Fabrication and Biocompatibility of an Antimicrobial Composite Membrane with an Asymmetric Porous Structure

A composite slurry from silver ion-substituted nano-hydroxyapatite, titania nano-particles and polyamide 66 (Ag-nHA/TiO₂/PA66) was prepared and used to fabricate a novel antimicrobial membrane with a gradient porous structure for guided bone regeneration (GBR). Subsequently, assays were performed to determine the cytocompatibility, as well as the bone biocompatibility of the prepared membranes. To investigate the cytocompatibility of the Ag-nHA/TiO₂/PA66 membrane, in vitro studies were done with osteoblast-like cells (MG63) and the viability, alkaline phosphatase activity (ALP) and morphology of cells cultured on the membrane were determined. The bone biocompatibility of the membranes was finally assessed in animal experiments, in which nano-hydroxyapatite/polyamide 66 (nHA/PA66) and pure polyamide 66 (PA66) membranes were compared. The in vitro cell-culture experiments showed that Ag-nHA/TiO₂/PA66 antimicrobial membrane evoked good cell affinity and cytocompatibility. The in vivo study showed that Ag-nHA/TiO₂/PA66 asymmetric porous barrier membrane resulted in complete closure of 5-mm bone defects as created in the skull of rats after 8 weeks of implantation. In conclusion, the Ag-nHA/TiO₂/PA66 membrane has the potential to be applied in GBR, especially in infected tissue or areas with high bacteria concentration.     

In Vitro and In Vivo Evaluation of a nHA/PA66 Composite Membrane for Guided Bone Regeneration

A nano-hydroxyapatite/polyamide 66 (nHA/PA66) composite with good bioactivity and osteoconductivity is employed to develop a novel porous membrane with an asymmetric structure. In order to investigate the biocompatibility and the effect on guided bone regeneration (GBR) of nHA/PA66 porous membrane, the proliferation, viability, morphology and alkaline phosphatase activity (ALP) of the osteoblast-like cell line (MG63) cultured on the membrane were studied in vitro. In vivo biocompatibility and osteogenesis of the fabricated membrane were assessed by comparing guiding rats calvarial bone defects regeneration with "gold standard" GBR material, expanded polytetrafluoroethylene (e-PTFE) membrane. In vitro experiments showed that the nHA/PA66 composite membrane had good cell affinity and cytocompatibility, in favor of cell proliferation. The in vivo study showed that the nHA/PA66 asymmetric porous membrane had a good GBR effect. All the results indicate that the asymmetric porous nHA/PA66 composite GBR membrane with good biocompatibility, high bioactivity and osteoconductivity exhibits good GBR effect and has a potential to be applied in GBR fields, especially in dental tissue regeneration.     

Effect of biological/physical stimulation on guided bone regeneration through asymmetrically porous membrane

Asymmetrically porous polycaprolactone (PCL)/Pluronic F127 guided bone regeneration (GBR) membranes were fabricated. The top surface of the membrane had nanosize pores (～10 nm) which can effectively prevent invasion by fibrous connective tissue but permeate nutrients, whereas the bottom surface had microsize pores (～200 μm) which can enhance the adhesiveness with bone tissue. Ultrasound was applied to a bone morphogenetic protein (BMP-2)-immobilized PCL/F127 GBR membrane to investigate the feasibility of using dual biological (BMP-2) and physical (ultrasound) stimulation for enhancing bone regeneration through the membrane. In an animal study using SD rats (cranial defect model), the bone regeneration behavior that occurred when using BMP-2-loaded GBR membranes with ultrasound treatment (GBR/BMP-2/US) was much faster than when the same GBR membrane was used without the ultrasound treatment (GBR/BMP-2), as well as when GBR membranes were used without stimulations (GBR). The enhanced bone regeneration of the GBR/BMP-2/US group can be interpreted as resulting from the synergistic or additive effect of the asymmetrically porous PCL/F127 membrane with unique properties (selective permeability, hydrophilicity, and osteoconductivity) and the stimulatory effects of BMP-2 and ultrasound (osteoinductivity). The asymmetrically porous GBR membrane with dual BMP-2 and ultrasound stimulation may be promising for the clinical treatment of delayed and insufficient bone healing.     

