Fibronectin and collagen-based biomimetic surfaces to improve cell-material interactions for biomedical applications

The lack of donors for grafts has led to the development of new strategies, based on biomaterials and tissue engineering. For both approaches, a key challenge is the control of cell-material interactions, which can be addressed by modifying the physical and/or chemical properties of material surfaces. A biomimetic way to do it is the adsorption of molecules from the extracellular matrix. In this work, two proteins, collagen (Col) and fibronectin (Fn), were chosen as building blocks to create well-organized biointerfaces to improve interactions with cells. To design biomimetic surfaces, layer-by-layer (LbL) deposition was compared to simultaneous adsorption of both proteins. The influence of the buffer composition, of a polyethyleneimine anchoring layer and of collagen denaturation on LbL assembly was studied. The results showed that true LbL building was not obtained by assembly of Col and Fn. However, multilayers were built and results showed that an anchoring layer allowed thicker films to be obtained, and that Hepes buffer allowed obtaining the most regular assembly. Moreover, comparison with simultaneous adsorption revealed interesting features. Films obtained by simultaneous adsorption were of the same thickness, or even thicker than those prepared by LbL, and they presented a different morphology, with more Col fibrils and a lower contact angle. Adipose derived mesenchymal stem cells were cultured on films obtained by both deposition methods, in Hepes, with or without anchoring layer. All the protein films supported cell adhesion and growth better than pure polystyrene. The main influence observed on cells was the one of the anchoring layer, which decreased proliferation rate but improved osteogenic differentiation. Biointerfaces were thus designed based on Col and Fn which influence cell behavior. It may open the way to new strategies for tissue engineering applications.