Nanofiberous coating for Bare Metal Stents: A comparative study of coaxial and monoaxial modes

Abstract

Stents are coated with anti-thrombogenic/antiproliferative agents to improve the effectiveness. The techniques used to apply the drug/polymer solution to the stent are dipping, ultrasonic / electrospray, and electrospun nanofiber coating. Electrospun fibers have shown many outstanding properties such as large surface area, high length/diameter ratio, flexible surface functionality, and superior tensile performance. Nanofibrous coat can be prepared by monoaxial with single needle or coaxial mode using dual spinneret technique to control the drug release in a sustained manner. In this work, a comparative study of the three coating techniques using PLGA (50:50) and docetaxel has been done. The dip coated samples showed a very less porous structure, high mechanical strength and release was biphasic with maximum 80% cumulative release. In case of spray and nanofibrous coated samples, the surface morphology was porous with high surface area and only abluminal side coating. But the mechanical flexibility of spray coated samples was very less compared to the other two samples. The result was further compared for drug release behaviour with two modes of nanofibrous coating, i.e. coaxial and monoaxial. It has been observed that coaxial nanofibers give a sustained drug release with lesser concentration of drug compared to monoaxial mode. The biocompatibility study confirmed the compatibility of all the polymeric form for human blood cells. Therefore, the spray and nanofibrous coating are preferable over dip coating with improved coating and lesser drug wastage in the luminal side. Again, nanofiber drug release property can be modified using monoaxial and coaxial modes of coating as per application.