Calcification of solvent-extracted glass and mylar-cast biomer films

Abstract

The polyetherurethane Biomer is cast on glass and Mylar, and is subjected to four different extraction solvents: water, 1% (w/w) Triton X-100, ethanol, and acetone. Soxhlet acetone-extracted Biomer is also cast. The extracted Biomer films are then exposed to a supersaturated calcium phosphate solution at 37°C and pH 7 for 24 h to evaluate their tendency for calcification. Highest amounts of calcium are observed on the Triton X-100-treated samples. Water-, ethanol-, and acetone-exposed films each show decreasing amounts of calcium phosphate. Polymer films cast from Soxhlet-extracted Biomer show the highest resistance to calcification. Higher than expected Ca P ratios for the Triton X-100-treated films and the glass-cast/water-extracted films suggest that contaminants on the surface may attract calcium ions. ESCA analyses of the film surface are made and differences between the glass- and Mylar-cast films extracted by water are found, possibly due to impurities. Both acetone-extracted and Soxhlet-extracted Biomers appear to produce films of a more homogeneous nature with the soft/hard segment ratios similar on each surface. The extraction process also results in changes in the surface topography of the films. Ethanol- and acetone-exposed films each show a roughening of the surface by production of surface bubbles or mounds. The roughening process may be the result of gel-like particles residing in the bulk polymer.