VOLUMETRIC INTERPRETATION OF PROTEIN ADSORPTION KINETICS

Open Access
Author:
Barnthip, Naris
Graduate Program:
Materials Science and Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
February 24, 2009
Committee Members:
  • Erwin A Vogler, Dissertation Advisor
  • Erwin A Vogler, Committee Chair
  • Paul Wencil Brown, Committee Member
  • Ralph H Colby, Committee Member
  • Christopher Alan Siedlecki, Committee Member
Keywords:
  • Interfacial Energetics
  • Protein Adsorption
  • Adsorption Kinetics
  • Adsorption Competition
  • Interphase
  • Surface
Abstract:
Protein adsorption is believed to be a very important factor ultimately leading to a predictive basis for biomaterials design and improving biocompatibility. Standard adsorption theories are modified to accommodate experimental observations. Adsorption from single-protein solutions and competitive adsorption from binary solutions are mainly considered. The standard solution-depletion method of measuring protein adsorption is implemented with SDS-gel electrophoresis as a multiplexing, separation-and-quantification tool to measure protein adsorption to hydrophobic octyl sepharose (OS) adsorbent particles. Standard radiometric methods have also been used as a further check on the electrophoresis method mentioned above for purified-protein cases. Experimental results are interpreted in terms of an alternative kinetic model called volumetric interpretation of protein adsorption. A partitioning process between bulk solution and a three-dimensional interphase region that separates bulk solution from the physical adsorbent surface is the concept of the model. Protein molecules rapidly diffuse into an inflating interphase that is spontaneously formed by bringing a protein solution into contact with a physical surface, then follows by rearrangement of proteins within this interphase to achieve the maximum interphase concentration (dictated by energetics of interphase dehydration) within the thinnest (lowest volume) interphase possible. An important role of water in protein adsorption is emphasized and supported by this model. The fundamental aspects including the reversibility/irreversibility of protein adsorption, the multilayer adsorption, the applicability of thermodynamic/computational models, the capacity of protein adsorption, and the mechanism of so called Vroman effect are discussed and compared to the conventional theories. Superhydrophobic effect on the adsorption of human serum albumin is also examined.