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。     

原子力显微镜在生物分子力学性质方面的研究

原子力显微镜在生物纳米研究领域有广泛应用,包括对生物样品的形貌成像、超微结构、机械性能和相互作用等方面的研究。利用其非修饰和修饰探针进行样品扫描,可以得到样品表面形貌和样品表面某一特定点的力与距离的关系曲线,从而得到相关生物分子的力学性质。目前国际上应用原子力显微镜对生物分子力学特性方面的研究已经成为最热门的研究课题之一,在生物医学和临床医学方面有重要研究意义。本文简述了原子力显微镜的力曲线原理,并对近年来应用原子力显微镜在探测生物分子力学性质方面的研究进展进行了综述。     

原子力显微镜在聚合物研究中的应用

原子力显微镜以其分辨率高、样品无需特殊制备、实验可在大气环境中进行等优点而广泛应用于聚合物研究之中,弥补扫描隧道显微镜不能观测非导电样品的缺憾。近年来,其应用已由对聚合物表面几何形貌的观测发展到纳米级结构和表面性能的研究领域。在介绍原子力显微镜工作原理的基础上,简要回顾其在聚合物研究方面的若干新应用,并对其应用前景作展望。     

超微生物力学测量中的原子力显微镜技术

原子力显微镜不仅可以在分子水平上对作用力进行测量,得到表面形状的图像,而且也可以用于高分子的解旋和空间构象的研究,此外也可研究样品表面的其他物理特性如压弹性、粘弹性特性的研究.文章首先阐明了微观力学表征的生物学意义,接着强调了原子力显微镜探针与样品间相互作用的类型及其在生物力学量测量中的原理和过程,之后分别介绍了原子力显微镜在细胞间黏附力、生物分子间相互作用、单分子力谱等方面的应用成果,最后结合原子力显微镜的应用现状对微观生物力的原子力显微镜深入研究进行了展望.     

生物大分子超微结构研究中的原子力显微术

原子力显微镜作为第三代显微探测工具,具有原子级的空间分辨率,其样品制备方法简单易行,可在离体的近生理条件下直接观测生物样品及其动态变化过程,能够对样品进行力学操纵,在观察生物大分子的结构和生物力学特性上具有显著的优势。本文尝试从蛋白质、核酸、多糖的超微结构和力学特性的研究角度入手,期望向读者展现出原子力显微镜在大分子生物学研究中的应用前景。     

生物分子LB膜表面结构与物化性质的原子力显微镜分析

LB膜以其广泛的应用价值而备受关注,而其各种性质的表征是推动其应用的源动力,原子力显微镜以其优秀的时空分辨能力、力学操纵能力而在众多表面表征技术中显得尤为突出。文章在详细介绍原子力显微镜基本探测原理的基础上,全面总结了原子力显微镜技术在LB膜参量,如表面精细结构、静电荷分布、磁畴分布、膜分子间相互作用等分析中的应用,并探讨了该技术在膜表面表征中存在的技术问题,对膜参量表征技术的发展和应用前景进行了展望。     

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…     

扫描探针显微镜在粗糙度、纳米尺寸、表面形貌观测方面的应用

扫描探针显微镜是近十几年来在表面特征表面形貌观测方面最重大的进展之一，是纳米测量学的基本工具，本文叙述了扫描探针显微镜的工作原理、检测模式及在观察检测纳米级的粗糙度、微小尺寸、表面形貌方面的特点和方法，比较了原子力显微镜、常规的表面轮廓仪、干涉显微镜、扫描电子显微镜在表面特性、表面形貌观测方面的性能，着重介绍了扫描探针显微镜在这方面的应用和存在的问题。     

原子力显微镜探针对环型DNA分子的切割研究

本文利用原子力显微镜氮化硅探针对吸附在云母基底表面上的超螺旋环形pCI-neo质粒DNA成功地进行了切割操作,同时计算出探针的切割力约为40nN。同时对切割的精度和切割后样品的拾取等问题进行了深入地的分析和探讨。原子力显微镜用于生物样品的纳米级操纵对生物样品的研究具有重要的研究价值。     

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。     

Nanostructural analysis by atomic force microscopy followed by light microscopy on the same archival slide

