We previously reported that the antibiotic elution profiles from calcium phosphate cement (CPC) vary depending on the type and number of impregnated antibiotics. Here, we attempted to determine the underlying factors affecting the elution of vancomycin (VCM) and gentamicin (GM) from CPC. Changes in pore size were investigated after the impregnation of CPC with various antibiotics in either the liquid or powdered state. Porosimetry analysis revealed that the pore sizes of CPC impregnated with powdered antibiotic were larger than those of CPC impregnated with liquid antibiotic. As powdered VCM had poor solubility in the CPC solvent, insoluble VCM particles would block the crystal growth. Scanning electron microscopy observation demonstrated that the solubility of VCM increased after the impregnation of CPC with GM. These findings suggest that the size of CPC pores, which act as passages for antibiotic elution, are affected by the size of undissolved antibiotic particles present within CPC.
Phosphonylation of salicin has been achieved using inorganic disodium diphosphonate (DP) in aqueous solution. The optimum condition for the phosphonylation of salicin with DP is salicin : DP = 0.1 mol/L : 1.0 mol/L, pH 12 and 25°C. 2’, 4’-Diphosphonylsalicin was synthesized with the yield of 50%. We have successfully introduced the two phosphonate groups in one molecule. The reaction mechanism of salicin with DP was discussed.
Lower phosphates, such as phosphites and hypo-phosphites, are known to have a characteristic of particularly strong reducibility. We researched on phosphite compounds and found out that aluminum phosphite had an excellent property. Aluminum phosphite, the product name of ‘APA-100’, was investigated in this study. Since APA-100 has a characteristic of hardened foam material by heating, this material is effective as a flame retardant. As a result of corrosion-resistant evaluation using the copper foil, the control of the corrosion by the effect of APA-100 was found out. Furthermore, we succeeded in the development of the fine particle type of APA-100. The details on aluminum phosphite (APA-100) for various uses were reported.
Biphasic calcium phosphate (BCP) particle consisting of α-tricalcium phosphate and tetracalcium phosphate was synthesized from calcium carbonate and calcium hydrogen phosphate. The Ca/P molar ratio of the product was 1.80. Uni-morphologically controlled BCP particles were synthesized without mixing.
The evaluation of powder properties and the examination based on ISO 13779-3 and JIS T 0330-3 for calcium phosphates as biomaterial were performed. Powder properties were investigated by X-ray diffractometry (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), measurement of specific surface area (SSA), particle size analysis and chemical analysis. Crystalline content and chemical impurities were evaluated by the examination based on ISO 13779-3, and the solubility was evaluated by the examination based on JIS T 0330-3. These results indicated that our products were single phase, and crystalline content and chemical impurities were within the range of specification. Moreover, it was found that hydroxyapatite has different characteristics for particle morphology and SSA according to the difference of synthesis methods. It was comfirmed that the elution amounts of calcium (Ca2+) ion per each specific surface area were different among our products from the examination of solubility. Consequently, these products are expected as raw materials for biomaterials, and the requiered products will be supplied by the application of our technology.
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