Physico-chemical properties of stainless steel 316L coated with ginseng-poly (lactic-co-glycolic acid) for stent application

Abstract

Drug eluting stent is a stent coated with an anti-proliferative drug to prevent in-stent restenosis in blood vessels. Although this stent is superior to the bare stent, another post-stenting complication called late thrombosis, occurs as a result of late re-endotheliazation. Therefore, this project was aimed to develop a drug eluting coating with ginseng extract that contained active ingredients of ginsenosides Rg1 and Re, proven to not only inhibit the proliferation of vascular smooth muscle cells but also to promote the growth of vascular endothelial cells. In this project, poly (lactic-co-glycolic) acid (PLGA) matrix was incorporated with ginseng extract at different ratios: 10%, 30% and 50% (w/w). The gelation solvents were then coated on a stainless steel 316L, a substrate, by a dip coating technique. The coatings were characterized by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM) and contact angle analyses while the drug release profile was studied through one month immersion tests and analyzed by a mass spectrometry instrument (Q-TOF LC-MS). The FTIR analyses confirmed that the coatings were composed of ginseng and PLGA. The SEM images showed that a full coverage and even coating was found on the 30% sample. Higher ratio of PLGA caused higher hydrophobicity but not as high as the bare substrate. The immersion study showed that all PLGA concentrations undergoes initial burst release dependent on the concentrations. The release mechanism for the 30% and 50% samples was a combination of diffusion and swelling-controlled of PLGA whereas the release mechanism for the 10% sample was a Fickian diffusion. The optimum coating was found on the 30% sample as it demonstrated acceptable wettability, even coating coverage and controlled release through the PLGA swelling. The ginseng- PLGA coating by a dip coating technique is practicable and it can be used as a drug eluting coating for stent application.