Investigation of Silica, Polypropylene and Titanium surfaces before and after fibrinogen adsorption

Fibrinogen (FB) is a protein that plays a crucial role in lots of processes in the organism, in particular for what concerns the interaction between implants and tissues, through the formation of a substratum which is essential for adhesion and aggregation of cells and/or platelets (clotting). This process may lead to the full integration of the implant or to chronic inflammation which determines the subsequent implant failure. During biomaterial implantation, several steps occur including, first of all, protein adsorption which strongly depends on surface features such as wettability, charge, topography and roughness. Proteins (such as fibrinogen) may assume various orientations and may adsorb in variable amount and, as a consequence, may undergo different structure variations, eventually denaturing, i.e. in case of hydrophobic surfaces or hydrophilic ones with a high density of charged functional groups. For this reason, fibrinogen adsorption is studied in this thesis on two model surfaces with different wettability that are silica (SiO2) as a model of hydrophilic surfaces and polypropylene (PP) as a model of hydrophobic ones, both biocompatible and usable in biomedical applications. They are also compared to a Titanium alloy (Ti6Al4V, defined as Ti64) and to a chemical-treated Titanium alloy (CT), characterized by a complex surface (multiscale surface topography with a nanotexture overlapped to a micro-roughness), a high density of acidic OH groups, and a bioactive behavior. All samples were properly characterized by several techniques and tested under different conditions, with and without fibrinogen, to identify their surface behavior and features, both qualitatively (i.e. through imaging techniques) and quantitatively, characterizing the amount of the adsorbed protein, its conformation, and type of bonding with the surface, in view to predict and understand the material interaction with the blood. The final purpose is to design cutting-edge biomaterials, extending their use in the biomedical field.