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Interaction of Proteins/Polysaccharides with Polymeric Surfaces

We have shown that proteins can change their internal (secondary) structure by passively adsorbing onto a hydrophobic polymeric surface and that polysaccharides exhibit a structural change on exposure to increasing salt solution.

Objective:

Develop polymeric surfaces that exhibit protein and polysaccharide resistance (low adsorption and adhesion) for bioseparations and marine fouling, respectively.

Approaches:

Measure adhesion between proteins/polysacharrides and heterogeneous (films and membranes) and homogeneous (self-assembled monolayers, SAMS's) polymeric substrates. Use atomic force microscopy to measure intermolecular forces (energy-distance curves and adhesion) between covalently bound proteins and polymeric or SAM substrates. See Figure 1, Figure 2, and Figure 3.
Measure kinetic and thermodynamic effects of adsorption on polymers and secondary structural transitions of proteins. Use attenuated total reflection Fourier transform infrared spectroscopy with a newly developed optimization routine for predicting the secondary structural changes of proteins in free solution and in the adsorbed state. See Figure 4 and Figure 5.
Use quartz-crystal microbalance with dispersion to measure protein adsorption kinetics and surface viscosity.

Relevant Publications:

Koehler, J. A., Ulbricht, M. and Belfort, G. (1997) Intermolecular forces between proteins and polymer films with relevance to filtration, Langmuir 13 (15) 4162-4171.
Frank, B. and Belfort, G. (1997) Intermolecular forces between extrapolysaccharides, Langmuir,13, 6234-6240.
Koehler, J. A., Ulbricht, M. and Belfort, G. (2001) Intermolecular forces between a protein and a hydrophillic polysulfone film with relevance to filtration. Langmuir 16, 10419-10427.
Frank, B. F. and Belfort, G (2001) Atomic Force Microscopy for Low Adhesion Surfaces: Thermodynamic Criteria, Critical Surface Tension and Intermolecular Forces, Langmuir, 17, (6) 1905-1912.
Sethuraman, A., Vedantham, G., Gotto, M., Przybyccien T., and Belfort, G (2003) Protein unfolding at interfaces: Slow dynamics of a-helix to b-sheet transition, submitted.

Sample results:

See Figures 1 - 5