Protein adsorption of human serum albumin at solid/liquid interfaces as monitored by electron spin resonance spectroscopy

In this thesis, the adsorption of human serum albumin (HSA) on solid surfaces in defined buffers was followed by electron spin resonance (ESR) spectroscopy to determine conformational changes of the protein as a result of the adsorption under varying conditions of pH. Glass, polystyrene, and polystyrene-butadiene were the surfaces chosen based on their application in cell immobilization useful in promoting cell growth or for their use in biomedical implants and prosthetics. Monitoring of the protein conformation was achieved by labelling the HSA protein with a 4-maleimido-tempo (MT) molecule, a stable free radical with a single unpaired electron which supplies the source of ESR signals. This spin label was covalently bound to the single free sulfhydryl group (Cys 34 residue) on the HSA molecule and reported on the activity of the protein in its immediate environment.;Immobilization of the MT spin label molecule increased as a result of adsorption onto glass, polystyrene, and polystyrene-butadiene beads in comparison to the free protein in solution. However, the point of attachment between the protein and the surface substrate was not in the immediate vicinity of the spin label for any of the surfaces studied.;Polystyrene immobilized HSA-MT to a larger extent than glass or polystyrene-butadiene, reflecting a more avid association between this substrate and the protein. The immobilization of the protein as a consequence of adsorption to the glass and polystyrene-butadiene was smaller, probably as a result of electrostatic repulsions between the negatively charged protein and the negatively charged surfaces. (Abstract shortened by UMI.)...