PM-IRRAS Investigation of the Interaction of Serum Albumin and Fibrinogen with a Biomedical-Grade Stainless Steel 316LVM Surface

Abstract

Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) was applied to investigate the interaction of bovine serum albumin (BSA) and fibrinogen with a biomedical-grade 316LVM stainless steel surface, in terms of the adsorption thermodynamics and adsorption-induced secondary structure changes of the proteins. Highly negative apparent Gibbs energy of adsorption values revealed a spontaneous adsorption of both proteins onto the surface, accompanied by significant changes in their secondary structure. It was determined that, at saturated surface coverages, lateral interactions between the adsorbed BSA molecules induced rather extensive secondary structure changes. Fibrinogen's two coiled coils appeared to undergo negligible secondary structure changes upon adsorption of the protein, while large structural rearrangements of the protein's globular domains occurred upon adsorption. The secondary structure of adsorbed fibrinogen was not influenced by lateral interactions between the adsorbed fibrinogen molecules. PM-IRRAS was deemed to be viable for investigating protein adsorption and for obtaining information on adsorption-induced changes in their secondary structures.

Application of Polarization Modulation Infrared Reflection Absorption Spectrosocpy Under Electrochemical Control for Structural Studies of Biomimetic Assemblies

“…At surfaces of biomaterials a successful bio integration process depends to a large extent on the adsorption of proteins on their surfaces [1,97]. The adsorption of blood plasma proteins such as albumin, immunoglobulins or fibrinogen is of great importance at the surface of blood-contacting implant materials [162]. In the case of bone-substituting implants the adsorption of proteins from the extracellular matrix such as collagen, elastin, fibronectin or laminin is a crucial step in the bio integration process [1,97].…”

“…The adsorption of proteins depends on properties of a solid surface, the nature of a protein and the solution conditions such as the concentration of the electrolyte, ionic strength, pH or temperature. The adsorption process may lead to changes in the secondary structure of the adsorbed protein [123,162]. In order to understand, at the molecular level, the adsorption process of proteins the application of surface characterizing analytical techniques sensitive to the protein structure in situ at the solid|liquid interface is required.…”

“…Indeed, IRS is a superb technique allowing studies of the secondary structure of proteins and its changes [14,15,163,164]. PM IRRAS is sensitive to the structure of species adsorbed at a solid surface and it has been used to study the adsorption of proteins at stainless steel|air [162] and gold|air interfaces [165,166]. The analysis of the amide I modes of PM IRRA spectra of albumin adsorbed on the stainless steel surface show that the increase in the surface concentration of the adsorbed protein leads to a gradual loss of the helical structure and unfolding of the adsorbed protein [162].…”

“…PM IRRAS is sensitive to the structure of species adsorbed at a solid surface and it has been used to study the adsorption of proteins at stainless steel|air [162] and gold|air interfaces [165,166]. The analysis of the amide I modes of PM IRRA spectra of albumin adsorbed on the stainless steel surface show that the increase in the surface concentration of the adsorbed protein leads to a gradual loss of the helical structure and unfolding of the adsorbed protein [162]. Fibrinogen is a large dimer protein composed of two hydrophobic outer domains (D) which are bound to a central hydrophilic domain (E) via two coiled -helix coils [167].…”

“…In a native fibrinogen the content of -helix secondary structure is close to 30-37% and -sheet to 21-30%. Figure 18 shows the content secondary structure elements ( -helix and -sheet) determined from the analysis of the amide I mode of PM IRA spectra of fibrinogen adsorbed on the stainless steel surface [162]. In fibrinogen adsorbed on the implant surface the content of -helical structure remains at same level as in the native protein and is equal to 30% ( Figure 18A).…”