In vitro formation of bone-like apatite on the surface of solution-cast poorly crystallised hydroxyapatite/chitin composite

Abstract

Poorly crystallized hydroxyapatite (HA) particles were incorporated into chitin using the solution casting technique to produce a composite for potential medical applications. The optimised manufacturing condition resulted in ceramic particles being dispersed homogeneously in the composite. Composite plates having 10-60 wt% of the bioceramic were successfully produced. Plates of chitin and its composite were subsequently treated in a 5M NaOH solution at 60°C for 20 hours. In vitro mineralisation experiments were performed on as-cast and alkaline treated plates using simulated body fluid (SBF). It was shown that the poorly crystallized HA particles rendered the composite bioactive and improved the ability to induce the formation of bone-like apatite on material surfaces. An incubation temperature higher than 36.5°C accelerated the nucleation of bone-like apatite on the composite surface because of the dissolution of D-glucopyranose residues available which led to the increase in hydroxyl concentration in the vicinity of the surface. The alkaline treatment introduced more D-glucopyranose in chitin and hence significantly improved the in vitro nucleation of bone-like apatite on surfaces of chitin and its composite when they were immersed in SBF.