FePt/GO纳米复合材料制备方法及对胫骨骨折患者肢体功能的影响

目的:探讨FePt/GO纳米复合材料制备方法及对胫骨骨折患者肢体功能的影响。方法:采用化学还原法制备FePt/GO纳米复合材料,并从材料的热性能、抗吸湿性能及力学性能等评估制备材料的理化性能。选择124例胫骨骨折患者为对象,随机数字表法分为两组,各62例。对照组采用切开复位内固定术治疗,观察组采用FePt/GO纳米复合材料干预,术后对患者进行6个月随访,比较两组肢体功能、膝关节活动度。结果:FePt/GO纳米复合材料在10°~20°之间出现宽峰为FePt材料的弥散峰;在6°~15°出现的宽峰为GO材料的弥散峰;FePt/GO纳米复合材料中随着GO浓度的升高,拉伸特性降低;PBA份数为10份时拉伸强度比纯样品拉伸强度46.73 MPa下降18%;而复合材料的弯曲特性随着GO含量增加而增加;观察组术后6个月疼痛、功能、活动度评分及TPA和PA度数均高于对照组（P<0.05）。结论:采用化学还原法成功制备FePt/GO纳米复合材料,且制备材料具有良好的理化性能,用于胫骨骨折患者有助于改善患者肢体功能及关节活动度,能为胫骨骨折治疗提供新的材料。     

新型聚乳酸与纳米羟基磷灰石复合人工骨的性能测试研究

目的　通过原位聚合法制备新型的聚乳酸与纳米羟基磷灰石复合材料,找到两者复合的最佳配比,从而得到理想的人工骨移植材料。 方法　采用原位聚合法按一定的配比（纳米羟基磷灰石质量分数分别为0,10%,20%,30%,40%)聚乳酸与纳米羟基磷灰石复合人工骨,对这类新型的人工骨进行性能测试,通过抗弯,抗压,弹性模量,电镜扫描,体外降解实验,观测该人工骨的力学性能、微观结构、纳米羟基磷灰石在聚乳酸中的分散情况以及复合材料的降解性能。 结果　（1）力学测试显示：随着n-HA含量的增加,复合材料的拉伸强度逐渐减少。复合材料的弯曲强度在n-HA微粒的质量分数为20%时弯曲强度出现峰值(156.8 MPa)。复合材料的弯曲模量随着n-HA微粒质量分数的增加而增大。（2）SEM扫描显示：纯PDLLA材料断裂表面较平整;在n-HA含量为10%时出现大量的韧窝, 明显的粗糙断裂面;在n-HA含量为20%断裂表面凹凸不平,形成大量的韧窝;在n-HA含量为30%以上时断口又变得越来越平整,尚有许多小的韧窝。（3）体外降解实验显示：随着降解时间的延长,降解液的pH值均逐渐降低,复合材料的力学性能也逐渐的产生一定的衰减。 结论　当n-HA含量为20%时,该人工骨复合材料有着更好的力学性能和降解性能,筛选出该种新型人工骨的最佳配比,制备出性能良好的PDLLA/n-HA复合人工骨材料。     

羟基磷灰石/单壁碳纳米管复合材料的表征

背景：羟基磷灰石具有接近自然人骨的强韧度和优越的生物相容性,但其力学性能却较差。 目的：制成并研究一种新型生物活性材料(羟基磷灰石/单壁碳纳米管复合材料)的各种性质。 方法：利用原位合成法制备羟基磷灰石单壁碳纳米管复合材料,并对其红外光谱、微观结构及XDR衍射分析,力学性能进行测试,对不同SWNT含量的SWNT/HAp复合材料弯曲强度与断裂韧性比较分析。 结果与结论：成功制备出的纳米羟基磷灰石单壁碳纳米管复合材料,其抗弯强度最大增幅将近50%,达到73 MPa;而断裂韧性的最大提高幅度为3倍,达到2.6 MPa•m^1/2。随着单壁碳纳米管复合材料含量的增加,复合材料的弯曲强度与断裂韧性呈现出缓慢上升的趋势。提示,纳米羟基磷灰石单壁碳纳米管复合材料显著提高了接近自然人骨的纳米级磷灰石骨材料的抗弯强度和断裂韧性,从而克服传统支撑骨材料的力学性能缺陷。     

