【作者】 向鸿照；

【导师】 李玉宝；

【作者基本信息】 四川大学 ， 生物无机化学， 2007， 博士

【摘要】 骨是自然界中一种复杂的生物材料,它不仅具有良好的力学性能,而且是人体中钙磷等离子的储存场所,它随着人体的生长发育逐渐的形成完善。当骨组织因为创伤、感染、肿瘤及发育异常等原因实施手术剔除病变骨组织后,会造成大块骨缺损,这时仅仅依靠骨自身的修复能力已经无法愈合,必须进行骨移植手术,将合适的骨材料填充缺损部位,以便于新骨生长。移植骨的来源有自体骨、异体骨和人工骨材料。自体骨移植和异体骨移植存在供体有限和免疫排斥等诸多问题。因而发展以生物材料为基础的人工骨材料是治疗骨缺损的重要手段。理想的骨修复材料,应当具有优良的生物相容性和生物活性,与天然骨相匹配的良好的机械力学性能。自然骨主要是由羟基磷灰石和胶原高分子组成,羟基磷灰石均匀分布在胶原中。自然骨为设计骨替代材料提供了非常重要的启发和思路,促进了骨替代材料的研究和发展。羟基磷灰石(HA)是骨组织的主要无机成分,生物相容性好,具有较高的生物活性,能够与骨组织形成化学键合,但其脆性和不易加工性也限制了其应用。壳聚糖(CS)是一种天然的生物可降解多糖,其降解产物为氨基葡萄糖,具有一定的碱性,对人体组织无毒、无害。将其与纳米羟基磷灰石(n-HA)复合,不仅可以克服羟基磷灰石块状陶瓷的脆性,而且其降解又可为细胞及组织的长入提供空间,从而促进新骨的生成,并使植入物与骨组织间结合更为牢固。聚酰胺(PA)是一类优良的医用高分子材料,具有较高的韧性和强度,但缺乏生物活性,在临床上有广泛而长期的应用。已用来和羟基磷灰石复合制备新型生物活性骨修复材料。如果能综合上述三者的性能,扬长避短,优势互补,可望得到一种理想的骨修复替代材料。我们通过溶液共混法制备了n-HA/PA66/CS骨修复材料,并对其性质进行了检测。实验结果表明,复合材料中n-HA,PA66和CS三相间有良好的相容性,没有相分离现象发生;复合材料中各相间存在较强的相互作用,由此赋予材料良好的力学性能。当复合材料中n-HA/PA66/CS含量为40/45/15(wt%)时,其抗压强度最高,达到70MPa左右。体外模拟体液(SBF)浸泡试验结果表明,在复合材料表面有类骨磷灰石层形成,说明n-HA/PA66/CS复合材料具有较高的生物活性。通过粒子沥滤法制备了n-HA/PA66/CS多孔支架材料。结果显示,该多孔材料中兼具大孔和微孔,大孔壁上又富含微孔,孔与孔之间连通性良好。当平均空隙率为60.8%时,其抗压强度仍可达7.2MPa左右,可基本满足骨组织工程对细胞支架材料的要求。对n-HA/PA66/CS复合材料进行的多项生物学评价试验显示,复合材料小鼠急性全身毒性试验中未见毒性症状,表明复合材料无毒性;皮内刺激试验显示复合材料无刺激性作用;细胞毒性试验显示复合材料无细胞毒性。动物植入试验中,肌肉植入早期有轻度炎症反应,后期形成薄层纤维包膜,炎症反应消失;骨内植入后材料与骨组织结合紧密,材料/骨组织之间无纤维薄层,表现出复合材料具有良好的组织相容性和骨结合性能。从生物学评价结果可以看出复合材料具有良好的生物相容性,是一类具有发展前景的新型骨组织修复和替代材料。更多还原

