Direct Visualization of Dark Interlayer Exciton Transport in Moiré Superlattices.

Moiré superlattices have emerged as an unprecedented manipulation tool for engineering correlated quantum phenomena in van der Waals heterostructures. With moiré potentials as a naturally configurable solid-state that sustains high exciton density, interlayer excitons in transition metal dichalcogenide heterostructures are expected to achieve high-temperature exciton condensation. However, the exciton degeneracy state is usually optically inactive due to the finite momentum of interlayer excitons. Experimental observation of dark interlayer excitons in moiré potentials remains challenging. Here we directly visualize the dark interlayer exciton transport in WS2/h-BN/WSe2 heterostructures using femtosecond transient absorption microscopy. We observe a transition from classical free exciton gas to quantum degeneracy by imaging temperature-dependent exciton transport. Below a critical degeneracy temperature, exciton diffusion rates exhibit an accelerating downward trend, which can be explained well by a nonlinear quantum diffusion model. These results open the door to quantum information processing and high-precision metrology in moiré superlattices.

Interfacial Conductor-Modulated Low-Triggered Potential Electrochemiluminescence from Conjugated Polymers for Bioanalysis.

Polyfluorene and its derivatives (PFs) are extremely appealing electrochemiluminescence (ECL) illuminants thanks to their easy modification, high quantum yield, excellent photostability, and nontoxicity, exhibiting great application potential in ECL sensing and imaging. Unfortunately, most reported PFs-based ECL bioanalysis generally exhibited high triggering potential (>1.0 V vs Ag/AgCl), which introduced undesirable electrochemical interference to adversely affect the sensitivity and accuracy of biological analysis. This work innovatively exploited poly(3,4-ethylenedioxythiophene) (PEDOT) as an interfacial conductor to modulate the low ECL triggering potential of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3}-thiadazole)] (PFBT) nanoparticles (NPs). The unique conductivity of in situ electrodeposited PEDOT promoted electron transfer between PFBT NPs and coreactant tripropylamine (TPrA), negatively shifting the ECL triggering potential of PFBT NPs from +1.22 to +0.78 V. The PFBT NPs/PEDOT coupled the localized hybridization chain reaction (LHCR) circuits to achieve a specific and sensitive ECL detection of malathion (MAL), and a low limit of detection (LOD) of 22 fg/mL was obtained. The interfacial conductor provides inspiration for creating the low ECL triggering potential. PFBT NPs-coupled PEDOT builds a low ECL triggering potential of the PFs-based platform for pesticide residue analysis with low interference and high sensitivity.

Dual-Function DNA Nanowires with Self-Feedback Amplification and Efficient Signal Transduction for Intracellular Imaging of MicroRNA-155.

Intracellular detection and imaging of microRNAs (miRNAs) with low expression usually face the problem of unsatisfactory sensitivity. Herein, a novel dual-function DNA nanowire (DDN) with self-feedback amplification and efficient signal transduction was developed for the sensitive detection and intracellular imaging of microRNA-155 (miRNA-155). Target miRNA-155 triggered catalytic hairpin assembly (CHA) to generate plenty of double-stranded DNA (dsDNA), and a trigger primer exposed in dsDNA initiated a hybridization chain reaction (HCR) between four well-designed hairpins to produce DDN, which was encoded with massive target sequences and DNAzyme. On the one hand, target sequences in DDN acted as self-feedback amplifiers to reactivate cascaded CHA and HCR, achieving exponential signal amplification. On the other hand, DNAzyme encoded in DDN acted as signal transducers, successively cleaving Cy5 and BHQ-2 labeled substrate S to obtain a significantly enhanced fluorescence signal. This efficient signal transduction coupling self-feedback amplification greatly improved the detection sensitivity with a limit of detection of 160 aM for miRNA-155, enabling ultrasensitive imaging of low-abundance miRNA-155 in living cells. The constructed DDN creates a promising fluorescence detection and intracellular imaging platform for low-expressed biomarkers, exhibiting tremendous potential in biomedical studies and clinical diagnosis of diseases.

Porous Complex-Mediated Dual Emission of Porphyrins for the Electrochemiluminescence Bioassay.