Integrated information on ultrastructural surface texture and chemistry increasingly plays a role in the biomedical sciences. Light microscopy provides access to biochemical data by the application of dyes. Ultrastructural representation of the surface structure of tissues, cells, or macromolecules can be obtained by scanning electron microscopy (SEM). However, SEM often requires gold or coal coating of biological samples, which makes a combined examination by light microscopy and SEM difficult. Conventional histochemical staining methods are not easily applicable to biological material subsequent to such treatment. Atomic force microscopy (AFM) gives access to surface textures down to ultrastructural dimensions without previous coating of the sample. A combination of AFM with conventional histochemical staining protocols for light microscopy on a single slide is therefore presented. Unstained cores were examined using AFM (tapping mode) and subsequently stained histochemically. The images obtained by AFM were compared with the results of histochemistry. AFM technology did not interfere with any of the histochemical staining protocols. Ultrastructurally analyzed regions could be identified in light microscopy and histochemical properties of ultrastructurally determined regions could be seen. AFM-generated ultrastructural information with subsequent staining gives way to novel findings in the biomedical sciences. Microsc. Res. Tech., 2009. © 2009 Wiley-Liss, Inc.     

Atomic force microscopy wear characterization of biomedical polymer coatings

Atomic force microscopy (AFM) has become established as a powerful and versatile tool for investigating local mechanical properties. In addition, through the AFM tip–sample interaction, it has become possible to study the effects of perturbations and modifications to the surface of soft samples, such as polymers. The accurate knowledge of their response to continuous AFM scanning could help to design new materials having desirable mechanical properties. In this paper, we present the results obtained by applying a new methodology to investigate wear properties on two different type of polymer, poly(methyl‐methacrylate) and poly(l ‐lactic acid). These polymers have been widely employed in biomedical applications and have recently been considered as good candidates for coronary metallic stent coatings. Copyright © 2006 John Wiley & Sons, Ltd.     

Atomic force microscopy imaging of living cells: a preliminary study of the disruptive effect of the cantilever tip on cell morphology

Recent studies have demonstrated that atomic force microscopy (AFM) is a potential tool for studying important dynamic cellular processes in real time. However, the interactions between the cantilever tip and the cell surface are not well understood, and the disruptive effect of the cantilever tip on cell morphology has not been well characterized. In this study, the disruptive effect of the scanning cantilever tip on cell morphology, in the AFM contact mode, has been investigated. The aims of this study are to identify what kinds of cell morphological changes generally occurred under normal AFM imaging conditions and to find out how long cells remain viable during scanning. Two cell lines, SK-N-SH (human neuroblastoma cells) and AV12 (Syrian hamster cells) were studied in the experiment because these are widely used in biomedical research as an expression system for studying cellular functions of neuronal receptors. The experimental results suggest that the sensitivity of cells to the cantilever disruptive effect is dependent on cell type and that there are patterns observed in the changes of cell morphology induced by the cantilever force in these two cell lines.     

Comparison of the indentation and elasticity of E. coli and its spheroplasts by AFM

Atomic force microscopy (AFM) provides a unique opportunity to study live individual bacteria at the nanometer scale. In addition to providing accurate morphological information, AFM can be exploited to investigate membrane protein localization and molecular interactions on the surface of living cells. A prerequisite for these studies is the development of robust procedures for sample preparation. While such procedures are established for intact bacteria, they are only beginning to emerge for bacterial spheroplasts. Spheroplasts are useful research models for studying mechanosensitive ion channels, membrane transport, lipopolysaccharide translocation, solute uptake, and the effects of antimicrobial agents on membranes. Furthermore, given the similarities between spheroplasts and cell wall-deficient (CWD) forms of pathogenic bacteria, spheroplast research could be relevant in biomedical research. In this paper, a new technique for immobilizing spheroplasts on mica pretreated with aminopropyltriethoxysilane (APTES) and glutaraldehyde is described. Using this mounting technique, the indentation and cell elasticity of glutaraldehyde-fixed and untreated spheroplasts of E. coli in liquid were measured. These values are compared to those of intact E. coli. Untreated spheroplasts were found to be much softer than the intact cells and the silicon nitride cantilevers used in this study.     

Atomic force microscopy of histological sections using a new electron beam etching method

In order to examine histological sections of the rat vomeronasal epithelium with the atomic force microscope (AFM), we developed an electron beam etching method that improves the resolution of AFM images. This method results in AFM images comparable to those obtained with the transmission electron microscope (TEM). Ultrathin tissue sections embedded in epoxy resin were observed before and after the treatment with electron beam radiation. Before electron beam treatment, epithelial structures such as the microvilli surface, dendritic processes, the supporting cell layers and the neuronal cell layers were all visible using the AFM. However, only a few subcellular structures could also be resolved. The AFM images were not as clear as those obtained with the TEM. After electron beam treatment, however, the resolution of AFM images was greatly improved. Most of the subcellular structures observed in TEM images, including the inner membrane of mitochondria, ciliary-structure precursor body, junctional complexes between the neurons and supporting cells, and individual microvilli were now visible in the AFM images. The electron beam treatment appeared to melt the embedding resin, bringing subcellular structures into high relief. The result of this study suggests that electron beam etching of histological samples may provide a new method for the study of subcellular structure using the AFM.     