【Abstract】 Bone is one of the most complicated composite in the nature. Bone, not only provides mechanical support but also elegantly serves as a reservoir for minerals, particularly calcium and phosphate. It is a good example of a dynamic tissue, since it has a unique capability of self-regenerating or self-remodeling to a certain extent throughout the life. However, many circumstances call for bone grafting owing to bone defects either from traumatic or from non-traumatic destruction. In the case of severe defects and loss of volume, bone cann’t heal by itself and grafting is required to restore function without damaging living tissues. There are multiple methods available for the treatment of bone defects, which include the traditional methods of autografting , allografting and synthetic bone. Although autografting and allografting are clinically considered as good therapies, they have limitations. For example, supply of autograft is limited and there is a possibility of pathogen transfer from allograft. Accordingly, there is a great need for the use of synthetic bone grafts. Nowadays, numerous synthetic bone graft materials, both single- and multi-phases, are available which are capable of alleviating some of the practical complications associated with the autogenous or allogeneic bones.The bone mineral is mainly composed of hydroxyapatite(HA) and the bone protein is mainly composed of collagen. Ideal bone-repair materials should be of good biocompatibility and high bioactivity. Besides, their mechanical properties should be equivalent to natural bone.HA is the main inorganic composition of bone tissue and is of good biocompatibility and high bioactivity, which makes it be able to chemically bond to bone tissue. However, the brittleness and hard machining limit its extensive clinical use. Chitosan(CS) is a natural biodegradable polymer. Its degradation product is alkalescent and is not harm and toxic to human body or tissue. Compounding chitosan with nano hydroxyapatite(n-HA) could overcome the brittleness of HA ceramics, and that the degradation of chitosan also makes space for the ingrowth of cells and tissuesPolyamide66 is used as matrix and can provide a good mechanical and biocompatible property. It is well known that polymers have better toughness, but it lacks of bioactivity. So, if combining the properties of the three materials to carry their good properties forward and get rid of their shortcomings, it will be hopeful to obtain a good bone substitute material. Here, PA66 acts as a structural framework in which tiny crystals of n-HA are embedded to strengthen the bone.In this paper, n-HA/PA66/CS composite is prepared with co-solution method. The testing results show that HA in the composite is poorly crystalline carbonated nano-crystals and dispersed uniformly in the CS/PA66organic phase. The three phases in n-HA/PA66/CS composite have an excellent miscibility and no phase-separation occurs in the blend. Stronger interactions exists among the three phases of n-HA, PA66 and CS, which endows the materials with excellent mechanical strength. When the weight content of n-HA/PA66/CS is 40/45/15 (wt%), the compressive strength of the composite is best, reaching to 70 MPa. In vitro test shows that bone-like apatite deposits onto the surface of the composite, indicating that the composite has good bioactivity.We use polyamide66 as scaffold, blend with n-HA and chitosan by porogen-leaching method in the paper, hoping to acquire a scaffold with good pore size, porosity and mechanical property. Results show that macro-pores and micro-pores coexist in the scaffold, and abundant micro-pores also exist on the wall of macro-pores, and these pores are highly interconnected. When the average pore size is 60.8%, the compressive strength of the scaffold can still reach 7.2 MPa, and can satisfy the demand of tissue engineering when as a cell scaffold.The biological and in vivo tests for n-HA/PA66/CS compostie indicated that, there were no toxic sysptoms showing up after the extract liquid of the composite was injected into the body of mice ; no irritative reactions were found in undermic stimulation test and also no derma allergy was observed. Intramuscular implantation showed that , inflammation reaction was observed in the early period but later a thin fibrin membrane still existed amound the implant and the inflammation reaction disappeared. When compostie was implanted in the bone , the compostie boned to bone tightly and no fibrin tissues were presented between material ans bone tissue, demomstrating cxcellent tissue compatibility and bone-bonding property. Therefore, n-HA/PA66 /CS composite can be figured to be biocompatible and has a potential to be used for new bone repair and substitute materials.更多还原