Plasma polymerized n-butyl methacrylate coating with potential for re-endothelialization of intravascular stent devices.

Rapid re-endothelialization at an atherosclerotic lesion after stent employment is essential for reducing or preventing local thrombus formation and restenosis. To prevent these complications via enhanced rapid re-endothelialization, poly n-butyl methacrylate (PPBMA) coating was deposited on the stent surface through a radio-frequency plasma polymerization process, with oxygen as the carrier gas. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) characterization confirmed the occurrence of the plasma polymerization and the chemistry properties of the PPBMA. Scanning electron microscopy (SEM) revealed a smooth and dense surface. The wettability of the polymeric films measured by the contact angle indicated that the surface was more hydrophilic (2.0 +/- 1 degrees ) than the original surface (24 +/- 1 degrees ) by the introduction of the PPBMA coating, with a slight decrease even after 4 days. The results of the culture of human umbilical cord veins endothelial cells (HUVEC) in vitro showed that compared with the control of 316L stainless steel, the attachment and growth of cells on the PPBMA-coated surface was significantly enhanced, and a confluent endothelial cells layer was formed after a 4-day culture. A platelet adhesion experiment revealed that the blood compatibility of the substrate surface after PPBMA deposition was also obviously improved. The PPBMA coating remained intact on the stent surface after expansion according to the clinic protocol, indicating that the adhesive strength of PPBMA coating was high enough to withstand the external force in the process of stent expansion. This in vitro pilot study prior to in vivo experiments suggested that this plasma PPBMA was promising for coating stent materials for rapid re-endothelialization.