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UBC Theses and Dissertations

Adsorption of bovine serum albumin to polyethylene tubing reversibility and pH-dependence Needham, Judy


This thesis is concerned with the adsorption of bovine serum albumin to polyethylene tubing. A method using radioiodinated protein was developed to measure the surface concentration taking into account the dilution effect for miscible displacement in a capillary. A steady-state surface concentration was established within 2 hours. Adsorption did not depend on the ratio of radiolabelled to unlabel led protein. The adsorption isotherm was Langmuir-like with a plateau concentration of approximately 0.2 μg/cm². Two methods were used to calculate the surface concentration in the desorption study. The surface concentration calculated by depletion of the total radioactivity was always higher than that calculated from assaying the radioactivity associated with the tubing. Desorption of at least 5% of the loosely bound protein occurs. The surface concentration-pH data show two maxima. The first is at the isoelectric point of the albumin while the second is at pH 9.5-10. The second maximum seems to be due to preferential adsorption of the higher molecular weight oligomers in the protein sample.

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