Dynamic Assessment of Fibrinogen Adsorption and Secondary Structure Perturbation

Fibrinogen is a protein being of prime importance for the initiation of clotting and thrombus formation, readily adsorbed onto surfaces presenting both hydrophilic and hydrophobic nature. The mechanism of adsorption, and thus the final presentation of this protein are therefore important for subsequent involvement for, for example, platelet adhesion. Biological activity can be controlled through careful consideration of material design; here we report kinetic assessment of fibrinogen adsorption onto plasma polymerised allylamine (hydrophilic) and hexane (hydrophobic) surfaces, using FTIR-ATR to inform on kinetics of adsorption, secondary structure evaluation, and orientational variation. Fibrinogen was found to respond differently to these two surfaces, adsorbing more rapidly to hydrophilic surfaces and losing an ordered secondary structure over a much longer timescale compared to hydrophobic surfaces. 1. Introduction The interface between biological fluids and the surface of a material is of the utmost importance when considering the longevity and function of materials in such environments. Biological activity at this interface is dictated by the ability of the surface to support the adsorption of proteinatious materials. Adsorption of biological species (e.g., proteins/peptides) occurs rapidly upon interaction of the biological fluid with numerous surface cues acing in synergy, such as chemical functionality and nano-scale features, to control adsorption characteristics and activity of bound species. Surface engineering therefore plays a major part in the advancement of material function; the aim within the biological sciences is the production of designer materials that specifically control biological responses. Such materials have far-reaching impact, from the success of implantable or point-of-care biotechnology, designer materials for the reduction of hospital acquired infections, to advanced cell culture materials for optimised stem cell expansion and guided differentiation. The design of advanced materials towards achieving these goals is therefore of high commercial impact and of considerable economic and social value. Protein molecules rapidly accumulate on surfaces, starting milliseconds after contact between the solid and biofluid. This is a highly dynamic process wherein protein molecules bind, rearrange, and detach. It is well accepted that surface parameters presented by materials dictate how rapidly and to what extent specific proteins adsorb; each parameter, such as chemical functionality or nano-structure, acts synergistically giving