Effect of chitosan structure and deposition time on structural and mechanical properties of chitosan-hydroxyapatite tubular-shaped electrodeposits for biomedical applications

Chitosan-hydroxyapatite tubular-shaped hydrogel structures have been successfully obtained by electrophoretic deposition. The deposits show great potential in the regeneration of tubular organs and tissues, in particular peripheral nerve tissue engineering. The mechanism for their formation has been investigated by studying the deposition yield from solutions differing in chitosan structure. The resulting deposit mass is higher for 95% deacetylated chitosan than one for 75% deacetylated chitosan in all analyzed time intervals. The longer the deposition time, the higher the deposit mass is observed up to 40 min. The performed elemental analysis sets the foundation for the understanding of the electrodeposition mechanism from chitosan-hydroxyapatite solution in lactic acid. It is suggested that protonation of chitosan ions and their attraction to H2PO4- groups on hydroxy-apatite particles in the acidic environment is a prerequisite to electrophoretic deposition. Upon application of an electric field, pH increases in the vicinity of the cathode, and the positively charged chitosan chain is neutralized. The chitosan-hydroxyapatite precipitation is accompanied by calcium carbonate deposition. Consequently, an insoluble chitosan-hydroxyapatite-calcium carbonate deposit is formed on the cathode surface. It is anticipated that the presented mechanism will provide insight into modeling deposit properties desired on an industrial scale.

Automated summary

Chitosan-hydroxyapatite tubular-shaped hydrogel structures have been obtained by electrophoretic deposition, showing great potential in peripheral nerve tissue engineering. The formation mechanism involves protonation of chitosan ions and their attraction to H2PO4- groups on hydroxy-apatite particles in an acidic environment, resulting in the deposition of an insoluble chitosan-hydroxyapatite-calcium carbonate deposit on the cathode surface. This understanding can provide insights for modeling desired deposit properties on an industrial scale.