Atomic force microscopy and its related techniques in biomedicine.

The atomic force microscope (AFM), invented in 1986, is a new instrument which provides three-dimensional surface images of samples by scanning a sharp probing tip over the sample surface. Unlike electron microscopes (EM), the AFM has the advantage to obtain high-resolution pictures not only in a vacuous but also in a non-vacuous (i.e., air or liquid) environment. This paper reviews our recent studies on the AFM application to the biomedical fields. AFM is useful for observing biological structures such as DNA, collagen molecules, collagen fibrils and chromosomes. AFM images of living cultured cells in liquid can be used for investigating the movement of cellular processes in relation to subcellular cytoskeletal elements. Recently, numerous AFM-related microscopes, or scanning probe microscopes (SPM), have been invented in parallel with the development of the AFM itself. These microscopes allow the simultaneous collection of topographical and other (e.g., viscoelastic, near-field optical) images of samples in the same portions. Thus, the combination of AFM and the other SPM has great potential for providing valuable new findings on structure and function of cells and tissues.