Fibronectin and Bovine Serum Albumin Adsorption and Conformational Dynamics on Inherently Conducting Polymers: A QCM-D Study

摘要

Quartz crystal microbalance with dissipation monitoring (QCM-D) was employed to characterize the adsorptionnof the model proteins, bovine serum albumin (BSA) and fibronectin (FN), to polypyrrole doped with dextran sulfate (PPy−DS)nas a function of DS loading and surface roughness. BSA adsorption was greater on surfaces of increased roughness and was abovenwhat could be explained by the increase in surface area alone. Furthermore, the additional mass adsorbed on the rough films wasnconcomitant with an increase in the rigidity of the protein layer. Analysis of the dynamic viscoelastic properties of the proteinnadlayer reveal BSA adsorption on the rough films occurs in two phases: (1) arrival and initial adsorption of protein to thenpolymer surface and (2) postadsorption molecular rearrangement to a more dehydrated and compact conformation thatnfacilitates further recruitment of protein to the polymer interface, likely forming a multilayer. In contrast, FN adsorption wasnindependent of surface roughness. However, films prepared from solutions containing the highest concentration of DS (20 mgmL) demonstrated both an increase in adsorbed mass and adlayer viscoelasticity. This is attributed to the higher DS loading innthe conducting polymer film resulting in presentation of a more hydrated molecular structure indicative of a more unfolded andnbioactive conformation. Modulating the redox state of the PPy−DS polymers was shown to modify both the adsorbed mass andnviscoelastic nature of FN adlayers. An oxidizing potential increased both the total adsorbed mass and the adlayer viscoelasticity.nOur findings demonstrate that modification of polymer physicochemical and redox condition alters the nature of protein−npolymer interaction, a process that may be exploited to tailor the bioactivity of protein through which interactions with cells andntissues may be controlled.