配置程控样品台的原子力显微镜重定位成像方法

原子力显微镜(Atomic Force Microscopy)已成为在纳米尺度对样品进行观察和操纵的重要工具。基于原子力显微镜观测的重定位技术提供一种微观区域内对样品处理前后原位对比观测的方法。本文利用坐标实时显示的程控高精度样品台系统,联合使用表面双标记定位法,建立一种新的重定位方法,方便、高效地实现样品重定位AFM成像。     

原子力显微镜在细胞生物学中应用的现状

原子力显微镜(AFM)是近十几年来表面成像技术最重要的进展之一.AFM具有原子级分辨率,它的产生和发展为细胞生物学研究提供了一种有效的工具.本文介绍原子力显微镜在细胞生物学中应用的现状,包括细胞固定,细胞成像,力检测及细胞操纵,并对原子力显微镜技术的发展进行展望.     

原子力显微镜发展近况及其应用

扫描隧道显微镜(简称STM)和原子力显微镜(简称AFM),它们也可统称为扫描探针显微镜(简称SPM)。原子力显微镜(AFM) 是近十几年来表面成像技术中最重要的进展之一。与扫描电子显微镜相比,它具有较高的分辨率。本文将讨论原子力显微镜的工作原理、原子力显微镜的发展概况和应用。     

原子力显微镜在活体微生物实时动态观测中的应用

本文运用原子力显微镜的实时成像技术,通过探索制样条件和调节仪器参数,对活体大肠杆菌进行原位实时动态观测。文中探讨研究了生理盐水、PBS磷酸缓冲液以及Tris-HCl缓冲液洗涤之后细菌的形态变化。结果表明,采用Tris-HCl缓冲液洗涤后的细菌仍然保持良好的状态,菌体饱满光滑,没有出现干瘪塌陷或是形成多细胞聚集体的现象,能够真实反映细菌的形态以及表面微结构。另外,调节原子力显微镜回馈信号的积分增益和力学参数,比较长时间实时动态观测下细菌形貌的差异,优化仪器参数设置。经过两个小时的连续观察,细菌依然保持良好的状态,菌体完整饱满,表面平整光滑,实现了活体微生物的原位实时动态观测。     

原子力显微镜控制参数对光栅清晰度的影响

原子力显微镜的发明是固体材料成像技术一次重大的飞跃,通过使用原子力显微镜对样品表面扫描成像,能够获得真实的三维图像[1],在扫描图像时需要设置好每个参数,不同的参数对原子力显微镜的成像会产生不同的影响。主要探究了积分增益以及比例增益对原子力显微镜成像光栅清晰度的影响,以图像中心距(ACM)清晰度算法和点锐度清晰度(EAV)算法作为评价的标准。实验表明,积分增益和比例增益越大,系统噪声会不断增加,相应的图像会变得越不清晰,最终保持不变。     

原子力显微镜在生物医学中的应用

原子力显微镜 (AFM)是近十几年来表面成像技术中最重要的进展之一。它具有非常高的分辨率。本文将阐述原子力显微镜的工作原理 ,分析原子力显微镜在生物医学中的应用现状 ,包括生物医学样品的表面形貌观测 ,在液体中的观测 ,生物分子之间力谱曲线的观测 ,以及生物医学样品制备技术等。     

新型电化学原子力显微镜的研制

电化学原子力显微镜将电化学分析技术与原子力显微镜结合起来,能对生物传感器,新型电池和电腐蚀进行原位电化学扫描探针显微测量分析。为了实现电化学与扫描探针功能的系统集成,在控制电路设计中采用现场可编程门阵列,提高了系统的可靠性。电化学控制箱与原子力显微镜的头部紧密集成,保证微弱信号不受干扰,并具有多种电化学工作模式。系统具有稳定性好,重复性高,抗干扰能力强等优点。     

运用碳纳米管原子力显微镜针尖减小长程力作用的研究

减小探针和样品表面之间的长程宏观力是原子力显微镜获得高分辨率成像的关键。首先通过理论分析得出影响长程力的主要因素是探针的几何形状和尺寸。然后分别运用几何形状和尺寸不同的原子力显微镜的传统Si针尖和碳纳米管针尖对样品进行扫描试验研究,结果显示碳纳米管针尖较传统针尖获得了高分辨率的图像。这一结果表明,碳纳米管针尖减小了成像中宏观长程作用力的影响,是理想的原子力显微镜针尖。     

原子力与扫描隧道组合显微镜

由大连理工大学物理系研制的原子力与扫描隧道组合显微镜 ( AF/ PSTM) ,9月 2 3日通过了国家教育部组织的鉴定。鉴定委员会对该成果给予了高度评价。该仪器是同时具有纳米分辨原子力显微镜和纳米分辨光学显微镜双重功能图像分解的纳米成像仪器。仪器技术原理是在 AF/ PSTM中设置一个双功能共振光纤尖 ,当光纤尖在样品表面近场扫描时 ,反馈控制等振幅扫描成像 ,一次扫描中 ,同时采集样品的原子力显微镜 AFM图像和光子扫描隧道显微镜PSTM图像。该仪器在分子生物学、医药学、新材料学、集成光学、纳米科技等领域均很有用 ,高校将来甚至…     