Although porphyrins make up a promising class of electrochemiluminescence (ECL) luminophors, their aggregation-caused quenching (ACQ) characteristics lead to inferior ECL efficiency (ΦECL). Furthermore, current application of porphyrins is limited to cathodic emission. This work creatively exploited a cage-like porous complex (referred to as SWU-1) as the microreactor to recede the ACQ effect while modulating dual ECL emission of meso-tetra(4-carboxyphenyl)porphine (TCPP), which self-assembled with SWU-1 to form TCPP@SWU-1 nanocapsules (TCPP@SWU-1 NCs). As the microreactor, SWU-1 not only effectively constrained TCPP aggregation to improve electron-hole recombination efficiency but also improved stability of anion and cation radicals, thus significantly enhancing the dual emission of TCPP. Compared with TCPP aggregates, the resulting TCPP@SWU-1 NCs exhibited significantly enhanced anodic and cathodic emission, and their ΦECL was increased by 8.7-fold and 3.9-fold, respectively. Furthermore, black hole quencher-2 (BHQ2) can simultaneously quench anodic and cathodic signals. TCPP@SWU-1 NCs coupling BHQ2 conveniently achieved an ECL ratio detection of miRNA-126, and the limit of detection (S/N = 3) was 4.1 aM. This work pioneered the development of the cage-like porous complex SWU-1 as the microreactor to alleviate defects of the ACQ effect and mediate dual emission of TCPP. The coupling of dual-emitting TCPP@SWU-1 NCs and dual-function moderator BHQ2 created a novel single-luminophor-based ratio system for bioanalysis and provided a promising ECL analysis approach for miRNA-126.

Host-Guest Recognition-Mediated Supramolecular Aggregation-Induced Electrochemiluminescence of Iridium(III) Complexes for Nucleic Acid Bioassay.

Currently reported aggregation-induced electroluminescence (AIECL) is usually based on the electrostatic integration of luminous monomers, and its application is still limited by the low ECL efficiency and poor structural stability of electrostatic integration-based AIECL emitters. Herein, host-guest recognition-mediated supramolecular AIECL was creatively developed to overcome the defects of electrostatic-integration-based AIECL. Cucurbit[8]uril (CB[8]) as the host recognized tris (2-phenylpyridine) iridium(III) [Ir(ppy)3] as the guest to form a novel supramolecular complex Ir-CB[8]. CB[8] can not only provide a large hydrophobic cavity to efficiently load Ir(ppy)3 and enrich coreactant tripropylamine but also utilize its carbonyl-laced portals to form intramolecular hydrogen bonds to stabilize the supramolecular structure, so Ir-CB[8] revealed excellent AIECL performance. The AIECL emitter Ir-CB[8] coupled the efficient DNA walker to construct a sensing system for miRNA-16 detection. Au nanoparticles@norepinephrine (AuNPs@NE) trapped by single-strand S1 was developed to significantly quench the ECL emission of Ir-CB[8]. When the target microRNA-16 (miRNA-16) existed, H1 was opened and the sequential assembly from H2 to H7 was triggered, forming "windmill"-like DNA walker with six Pb2+-dependent leg DNA. The assembled DNA walker, which was centered on DNA structure, had high efficiency and biocompatibility and can cut S1 to keep the DNA fragment-carrying quencher AuNPs@NE away from the electrode surface, thus restoring the ECL emission of Ir-CB[8] and realizing ultrasensitive detection of miRNA-16. Supramolecular AIECL mediated by host-guest recognition provides a new way for constructing AIECL emitters with excellent structural stability and AIECL efficiency, and an Ir-CB[8] coupling "windmill"-like DNA walker builds a promising ECL-sensing system for bioassay.

CRISPR/Cas12a-Mediated Aptasensor Based on Tris-(8-hydroxyquinoline)aluminum Microcrystals with Crystallization-Induced Enhanced Electrochemiluminescence for Acetamiprid Analysis.

