笼型Li6Si5团簇的结构和储氢性能研究

利用密度泛函M06方法,在6-311+G(d, p)基组水平上对Si_5和Li修饰的Si_5团簇的几何结构和电子性质及储氢性能进行理论计算研究.结果表明, Si_5团簇最低能量构型为笼型结构,纯Si_5团簇不能有效吸附氢分子. Li原子的引入显著改善了Si_5团簇的储氢能力.以六个Li原子穴位修饰Si_5团簇为载体,每个Li原子周围可以有效吸附三个氢分子,其氢分子的平均吸附能为2.395 kcal/mol,储氢密度可达16.617 wt%.合适的吸附能和较高储氢密度表明Li修饰Si_5团簇有望成为理想的储氢材料.     

Haversian bone-mimicking bioceramic scaffolds enhancing MSC-macrophage osteo-imunomodulation

The interaction between immune cells and bone forming cells plays a vital role in maintaining the homeostasis of the skeletal system, and is regulated by the three-dimensional structure of tissues. Whether the construction of biomaterials can activate or reproduce this spatial “cross-talk” between immune cells and bone forming cells in bone natural formation process is a prerequisite for successful fracture healing and bone regeneration. Herein, a bone marrow mesenchymal stem cells (MSCs)/macrophages-laden Haversian bone-mimicking bioceramic scaffold was successfully prepared through the biomimetic design of biomaterials and 3D printing technology. MSCs and macrophages were respectively distributed in the cancellous bone and Haversian canals of the scaffold to simulate the three-dimensional structure regulation of the cell spatial distribution and multiple intercellular interaction in natural bone tissue, and worked in concert to modulate the scaffold material-mediated osteo-immune microenvironment. The in vitro study revealed that the pro-inflammatory response of macrophages was more significantly inhibited when distributed with MSCs in the scaffolds at a cell ratio of 0.5:1 for co-culture, in comparison with multicellular culture at other ratios and unicellular culture. Meanwhile, MSCs exhibited the relatively high osteogenic potential, most likely via the activation of certain key signaling pathways mediated by macrophages-derived paracrine signaling mediators (OSM, BMP-2, and WNT10b). This work not only establishes a bionic platform for the regulation of multicellular osteo-immune response and regeneration but also offers a promising tissue-engineered biomimetic scaffold with improved immunomodulatory function for promoting bone tissue regeneration.     

BMSCs过表达BMP-4复合同种异体骨修复软骨缺损

目的 针对关节软骨损伤后修复困难,采用腺病毒(Ad)载体介导骨形态发生蛋白(BMP-4)修饰骨髓间充质干细胞(BMSCs),并复合同种异体骨软骨柱支架,以期实现关节软骨有效再生.方法 制备同种异体骨软骨柱,BMSCs过表达BMP-4复合同种异体骨修复关节软骨损伤,膝关节标本取材大体观察及分析,HE、番红固绿、Masso...     

骨组织工程聚左旋乳酸多孔框架快速成形研究

为制备用于骨组织工程的细胞载体框架结构 ,对快速成形技术制备聚左旋乳酸多孔框架结构的若干基础问题进行了研究。提出了聚左旋乳酸快速成形的精密挤出成形工艺 ,研究了此工艺制备多孔框架结构的设备与工艺过程 ,分析了制备的多孔框架结构应用于组织工程人工骨的可行性。制备的多孔框架结构具有合适的分子量、孔隙结构、孔隙率、机械强度和生物降解性能 ,可以用作骨组织工程的组织再生框架结构     

晶须表面改性及其填充聚醚醚酮摩擦学行为

利用溶胶-凝胶(sol-gel)、氟表面活性剂(FSO)和钛酸酯偶联剂(NDZ-102)等对钛酸钾晶须(PTW)进行了表面改性,对比了改性后水接触角的变化,考察了干摩擦条件下PTW改性对聚醚醚酮(PEEK)复合材料摩擦磨损性能的影响. 利用SEM和光学显微镜观察了磨损面和对偶面转移膜形貌,并分析了其磨损机理. 实验结果表明:改性后PTW的水接触角均有不同程度的提高,FSO改性得最高;改性后PEEK复合材料的摩擦因数均降低,在各载荷下FSO和溶胶-凝胶改性PTW后PEEK复合材料耐磨性明显优于未改性的,300 N载荷下较未改性的分别提高2.64和2.11倍;但是NDZ-102改性却降低了复合材料的耐磨性.     