血小板制样对原子力显微镜成像技术的影响

血小板在止血、伤口愈合、炎症反应、血栓形成及器官移植排斥等生理和病理过程中有重要作用。在血小板的活化研究中,原子力显微镜可以提供确凿的形貌支持,实验中血小板制样的成功与否直接决定最后的成像。选用了云母片和硅片两种基底,采用先点样和先固定两种不同的制样方法来观察原子力显微镜成像,并总结了实验中常见的问题。成像结果显示,无论是先点样还是先固定,都可以得到很好的血小板形貌图。但在血小板的制样过程中,还有很多关键因素,如硅烷化不完整引起的溶血,动作不够轻柔引起的血小板过度活化,操作不规范引起的样品表面不平整等,在以后的实验中都应该尽量避免,更好的提供血小板研究的影像学支持。     

A multi-wall carbon nanotube (MWCNT) relocation technique for atomic force microscopy (AFM) samples

A simple relocation technique for atomic force microscopy (AFM), which takes advantage of multi-wall carbon nanotube (MWCNT), is used for investigating repeatedly the imaging of some specific species on the whole substrate with a high relocation accuracy of tens of nanometers. As an example of the application of this technique, TappingMode AFM ex situ study of the morphology transition induced by solvent treatment in a triblock copolymer thin film has been carried out.     

Hybridisation of short DNA molecules investigated with in situ atomic force microscopy

By introducing the complementary DNA (cDNA) strand to a molecular layer of short single stranded DNA (ssDNA), immobilised on a gold surface, we have investigated hybridisation between the two DNA strands through the technique of in situ atomic force microscopy (AFM). Before introduction of cDNA, the ssDNA molecular layer was modulated with the spacer molecule mercaptohexanol (MCH), which makes the ssDNA molecules more accessible for hybridisation.With in situ AFM, we have monitored the formation of a smooth, mixed molecular layer containing ssDNA and MCH. Furthermore, the hybridisation between the two DNA strands has been studied. Introduction of the cDNA strand resulted in an increase in smoothness and thickness of the molecular layer. Both the increase in order and thickness of the molecular layer can be expected if hybridisation occurs, since double stranded DNA molecules have a more rigid and elongated structure than ssDNA molecules.     

Atomic force microscopy investigation of morphological changes in living keratinocytes treated with HgCl(2) at not cytotoxic doses

Morphological changes of normal human keratinocyte cells have been monitored by means of atomic force microscopy after the exposure at a mercury solution containing HgCl(2) at 10(-7) M. The measurements have been carried out in contact mode in a thermostated liquid cell, to reproduce a cellular environment similar to the physiologic one. Remarkable alterations of the cellular morphology and volume have been revealed after few minutes from starting the exposure experiment, although the HgCl(2) concentration is several orders of magnitudes lower than the cytotoxic value (10(-4) M). The atomic force microscopy technique results to be a powerful mean to investigate modifications induced in the cell morphology by external chemical agents.     

Phase evolution in cholesterol/DPPC monolayers: atomic force microscopy and near field scanning optical microscopy studies

A combination of atomic force microscopy (AFM) and near field scanning optical microscopy has been used to study domain formation in dipalmitoylphosphatidylcholine (DPPC)/cholesterol monolayers with cholesterol concentrations ranging from 0 to 50%. The results show a clear evolution from a mixture of liquid expanded and liquid condensed phases for cholesterol concentrations < 10% to a mixture of liquid expanded and two cholesterol‐containing phases at intermediate concentrations, and finally to a single homogeneous liquid ordered phase for 33% cholesterol. Mixtures of the various phases are clearly identified by height differences in AFM and in some cases by fluorescence imaging for samples containing 0.5% BODIPY dye, which localizes preferentially in the more fluid phase. Note that fluorescence imaging, at least with the dye used here, is unable to distinguish between the cholesterol‐rich and cholesterol‐poor phases detected at intermediate cholesterol concentrations. The combination of fluorescence and AFM imaging provides a more complete picture of the phase evolution for cholesterol/DPPC monolayers than could be obtained by either technique alone, and presents substantial advantages over conventional fluorescence microscopy in that submicrometre‐sized domains can be readily detected.     

