结合光学成像技术研究单颗粒碰撞电化学

近年来,单颗粒碰撞技术在纳米电化学领域受到广泛关注. 该技术通常控制超微电极处于某一电位,检测单个纳米颗粒随机碰撞到电极表面后产生的瞬时电流. 通过分析电流信号,可以研究单个纳米颗粒的性质. 尽管该技术可以检测单个纳米颗粒的电化学或电催化电流,但是传统的单颗粒碰撞技术缺乏空间分辨率,难以识别和表征特定的纳米颗粒. 因此,结合光学成像技术研究单颗粒碰撞电化学来补充电化学技术缺失的空间信息已成为一种趋势. 本文首先简要综述了单颗粒碰撞技术的三种检测原理,主要介绍了近年来单颗粒碰撞技术与荧光显微镜、表面等离激元共振显微镜、全息显微镜和电致化学发光相结合的研究进展,最后展望了单颗粒碰撞技术未来的发展趋势.     

电化学联用技术研究微生物的胞外电子传递机制

胞外电子传递（EET）是指氧化还原反应所产生的电子在微生物细胞内和细胞外的电子受体/电子供体之间互相转移的过程,这一过程伴随着能量和物质的转化。阐明EET机制是提高微生物能量和物质转化效率的基础,为元素的生物地球化学循环、金属防腐以及生物电化学系统的应用等提供理论支撑。电化学技术作为研究电极/溶液界面电子转移的简便、有效方法,在研究微生物的直接电子传递和间接电子传递机制中发挥了重要的作用,也促进了EET机制的研究从宏观层面到微观层面不断深入。本文综述了研究微生物EET机制所涉及的电化学联用技术（包括微电极、扫描电化学显微镜、电化学联用光学显微镜和光谱电化学等）;详细介绍了这些电化学联用技术的功能和优势;重点阐述了这些电化学联用技术如何推动着EET机制的研究,从宏观的生物膜层面到微观的单个微生物细胞、蛋白和分子层面不断深入;展望了新的电化学联用技术在EET研究领域的应用前景。     

《单细胞分析》

单细胞分析是分析化学、生物学和医学多学科相互渗透发展形成的跨学科前沿领域。 分析化学新方法新技术丛书——《单细胞分析》，由武汉大学程介克教授等著。全书共分15章，全面系统地介绍了单细胞分析的各种方法，包括毛细管电泳、微流控芯片、多种光学显微镜（荧光显微镜、聚焦荧光显微镜、全内反射荧光显微镜、多光子荧光显微镜、荧光相关显微镜、近场扫描光学显微镜等）、扫描电化学显微镜、质谱成像、原子力显微镜、扫描隧道显微镜图像分析、阿达玛变换显微光谱及成像、肿瘤电化学及免疫分析、动力学分析、荧光及发光探针、纳米技术以及实时动态检测等新技术和新方法。     

电化学扫描隧道显微镜的研制及银、镍的现场电沉积研究

本文报道电化学扫描隧道显微镜(ECSTM)的研制技术,包括电子线路及绝缘探针尖的制备。研制的ECSTM中,试样和探针的电位能同时控制。绝缘探针的制备包括先用电化学腐蚀形成针尖,然后再在光学显微镜下绝缘,用扫描电子显微镜评定了绝缘针尖的性能。最后用研制的ECSTM现场研究了银、镍在高定向裂解石墨(HOPG)上的电沉积。     

扫描电化学微探针的发展及其在局部腐蚀研究中的应用

简要概述当前国内外具有空间分辨能力的扫描微探针技术及其在腐蚀研究中的应用,包括扫描微电极技术(SMET)、扫描电化学显微镜(SECM)、原子力显微镜(AFM)、扫描Kelvin探针技术(SKP)等,其中SMET、SECM、SKP及局部交流阻抗技术可直接测定腐蚀电极表面或界面电化学不均一性的分布图像,而原子力显微镜技术则是通过分子间作用力从纳米尺寸测量腐蚀过程表面形貌的变化.文中侧重介绍作者近年先后建立的具有微米空间分辨度的电化学微探针技术,并利用各种扫描探针技术研究金属/溶液界面电化学不均一性及其局部腐蚀过程.研究表明,空间分辨电化学方法的发展及应用,加深了人们对金属表面和金属/溶液界面电化学不均一性,特别是金属局部腐蚀发生、发展及过程机理的认识.     

