湿法合成纳米缺钙磷灰石的实验研究

目的:合成与人体骨磷灰石成分接近的纳米缺钙磷灰石.方法:将(NH4)2HPO4和Ca(NO3)2按照2:1的比例混合、振荡合成、陈化24 h后,清洗、离心、烘干.采用X线衍射、透射电镜、红外光谱及能谱分析等实验手段,对合成的磷灰石进行观察与评价.结果:(NH4)2HPO4和Ca(NO3)2在震荡条件下进行化学湿法合成,可制备出长约40～60 nm,宽约15～22 nm左右的缺钙磷灰石颗粒.,这种颗粒结构与通常的针状羟基磷灰石结构相比,更接近于人体骨磷灰石(长约50～64 nm,宽度为24～30 nm);该颗粒具有与骨磷灰石接近的钙磷比、相似的纳米尺寸、较低的结晶度,还含有一定量的碳元素.其合成过程简便易行,原料来源普通、经济.因为与人体骨磷灰石有着诸多的相似之处,经过今后的生物学实验,将有望成为生物活性更高的体内植入材料.结论:利用湿法合成纳米缺钙磷灰石简便有效、成分稳定、晶粒形貌受环境温度影响小,在纳米尺寸和成分上与骨磷灰石高度相似.

Implanting hydroxyapatite-coated porous titanium with bone morphogenetic protein-2 and hyaluronic acid into distal femoral metaphysis of rabbits

Objective： To assess the osseointegration capability of hydroxyapatite-coated porous titanium with bone morphogenetic protein-2 （BMP-2） and hyaluronic acid to repair defects in the distal femur metaphysis in rabbits. Methods： Porous titanium implants were made by sintering titanium powder at high temperature, which were coated with hydroxyapatite by alkali and heat treatment and with BMP-2 combined with bone regeneration materials. And hyaluronic acid was further used as delivery system to prolong the effect of BMP-2. The implants were inserted into the metaphysis of the distal femur of rabbits. The animals were killed at 6, 12 and 24 weeks to accomplish histological and biomechanical analyses. Results： According to the result of histological analysis, the osseointegration in BMP-2 group was better than that of the HA-coated porous titanium group. In push-out test, all the samples had bigger shear stress as time passed by. There was statistical difference between the two groups in 6 and 12 weeks but not in 24 weeks. Conclusion： Hydroxyapatite-coated porous titanium with BMP-2 and hyaluronic acid has a good effect in repairing defects of distal fumur in rabbits, which is a fine biotechnology for future clinical application.

Effect of nano-hydroxyapatite/collagen composite and bone morphogenetic protein-2 on lumbar intertransverse fusion in rabbits

Objective: To investigate the effect of nano hydroxyapatite/collagen (nHA/collagen) composite as a graft extender and enhancer when combined with recombinant human bone morphogenetic protein 2 (rhBMP 2) on lumbar intertransverse fusion in rabbits. Methods: Sixty four adult female New Zealand white rabbits, aged 1 year and weighing 3.5 4.5 kg, underwent similar posterolateral intertransverse process arthrodesis and were randomly divided into 4 groups based on different grafts: autogenous cancellous bone alone (ACB group), nHA/collagen alone (HAC group), half autogenous cancellous bone and half nHA/collagen (ACB+HAC group) and nHA/collagen combined with rhBMP 2 (HAC+BMP group). The fusion masses were analyzed by manual palpation, radiography, biomechanical testing and histological examination. Results: Fusion was observed in 4 cases in the 6th week and in 5 cases in the 10th week after surgery in ACB group. No case showed fusion in HAC group. In ACB+HAC group, there was fusion in 3 cases in the 6th week and in 4 cases in the 10th week after surgery. In HAC+BMP group, fusion in 1 case was found in the 4th week, in 5 cases in the 6th week and in 6 cases in the 10th week after surgery. It suggested that ACB, ACB+HAC and HAC+BMP groups showed similar fusion ratio and mechanical strength in the 6th and 10th week after surgery. According to the microstructure analysis of the samples, nHA/collagen had no negative effect when implanted together with ilium autograft. In HAC+BMP group, new bone like tissue was observed in the 2nd week postoperatively, and nearly all of the implanted composites were replaced by mature bone matrix and new bones in 10th week postoperatively. Conclusions: The nHA/collagen, especially combined with rhBMP 2, is a promising bone substitute, for it has quick biodegradation, fine bone bending ability, and high osteoconductivity on posterolateral spinal fusion in rabbits.