MICROSCOPY Vol.47▶No.1 2012
■Researches Today

Development of Adaptive SEM Technology for in situ Molecular Expression Analysis in Single Cell Level Using Nano-Particle Probe Array Consisting of Various Elements

Hyonchol Kim, Hideyuki Terazono, Hiroyuki Takei and Kenji Yasuda

Abstract: We have developed an “adaptive SEM” technology; a newly developed nano-particle probe set for simultaneous labeling of different target molecules was combined with backscattered electron (BE) observation mode of field emission scanning electron microscopy (FE-SEM) to carry out single-molecular expression analysis. Polystyrene spheres prepared with precise size control were used as a template for production of nano-particle probe sets; various elements were thermally deposited on these template spheres. After removal of the template, cup-shaped metal nano-particle probes were obtained. By varying the size and element, more than 500 kinds of probes with different characteristics were obtained. Identification of nano-particle probes was accomplished by comparing BE intensities reflecting differences in the atomic number in FE-SEM with a pre-established BE image library of metal nano-particles. By using the “adaptive” SEM technology (i.e., nano-particle identification is “adaptive” under various sample conditions), we could simultaneously identify six different elements with hardly any increase in measurement time and spatial resolution in comparison to secondary electron observation. This wide-reaching technology based on nano-particle labeling and BE analysis could allow simultaneous detection of a large number of target biomolecules at a single-cell level with a nanometer spatial resolution, holding great promise for the post-genome/proteome era.

Key words: Adaptive electron microscopy, Backscattered electron observation, Metal nano-particles, Single cell measurement, Scanning electron microscopy