Influence of Chemical Conjugation Strategies on Fibronectin's Bioactivity

Abstract

Since thirty years, efforts were put forward to engineer materials that could be used to build up biomedical devices that have to come in contact with human tissues. The first devices that were developed were designed to reproduce the basic functions of the tissue or organ that they were intended to replace. For example, the first designs of arterial prostheses were made from materials that can be formed as tubes with sufficient mechanical properties and chemical stability, to withstand the pulsatile blood pressure for many years without failure. Only few concerns were raised regarding the interaction between the material and the physiological environment. Nowadays, the common strategy consists in developing materials that are likely to proactively interact with their environment.For instance, one idea is to coat the surface of biomaterials with proteins of the extracellular matrix, therefore promoting cell adhesion and proliferation. Fibronectin is one of these proteins and has been the subject of several investigations as to its potential to be used to promote cell/material interaction once conjugated to the surface of biomaterials. In this context, the aim of this study was to compare two strategies of FN immobilization in regards to the amount of bound FN and its biological activity. Two heterobifunctional cross-linkers were used to conjugate FN to ammonia plasma-treated PTFE: glutaric anhydride (GA) and Sulfo-succinimidyl 4-[p-maleimidophenyl] butyrate (sulfo-SMPB). In addition, we have also investigated the influence of adding either a hydrophilic or hydrophobic spacer between the protein and the surface on the protein bioactivity. On one hand, our results demonstrated that fibronectin RGD sequences are more available when the protein is conjugated through its lysine moieties. On the other hand, an hydrophobic spacer between fibronectin and the biomaterial surface is also likely to promote the protein bioactivity.