Reinforced nanohydroxyapatite/polyamide66 scaffolds by chitosan coating for bone tissue engineering

High porosity of scaffold is always accompanied by poor mechanical property; the aim of this study was to enhance the strength and modulus of the highly porous scaffold of nanohydroxyapatite/polyamide66 (n-HA/PA66) by coating chitosan (CS) and to investigate the effect of CS content on the scaffold physical properties and cytological properties. The results show that CS coating can reinforce the scaffold effectively. The compress modulus and strength of the CS coated n-HA/PA66 scaffolds are improved to 32.71 and 2.38 MPa, respectively, being about six times and five times of those of the uncoated scaffolds. Meanwhile, the scaffolds still exhibit a highly interconnected porous structure and the porosity is approximate about 78%, slightly lower than the value (84%) of uncoated scaffold. The cytological properties of scaffolds were also studied in vitro by cocultured with osteoblast-like MG63 cells. The cytological experiments demonstrate that the reinforced scaffolds display favorable cytocompatibility and have no significant difference with the uncoated n-HA/PA66 scaffolds. The CS reinforced n-HA/PA66 scaffolds can meet the basic mechanical requirement of bone tissue engineering scaffold, presenting a potential for biomedical application in bone reconstruction and repair.     

Synthesis and characterization of nano-hydroxyapatite/polyamide 66 biocomposites reinforced with multi-walled carbon nanotubes

In this work, we investigate the enhanced mechanical properties of nano-hydroxyapatite/polyamide 66 (nHA/PA66) composites reinforced with multi-walled carbon nanotubes (MWCNTs) by means of the blending method. The MWCNTs–nHA/PA66 composites were characterized by various techniques, and the obtained results indicated that the MWCNTs were evenly distributed in the composite and that good interfacial bonding was formed between MWCNTs and PA66. The addition of MWCNTs improved the crystallinity of PA66, while it had little or no effect either on the composition or on the crystal structure of the composites. Moreover, the addition of MWCNTs in nHA/PA66 significantly improved the mechanical strength, and the tensile and compressive strengths attained maximum values of 90.3 and 126.8 MPa, respectively, with the addition of 0.1 wt% MWCNTs, whereas the bending strength attained a maximum value of 105.5 MPa with the addition of 0.05 wt% MWCNTs. Finally, L929 cells co-cultured with the MWCNTs-nHA/PA66 composite exhibited comparatively uninhibited cell growth, indicating that the addition of MWCNTs had negligible effect on the cytocompatibility of the original nHA/PA66 composite.     

n-HA/PA66复合生物活性融合器在颈椎病前路减压融合术中的初步应用研究

分析52例颈椎病行前路减压、n-HA/PA66复合生物活性融合器植骨、钛钉板系统内固定颈椎前路重建手术患者的临床资料,探讨自行研制的纳米羟基磷灰石/聚酰胺66(n-HA/PA66)复合生物活性融合器在颈椎病前路减压固定融合手术中的初步临床疗效。所有术后均获得6～25个月(平均13个月)的随访。患者术前症状均得到改善,JOA评分术前平均为10.4分,术后为15.7分。n-HA/PA66复合生物活性融合器于术后3～6个月骨性融合。颈椎生理曲度、椎间高度、颈椎稳定性均维持良好。无融合器下沉、塌陷、移位发生,无感染、内固定物松动、脱落、断裂等并发症。n-HA/PA66复合生物活性融合器能有效重建和维持颈椎体的结构和高度,可能是一种理想的颈椎植骨替代材料。     

Biocompatibility and osteogenesis of biomimetic nano-hydroxyapatite/polyamide composite scaffolds for bone tissue engineering

