Surface immobilization of heparin and chitosan on titanium to improve hemocompatibility and antibacterial activities

Biomaterial-related thrombus formation and bacterial infections are still the most common causes for the failure of medical devices. We report a facile and a highly efficient strategy to inhibit thrombosis and bacteria attachment, by immobilizing heparin (HA) and chitosan (CS) on titanium (Ti). Alkali-treatment was firstly performed on Ti to form nanoporous network structures containing hydroxyl radical (-OH), followed by immobilizing HA and CS on alkali-treated Ti in turn by layer-by-layer assembly. HA was immobilized on alkali-treated surface by covalent immobilization and CS was immobilized on heparinized surface by electrostatic bonding. The successful immobilization of both HA and CS on Ti was confirmed by analyses of scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and water contact angles. The antithrombotic activities of the immobilized surfaces were demonstrated by a reduction in protein absorption, blood clot mass and platelet adhesion. Additionally, the immobilized surfaces also exhibited excellent antibacterial activities against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The modified surfaces on Ti was established as an effective and promising method to simultaneous improve the hemocompatibility and antibacterial performances of blood contact medical device.