Flocea Petruţa, Popa M, Munteanu Fl, Vereştiuc Liliana
Technical University Gh. Asachi Iaşi, School of Chemical Engineering and Environmental Protection, Department of Chemical Engineering.
Rev Med Chir Soc Med Nat Iasi. 2009 Jan-Mar;113(1):286-92.
The paper presents synthesis, swelling properties and in vitro degradation tests of collagen-hydroxyapatite composites, in the order to obtain new bone substitutes. Also, by using a 3D analysis with finite element the tension distribution at bone--synthesised substitute interface and in bone by comparing to bone substitute was determined.
Collagen type I from tendon bovine source, provided from Sigma-Aldrich, has been used for materials synthesis. Composite materials have been obtained by hydroxyapatite (HA) precipitation from its precursors (aqueous solutions of CaCl2 and NaH2PO4), in the presence of NH4OH and process finalising at 37 degrees C. Three types of materials have been prepared: 75% collagen--25% HA(w/w)--Coll75-HA; 50% collagen--50% HA(w/w)--Coll50-HA; 25% collagen--75% HA(w/ w)--Coll25-HA. Swelling properties of the composite materials were evaluated gravimetrically and in vitro degradation in buffered collagenase was studied. The elasticity modulus was calculated from the dependence force versus material's strain. The 3D analysis with finite element at bone--synthesised substitute interface was performed for a right osteosynthesised fracture from femur.
Materials swelling in simulated body fluids revealed higher equilibrium swelling degree for HA-collagen composites with increased content of collagen. Materials are degraded by collagenase, the degradation rate being strongly dependent by composition; a higher content of collagen makes the composites more sensitive to the specific enzyme. SEM data have shown the forming of hydroxyapatite crystals onto collagen fibers. The mechanical characterisation has shown a limited elasticity at an increased value of the applied force for Coll25-HA. Over these forces the plasticity was observed. By using the 3D analysis with finite element at bone--synthesised substitute interface a higher strength was determined in the bone by comparison to bone substitute.
The superior elasticity properties of the synthesised collagen-HA by comparison to physiological biomechanical limits indicate a good behaviour as resistance bone substitute with applications in the extensive bones reconstruction (endoprosthesis revision, bone infections etc.).
本文介绍了胶原 - 羟基磷灰石复合材料的合成、膨胀特性和体外降解测试，以获得新型骨替代物。此外，通过有限元三维分析，确定了骨 - 合成替代物界面处以及与骨替代物相比骨内的张力分布。
使用了西格玛奥德里奇公司提供的牛肌腱来源的I型胶原进行材料合成。通过在氢氧化铵存在下，由其前体（氯化钙和磷酸二氢钠水溶液）沉淀羟基磷灰石（HA）来获得复合材料，并在37℃下完成该过程。制备了三种材料：75%胶原 - 25% HA（重量比） - Coll75 - HA；50%胶原 - 50% HA（重量比） - Coll50 - HA；25%胶原 - 75% HA（重量比） - Coll25 - HA。通过重量法评估复合材料的膨胀特性，并研究其在缓冲胶原酶中的体外降解。根据力与材料应变的关系计算弹性模量。对一例右侧股骨骨合成骨折进行了骨 - 合成替代物界面的有限元三维分析。
材料在模拟体液中的膨胀显示，随着胶原含量增加，HA - 胶原复合材料的平衡膨胀度更高。材料被胶原酶降解，降解速率强烈依赖于组成；较高的胶原含量使复合材料对特定酶更敏感。扫描电子显微镜数据显示羟基磷灰石晶体在胶原纤维上形成。力学表征表明，对于Coll25 - HA，在施加力增加时弹性有限。超过这些力时观察到可塑性。通过骨 - 合成替代物界面的有限元三维分析，与骨替代物相比，确定骨内具有更高的强度。
合成的胶原 - HA与生理生物力学极限相比具有优异的弹性特性，表明其作为承重骨替代物在广泛的骨重建（假体翻修、骨感染等）应用中表现良好。