In this study, we prepared nano-hydroxyapatite/polyamide (n-HA/PA) composite scaffolds utilizing thermally induced phase inversion processing technique. The macrostructure and morphology as well as mechanical strength of the scaffolds were characterized. Mesenchymal stem cells (MSCs) derived from bone marrow of neonatal rabbits were cultured, expanded and seeded on n-HA/PA scaffolds. The MSC/scaffold constructs were cultured for up to 7 days and the adhesion, proliferation and differentiation of MSCs into osteoblastic phenotype were determined using MTT assay, alkaline phosphatase (ALP) activity and collagen type I (COL I) immunohistochemical staining and scanning electronic microscopy (SEM). The results confirm that n-HA/PA scaffolds are biocompatible and have no negative effects on the MSCs in vitro. To investigate the in vivo biocompatibility and osteogenesis of the composite scaffolds, both pure n-HA/PA scaffolds and MSC/scaffold constructs were implanted in rabbit mandibles and studied histologically and microradiographically. The results show that n-HA/PA composite scaffolds exhibit good biocompatibility and extensive osteoconductivity with host bone. Moreover, the introduction of MSCs to the scaffolds dramatically enhanced the efficiency of new bone formation, especially at the initial stage after implantation. In long term (more than 12 weeks implantation), however, the pure scaffolds show as good biocompatibility and osteogenesis as the hybrid ones. All these results indicate that the scaffolds fulfill the basic requirements of bone tissue engineering scaffold, and have the potential to be applied in orthopedic, reconstructive and maxillofacial surgery.     

碳纤维增强纳米羟基磷灰石/聚酰胺66复合材料与动物体内骨组织的相容性

背景：碳纤维增强纳米羟基磷灰石/聚酰胺66复合材料相对于羟基磷灰石材料和其他纳米羟基磷灰石二元复合材料在力学强度、韧性和弹性模量等方面有了明显的提高,可用于承受载荷部位的骨缺损修复。 目的：评价新型生物复合材料碳纤维增强纳米羟基磷灰石/聚酰胺66在骨组织的生物相容性。 方法：使用巴马小型猪8只,在每只巴马小型猪的胸椎建立骨缺损模型并植入碳纤维增强纳米羟基磷灰石/聚酰胺66复合材料,在植入后8,16,24周处死动物并取材,行骨密度检测,胸椎椎体缺损处行苏木精-伊红染色。在植入前、植入后1,8周取血,查肝肾功能并进行对比。 结果与结论：植入后8周,椎体松质骨断端封闭,复合材料被肉芽组织包裹,椎体松质骨断端可见软骨细胞,界面间软骨成骨活跃。植入后16周,肉芽组织机化通过纤维内成骨方式生成新的骨组织并与骨端骨质大致融合。植入后24周,新生骨组织已成为成熟的板层骨,断端与复合材料结合紧密。植入复合材料的椎体骨密度在植入后8,16,24周的均数呈上升趋势(P < 0.05),随着植入时间增长,成骨量增加。植入前后的肝肾功能差异无显著性意义。实验可以初步认为碳纤维增强纳米羟基磷灰石/聚酰胺66是一种组织相容性、生物活性好,无肝肾毒性的新型骨缺损修复材料。     

Modified n-HA/PA66 scaffolds with chitosan coating for bone tissue engineering: cell stimulation and drug release

The dipping-drying procedure and cross-linking method were used to make drug-loaded chitosan (CS) coating on nano-hydroxyapatite/polyamide66 (nHA/PA66) composite porous scaffold, endowing the scaffold controlled drug release functionality. The prefabricated scaffold was immersed into an aqueous drug/CS solution in a vacuum condition and then crosslinked by vanillin. The structure, porosity, composition, compressive strength, swelling ratio, drug release and cytocompatibility of the pristine and coating scaffolds were investigated. After coating, the scaffold porosity and pore interconnection were slightly decreased. Cytocompatibility performance was observed through an in vitro experiment based on cell attachment and the MTT assay by MG63 cells which revealed positive cell viability and increasing proliferation over the 11-day period in vitro. The drug could effectively release from the coated scaffold in a controlled fashion and the release rate was sustained for a long period and highly dependent on coating swelling, suggesting the possibility of a controlled drug release. Our results demonstrate that the scaffold with drug-loaded crosslinked CS coating can be used as a simple technique to render the surfaces of synthetic scaffolds active, thus enabling them to be a promising high performance biomaterial in bone tissue engineering.     

