Interaction of Hyaluronic Acid with CoCr Alloy Under Immersion and Wear–Corrosion Processes

Abstract

In this work, electrochemical and chemical changes induced by immersion and wear–corrosion processes of CoCr/CoCr couple in phosphate buffer solution (PBS) with 0.3% hyaluronic acid (PBS-HA) have been studied. Electrochemical characterization of CoCr surfaces in PBS-HA was performed by the measurement of the corrosion potential, electrochemical impedance spectroscopy, and scanning kelvin probe. Wear–corrosion tests were carried out in PBS-HA in a pin-on disk tribometer where 5N was loaded on the CoCr cylindrical pin in contact with CoCr disk rotating at 120 rpm of 10 mm diameter. Chemical composition of the CoCr surfaces after wear–corrosion tests was assessed by X-ray photoelectron spectroscopy (XPS). The electrochemical results on CoCr surfaces in hyaluronic acid solution revealed that the hyaluronic acid accelerates the formation of a stable and resistant passive film on the CoCr surfaces after few hours of immersion. XPS results showed that continuous sliding under immersion in PBS-HA causes the loss of the Cr oxides [forming preferentially Cr(OH)3] and a slight increase in Co(II) species in the passive film. These changes in the chemical composition were accompanied by the increase, at least twofold, in C and O and calcium phosphate compounds on the outer CoCr surfaces.