氨基改性人造颌骨纳米羟基磷灰石/聚乳酸复合材料的制备与表征

背景：口腔颌骨缺损修复常选择骨移植材料和人工骨替代材料两种,骨移植材料有其优点,但存在免疫反应、来源不足等缺陷,人工骨替代材料作为骨缺损修复材料的应用潜力巨大。目的：探讨侧链接枝氨基改性纳米羟基磷灰石/聚乳酸复合材料作为口腔人造颌骨材料的制备方法,并进行表征。方法：在纳米羟基磷灰石表面赋予氨基,再进行接枝改性,将接枝改性的纳米羟基磷灰石与聚乳酸复合,制作人造颌骨材料,复合材料中接枝改性纳米羟基磷灰石的含量分别为10%,30%,50%,表征材料的理化性能、机械力学性能与细胞相容性。结果与结论：(1)核磁氢谱、傅里叶变换红外光谱、X射线衍射及热失重分析显示,实验成功制备了氨基接枝改性的纳米羟基磷灰石材料;透射电镜下可见,氨基接枝改性的纳米羟基磷灰石材料有机溶剂N,N-二甲基甲酰胺中仍能以纳米尺寸分散,稳定的分散状态可以维持超过180 d;(2)扫描电镜下可见,当复合材料中的改性纳米羟基磷灰石含量为10%,30%时,显示出了优秀的纳米级分散效果;当含量为50%时,改性纳米羟基磷灰石不能均匀分散于聚乳酸体系中;(3)随着改性纳米羟基磷灰石含量的增加,材料的拉伸强度降低、弹性模量升高,综合考虑下...     

复合纳米人工骨的注射、凝固及其机械性能研究

目的 构建半水硫酸钙和纳米羟基磷灰石为主的复合人工骨材料并对其注射性能、凝固性能和机械强度的影响因素进行考察.方法 测试不同液固比条件下复合材料的注射特性,25℃和37℃时分别测试不同液固比、不同二水硫酸钙促凝剂条件下的材料初、终凝时间和压缩强度,均与纯硫酸钙作对比.结果 液固比0.50以上时注射性能满意.无论何种液/固比,复合材料的凝固时间均较硫酸钙延长,37℃下的凝固时间较25℃下延长.一定范围内促凝剂用量过大或过小均使凝固时间延长.液固比越大或促凝剂用量越高,材料压缩强度越低.纳米磷灰石含量增大则材料强度降低.结论 合理掌握纳米磷灰石的比例,液固比和促凝剂的用量,是开发可注射纳米人工骨的关键.     

nHA/α-CSH复合植骨材料的研制及其固化时间和抗压强度测定

目的构建纳米羟基磷灰石(nHA)/α型半水硫酸钙(α-CSH)复合植骨材料并对其固化性能和机械强度进行观测。方法测试不同液/固比、不同二水硫酸钙(CSD)促凝剂含量条件下复合植骨材料的固化时间和压缩强度,并进行X线衍射(XRD)和扫描电镜(ESM)观察。结果复合骨水泥的固化时间随着nHA的增加而增加,随着CSD的增加而降低。含20%nHA、80%α-CSH的骨修复材料固化时间为(169±36)min;而含5%nHA、20%CSD、75%α-CSH的骨修复材料固化时间为(6±1.1)min。抗压强度随着nHA的增加而降低。纯α-CSH的平均压缩强度为(12.3±2.4)MPa,而含20%nHA、80%α-CSH的骨修复材料为(4.8±0.6)MPa。XRD检测显示固化后α-CSH转化为CSD,没有其他物质生成。ESM显示固化后nHA镶嵌在了CSD的晶体结构上,呈两相结构。结论通过调节nHA、α-CSH和促凝剂CSD的含量可以控制复合骨水泥的固化时间和机械强度,为临床应用提供适宜条件。     