新型人工生物活性接骨板治疗犬股骨骨折*◆

背景：研究表明纳米羟基磷灰石/聚酰胺66是一种具有良好的生物相容性、生物安全性、生物活性和骨传导能力的高强度高韧性复合材料。 目的：分析转染LIM矿化蛋白1基因的骨髓间充质干细胞复合纳米羟基磷灰石/聚酰胺66接骨板治疗犬股骨骨折的可行性和效果。 方法：收集犬骨髓间充质干细胞,经LIM矿化蛋白1转染后与纳米羟基磷灰石/聚酰胺66接骨板复合制备新型生物活性接骨板。48只杂交犬建立右侧股骨中段横形骨折模型,分别用转染/未转染LIM矿化蛋白1基因的骨髓间充质干细胞复合纳米羟基磷灰石/聚酰胺66接骨板、单纯纳米羟基磷灰石/聚酰胺66接骨板和钢板螺钉进行修复。 结果与结论：修复后8周及修复后12周转染组内固定失败率均低于未转染组和单纯接骨板组(P < 0.05),与钢板螺钉修复比较差异无显著性意义(P > 0.05)。转染组骨折愈合时间明显短于其他组。修复后12周转染组接骨板与犬股骨外侧皮质完全融合,骨干间有明显新骨生成。未转染组和单纯接骨板组未见或少量骨组织生成。说明新型生物活性接骨板能促进骨折愈合并与自体骨融合,不需要二次手术取出,但该新型接骨板的强度有一定的局限性,用于犬股骨骨折的治疗时必须辅加外固定。      

成骨诱导人脐带间充质干细胞与纳米羟基磷灰石/聚酰胺66支架材料的生物相容性☆

背景：纳米羟基磷灰石/聚酰胺66材料有利于成骨细胞的长入和新生骨的形成、且抗弯强度、抗压强度等各项参数与正常骨组织的力学性能相接近,能满足实验动物硬组织修复的要求。 目的：分析成骨诱导后人脐带间充质干细胞与纳米羟基磷灰石/聚酰胺66复合支架的生物相容性。 方法：体外培养人脐带间充质干细胞,纯化增殖,成骨诱导。取成骨诱导后的第3代人脐带间充质干细胞接种于纳米羟基磷灰石/聚酰胺66支架材料上,观察细胞的生长、增殖情况及材料细胞毒性。 结果与结论：成骨诱导后人脐带间充质干细胞在复合支架上生长分化良好,增殖活性不受材料影响。成骨诱导14 d内,可见碱性磷酸酶活性随着培养时间延长而逐渐增高。MTT法检测细胞无毒性。扫描电镜观察,1 d后可见细胞在支架表面附着生长;7 d后可见细胞在材料上生长良好,材料空隙有大量充填。说明纳米羟基磷灰石/聚酰胺66支架可作为骨组织工程中人脐带间充质干细胞的细胞载体,具有良好的生物相容性,能满足骨组织工程的需要。关键词：羟基磷灰石/聚酰胺66;人脐带间充质干细胞;细胞培养;骨组织工程;支架;生物相容性 缩略语注释：nHA/PA66：nano-hydroxyapatite crystals and pnolyamide 66,羟基磷灰石/聚酰胺66;hUCMSCs：human umbilical cord mesenchymal stem cells,人脐带间充质干细胞 doi:10.3969/j.issn.1673-8225.2012.16.019     

