光学椭偏成像技术在生物分子研究中的应用

光学椭偏显微成像是一种新型超薄膜及表面显示技术,是研究生物分子与固体表面吸附以及生物分子之间相互作用的一种简单、快速和可靠的手段。它不仅能够大面积精确显示超薄膜的厚度分布,而且能够用于表面实时吸附的动力学研究。在抗原抗体检测分析方面,它不需要像酶联免疫法、荧光免疫法和放射免疫法那样对待测物作标记,也不会对待测生物分子活性造成任何扰动和损伤,操作简单,费用低廉。另外,它还弥补了传统的椭偏法的不足之处,能够有效地区分非特异性吸附、脱吸附或表面污染带来的干扰。     

亲和素蛋白与含有生物素的支撑平面膜之间相互作用的研究

生物功能分子的二维有序化组装是分子工程学的重要内容。本文通过构建有生物素受体的人工模型膜,对亲和素与生物素这一具有极强亲和力的系统之间的特异性相互作用的某些制约因素进行了探讨．应用ＬＢ膜技术结合激先椭圆偏振术和表面等离激元谱技术,较深入地研究了蛋白质与脂单层膜发生的非特异性吸附,特异性结合以及结合的侧向空间位阻效应．实验结果表明,膜表面电荷对非特异性吸附的速率有很大的影响,而对最终的蛋白吸附量影响不大;非特异性的吸附可以通过二阶阳离子的脱附而去除;受体蛋白质与配体间的特异性结合受到侧向空间位阻效应的制约．     

亲和素蛋白与含有生物素的支撑平面膜之间相互作用的研究

生物功能分子的二维有序化组装是分子工程学的重要内容,本文通过构建有生物素受体的人工模型膜,对亲和素与生物这一具有极强亲和力的系统之间的特异性相互作用的某些制约因素进行了探讨,应用ＬＢ膜技术结合激光椭圆偏振术和表面等离激元谱技术,较深入地研究了蛋白质与脂单层膜发发的非特异性吸附,特异性结合以及结合的侧向空间位阻效应,实验结果表明,膜表面电荷对非特异性吸附的速率有很大的影响,而对最终的蛋白质附量影响不     

原位椭圆偏振术研究牛血清清蛋白在固/液界面的吸附

用原位椭圆偏振术系统研究了硅片表面因素及缓冲液环境因素对牛血清清蛋白在固/液界面吸附的影响。在生理条件下,疏水表面与亲水表面相比BSA吸附量较大。随着硅片表面电荷密度增加,BSA吸附量增加。BSA吸附量当体溶液pH值等于BSA等电点时达到最大。而随着体溶液离子强度增加,BSA吸附量亦上升。实验结果提示:除了熵驱动作用之外,硅片表面与BSA分子及BSA分子之间的静电作用在BSA吸附中起着十分重要的作用。     

纳米狭缝中Aβ蛋白构象变化的间距作用

目的 金属表面对蛋白质分子具有吸附作用,然而在纳米尺度内,蛋白质分子构象受到狭缝的间距作用尚未明确。本文通过在分子动力学模拟中建立不同间距的金原子层,研究纳米级金属狭缝中蛋白质分子构象变化。方法 使用GOIPCHARMM力场在Au (111)金原子界面间对Aβ1-42蛋白单体进行分子动力学仿真,研究无狭缝的水溶液环境下和由5.0、5.5以及8.5 nm狭缝结构与Aβ蛋白相互作用及蛋白质构象变化。结果 当金狭缝结构间距从5.0 nm增加到8.5 nm,Aβ蛋白分子与两侧金层相互作用可由单表面吸附、双表面吸附过渡到无吸附。结论 Aβ蛋白分子在金狭缝结构中与表面发生相互作用,随狭缝间距和蛋白质分子距界面距离的变化,蛋白质分子的状态可能表现为单表面吸附、双表面吸附和无吸附3种状态。     

非线性模型在蛋白质薄膜厚度测定中的应用

分子通过测定蛋白质薄膜厚度变化而定量地研究生物分子间的相互作用,探讨了基于光学干涉光的薄膜厚度的测量方法,借助于在玻璃基底表面沉积的聚苯乙烯薄膜对噪声的抑制,使用非线性回归模型对生物传感器的检测信号进行了分析。通过反射干涉光谱光测定到乙型肝炎表面抗原在聚苯乙烯－玻璃表面的吸附使薄膜厚度增加了３．３ｎｍ。随着５μｇ／ｍｌ,１０μｇ／ｍｌ,２０μｇ／ｍｌ,３０μｇ／ｍｌ和５０μｇ／ｍｌ浓度的乙型肝炎表     