原子力显微镜及其在电化学和电分析化学中的应用

本文评述了原子力显微镜原理和技术及其在现场电化学和电分析化学领域中的应用，并展望了扫描隧道显微镜和原子力显微镜在电化学和电分析化学中的发展方向。     

原位电化学扫描探针显微镜技术在电催化领域的应用进展（英文）

在电化学界面,电催化过程通常包括电子转移、吸附和脱附、静电相互作用、溶剂化及去溶剂化等多步过程,深入理解电催化反应机理极具挑战性.对纳米结构电化学界面(电极)处电催化过程的深入理解十分有助于阐明电催化反应机理和设计高性能电催化剂材料.电催化活性通常与电催化剂表面局域化的活性位点密切有关.在反应条件下,电催化反应过程的研究极大依赖于高分辨表征技术.经典的宏观电化学表征方法仅可以提供不同界面位点的平均信息,很难分辨一些特殊结构位点(如缺陷、晶界、边缘位点)的相关重要电化学信息.原位电化学扫描探针显微镜技术,包括电化学扫描隧道显微镜(EC-STM)、电化学原子力显微镜(EC-AFM)、扫描电化学显微镜(SECM)及扫描电化学池显微镜(SECCM),能够在纳米及原子尺度研究电催化反应过程,弥补了宏观表征方法的不足,为探究构效关系和解析电催化反应机理提供了机遇.本文介绍了各种扫描显微技术的基本原理、特点及优劣势,并且概述了各项技术在电催化领域研究的重大进展.EC-STM和EC-AFM能够原位表征电催化过程中的纳米尺度表面结构演变及吸附/脱附过程,但无法直接测量局部电化学活性(法拉第电流).通过S...     

基于光学显微术的单粒子传感

基于光学显微术的单粒子传感技术是一种将光学显微镜等具有空间分辨能力的研究工具应用于分析传感领域的检测技术.该技术将单个纳米粒子视作一个完整的纳米传感器,分子识别和信号转换均在单个纳米粒子界面上完成,信号读取则通过不同种类的光学显微镜来实现.与宏观的纳米传感器相比,单粒子传感技术通过对单个纳米粒子的光学特征信号进行测量、计数和追踪,可以获得局域微区内分析物的定性和定量信息,从而具有高灵敏度、高通量和可用于微观复杂体系的动态检测等显著优点.首先简要回顾了单粒子光学传感技术的发展历史和国内外研究现状,随后介绍了其主要技术特点,并重点综述了该领域近五年内的重要研究成果.最后指出通过纳米探针、光学成像技术和多维数据处理等多方面的持续发展,可进一步提高单粒子光学传感器的性能,有望使其在分析科学、生命科学和材料科学等诸多领域获得更加广泛和深入的应用.     

扫描电化学显微镜及其在界面电化学研究中的应用

对扫描电化学显微镜(Scanning Electrochemical Microscope，SECM)的发展及其在界面电化学中的研究应用进行了评述。介绍了SECM的工作原理以及常用的操作模式，并对SECM在液／液界面、固／液界面等方面的应用进行了总结。     

电化学原子力显微镜的应用

评述了电化学原子力显微镜的原理和技术及其在现场电化学和电分析化学领域的应用,如观察电镀、腐蚀和防腐的过程,电化学沉积膜的形成和特点,测定两表面间的静电力等,指出其存在的一些缺陷,并对经过改造后的电化学原子力显微镜进行了综述。     

Correlative imaging for polymer science

The characterization of polymeric materials is key towards the understanding of structure–activity relations and therefore for the rational design of novel and improved materials for a myriad of applications. Many microscopy techniques are currently used, with electron microscopy, fluorescence microscopy, and atomic force microscopy being the most relevant. In this perspective paper, we discuss the use of correlative imaging, that is, the combination of multiple imaging methodologies on the same sample, in the field of polymeric materials. This innovative approach is emerging as a powerful tool to unveil the structure and functional properties of biological and synthetic structures. Here we discuss the possibilities of correlative imaging and highlight their potential to answer open questions in polymer science.     

