Advanced chitosan-carbon nanotubes / hydroxyapatite nanocomposites for application in bone regeneration

Bone research benefits from recent developments of advanced composites combining polymers and solid nanoparticles. Here, we investigate composites comprising chitosan, hydroxyapatite, and carbon nanotubes, providing insights into the polymer-nanoparticle interactions and the relationships of these compounds with water. These results were combined with assays performed with pre-osteoblastic cells. We observe that chitosan’s amine moieties hardly participate in the polymer/nanoparticles interactions, and the nanotubes barely contribute to the formation of interfacial water populations. Conversely, hydroxyapatite directly affects the behavior of interfacial and bulk-like water within the composite due to the hydrophilic character of these particles and their gradual degradation within the chitosan network. In the biological assays, the chitosan/hydroxyapatite composite induces a fast cellular response followed by a negative effect, likely because of a meaningful release of ions to the media. However, adding nanotubes to the formulation mitigates this effect and enables a more sustainable, positive impact on the cells.