Protein adsorption at solid-liquid interfaces

Protein adsorption at solid-liquid interfaces is important in a variety of biomedical applications. The mechanisms of protein adsorption, however, have not been clearly understood yet. The goal of this research was to achieve further understanding on the protein adsorption behavior at solid-liquid interfaces. Computer simulation of protein adsorption as well as experimental methods were used in the research. The potential interaction energy, the hydrophobic interaction energy, and the molecular orientations of adsorbed proteins on polymer surfaces at the initial contact stage were examined using a computer simulation approach. Two FORTRAN computer programs were developed for the study. It was found that the potential interaction energy and the hydrophobic interaction energy were dependent on the orientations of a protein on polymer surfaces. The total interaction energy for proteins on the hydrophobic polymer surface is lower than that on the hydrophilic polymer surface. A new enzyme digestion approach was developed to study the structural changes of adsorbed fibrinogen on glass. The Lys 133-Asp 134 region on $\beta$ chain of the adsorbed fibrinogen on glass was found to be imbedded inside the tertiary structure of the fibrinogen. The effects of the surface-hydrophobicity on conformational changes of the adsorbed fibrinogen was examined using a FTIR-ATR technique. The $\alpha$-helix of fibrinogen was found to change to the unordered structure upon adsorption on solid surfaces. The adsorbed fibrinogen underwent greater conformational changes as the solid surface hydrophobicity increased. Protein adsorption isotherms on hydrophobic and hydrophilic surfaces were studied using a radio-labelling technique. The protein adsorption was found to be stronger on hydrophobic solid surfaces than on hydrophilic ones. This observation is in agreement with the compute simulation study. The combination of computer simulation and protein adsorption experiments has provided new insights into the protein adsorption behavior