Adsorption of alpha-1-microglobulin from biological fluids onto polymer surfaces

A recent study in our laboratory has identified the potential role of urine-derived alpha-1-microglobulin (alpha-1-m) in mediating Pseudomonas aeruginosa adhesion to polystyrene, while other workers have suggested a possible role of the protein in the immunological response. Due to the ubiquitous presence of alpha-1-m in body fluids, the adsorption of the protein from serum, cerebrospinal fluid, urine and used continuous ambulatory peritoneal dialysis fluid onto polystyrene was investigated. The treated surfaces were sequentially immersed in water and increasingly concentrated isopropanol-water solutions in order to selectively desorb bound proteins on the basis of their binding strength. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of the wash supernatants showed different protein desorption profiles for each biological fluid, despite the qualitative similarity between the protein composition of the fluids, and highlighted the uptake of alpha-1-m from each fluid to the surface. In the case of urine, the analysis was extended to commercial polyurethane and silicone stents. The ease of desorption of urine-derived alpha-1-m could be correlated with surface hydrophobicity of the stent biomaterial.