Effects of Lubricant Composition on Adsorption Behavior of Proteins on Rubbing Surface and Stability of Protein Boundary Film

Abstract

Polyvinyl alcohol (PVA) hydrogel is one of the candidate materials for artificial cartilage. In previous research, it was found that the structure of protein boundary film is important essence for wear reduction of PVA hydrogel, and the stability of protein boundary film changes with relative ratio and total concentration of proteins. In this study, the behavior of protein adsorption on the glass surface rubbed with PVA hydrogel was observed by using total internal reflection fluorescence microscopy (TIRFM). Amount of adsorbed proteins under rubbed condition increased compared to those under statically immersed condition. In lubricant in which a stable protein boundary film was formed, the amount of adsorbed proteins in bottom layer of protein boundary film increased significantly with an increase of sliding distance. In addition, the ratio of adsorbed immuno globulin G (IgG) to albumin was higher than that in lubricant in which an exfoliative protein boundary film was formed. These results indicate that the formation of bottom layer mainly composed of γ-globulin is a critical element to form a stable boundary film, and the friction-induced enhancement of forming protein boundary film may occur in lubricant with appropriate protein constituents.

Influence of synovia constituents on tribological behaviors of articular cartilage

“…In binary protein solutions with coexistence of albumin and -globulin, the relative ratio and concentration of proteins had an intense influence on adsorbed film formation [29]. Furthermore, the observation of adsorbed molecules in the evanescent field within about 200 nm from surface by using the total internal reflection fluorescence (TIRF) microscopy indicated in binary protein solutions that the bottom layer of stable protein adsorbed film is mainly composed of -globulin and the friction-induced enhancement of forming protein adsorbed film occurs in lubricant with appropriate protein composition [30,31]. The competitive adsorption of albumin and -globulin appears to affect these behaviors as indicated in study of adsorption and desorption of both proteins with TIRF spectroscopy by Tremsina et al [32].…”

In situ measurements of thin films in bovine serum lubricated contacts using optical interferometry

“…The layer can be composed of adsorbed denatured proteins or another type of protein, for example, γ-globulin having a higher adsorption force. Generally, the problems of different albumin and γ-globulin adsorption are considerably complicated, especially for BS fluid, as is interpreted in Nakashima et al 28 and Yarimitsu et al 33,34…”

Biphasic and boundary lubrication mechanisms in artificial hydrogel cartilage: A review

“…For sliding pair of spherical PVA FT hydrogel specimen as 2-mm-thick layer and cover glass in single or binary protein solutions containing fluorescence-labeled albumin or immunoglobulin G (IgG), the adsorption behaviors of proteins were observed in the evanescent field within about 200 nm from surface using the total internal reflection fluorescence microscopy. 71 In these rubbing tests in thin film boundary lubrication conditions without HA with theoretical film thickness, h min = 0.025 µm, it is noted that the bottom layer of stable protein adsorbed film is mainly composed of γ-globulin and the friction-induced enhancement of forming protein adsorbed film occurs in lubricant with appropriate protein composition. In HA solution with h min = 0.207 µm, 72 adsorption of HA on rubbing surface is enhanced by coexistence with γ-globulin, and gel-like films derived under coexistence of HA and γ-globulin appear to contribute to lowering of friction.…”