原子力显微技术在生命科学中的应用概况

从原子力显微技术自发明以来应用于生命科学领域的文章量来概述其应用和发展情况；同时，分成生物大分子、超分子聚集体和细胞三类，总结了原子力显微技术应用于生命科学的大部分研究对象，并简单介绍了其应用的发展规律。     

Experimental Study on Molecular Arrangement of Nanoscale Lubricant Films——A Review

In order to understand lubrication mechanism at the nanoscale, researchers have used many physical experimental approaches, such as surface force apparatus, atomic force microscopy and ball-on-disk tribometer. The results show that the variation rules of the friction force, film thicknessand viscosity of the lubricant at the nanoscale are different from elastohydrodynamic lubrication(EHL). It is speculated that these differences are attributed to the special arrangement of the molecules at the nanoscale. However, it is difficult to obtain the molecular orientation and distribution directly from the lubricant molecules in these experiments. In recent years, more and more attention has been paid to use new techniques to overcome the shortcomings of traditional experiments, including various spectral methods. The most representative achievements in the experimental research of molecular arrangement are reviewed in this paper: The change of film structure of a liquid crystal under confinement has been obtained using X-ray method. The molecular orientation change of lubricant films has been observed using absorption spectroscopy. Infrared spectroscopy has been used to measure the anisotropy of molecular orientation in the contact region when the lubricant film thickness is reduced to a few tens of nanometers. In situ Raman spectroscopy has been performed to measure the molecular orientation of the lubricant film semi-quantitatively. These results prove that confinement and shear in the contact region can change the arrangement of lubricant molecules. As a result, the lubrication characteristics are affected. The shortages of these works are also discussed based on practicable results. Further work is needed to separate the information of the solid-liquid interface from the bulk liquid film.     

Use of atomic force microscopy (AFM) for microfabric study of cohesive soils

Microfabric reflects the imprints of the geologic and stress history of the soil deposit, the depositional environment and weathering history. Many investigators have been concerned with the fundamental problem of how the engineering properties of clay depend on the microfabric, which can be defined as geometric arrangement of particles within the soil mass. It is believed that scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are the only techniques that can reveal particle arrangements of clayey soils directly; however, current research introduces a novel and more advanced technique, atomic force microscopy, to evaluate the microfabric of cohesive materials. The atomic force microscopy has several advantages over SEM/TEM for characterizing cohesive particles at the sub‐micrometre range by providing 3D images and 2D images with Z‐information used in quantitative measurements of soil microfabric using SPIP software, and having the capability of obtaining images in all environments (ambient air, liquids and vacuums). This paper focuses on the use of atomic force microscopy technique to quantify the microfabric of clayey soils by developing the criteria for average and maximum values of angle of particle orientation within the soil mass using proposed empirical equations for intermediate and extreme microfabrics (dispersed, flocculated).     

Atomic force microscopy imaging and 3-D reconstructions of serial thin sections of a single cell and its interior structures

The thin sectioning has been widely applied in electron microscopy (EM), and successfully used for an in situ observation of inner ultrastructure of cells. This powerful technique has recently been extended to the research field of atomic force microscopy (AFM). However, there have been no reports describing AFM imaging of serial thin sections and three-dimensional (3-D) reconstruction of cells and their inner structures. In the present study, we used AFM to scan serial thin sections approximately 60 nm thick of a mouse embryonic stem (ES) cell, and to observe the in situ inner ultrastructure including cell membrane, cytoplasm, mitochondria, nucleus membrane, and linear chromatin. The high-magnification AFM imaging of single mitochondria clearly demonstrated the outer membrane, inner boundary membrane and cristal membrane of mitochondria in the cellular compartment. Importantly, AFM imaging on six serial thin sections of a single mouse ES cell showed that mitochondria underwent sequential changes in the number, morphology and distribution. These nanoscale images allowed us to perform 3-D surface reconstruction of interested interior structures in cells. Based on the serial in situ images, 3-D models of morphological characteristics, numbers and distributions of interior structures of the single ES cells were validated and reconstructed. Our results suggest that the combined AFM and serial-thin-section technique is useful for the nanoscale imaging and 3-D reconstruction of single cells and their inner structures. This technique may facilitate studies of proliferating and differentiating stages of stem cells or somatic cells at a nanoscale.     

原子力显微镜微悬臂梁品质因数的数字调控技术的研究

为了提高轻敲模式原子力显微镜的微悬臂梁的低品质因数，在分析品质因数调控技术原理的基础上，设计了基于DSP的品质因数数字调控系统。该系统结构简单，操作方便，智能性和实时性好，能够比较精确地调控微悬臂梁振动的品质因数。通过对比液体中微悬臂梁振动的频谱以及蛋白质分子的成像实验证明，该数字调控电路能够提高微悬臂梁的力灵敏度，非常适合用于对软样品的检测。     

AFM analysis of the lacunar-canalicular network in demineralized compact bone

Atomic force microscopy has been successfully used to examine a wide range of cellular and biomolecular structures and interactions. The application of atomic force microscopy in the analysis of organs and tissues, however, has been limited. In this study, we present a new method for high-resolution atomic force microscopy imaging of compact bone tissue. We performed atomic force microscopy imaging on demineralized compact bone from bovine tibia to obtain structural information about the bone matrix and the lacunar-canalicular network. Knowledge of the dimensions and distributions of the network allows quantitative analysis of the microfluidics of bone tissue. Results from our study show that (1) the canalicular distribution and dimensions are homogenous in transverse, radial and longitudinal orientations; (2) the lamellae of an osteon consist of alternating high and low bands; (3) the canaliculi follow the contour of lamellar bands and (4) globular structures cover much of the bone matrix, including canalicular walls. Our work demonstrates that atomic force microscopy studies of thin-section tissue samples can provide structural details at nanometre resolution.