations including immunogenicity, low stability, and risks associated with animal-derived sources. In this context, keratin derived from human hair has attracted increasing attention due to its inherent biocompatibility and cysteine-rich structure, which provides reactive thiol (–SH) groups suitable for chemical modification. In the present study, reductively extracted keratin was utilized to preserve thiol functionality, enabling site-selective modification via thiol–maleimide chemistry using an aminoethyl maleimide (AEM) linker. Through this approach, heparin, a clinically established anticoagulant, was immobilized onto keratin films under mild aqueous conditions. The resulting keratin–heparin films exhibited effective suppression of thrombin-induced coagulation, whereas unmodified keratin showed no anticoagulant activity. Furthermore, spectroscopic and colorimetric analyses confirmed successful heparin conjugation and surface presentation, and no measurable heparin release was detected, indicating stable surface immobilization. Overall, these results demonstrate that thiol-specific functionalization provides a selective, stable, and animal-free platform for anticoagulant surface modification, highlighting the potential of keratin-based materials for blood-contacting biomedical applications.