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The article studies the general peroxidase activity of G-quadruplex-hemin complexes and link between peroxidase activity and G-quadruplex structures. Findings reveal that peroxidase activity is applicable for screening G-quadruplex ligands.

Low thermal conductance across interface is often the limiting factor in managing heat in many advanced device applications. The most commonly used approach to enhance the thermal conductance is to reduce/eliminate the interfacial structural defects. Using a graphene/h-BN (Gr/h-BN) interface, we show surprisingly that topological defects are able to enhance the thermal conductance across the interface. It is found that the phonon transmission across the Gr/h-BN interface with 5|7 defects is higher than that of the pristine interface, which is in strong contrast to the common notion that interface defects promote phonon scattering. By analyzing the strain distribution and phonon vibrational spectra, we find that this abnormal enhancement in interfacial thermal conductance originates from the localization of the stress fields arising from misfit dislocations and their out-of-plane deformations at the interface. In the presence of the defects, the overall mismatch strain is reduced. In addition, the out-of-plane deformations screen the long-ranged dislocation strain fields, resulting in the stress fields to be localized only at the cores of the defects. This abnormal mechanism provides a new dimension to enhance the interfacial thermal conductance in two-dimensional heterostructures. [ABSTRACT FROM AUTHOR]

A simple and effective strategy for designing ratiometric fluorescent nanosensor has been described in this work. A carbon dots (CDs) based dual-emission nanosensor for Cu2+ detection was prepared by coating CDs on the surface of Rhodamine B-doped silica nanoparticles. The fluorescent CDs were synthesized using N-(β-aminoethyl)-γ-aminopropyl methyldimethoxysilane (AEAPMS) as the main raw material, so that the residual ethylenediamine groups and methoxysilane groups on the surface of CDs can serve as the Cu2+ recognition sites and the silylation reaction groups. The obtained nanosensor showed characteristic fluorescence emissions of Rhodamine B (red) and CDs (blue) under a single excitation wavelength. Upon binding to Cu2+, only the fluorescence of CDs was quenched, resulting in the ratiometric fluorescence response of the dual-emission silica nanoparticles. This ratiometric nanosensor exhibited good selectivity to Cu2+ over other substances, such as metal ions, amino acids, proteins, and vitamin C. The ratio of F467/F585 linearly decreased with the increasing of Cu2+ concentration in the range of 0 to 3 × 10–6 M, a detection limit as low as 35.2 nM was achieved. Additionally, this nanosensor was successfully applied for the ratiometric fluorescence imaging of Cu2+ in cells and determination of Cu2+ in real tap water. [ABSTRACT FROM AUTHOR]

Here we describe a highly selective and reversible Hg2+ sensor, tetra-(thymin-1-yl-acetamido)-phthalocyanine Zn(II) (4T-ZnPc), which combined the optical properties of phthalocyanine (Pc) and the specific interaction of Hg2+ with thymine (T). The novel phthalocyanine-nucleobase conjugate, 4T-ZnPc, shows a typical ultraviolet—visible absorption spectrum with a split Q-band of monomeric Pc in diinethylformamide (DMF)—water (7:3, v/v) solution, as well as strong fluorescence emission. Upon addition of Hg2+, the formation of T—Hg—T complex induces aggregation of 4T-ZnPc and results in significant decreases of fluorescence intensity and absorption of the Q-band. Furthermore, the sensor molecules, 4T-ZnPc, show excellent selectivity for Hg2+, and other ions, such as Pb2+, Co2+, Ni2+, Zn2+, Cd2+, Mn2+, Mg2+, Ca2+, Na+, and K+, have almost no effect on the optical properties of 4T-ZnPc. This kind of sensor based on Pc may be expanded to the detection of other targets by substituting thymines with other ligands or groups that possess molecular recognition ability. [ABSTRACT FROM AUTHOR]

In this work, the adsorption behaviors of CH4 in slit-like kaolinite pores were investigated using the grand canonical Monte Carlo method. The research results show that the isosteric heat of adsorption of CH4 decreases with increasing pore size and that CH4 adsorption on kaolinite can be characterized as physical adsorption. The potential energy between CH4 and kaolinite was found to decrease with increasing pressure or decreasing pore size, indicating that the adsorption sites of CH4 changed from higher-energy adsorption sites to lower-energy adsorption sites. The CH4 adsorption capacity decreased with increasing pore size in mesopores. With increasing temperature, the isosteric heat of adsorption of CH4 decreased, and the adsorption sites of CH4 changed from higher-energy adsorption sites to lower-energy adsorption sites, resulting in a decrease of the CH4 adsorption capacity. As a result of van der Waals force interactions, Coulomb force interactions, and hydrogen-bonding interactions, the water molecules in the kaolinite pores occupies the pore walls in a directional manner, causing the water molecules in the kaolinite pores to accumulate. With increasing accumulation of water, the water molecules occupied adsorption spaces and adsorption sites of CH4, leading to a decrease of the CH4 adsorption capacity. The gas adsorption capacity on kaolinite was found to decrease in the following order: CO2 > CH4 > N2. With increasing mole fraction of N2 or CO2, the mole fraction of CH4 in the gas phase decreased, the adsorption sites of CH4 changed, and the adsorption space of CH4 decreased, resulting in a decrease of CH4 adsorption capacity. [ABSTRACT FROM AUTHOR]