Smart Target-Initiated Catalytic DNA Junction Circuit Amplification Strategy for the Ultrasensitive Electrochemiluminescence Detection of MicroRNA.

One of the highly attractive research directions in the electrochemiluminescence (ECL) field is how to regulate and improve ECL efficiency. Quantum dots (QDs) are highly promising ECL materials due to their adjustable luminescence size and strong luminous efficiency. MoS2 NSs@QDs, an ECL emitter, is synthesized via hydrothermal methods, and its ECL mechanism is investigated using cyclic voltammetry and ECL-potential curves. Then, a stable and vertical attachment of a triplex DNA (tsDNA) probe to the MoS2 nanosheets (NSs) is applied to the electrode. Next, an innovative ECL sensor is courageously empoldered for precise and ultrasensitive detection of target miRNA-199a through the agency of ECL-resonance energy transfer (RET) strategy and a dextrous target-initiated catalytic three-arm DNA junction assembly (CTDJA) based on a toehold strand displacement reaction (TSDR) signal amplification approach. Impressively, the ingenious system not only precisely regulates the distance between energy donor-acceptor pairs leave energy less loss and more ECL-RET efficiency, but also simplifies the operational procedure and verifies the feasibility of this self-assembly process without human intervention. This study can expand MoS2 NSs@QDs utilization in ECL biosensing applications, and the proposed nucleic acid amplification strategy can become a miracle cure for ultrasensitive detecting diverse biomarkers, which helps researchers to better study the tumor mechanism, thereby unambiguously increasing cancer cure rates and reducing the risk of recurrence.

An in situ growth approach to the fabrication of zeolite imidazolate framework-90 bonded capillary column for gas chromatography separation.

The unique properties of metal-organic frameworks, such as diversity in structures and pore sizes, high surface area, shape selectivity and available to functionality make them as potential materials of the stationary phase for gas chromatography. Here we show an in situ growth approach to the fabrication of zeolite imidazolate framework-90 (ZIF-90) bonded capillary column for gas chromatography separation. ZIF-90 was directly grown onto the inner wall of the carboxyl modified capillary via the coordination between Zn(II) and carboxyl group. The fabricated ZIF-90 bonded capillary column acted as a weak polar stationary phase. It not only exhibits high capacity in the separation of linear molecules, but also offers excellent features for the separation of 2- and 3-substituted ketones.

Room-temperature phosphorescent discrimination of catechol from resorcinol and hydroquinone based on sodium tripolyphosphate capped Mn-doped ZnS quantum dots.

A room-temperature phosphorescence (RTP) strategy was developed for direct, additive-free discrimination of catechol from resorcinol and hydroquinone based on sodium tripolyphosphate capped Mn-doped ZnS quantum dots (STPP-Mn-ZnS QDs). The RTP response of STPP-Mn-ZnS QDs to the three isomers was pH-dependent, and the greatest difference in the RTP response to the isomers was observed at pH 8.0: catechol enhanced the RTP intensity of the QDs, while resorcinol and hydroquinone had little effect on the RTP intensity of the QDs. The enhanced RTP intensity of 1 µM catechol was not affected by the coexistence of 30 µM resorcinol and 50 µM hydroquinone at pH 8.0. The detection limit of this RTP method was 53 nM catechol, and the precision was 3.2% (relative standard deviation) for five replicate detections of 1 µM catechol. The discrimination mechanism was ascribed to the weak bonded ligand of STPP-Mn-ZnS QDs and the different interaction between the three isomers and STPP-Mn-ZnS QDs. The strong binding of catechol to Zn resulted in the extraction of Zn from the surface of STPP-Mn-ZnS QDs and the generation of holes that were trapped by Mn(2+) to form Mn(3+). Catechol also promoted the reduction of Mn(3+) into Mn(2+) excited state, thus ultimately inducing the enhanced RTP response of STPP-Mn-ZnS QDs.

Intra-brachial ergonovine, not acetylcholine, is associated with radial artery vasospasm in patients with coronary vasospasm.

BACKGROUND: The intracoronary provocation test is expensive and may cause complications. Therefore, we investigated the sensitivity, specificity and safety of different drug- and dose-peripheral artery provocation tests in the diagnosis of coronary artery spasm (CAS). METHODS: The patients who had repeated chest pain as well as both coronary and radial stenoses <50% were selected. These patients were divided into CAS group (n = 24) and control group (n = 33) after the intracoronary ergonovine provocation test. All patients underwent radial artery provocation tests at different dose-acetylcholine (200 µg, 400 µg and 800 µg) and ergonovine (60 µg, 100 µg and 160 µg). The predictive values of radial provocation tests for CAS diagnosis were analysed using receiver operator characteristic (ROC) curves. RESULTS: In radial acetylcholine provocation tests, 200 µg of acetylcholine failed to induce radial artery spasm, and the radial artery stenosis degree was not significantly different between the CAS group and control group at 400 µg and 800 µg of acetylcholine (all p > 0.05). In the radial artery ergonovine provocation tests, the radial artery stenosis degree was all significantly higher in the CAS group than in the control group at the three different doses (all p < 0.05). The specificity and sensitivity of radial ergonovine provocation tests were 90.91% and 50.00% at 60 µg, 96.97% and 66.67% at 100 µg, and 90.91% and 95.83% at 160 µg. Only the radial 160 µg-ergonovine provocation test caused CAS in one case. CONCLUSION: The radial acetylcholine provocation test has no diagnostic value for CAS. The radial 160 µg-ergonovine provocation test has higher sensitivity and specificity for CAS diagnosis, but its safety should be paid attention to.