两种支撑体在脊髓型颈椎病椎体次全切减压融合术中应用的效果对比

目的　比较钛网与纳米羟基磷灰石/聚酰胺66（n-HA/PA66）颈椎支撑体植骨在颈椎椎体次全切、减压融合、前路钛板螺钉系统内固定术后,恢复维持颈椎曲度、椎间高度及融合率、沉降率的差异。 方法　75例确诊为两个相邻节段脊髓型颈椎病的患者行颈椎前路减压融合术,40例行钛网支撑体植骨,35例行n-HA/PA66颈椎支撑体植骨,均行椎前钉板系统内固定。比较两组手术时间、术中出血量、住院时间、JOA评分、颈椎曲度变化、融合节段椎间高度及植骨融合情况。分别摄术前、术后即刻、术后3、6、9个月颈椎标准侧位X线片,测量融合节段Cobb角、C2～7 Cobb角、D值评价颈椎的曲度,同时测量融合节段椎体前缘高度（HAB）、后缘高度（HPB）评价支撑体融合沉降情况,对各参数不同时期间差值分别行组间配对t检验。 结果　所有患者均获得随访,随访时间9~24个月（平均16.7个月）。两组患者术后的JOA评分明显高于术前,两组间JOA评分比较差异无统计学意义(P > 0.05)。两组患者术后即刻与术前D值差值有统计学意义(P <0.05),在术后3、6、9个月融合节段前后高上差异有统计学意义（P<0.05）,融合率上差异无统计学意义（P > 0.05）,而在术后6、9个月沉降率上差异有统计学意义（P < 0.05）,钛网组明显存在早期沉陷,影响融合节段椎间高度。 结论　n-HA/PA66颈椎支撑体相对于钛网支撑植骨具有提高融合率、并发症少等优点,可以有效保持颈椎生理曲度及椎间高度,是一种较为理想的支撑体植骨材料。     

纳米羟基磷灰石/聚酰胺66复合材料的研究及应用

背景：纳米羟基磷灰石在骨修复替代材料中有明显优势,但骨诱导活性低、力学性能差等缺陷限制了其临床应用。为克服弊端,国内外学者从仿生学等角度出发,以纳米羟基磷灰石为基础,掺杂、复合有机或无机材料,得到多种仿生复合材料。 目的：综述纳米羟基磷灰石/聚酰胺66复合材料的研究及应用进展。 方法：应用计算机检索1987年1月至2012年12月PubMed数据库相关文章,检索词为“nano,hydroxyapatite ,polyamide 66”。同时,计算机检索1987年1月至2012年12月中国期刊网全文数据库相关文章,检索词为“纳米,羟基磷灰石,聚酰胺66”。共检索到文献93篇,最终纳入符合标准的文献56篇。 结果与结论：纳米羟基磷灰石/聚酰胺66复合材料具有良好的热稳定性、生物力学性能及生物相容性。目前,纳米羟基磷灰石/聚酰胺66复合材料研究及引用主要集中于人工椎体、人工椎板及椎间融合器等,并取得了良好临床治疗效果,但仍有很多问题尚需要解决,如诱导成骨、降解情况都缺少长期而详尽的随访资料,而且目前主要是通过细胞学、组织学等方面来评价其生物安全性,尚未涉及到分子水平。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

多孔纳米羟基磷灰石/聚酰胺复合骨修复材料的制备

BACKGROUND: Compared with dense bone repair materials, porous materials has lower intensity, but its three-dimensional porous network structure can ensure a larger surface area that is more conducive to cell adhesion, growth and division as well as nutrient transmission. OBJECTIVE: To investigate the preparation and performance of porous nano-hydroxyapatite/polyamide composites. METHODS: Porous nano-hydroxyapatite/polyamide composites were prepared using chemical foaming method, and different composite bone repair materials were made by regulating foaming agent amount and nano-hydroxyapatite content. Mechanical properties, porosity and composition of the composite bone repair materials were detected. RESULTS AND CONCLUSION: Porous nano-hydroxyapatite/polyamide composites were substantially tubular  channels, and had relatively good connectivity and uniform distribution, with a pore size of 260-400 μm, porosity of 35%-57%. Foaming agent amount, nano-hydroxyapatite content and density of composite materials all are influential factors of the total porosity. Porous nano-hydroxyapatite/polyamide composites have better mechanical properties and compressive strength than the cancellous bone, and the foaming agent has no influence on its shape, composition and diffraction peaks.      

