Comparison of Scanning Ion-Conductance Microscopy with Scanning Electron Microscopy for Imaging the Surface Topography of Cells and Tissues

Abstract

Images of cells and tissues obtained by scanning ion-conductance microscopy (SICM) were compared with those obtained by scanning electron microscopy (SEM). Samples chemically fixed with glutaraldehyde were first observed using SICM in a phosphate buffer solution. Conductive staining was applied, followed by critical point drying; samples were then coated with metal and observed by scanning electron microscopy (SEM). Using this technique, SICM and SEM images of the same portions in different cells (COS-7, Mm2T.P3, and HeLa cell lines) and tissues (rat trachea, organ of Corti, and renal glomerulus) were compared to assess the quality of SICM and SEM images. The imaging quality of SICM was excellent and sufficient to investigate the three-dimensional surface structure of cells and tissues, although optimized imaging conditions (including the threshold and adjustment of pH) are essential to ensure the quality of SICM images. The main advantage of SICM imaging is that it can obtain topographic images of cells and tissues in an aqueous medium, which is not possible with conventional SEM imaging. SICM also has the advantage of avoiding SEM preparation artifacts, such as shrinkage and deformation produced by drying and metal coating. Although the imaging time needs to be improved, SICM is expected to be useful for observing cells and tissues to reveal their three-dimensional structure at a high resolution, similar to SEM.