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Visual electrochemiluminescence (ECL) emission from L012 and hydrogen peroxide is generated from an all-solid-state electrochemical cell with a polyacrylamide hydrogel as the solid electrolyte. The emission is strong enough to be visualized with the naked eye, which offers a new idea for the design of an all-solid-state ECL based sensor in air. [ABSTRACT FROM AUTHOR]

Silicon quantum dots (QDs) with stable positively charged intermediates are prepared using chemical etching to generate strong anodic electrochemiluminescence (ECL) under a positive potential. Their surfaces could be passivated in the presence of strong oxidants, leading to enhanced ECL and offering the ability to carry out analysis for hydrogen peroxide. [ABSTRACT FROM AUTHOR]

Histopathological molecular testing of tissue sections is an essential step in tumor diagnosis; however, the commonly used immunohistochemical methods have problems such as low specificity and the subjective bias of the observer. Here, we report an electrochemiluminescence (ECL) imaging method to detect a membrane carcinoembryonic antigen (CEA) at the single tissue sections of cancer patients. By permeabilizing the tissue attached to a glassy carbon electrode, Ru(bpy)32+ tagged at the membrane CEA of the tissue could electrochemically react with TPrA in solution to emit ECL that has near-zero background and an extremely high signal-to-background ratio. Using the established ECL method, the expression differences and distribution characteristics of the CEA protein in the carcinoma and paracancerous tissues of pancreatic ductal carcinoma (PDAC) and lung adenocarcinoma (LUAD) patients are investigated. The images reveal that CEA proteins are mostly distributed in the acini and surrounding areas both in PDAC and LUAD tissues. Therefore, the presented approach could be able to provide a new molecular recognition method for the diagnosis of adenocarcinoma and other tumors. [ABSTRACT FROM AUTHOR]

Compared with the well-studied cations, the development of methods for anion detection is relatively slow due to the anion characteristics such as a complex geometry, strong hydration and a low charge density. Herein, a colorimetric and ratiometric fluorescent anion sensing platform based on trihexyltetradecylphosphonium chloride ([THTP][Cl]) was developed for the first time. Such nanosensors exhibited a pH response of 5–7 as well as a high selectivity to perchlorate. The selectivity behavior followed the Hofmeister series in which lipophilic anions were more readily co-extracted. To deviate from the Hofmeister series, anion ionophores should be introduced for selective complexation of the target anions. As a proof of concept, the organomercury compounds ETH9033 and ETH9009 were employed as model ionophores. The obtained nitrate- and chloride-selective [THTP][Cl]-based nanosensors demonstrated prominent colorimetric and spectroscopic transformations specifically induced by the anion species. The fluorescence (I675/I600) and absorbance (A650/A500) intensities versus the logarithm values of anion concentrations proved a high selectivity towards the major anion. The excellent performance such as high selectivity, good sensitivity and fast response times enabled the accurate determination of nitrate in mineral water. More importantly, through simply altering the ionophores, a pool of [THTP][Cl]-based anion-selective nano-optodes for extended targets could be achieved. The nanosensor shows great potential for anion determination in the environmental and biomedical fields. [ABSTRACT FROM AUTHOR]

Conventional photoelectrochemical (PEC) analysis mostly utilizes photoactive material modified planar indium tin oxides (ITOs) to obtain photocurrent responses for the measurement of analytes in solution. In this work, a CdS quantum dot (QD) modified nanopipette was prepared for the PEC analysis of the alkaline phosphatase (ALP) activity in single MCF-7 cells. The nanopipette was filled with ascorbic acid 2-phosphate (AAP) that was egressed outside the nanopipette by electrochemical pumping. Next, AAP was catalyzed by ALP to generate ascorbic acid (AA), which is an efficient electron donor for CdS QDs under illumination. Based on the result that the nanopipette showed a linear photocurrent response to AA, a nearly linear correlation between the photocurrent and the activity of ALP was established. Accordingly, using these CdS QD modified nanopipettes, the ALP activity in single MCF-7 cells was determined to be 0.12 U mL−1 by PEC analysis. This work does not expand the application of PEC bioanalysis, but offers a new strategy for single cell analysis. [ABSTRACT FROM AUTHOR]

Drop-on-demand microkits with a diameter of ∼20 μm are used to measure the activity of acetylcholinesterase (AChE) in a brain slice with single-cell resolution. The relative standard deviation from 25 cellular regions reached 73.3% exhibiting the difference of enzyme activity in the brain slice. Therefore, this approach utilizing the well-established kits provides an alternative single-cell-resolved strategy for the elucidation of enzymatic heterogeneity at the tissue level. [ABSTRACT FROM AUTHOR]

