Improved endothelialization of NiTi alloy by VEGF functionalized nanocoating.

To improve surface endothelialization of NiTi alloy substrate, a nano-structured coating functionalized with vascular endothelial growth factor (VEGF) was fabricated via polydopamine (PDOP) as intermediate layer. The successful preparation of VEGF conjugated nanocoating was demonstrated by X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), respectively. Inductively coupled plasma mass spectrometry (ICP-MS) test showed that the formed nanocoating significantly reduced the release of Ni ion from NiTi alloy in simulated body fluid. The biological behaviors of endothelial cells adhered to modified NiTi alloy substrates, including cell proliferation, cell spreading and production of nitric oxide and prostacyclin were investigated in vitro. The results suggest that surface functionalization of NiTi alloy substrate with VEGF is beneficial for cell growth. The approach presented here affords an alternative for surface modification of NiTi implants applied as heart and vascular implant devices.