Ascorbic acid induced enhancement of room temperature phosphorescence of sodium tripolyphosphate-capped Mn-Doped ZnS quantum dots: mechanism and bioprobe applications.

Although quantum dot (QD)-based room temperature phosphorescence (RTP) probes are promising for practical applications in complex matrixes such as environmental, food and biological samples, current QD-based-RTP probes are not only quite limited but also exclusively based on the RTP quenching mechanism. Here we report an ascorbic acid (AA) induced phosphorescence enhancement of sodium tripolyphosphate-capped Mn-doped ZnS QDs, and its application for turn-on RTP detection. The chelating ability allows AA to extract the Mn and Zn from the surface of the QDs and to generate more holes which are subsequently trapped by Mn(2+), while the reducing property permits AA to reduce Mn(3+) to Mn(2+) in the excited state, thereby enhancing the excitation and orange emission of the QDs. The enhanced RTP intensity of the QDs increases linearly with the concentration of AA in the range of 0.05-0.8 µM. Thus, a QD-based RTP probe for AA is developed. The proposed QD-based turn-on RTP probe avoids tedious sample pretreatment, and offers good sensitivity and selectivity for AA in the presence of the main relevant metal ions and other molecules in biological fluids. The limit of detection (3s) of the developed method is 9 nM AA, and the relative standard deviation is 4.8 % for 11 replicate detections of 0.1 µM AA. The developed method is successfully applied to the analysis of real samples of human urine and plasma for AA with quantitative recoveries from 96 to 105 %.

Ru(bpy)32+-Silica@Poly-L-lysine-Au as labels for electrochemiluminescence lysozyme aptasensor based on 3D graphene.

In this work, the feasibility of a novel sensitive electrochemiluminescence aptasensor for the detection of lysozyme using Ru(bpy)32+-Silica@Poly-L-lysine-Au (RuSiNPs@PLL-Au) nanocomposites labeling as an indicator was demonstrated. The substrate electrode of the aptasensor was prepared by depositing gold nanoparticles (AuNPs) on 3D graphene-modified electrode. The lysozyme binding aptamer (LBA) was attached to the 3D graphene/AuNPs electrode through gold-thiol affinity, hybridized with a complementary single-strand DNA (CDNA) of the lysozyme aptamer labeled by RuSiNPs@PLL-Au as an electrochemiluminescence intensity amplifier. Thanks to the synergistic amplification of the 3D graphene, the AuNPs and RuSiNPs@PLL-Au NPs linked to Ru(bpy)32+-ECL further enhanced the ECL intensity of the aptasensor. In presence of lysozyme, the CDNA segment of the self-assembled duplex was displaced by the lysozyme, resulting in decreased electrochemiluminescence signal. Under the optimized conditions, the decrease in electrochemiluminescence intensity varied proportionally with the logarithmic concentration of the lysozyme from 2.25 × 10-12 to 5.0 × 10-8 mol L-1, and the detection limit was estimated to 7.5 × 10-13 mol L-1. The aptasensor was further tested in real samples and found reliable for the detection of lysozyme, thus holding great potential application in food safety researches and bioassay analysis.

Fabrication of metal-organic framework MIL-88B films on stainless steel fibers for solid-phase microextraction of polychlorinated biphenyls.

Metal-organic frameworks (MOFs) have received considerable attention as novel sorbents for sample preparation due to their fascinating structures and functionalities such as large surface area, good thermal stability, and uniform structured nanoscale cavities. Here, we report the application of a thermal and solvent stable MOF MIL-88B with nanosized bipyramidal cages and large surface area for solid-phase microextraction (SPME) of polychlorinated biphenyls (PCBs). Novel MIL-88B coated fiber was fabricated via an in situ hydrothermal growth of MIL-88B film on etched stainless steel fiber. The MIL-88B coated fiber gave large enhancement factors (757-2243), low detection limits (0.45-1.32ngL(-1)), and good linearity (5-200ngL(-1)) for PCBs. The relative standard deviation (RSD) for six replicate extractions of PCBs at 100ngL(-1) on MIL-88B coated fiber ranged from 4.2% to 8.7%. The recoveries for spiked PCBs (10ngL(-1)) in water and soil samples were in the range of 79.7-103.2%. Besides, the MIL-88B coated fiber was stable enough for 150 extraction cycles without significant loss of extraction efficiency. The developed method was successfully applied to the determination of PCBs in water samples and soil samples.