小口径微孔聚氨酯人造血管生物力学性能研究

目的分析小口径聚氨酯人造血管的微观形态,探讨聚氨酯人造血管管壁厚度对其渗透性能和拉伸强度的影响。方法通过在直径为4mm玻璃棒模具上复合均匀厚度的聚氨酯膜,并加入一定量的致孔剂,研制出具有微观多孔结构的小口径聚氨酯人造血管。采用扫描电镜表征其微观多孔结构,根据ISO7198国际标准设计了一套人造血管渗透性能的测试装置来测试其水渗透性能,并通过INSTRON万能强力仪(型号:5566)测试其拉伸强度。结果小口径的聚氨酯人造血管的内、外表面以及截面均呈微孔结构,微孔的大小在100μm以下,大小和分布比较均匀,并且随着人造血管壁厚度的增加,其渗透性能逐渐减小,拉伸强度先增大后减小,实验测试结果均与国外研究在同一范围。结论用聚氨酯材料研制的小口径人造血管在部分生物力学性能方面能满足人体血管置换要求。     

明胶/氧化纳米纤维素高弹性模量高孔隙皮肤支架的3D打印工艺

背景：在采用主动修复治疗手段应对皮肤创伤时，需要使用组织工程技术生成新的组织来代替坏死组织，皮肤支架在创伤修复领域具有良好的应用前景。皮肤支架需要呈现具有一定力学强度的三维多孔结构，以满足细胞增殖分裂的需求，而目前使用的明胶基生物材料力学强度弱，无法达到皮肤支架的使用要求。目的：针对明胶/氧化纳米纤维素复合材料制备组织工程皮肤支架时使用的3D打印工艺进行研究，重点研究不同工艺参数下制备皮肤支架的孔隙率与其力学强度之间的关系。方法：从葎草中提取10%浓度的氧化纳米纤维素晶须，再与5%的明胶复合得到明胶/氧化纳米纤维素复合材料，检测明胶与明胶/氧化纳米纤维素复合材料的弹性模量。以明胶/氧化纳米纤维素复合材料为基材，采用3D打印挤压成型方法制备皮肤支架，通过对材料进行力学性能测试和流变特性测试确定挤压成型工艺参数(填充间隙1.5-2.5 mm,0.1 mm均布；气压160-200 kPa)，并以此制备具有三维多孔结构的皮肤支架。对皮肤支架进行了抗压性能的测试并与有限元分析结果相对比，论证了支架打印时的填充间隙与支架孔隙率及力学强度之间的关系。结果与结论：(1)通过实验得出，加入10%浓度的氧...     

纳米磷灰石/聚D,L-乳酸生物复合材料制备与力学性能

目的观察溶液共混热压制备法能否提高纳米磷灰石(HA)/聚D,L-乳酸(PolyD,L杔actide,PDLLA)复合生物材料的力学性能。方法将HA/PDLLA分散至N,N-二甲基甲酰胺(DMF)有机溶剂中,在45℃下不断搅拌缓慢去除有机分散剂,干燥后打碎,放入模具中经100℃热压,获得纳米HA/PDLLA复合材料薄膜。结果透射电子显微镜(TEM)对不同含量的HA复合材料观察发现,纳米HA能被分散在PDLLA基材中。随着HA含量在复合材料中增加,HA出现了明显团聚现象,但总体上呈均匀的分布状态,说明热压前溶液共混处理有利于HA在复合材料中的分散。力学性能测试结果表明,上述溶液共混热压制备法能够增加HA与PDLLA的界面结合力,在合适的HA含量下,提高了材料的弹性模量、断裂应力及拉伸应力。结论溶液共混热压制备法能改善HA/PDLLA复合材料的力学性能。     

