Production of nanostructured ECM-like biointerfaces incorporating bioactive hydroxyapatite nanocrystals

Most of the scientists working in the field of tissue regeneration focus their research on creating a scaffold that allows cells to adhere, proliferate and differentiate. One of the most promising methods up to now consists in mimicking the natural environment of cells, namely the extracellular matrix (ECM). In this work, falling into the bone regeneration field, a new method is presented to synthesise a nanostructured biointerface mimicking the ECM of bone. It is composed of nanotubes made of collagen (Col) and hyaluronic acid (HA), two natural components composing the ECM in the human body. Those nanotubes are synthesised by combining the membrane templated and the layer-by-layer (LbL) methods. Intersected nanotubes are obtained by using track-etched polycarbonate (PC) membranes. In a previous study, mechanically stable systems made of such nanotubes were successfully synthesised by D. Lefèvre by the incorporation of SiO2 particles. In an attempt to increase the biocompatibility of those systems and to keep their mechanical properties, SiO2 particles were replaced by another ceramic present in the ECM of bone, the hydroxyapatite (HyAp). The incorporation of commercially available HyAp nanocrystals within intersected (Col/HA) nanotubes system appeared to be unsuccessful. Indeed, HyAp was discovered to aggregate at the pH used for the LbL synthesis of nanotubes making it difficult to incorporate into the system. However, by in situ nucleation of HyAp onto the (Col/SiO2)(Col/HA)n system, a crust of HyAp was successfully deposited on the system. In this way, the formation of a biointerface made of intersected nanotubes composed of natural components was well achieved. Still, the mechanical properties have to be improved as the intersected nanotubes of the biointerface collapse