Chitosan–Hydroxyapatite Composite Chemical/Physical Crosslinking Scaffolds for Cell Cultivation

The development of biocompatible and mechanically flexible skeletal scaffolds is a significant challenge in modern regenerative medicine. In this study, we developed composite scaffolds based on biodegradable chitosan polymer and hydroxyapatite particles. We have shown for the first time that treatment with sodium hydroxide solution, which is often used to convert chitosan scaffolds into an insoluble form, can cause alkali sorption by hydroxyapatite particles. This has been demonstrated by our experiments. It has also been shown that the alkaline treatment of composite scaffolds increases the pH of the surrounding culture medium, reducing the viability of mesenchymal stromal cells by 60–70%. As an alternative to the processing of composite scaffolds using chitosan and hydroxyapatite, we propose heat treatment. This method allows us to produce stable scaffolds without affecting cell viability. Heat treatment promotes the formation of bonds between free amino groups in chitosan and phosphate groups in hydroxyapatite, as well as increasing the elasticity of the composite matrices in humid conditions.