纳米Al2O3和聚四氟乙烯填充聚醚醚酮基复合材料摩擦学特性研究

以热压成型法制备了纳米Al2 O3 和聚四氟乙烯 (PTFE)填充聚醚醚酮基 (PEEK)复合材料 ,利用销盘摩擦磨损试验机研究了干摩擦条件下纳米Al2 O3 和PTFE填充PEEK的摩擦磨损特性。结果表明 ,纳米Al2 O3 使PTFE填充PEEK复合材料的摩擦磨损特性得到明显改善 ,其改善程度与纳米Al2 O3 的填充量有关 ,当纳米Al2 O3 的含量较低 (3% )时 ,纳米Al2 O3 PTFE PEEK复合材料与钢对偶面产生的磨损模式以磨粒磨损和犁削为主 ;而当纳米Al2 O3 的含量较高 (10 % )时 ,纳米Al2 O3 填充PEEK的磨损模式主要是粘着磨损 ;纳米Al2 O3 的含量为 5 %～ 7%时 ,PEEK复合材料的摩擦系数和比磨损率最低。随着载荷的增加 ,纳米Al2 O3 PTFE PEEK复合材料的摩擦系数将因纳米粒子效应和表面摩擦温升呈现下降趋势     

Comparative study of microstructural remodification to porous β-TCP and HA in rabbits

To assess the remolding ability of repaired bone in hydroxyapatite （HA） and β-calcium phosphate （β-TCP） scaffold, two 75% porosity bioceramics with the same three-dimensional geometry were implanted into femoral condyles of rabbits. Histological and micro-computed tomography （micro-CT） results demonstrated abundant new bone formation in the porous HA scaffold along with indistinctive scaffold degradation. Results also indicated that scaffold resorption in the β-TCP group, which was followed by a replacement with newly formed bone, was significantly higher than that in the HA group. The crosslinking trabeculae remodeled from the mixtures of the newly formed bone and β-TCP scaffold remnants might be helpful to promoting even loading and reducing stress. The bone remodeling pattern resulted from bone formation and scaffold resorption was significantly different for the two bioceramics. The results demonstrated that the 75% porous β-TCP was more suitable for new bone remodification than HA scaffold.     

氯化聚乙烯在聚氯乙烯产品中的作用

从共混体系相容性、共混物形态与性能的关系、影响共混物形态及冲击强度的因素等方面,阐述了氯化聚乙烯在改善聚氯乙烯制品的冲击性能方面的应用。     

血管内皮生长因子(VEGF)与肝再生

血管内皮生长因子(vascularendothelialgrowthfactor,VEGF)能特异地直接作用于血管内皮细胞,刺激血管内皮细胞的分裂、增殖并诱导血管的形成.它通过与血管内皮细胞的受体结合发挥作用.肝受到各种损伤包括部分肝切除后,肝再生就得以启动.在肝再生过程中,VEGF对内皮细胞的生长增殖起有效促进作用,并且能诱导组织胶原酶、血纤维蛋白酶原的激活,增加血管的通透性,这对血管再生起着极其重要的作用.而血管再生是肝再生的一个重要组成部分,它不仅能给肝细胞提供血液支持,而且能促进肝脏结构的重构.因此VEGF在肝再生过程中具有重要的作用.     

干细胞与心肌再生

由于成年心肌细胞通常不能再生,严重的心肌损伤会导致心肌不可逆的重构坏死, 从而发生心功能失调. 干细胞再生治疗为心肌再生提供了很好的策略. 为了寻找合适的干细胞类型, 促进心肌再生, 有效改善心功能, 需要更好地了解心肌修复和再生的分子基础. 已有研究发现多种干细胞可促进心肌再生. 描述了骨髓干细胞的促血管新生及心肌分化的能力在心梗治疗中的作用, 还讨论了心脏侧群干细胞以及诱导型多能干细胞在心肌再生中的作用和分子机制. 所阐述的最新数据有利于拓展干细胞治疗的有效潜能及临床影响.     

