原子力显微镜在生物医学上的应用

原子力显微镜 (atomic force m icroscope,AFM)是扫描探针显微镜 (SPM)的一种 ,其分辨率达到纳米级 ,能对从原子到分子尺度的结构进行三维成像和测量 ,能观察任何活的生命样品及动态过程。本文概述了 AFM的基本工作原理及在生物医学上对 DNA、蛋白质、细胞及生物过程等方面进行的研究     

高精度原子力显微镜显示磁性反义探针与SK-Br-3肿瘤细胞mRNA核苷酸连接

为了将高精度原子力显微镜(AFM)用于显示超顺磁性氧化铁标记的c-erbB2癌基因反义寡脱氧核苷酸探针(磁性反义探针)与SK-Br-3肿瘤细胞mRNA核苷酸的连接,我们在磁性反义探针转染SK-Br-3肿瘤细胞基础上,用AFM对转染后的肿瘤细胞进行观察,并同时对转染后的肿瘤细胞进行蛋白表达检测及MRI成像,以进一步证实AFM的观察结果。从AFM显示的磁性反义探针转染SK-Br-3肿瘤细胞后单个细胞的全貌图及局部放大图发现,探针中反义寡脱氧核苷酸中的脱氧胞嘧啶核苷酸闭环与肿瘤细胞mRNA嘌呤核苷酸环相连接;此外,磁性反义探针能特异性抑制SK-Br3细胞c-erbB2的蛋白表达,MRI显示磁性反义探针转染SK-Br-3肿瘤细胞的信号强度最低(P<0.05)。实验表明,AFM可以清楚显示磁性反义探针与SK-Br-3肿瘤细胞核mRNA核苷酸的连接。     

CVB3病毒VP1基因及其真核表达质粒的原子力显微镜图象

原子力显微镜(AFM)是一种具有原子级分辨率的超微结构研究工具。与传统的X射线衍射、电镜等方法相比,它具有分辨率高、制样简单、可在接近生理条件下成像等优点。本研究拟用AFM观察柯萨奇B3病毒(CVB3)VP1基因及其真核表达质粒,探讨AFM在观察线性和质粒DNA中的应用。     

原子力显微镜在生物医学研究中的应用

原子力显微镜(AFM)具有纳米级成像分辨率、皮牛顿级力分辨率和可在接近生理条件下对生物样品直接表征等独特的优越性,已成为生命科学研究中的重要工具。本文主要从生物大分子成像和生物分子间相互作用力测定两个方面介绍AFM在生物医学领域中应用的新进展。     

日本科学家成功将纳米探针插入细胞，未来“细胞手术”将成为可能

日本高等工业科技研究院和东京农工大学的科学家利用附有原子力显微镜(AFM)的纳米探针观察活细胞的核子。研究人员认为，他们可以使用纳米探针用于分子传输，如：核酸、蛋白质或其他与核子有关的化学物质，甚至将来有望实施细胞手术。     

原子力显微镜在生物学中应用的现状与前景

原于力显微镜(AFM)是一种新型纳米显微技术，它拥有分辨率高、样本制作简单、成像时间短等优点，非常适合生物标本的观察。本文对原子力显微镜技术的原理进行介绍，并综述其在生物学中的应用现状及应用前景。     

关节软骨的微摩擦接触力学特性

目的使用修饰后的原子力显微镜(atomic force microscopy,AFM)探针研究关节软骨的微摩擦接触力学性能。方法使用微操作器对AFM氮化硅探针进行修饰处理,具体操作为在探针上粘贴玻璃微球作为针尖,然后使用修饰后的探针研究人体和牛关节软骨的微摩擦接触力学性能。结果人体和牛软骨的粗糙度分别为(68.63±6.22)、(50.16±6.47)nm,随着载荷的增大,人体和牛软骨的摩擦力逐渐增大。当探针滑动速度从0增加到100μm/s时,试样与探针之间的摩擦力增速很快;当速度从100μm/s增加到300μm/s时,摩擦力上升缓慢。结论软骨表面具有明显的纤维状结构,软骨的粗糙度与测量范围直接相关。随着速度或载荷的增大,人体和牛软骨的摩擦力增大,变化范围相同。探讨关节软骨在微摩擦试验中的力学和摩擦学性能表现,对于认识软骨损伤机制和医用人工关节抗磨材料的开发具有重要意义。     