红外衰减全反射光谱及其在生物学中的应用

本文介绍了红外衰减全反射光谱(IR-ATR)的基本原理及其在生物学领域内的广泛应用。文中列举了ATR技术对生物分子的组成、形态、表面结构以及表面吸附的定性和定量研究的例子。     

疏水表面对牛血清清蛋白二级结构的诱导

本文结合圆二色谱,椭圆偏振术及放射性示踪技术研究了疏水表面对牛血清清蛋白二级结构的诱导作用,实验结果表明：处于不同阶段的蛋白质分子由于受到不同程度的诱导作用而呈现不同的二级结构特征。初始阶段吸附的ＢＳＡ分子丧失有序结构,形成以无规卷曲为主的二级结构。中间阶段吸附的ＢＳＡ呈现出以β结构为主的二级结构。而后期吸附的ＢＳＡ分子保存了大部分α螺旋结构。作者认为疏水表面对ＢＳＡ二级结构的诱导与表面的疏水作用     

土壤矿物与微生物相互作用的机理及其环境效应

土壤矿物与微生物相互作用是地球表层系统中重要的生态过程.微生物或生物分子与矿物间的吸附(粘附)是两者相互作用的基础.吸附(粘附)是一个由分子间力、静电力、疏水作用力、氢键和空间位阻效应等多种作用力或作用因素共同决定、影响的物理化学过程.因此,微生物和矿物的表面性质如表面电荷、疏水性和它们所处的环境条件如pH、电解质浓度、温度等,都影响着矿物-微生物吸附(粘附)过程.微生物细胞或酶可吸附于矿物表面,其结果是细胞代谢或酶活性会发生明显变化,并进一步影响土壤中诸多相关的生态、环境过程.结合4种典型的初始吸附理论:表面自由能热力学理论、DLVO理论、吸附等温线理论和表面复合物理论及本课题组近年来的研究成果,对土壤矿物与微生物相互作用的类型、机理、作用力和现代研究技术等方面的最新研究进展进行了较为全面的论述,对土壤矿物-微生物相互作用的环境效应进行了讨论,并就该领域今后研究工作的特点及应关注的问题进行了展望.     

浅谈菌丝体表面分子印迹吸附剂的选择性吸附

通过制备的方法获得菌丝体表面分子印迹吸附剂,本文系统的分析和探讨了针对模板金属离子菌丝体表面分子印迹吸附剂的吸附选择性。通过实验研究证明,菌丝体表面分子印迹吸附剂如果是以Ni2+为模板制备的,相对于非印迹吸附剂来讲,其对Cr3+、Cu2+、Ni2+的吸附容量以及吸附速率的提高幅度都是非常大的。而菌丝体表面分子印迹吸附剂相对于具有Ni2+金属离子混合溶液来讲,其对Ni2+的选择性以及吸附容量要比含有诸如Cu2+以及Cr3+的金属离子提高的都要明显很多;印迹吸附剂相对于非印迹吸附剂来讲,其在吸附非模板金属离子Cu2+以及Cr3+时具有明显降低的选择性。     

Influence of interfaces on microbial activity.

Bacterial adhesion in natural and artificial systems has been critically reviewed to investigate the influences exerted by the presence of interfaces. Numerous investigations have demonstrated that, in the presence of a solid phase, the activity of bacterial cultures is changed. Reviewing relevant literature, two problems were encountered. One is of an experimental nature. Due to lack of similarity in experimental conditions, disparate experiments often cannot be compared; their results may even appear conflicting. The other problem is of an interpretational nature: several hypothetical theories exist which try to explain the effect of surfaces on microbial activity. These theories often confuse changes in the medium and limitations in mass transfer which are due to the presence of solid surfaces (indirect influences) with changes in cell properties (direct influences). Whenever a surface is reported to influence the metabolism of bacteria, the action is found almost exclusively to be due to changes in the medium or environment and is therefore indirect. Based on data reported in the literature, and by using thermodynamic and kinetic considerations, it is concluded that so far neither experimental nor theoretical evidence exists for a direct influence of interfaces on microbial activity.     

