Coronavirus disease 2019 (COVID-19) is newly emerging human infectious diseases, which is caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2, also previously known as 2019-nCoV). Within two months of the outbreak, more than 80,000 cases of COVID-19 have been confirmed worldwide. Since the human to human transmission occurred easily and the human infection is rapidly increasing, the sensitive and early diagnosis is essential to prevent the global outbreak. Recently, World Health Organization (WHO) announced various primer and probe sets for SARS-CoV-2 previously developed in China, Germany, Hong Kong, Japan, Thailand, and USA. In this study, we compared the ability to detect SARS-CoV-2 RNA among the seven primer-probe sets for N gene and the three primer-probe sets for Orf1 gene. The result of the comparative analysis represented that the ‘2019-nCoV_N2, N3’ of USA and the ‘ORF1ab’ of China are the most sensitive primer-probe sets for N and Orf1 genes, respectively. Therefore, the appropriate combination from ORF1ab (China), 2019-nCoV_N2, N3 (USA), and NIID_2019-nCOV_N (Japan) sets should be selected for the sensitive and reliable laboratory confirmation of SARS-CoV-2.

Fibrous aggregates of Tau protein are characteristic features of Alzheimer disease. We applied high resolution atomic force and EM microscopy to study fibrils assembled from different human Tau isoforms and domains. All fibrils reveal structural polymorphism; the "thin twisted" and "thin smooth" fibrils resemble flat ribbons (cross-section ϳ10 ؋ 15 nm) with diverse twist periodicities. "Thick fibrils" show periodicities of ϳ65-70 nm and thicknesses of ϳ9 -18 nm such as routinely reported for "paired helical filaments" but structurally resemble heavily twisted ribbons. Therefore, thin and thick fibrils assembled from different human Tau isoforms challenge current structural models of paired helical filaments. Furthermore, all Tau fibrils reveal axial subperiodicities of ϳ17-19 nm and, upon exposure to mechanical stress or hydrophobic surfaces, disassemble into uniform fragments that remain connected by thin thread-like structures (ϳ2 nm). This hydrophobically induced disassembly is inhibited at enhanced electrolyte concentrations, indicating that the fragments resemble structural building blocks and the fibril integrity depends largely on hydrophobic and electrostatic interactions. Because full-length Tau and repeat domain constructs assemble into fibrils of similar thickness, the "fuzzy coat" of Tau protein termini surrounding the fibril axis is nearly invisible for atomic force microscopy and EM, presumably because of its high flexibility.

Single-molecule force measurement methods have attracted increasing interest over recent years for the development of novel approaches for biomolecular screening. However, many of these developments are currently hindered by the available biomolecule surface attachment methods, in that it is still not trivial to create surfaces and devices with highly defined surface functionality and/or uniformity. Here we offer a new approach to address such issues based on the formation of dendron arrays. Through the measurement of forces between dendron surfaces functionalized with complementary DNA oligonucleotides, we observed several unique properties of the surfaces modified via this approach. The capability to record attractive or "jump-in" forces associated with molecular binding events is one of them. Additionally, these events occur in greater than 80% of measurements, and the forces are dependent on the number of complementary DNA bases of the associating strands while being insensitive to the measurement rate. Combined with a narrow distribution of both attractive forces and unbinding forces we suggest such functionalized surfaces offer a significant advance for fast and accurate force-based studies of oligonucleotide hybridization.

A new nanopatterning system based on a soft X-ray induced chemical transformation of a nitro-substituted aromatic imine monolayer has been developed. The molecular layer was exposed to soft X-rays, and the involved chemical transformation on the molecular layer was analyzed by using Fourier transform infrared reflection−absorption spectroscopy. As a result, we could confirm that the nitro group on the imine monolayer was cleaved upon the soft X-ray irradiation, leaving the hydrophobic phenyl unit intact on the monolayer surface, while the imine functionality was transformed into a new nonhydrolyzable one. However, the source of the hydrogen atom for the reduction and the final functionality at the para position of the aromatic group are unknown yet. Whereas, we could restore the hydrophilic amine functionality from the unexposed imine monolayer through hydrolysis. These phenomena were applied to the patterning of self-assembled monolayers featuring alternating height, chemical reactivity, and wettability. Alternating surface wettability is evident when water is sprayed on a macroscopically patterned substrate and the plate is tilted to drip the water. Also, atomic force microscope images revealed patterns as small as ≤100 nm with regular height and phase variations. The patterned monolayer was further modified with a linker and Cy3-tagged oligonucleotide, sequentially. Fluorescence images showed that the above molecules were selectively immobilized onto the amine-terminated region of the patterned surface.