Antibacterial Chitosan Coating on Nano-hydroxyapatite/Polyamide66 Porous Bone Scaffold for Drug Delivery

This study describes a new drug-loaded coating scaffold applied in infection therapy during bone regeneration. Chitosan (CS) containing antibacterial berberine was coated on a nano-hydroxyapatite/polyamide66 (n-HA/PA66) scaffold to realize bone regeneration together with antimicrobial properties. The porous scaffold was fabricated using the phase-inversion method with a porosity of about 84% and macropore size of 400–600 μm. The morphology, mechanical properties and drug-release behavior were investigated at different ratios of chitosan to berberine. The results show that the elastic modulus and compressive strength of the coated scaffolds were improved to 35.4 MPa and 1.7 MPa, respectively, about 7 times and 3 times higher than the uncoated scaffolds. After a burst release of berberine within the first 3 h in PBS solution, a continuous berberine release can last 150 h, which is highly dependent on the coating concentration and suitable for antibacterial requirement of orthopaedic surgery. The bactericidal test confirms a strong antibiotic effect of the delivery system and the minimum inhibitory concentration of the drug is 0.02 mg/ml. Moreover, in vitro biological evaluation demonstrates that the coating scaffolds act as a good matrix for MG63 adhesion, crawl, growth and proliferation, suggesting that the antibacterial delivery system has no cytotoxicity. We expect the drug-delivery system to have a potential application in bone regeneration or defect repair.     

Enhanced Guided Bone Regeneration by Asymmetrically Porous PCL/Pluronic F127 Membrane and Ultrasound Stimulation

Abstract

Recently, we developed a novel method for fabricating a guided bone regeneration (GBR) membrane with an asymmetrical pore structure and hydrophilicity by an immersion precipitation method. Results from an animal study, in a cranial defect model in rats, indicated that the unique asymmetrically porous GBR membrane would provide a good environment for bone regeneration. In the present study, we applied low intensity pulsed ultrasound as a simple and non-invasive stimulus to an asymmetrically porous polycaprolactone (PCL)/Pluronic F127 GBR membrane-implanted site transcutaneously in rats to investigate the feasibility of using ultrasound to stimulate enhanced bone regeneration through the membrane. It was observed that the ultrasound-stimulated PCL/F127 GBR membrane group had much faster bone regeneration behavior than a PCL/F127 membrane group w/o ultrasound or a control group (w/o membrane and ultrasound). The greater bone regeneration behavior in the GBR membrane/ultrasound group may be caused by a synergistic effect of the asymmetrically porous PCL/F127 membrane with unique properties (selective permeability, hydrophilicity and osteoconductivity), and the stimulatory effect of ultrasound (induction of angiogenesis and osteogenesis of cells).     

Bone regeneration and infiltration of an anisotropic composite scaffold: an experimental study of rabbit cranial defect repair

Tissue formation on scaffold outer edges after implantation may restrict cell infiltration and mass transfer to/from the scaffold center due to insufficient interconnectivity, leading to incidence of a necrotic core. Herein, a nano-hydroxyapatite/polyamide66 (n-HA/PA66) anisotropic scaffold with axially aligned channels was prepared with the aim to enhance pore interconnectivity. Bone tissue regeneration and infiltration inside of scaffold were assessed by rabbit cranial defect repair experiments. The amount of newly formed bone inside of anisotropic scaffold was much higher than isotropic scaffold, e.g., after 12 weeks, the new bone volume in the inner pores was greater in the anisotropic scaffolds (>50%) than the isotropic scaffolds (<30%). The results suggested that anisotropic scaffolds could accelerate the inducement of bone ingrowth into the inner pores in the non-load-bearing bone defects compared to isotropic scaffolds. Thus, anisotropic scaffolds hold promise for the application in bone tissue engineering.     

