| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2018) | |
| Biomaterial Surfaces & Interfaces | Tuesday Sessions |
| Session BI-TuP |
| Session: | Biomaterial Interfaces Poster Session |
| Presenter: | David Surman, Kratos Analytical Inc. |
| Authors: | D.J. Surman, Kratos Analytical Inc. J. Counsell, Kratos Analytical Ltd., UK |
| Correspondent: | Click to Email |
Cardiovascular interventional therapy with stents has emerged as one of the most effective treatment methods for coronary heart disease, however, thrombosis and hyperplasia are the usual pathological responses to the implantation of foreign devices into the body. Originally stents were made of steel although these have now been superseded by polymer based materials. Recent developments have introduced a new range of stents made from bio-resorbable polymers, however problems such as thrombosis and hyperplasia still remain. To suppress this immune response and that of overgrowth and subsequent restenosis anti-inflammatory drugs are now loaded onto the surface of stent implants.
In this presentation we investigate the surface of drug loaded polymer stents using X-ray photoelectron spectroscopy (XPS) and sputter depth profiling using Arn+ clusters. The stents studied 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 which is shown to be higher on the abluminal (outer) than the luminal (inner) surfaces of the stent. Combining Argon cluster sputtering with XPS enables the distribution of the drug into the stent structure to also characterised.
Conventional methods to study the effects of aging and drug mobility in stents involve immersion in a buffer solution for varying periods of time. Subsequent analysis of the solution with HPLC determines the extent of drug dissolution from the stent. Although this approach is accurate in determining the amount of drug dissolved, it is still unknown how much drug remains and how it is distributed. This is addressed in this study where the drug distribution for stents immersed in PBS buffer solution for 1-3 months was determined by Arn+ cluster depth profiling of the stents themselves. These results were used to determine the effects on simulated ageing and the propensity for the drug to migrate into the solution with time.