SCANNING ELECTRON MICROSCOPIC STUDY OF FETAL CHICKEN CALVARIAL OSTEOBLAST-LIKE CELLS CULTURED IN VITRO

Three types of osteoblast-like cells with different cnfigurations could be ob-tained through culturing fetal chicken calvaria in vitro. They were spindle-shaped cells,globular cells, and polygonal or squamous cells. With passage of culture time, there werechanges in configuration so that the spindle-shaped cells and the globular cells turnedgradually into squamous cells, in quantity which increased greatly to produce confluenceand multi-layer formation of cells, and in function as evidenced by emergence ofintracytoplasmic granules, reflecting collagen synthesis.

TiO₂Nanoparticles Induced Genotoxicity in Cultured Cells Using Atmospheric Scanning Electron Microscopy (ASEM)

Nano-sized titanium oxide nanoparticles (TiO2 NPs) are widely used as a dye in food and cosmetics. TiO2 NPs are known to induce DNA damage when incorporated into cells. However, no bioassay is currently available to easily determine the cell incorporation of TiO2 NPs or related DNA damage, and to date, few studies have examined the different degrees of incorporation into cells according to the size of the TiO2 NPs particles and the presence or absence of cell specificity regarding DNA damage. This present study was therefore designed to examine COS7 cells that had incorporated TiO2 NPs using atmospheric scanning electron microscopy (ASEM). The results indicated that absorption of TiO2 NPs into cells and nuclear abnormalities had occurred. ASEM is a rapid and simple technique that enables the observation of samples immediately after fixation with glutaraldehyde and staining with phosphotungstic acid, and this method was suggested to be useful in screening for DNA damage.

Mesenchymal stem cells and collagen patches for anterior cruciate ligament repair

AIM: To investigate collagen patches seeded with mesenchymal stem cells(MSCs) and/or tenocytes(TCs) with regards to their suitability for anterior cruciate ligament(ACL) repair. METHODS: Dynamic intraligamentary stabilization utilizes a dynamic screw system to keep ACL remnants in place and promote biological healing, supplemented by collagen patches. How these scaffolds interact with cells and what type of benefit they provide has not yet been investigated in detail. Primary ACL-derived TCs and human bone marrow derived MSCs were seeded onto two different types of 3D collagen scaffolds, Chondro-Gide?(CG) and Novocart?(NC). Cells were seeded onto the scaffolds and cultured for 7 d either as a pure populations or as "premix" containing a 1:1 ratio of TCs to MSCs. Additionally, as controls, cells were seeded in monolayers and in co-cultures on both sides of porous high-density membrane inserts(0.4 μm). We analyzed the patches by real time polymerase chain reaction, glycosaminoglycan(GAG), DNA and hydroxyproline(HYP) content. To determine cell spreading and adherence in the scaffolds microscopic imaging techniques, i.e., confocal laser scanning microscopy(c LSM) and scanning electron microscopy(SEM), were applied.RESULTS: CLSM and SEM imaging analysis confirmed cell adherence onto scaffolds. The metabolic cell activity revealed that patches promote adherence and proliferation of cells. The most dramatic increase in absolute metabolic cell activity was measured for CG samples seeded with tenocytes or a 1:1 cell premix. Analysis of DNA content and c LSM imaging also indicated MSCs were not proliferating as nicely as tenocytes on CG. The HYP to GAG ratio significantly changed for the premix group, resulting from a slightly lower GAG content, demonstrating that the cells are modifying the underlying matrix. Real-time quantitativepolymerase chain reaction data indicated that MSCs showed a trend of differentiation towards a more tenogenic-like phenotype after 7 d.CONCLUSION: CG and NC are both cyto-compatible with primary MSCs and TCs; TCs seemed to perform better on these collagen patches than MSCs.

