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The present study was designed to investigate the extent of osteoconductive property of a mechanical mixture of octacalcium phosphate (OCP) and amorphous calcium phosphate (ACP). OCP was mixed with ACP in granules that had a diameter of 300 and 500 μm, respectively, and at 25, 50, or 75 wt %. The physicochemical characteristics and the osteoconductive properties of the mixtures were compared with OCP alone or ACP alone through implantation into rat critical-sized calvaria defects for up to 12 weeks and simulated body fluid (SBF) immersion for 2 weeks. The mixtures of OCP and ACP, in particular the OCP 25 wt % and ACP 75 wt % (O25A75), had higher radiopacity compared to ACP and OCP alone. O25A75 induced greater enhancement of bone regeneration than ACP alone at 8 weeks and that than OCP alone at 12 weeks. X-ray diffraction and Fourier transform infrared (FTIR) analyses of the retrieved mixtures showed that ACP, OCP, and O25A75 tended to convert to hydroxyapatite (HA) after the implantation, while the structure of OCP remains without complete conversion after SBF immersion. Analyses by FTIR curve fitting of the solids and the degree of supersaturation of the SBF supported the observation that the existence of ACP enhances the kinetics of the conversion. Scanning electron microscopy found that the surface of O25A75 had distinct characteristics with OCP and ACP after SBF immersion. The results suggest that the extent of the osteoconduction of OCP could be controlled by the copresence of ACP most probably through the prevailing dissolution-precipitation of the surface of ACP crystals to form HA.

The gelatin (Gel) powders, derived from acidic and basic extractions of porcine dermis (referred to as AE and BE), were processed for the porous sponge preparation. The disks, which were less than or greater than 500 μm in diameter [small (S) and large (L) pores, respectively] in both extractions and had an interconnected structure respectively, were implanted in critical-sized defects (CSD) of rat calvaria for 4 and 8 weeks to analyze the bone repair capability. Only the AE-S disk induced bone formation (over 60%) histomorphometrically in the CSD after 8 weeks, although the collagen orientation of the regenerated bone was still immature. Osteoblastic cell culture until 14 days did not substantiate marked superiority of AE-S disk regarding the proliferation and the differentiation, although the initial attachment was enhanced on AE-S disk than BE-L disk. The results provide the findings that a Gel sponge with a specific porous structure is capable of inducing orthotopic bone formation in vivo environment.

This research focuses on the extraction and characterisation of chitin and chitosan from fungal biomass, Termitomyces titanicus, by immersing it in a solution of sodium hydroxide, followed by deacetylation in a basic medium using the full two-level factorial design (2 2) to obtain chitosan as a residual. The obtained chitosan was characterised by basic conductimetric titration and viscometry to determine the degree of deacetylation and the average molecular weight, respectively. The extraction of chitin was carried out under the following operating conditions: particle size less than 2.5 mm; hydrolysis time of 120 min; concentration 3 M of the NaOH solution; and temperature of 100 °C. The extraction yield of chitin was 38.04%, and the degree of deacetylation of chitosan was 69.50%, an intrinsic viscosity of 0.6822 dL/g, and a viscosimetric average molecular weight of 985.88 kDa. This research therefore shows that fungus specie called T. titanicus can serve as an alternative chitin and chitosan source. In addition, the mathematical model established for deacetylation degree that, based upon the extra process time, it would be possible to increase the purity of chitosan.

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