Volume 54 Issue 6, June 2022

In this review, we overview the recent advances associated with seminal findings in the development of nucleic acid-based fluorescent sensor systems aimed at application for exploring intracellular phenomena. We described the fluorescence signal generation mechanisms of each nucleic acid-based fluorescent sensor, including molecular beacon and quencher-free linear probes, as well as aptamer or DNAzyme-based systems. In addition, cascade hybridization chain reaction and catalyzed hairpin assembly are introduced as methods for amplifying fluorescence signals under isothermal conditions.

Reverse osmosis (RO) membranes are widely used as energy-saving and environmentally friendly materials for water purification. This Focus Review reports on the nanoscale structure and permeation mechanism of crosslinked fully aromatic polyamide RO membranes. First, the research on the morphology of protuberance structures of the polyamide separation functional layer is described. Next, hydrated structure of the functional layer is focused, which was analyzed using neutron scattering and molecular dynamics simulations. Innovative RO membranes are being developed that can obtain higher quality water with less energy by precisely controlling nanostructures.

Perfect syndiospecific polymerization of triphenylamine-substituted styrene derivatives were achieved by using a rare-earth metal catalyst. The copolymerization of FSt with Styrene afforded copolymers have random or gradient sequence distributions and easily tunable incorporation rate.

Using LV-STEM, we found that there were previously unseen nanoscale structures inside the blends of PMMA/PVDF. These structures were formed on the same scale that did not deviate from the size of a single molecular chain, regardless of the solution casting, melt mixing, mixing ratios, and even amorphous or crystalline state of PVDF. The characteristics of these structures were discussed in accordance with thermophysical properties and intermolecular interaction properties, which provides some new findings for the first time.

The PEDOT: PSS/PNIPAM hydrogel was simply prepared by ultrasound-enhanced free radical polymerization in an ice bath, in open air rather than spending hours under an N₂ purged environment. The resulting conductive hydrogel had a uniform texture and good flexibility for rapid resistance responses and color changes when it was exposed to temperature stimulations. The dual actions of hydrogen bonding and hydrophobic aggregation weaken the Coulomb interaction between PEDOT⁺ and PSS⁻ for better conductivity that is suitable for breathing monitoring and other wearable sensing applications.

A newly synthesized polyurethane (PU) was used to increase the flexibility of Bombyx mori silk fibroin (SF) fiber by making a composite of SF and PU, which is expected to increase applications of SF fiber in biomaterials. Namely, the elongation at break of the fiber increased by 1.3–1.8 times compared with that of regenerated SF fiber. The main reason for the increased flexibility of the SF-PU composite fiber is the increase in the fraction of random coils in SF, which was clearly observed by ¹³C solid-state NMR.

Crystalline embryos initiated at early stage of the spinodal decomposition (SD) grew to anisotropically shaped crystallites and then the neighboring crystallites were collided by interpenetration of the lamellae within the continuous bisphenol-A polycarbonate (BPA-PC) rich phase at late stage of the SD. Such characteristic crystallization behavior is attributed to the constraint crystallization growth within the continuous BPA-PC rich region due to interconnected phase structure obtained by the liquid–liquid phase separation via SD.

Nanostructured polymer membranes were prepared from ionic liquid-crystalline (LC) monomers with taper-shaped mesogens. The virus removal properties of the ionic 1D channels prepared from a columnar (Col) LC phase were examined. In addition, as the first approach for LC membranes, the removal of several viruses from their cocktail solution by the 1D channels of Col membrane and 3D channels of bicontinuous cubic membrane was also studied.