Apatite-collagen complex as a possible bone substitute

在pH为8.50的β-甘油磷酸钙溶液中制备了一种新的磷灰石-胶原复合体。在一种制剂中，重组的I型胶原在碱性磷酸酶存在的情况下，通过使用交联剂亚硝酸二甲酯与磷高磷蛋白进行交联化。在每日更新的β-甘油磷酸钙溶液中浸泡两周后，磷灰石沉积在胶原纤维上。这样制备的磷灰石-胶原复合体的磷灰石重量大约是改性胶原的两倍。扫描电子显微镜下可见胶原纤维上有密集的针状晶体沉淀。然而，在复合体的某些部分，也观察到点状沉淀。X-射线衍射和红外光谱分析表明，在胶原纤维上析出的磷灰石在结晶度和碳酸盐含量两个方面与骨矿物非常相似。犬牙…修复后作为骨替代物植入1个月在进一步提取之前，发现该复合体被吸收，没有实质性的异物反应。植入复合体的部位充满了新形成的骨。在第二种制备方法中，将沉积有磷灰石的胶原片置于磷灰石水泥中，在600 Mpa的等静压下，将其浸泡在37ﾟC的蒸馏水中7天，完全转化为磷灰石。对得到的片状胶原层状磷灰石块进行了四点弯曲试验，加载方向垂直于块内片材。载荷被绘制为块状试件纵向位移的函数。对有和没有胶原片的块状试件获得的数据进行比较表明，胶原片的存在不能增加弯曲强度，但增加了在试件上所做的功。未处理的胶原片也尝试在磷灰石中进行层压。然而，几乎不可能准备压实的积木。这一发现表明，在胶原片上预沉积磷灰石晶体是胶原与磷灰石成功结合的关键步骤，说明沉积在胶原片上的磷灰石在胶原片的固化过程中起到了种子晶体的作用。较少

A new apatite-collagen complex was prepared in calcium beta-glycerophosphate solutions at pH 8.50. In one preparation, reconstituted type I collagen was cross-linked with phosvitin in the presence of alkaline phosphatase by the use of cross-linking agent of dimethyl subrimidate. After two weeks of immersion in daily-renewed solution of calcium beta-glycerophosphate, apatite deposited on the collagen fibrils. The apatitte-collagen complex thus prepared contained apatite approximately two times the modified collagen in weight. When viewed under a scanning electron microscope, needle-like crystals precipitated densely on the collagen fibrils. In some portion of the complex, however, dotlike precipitate was observed as well. X-ray diffraction and IR analyses of the complex suggested that apatite precipitated on the collagen fibrils was very similar to bone mineral in two aspects, crystallinity and carbonate content. When implanted for one month as a bone substitute in dog jaw after teeth w … More ere extracted, the complex was found resorbed without no substantial foreign body response. The site where the complex was implanted was filled with newly formed bone. This finding may suggest that the apatite-collagen, -complex prepared here is biodegrable and osteogeneiic as well.In the second preparation, atelocollagen sheets (MEIPAK) with apatite deposited on were laminated in apatite cement consisting of an equisolar mixture of Te-CP and DCPD under isostatic pressure of 600 MPa, which was later immersed in distilled water at 37ﾟC for 7 days to completely transform the sement portion into apatite. The sheet-collagen laminated apatite blocks thus obtained were subjected to four points bending test with a loading direction perpendicular to the sheets inside the block. The load was plotted as a function of longitudinal displacement of the block specimen. Comparison of data obtained from the block specimens with and without the collagen sheets showed that presence of the collagen sheet failed to increase the bending strength but increased the work done on the specimen. Non-treated collagen sheet was also tried to laminate in apatite. However, it was practically impossible to prepare compacted blocks. This finding suggests that predeposition of apatite crystals on collagen sheet is a key step to successfully combine collagen and apatite, indicating that apatite deposited on collagen sheet acts as seed crystal for the sement setting process. Less