Improving the electrochemiluminescence (ECL) efficiency of luminophores has always been the goal of the ECL field. Herein, a novel crystallization-induced enhanced ECL (CIE ECL) strategy was exploited to significantly enhance the ECL efficiency of metal complex tris-(8-hydroxyquinoline)aluminum (Alq3). Alq3 monomers self-assembled and directionally grew to form Alq3 microcrystals (Alq3 MCs) in the presence of sodium dodecyl sulfate. The highly ordered crystal structure of Alq3 MCs not only constrained the intramolecular rotation of Alq3 monomers to decrease nonradiative transition but also accelerated the electron transfer between Alq3 MCs and coreactant tripropylamine to increase radiative transition, thus leading to a CIE ECL effect. Alq3 MCs exhibited brilliant anode ECL emission, which was 210-fold stronger than that of Alq3 monomers. The exceptional CIE ECL performance of Alq3 MCs coupled the efficient trans-cleavage activity of CRISPR/Cas12a assisted by rolling circle amplification and catalytic hairpin assembly to fabricate a CRISPR/Cas12a-mediated aptasensor for acetamiprid (ACE) detection. The limit of detection was as low as 0.79 fM. This work not only innovatively exploited a CIE ECL strategy to enhance the ECL efficiency of metal complexes but also integrated CRISPR/Cas12a with a dual amplification strategy for the ultrasensitive monitoring of pesticides such as ACE.

Nickel Single-Atom Catalyst Boosts Electrochemiluminescence of Graphitic Carbon Nitride for Sensitive Detection of HBV DNA.

Owing to excellent catalytic activity, single-atom catalysts (SACs) have recently attracted considerable research interest in the electrochemiluminescence (ECL) field. However, the applications of SACs are mostly limited to conventional luminol ECL system. Hence, it is necessary to explore the application of SACs in more ECL systems. In this work, nickel single-atom catalysts (Ni SACs) were successfully applied in the graphitic carbon nitride (g-C3N4)-H2O2 ECL system to significantly enhance its cathodic emission. Notably, g-C3N4 acted not only as an ECL luminophore but also as a support to anchor Ni SACs. Ni SACs can significantly activate H2O2 to produce abundant OH• radicals for enhancing the cathodic ECL emission of g-C3N4. Ni SACs-anchored g-C3N4 (Ni SACs@g-C3N4) had a 10-fold enhanced ECL intensity as compared to g-C3N4. Finally, the Ni SACs@g-C3N4-H2O2 ECL system was developed to detect hepatitis B virus (HBV) DNA by incorporating an entropy-driven DNA walking machine-assisted CRISPR-Cas12a amplification strategy. The constructed biosensor exhibited excellent detection performance for HBV DNA with a limit of detection as low as 17 aM. This work puts forward a new idea for enhancing the cathodic ECL of g-C3N4-H2O2 and expands the application of SACs in the ECL system.

Transfer RNA-derived fragment 5'tRF-Gly promotes the development of hepatocellular carcinoma by direct targeting of carcinoembryonic antigen-related cell adhesion molecule 1.

Transfer RNA-derived fragments are a group of small noncoding single-stranded RNA that play essential roles in multiple diseases. However, their biological functions in carcinogenesis are not well understood. In this study, 5'tRF-Gly was found to have significantly high expression in hepatocellular carcinoma (HCC), and the upregulation of 5'tRF-Gly was positively correlated with tumor size and tumor metastasis. Overexpression of 5'tRF-Gly induced increased growth rate and metastasis in HCC cells in vitro and in nude mice, while knockdown showed the opposite effect. Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) was confirmed to be a direct target of 5'tRF-Gly in HCC. In addition, the cytological effect of CEACAM1 knockdown proved to be similar to the overexpression of 5'tRF-Gly. Moreover, attenuation of CEACAM1 expression rescued the 5'tRF-Gly-mediated promoting effects on HCC cells. These data show that 5'tRF-Gly is a new tumor-promoting factor and could be a potential diagnostic biomarker or new therapeutic target for HCC.

Dynamic 3D DNA Rolling Walkers via Directional Movement on a Lipid Bilayer Supported by Au@Fe3O4 Nanoparticles for Sensitive Detection of MiRNA-16.

