Degradation Behavior Of Magnesium-Based Stent And Its Interaction With Vascular/Cell By Microfluidic Chip

In recent years, the excellent experience is the tend of medical treatment, and there is a tend of developing good biocompatible medical implants. Biodegradable implantation has become a research focus for the development of medical surgery Magnesium has good mechanical properties and has no toxicity, good biocompatibility, even can induce tissue growth and been regarded to be a revolutionary biomedical metallic materials,which make it a promising prospective for biodegradable metal stent(BMS).The fast degradation rate of magnesium alloy lead to the degradation products accumulation and the adverse effects associated with vascular tissue/cell,which is the biggest obstacle to the application of biodegradable magnesium alloy stent, Surface modification is applied to control the degradation rate of the magnesium alloy stent and to improve its biocompatibility. The universal evaluation method for testing magnesium alloy properties are used in the static immersion circumstance and are not effective to reflect the degradation process of vascular implant materials in real time. In addition, the interaction between magnesium alloy vascular stents and vascular cell/tissue cannot been evaluated. In this paper, the corrosion resistance coating of magnesium alloy vascular stent is selected as the surface of the Polytrimethylene Carbonate (PTMC) polymer. The atorvastatin calcium (ATVC) was loaded on the PTMC coating, which was used to delay the corrosion rate of the magnesium alloy and to improve the biocompatibility of the magnesium alloy. In addition, Microfluidic chip platform was established and was used to check dynamic degradation process of magnesium alloy and the interaction with vascular endothelial cells at the same time. In the end, we evaluated and validated the interaction of above drug loading coating on blood vessel cells with SD rats abdominal aorta Implants.Our study found:The corrosion of AZ31 wire immersed corrosion was uniform corrosion and the corrosion products were mainly composed of calcium phosphate salt, the proportion of Mg2+、Ca2+ of corrosion products increased with the soaking time; The electrochemical corrosion resistance of AZ-PTMC and AZ-P-ATVC. was significantly improved after AZ31 surface modification by PTMC, and the coating corrosion resistance (Rp) was 67.7 Kohm/cm2,49.9 Kohm/cm2, the corrosion protection efficiency was 89.88% and 98.89% respectively. Rct values were increased by 47.69 and 21.64 times, respectively; Detection of degradation of magnesium alloy stent with microfluidic chip:the main influencing factor of the degradation of magnesium alloy in simulated blood flow environment is the velocity of the fluid., The degradation rate of magnesium alloy increases with the increase of the velocity of the fluid.AZ31 modified by PTMC (loaded ATVC) has good compatibility with HUVECs, and the amount of NO released by the endothelial cells was higher than that of the unmodified magnesium alloy; it was more resistant to corrosion in the initial stage and promoted the vascular endothelial cell adhesion and growth after the implantation. After 3 weeks, the intact endothelial cell layer was distributed in the sample envelope with blood interface, and the smooth muscle cells are arranged in a cyclic order between the sample surface and the endothelial layer, and for AZ-P-ATVC, the inflammation reaction in the capsule and the vessel wall was lower than AZ31 and t AZ-PTMC sample.In our research Microfluidic chip experimental platform was successfully established and was, an effective method for study on interaction between dynamic degradation of biodegradable magnesium alloy stent in vitro and vascular cells. PTMC and ATVC coating was a kind of effective surface modification method to improve magnesium alloy anti-corrosive behavior and biocompatibility.