Analysis of drug coated polymer stents studied by XPS

Cardiovascular interventional therapy with stents has emerged as the most effective method for coronary heart disease. However, thrombosis and hyperplasia are the usual pathological responses to the implantation of foreign devices. To suppress this immune response and that of overgrowth and subsequent restenosis anti-inflammatory drugs are now loaded onto the surface of stent implants. Here we investigate the surface of drug loaded polymer stents. The stents are made of polylactic acid (PLA) dosed with an anti-inflammatory drug with a molecular structure of C51HxNO13. XPS yields quantitative information regarding drug distribution and using Argon cluster sputtering we can see the distribution of the drug into the stent structure. Analysis is also performed on stents submerged in buffer solution (PBS) to see the effects on ageing and the propensity for the drug to migrate into the solution with time.