Atomic force microscopy of freeze-fracture replicas of rat atrial tissue

Atomic force microscopy (AFM) has provided three-dimensional (3-D) surface images of many biological specimens at molecular resolution. In the absence of spectroscopic capability for AFM, it is often difficult to distinguish individual components if the specimen contains a population of mixed structures such as in a cellular membrane. In an effort to understand the AFM images better, a correlative study between AFM and the well-established technique of transmission electron microscopy (TEM) was performed. Freeze-fractured replicas of adult rat atrial tissue were examined by both TEM and AFM. The same replicas were analysed and the same details were identified, which allowed a critical comparison of surface topography by both techniques. AFM images of large-scale subcellular structures (nuclei, mitochondria, granules) correlated well with TEM images. AFM images of smaller features and surface textures appeared somewhat different from the TEM images. This presumably reflects the difference in the surface sensitivity of AFM versus TEM, as well as the nature of images in AFM (3-D surface contour) and TEM (2-D projection). AFM images also provided new information about the replica itself. Unlike TEM, it was possible to examine both sides of the replica with AFM; the resolution on one side was significantly greater compared with the other side. It was also possible to obtain quantitative height information which is not readily available with TEM.     

3-D morphological characterization of the liver parenchyma by atomic force microscopy and by scanning electron microscopy

A comparative study of atomic force microscopy (AFM) and scanning electron microscopy (SEM) imaging of the healthy human liver parenchyma was carried out to determine the similarities and the differences. In this study, we compared the fine hepatic structures as observed by SEM and AFM. Although AFM revealed such typical hepatic structures as bile canaliculi and hepatocytes, it also showed the location of the nucleus and chromatin granules in rough relief structure, which was not visible by SEM. By contrast, SEM visualized other structures, such as microvilli, the central vein, and collagenous fibers, none of which was visualized by AFM. For better orientation and confirmation of most of the structures imaged by SEM and AFM, Congo Red-stained specimens were also examined. Amyloid deposits in the Disse's spaces were shown especially clearly in these images. The differences between the SEM and AFM images reflected the characteristics of the detection systems and methods used for sample preparation. Our results reveal that more detailed information on hepatic morphology is obtained by exploiting the advantages of both SEM and AFM.     

Using the atomic force microscope to observe and study the ultrastructure of the living BIU-87 cells of the human bladder cancer

In this study, the ultrastructure of living BIU-87 cells of human bladder cancer was mapped using atomic force microscopy to reveal the dynamic change of single cancerous cell division. Simultaneously, the feasibility and functional reliability of the atomic force microscope (AFM) were established and a laboratory model using AFM to study living cancerous cells was created. In this experiment, BIU-87 cells of human bladder cancer were cultured by conventional methods and grown in gelatin-treated dishes. A thermostat was used for preserving the cell's living temperature. Scanning of these cells using AFM was carried out in physiologic condition. The AFM images of the ultrastructure of living BIU-87 cells as well as those of the cell's membrane and cytoskeleton were very clear. The dynamic phenomenon of single cell division was observed. It was concluded that the AFM was able to observe and depict the ultrastructure of living cells of human bladder cancer directly and in real time. This experimental model is expected to play an important role in elucidating the cancerous mechanism of bladder normal cells at the atomic or nanometer level.     

The immobilization of animal cells using the cysteine-modified RGD oligopeptide

RGD peptide sequence is an effective cell recognition motif and used to enhance the cell adhesion on desired solid material for cell immobilization. We have synthesized CRGD, CRGD-multiple-armed peptide (MAP), RGD-MAP-C and evaluated their comparative efficacy for cell immobilization. Each peptide was assembled on gold surface and investigated by the atomic force microscopy (AFM) technique in the contact mode. The viability of immobilized animal cells was examined by an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Our results showed that RGD-MAP-C in comparison to others was the most effective proliferation of cells on the gold surface. The goal of this present work is integration to the nano-pattern cell chip bioplatform for biomedical assays or provide valuable insights into cell biology and design of biomaterials. This RGD-MAP-C can be applicable to the nano-pattern cell chip platform.     

原子力显微镜在DNA领域中研究应用

原子力显微镜(AFM)是研究DNA有力工具,在对DNA研究中有其独特优势。本文概述原子力显微镜DNA研究中应用以及取得进展。虽然原子力显微镜在研究DNA研究中仍有局限性,但随着原子力显微技术及相关技术发展,原子力显微镜在DNA中研究必将不断深入。