ABSTRACT
Sensing of pyrophosphate ion (PPi) has received much attention due to the strong demand for clinical diagnostics. Here, based on gold nanoclusters (Au NCs), a ratiometric optical detection method for PPi is developed by simultaneously detecting the dual signals of fluorescence (FL) and second-order scattering (SOS). The PPi is detected by inhibiting the formation of aggregates of Fe3+ with Au NCs. Binding of Fe3+ to Au NCs causes aggregation of Au NCs, which leads to fluorescence quenching and scattering increasing. The presence of PPi can competitively bind Fe3+ to re-disperse the Au NCs and finally recover the fluorescence and reduce the scattering signal. The designed PPi sensor shows a high sensitivity with a linear range 5-50 µM and a detection limit of 1.2 µM. In addition, the assay has excellent selectivity for PPi, which makes its application in real biological samples extremely valuable.
Subject(s)
Gold , Metal Nanoparticles , Limit of Detection , Diphosphates , Spectrometry, Fluorescence/methods , Fluorescent DyesABSTRACT
A new method for conducting a reductive alkylation/arylation of 1,2-diketones using visible light and unactivated organic halides is presented in this article. This technique does not require a photocatalyst and employs Et3N, a tertiary amine, as a promoter. This amine aids in generating a ketyl radical and an α-aminoalkyl radical, which engages in a C-X bond activation via a halogen atom transfer process (XAT). This approach's success hinges on utilizing Et3N as the promoter. This article's mild and straightforward protocol allows for significantly expanding organic halide substrates, including primary, secondary, and aromatic organic halides and various functional groups.
ABSTRACT
Described here is a unprecedented organophotoredox/manganese dual catalyzed proton reduction and its application for semi-reduction of alkynes. The catalytic active pre-catalyst [Mn-1] can be feasibly be prepared on gram-scale from Mn(acac)2·2H2O in air. This dual catalytic protocol features noble-metal-free catalysts, simple ligand, and mild conditions. Besides, a unique ortho-halogen and -hydroxyl effect was observed to achieve high Z-stereoselectivity.
ABSTRACT
Ascorbic acid (AA) is an important diet-derived antioxidant to human body. Thus, efficient and accurate detection of AA is of considerable significance in food analysis. Herein, smartphone assisted colorimetric and fluorescent triple-channel signal sensor has been developed for AA monitoring based on oxidase-like CoOOH nanoflakes. CoOOH nanoflakes can efficiently catalyze the oxidation of p-phenylenediamine (p-PD) into reddish brown p-PDox. The carbon dots (C-dots) are further introduced, of which the fluorescence can be quenched by p-PDox. However, in the presence of AA, the CoOOH nanoflakes is reduced and thus collapsed. As a result, the oxidation of p-PD is restrained, and thus the fluorescence of C-dots keeps strong. Based on AA induced light color, low absorbance, and strong fluorescence, triple-channel signal sensor has been proposed for AA determination. The AA assay shows a dynamic response range from 0.5 to 10 µM with a detection limit of 0.09 µM. The method assay allows detection of AA in real samples such as fruit juices. Combination with portable smartphone, the developed sensor is potential for AA determination in resource-poor settings.
Subject(s)
Ascorbic Acid/analysis , Cobalt/chemistry , Food Analysis/methods , Fruit and Vegetable Juices/analysis , Nanostructures/chemistry , Oxides/chemistry , Colorimetry/methods , Nanostructures/ultrastructure , Oxidation-Reduction , Oxidoreductases/chemistry , Phenylenediamines/chemistry , SmartphoneABSTRACT
A resonance Rayleigh scattering (RRS) technique was utilized as a tool for isoelectric point monitoring and iron(III) cation determination. The spectral properties of some amphoteric molecules (proteins and a DNA sequence) were investigated using the RRS technique. When the pH values were kept at around their isoelectric points, especially high RRS signals could be obtained, which were much stronger than those at other pH values. By using the C30 DNA sequence as a probe, the iron(III) cation can be detected rapidly. After iron(III) was added to a C30 solution, a significantly decreased RRS signal was obtained. The sensing process can be finished within 10 min with a detection limit of 0.9 µM. Thus, a sensitive, selective, and label-free method was successfully developed for iron(III) detection.
ABSTRACT
A novel and concise method for the oxidation of unprotected indole derivatives to synthesize 2-indolylbenzoxazinones in the presence of AIBN under open air has been successfully demonstrated. This metal-free reaction is both atom- and step-efficient and is applicable to a broad scope of substrates. This new methodology provides a facile pathway for oxidative C2-C3 bond cleavage and recyclization of 1H-indoles.