简讯

日本科学家成功将纳米探针插入细胞,未来“细胞手术”将成为可能日本高等工业科技研究院和东京农工大学的科学家利用附有原子力显微镜 (AFM)的纳米探针观察活细胞的核子。研究人员认为 ,他们可以使用纳米探针用于分子传输 ,如 :核酸、蛋白质或其他与核子有关的化学物质 ,甚至将     

大鼠主动脉内皮细胞的原子力显微镜观察

血管内皮细胞具有内分泌、调节血管内外物质交换的作用[1,2]。20世纪80年代初,扫描隧道显微技术首次获得硅表面的空间形貌,随后扫描探针显微技术的各种衍生技术得到长足的发展,其中包括广泛应用于物理和化学等领域的原子力显微镜(atomic force microscope,AFM)[3]。AFM是研究生     

受弹性生物试件约束的矩形AFM悬臂梁的热响应

原子力显微术(Atomic force microscopy,AFM)是在分子与细胞水平上研究生物学问题的一个日益重要的工具。利用AFM测定生物样本的力学特性,其精度受环境热噪声的影响。我们分析了其探针受弹性生物试件(如蛋白质和DNA分子)约束的矩形AFM悬臂梁的热动力响应过程,发现该耦合系统为试件弹簧与悬臂梁弹簧的并联系统,导出悬臂梁的偏转与位移间的解析关系式,并给出考虑了窄谱效应的用于估计生物样本刚度的有理函数逼近式,从而提出一种的从AFM悬臂梁的热动力响应特征中提取生物样本刚度的新方法。     

碳纳米管原子力显微镜探针对生物样品高分辨率成像的研究

本研究将碳纳米管安装到原子力显微镜的标准硅探针上 ,制备了碳纳米管原子力显微镜针尖 ,运用其对生物样品进行高分辨率的成像研究 ,成功地获得了DNA的精细结构和G型免疫球蛋白 (Immunoglobulin G ,IgG)的Y形结构 ,这用传统的原子力显微镜针尖是无法获得的     

Atomic force microscope-based dissection of human metaphase chromosomes and high resolutional imaging by carbon nanotube tip

The present study was performed to introduce a novel chromosome dissection method employing atomic force microscopy (AFM) in a dynamic force mode for the chemical or molecular biological analysis of tiny chromosomal fragments. After AFM observation of human chromosomes prepared for light microscopy, a region of interest was dissected by increasing the loading force in a series of single-line scans of the target portion by controlling it with the amplitude reference of the tip in a dynamic force mode. The marker gene of the nucleolar organizing region (NOR) was amplified by our designed primers for 5.8S ribosomal DNA. After the dissection, topographic profiles in the section were then obtained with a carbon nanotube (CNT) probe in ambient condition. These results are discussed in relation to a fundamental technology for chromosomal analysis.     

Evanescent Electromagnetics: A Novel, Super-Resolution, and Non-Intrusive, Imaging Technique for Biological Applications

Scanning tunneling and atomic force microscopes (STM and AFM) are used to study biological materials. These methods, often capable of achieving atomic resolutions, reveal fascinating information regarding the inner workings of these materials. However, both STM and AFM require physical contact to the specimen. In the case of STM, the specimen needs to be conducting as well. Here we introduce a new method for imaging biological materials through air or a suitable liquid using decaying or evanescent fields at the tip of a properly designed microwave resonator. This novel method involves the use of an evanescent microwave probe (EMP) and is capable of imaging a variety of non-uniformities in biological materials including conductivity, permittivity, and density variations. EMP is a non-contact and non-destructive sensor and it does not require conducting specimens. Its spatial resolution is currently around 0.4 m at 1 GHz. We have used this probe to map non-uniformities in a variety of materials including metals, semiconductors, insulators, and biological and botanical samples. Here we discuss applications of EMP imaging in bone, teeth, botanical, and agricultural specimens.     

