Depositing an Apatite Coating in/on Massive Chitosan Porous Scaffolds by an Alternate Soaking Method

Abstract

We hope to improve the biological activity and the osteo-conductivity of a porous polymer scaffold by the deposition of a hydroxyapatite (HA) coating. We used an alternate soaking deposition method to prepare HA coating. A massive chitosan (Cs) porous scaffold was used as a deposition template and immersed alternately in calcium chloride and disodium hydrogen phosphate solutions. Finally, a hydroxyapatite coating was deposited in/on the massive chitosan porous scaffold. The compositions, micromorphology, porosity, inorganic deposition amount and compressive strength were characterized by XRD, FT-IR, SEM, porosity measurements, calcination and a compression experiment. Results indicated that the deposition mineral was a low crystallinity carbonate hydroxyapatite with c axis preferential growth and was similar to hydroxyapatite in natural bone. SEM results showed that the sedimentary hydroxyapatite had a gradient distribution in the scaffold. More deposition was observed on the outer pore wall surface than the inner pore wall surface. The exterior pores of the scaffold were partially blocked but the inner pore structure of the scaffold was still interconnected. The porosity of the deposited scaffold was 94.0% and the deposited hydroxyapatite was 13.5% of the total mass after 6 alternate soaking cycles. The compressive strength of the scaffold increased from 0.055 MPa to 0.109 MPa.