明胶联合壳聚糖纤维对磷酸钙骨水泥力学性能的影响

doi:10.3969/j.issn.2095-4344.2013.03.005

摘要/Abstract

摘要：

背景：已有多种纤维被用于提高磷酸钙骨水泥的强度及抗断裂性能。
目的：了解明胶联合壳聚糖纤维对磷酸钙骨水泥力学性能的影响，寻找较为合适的配比。
方法：采用2×4析因设计，将质量比为0(蒸馏水)，5%的明胶，体积比为0，10%，30%和50%的壳聚糖纤维分别混入磷酸钙骨水泥，检测复合物的抗弯曲强度，扫描电子显微镜观察各组试样断口形态并进行电子能谱分析。
结果与结论：各明胶组间抗弯强度差异有非常显著性意义(P < 0.001)；各体积比纤维间抗弯强度差异有非常显著性意义(P < 0.001)，其中5%明胶和30%壳聚糖纤维构成的复合物抗弯曲强度最大，达 12.31 MPa。以蒸馏水为液相的磷酸钙骨水泥固化后，表面可见不规则颗粒，平均微孔直径小于5 μm，添加明胶后颗粒似乎黏在一起，微孔直径与前者相似，但是数目少于前者。磷酸钙骨水泥-5%明胶-30%纤维复合物的断口扫描可见拔出纤维的表面黏附有大量颗粒，磷酸钙骨水泥-蒸馏水-30%纤维复合物拔出纤维表面的颗粒明显减少。表明明胶与壳聚糖纤维可提高磷酸钙骨水泥的抗弯曲强度，5%明胶和30%壳聚糖纤维为这种增强模式较为合适的比例。

关键词: 生物材料, 组织工程骨材料, 壳聚糖, 纤维, 明胶, 磷酸钙骨水泥, 抗弯强度, 生物力学, 其他基金, 生物材料图片文章

Abstract:

BACKGROUND: A few of fibers have been used to reinforce the strength and fracture resistance of calcium phosphate cement.
OBJECTIVE: To investigate the influence of gelatin combined with chitosan fiber on the mechanical properties of calcium phosphate cement and to look for a more appropriate ratio.
METHODS: Comparisons and to look of chitosan fibers at volume fractions of 0, 10%, 30% and 50% together with distilled water or gelatin at mass fraction of 5% respectively in their effects on flexural strength of cement were performed. 2×4 factorial design was adopted. Flexural strength of cement composite fractures was detected, and fractured surface morphology was observed by scanning electron microscope. Energy dispersion analysis was also performed on particles of composites.
RESULTS AND CONCLUSION: A significant difference was found between the flexural strength of different gelatin groups and between the flexural strength of different volume fraction groups (P < 0.001). The maximal flexural strength was obtained when the calcium phosphate cement was reinforced with fiber at volume fraction of 30% and gelatin at mass fraction of 5%, which was 12.31 MPa. With distilled water as the liquid phase, there were irregular particles (mean pore diameter < 5 μm) on the surface of the solidified calcium phosphate cement. After gelatin adding, gelatin and particles seemed to stick together, and the mean pore diameter was similar to the above-mentioned, but the number was less than the former. A great amount of particles were seen at the fractured surface of calcium phosphate cement reinforced with fiber at volume fraction of 30% and gelatin at mass fraction of 5%, and the number of particles was decreased significantly at the fractured surface of calcium phosphate cement reinforced with distilled water and fiber at volume fraction of 30%. The mechanical property of calcium phosphate cement could be enhanced by using gelatin and chitosan fiber as two reinforcement agents, and gelatin at the mass fraction of 5% and chitosan fiber at the volume fraction of 30% might be a better ratio for this reinforcement mode.

Key words: biomaterials, tissue-engineered bone materials, chitosan, fibers, gelatin, calcium phosphate cement, flexural strength, biomechanics, other grants-supported paper, biomaterial photographs-containing paper

中图分类号:

R318

潘朝晖，赵玉祥，张俊国，王大伟. 明胶联合壳聚糖纤维对磷酸钙骨水泥力学性能的影响[J]. 中国组织工程研究, 2013, 17(3): 407-411.

Pan Zhao-hui, Zhao Yu-xiang, Zhang Jun-guo, Wang Da-wei. Gelatin combined with chitosan fiber affects the mechanical properties of calcium phosphate cement[J]. Chinese Journal of Tissue Engineering Research, 2013, 17(3): 407-411.

