Authors Osaki, T. ; Renner, L. ; Herklotz, M. ; Werner, C.
Title Hydrophobic and electrostatic interactions in the adsorption of fibronectin at maleic acid copolymer films
Date 10.07.2006
Number 13865
Abstract Adsorption and desorption of fibronectin (FN) were investigated at thin films of alternating maleic acidcopolymers with octadecene (POMA) and with propene (PPMA). The hydrophobicity and charge density ofthe polymers were modulated by the choice of the comonomer. In consequence, the dominant forces betweenthe substrate and the protein were specified as hydrophobic interaction for POMA and electrostatic interactionfor PPMA. The adsorption kinetics were investigated in situ as variations of the optical thickness, adsorbedmass, and viscoelastic properties (detected by reflectometric interference spectroscopy and quartz crystalmicrobalance technique, respectively) while alterations of the electrosurface properties were derived fromsurface conductivity data and isoelectric points (by streaming potential/current measurements using a microslitelectrokinetic setup). The results demonstrate that the interfacial mode of adsorbed FN depends on thepredominant interactions: large amounts of FN were tightly bound to POMA by hydrophobic interactions. Incontrast, FN adsorbed on PPMA was concluded to attain an unfolded structure allowing for the "electrostaticmatching" of positively charged residues on FN with the maleic acid groups. This conclusion was supportedby the acidic IEP of 3.2 found for FN on PPMA and a significant reduction of the surface conductivity of theFN-covered polymer film, whereas FN on POMA showed an IEP of 4.2 (close to the intrinsic IEP of FN),indicating a stochastic orientation of the adsorbed protein.
Publisher Journal of Physical Chemistry / B
Citation Journal of Physical Chemistry / B 110 (2006) 12119-12124
Tags Protein Interactions at Cell Polymer Interfaces

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