Influence of PTFE on Electrode Structure for Performance of PEMFC and 10-Cells Stack

Water plays a critical role on the performance, stability and lifetime of proton exchange membrane fuel cells（PEMFCs）. The addition of poly tetrafluoroethylene（PTFE） to the gas diffusion layer, especially, the cathode side, would optimize the transportation of water, electron and gas and thus improve the performance of the fuel cell. But until now, the studies about directly applying the PTFE to the catalyst layer are rarely reported. In this paper, the membrane electrode is fabricated by using directly coating catalyst to the membrane method（CCM） and applying PTFE directly to the cathode electrode catalyst layer. The performance of the single cell is determined by polarization curves and durability tests. Electrochemical impedance spectroscopy（EIS） and scanning electron microscopy（SEM） techniques are used to characterize the electrochemical properties of PEMFC. Also the performance of a 10-cells stack is detected. Combining the performance and the physical-chemistry characterization of PEMFC shows that addition of appropriate content of PTFE to the electrode enhances the performance of the fuel cell, which may be due to the improved water management. Addition of appropriate content of PTFE enhances the interaction between the membrane and the catalyst layer, and bigger pores and highly textured structure form in the MEA, which favors the oxygen mass transfer and protons transfer in the fuel cell. While superfluous addition of PTFE covers the surface of catalysts and hindered the contact of catalyst with Nation, which leads to the reduction of electrochemical active area and the decay of the fuel cell performance. The proposed research would optimize the water management of the fuel cell and thus improve the performance of the fuel cell.

Recent progress on advanced transmission electron microscopy characterization for halide perovskite semiconductors

Halide perovskites are strategically important in the field of energy materials. Along with the rapid development of the materials and related devices, there is an urgent need to understand the structure–property relationship from nanoscale to atomic scale. Much effort has been made in the past few years to overcome the difficulty of imaging limited by electron dose,and to further extend the investigation towards operando conditions. This review is dedicated to recent studies of advanced transmission electron microscopy(TEM) characterizations for halide perovskites. The irradiation damage caused by the interaction of electron beams and perovskites under conventional imaging conditions are first summarized and discussed. Low-dose TEM is then discussed, including electron diffraction and emerging techniques for high-resolution TEM(HRTEM) imaging. Atomic-resolution imaging, defects identification and chemical mapping on halide perovskites are reviewed. Cryo-TEM for halide perovskites is discussed, since it can readily suppress irradiation damage and has been rapidly developed in the past few years. Finally, the applications of in-situ TEM in the degradation study of perovskites under environmental conditions such as heating,biasing, light illumination and humidity are reviewed. More applications of emerging TEM characterizations are foreseen in the coming future, unveiling the structural origin of halide perovskite’s unique properties and degradation mechanism under operando conditions, so to assist the design of a more efficient and robust energy material.

Comparative ultrastructural study of endoplasmic reticulum in colorectal carcinoma cell lines with different degrees of differentiation

The endoplasmic reticulum (ER) consists of a complex system of tubules, lamellae, and flattened vesicles, and has a variety of morphologies in different cells. It is believed to play a central role in the biosynthesis of cholesterol, phospholipids, steroids, prostaglandins, membrane and secretory proteins[1]. Cancer cells have different functions and ultrastmcture from their original cells[2-4]. The studies on ER membrane system of cancer cells are of great significance in understanding their malignant behavior. In the present work, the ultrastructural characteristics of ER in human colorectal carcinoma cell lines with different differentiation degrees were investigated.

Cytotoxicity assessment of a gold nanoparticle-chitosan nanocomposite as an efficient support for cell immobilization:comparison with chitosan hydrogel and chitosan-gelatin

Cell-based biosensors have become a research hotspot in the biosensors and bioelectronics fields. The main feature of cell-based biosensors is immobilization of living cells on the surface of transducers. Different types of polymers which are used as scaffolds for cell growth should be biocompatible and should have reac- tive functional groups for further attachment of biomolecules. In this work, cell attachment and proliferation on chitosan hydrogel, chitosan-gelatin and gold nanoparticle-chitosan nanocomposite membranes was stud- ied. Characterization of the membranes was performed using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Cytotoxicity assessment on HEK293 cells was carried out for all mem- branes using the MTT assay. Cell morphology and viability were assessed to evaluate cell attachment and pro- liferation. Regarding cell studies, the findings revealed that none of the membranes induced cytotoxic effects. However, the data showed that gold nanoparticle nanocomposite membranes improved HEK293 attachment and adhesion more than other membranes, indicating that it provides an effective surface for immobilizing cells for sensing applications.