两种偶联剂改性纳米二氧化硅可影响树脂基托的力学性能

背景：聚甲基丙烯酸甲酯基托材料因其良好的生物相容性,色泽好,易于加工成型等优点被广泛使用,但因其韧性、硬度问题也存在容易折裂的不足。 目的：对比两种偶联剂改性的纳米SiO₂颗粒对聚甲基丙烯酸甲酯材料的弯曲强度、弯曲弹性模量和硬度改变。 方法：将两种偶联剂KH-570和KH-502改性的纳米SiO₂颗粒按质量比3%加入聚甲基丙烯酸甲酯粉体中制成(SiO₂/聚甲基丙烯酸甲酯)纳米复合材料。实验分为聚甲基丙烯酸甲酯材料、纳米SiO₂/聚甲基丙烯酸甲酯复合材料、KH-570-SiO₂/聚甲基丙烯酸甲酯复合材料、KH-502-SiO₂/聚甲基丙烯酸甲酯复合材料4组。 结果与结论：未经过偶联剂改性的纳米SiO₂/聚甲基丙烯酸甲酯复合材料与聚甲基丙烯酸甲酯材料相比,其弯曲强度、弯曲弹性模量和硬度差异无显著性意义(P > 0.05),而经过偶联剂改性的纳米SiO₂/聚甲基丙烯酸甲酯复合材料与聚甲基丙烯酸甲酯材料之间比较,其弯曲强度、弯曲弹性模量显著增强(P < 0.05),KH-502-SIO₂/PMMA组弯曲强度、弯曲弹性模量和硬度值显著大于与其他3组(P < 0.05)。结果表明,把经过偶联剂改性的纳米SiO2颗粒添加到聚甲基丙烯酸甲酯材料中制成SiO₂聚甲基丙烯酸甲酯复合材料,可使材料的弯曲强度、弯曲弹性模量和硬度明显提高。而经过偶联剂KH-502改性的纳米SiO₂聚甲基丙烯酸甲酯复合材料性能提高更为显著。     

Modification of Polyurethane with Polyethylene Glycol–Corn Trypsin Inhibitor for Inhibition of Factor Xlla in Blood Contact

Abstract

In previous work using gold as a model substrate, we showed that modification of surfaces with poly(ethylene glycol) (PEG) and corn trypsin inhibitor (CTI) rendered them protein resistant and inhibitory against activated factor XII. Sequential attachment of PEG followed by CTI gave superior performance compared to direct attachment of a preformed PEG-CTI conjugate. In the present work, a sequential method was used to attach PEG and CTI to a polyurethane (PU) substrate to develop a material with applicability for blood-contacting medical devices. Controls included surfaces modified only with PEG and only with CTI. Surfaces were characterized by water contact angle and X-ray photoelectron spectroscopy. The surface density of CTI was in the range of a monolayer and was higher on the PU substrate than on gold reported previously. Biointeractions were investigated by measuring fibrinogen adsorption from buffer and plasma, factor XIIa inhibition and plasma clotting time. Both the PU–PEG surfaces and the PU–PEG–CTI surfaces showed low fibrinogen adsorption from buffer and plasma, indicating that PEG retained its protein resistance when conjugated to CTI. Although the CTI density was lower on PU–PEG–CTI than on PU modified only with CTI, PU–PEG–CTI exhibited greater factor XIIa inhibition and a longer plasma clotting time, suggesting that PEG facilitates the interaction of CTI with factor XIIa. Thus sequential attachment of PEG and CTI may be a useful approach to improve the thromboresistance of PU surfaces.     