Currently reported polyfluorene-based fluorescence detection usually shows high background signal and low detection sensitivity. This work developed a novel three-dimensional (3D) DNA rolling walker via directional movement on a lipid bilayer (LB) supported by Au@Fe3O4 nanoparticles (NPs) in a polyfluorene-based fluorescence system so that it could achieve significantly improved detection sensitivity and almost zero-background signal detection for miRNA-16. First, the carboxyl-functionalized poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3}-thiadazole)] polymer nanoparticles (c-PFBT PNPs) covalently bonded with amino-labeled single-strand CP and further hybridized with single-strand AP to prepare AP-CP-coupled c-PFBT PNP probes. Meanwhile, Au@Fe3O4 NPs were developed as efficient fluorescence quenchers and served as the matrix for assembling the LB. The resulting Au@Fe3O4@LB assembled cholesterol-labeled orbital DNA L1 and L2 and further assembled hairpins H1 and AP-CP-coupled c-PFBT PNP probes to construct DNA nanomachines. Then, the target miRNA-16 was introduced to initiate the rolling circle amplification (RCA) reaction and form dynamic DNA rolling walkers, thus releasing single-strand CP-coupled c-PFBT PNP probes. The magnetic separation effect of Au@Fe3O4 NPs made it possible to detect the fluorescence signal from the released probes, thus achieving almost zero-background signal detection for miRNA-16 with a low detection limit of 95 aM. The flexible interfaces provided by the LB endowed the DNA rolling walkers with high binding efficiency and low derailment probability, thus achieving significantly improved detection sensitivity. The developed strategy provided an attractive polyfluorene-based fluorescence platform with high-sensitivity and low-background signals.

Hydrophobic Localized Enrichment of Co-reactants to Enhance Electrochemiluminescence of Conjugated Polymers for Detecting SARS-CoV-2 Nucleocapsid Proteins.

The enrichment of co-reactants is one of the keys to improving the sensitivity of electrochemiluminescence (ECL) detection. This work developed a novel hydrophobic localized enrichment strategy of co-reactants utilizing the inner hydrophobic cavity of ß-cyclodextrin (ß-CD). Pt nanoparticles (Pt NPs) were grown in situ on the coordination sites for metal ions of ß-CD to prepare the ß-CD-Pt nanocomposite, which could not only enrich co-reactant 3-(dibutylamino) propylamine (TDBA) highly efficiently through its hydrophobic cavity but also immobilize TDBA via the Pt-N bond. Meanwhile, the carboxyl-functionalized poly[2,5-dioctyl-1,4-phenylene] (PDP) polymer nanoparticles (PNPs) were developed as excellent ECL luminophores. With SARS-CoV-2 nucleocapsid protein (ncovNP) as a model protein, the TDBA-ß-CD-Pt nanocomposite combined PDP PNPs to construct a biosensor for ncovNP determination. The PDP PNPs were modified onto the surface of a glassy carbon electrode (GCE) to capture the first antibody (Ab1) and further capture antigen and secondary antibody complexes (TDBA-ß-CD-Pt@Ab2). The resultant biosensor with a sandwich structure achieved a highly sensitive detection of ncovNP with a detection limit of 22 fg/mL. TDBA-ß-CD-Pt shared with an inspiration in hydrophobic localized enrichment of co-reactants for improving the sensitivity of ECL detection. The luminophore PDP PNPs integrated TDBA-ß-CD-Pt to provide a promising and sensitive ECL platform, offering a new method for ncovNP detection.

Hippocampal microRNA-26a-3p deficit contributes to neuroinflammation and behavioral disorders via p38 MAPK signaling pathway in rats.

