UC Riverside

Bioresorbable cardiovascular scaffold (BCS) is promising to eliminate the chronic complications caused by the conventional permanent scaffold by being completely absorbed in the body. Magnesium (Mg) as a bioresorbable metal has attracted considerable attention for BCS. However, Mg must be modified to achieve a slower degradation rate and to induce a desired endothelial cell response to prevent neointimal hyperplasia and endothelium abnormality. To address these challenges, the present dissertation developed polymer-based surface modifications, including different polymer coatings and nanopatterned polymer coatings, to enhance the overall performances of Mg. The first part of the dissertation is a comparative investigation of four representative biodegradable plastics as coating materials, including poly(L-lactic acid), two different poly(lactic-co-glycolic acid), and polycaprolactone. No previous literature thoroughly compared their functionality as coating materials for Mg. It was found that all four polymer coatings slowed the degradation of Mg, and PLGA (50:50) coating promoted the adhesion and spreading of human endothelial cells the most. The second part of the research explored the potential of a novel bioresorbable elastomer, poly(glycerol sebacate) (PGS), as an ideal coating material for Mg. The work verified the effectiveness of PGS coating in reducing the degradation rate of Mg and provided the first reference in the existent literature about the in vitro performances of PGS coatings on Mg. The third part of the dissertation pioneered novel nanopatterned polymer coatings on Mg. The nanopatterns are promising to further enhance the functionality of polymer coatings as a nonbiological and nondrug approach. For the first time, the parallel groove nanopatterns have been successfully fabricated on the PLGA (50:50) coatings and PGS coatings respectively. The nanopatterns on PLGA (50:50)-coated Mg presented a highly-effective biofunction to control the elongation of human endothelial cells without using any biological molecule or drug. The effort established an effective method to control endothelial cell activities on bioresorbable Mg. Overall, the entire dissertation provided extensive knowledge regarding polymer coatings and nanopatterned polymer coatings as surface modification methods for Mg towards desired performances for cardiovascular applications.