Protein Adsorption to Hydrophobic Surfaces
Open Access
- Author:
- Krishnan, Anandi
- Graduate Program:
- Bioengineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- June 17, 2005
- Committee Members:
- David Lawrence Allara, Committee Member
Christopher Alan Siedlecki, Committee Chair/Co-Chair
Erwin A Vogler, Committee Chair/Co-Chair
William O Hancock, Committee Member
Kelly Brown, Committee Member - Keywords:
- Blood Proteins
Tensiometry
Adsorption
Self-Assembled Monolayers
Quartz Crystal Microbalance - Abstract:
- Adsorption energetics of diverse purified proteins as well as whole-blood plasma and serum (aqueous-buffer) solutions were remarkably similar at two hydrophobic surfaces – water-air (liquid, vapor, LV) and solid-water (solid-liquid, SL). A ‘Traube-rule-like’ progression (molar concentration required to reach a specified spreading pressure decreases with increasing MW) was observed at both hydrophobic surfaces (LV and SL) for globular proteins spanning three-orders-of-magnitude in molecular weight (MW). Collective results from the observed ‘Traube-rule-like’ progression in interfacial-tension reduction, an invariant partition coefficient , and a constant Gibbs’ surface excess (as a measure of amount of protein adsorbed) all imply that water controls the energetics of the protein adsorption process. Hence, protein adsorption to hydrophobic surfaces has more to do with water than the proteins themselves. A relatively straightforward theory of protein adsorption predicated on the interfacial packing of hydrated spherical molecules with dimensions scaling as a function of MW accounts for the essential physical chemistry of protein adsorption and rationalizes significant experimental observations. From this theory, it is evident that displacement of interfacial water by hydrated proteins adsorbing from solution places an energetic cap on protein adsorption to hydrophobic surfaces. This phenomenon is generic to all proteins. As a consequence, protein adsorption is not found to vary significantly among diverse protein types. Variations from this general trend may reflect deviations in protein geometry from simple spheres and/or tendency of some proteins to adopt a more spread/compact configuration in the adsorbed state.