BACKGROUND: Neuronal injury is considered a critical risk factor in the pathogenesis of most neurological and neuropsychiatric diseases. However, the underlying molecular mechanisms and identification of potential therapeutic targets for preventing neuronal injury associated with brain function remain largely uncharacterized. Therefore, identifying neural mechanisms would put new insights into the progression of this condition and provide novel therapeutic strategies for the treatment of these diseases. METHODS: Stereotactic injection of AAV virus was used to knock-down the miR-26a-3p within hippocampus of rats. Behavioral changes was detected by open field test (OFT), elevated plus maze (EPM), forced swim test (FST) and sucrose preference test (SPT). The inflammatory cytokines and related proteins were verified by real-time quantitative PCR, immunoblotting or immunofluorescence assay. Golgi staining and electron microscopy analysis was used to observe the dendritic spine, synapse and ultrastructural pathology. SB203580 (0.5 mg/kg) were administered daily to prevent p38 MAPK via an intraperitoneal (i.p.) injection. Finally, electrophysiological method was used to examine the synaptic transmission via whole-cell patch-clamp recording. RESULTS: Here, we showed that miR-26a-3p deficiency within hippocampal regions leads to the activation of microglia, increased level of pro-inflammatory cytokines and behavioral disorders in rats, effects which appear to be mediated by directly targeting the p38 mitogen-activated protein kinase (MAPK)-NF-κB signaling pathway. Specifically, we found that the enhanced glia-activation may consequently result in neuronal deterioration that mainly presented as the dysregulation of structural and functional plasticity in hippocampal neurons. In contrast, preventing p38 pathway by SB203580 significantly ameliorated abnormal behavioral phenotypes and neuronal jury resulting from miR-26a-3p knock-down. CONCLUSION: These results suggest that the normal expression of miR-26a-3p exerts neuroprotective effects via suppressing neural abnormality and maintaining neuroplasticity to against behavioral disorders in rats. These effects appear to involve a down-regulation of p38 MAPK-NF-κB signaling within the hippocampal region. Taken together, these findings provide evidence that miR-26a-3p can function as a critical factor in regulating neural activity and suggest that the maintaining of normal structure and function of neurons might be a potential therapeutic strategy in the treatment of neurological disorders.

Novel Ratiometric Electrochemiluminescence Biosensor Based on BP-CdTe QDs with Dual Emission for Detecting MicroRNA-126.

The electrochemiluminescence (ECL) ratiometric assay is usually based on two different ECL luminophores, and the choice of two suitable luminophores and shared co-reactant makes its construction challenging. The single-emitter-based ECL ratio mode could overcome the limitation of two luminophores and simplify the construction process, so it is an ideal choice. In this work, CdTe quantum dots (CdTe QDs) were modulated using black phosphorus (BP) nanosheet to simultaneously emit the cathodic and anodic ECL signals, and H2O2 and tripropylamine (TPrA) served as the cathodic and anodic co-reactants, respectively. MicroRNA-126 (miRNA-126) was selected as the template target to exploit the application of BP-CdTe QDs in the single-emitter-based ECL ratio detection. Through the target recycling triggering rolling-circle amplification (RCA) reaction, a large amount of glucose oxidase (GOx)-modified single strand 1 was introduced. GOx catalyzed glucose to produce H2O2 in situ, which acted as a dual-role moderator to quench the anodic ECL emission with TPrA as the co-reactant while enhancing the cathodic emission, thereby realizing the ratiometric detection of miRNA-126 with a low detection limit of 29 aM (S/N = 3). The dual-ECL-emitting BP-CdTe QDs with TPrA-H2O2 as dual co-reactant provide a superior ECL ratio platform involving enzyme catalytic reaction, expanding the application of single-emitter-based ratio sensing in the diverse biological analysis.

Bifunctional Moderator-Powered Ratiometric Electrochemiluminescence Enzymatic Biosensors for Detecting Organophosphorus Pesticides Based on Dual-Signal Combined Nanoprobes.

The bifunctional moderator is urgently needed in the field of ratiometric electrochemiluminescence (ECL) sensing since it can mediate simultaneously two ECL signals to conveniently realize their opposite change trend. This work designed a novel dual-signal combined nanoprobe with carboxyl-functionalized poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3}-thiadazole)] nanoparticles (c-PFBT NPs) as the anodic ECL probe and L-cysteine capped CdS quantum dots (L-CdS QDs) as the cathodic ECL probe, which performed a dual-signal output capability without any additional coreactants. More importantly, hydrogen peroxide (H2O2) produced in situ by enzyme-catalyzed reaction was developed as a bifunctional moderator for simultaneously regulating two signals. The dual-signal combined nanoprobe (c-PFBT NPs@CdS QDs) served as the matrix to immobilize acetylcholinesterase (AChE) and choline oxidase for organophosphorus (OPs) analysis. In the absence of OPs, H2O2 was produced by catalyzing the substrate acetylthiocholine (ATCl) with enzymes and it quenched the anodic ECL signal from c-PFBT NPs and simultaneously promoted the cathodic ECL signal from L-CdS QDs. When OPs was present, the activity of AChE was inhibited, the anodic signal would increase, and the cathodic signal would accordingly decrease. The integration of the bifunctional moderator H2O2 and dual-signal combined nanoprobe c-PFBT NPs@CdS QDs not only provides an attractive ECL platform for enzymatic sensing involving the generation or consumption of H2O2 but also paves a new pathway for other ratiometric ECL systems involving enzyme catalytic amplification for detecting antigens, antibodies, DNA, RNA, etc.

