Wettability versus electrostatic forces in fibronectin and albumin adsorption to titanium surfaces

Abstract

Although the enhancement of plasma protein adsorption to titanium ( Ti ) following wetting has been recognized, the relationship between wettability and electrostatic forces has remained unclear. Thus, we have carried out a series of studies to determine the role of wettability and electrostatic forces on protein adsorption. Titanium disks with different surfaces were wetted with a range of solutions, two of which contained divalent positive ions ( Ca and Mg ). Unwetted disks served as a control. Subsequently, the wetted disks were subjected to three treatment regimes: (1) incubation in human serum albumin (HSA) or human serum fibronectin (HSF); (2) drying the wetted disks, followed by incubation in HSA or HSF; and (3) following protein adsorption, the Ca originating in the wetting solutions was removed by divalent positive ions chelator treatment (EGTA), and the remaining quantities were assessed. The quantity of the adsorbed proteins was determined by ELISA. It was found that in the case of HSA, adsorption was enhanced by the wettability, the presence of Ca and Mg in the wetting solution, and the existence of rough surfaces. For HSF, the wettability and rough surfaces enhanced adsorption. The results demonstrate that in addition to wettability, the composition of the wetting solution affects the protein adsorption. While wetting reduces the time for the HSA and HSF adsorption to reach saturation, the electrostatic forces enhance the amount of HSA adsorption. Thus, the protein adsorption capacity of titanium rough surfaces can be selectively manipulated by changing of the wetting solution.