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Cysteine (Cys) is a critical biologically active sulfhydryl molecule that plays essential roles in anti-oxidation and maintains protein structure and function. In addition, Cys is also a vital nutrient in many foods. Therefore, the detection of Cys is highly required for food quality control and revealing the biological functions of Cys. Herein, we presented an effective fluorescent probe (denoted as DDP-C) for sensing Cys. The probe can produce a swift off–on fluorescence response to Cys and two other significant biothiols (homocysteine and glutathione) with emission in the deep-red to the near-infrared region (600–700 nm). The probe has a large Stokes shift (140 nm), as well as high selectivity and sensitivity. The linear range for Cys detection is 0.5–20 μM, and the detection limit is 37 nM. DDP-C can also realize the quantitative determination of Cys in milk samples and imaging of intracellular biothiols. Therefore, the probe can serve as a powerful tool for Cys sensing. [ABSTRACT FROM AUTHOR]

Emulating the function of natural carboxylases to convert CO2 under atmospheric condition is a great challenge. Herein we report a class of CO2‐folded single‐chain nanoparticles (SCNPs) that can function as recyclable, function‐intensified carboxylase mimics. Lewis pair polymers containing bulky Lewis acidic and basic groups as the precursor, can bind CO2 to drive an intramolecular folding into SCNPs, in which CO2 as the folded nodes can form gas‐bridged bonds. Such bridging linkages highly activate CO2, which endows the SCNPs with extraordinary catalytic ability that can not only catalyze CO2‐insertion of C(sp3)‐H for imitating the natural enzyme's function, it can also act on non‐natural carboxylation pathways for C(sp2 and sp)‐H substrates. The nanocatalysts are of highly catalytic efficiency and recyclability, and can work at room temperature and near ambient CO2 condition, inspiring a new approach to sustainable C1 utilization. [ABSTRACT FROM AUTHOR]

In this study, fluorescent silver nanoclusters (Ag NCs) were synthesized using denatured fish sperm DNA as the template. In contrast to other methods, this method did not use artificial DNA as the template. After their reaction with denatured fish sperm DNA, Ag+ ions were reduced by NaBH4 to form Ag NCs. The Ag NCs showed a strong fluorescence emission at 650 nm when excited at 585 nm. The fluorescence intensity increased fourfold at pH 3.78, controlled with Britton-Robinson buffer solution. The fluorescence of the Ag NCs was quenched in the presence of trace mercury ions (Hg2+) in a weakly acidic medium and nitrogen atmosphere. The extent of the fluorescence quenching of Ag NCs strongly depends on the Hg2+ ion concentration over a linear range from 2.0 nmol L−1 to 3.0 μmol L−1. The detection limit (3σ/k) for Hg2+ was 0.7 nmol L−1. Thus, a sensitive and rapid method was developed for the detection of Hg2+ ions. [ABSTRACT FROM AUTHOR]

The group effect on ionization potential for mono-substituted aliphatic compounds RX was investigated, and it was found that there is a good relationship between the ionization potential ( IP) and the parameters, group electronegativity χeq,X, the group polarizability ∑ PEIX, and the disperse contribution of single non-bond electron Edc for titled compounds, and these parameters earlier were easily calculated from the molecular structure. Moreover, the B3LYP density functional method was also employed to estimate IP values of the same mono-substituted aliphatic compounds. The results showed that it was difficult to get reliable ionization data using DFT method, and the regression equation with descriptors χeq,X, ∑ PEIX, and Edc was more effective than DFT method in predicting IP values for titled compounds. The results are helpful to understand the role of group effect on molecular properties. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The article focuses on a study which investigated the connection on the nuclear magnetic resonance (NMR) chemical shifts of bridge carbons for various series of aromatic Schiff bases. Topics discussed include the computation of chemical shift values in determining the NMR of specific carbons for aromatic systems, the strength of substituent inductive effect based on conventional chemistry theory, and the reliability and application of chemical shifts for various aromatic Schiff bases.