Comparative In Vitro Osteoinductivity Study of CaP Ceramics (HA, α-TCP, β-TCP) using 10T1/2 Cells with Different Controls and Possible Correlations with Other Systems

In this study, we use a pluripotent mesenchymal stem cell (MSC) model, C3H/10T1/2, to evaluate three calcium phos-phate (CaP) materials, namely the hydroxyapatite (HA), α-tricalcium phosphate (α-TCP) and β-tricalcium phosphate (β-TCP). 10T1/2 cell was chosen as it has advantages over its counterparts in terms of ease of maintenance, free of ethical concerns and also more reproducible results. ALP enzymatic assay, RT-qPCR, DAPI staining and SEM were employed to assess the osteoinductivity of these materials. A good reference material which also acts as a scientific control is necessary for comparisons of results from different experimental batches and hence other materials such as titanium, Nunclon plastic surface, BD Falcon plastic surface and gold coated porous HA were also tested. The results show that ceramics induce a more sustained osteo-differentiation state as compared with plastics. Inductivity was found to be acting in descending order of strength with HA > β-TCP > α-TCP, which is reversed in terms of their impact on proliferation rate (HA TCP) and in vivo osteoinductivity in terms of incidence and quality of bone described previously (HA > β-TCP > α-TCP). These confirm the suitability of using 10T1/2 cells in cell culture assay of osteoinductivity.

基于金字塔池化网络的质子交换膜燃料电池气体扩散层组分推理方法

针对质子交换膜燃料电池气体扩散层(gas diffusion layer composition,GDL)形貌划分与制备工艺改进问题,提出了一种基于金字塔池化网络(pyramid scene parsing network,PSPNet)与多层感知器(multi-layer perception,MLP)的气体扩散层组分识别与比例推理方法:首先将带标签的气体扩散层扫描电镜(scanning electron microscope,SEM)图片输入神经网络,得到特征图;得到的图像特征层进入金字塔池化模块后,获取SEM图像的深层和浅层特征;随后将深层和浅层特征图层融合输入全卷积网络(fully convolutional network,FCN)模块,得到预测图像;最后统计各个组分上的像素点比例,通过MLP完成组分比例推理。结果表明:所提方法组分识别像素准确率达81.24%;在5%偏差范围内,比例推理准确率为88.89%。该方法解决了气体扩散层多组分无法区分、比例无法获知的问题,可有效应用于气体扩散层的质检、数值重构以及制备工艺改进。

体电子显微成像技术在肝癌细胞超微结构分析中的应用研究

体电子显微成像技术(volume electron microscopy)可以在更大三维空间中对样品进行纳米分辨率三维结构分析,获取样品内部结构的三维模型和各结构之间的位置关系、体积比例等信息,更加全面地反映样品的超微结构与功能的关系。本文利用基于聚焦离子束扫描电镜的体电子显微成像技术对人源肝癌细胞的三维超微结构进行分析,获得了多种细胞器包括细胞核、线粒体、内质网和高尔基体等的高分辨率三维结构模型。

Analysis of Vero cell growth behavior on microcarrier by means of environmental scanning electron microscopy

By using environmental scanning electron microscopy, the morphological changes of Vero cells attached to and grown on the microcarrier Cytodex-3 were observed, and their behavior of adhesion, spreading and proliferation was analyzed. The effect of exogenous fibronectin/ laminin on adhesion and spreading of MCC/Vero cell was studied. The images of ESEM showed that expansion of cell growth was directed toward vacancy space. The growth curve and cell concentration change during the whole culture process were obtained from the statistical counting method based on ESEM images and the crystal violet method. The growth rate of Vero cells increases with increasing the concentration of cell inoculation, that is, the specific growth rate increases quickly with increasing the concentration of cell inoculation. When serum concentration in medium #199 ranged from 5% to 10%, experimental results indicated that serum concentration is one of the important factors influencing cell growth, particularly in the cell adhesion and spreading stage.