聚醚醚酮基复合材料的摩擦学研究进展

聚醚醚酮 (PEEK)基复合材料是一类重要的高性能热塑性聚合物 ,在工程中有重要的应用价值。论述了不同实验条件下PEEK基复合材料的摩擦和磨损特性 ,讨论了复合材料的不同结构和组成对其摩擦磨损特性的影响。主要分析了聚四氟乙烯 (PTFE)、聚醚酰亚胺 (PEI)、热致液晶聚合物 (TLCP)以及无机颗粒增强剂 (包括纳米粒子 )和纤维填料 (玻璃纤维GF和碳纤维CF)对PEEK摩擦学特性的影响。并对PEEK改性手段的现状及前景进行了分析。     

Electrospun Nanofibers of Hydroxyapatite/Collagen/Chitosan Promote Osteogenic Differentiation of BMSCs

Bone tissue engineering, aiming at developing bone substitutes for repair and regeneration of bone defects instead of using autologous bone grafts, has attracted wide attention in the field of tissue engineering and regenerative medicine. Developing biomimetic biomaterial scaffolds able to regulate osteogenic differentiation of stem cells could be a promising strategy to improve the therapeutic efficacy. In this study, clectrospun composite nanofibers of hydroxyapatite/collagen/chitosan （ HAp/Col/CTS ） resembling the fibrous nanostructure and constituents of the hierarchically organized natural bone, were prepared to investigate their capacity for promoting bone mesenchymal stem cells （BMSCs） to differentiate into the osteogenic lineage in the absence and presence of the osteogenlc supplementation, respectively. Call morphology, proliferation and quantified specific osteogenic protein expression on the electrospun HAp/Coi/CTS scaffolds were evaluated in comparison with different controls including dectrospun nanofibrous CTS, HAp/CTS and tissue culture plate. Our remits showed that the nanofibrous HAp/Col/CTS scaffolds supported better spreading and proliferation of the BMSCs than other substrates （ P 〈 0.01 ）. Expressions of osteogenesis protein markers, alkaline phosphatase （ALP） and Col, were significantly upregulated on the HAp/Col/CTS than those on the CTS （P 〈0.01） and HAp/ CTS （P 〈 0. 05 ） scaffolds in the absence of the osteogeulc supplementation. Moreover, presence of osteogeulc supplementation also proved to enhance osteogeule differentiation of BMSCs on HAp/ Col/CTS scaffolds, indicative of a synergistic effect. This study highlights the potential of BMSCs/HAp/Col/CTS cell-scaffold system for functional bone repair and regeneration applications.     

骨粉/PLLA新型内固定复合材料的制备

用骨粉和聚-L-乳酸复合制得骨粉／PLLA内固定复合材料,研究骨粉加入量对复合材料的力学性能的影响,对骨粉进行粒度分析和红外光谱分析,对制得的复合材料进行XRD和SEM表征。研究结果表明：所用骨粉为超微米级颗粒,可为其与聚-L-乳酸基体材料提供很大的接触面积,增加复合材料的力学性能;脱脂脱蛋白皮质骨粉主要含有羟基磷灰石,大量的蛋白质等有机化合物均被除去;由于骨粉的加入使复合材料的结晶度和抗弯强度有所降低,而弹性模量有所升高,不同含量骨粉的复合材料的抗弯断口形貌也发生了变化;所得骨粉／PLLA复合材料具有良好的生物活性,是骨科内固定器件中的理想可降解生物材料。     

构树剥皮再生中内源IAA的变化及其组织定位

用酶联免疫吸附法研究了构树(Broussonetia papyrifera (L.)Vent.)剥皮后维管组织再生过程中内源IAA浓度的变化,并用改进的免疫金银法测定了此过程中内源IAA在不同组织中的分布。结果表明,剥皮后内源IAA浓度迅速升高,升高幅度近100%。去除树冠和遮光抑制了维管组织的再生,但却没有影响内源IAA浓度的变化趋势。这似表明,剥皮刺激诱导的内源IAA浓度的快速升高可能是束缚态IAA的快速释放,而不是芽和幼叶新合成的结果。内源IAA组织定位的结果表明射线细胞、愈伤组织和新生维管组织内均有较多的银颗粒标记。这些似可表明,高浓度的内源IAA可启动未成熟维管组织细胞的脱分化,而较低浓度的内源IAA流则可诱导再生形成层的发生和活动。     

纳米仿生骨组织材料的生理响应及生物矿化

利用溶胶－凝胶法合成了两种具有纳米结构的新型高生物活性骨修复及骨组织工程支架材料，并利用体外实验方法（In Vitro)以及X－射线衍射（XRD），扫描电子显微镜（SEM），红外光谱（FTIR），氮气吸附－解吸（BET）和等离子发射光谱（ICP）等技术对材料的显微结构及其在模拟生理溶液（SBF）中的降解过程，表面反应产物及生物矿化机理进行了研究，研究表明：两种溶胶－凝胶材料均具有较高的生物活性；由于化学组成不同，它们在SBF溶液中的离子扩散规律及生物矿化行为有所不同。     