Microscopic features of methacrylate polymers with zwitterionic pendant groups determined by various techniques

The objective of this work was to determine microscopic structural features of three methacrylate polymers with different numbers of diethylene glycol residues and zwitterionic pendant groups. X‐ray diffraction, electron microscopy, and scanning probe microscopy techniques were employed. X‐ray data led to the adoption of a model made up of molecular aggregates forming lamellar domains, establishing in this way ordered characteristics of these kinds of polymers. Scanning electron microscopy images provided evidence of the occurrence of a lamellar structure forming the morphology of the polymers. This was corroborated by atomic force microscopy experiments. Transmission electron microscopy revealed that the lamellar aggregates conformed into clusters immersed in a polymeric matrix. From phase‐contrast images, information on the homogeneity of the composition at a molecular surface level was obtained. Then, the techniques provided evidence of the lamellar domain characteristics of the studied sulfobetaines. The crystallinity was a function of the number of ethoxy groups because as this number increased, the crystallinity became lower © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1152–1160, 2005     

单分子定位超分辨显微成像有机荧光探针的研究进展

在生物医学领域,对纳米尺寸级别的微小生物目标进行精确定位研究具有非常重要的意义,而光学显微成像技术为此提供了强有力的工具。 光学显微成像技术受到光学衍射极限的限制,难以分辨尺寸在衍射极限(<200 nm)以下的生物结构,无法直接获取微小生物结构信息,阻碍了生物医学的进一步发展。 近年来,随着纳米分辨显微成像技术的出现,新型荧光探针的开发、成像系统与设备的不断发展及成像算法不断完善地深入结合,促进了光学衍射极限以下尺寸微观目标的研究。 基于单分子定位的超分辨荧光显微成像(SMLM)包括光激活定位成像(PALM)与随机光学重构超分辨成像(STORM),将有机荧光探针与超分辨光学显微成像技术紧密结合在一起,荧光探针的光物理性质直接决定着超分辨成像结果的好坏。 因此,设计不同性能的荧光探针可以实现超精细结构的不同超分辨成像,为研究其生物学功能提供了有力的工具。 本文着重围绕基于SMLM的原理、有机荧光探针的设计要求、用于SMLM的荧光探针种类及其生物应用等方面进行总结综述,指出了单分子定位成像上存在的不足,并对其发展方向进行了展望,希望为对超分辨成像研究感兴趣或初涉该领域的研究者提供成像理论与探针设计方面的帮助。     

In situ scanning probe microscopy and new perspectives in analytical chemistry

The resolution of scanning tunnelling microscopy (STM) and other scanning probe microscopies is unprecedented but the techniques are fraught with limitations as analytical tools. These limitations and their relationship to the physical mechanisms of image contrast are first discussed. Some new options based on in situ STM, which hold prospects for molecular- and mesoscopic-scale analytical chemistry, are then reviewed. They are illustrated by metallic electro-crystallisation and -dissolution, and in situ STM spectroscopy of large redox molecules. The biophysically oriented analytical options of in situ atomic force microscopy, and analytical chemical perspectives for the new microcantilever sensor techniques are also discussed.     

基于透射电子显微镜的沸石分子筛结构研究进展

透射电子显微镜是解析沸石分子筛新结构、 分析结构缺陷和研究活性位点等的有力工具. 应用于分子筛研究的透射电子显微术总体上可以分为图像法和衍射法, 包括透射电子显微镜和扫描透射电子显微图像、 选区电子衍射和三维电子衍射, 通常结合其中的几种方法进行分析. 近年来, 随着电子显微镜硬件性能的不断提升, 特别是球差矫正器的广泛应用及各种适用于分子筛等电子束敏感材料的探测器和图像处理技术的不断革新, 在原子尺度观察分子筛的结构已成为可能. 此外, 利用原位电子显微镜技术研究分子筛的生长和催化反应机理也在逐步展开. 本文按电子显微镜方法分类, 综述了近些年基于电子显微镜的分子筛研究, 包括新结构解析、 手性确认和金属负载等的最新进展.     