图/表（结果） 2

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引言

材料方法

讨论

从断裂力学的角度看，纤维增强能减小纹尖端的应力集中现象，提高抗裂纹扩展的能力。添加纤维是提高磷酸钙骨水泥固化体强度的一种较为有效的方法^[11-15]。复合材料的增强系统决定其增强机制，明胶、壳聚糖纤维和磷酸钙骨水泥复合材料的界面结合强度与复合材料的微结构、各材料间化学结合力及颗粒与聚合物间的机械绞锁等因素有关。

3.1 微结构的改变在磷酸钙骨水泥这种脆性大的基质中，基质承担着大部分载荷。基质除了将纤维聚在一起，还有一个重要的功能就是传递载荷。当裂纹扩展到界面时，由于界面间有适当的结合力，裂纹会沿着纤维发生偏离，从而有效延长裂缝在整个基质中扩展的时间，只有提高外加应力才能使裂纹继续扩展，裂纹因此受到阻碍，或被钉扎而抑制进一步地延伸或向另一个方向转移消耗更多的能量，达到增强的作用^[11]。复合材料要想达到预期的特性，所受载荷必须通过界面从基质有效传递到纤维^[15]。这就要求界面必须够大，从而纤维和基质间有较强的黏附力。

首先基质材料必须“湿化”纤维，“湿化”纤维就可以增加界面的表面积。扫描电子显微镜观察显示，体积比为10%或30%时纤维可以较好分散并被磷酸钙骨水泥“湿化”。其次基质的孔隙率要小。磷酸钙骨水泥水合终产物为羟基磷灰石，如果仅用水作液相，未反应的水从水泥中游离以及掺入的空气均可产生孔隙，所以强度较低。添加明胶后可在磷酸钙骨水泥和明胶间形成基质界面，填充孔隙，减小气孔对裂纹的影响，提高强度。尽管纤维加入会带入空气，降低复合物强度，但是在纤维体积较少的情况下，经过手工挤捏，大部分空气会自行排出；同时随着纤维体积比增加，参与消除应力集中、阻止裂纹扩展的纤维增多，强度会进一步提高。但当纤维体积比增加到50%后，纤维分散较为困难，掺入的空气骤然增多，强度随之降低。

3.2 磷酸钙骨水泥颗粒和聚合物间的化学结合明胶主链上高浓度的羧基及相当多的氨基可与钙、磷等矿物离子作用，促进磷酸钙骨水泥固化反应，提高其力学强度^[17]。明胶主链上的羧基还能和壳聚糖以氢键结合，加入明胶后，壳聚糖纤维的抗张强度也会提高，证明了两者之间的相互作用^[19-20]。但如果以高浓度的明胶为骨水泥的液相，又会阻止水泥粉末均匀扩散，使磷酸钙骨水泥丧失可塑性及黏结的性能。分析其原因可能仍然与明胶提供的活性基团过多有关，这些基团与其他活性基团相互作用，影响水泥的聚合。

3.3 磷酸钙骨水泥颗粒和聚合物之间的机械绞锁扫描电子显微镜及能谱分析显示添加质量比5%的明胶和10%及30%体积比纤维的复合物断口有大量的磷酸钙骨水泥基质黏附于拔出纤维的表面，提示纤维和水泥颗粒间存在较高的结合能。这种不规则颗粒可以和周围颗粒形成绞锁，也是其增强的原因之一。

总之，明胶和壳聚糖纤维可作为增强剂以提高磷酸钙骨水泥的抗弯强度，质量比5%明胶和体积比30%壳聚糖纤维为这种增强模式较为合适的比例，其增强机制和微结构变化、化学结合及机械绞锁有关。

基金资助：军队“十二五”面上课题资助项目(CWS11J245)。
作者贡献：设计和实施为第一、三、四作者，第二作者进行评估，均受过相关培训。
利益冲突：课题未涉及任何厂家及相关雇主或其他经济组织直接或间接的经济或利益的赞助。
作者声明：文章为原创作品，数据准确，内容不涉及泄密，无一稿两投，无抄袭，无内容剽窃，无作者署名争议，无与他人课题以及专利技术的争执，内容真实，文责自负。