A novel amphoteric chelating polymer flocculant (ACPF) was synthesized. The synthesis involved the copolymerization of dimethyldiallylammonium chloride and acrylamide to prepare poly(dimethyldiallylammonium chloride- co-acrylamide) [P(DMDAAC- co-AM)], Mannich reaction of P(DMDAAC- co-AM) with triethylenetetramine and formaldehyde to prepare P(DMDAAC- co-AM)- graft-TETA, and xanthogenation of P(DMDAAC- co-AM)- graft-TETA with CS2 and NaOH. The removal performance of ACPF toward Cu2+ was investigated, and the ACPF structure was characterized. ACPF performance considerably improved at 121-187 mL/g intrinsic viscosity, 20.78-28.32 mol % cationic degree of P(DMDAAC- co-AM), and 22.11-28.44% sulphur content of ACPF. The Cu2+ removal rate was above 99% at a 1.98 : 1 molar ratio of -CSS− to Cu2+. This rate was 5.86% higher than that using polyacrylamide- graft-triethylenetetramine-dithiocarbamate (PAM- graft-TETA-DTC). The zeta potential and sedimentation rate of flocs obtained from ACPF were higher and their volume was smaller than those from sodium triethylenetetramine-multidithiocarbamate and PAM- graft-TETA-DTC at the same sulphur dosage. This result indicates that the positive charges of ACPF polymeric chains effectively neutralize excess negative charges in flocs, which benefits the bridging of flocs with negative charges to promote their formation and growth. These positive charges can also cause the flocs to become larger and tighter, thereby improving flocculation and settling performance. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Photoswitchable polymeric materials are promising candidates for rewritable patterning and optical information storage. However, traditional solid photoswitchable polymers are generally hampered by a low fatigue resistance and slow photoresponse. To overcome these two key deficiencies, in this study, we examined a simple synthetic strategy for producing photoswitchable polyurethane films via the covalent attachment of an excellent photochromic diarylethene. The as‐prepared diarylethene‐based polyurethane (DTE–PU) film showed rapidly reversible isomerization and splendid photoreversibility (>20 times). Additionally, the as‐prepared DTE–PU film in the closed form possessed outstanding thermal irreversibility and long‐term optical stability. Photowritten patterns on the DTE–PU film remained steady for more than 2 weeks. These eminent properties made the DTE–PU film a promising candidate for multifarious applications, including rewritable patterning and stable optical information storage. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47466. A photoswitchable diarylethene‐based crosslinked polyurethane film (DTE–PU) with good mechanical properties and excellent photoswitchable natures was prepared. Moreover, DTE–PU film in the close‐ring form has good thermal irreversibility and long‐term optical stability. The eminent properties imply the great potential in rewritable patterning and stable optical information storage. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) is an important bioactive molecule that plays a significant role in various functions, particularly in the living brain, where it is closely linked to cognition, memory, and several neurological diseases. Consequently, developing effective detection methods for H 2 S is essential for studying brain functions and the underlying mechanisms of these diseases. This study aims to construct a novel photoelectrochemical (PEC) microelectrode Ti/TiO 2 @HSP for the quantitative monitoring of H 2 S levels in the living brain. The PEC microelectrode Ti/TiO 2 @HSP is formed by covalently bonding a specifically designed organic PEC probe HSP, which possesses a D-π- A structure, to the surface of TiO 2 nanotubes generated via in situ anodic oxidation of titanium wire. The PEC probe HSP can effectively react with H 2 S and generate significant photocurrent response under long-wavelength excitation light (560 nm), thereby achieving quantitative detection of H 2 S. The sensor demonstrates high sensitivity and good selectivity. In vivo experiments utilizing the PEC microelectrode Ti/TiO 2 @HSP enable the monitoring of dynamic changes in H 2 S levels across various regions of the mouse brain. The findings reveal that in normal mice, the concentration of H 2 S in the hippocampus is significantly higher than in the striatum and cerebral cortex. Additionally, following propargylglycine drug stimulation, H 2 S concentrations in different brain regions were observed to decrease, with the most substantial reduction noted in the hippocampus. This suggests that cystathionine γ-lyase (CSE) is the primary enzyme responsible for H 2 S production in this area, while the striatum exhibits a less pronounced decrease in H 2 S concentration, indicating a reliance on alternative enzymatic pathways for H 2 S production. Therefore, this study not only successfully develops a high-performance H 2 S detection sensor but also provides new experimental tools and theoretical foundations for further exploring the roles of H 2 S in neurophysiological and pathological processes.

In this study, fluorescent silver nanoclusters (Ag NCs) were synthesized using denatured fish sperm DNA as the template. In contrast to other methods, this method did not use artificial DNA as the template. After their reaction with denatured fish sperm DNA, Ag + ions were reduced by NaBH 4 to form Ag NCs. The Ag NCs showed a strong fluorescence emission at 650 nm when excited at 585 nm. The fluorescence intensity increased fourfold at pH 3.78, controlled with Britton-Robinson buffer solution. The fluorescence of the Ag NCs was quenched in the presence of trace mercury ions (Hg 2 + ) in a weakly acidic medium and nitrogen atmosphere. The extent of the fluorescence quenching of Ag NCs strongly depends on the Hg 2 + ion concentration over a linear range from 2.0 nmol L -1 to 3.0 μmol L -1 . The detection limit (3σ/k) for Hg 2 + was 0.7 nmol L -1 . Thus, a sensitive and rapid method was developed for the detection of Hg 2 + ions., (Copyright © 2016 John Wiley & Sons, Ltd.)