Fibronectin, bovine serum albumin adsorption, 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 adsorption of the model proteins, bovine serum albumin (BSA), fibronectin (FN), to polypyrrole doped with dextran sulfate (PPy-DS) as a function of DS loading, surface roughness. BSA adsorption was greater on surfaces of increased roughness, was above what could be explained by the increase in surface area alone. Furthermore, the additional mass adsorbed on the rough films was concomitant with an increase in the rigidity of the protein layer. Analysis of the dynamic viscoelastic properties of the protein adlayer reveal BSA adsorption on the rough films occurs in two phases: (1) arrival, initial adsorption of protein to the polymer surface, (2) postadsorption molecular rearrangement to a more dehydrated, compact conformation that facilitates further recruitment of protein to the polymer interface, likely forming a multilayer. In contrast, FN adsorption was independent of surface roughness. However, films prepared from solutions containing the highest concentration of DS (20 mg/mL) demonstrated both an increase in adsorbed mass, adlayer viscoelasticity. This is attributed to the higher DS loading in the conducting polymer film resulting in presentation of a more hydrated molecular structure indicative of a more unfolded, bioactive conformation. Modulating the redox state of the PPy-DS polymers was shown to modify both the adsorbed mass, viscoelastic nature of FN adlayers. An oxidizing potential increased both the total adsorbed mass, the adlayer viscoelasticity. Our findings demonstrate that modification of polymer physicochemical, redox condition alters the nature of protein-polymer interaction, a process that may be exploited to tailor the bioactivity of protein through which interactions with cells, tissues may be controlled.