大鼠心肌间质胶原的扫描电镜观察

目的 探讨大鼠心肌间质胶原网络的形态构筑及其功能意义。 方法 利用四氧化锇和氢氧化钠细胞浸渍方法 ,于扫描电镜下对大鼠心肌间质胶原进行观察。 结果 粗细不等的胶原纤维相互交织充填于心肌细胞及毛细血管间。粗胶原纤维平行或斜跨于细胞和血管表面 ,形成粗大的框架式结构 ;细胶原纤维卷曲蓬松 ,呈鞘状包裹心肌细胞和毛细血管 ,相邻的胶原鞘彼此融合形成间隔。 结论 心肌间质胶原网络由粗大的框架式结构和纤细的胶原网组合而成 。

兔不同血管段内皮细胞的扫描电镜观察

目的 :观察兔不同血管段内皮细胞 (EC)的形态特征 ,为兔血管的临床和实验研究提供资料。方法 :动物灌注固定 ,取出相应血管 ,扫描电镜观察。结果 :EC一般呈梭形 ,核区较隆起 ,长轴与血流的方向一致。在腹主动脉相邻细胞之间有纵行的沟 ,细胞连接处有较矮的嵴。在肺动脉有较丰富粗短的微绒毛和长短不一的桥样结构。在主动脉瓣和二尖瓣 ,细胞呈较大的圆形或椭圆形 ,微绒毛较矮 ,密度不均。在主动脉弓细胞形态多样。在下腔静脉 ,细胞呈窄长的梭形。结论 :EC的形态、排列、微绒毛的长度和密度 ,桥样结构的多少等均随部位的不同而有差异 。

bFGF基因修饰的间充质干细胞/多孔β-TCP陶瓷复合移植修复兔节段性骨缺损

目的 :探讨碱性成纤维细胞生长因子 (bFGF)基因转染间充质干细胞 (MSCs)能否构建出具有良好生物学活性的组织工程化人工骨 ,提高骨缺损修复质量。方法 :体外将具有促进MSCs增殖分化及刺激毛细血管增殖等多重生物学效应的bFGF基因转入骨组织工程首选种子细胞MSCs,并与具有良好力学强度及生物活性的可降解β磷酸三钙 (β TCP)多孔基质材料复合移植 ,修复同种异体兔桡骨 15mm长节段性骨缺损。以单纯空载体转染MSCs为对照 ,通过扫描电镜、X线、组织学及免疫组化等方法检测。结果 :转基因细胞 /基质材料体外复合培养扫描电镜观察证实bFGF基因修饰的MSCs增殖分化活性明显优于对照组。体内实验X线及组织学检测结果显示实验组骨缺损正常修复 ,有大量活跃的新骨及丰富的毛细血管生成 ;对照组各时间点则以纤维结缔组织为主 ,未见明显的新骨及血管生成。免疫组化结果显示转基因细胞可持续表达bFGF至少 4周以上。结论 :把组织工程学与分子生物学有机结合 ,使bFGF持续高效发挥作用 ,研制出具有良好生物学活性的组织工程化人工骨 ,为高质量地修复骨缺损 ,特别是治疗骨折不愈合、股骨头缺血性坏死等疾病奠定了良好的基础。

齐口裂腹鱼消化道粘膜上皮的扫描电镜观察

齐口裂腹鱼消化道粘膜上皮的扫描电镜观察方静，谢林，李逊，周毅（四川农业大学，雅安６２５０１４）关键词齐口裂腹鱼、微脊、微绒毛、杯状细胞、扫描电镜ＳＣＡＮＮＩＮＧＥＬＥＣＴＲＯＮＭＩＣＲＯＳＣＯＰＩＣＳＴＵＤＹＯＦＤＩＧＥＳＴＩＶＥＴＲＡＣＴＯＦＳＣＨ...

