Application of high‐resolution scanning electron microscopy to biological macromolecules

Abstract

SUMMARY The development of ultrahigh‐resolution scanning electron microscopes (SEMs) has made the observation of biological macromolecules feasible, but adequate preparation methods have not yet been established. Although it has been possible to observe some molecules after they have been spread on a carbon substrate, this method has not proved suitable for other molecules which exhibit lower contrast, or are more susceptible to damage by the electron beam. In this study we have applied heavy‐metal impregnation methods using phosphotungstic acid, uranyl acetate, or osmium tetroxide mordanted by tannic acid. In addition, contamination due to the electron beam was reduced by improving the vacuum in the specimen chamber, and by the use of a heated specimen stage. Using these measures, haemocyanin, ferritin, apoferritin, thyro‐globulin and immunoglobulin M were successfully imaged. Ultrahigh‐resolution SEM seems likely to become an important means for studying the morphology of biological macromolecules.

Field emission in-lens SEM study of enamel and dentin

“…These values are in the range of resolution (2-35 nm) reported in numerous studies which used FEISEM to image biological macromolecules and cell structures. 20,21,[25][26][27][28] Thus, FEI-SEM has a clear resolution advantage over conventional SEM. Its resolution capabilities on demineralized dentin are comparable to those of cell structures and other macromolecules imaged by other types of high-resolution microscopies.…”

Two-dimensional crystallization of streptavidin by nonspecific binding to a surface film: study with a scanning electron microscope

“…A classical technique using a focused electron beam as probe, scanning (secondary) electron microscopy (SEM), has also made a remarkable progress in resolution to better than 10 A (Nagatani et al, 1987). Several proteins with relatively large molecular mass have been observed on electroconductive bulk plates with the high resolution SEM (HR-SEM) (Furuno et al, 1989(Furuno et al, , 1992Nakadera et al, 1991). Well contrasted raw images of 2D crystal of streptavidin (-50 A, -60 kDa) on a silicon wafer are presented in this paper.…”