Protein adsorption on chemically modified surfaces

Following the implantation of a biomaterial, the first event to occur at the tissue-material interface is protein adsorption. Once proteins have adsorbed to the surface of a material, cells no longer see the material, but only the protein coated surface layer. This adsorbed protein layer can mediate the type of cells that adhere to the surface, which ultimately can determine the type of tissue that develops. In this experiment, glass and polystyrene surfaces were chemically modified forming ionic, non-ionic, hydrophobic, and hydrophilic surfaces. The modified surfaces were incubated in a RPMI diluted serum solution. After incubation, a radioimmunoassay was used to quantify the exposed proteins adsorbed onto the surface of the material. In general, albumin, complement C3 (C3), fibronectin (FN) and vitronectin (VN) competitively adsorbed to the modified surface in a similar fashion, whereas IgG adsorption was the opposite. The hydrophobic surfaces had higher adsorbance of the adhesion proteins (C3, FN and VN) compared to higher adsorption of albumin and IgG onto the hydrophilic surfaces. The surface mobility of the silane modified surfaces also affected the adhesion of proteins. The differences seen in protein adsorption did not directly correlate to monocyte adhesion and Foreign Body Giant Cell (FBGC) development on these surfaces.