MicroRNA-204-5p reduction in rat hippocampus contributes to stress-induced pathology via targeting RGS12 signaling pathway.

BACKGROUND: Neuroinflammation occupies a pivotal position in the pathogenesis of most nervous system diseases, including depression. However, the underlying molecular mechanisms of neuroinflammation associated with neuronal injury in depression remain largely uncharacterized. Therefore, identifying potential molecular mechanisms and therapeutic targets would serve to better understand the progression of this condition. METHODS: Chronic unpredictable stress (CUS) was used to induce depression-like behaviors in rats. RNA-sequencing was used to detect the differentially expressed microRNAs. Stereotactic injection of AAV virus to overexpress or knockdown the miR-204-5p. The oxidative markers and inflammatory related proteins were verified by immunoblotting or immunofluorescence assay. The oxidative stress enzyme and products were verified using enzyme-linked assay kit. Electron microscopy analysis was used to observe the synapse and ultrastructural pathology. Finally, electrophysiological recording was used to analyze the synaptic transmission. RESULTS: Here, we found that the expression of miR-204-5p within the hippocampal dentate gyrus (DG) region of rats was significantly down-regulated after chronic unpredicted stress (CUS), accompanied with the oxidative stress-induced neuronal damage within DG region of these rats. In contrast, overexpression of miR-204-5p within the DG region of CUS rats alleviated oxidative stress and neuroinflammation by directly targeting the regulator of G protein signaling 12 (RGS12), effects which were accompanied with amelioration of depressive-like behaviors in these CUS rats. In addition, down-regulation of miR-204-5p induced neuronal deterioration in DG regions and depressive-like behaviors in rats. CONCLUSION: Taken together, these results suggest that miR-204-5p plays a key role in regulating oxidative stress damage in CUS-induced pathological processes of depression. Such findings provide evidence of the involvement of miR-204-5p in mechanisms underlying oxidative stress associated with depressive phenotype.

Lipin1 mediates cognitive impairment in fld mice via PKD-ERK pathway.

Lipin1 is important in lipid synthesis because of its phosphatidate phosphatase activity, and it also functions as transcriptional coactivators to regulate the expression of genes involved in lipid metabolism. We found that fld mice exhibit cognitive impairment, and it is related to the DAG-PKD-ERK pathway. We used fld mice to explore the relationship between lipin1 and cognitive function. Our results confirmed the presence of cognitive impairment in the hippocampus of lipin1-deficient mice. As shown in behavioral test, the spatial learning and memory ability of fld mice was much worse than that of wild-type mice. Electron microscopy results showed that the number of synapses in hippocampus of fld mice was significantly reduced. BDNF,SYP, PSD95 were significantly reduced. These results suggest that lipin1 impairs synaptic plasticity. Hence,a deficiency of lipin1 leads to decreased DAG levels and inhibits PKD activation, thereby affecting the phosphorylation of ERK and the CREB.

DNA branched junctions induced the enhanced fluorescence recovery of FAM-labeled probes on rGO for detecting Pb2.

