Single crystal nanoplates with thickness less than 30 nm, characterized by hexagonal and truncated triangular shapes bounded mainly by [111] facets, were obtained in large quantities by aspartate reduction of gold chloride.

Lithium-sulfur batteries are a promising high energy output solution for substitution of traditional lithium ion batteries. In recent times research in this field has stepped into the exploration of practical applications. However, their applications are impeded by cycling stability and short life-span mainly due to the notorious polysulfide shuttle effect. In this work, a multifunctional sulfur host fabricated by grafting highly conductive Co 3 Se 4 nanoparticles onto the surface of an N-doped 3D carbon matrix to inhibit the polysulfide shuttle and improve the sulfur utilization is proposed. By regulating the carbon matrix and the Co 3 Se 4 distribution, N-CN-750@Co 3 Se 4 -0.1 m with abundant polar sites is experimentally and theoretically shown to be a good LiPSs absorbent and a sulfur conversion accelerator. The S/N-CN-750@ Co 3 Se 4 -0.1 m cathode shows excellent sulfur utilization, rate performance, and cyclic durability. A prolonged cycling test of the as-fabricated S/N-CN-750@Co 3 Se 4 -0.1 m cathode is carried out at 0.2 C for more than 5 months which delivers a high initial capacity of 1150.3 mAh g −1 and retains 531.0 mAh g −1 after 800 cycles with an ultralow capacity reduction of 0.067% per cycle, maintaining Coulombic efficiency of more than 99.3%. The reaction details are characterized and analyzed by ex situ measurements. This work highly emphasizes the potential capabilities of transition-metal selenides in lithium-sulfur batteries.

This work demonstrates the significant fluorescence enhancement of thioflavin T (ThT) when binding to G-quadruplexes possessing hybrid structures by using UV–vis absorption spectra, fluorescence spectra, and T m experiments to confirm the binding events. ThT binding does not disturb native G-quadruplex structures preformed in Na+ and K+ solutions. The fluorescence enhancement is caused by the rotation restriction of benzothiazole (BZT) and dimethylaminobenzene (DMAB) rings in the ThT excited state upon its G-quadruplex binding. This molecular rotor mechanism as a means of fluorescence enhancement is confirmed using a nonrotor analogue of ThT. Hydroxylation and electrolyte experiments demonstrate that ThT stacks on the tetrad of the hybrid G-quadruplexes, whereas electrostatic forces contribute more to ThT binding for other G-quadruplex structures. By stacking on the tetrad, the ThT binding favors selective identification of DNA hybrid G-quadruplex structures with enhanced fluorescence and can serve as a conformation probe to monitor G-quadruplex structure conversion between hybrid and other structures. Using these properties, we developed a selective and label-free fluorescent K+ sensor with a detection limit of 1 mM for K+ in the presence of 100 mM Na+. The coexistence of other metal ions produces a fluorescence response comparable to K+ alone. We believe that ThT can potentially provide structure identification of hybrid G-quadruplexes and aid in the construction of G-quadruplex-based sensors.

Water-soluble and red-emitting gold nanoclusters (Au NCs) were synthesized with single-stranded DNA as a promising biotemplate and dimethylamine borane as a mild reductant. The fluorescent Au NCs can be formed in a weakly acidic aqueous solution that is free from the simultaneous formation of large nanoparticles. The cluster feature of the formed Au species has been revealed by fluorescence spectra, absorption spectra, and transmission electron microscopy. Additionally, DNA sequences could be used to tune the Au NCs' emissions. The as-prepared Au NCs display high stability at physiological pH condition, and thus, wide potential applications are anticipated for the biocompatible fluorescent Au NCs serving as nanoprobes in bioimaging and related fields.