A method for selective isolation and aggregation of epicuticular wax nanotubes in Picea pungens

A method for selectively isolating and aggregating intact nanotubes from leaf surfaces, in sample quantities useable for their characterisation in further experimental investigations, is presented here. It uses liquid sucrose, as a saturated solution, with its wetting behaviour modified by the addition of controlled amounts of ethanol, as a temporary entrapment and release medium, for removing nanotube material from the leaf surface, here of Picea pungens (Engelmann). This harvesting technique works by the slow, gentle transition of the medium from liquid to solid, capturing the nanotubes, and then back to liquid again, releasing them, to form an aggregate sample, with little compromise to the structural integrity of individual nanotubes. Scanning electron microscopy (SEM) images are presented rigorously illustrating the technique and its effectiveness. Comparison with other recent methods reveals its advantages, and potential applications are explored.     

Electrokinetic determinations of enzymatic susceptibilities of cell surface-associated RNA

Earlier investigations suggested, using electrokinetic evidence, that RNA is present at the surfaces of some types of cultured and freshly isolated cells. In this report, further investigations of the nature of cell surface RNA of cultured Ehrlich ascites (EAT) cells are reported. These experiments were carried out by determining the changes in electrophoretic mobility of EAT cells after treatment with several highly purified nucleases, neuraminidase, and hyaluronidase. The results suggested that cell surface RNA is located at surface sites separate from those susceptible to neuraminidase and hyaluronidase, that alpha and omega termini of RNA are absent from the electrokinetic surface, and that the RNA present at the cell surface might exist predominantly in a double-stranded form. A model is proposed in which cell surface RNA strand termini are buried out of the electrokinetic surface, but where RNA extends from these buried termini into the electrokinetic surface in loops.     

Electrokinetic determinations of enzymatic susceptibilities of cell surface-associated RNA

Earlier investigations suggested, using electrokinetic evidence, that RNA is present at the surfaces of some types of cultured and freshly isolated cells. In this report, further investigations of the nature of cell surface RNA of cultured Ehrlich ascites (EAT) cells are reported. These experiments were carried out by determining the changes in electrophoretic mobility of EAT cells after treatment with several highly purified nucleases, neuraminidase, and hyaluronidase. The results suggested that cell surface RNA is located at surface sites separate from those susceptible to neuraminidase and hyaluronidase, that α and ω termini of RNA are absent from the electrokinetic surface, and that the RNA present at the cell surface might exist predominantly in a double-stranded form. A model is proposed in which cell surface RNA strand termini are buried out of the electrokinetic surface, but where RNA extends from these buried termini into the electrokinetic surface in loops.     

Conformational chemistry of surface-attached calmodulin detected by acoustic shear wave propagation

A thickness shear-mode acoustic wave device, operated in a flow-through format, was used to detect the binding of ions or peptides to surface-attached calmodulin. On-line surface attachment of the protein was achieved by immobilisation of the biotinylated molecule via a neutravidin-biotin linkage onto the surface of the gold electrode of the detector. The interaction between calmodulin, and calcium and magnesium ions induced an increase in resonant frequency and a decrease in motional resistance, which were reversible on washing with buffer. Interestingly, the changes in resonant frequency and motional resistance induced by the binding were opposite to the normal operation of the detector. The response was interpreted as a decrease in surface coupling (partial slip at the liquid/solid interface) instigated by exposure of hydrophobic domains on the protein, and an increase in the thickness, and hence effective wavelength, of the acoustic device, corresponding to an increase in the length of calmodulin by 1.5 A. This result is consistent with the literature value of 4 A. In addition, the interaction of the protein with peptide together with calcium ions was detected successfully, despite the relatively low molecular mass of the 2-kDa peptide. These results confirm the potential of acoustic wave physics for the detection of changes in the conformational chemistry of monolayer of biochemical macromolecules at the solid/liquid interface.     

