Development and Application of Atomic Force Microscopy to biological sciences.

原子力显微镜(AFM)(JSTM-4200A，JEOL)是扫描探针显微镜的一个亚型，用于开发生物应用技术。原子力显微镜配备了接触式装置，在室温下，悬臂梁尖端的氮化硅探头在空气中扫描试件表面。由于AFM最初是为材料科学而设计的，为了获得更好的生物材料可获得性，对一些部件或装置进行了改进。还开发了新的生物标本制备方法，并尝试在AFM下进行观察。将重新悬浮在双蒸水中的纯化的质粒DNA结合在新裂解的云母表面，并在AFM下显示出DNA分子的圆形轮廓。尽管测量的约10 nm的厚度不被认为是正确的顺序，但这种方法的可及性将有助于分子相互作用的分析。对某些类型的上皮细胞表面的观察显示，空气中高倍率的微绒毛和微绒毛清晰可见，没有扫描电子显微镜观察所需的金属涂层。冷冻干燥是制备样品的有效方法，与常规显微镜相比，AFM的优点是在空气中观察分辨率高，易于操作，即使在潮湿条件下也可以操作，在潮湿条件下，分子和细胞保持着比干燥条件下更多的功能结构。原子力显微镜将为生物材料的观察提供一种新的有用的方法。

The atomic force microscope (AFM) (JSTM-4200A,JEOL), one of subtypes of scanning probe microscopes, was introduced to develop techniques for biological applications. The AFM is equipped with contact mode device in which a silicon-nitride probe at the tip of cantilever scan over the surface of specimens in the air at room temperature. As the AFM is originally designed for material sciences, some parts or devices were modified in order to obtain better accessibility for biological materials.New preparation procedures of biological specimens were also developed and attempted for observation under AFM.Purified plasmid DNA resuspended in double distillled water were bound on the freshly cleaved mica surface, and a circular profile of DNA molecules was visualized under AFM.Although the thickness measured about 10 nm is not considered to be correct order, the accessibility of this method will be facilitated for analysis of molecular interactions. Observation of some types of epithelial cell surface revealed clear images of microvilli and microplicae with high magnification in the air, without metal coating which is required for SEM observation. Freeze-drying is proved to be effective for preparation of specimens.The advantages of AFM over conventional microscopy are observation of high resolution in the air, easy accessibility, and to be operable even in wet condition in which moleculea and cell maintain more functional structure than in dry condition. The AFM will provide a new useful method for the observation of biological materials.