原子力显微镜在细胞生物学研究中的应用

下丘脑分泌的促甲状腺激素释放激素 (Thyrotropin- releasing hormone,TRH)促进垂体促甲状腺激素(Thyrotropin,TSH)的合成和释放 ,而多巴胺 (Dopam ine,DA)和生长抑素 (Som atostatin,SST)抑制 TSH的合成和释放 ,甲状腺激素也对 TSH产生反馈抑制作用。甲状腺功能减退患者 ,伴随多巴胺能神经元功能 (Dopam inergictone)的降低和 TSH基础水平升高。胃复安 (Metoclopramide,MCP)是多巴胺第二受体拮抗剂 ,能加速提高甲低患者血 TSH水平 ,特别是当运用于分化型甲癌 (Differentiated thyroid carcinom a,DTC)病人时 ,能缩短停用左旋甲状腺素 (L- thyroxine,L- T4 )的时间和减轻甲状腺机能减退所致的症状和体征 ,有助于对 DTC病灶的 1 31 I显像诊断和 1 31 I治疗     

原子力显微镜在细胞与生物大分子超微结构和力学研究中的应用

作为微纳米科学理论与技术迅猛发展的代表,原子力显微镜(atomic force microscopy,AFM)在其25年的发展过程中极大地推进了生物学在微纳米尺度上的拓展,为微纳米生物学的诞生与发展提供了重要技术手段。本文在介绍AFM基本原理和检测模式的基础上,结合作者在该领域的研究成果和工作经验,从生物结构与形态学研究、表面物化性质表征、生物大分子的力学操纵三方面综述了AFM在细胞与生物大分子超微结构与生物力学特性研究中的具体应用,并重点探讨了AFM在细胞与生物大分子科学研究中亟待改进和解决的科学与技术问题,提出了一些探讨性的见解和建议。     

Development of a nano manipulator based on an atomic force microscope coupled with a haptic device: a novel manipulation tool for scanning electron microscopy

We developed a novel nano manipulator based on an atomic force microscope (AFM) that can be operated inside the sample chamber of a scanning electron microscope (SEM). This AFM manipulator is also coupled with a haptic device, and the nanometer-scale movement of the AFM cantilever can be scaled up to the millimeter-scale movement of the pen handle of the haptic device. Using this AFM manipulation system, we were able to observe the AFM cantilever and samples under the SEM and obtain topographical images of the AFM under the SEM. These AFM images contained quantitative height information of the sample that is difficult to obtain from SEM images. Our system was also useful for positioning the cantilever for accurate AFM manipulation because the manipulation scene could be directly observed in real time by SEM. Coupling of the AFM manipulator with the haptic device was also useful for manipulation in the SEM since the operator can move the AFM probe freely at any position on the sample surface while feeling the interaction force between the probe and the sample surface. We tested two types of cutting methods: simple cutting and vibration cutting. Our results showed that vibration cutting with probe oscillation is very useful for the dissection of biological samples which were dried for SEM observation. Thus, cultivated HeLa cells were successfully micro-dissected by vibration cutting, and the dissection process could be observed in real time in the SEM. This AFM manipulation system is expected to serve as a powerful tool for dissecting various biological samples at the micro and nanometer-scale under SEM observation.     

Correlations between AFM and SEM imaging of acid-etched tooth enamel

Enamel bond strength is an important factor in restorative dentistry and crucially depends on the enamel roughness. To increase roughness, different etching procedures are employed and profilometric estimations, with probe profilometers, including atomic force microscopy (AFM), have been made. However, no correlation between roughness and bond strength has been found. To search for a possible error source leading to the underestimation of enamel roughness when utilizing probe profilometers, the authors compared scanning electron microscopy and AFM images of acid-etched tooth enamel. The results showed that AFM imaging cannot correctly depict the acid-etched enamel surface, because of the high steepness of the enamel crystallites and the generation of convolute images. This leads to a large underestimation of the profilometric parameters measured with AFM, or other profilometers, on acid-etched tooth enamel surfaces.     

A novel approach to AFM characterization of adhesive tooth-biomaterial interfaces.

A novel approach is proposed for studying tooth-biomaterial interactions with high resolution. Thus far, polished interfaces examined by AFM have not disclosed much detail, mainly due to the destruction of soft surface texture and the smearing of polishing debris across the interface that obscures the actual ultra-structure. Therefore the practical utility of diamond-knife microtomy as a sample preparation technique for imaging tooth-biomaterial interfaces by AFM with high resolution was tested in this study and compared to that of ultra-fine mechanical polishing techniques. The AFM images clearly demonstrated the enhanced potential of diamond-knife microtomy for nondestructively producing clean cross-sections through interfaces that allow the interfacial ultra-structure to be imaged by AFM with a resolution equaling that of TEM. This novel approach opens the field to the full range of scanning probe microscopy, including physical and chemical surface characterization of interfaces with a mix of soft and hard substrates.