微气泡激发的声微流对细胞声孔效应的影响

理论及实验研究了微气泡激发的声微流对声孔效应的影响。实验采用低幅度(0.05～0.3MIPa)连续超声波信号照射MCF-7细胞,PEI:DNA的复合质粒和造影剂气泡的混合溶液,通过扫描电子显微镜测量细胞膜声孔效应。结果表明声孔大小随着激励声压的幅度和照射时间的增加而增大,平均孔径范围为100 nm～1.25μm。基于Marmottant微气泡振动模型的理论计算结果表明微气泡振动所产生的声微流引起的剪切力在低幅度超声引发声致穿孔作用中起着关键作用。

芋属5种植物叶表皮特征的扫描电镜观察

通过扫描电子显微镜观察了国产芋属(ColocasiaSchott)(天南星科Araceae)5种植物的叶表皮特征,其中花叶芋C.bicolor、异色芋C.heterochroma、李氏香芋C.lihengiae和大野芋C.gigantea4个种为首次报道.研究表明:芋属植物叶的上、下表皮细胞特征不一致,细胞为多边形,垂周壁平直或弓形,气孔器多分布于下表皮,平列型,排列无定向.气孔器类型、细胞形状及垂周壁式样等特征在种间的差异小,但与气孔外盖、气孔保卫细胞极区、表皮细胞附属物等特征结合起来分析,其结果对该属植物的分类有一定意义.

甘蓝耐裂球性与叶表面微形态及细胞组织结构的关系研究

从细胞学水平上探讨影响甘蓝裂球的原因,为甘蓝耐裂性材料的选育和新品种的育成提供理论依据,并为甘蓝耐裂性鉴定指标的制定提供依据。运用扫描电子显微镜对4份耐裂性不同的甘蓝叶表面微形态及细胞组织结构进行比较观察。结果表明:甘蓝球叶表皮细胞为无规则型,气孔为卵圆形或长椭圆形。材料间下表皮微形态存在较显著的差别:耐裂材料的垂周壁上有明显的波状嵴,平周壁上有加厚的条纹状角质层纹饰,保卫细胞四周角质层褶皱较多、起伏较大,表皮细胞上覆盖有大量的粉状或颗粒状蜡质。易裂材料的垂周壁呈沟槽状下陷,平周壁上角质层光滑,保卫细胞四周角质层较平坦。耐裂材料的叶肉细胞层数多,排列紧密,间隙小。易裂材料叶肉细胞层数少,排列松散,间隙大。耐裂材料与易裂材料在球叶表面微形态及细胞组织结构上表现显著差异。

弱酸性家蝇蛆抗菌肽MD_(7095)的分离纯化及性质研究

家蝇抗菌肽多是碱性蛋白,目前尚无弱酸性家蝇抗菌肽的报道。通过稀醋酸低温浸提,海藻酸吸附,稀盐酸低温洗脱、盐析、Sephadex G25凝胶过滤和CMC23弱阳离子交换柱层析等方法,利用灵敏的杀菌活性检测手段,从家蝇蛆(Musca domesticalarvae)中分离纯化出一组弱酸性抗菌肽,对苏云金芽孢杆菌(Bacillus thuringiensis)等革兰氏阳性菌和几种革兰氏阴性菌有强烈的杀灭作用,有极强的耐热、耐冻融的特性。通过电洗脱方法进一步纯化出抗菌肽MD7095,质谱测定其分子量7095Da,IEF电泳测得其等电点5.59,经肽质量指纹谱(PMF)鉴定为一新肽。扫描电镜超微结构观察表明,弱酸性家蝇蛆抗菌肽对苏云金芽孢杆菌的杀菌机制主要是使细胞膜穿孔,内容物外泄,最终使细菌完全解体死亡。

施万细胞对培养的神经干细胞存活及其分化的影响

目的 探讨施万细胞能否在体外促进神经干细胞的存活和分化。 方法 分离和克隆新生大鼠海马组织的神经干细胞 ;同时获取坐骨神经和臂丛神经 ,从中分离和纯化施万细胞。将施万细胞和神经干细胞进行共培养 ,借助免疫细胞化学技术检测培养的神经干细胞巢蛋白 (nestin)的表达及其分化后神经丝蛋白 (NF)和胶质原纤维酸性蛋白 (GFAP)的表达。应用扫描电镜观察神经干细胞的形态变化。 结果 与施万细胞一起培养的神经干细胞存活数量增加 ,分化为神经元样细胞的数量也明显增加。这些神经元样细胞的初级突起比对照组的明显增长。施万细胞能使神经干细胞胞体表面不规则的凹凸变得平整。共培养的施万细胞和神经干细胞可以 3种方式接触生长 :1 胞体与胞体接触 ;2 胞体与突起接触 ;3 突起与突起接触。