Degradation Behavior and Biocompatibility of PEG/PANI-Derived Polyurethane Co-polymers

A series of polyurethane (PU) co-polymers with designable molecular weight between cross-linking dots was synthesized by a hydrogen transfer polymerization route from polyaniline (PANI), poly(ethylene glycol) (PEG), various curing agents and chain extenders using dibutyltin dilaurate as a catalyst. Their swelling, hydrophilicity, degradation and biocompatibility were inspected and assessed based on different degrees of polymerization of PANI and PEG, and their component proportion. Fourier transformation infrared spectrometry (FT-IR), ¹H-NMR spectroscopy, scanning electron microscopy (SEM), gel-permeation chromatography (GPC) and goniometry were used to characterize the structure and surface morphology of the synthesized PEG/PANI-based PU co-polymers, PU residues after degradation and degraded polymers at different time periods of hydrolysis. The thermal properties, aggregate structure and surface microstructure were examined by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and atomic force microscopy (AFM). Hemolysis, static platelet adhesion, dynamic clotting measurements and MTT assays were adopted to evaluate the hemo- or cytocompatibility. The experimental results indicated that these polymers exhibit various degrees of micro-phase separation, depending on the concentration and degree of polymerization of PANI, molecular weight of PEG, type of curing agent and chain extender, which further influence their swelling, hydrophilicity, degradable properties and biological performances in vitro. The incorporation of PANI and PANI* in co-polymers led to decreased thermal stability but slower decomposition rates than typical PEG-based PUs. The stress–strain tests showed that the as-prepared PU co-polymers possessed increased tensile strength and modulus, and decreased toughness in comparison with the blank PEG-based PU. These co-polymers are expected to find specific applications in tissue engineering or controlled drug release.     

A comparative study on structure-property elucidation of P3/4HB and PEG-based block polyurethanes

A series of alternating block polyurethanes (abbreviated as PU3/4HB-alt-PEG) and random block polyurethanes (abbreviated as PU3/4HB-ran-PEG) based on biodegradable polyester poly(3-hydroxybutyrate-co-4-hydroxybutrate) (P3/4HB-diol) and poly(ethylene glycol) (PEG) with similar chemical compositions were synthesized using 1, 6-hexamethylene diisocyanate (HDI) as coupling agent. The chemical structure, molecular weight and distribution were characterized by FTIR, (1)H NMR, and GPC. The thermal differences were investigated by DSC. The hydrophilicity was studied by static contact angle and the results revealed that PU3/4HB-alt-PEG is more hydrophilic with a higher surface energy than PU3/4HB-ran-PEG. With SEM observation, PU3/4HB-alt-PEG exhibited a regular characterized microstructure with flower-type patterns on the surface, while PU3/4HB-ran-PEG displayed no regular pattern. A platelet adhesion study illustrated that PU3/4HB-alt-PEG possesses better hemocompatibility due to its more hydrophilic surface and evident surface microstructure. The cell culture assay demonstrated that fibroblasts and rat glial cells were more favorable for attachment on PU3/4HB-alt-PEG films. By comparison, alternating block polyurethanes provides a way to control the exact structure of the biomaterials and tailor better properties to biomedical requirements.     

紫杉醇聚合物纳米囊泡的制备和体外释放研究

目的 以聚己内酯-b-聚乙二醇-6-聚己内酯（PCEP）两亲性三嵌段共聚物为载体研制紫杉醇聚合物纳米囊泡.方法 以不同分子量的聚乙二醇（PEG）引发合成不同亲水段、疏水段链长的PCEP并进行FT-IR、1H NMR和GPC表征,以合成的嵌段聚合物PCEP为载体,通过薄膜-超声分散法制备紫杉醇聚合物纳米囊泡,用透射电子显微镜（TEM）表征其形态和构造,用粒度分析仪测定其粒径及分布,用高效液相色谱（HPLC）法测定其载药量及包封率,用透析袋法研究药物体外释放;同时,研究不同亲水链长、疏水链长对紫杉醇聚合物囊泡载药量、包封率、粒径及体外释放紫杉醇药物的影响.结果 研制的紫杉醇聚合物囊泡呈核-壳结构球形,粒径为纳米级,随着PCEP共聚物相对分子质量的增加而增大;紫杉醇聚合物囊泡体外释放无突释现象,能稳定缓慢释放紫杉醇,且释放速率随共聚物中亲水段PEG含量增加而增大,随疏水段PCL含量增大而减小.结论 以PCEP两亲性三嵌段共聚物为载体制备的紫杉醇聚合物纳米囊泡,其粒径小且分布均匀,包封率较高,有望成为一种用于提高紫杉醇的药效且降低不良反应的新的紫杉醇缓控释剂型.     

