Surface Modification of 316L Stainless Steel by Grafting Methoxy Poly（ethylene glycol） to Improve the Biocompatibility

Percutaneous coronary intervention（PCI） has become an important method for the treatment of the pa- tients with coronary heart disease; however, problems, such as vascular endothelial inflammation, late thrombosis, and stent restenosis still exist as a result of poor biocompatibility of the materials. To enhance the biocompatibility, methoxy poly（ethylene glycol）（mPEG） was immobilized on the surface of AISI 316 grade stainless steel（SS）（AISI： American Iron and Steel Institute）. First, silanized mPEG was synthesized by the direct coupling of mPEG with 3-isocyanatopropyltriethoxysilane（IPTS） via urethane bonds, and the silanized mPEG was then grafted on the surface of SS that was hydroxylated with piranha solution. The results obtained from contact angle goniometry, X-ray pho- toelectron spectroscopy（XPS）, and atomic force microscopy（AFM） confirm that the mPEG modified steel contained more C and Si and less Fe and Cr on its surface, exhibiting a morphological change and decrease in the contact angle. The biocompatibility of the mPEG modified SS was evaluated with fibrinogen adsorption, platelet activation and adhesion, and human umbilical vein endothelial celI（HUVEC） adhesion. Fibrinogen adsorption, platelet activation, and adhesion were clearly suppressed on the surface-modified steel. In addition, human umbilical vein endothelial cell（HUVEC） could adhere and proliferate on the surface of the mPEG-modified SS. This study indicates that the modification of 316L SS with mPEG could enhance the biocompatibility and provide a primary experimental founda- tion for the development of next-generation coronary stent materials for clinical application.