XPS Analysis of Acid Etched Poly (2-Hydroxyethyl Methacrylate) Surfaces

Abstract

Poly(2-hydroxyethyl methacrylate) (pHEMA) surfaces etched by H₂SO ₄, chloric acid (HClO₄/KClO₃), and HF, were analyzed by electron spectros copy (XPS) to study the surface chemical changes that led to good attachment and growth of endothelial cells on the sulfuric acid treated surface, but not on the others. Sulfonation did not occur. With all three acid treatments, the domi nant chemical structures on the new surfaces were not free methacrylic acid groups that might have been produced by hydrolysis of the ester groups. Some of the several possible reactions between the acids and the pHEMA surface are not consistent with the XPS analyses. The acid treated surfaces contain mainly hydroxyl, ether and ester groups, and one or several among these enhance cell attachment and growth. Also, our data indicate caution in using XPS data as predictors of biomedical performance.