聚醚醚酮/聚酯液晶二元和三元增容共混体系的等温结晶动力学及结晶形态

采取熔融共混方法制备了聚醚醚酮（PEEK）和聚酯液晶（TLCP）二元和三元增容共混物, 用DSC和PLM对 共混物的结晶行为和结晶形态进行了研究. 结果表明, TLCP的存在使PEEK的结晶温度和结晶起始温度均略有升高, 增容剂（RCP）的加入延缓了PEEK结晶过程. 等温结晶动力学研究表明, 液晶的加入加快了聚醚醚酮的结晶速度, 但随其含量增加结晶速度降低. 与二元共混物相比, 加入增容剂后对聚醚醚酮的结晶速度基本无影响. 增容后的聚醚醚酮球晶的尺寸下降, 很难看到Maltese十字消光.     

热致相分离法制备聚醚醚酮多孔膜

对聚醚醚酮/二苯砜、聚醚醚酮/二苯酮所组成聚合物/稀释剂体系,采用热致相分离法制备了聚醚醚酮多孔膜,探讨了制备具有耐高温、耐溶剂的聚醚醚酮多孔膜的可能性,对聚合物/稀释剂体系的相容性进行理论计算和分析,并研究了聚合物的含量对成膜多孔结构的影响。     

Haematopoietic stem cells adopt mature haematopoietic fates in ischaemic myocardium

Under conditions of tissue injury, myocardial replication and regeneration have been reported. A growing number of investigators have implicated adult bone marrow (BM) in this process, suggesting that marrow serves as a reservoir for cardiac precursor cells. It remains unclear which BM cell(s) can contribute to myocardium, and whether they do so by transdifferentiation or cell fusion. Here, we studied the ability of c-kit-enriched BM cells, Lin- c-kit+ BM cells and c-kit+ Thy1.1(lo) Lin- Sca-1+ long-term reconstituting haematopoietic stem cells to regenerate myocardium in an infarct model. Cells were isolated from transgenic mice expressing green fluorescent protein (GFP) and injected directly into ischaemic myocardium of wild-type mice. Abundant GFP+ cells were detected in the myocardium after 10 days, but by 30 days, few cells were detectable. These GFP+ cells did not express cardiac tissue-specific markers, but rather, most of them expressed the haematopoietic marker CD45 and myeloid marker Gr-1. We also studied the role of circulating cells in the repair of ischaemic myocardium using GFP+-GFP- parabiotic mice. Again, we found no evidence of myocardial regeneration from blood-borne partner-derived cells. Our data suggest that even in the microenvironment of the injured heart, c-kit-enriched BM cells, Lin- c-kit+ BM cells and c-kit+ Thy1.1(lo) Lin- Sca-1+ long-term reconstituting haematopoietic stem cells adopt only traditional haematopoietic fates.     

Oxidative stress induces angiogenesis by activating TLR2 with novel endogenous ligands

Reciprocity of inflammation, oxidative stress and neovascularization is emerging as an important mechanism underlying numerous processes from tissue healing and remodelling to cancer progression. Whereas the mechanism of hypoxia-driven angiogenesis is well understood, the link between inflammation-induced oxidation and de novo blood vessel growth remains obscure. Here we show that the end products of lipid oxidation, ω-(2-carboxyethyl)pyrrole (CEP) and other related pyrroles, are generated during inflammation and wound healing and accumulate at high levels in ageing tissues in mice and in highly vascularized tumours in both murine and human melanoma. The molecular patterns of carboxyalkylpyrroles are recognized by Toll-like receptor 2 (TLR2), but not TLR4 or scavenger receptors on endothelial cells, leading to an angiogenic response that is independent of vascular endothelial growth factor. CEP promoted angiogenesis in hindlimb ischaemia and wound healing models through MyD88-dependent TLR2 signalling. Neutralization of endogenous carboxyalkylpyrroles impaired wound healing and tissue revascularization and diminished tumour angiogenesis. Both TLR2 and MyD88 are required for CEP-induced stimulation of Rac1 and endothelial migration. Taken together, these findings establish a new function of TLR2 as a sensor of oxidation-associated molecular patterns, providing a key link connecting inflammation, oxidative stress, innate immunity and angiogenesis.     

不同端基的聚醚醚酮的分子量控制及端基对热稳定性的影响

本文合成了羟端、氟端和苯端三种不同端基的聚醚醚酮.结果表明,无活性的苯端聚醚醚酮具有最好的热稳定性.