Question

How do proteins bind to a surface, and what role does the primary sequence play in protein-surface interactions?

Answer 1

The behavior of proteins at surfaces plays a vital role in determining the nature of the tissue-implant interface. Adsorbed proteins a¤ect blood coagulation, complement activation, and bacterial and cell adhesion. Furthermore, adsorbed proteins can influence biomaterial surface properties and degradation. The basic principles of protein adsorption in terms of protein and surface characteristics that affect the behavior of proteins at solid surfaces are explained below.

The surfaces of synthetic biomaterials (e.g., polymers, metals, and ceramics) are generally not bioactive themselves. Rather, surface bioactivity is provided by the proteins that adsorb to the biomaterial surface following exposure of the surface to biological fluids. The types and the amounts of proteins adsorbed determine the types and surface density of the bioactive sites that may be available for cell interactions, and the orientation, conformation, and packing density of the adsorbed proteins determine whether the available bioactive sites are presented in a manner such that they can be recognized by the membrane-bound receptors of cells as they interrogate the adsorbed protein layer. Accordingly, to control cellular response, it is important to first understand how surface chemistry and surface topology influence the formation of the adsorbed protein layer and the bioactive sites presented by this layer. Although the understanding of protein adsorption to biomaterial surfaces is still far from complete, research over the past several decades has led to a general understanding of the complex and multifaceted processes involved in the interactions between proteins and surfaces. Protein structure is first presented to establish a framework from which protein adsorption behavior can begin to be understood. The protein adsorption behavior to biomaterial surfaces is presented, initially for the relatively simple case involving protein adsorption from single-component protein solutions, and then for the more complex situation involving competitive adsorption from multicomponent protein solutions.