Fe3O4磁性微粒的制备及表征

背景：磁性微粒作为一种磁性载体在固定化酶、免疫检测、靶向载药治疗及细胞分离等生物医学领域得到了广泛的应用。 目的：制备分散稳定性好,相对磁性强的纳米级Fe₃O₄微粒。 方法：以氯化亚铁、氯化铁、氢氧化钠为主要原料,采用化学共沉淀法合成Fe₃O₄磁性粒子。 结果与结论：用正交设计法优化了Fe₃O₄微粒的合成工艺条件,得到制备Fe₃O₄粒子的最佳实验条件为Fe²⁺/Fe³⁺的物质的量之比为2∶1、共沉淀时的pH值为11、熟化温度为90 ℃、表面活性剂聚乙二醇的用量为40 mL,此时制得的Fe₃O₄粒子粒径最小,为78 nm,Fe₃O₄溶液的分散稳定性最好,相对磁性最强。从Fe₃O₄的扫描电镜图可以看出,Fe₃O₄微粒晶体颗粒为纳米级。     

Effect of cross-link density and hydrophilicity of PU on blood compatibility of hydrophobic PS/hydrophilic PU IPNs

To investigate the effect of the hydrophilic and hydrophobic microdomain structure on blood compatibility, a series of interpenetrating polymer networks (IPNs) composed of hydrophilic polyurethane (PU) and hydrophobic polystyrene (PS) was prepared. One series was prepared with varying cross-link densities of each network, the other with varying hydrophilicity of the PU component. All PU/PS IPNs exhibited microphase-separated structures that had dispersed PS domains in the continuous PU matrix. The domain size decreased with decreasing the hydrophilicity of the PU component and increasing the cross-link density of each network. As the cross-link density and hydrophobicity of the PU component was increased, an inward shift of T_gs was observed, which was due to the decrease in phase separation between the hydrophobic PS component and hydrophilic PU component. In the in vitro platelet adhesion test, as the microdomain size of PU/PS IPN surface decreased, the number of adhered platelets on the PU/PS IPN surface was reduced and deformation of the adhered platelets decreased. It could be concluded that blood compatibility of PU/PS IPN was mainly affected by the degree of mixing between PU and PS component, which was reflected by the domain size of PS rich phase.     

Single and dual crosslinked oxidized methacrylated alginate/PEG hydrogels for bioadhesive applications

A degradable, cytocompatible bioadhesive can facilitate surgical procedures and minimize patient pain and post-surgical complications. In this study a bioadhesive hydrogel system based on oxidized methacrylated alginate/8-arm poly(ethylene glycol) amine (OMA/PEG) has been developed, and the bioadhesive characteristics of the crosslinked OMA/PEG hydrogels evaluated. Here we demonstrate that the swelling behavior, degradation profiles, and storage moduli of crosslinked OMA/PEG hydrogels are tunable by varying the degree of alginate oxidation. The crosslinked OMA/PEG hydrogels exhibit cytocompatibility when cultured with human bone marrow-derived mesenchymal stem cells. In addition, the adhesion strength of these hydrogels, controllable by varying the alginate oxidation level and measured using a porcine skin model, is superior to commercially available fibrin glue. This OMA/PEG hydrogel system with controllable biodegradation and mechanical properties and adhesion strength may be a promising bioadhesive for clinical use in biomedical applications, such as drug delivery, wound closure and healing, biomedical device implantation, and tissue engineering.     

