High-resolution, label-free imaging of living cells with direct electron-beam-excitation-assisted optical microscopy

Virtual reality images created on the back and front of a display

To better investigate the biological mechanism of microorganisms, we developed a novel, to the best of our knowledge, virtual reality (VR) microscope that incorporates a head-mounted display (HMD) that creates VR images with a digital microscope. This type of VR microscope can be used with any type of optical microscope. The fabricated microscope is quite different from a common bifocal device because it can create VR images on the back and front of a display. If the VR images are displayed with object (OBJ) images, they are observable in [2 × 2] (back and front VR images and OBJ images; 2 × 2 = 4 images). This feature can provide important information on microscopic OBJs, which can be employed in 3D biological analysis. Furthermore, if a laser light source is added to this microscope, the images can be observed in [3 × 2] (back and front laser VR images, VR images, and OBJ images; 3 × 2 = 6 images). The lasers would also enable optical trapping and tracking, leading to improved biological analysis.

Cell structure imaging with bright and homogeneous nanometric light source

Label-free optical nano-imaging of dendritic structures and intracellular granules in biological cells is demonstrated using a bright and homogeneous nanometric light source. The optical nanometric light source is excited using a focused electron beam. A zinc oxide (ZnO) luminescent thin film was fabricated by atomic layer deposition (ALD) to produce the nanoscale light source. The ZnO film formed by ALD emitted the bright, homogeneous light, unlike that deposited by another method. The dendritic structures of label-free macrophage receptor with collagenous structure-expressing CHO cells were clearly visualized below the diffraction limit. The inner fiber structure was observed with 120 nm spatial resolution. Because the bright homogeneous emission from the ZnO film suppresses the background noise, the signal-to-noise ratio (SNR) for the imaging results was greater than 10. The ALD method helps achieve an electron beam excitation assisted microscope with high spatial resolution and high SNR.

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

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.