Collagen/heparin coating on titanium surface improves the biocompatibility of titanium applied as a blood-contacting biomaterial.

Thrombosis and restenosis are the main causes leading to failure of cardiovascular and other blood-contacting biomedical devices. It is recognized that rapid re-endothelialization is a promising method for preventing these complications. This article deals with improving the endothelial progenitor cell (EPC) compatibility and hemocompatibility of titanium by coating an extracellular matrix-like film with heparin(hep) and collagen(col) by a layer-by-layer (LBL) self-assembly technique. In the work described here, LBL-produced col/hep coating growth is initialized by deposition of a layer of poly-L-lysine on a titanium surface, which is negatively charged after treatment with NaOH, followed by formation of a multilayer film formed by alternating deposition of negatively charged heparin and positively charged collagen using electrostatic interaction. The X-ray photoelectron spectroscopy results and fluorescence staining of collagen show that collagen is predominant on the surface and that collagen interpenetrates the heparin layer. In vitro EPC attachment and proliferation increase greatly on the col/hep coating. Immunofluorescent staining of cytoskeleton actin reveals that cells on the col/hep coating form a compact confluent cell layer after culture for 3 days. After culture for 5 days, cell viability on the col/hep increases persistently and on titanium the cell viability begins to decrease, showing that the coating possesses the ability to maintain cell viability. Platelet adhesion under dynamic conditions in vitro implies that the hemocompatibility of the col/hep coating is superior to that of titanium. The col/hep coating improves the biocompatibility of titanium and has good potential for application in blood-contacting biomaterials.