人工椎体的组织相容性和力学性能

背景：近年来,随着组织工程学的发展,椎体替代材料趋于多样化,学者们不再满足于其能否恢复椎体高度与即刻稳定性,而是更为关注远期的融合,良好的组织相容性和力学性能。 目的：分析国内人工椎体的组织相容性和力学性能。 方法：以“人工椎体、相容性、生物力学”为检索词在中国期刊全文数据库中检索与人工椎体生物相容性和生物力学研究相关的文献进行分析。 结果与结论：人工椎体组织相容性的动物实验显示,纳米羟基磷灰石/聚酰胺66复合人工椎体成分和结构与人体骨相似,具有良好的生物相容性,成骨活性;可发生生物降解,其降解作用与成骨能力匹配。人工椎体的生物力学研究显示出纳米羟基磷灰石/聚酰胺66复合人工椎体不仅具有良好的生物活性,而且具有良好的轴向压缩载荷和椎间支撑能力,力学性能优异。生物陶瓷人工椎体不仅具有良好的生物相容性,而且在治疗椎体肿瘤中有靶向定位作用;金属材料的人工椎体经过多年的改进,其生物相容性亦可满足临床要求。就各类型人工椎体优劣而言,仍需进一步大量研究和实践,就其临床应用而言,需根据临床需要进行选择。     

A composite polymer/tricalcium phosphate membrane for guided bone regeneration in maxillofacial surgery

The aim of the study was the development of a resorbable membrane for guided bone regeneration (GBR) with improved biocompatibility, which should be stiff enough to avoid membrane collapse during bone healing. Combining a bioactive ceramic with a resorbable polymer may improve the biocompatibility and osteoconductivity of resorbable devices. The present article describes the preparation, the mechanical properties, and the in vitro degradation characteristic of a composite membrane made of poly(L, DL-lactide) and alpha-tricalcium phosphate in comparison to a membrane made of pure poly(L, DL-lactide). The tensile strength and the elastic modulus as well as the molecular weight of the membranes were measured after in vitro degradation in buffer at 37 degrees C up to 28 weeks. The initial tensile strength of the composite and the polymer membrane was 37.3 +/- 2.4 MPa and 27.7 +/- 2.3 MPa and the elastic modulus 3106 +/- 108 MPa and 3101 +/- 104 MPa, respectively. The mechanical properties remained constant up to 8 weeks and then decreased slowly until week 28. The molecular weight of both membranes decreased steadily from 170,000 D to 30,000 D. It was concluded that the mechanical requirements for a membrane for GBR were fulfilled by the composite membrane.     

Characterization and cytocompatibility of biphasic calcium phosphate/polyamide 6 scaffolds for bone regeneration

Porous scaffolds of biphasic calcium phosphate (BCP)/polyamide 6 (PA6) with weight ratios of 30/70, 45/55, and 55/45 have been fabricated through a modified thermally induced phase separation technique. The chemical structure properties, macrostructure, and mechanical strength of the scaffolds were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and mechanical testing. The results indicated that the BCP/PA6 scaffolds had an interconnected porous structure with a pore size mainly ranging from 100 to 900 μm and many micropores on the rough pore walls. The mechanical property of the scaffold was significantly enhanced by the addition of BCP inorganic fillers. The 55/45 BCP/PA6 composite scaffold with 76.5% ± 2.1% porosity attained a compressive strength of 1.86 ± 0.14 MPa. Moreover, the BCP/PA6 porous scaffold was cultured with rat calvarial osteoblasts to investigate the cell proliferation, viability, and differentiation function (alkaline phosphatase). The type I collagen expression was also used to characterize the differentiation of rat calvarial osteoblasts on BCP/PA6 composite scaffold by immunocytochemistry. The in vitro cytocompatibility evaluation demonstrated that the BCP/PA6 scaffold acted as a good template for the cells adhesion, spreading, growth, and differentiation. These results suggest that the BCP/PA6 porous composite could be a candidate as an excellent substitute for damaged or defect bone.