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The development of a portable sensor for on-site sensing of 2, 4, 6-trinitrotoluene (TNT) and other nitro aromatics (NAs) is still needed to strengthen environmental protection and public security. Herein, we report the fabrication of fluorescent few-layered MnO₂ nanosheets (FL-MnO₂ NSs) via N,N-dimethyl formamide-mediated ultrasonication and hydrothermal treatment. Electron and spectroscopy studies demonstrate that the modification of the FL-MnO₂ NSs (named as PEI-FL-MnO₂ NSs) with amine-rich polyethyleneimine (PEI) produced planar, β-phase, well-crystalline, and positively charged nanosheets. This PEI-related surface modification not only improves the quantum yield of the FL-MnO₂ NSs from 7.6 to 13.2% but also provides multiple binding sites with nitro groups of NAs. It was found that the presence of TNT, as an example of NAs, efficiently quenched the fluorescence of the PEI-FL-MnO₂ NSs due to the formation of Meisenheimer complexes through the efficient adsorption process. In comparison to PEI-modified MnO₂ quantum dots, the PEI-FL-MnO₂ NSs exhibited relatively high sensitivity to TNT with a limit of detection of 20 pM. By depositing PEI-FL-MnO₂ NSs on a filter paper, the as-made paper sensor was capable of visualizing 10 nM TNT in drinking water and 10 μM TNT on a postal envelope through the appearance of a quenching spot under a UV lamp. Besides, the adsorbed PEI polymer enables the PEI-FL-MnO₂ NSs to electrostatically interact with citrate-capped metal nanoparticles, producing the composites for catalyzing NaBH₄-mediated reduction of NAs. Since the PEI-FL-MnO₂ NSs possess a large surface area to capture NAs and serve as an electron acceptor for BH₄–, the formed composites efficiently catalyze the reaction of NaBH₄ and NAs as compared to metal nanoparticles and PEI-FL-MnO₂ NSs alone.

Reactive oxygen species (ROS) can induce oxidative stress and are associated with cell death and chronic diseases in organisms. In the treatment of disease, drugs that induce ROS are associated with many side effects and unpleasant symptoms. Therefore, during the assessment of new drugs and candidate compounds, ROS generation is an issue of concern, because ROS can modify proteins, lipids, and nucleic acids within organisms and alter their biological functions. In this work, we designed a peptide-based probe for the rapid (

The cathodic limit of the electrochemical window in the second-generation ionic liquids (composed of air- and water-stable metal-free cations and anions) is traditionally believed to be determined by the reduction of the cation. More and more exceptions, however, were found in various ionic liquids. In this study, the cathodic limit of the electrochemical window in 1-butyl-1-methylpyrrolidinium salicylate ionic liquid (BMP-SAL IL) was studied. It has been found that the cathodic limit of BMP-SAL is determined by the reduction of SAL(-) anion rather than the reduction of BMP(+) cation. The cyclic voltammetric behavior, NMR spectra, and MALDI-TOF MS spectra of BMP-SAL recorded before and after the IL was electrolyzed at the cathodic limit provide sufficient evidence that the major reaction at the cathodic limit of BMP-SAL is the reduction of SAL(-) anion. The theoretical calculations support the experimental data, and the results indicate that anion reduction dominated cathodic limit should be a common phenomenon in ionic liquids.

(G:3-7)-dendri-PAMAM-(APO-Phe-Lys)(x) (2, APO = aminopropanol, Phe = phenylalanine, Lys = lysine) were prepared and used in a binding study with pyridoxal 5'-phosphate. The results revealed a positive dendritic effect, and binding ability was found to vary with the environment. (G:3-7)-dendri-PAMAM-(APO-Phe-Lys)(x) (2) demonstrated better binding ability at higher pH, and protonation of lysine was considered to affect binding. The strongest binding affinity was K(b) = 254.3 mM(-1) at pH 9, which was shown by (G:7)-dendri-PAMAM-(APO-Phe-Lys)(490) (2e).