Dynamic nano-imaging of label-free living cells using electron beam excitation-assisted optical microscope

Abstract

Optical microscopes are effective tools for cellular function analysis because biological cells can be observed non-destructively and non-invasively in the living state in either water or atmosphere condition. Label-free optical imaging technique such as phase-contrast microscopy has been analysed many cellular functions, and it is essential technology for bioscience field. However, the diffraction limit of light makes it is difficult to image nano-structures in a label-free living cell, for example the endoplasmic reticulum, the Golgi body and the localization of proteins. Here we demonstrate the dynamic imaging of a label-free cell with high spatial resolution by using an electron beam excitation-assisted optical (EXA) microscope. We observed the dynamic movement of the nucleus and nano-scale granules in living cells with better than 100 nm spatial resolution and a signal-to-noise ratio (SNR) around 10. Our results contribute to the development of cellular function analysis and open up new bioscience applications.

Visualization of ultraviolet absorption distribution beyond the diffraction limit of light by electron‐beam excitation‐assisted optical microscope

“…The 1024 × 1024 pixels image was obtained. There is little damage under the observation conditions where live cells were observed (Fukuta et al ., ). The specimen is vitamin B9 and the absorption wavelength of the vitamin B9 (Off et al ., ; Matias et al ., ) matches with the wavelength of the UV emission of the luminescent thin film installed in the EXA optical microscope.…”

“…We demonstrated super‐resolution absorption contrast imaging with electron‐beam excitation‐assisted (EXA) optical microscope. The EXA microscope can observe a specimen without staining with fluorescent dye (Inami et al ., ; Fukuta et al ., ; Fukuta et al ., ). A nano‐sized optical spot is generated by irradiating a focused electron beam to a luminescent film, because an electron beam can be focused to a nanometer‐sized spot.…”

Hybrid nanocomposite curcumin-capped gold nanoparticle-reduced graphene oxide: Anti-oxidant potency and selective cancer cytotoxicity

“…The evaluation of CAG as an anti-cancer agent was studied using an in vitro colon cancer model through cellular morphologic changes and viability measurements. Optical phase-contrast microscopy provides an essential tool to visualize morphological changes which serve as crucial indication for treatment efficacy in inducing cell injury and death [106–108]. Viability assay, on the other hand, determines intracellular physiological capabilities and the metabolic states of treated cells.…”

Cardiovascular bioimaging of nitric oxide: Achievements, challenges, and the future

“…However, concerns associated with translational applications of SWCNT such as toxicity and accumulation in tissues exist 129 . Label‐free imaging of NO using ultrasound, autofluorescent optical signals, and electron beam excitation‐assisted optical microscopy 130 can be used to assess NO‐mediated cellular functions. Research on such methods is needed to minimize procedure‐related toxicity, which is a major concern when using carbon or metal‐based nanoparticles as probes or contrast media.…”