Potassium-selective polymer dots (K-Pdots) containing potassium ionophores were for the first time used for photoelectrochemical (PEC) analysis and yielded sensitive and specific detection of potassium ions. The successful PEC analysis using ion-selective Pdots underscored the effectiveness of the strategy deployed and suggested the potential universality of this strategy for the detection of metal ions, which should advance the development of PEC sensors in ion analysis. [ABSTRACT FROM AUTHOR]

Upconverting ion-selective nanoparticles that emit light at the near-infrared region are prepared here. The transport of calcium ions induces the deprotonation of the incorporated chromoionophore (P6) through ion exchange resulting in an increase in the emission of UCNPs for the detection of intracellular calcium ions. [ABSTRACT FROM AUTHOR]

The molecular profiling of single axons and dendrites in living neurons could provide important information for the better understanding of neuron function. Here, electrosyringe-assisted electrospray mass spectrometry (MS) is established for the first time to achieve intracellular sampling from one axon or dendrite in living neurons for mass spectrometric analysis. The key is the insertion of a ∼130 nm capillary tip into one axon or dendrite to load the cytosol through electro-osmotic flow. The ionization efficiency from the nano-capillary is enhanced to guarantee mass spectrometric analysis of multiple components from the axon and dendrite. Higher levels of pyroglutamic acid and glutamic acid are revealed in the axon compared to in the body and dendrite. This uneven distribution is in accordance with the accumulation of neurotransmitters in the axon for information delivery. The achievement of electrosyringe-assisted electrospray MS is to unveil the molecular distribution in the whole living neuron, which offers the feasibility to deeply investigate molecular communication between the axon/dendrite and the body inside neurons. [ABSTRACT FROM AUTHOR]

A boronic acid functionalized aza-borondipyrromethene dye (azaBDPBA) was applied to the dual-wavelength detection of hydrogen peroxide with high selectivity, which was loaded into cells to indicate the alteration of intracellular hydrogen peroxide during biological processes. [ABSTRACT FROM AUTHOR]

A class of squaramide-based tripodal molecules was employed as new ionophores for highly sensitive and selective sulfate-selective sensors. Compared with the reported tripodal ionophore with urea, squaramide groups as superior hydrogen bonding donor were introduced into the tripodal structure to obtain new ionophores leading to better electrode performance. Three derivatives with unsubstituted (I), p-carbon trifluoride (II), and p-nitro (III) phenyl groups were attached to squaramide groups for the optimization of ionophore based sensors. Electron withdrawing p-nitrophenyl groups gave a greater enhancement of the hydrogen bond donor ability of squaramide so that Ionophore III was chosen as the best candidate for sulfate ion recognition. Such a membrane with 30 mol% TDMACl exhibited a Nernstian slope of −30.2 mV per decade to sulfate ions with a linear range from 1 μM to 100 mM in potentiometric measurement. The selectivity coefficients of the proposed sensor over H2PO4−, Cl−, Br−, NO3−, SCN−, I− and ClO4− were −4.3, −3.4, −2.5, −0.6, +3.1, +3.4 and +5.9, respectively, which were much better than the existing sulfate-selective sensors. The new sensors with high selectivity were successfully applied for the quantification of sulfate in cell lysates and drinking water with good recoveries. [ABSTRACT FROM AUTHOR]

A single-cell assay was developed to measure the activation of phosphoinositide 3-kinase (PI3K) using microanalytical chemical separations and a fluorescently labeled lipid substrate. Phosphatidyl-inositol 4,5 bisphosphate labeled on its acyl chain with Bodipy fluorescein (Bodipy Fl PIP2) was utilized as a substrate for both in vitroand cell-based assays. Detection limits for the substrate and product of the PI3K reaction were 10 to 20 zeptomol. In vitroassays with PI3K with and without pharmacologic inhibitors demonstrated that Bodipy Fl PIP2was converted to phosphatidyl-inositol 3,4,5 trisphosphate (Bodipy Fl PIP3). Bodipy Fl PIP3could be back converted to Bodipy Fl PIP2by the phosphatase PTEN. When Bodipy Fl PIP2was added to a cell lysate, 1.4 fmol of the Bodipy Fl PIP3were produced per ng of protein in the cytoplasmic extract in 10 min. Addition of Bodipy Fl PIP3to a cell lysate yielded 3 fmol of Bodipy Fl PIP2per ng of protein in 8 min. Both Bodipy Fl PIP2and Bodipy Fl PIP3were measureable in single cells and the two species could be inter-converted. Under the appropriate conditions, a fluorescent diacylglycerol was also detected in single cells. When the FcR1 receptor on the cells loaded with the fluorescent lipid was cross-linked, the amount of Bodipy Fl PIP3generated per cell increased 4-fold over that of unstimulated cells. This production of Bodipy Fl PIP3was blocked by wortmannin. Chemical cytometry utilizing the fluorescent lipids will be of value in understanding lipid metabolism at the single-cell level. [ABSTRACT FROM AUTHOR]