Synthesis of polyetherurethanes containing L-serine dipeptide and their use as materials for biomedical films

Prepolymers, which were produced by the polyaddition reaction of polytetramethylene glycol (PTMG) or polyethylene glycol (PEG) and 4,4'-diphenylmethane diisocyanate (MDI) or hexamethylene diisocyanate (HMDI), were chain-extended with a linear dipeptide of L-serine (Z-Ser-Ser-OMe) or a cyclic dipeptide of L-serine [c-(Ser)2] to yield novel polyetherurethanes containing dipeptide segments. The relationship between the surface morphology and the biomedical properties of the film of the novel polyetherurethanes was investigated. The surface of PU(PTMG,Z-Ser-Ser-OMe,MDI) film was smooth, but fibrous structures were developed in the bulk of the film with increasing molecular weight of the PTMG segment. The antithrombogenicity of the film containing the low molecular weight PTMG segment was better than that of the usual polyetherurethane film without the dipeptide segments. The partial hydrolysis of the ester groups involved in the dipeptide segment improved the antithrombogenicity. In the surface and the bulk of PU[PTMG,c-(Ser)2,MDI] film, spherulite structures were developed when the molecular weight of the PTMG segment was high, while single crystals with a length of 3-4 microns were produced when the molecular weight of the PTMG segment was low. The antithrombogenicity of the film containing the high molecular weight PTMG segment was better than that of the usual polyetherurethane film without the dipeptide segments. PU(PTMG/PEG,Z-Ser-Ser-OMe,MDI) film and PU[PTMG/PEG,c-(Ser)2,MDI] film were permeated by uraemic toxins. The permeation was accelerated with increasing water content of the film and decreasing molecular weight of the solute. The oxygen permeability of the film of the polyetherurethane containing the linear or cyclic dipeptide segments was greater than that of polyetherurethane film which does not contain the dipeptide segments.     

Biocompatible, glucose-permeable hydrogel for in situ coating of implantable biosensors

A glucose-permeable hydrogel (97% water by mass) was formed by cross-linking an 8-armed, amineterminated poly(ethylene glycol) (PEG) derivative with a di-succinimidyl ester of an ,ω-dipropionic acid derivative of PEG in aqueous solution at room temperature. The gel was evaluated as a biocompatible interface between an amperometric glucose electrode and the subcutaneous tissue of a rat. Over a glucose concentration range of 0–30 mM, the loss in sensitivity to glucose caused by the application of the hydrogel was 34% and the reduction in limiting current at high glucose concentration (30 mM) was 35% at 37 °C for films that were approximately 0.06mm thick, an acceptable loss. Hydrogel and Pellethane^TM samples were subcutaneously implanted in male Sprague-Dawley rats for 7 days. The explanted samples were thin-sectioned, stained and examined under a light microscope. While the Pellethane^TM samples were encapsulated with tissue consisting of macrophages, neutrophils, foreign body giant cells, fibroblasts and collagen, the PEG samples had very few adherent cells. The results show this system to be a good candidate for providing biocompatible interfaces for sensors, especially oxidoreductase-based sensors.     

Physicochemical and Biological Properties of Nano-hydroxyapatite-Reinforced Aliphatic Polyurethanes Membranes

Polymer nano-composite membranes, based on aliphatic biodegradable polyurethane (PU) elastomers and nano-hydroxyapatite (n-HA), were prepared by solvent casting and freeze-drying. The PU matrix was synthesized from 4,4′-dicyclohexylmethane diisocyanate (H₁₂ MDI), poly(ethylene glycol) (PEG), castor oil (CO) and 1,4-butandiol (BDO). The n-HA/PU membranes were characterized by SEM, XRD, IR, TG, mechanical test and in vitro biocompatibility. The results revealed that incorporation of 30 wt% n-HA into the PU matrix increased the tensile strength nearly by 186% and the elongation-at-break by 107% compared to pure PU. The addition of n-HA had the slight positive effect on the thermal stability of PU. Cell culture and MTT assays showed that the incorporation of n-HA into the PU matrix provided a favourable environment for initial cell adhesion, maintained cell viability and cell proliferation. These results suggested that the n-HA/PU composite membrane might be a prospective biodegradable guided bone regeneration (GBR) membrane for future applications.