Surface characteristics and biological properties of paclitaxel-embedding PLGA coatings on TiNi alloy

Surface characteristics and biological properties of paclitaxel-embedding poly(lactide-co-glycoliade) (PLGA) coatings on TiNi alloy have been studied systematically. Surface topography, chemical construction, paclitaxel cumulative release characteristic and interactions between platelets and paclitaxel-embedding PLGA coatings are studied by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), high performance of liquid chromatography (HPLC) and platelet adhesion test. AFM results show that the surface roughness decreases from 350 nm to below 52 nm after completion of PLGA coatings on passivated TiNi alloy samples. XPS results indicate the PLGA coating without paclitaxel has the maximum percentage of CC bond, which is about 61%, and the minimum percentage of C*OCO and OCO bonds comparing with PLGA coatings after adding paclitaxel. HPLC results show that paclitaxel releases fast in vitro from the paclitaxel-embedding PLGA coatings at the beginning, and then the cumulative release amount of the paclitaxel increases slowly with increasing of incubation time. The amount of paclitaxel released is not related to the paclitaxel embedded. It has been found that the amount of platelets adhered on the surface of passivated TiNi alloy sample are greater than that on the surface of the PLGA coated on TiNi alloy. With the increase of paclitaxel, the amount of adhered platelets increases and the shape of platelets were activated obviously. When the content of paclitaxel reaches 30%, the platelets exhibit a phenomenon of significant accumulation.