Application of multisine nanoscale impedance microscopy to heterogeneous alloy surface investigations

In the recent years atomic force microscopy is recognized as valuable tool for investigation of surficial features of construction materials. It concerns, among other things, studies of changes caused by such phenomena as galvanic corrosion, passivation associated with the growth of oxide layers, or sensitization of austenitic steels with the formation of carbide phases. In addition, atomic force microscopy allows easy coupling with impedance technique which is especially promising because of its versatility in investigations of both conductive and dielectric materials. The authors discuss the possibility of application of such type of measurement, known as impedance microscopy. Copyright © 2015 John Wiley & Sons, Ltd.     

Visualisation of electrochemical processes by coupled electrochemistry and fluorescence microscopy

The in situ coupling between electrochemistry and fluorescence microscopy is gaining popularity in the electrochemical community as a tool to image electrode processes in real time, providing useful spatial information which is not accessible by purely electrochemical methods. In recent years, new applications of electrochemical-fluorescence microscopy coupling have emerged, together with methodological developments that have expanded the possibilities of this technique. These recent trends are discussed in the present contribution, with an emphasis on the fluorogenic probes being employed.     

Friction force microscopy of self-assembled monolayers: probing molecular organisation at the nanometre scale

The basic principles behind friction force microscopy are described. Applications of friction force microscopy to self-assembled monolayers are reviewed. Work in the author’s laboratory on the frictional properties of self-assembled monolayers is described, and the findings applied in the characterisation of a much more complex material, plasma-treated polyester. Friction force microscopy is found to be a powerful tool for the analysis of the chemical composition and molecular organisation of molecular materials at the nanometre scale.     

A method for visualization of biomolecules labeled by a single quantum dot in living cells by a combination of total internal reflection fluorescence microscopy and intracellular fluorescence microscopy

We developed a simple fluorescence microscopy for acquisition of high-resolution images of single quantum dots (QDs) labeled to biomolecules on apical plasma membrane, in cell interior and on basal plasma membrane of living cells. The method was a combination of total internal reflection fluorescence microscopy (TIRFM) at apical cell surface and intracellular microscopy coupled with focusing objective. Insulin conjugated to single QD (insulin-QD) was chosen as the model system. In order to bind insulin-QDs to insulin receptors on the plasma membrane through the interaction between insulin and its receptor, as well as internalize them, the cells attached on a coverslip were incubated with biotinylated insulin and QD-streptavidin conjugate at 37 °C. Next, fluorescent molecules in the cells were photobleached by illuminating the cells using a 100-W mercury lamp with the wavelengths from 460 to 490 nm. Then, the incident angle of a laser beam was adjusted to produce total internal reflection at the apical surface of a single cell. In this case, the insulin-QDs in the whole cell were excited, and the fluorescent molecules outside the cell were not illuminated. Finally, the images of single insulin-QDs on the apical plasma membrane, in the cell interior and on the basal plasma membrane of the cell were taken by focusing the objective to different positions, respectively. The resolution and contrast of the fluorescent spots in the images were much higher than those obtained by using epi-fluorescence microscopy and comparable to those obtained by using the conventional TIRFM. The method improved the image acquisition speed for the images on the apical and basal plasma membrane using the conventional TIRFM, and could acquire the high-resolution images in the cell interior quickly.     

Simplified Near-Degenerate Four-Wave-Mixing Microscopy

Four-wave-mixing microscopy is widely researched in both biology and medicine. In this paper, we present a simplified near-degenerate four-wave-mixing microscopy (SNDFWM). An ultra-steep long-pass filter is utilized to produce an ultra-steep edge on the spectrum of a femtosecond pulse, and a super-sensitive four-wave-mixing (FWM) signal can be generated via an ultra-steep short-pass filter. Compared with the current state-of-the-art FWM microscopy, this SNDFWM microscopy has the advantages of simpler experimental apparatus, lower cost, and easier operation. We demonstrate that this SNDFWM microscopy has high sensitivity and high spatial resolution in both nanowires and biological tissues. We also show that the SNDFWM microscopy can achieve an ultra-sensitive detection based on the electron-resonance effect. This method might find an important application in tracking of nano drugs in vivo.