Atomic force microscopy evidence for conformational changes of fibronectin adsorbed on unmodified and sulfonated polystyrene surfaces

Abstract

The effect of polystyrene surface polarity on the conformation of adsorbed fibronectin (FN) has been studied with atomic force microscopy. We demonstrated that bare sulfonated and nonsulfonated polystyrene surfaces featured similar topographies. After the FN adsorption, direct comparison of both types of substrata revealed drastically different topographies, roughness values, and also cell-adhesive properties. This was interpreted in terms of FN conformational changes induced by the surface polarity. At high-solute FN concentrations the multilayer FN adsorption took place resulting, for the sulfonated substratum, in an increase of surface roughness, whereas for the nonsulfonated one the roughness was approximately stable. Conversely, the FN conformation characteristic for the first saturative layer tended to be conserved in the consecutive layers, as evidenced by height histograms. The height of individual FN molecules indicated, consonantly with the derived thickness of the adsorbed protein layer (the latter value being 1.4 nm and 0.6 nm, respectively, for an unmodified and sulfonated polystyrene surface), that molecules are flattened on polar surfaces and more compact on nonsulfonated ones. It was also demonstrated that the FN adsorption and conformation on polymeric substrata, and hence the resultant cell-adhesive properties, depended on the chemistry of the original surface rather than on its topography. Our results also demonstrated the ability of surface polarity to influence the protein conformation and its associated biological activity.

Electrospray deposition in vacuum as method to create functionally active protein immobilization on polymeric substrates

“…An increase in roughness was observed from Ra = 2.9 ± 0.5 nm (before deposition) to Ra = 3.5 ± 0.3 nm (after fibronectin deposition). A comparable roughness parameter approach was previously used in similar work to confirm protein deposition on a similar substrate demonstrating how variations in substrate materials can influence fibronectin deposition and activity [30,31]. In Fig.…”

“…The deposition of fibronectin was Previous studies [30,32,33] have demonstrated that proteins may be deposited with functional integrity using various methods to maintain protein stability. In this study the assessment of protein function has been extended by studying the cellular response to electrospray deposits.…”

Interaction of PC-3 cells with fibronectin adsorbed on sulfonated polystyrene surfaces

“…surface roughness), and on the environmental conditions (e.g. pH value, ionic strength and temperature) [9][10][11][12][13][14][15]. As a result of adsorption, FN conformation can become compact or extended, depending on physicochemical conditions.…”

“…As a result of adsorption, FN conformation can become compact or extended, depending on physicochemical conditions. It has been observed that adhesion of normal and cancer cells to substrate surfaces containing chemical groups with a negative charge (-SO 3 H, -OH, -COOH) or a positive charge (-NH 2 ) depends on surface wettability and the conformation of the protein molecule on the surface [9,[11][12][13][14][15][16][17][18][19]. Fibronectin adsorbed on strongly hydrophilic polystyrene surfaces, in contrast to the adsorption on hydrophobic surfaces, is characterized by extended, biologically active conformation with the unfolded cellbinding domain (CCBD), which stimulates not only the early phase of adhesion, but also the cell spreading process [13,14,20,21].…”

“…It has been observed that adhesion of normal and cancer cells to substrate surfaces containing chemical groups with a negative charge (-SO 3 H, -OH, -COOH) or a positive charge (-NH 2 ) depends on surface wettability and the conformation of the protein molecule on the surface [9,[11][12][13][14][15][16][17][18][19]. Fibronectin adsorbed on strongly hydrophilic polystyrene surfaces, in contrast to the adsorption on hydrophobic surfaces, is characterized by extended, biologically active conformation with the unfolded cellbinding domain (CCBD), which stimulates not only the early phase of adhesion, but also the cell spreading process [13,14,20,21]. The polystyrene surfaces used in the present work have been modified according to the original method developed by Kowalczyń-ska and Kamiński [22], which unlike other methods of surface modification [16,[23][24][25], is mild and highly efficacious, making it possible to eliminate the harmful hydrolyzing effect of sulfuric acid.…”