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Nanoparticles can be easily transported in vivo and can reach and attack cancer cells. The biodegradable hydroxyapatite(HAp) nanoparticles which strongly inhibited the proliferation of the cancer cell wrapped with degradable copolymer monomethoxy(polyethyleneglycol)-poly (lactide-coglycolide)-monomethoxy (poly-ethyleneglycol) (PELGE). The nanoparticle preparation method is a critical problem for small-sized particles. HAP-loaded nanoparticles(NP) were fabricated by using a double-emulsion system. Orthogonal design was applied to optimize the preparation technology on the basis of the single factor evaluation. The optimal conditions for preparation HAP-loaded nanoparticle was as follows: 20mg/ml was the concentration of PELGE, volume of inner-phase of HAp was 0.5ml(C=12.5mg/ml), the ratio of DCM/acetone was 3/2 and the concentration of PluronicÒ F68 (Poloxamer 188 NF) was 3%. The entrapment efficiency was >88% and particle size less than 500nm. The nanoparticles, as detected by transmission electron microscopy (TEM), have a smooth and spherical surface. The HAP could be loaded into PELGE copolymers. In this study , the HAP nanoparticle-polymer delivery system was established using PELGE polymers as wraping material.

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In vitro study of biomaterials in SBF is a very important approach to understand the bioresponse of implants in vivo. This study aimed at exploring the effect of dynamic SBF flowing at normal physiological rate of body fluid in skeletal muscle upon the formation of bone-like apatite on the surface of pores and dense HA/TCP calcium ceramics. Results demonstrated that in normal physiological rate, the surface of dense ceramic can not be found the bone-like apatite. Results showed that bone-like apatite formation could only be found in the internal pores of the materials when SBF flowing at physiological rate was coordinated with that of in vivo implantation of calcium phosphate ceramics: most of the ectopic bone formation was detected inside the pore of the porous calcium phosphate ceramics and no new bone was found on surface of dense ceramics. This result demonstrated that dynamic model used in this study was better than usually static immersion model in mimicking the physiological condition of in vivo formation of bone-like apatite. Dynamic SBF method is very useful for understanding the in vivo formation of bone-like apatite and the mechanism of ectopic bone formation of calcium phosphate ceramics.