Hydrolysis of supported pyrenephospholipid monolayers by phospholipase A2

Hydrolysis by pancreatic and snake venom (Crotalus atrox) phospholipase A2 of fluorescent monolayers of pyrene-labelled phosphatidylglycerol on solid support was studied. We used a fluorescence microscope equipped with video camera, video recorder and an image analyzer to monitor changes in fluorescence. Decrease in pyrene excimer emission was evident when pyrene phosphatidylglycerol monolayers transferred onto quartz glass slides (at a surface pressure of 15 mN m-1) were subjected to enzymatic hydrolysis. Snake venom phospholipase A2 could hydrolyze the monolayers almost completely while pancreatic phospholipase A2 could cause only 50% decrease in fluorescence intensity. EDTA totally inhibited the action of both A2 phospholipases. When monolayers were transferred onto solid supports at a surface pressure of 31 mN m-1 C. atrox phospholipase A2 could still exert activity whereas porcine pancreatic phospholipase A2 was inactive.     

Lateral Flagella and Swarming Motility in Aeromonas Species

Swarming motility, a flagellum-dependent behavior that allows bacteria to move over solid surfaces, has been implicated in biofilm formation and bacterial virulence. In this study, light and electron microscopic analyses and genetic and functional investigations have shown that at least 50% of Aeromonas isolates from the species most commonly associated with diarrheal illness produce lateral flagella which mediate swarming motility. Aeromonas lateral flagella were optimally produced when bacteria were grown on solid medium for approximately 8 h. Transmission and thin-section electron microscopy confirmed that these flagella do not possess a sheath structure. Southern analysis of Aeromonas reference strains and strains of mesophilic species (n = 84, varied sources and geographic regions) with a probe designed to detect lateral flagellin genes (lafA1 and lafA2) showed there was no marked species association of laf distribution. Approximately 50% of these strains hybridized strongly with the probe, in good agreement with the expression studies. We established a reproducible swarming assay (0.5% Eiken agar in Difco broth, 30 degrees C) for Aeromonas spp. The laf-positive strains exhibited vigorous swarming motility, whereas laf-negative strains grew but showed no movement from the inoculation site. Light and scanning electron microscopic investigations revealed that lateral flagella formed bacterium-bacterium linkages on the agar surface. Strains of an Aeromonas caviae isolate in which lateral flagellum expression was abrogated by specific mutations in flagellar genes did not swarm, proving conclusively that lateral flagella are required for the surface movement. Whether lateral flagella and swarming motility contribute to Aeromonas intestinal colonization and virulence remains to be determined.     

Responses of Marine Bacteria Under Starvation Conditions at a Solid-Water Interface

Size changes during starvation of 17 marine bacterial isolates at a solid-water interface and in the liquid phase were examined. Twelve rod-shaped, hydrophilic bacteria decreased in size more rapidly at the solid surface than in the liquid phase, a result parallel to that observed previously for one of the strains at an air-water interface. On the other hand, three rod-shaped, hydrophobic bacteria diminished in size more rapidly in the liquid phase than at the solid-water interface. The rapid size decrease (defined here as the dwarfing phase) in either situation appeared to be an active process which occurred more rapidly when the cells were in an early stage of logarithmic growth at the onset of starvation. Dwarfing was reversibly inhibited by low temperature and low pH but was not inhibited by chloramphenicol. Three coccoidal bacteria showed little tendency to become smaller upon starvation in the liquid phase or at a surface.     

CAR-T cell therapy and its application in clinical cancer treatment

Immunotherapy is regarded as the most significant method for cancer treatment in recent years. Chimeric antigen receptor T cells (CAR-T) technology, one form of target immunotherapy, has made a great breakthrough in hematological malignancies treatment and also a few progress in solid tumor treatment. This article reviews the history and mechanism of CAR-T, as well as the advantages and limitations of CAR-T in clinical cancer treatment. Then the review mainly discussed the clinical trial progress of CAR-T cell therapy in solid tumor treatment. A primary obstacle of CAR-T therapy is the heterogeneity in solid tumors. With an increasing number of solid tumor surface antigens being discovered, different varieties of CARs have been designed to treat solid tumors and have made some progress in clinical trial. In the end, this review puts forward a possible development direction of CAR-T.     

Ultrasound-assisted lipectomy using the solid probe: a retrospective review of 100 consecutive cases

Ultrasound-assisted lipectomy using the solid probe is a predictable and safe method that can yield excellent results. This method is particularly useful and is indicated when the subdermis must be approached to smooth out surface irregularities and/or to stimulate skin retraction. The authors present their method using the solid probe and a retrospective study of their first 100 consecutive cases. The indications for using the solid probe, its advantages and disadvantages, associated complications, and representative cases are presented.