Competitive Adsorption of Plasma Proteins Using a Quartz Crystal Microbalance

Abstract

Proteins that get adsorbed onto the surfaces of biomaterials immediately upon their implantation mediate the interactions between the material and the environment. This process, in which proteins in a complex mixture compete for adsorption sites on the surface, is determined by the physicochemical interactions at the interface. Competitive adsorption of bovine serum albumin (BSA), fibronectin (Fn), and collagen type I (Col I), sequentially and from mixtures, was investigated so as to understand the performances of different surfaces used in biomedical applications. A quartz crystal microbalance with dissipation was used to monitor the adsorption of these proteins onto two materials used in functional bone replacement, a titanium alloy (Ti6Al4V) and Ti6Al4V physisorbed with poly(sodium styrenesulfonate) [poly(NaSS)], and three controls, gold, poly(desaminotyrosyltyrosine ethyl ester carbonate) [poly(DTEc)], and polystyrene (PS). In experiments with individual proteins, the adsorption was the highest with Fn and Col I and the least with BSA. Also, protein adsorption was the highest on poly(NaSS) and Ti6Al4V and the least on poly(DTEc). In sequential adsorption experiments, protein exchange was observed in BSA + Fn, Fn + Col I, and BSA + Col I sequences but not in Fn + BSA and Col I + BSA because of the lower affinity of BSA to surfaces relative to Fn and Col I. Protein adsorption was the highest with Col I + Fn on hydrophobic surfaces. In experiments with protein mixtures, with BSA & Fn, Fn appears to be preferentially adsorbed; with Fn & Col I, both proteins were adsorbed, probably as multilayers; and with Col I & BSA, the total amount of protein was the highest, greater than that in sequential and individual adsorption of the two proteins, probably because of the formation of BSA and Col I complexes. Protein conformational changes induced by the adsorbing surfaces, protein-protein interactions, and affinities of proteins appear to be the important factors that govern competitive adsorption. The findings reported here will be useful in understanding the host response to surfaces used for implants.

Enhancement of plasma protein adsorption and osteogenesis of hMSCs by functionalized siloxane coatings for titanium implants

“…This behavior was enhanced in the case of MGTg substrate due to the presence of epoxide groups on the surface, which may mediate the binding of these proteins. These findings show that the functional groups can selectively increase the adsorption of proteins, and corroborates the previously reported results . Moreover, studies with QCM‐D have revealed that an increase in the viscoelastic properties of the adsorbed Fn layer correlates to the unfolding of the molecule once is adsorbed on the surface, increasing the exposure of the RGD cell binding sites and in consequence enhancing the bioactivity of the protein .…”

“…While BSA, because of its non-specific adsorption, displays lower affinity toward coated surfaces, Fbg and Fn do not. 45 Opposite effect was observed for the adsorption profile of Fbg, Fn, and Col I, where MGTg in spite of being slightly smoother than the other surfaces, adsorbed higher amounts of protein. More interestingly, the proteins involved in the subsequent cell attachment process due to their cell binding domains, such as Fn and Col I, adsorbed preferably onto developed siloxane coatings compared to Ti control.…”

“…This may suggest that this protein has not specificity to any given surface and it adsorbs equally onto any substrate forming a compact monolayer where the only decisive parameter is the available surface area for the adsorption. While BSA, because of its non‐specific adsorption, displays lower affinity toward coated surfaces, Fbg and Fn do not . Opposite effect was observed for the adsorption profile of Fbg, Fn, and Col I, where MGTg in spite of being slightly smoother than the other surfaces, adsorbed higher amounts of protein.…”

“…These findings show that the functional groups can selectively increase the adsorption of proteins, and corroborates the previously reported results. 45,49 Moreover, studies with QCM-D have revealed that an increase in the viscoelastic properties of the adsorbed Fn layer correlates to the unfolding of the molecule once is adsorbed on the surface, increasing the exposure of the RGD cell binding sites and in consequence enhancing the bioactivity of the protein. 51,52 In this case, an increase of D and DD/Df values (Table IV), from 4.0 to 5.5 and from 6.8 to 9.4 respectively, was observed in the cases where protein was bound to silicon-based coatings compared to Ti; this indicates the formation of a more viscous layer, what may suggest an open conformation of the Fn molecule.…”

Adsorption and Exchangeability of Fibronectin and Serum Albumin Protein Corona on Annealed Polyelectrolyte Multilayers and Their Consequences on Cell Adhesion

“…FN adheres less tightly to the annealed PEMs as observed by gamma counting. [51][52][53] The selective increase of BSA adsorption upon annealing suggests that the extrapolation of the behavior of Adv. We can only hypothesize that the increase in hydrophilicity and the presence of very narrow fibrils in the PEM after annealing do not facilitate tight attachment of FN to the PEM.…”