The reduced graphene oxide (rGO) could strongly adsorb and quench the fluorescence of dye-labeled single-stranded DNA (ssDNA); thus, it is widely applied in fluorescent sensors. However, these sensors may suffer from a limited sensitivity due to the low fluorescence recovery when adding the complementary DNA (cDNA) sequence. In this work, the powerful DNA branched junctions were constructed to improve the fluorescence recovery of FAM-labeled probe on rGO. In the presence of target Pb2+, the ribonucleotide (rA) in the substrate was cleaved specifically and the catalytic hairpin assembly of three metastable hairpins was further initiated, accompanied by the formation of DNA branched junctions. Then, the liberated Pb2+ could be recyclable. Impressively, the DNA branched junctions not only hybridize with the FAM-labeled probes with a high efficiency, but also are significantly undesirable for the rGO. Thus, a high fluorescence recovery of FAM-labeled probe on rGO was expected. The integration of the high fluorescence recovery and dual-cycle signal amplification endows the sensing strategy with a good performance for Pb2+ detection, including low detection limit (0.17 nM), good selectivity, and satisfactory practical applicability. The proposed DNA branched junctions offer a novel avenue to improve the fluorescence recovery of the dye-labeled probes on rGO for biological analysis.

A novel electrochemiluminescence biosensor based on the self-ECL emission of conjugated polymer dots for lead ion detection.

The poly[(9,9-dioctylfuorenyl-2,7-diyl)-alt-co-(1,4-benzo-{2,1',3}-thiadiazole)] (PFBT) was carboxyl-functionalized to prepare polymer dots (C-PFBT Pdots), which served as a self-ECL emitter for producing an extraordinary ECL signal without any exogenous coreactants. The C-PFBT Pdots-modified electrode captured the substrate DNA and further hybridized with a ferrocene (Fc)-labeled DNA. The ECL emission of C-PFBT Pdots was quenched by Fc (a signal off state). After the DNAzyme was added, the DNAzyme-substrate hybrids were formed through hybridizing between DNAzyme and substrate and the Fc-labeled DNA was released. In the presence of target Pb2+, the DNAzyme-substrate hybrids could be specifically recognized and cleaved to release the DNAzyme and Pb2+. Ultimately, the released DNAzyme would further hybridize with the substrate for producing the DNAzyme-substrate hybrids and then were cleaved by the released Pb2+. As a result, the DNA walking machine was generated and the substantial Fc was away from C-PFBT Pdots to obtain a signal on state. Such a strategy achieved a sensitive detection of Pb2+ and the detection limit was as low as 0.17 pM. Moreover, making this ECL biosensor for an intracellular Pb2+ detecting, a convincing performance was achieved. The self-ECL emitter C-PFBT Pdots combining with the quencher Fc provided a new strategy and platform for constructing a coreactant-free ECL assay.

An electrochemiluminescence biosensor for the detection of soybean agglutinin based on carboxylated graphitic carbon nitride as luminophore.

As an important glycoprotein of the lectin family, soybean agglutinin (SBA) is an anti-nutritional factor with considerable toxic and side effects and plays a significant role in tumor analysis. In order to achieve the sensitive detection of SBA, a sandwich-structured electrochemiluminescence (ECL) biosensor was constructed using carboxylated carbon nitride (C-g-C3N4) as luminophore and D-galactosamine (galM) as a recognition element. A glassy carbon electrode (GCE) was modified with Au nanoparticles (Au NPs) for capturing the galM via Au-N bond, and further capturing the target SBA by specific recognition between galM and SBA. In the presence of SBA, the composite C-g-C3N4-galM was immobilized onto the electrode. With the increase in the concentration of SBA, the ECL signal from C-g-C3N4 increased, thus achieving a signal-on detection of SBA. The linear range of the biosensor was 1.0 ng/mL~10 µg/mL and detection limit for SBA was as low as 0.33 ng/mL. In this construction strategy, C-g-C3N4 not only acted as an excellent signal probe, but also as an immobilization matrix to easily achieve a high loading of the small molecule recognition element galM. This strategy provides a simple alternative SBA detection platform. Graphical abstract.

An ultrasensitive signal-on electrochemiluminescence biosensor based on Au nanoclusters for detecting acetylthiocholine.

For improving the sensitivity of the electrochemiluminescent (ECL) detection and extending the applications of luminophore, the development of coreactant accelerator is one of the important ways. In this work, Au nanoclusters (Au NCs) were chosen as the luminescent material, and thiocholine, which was in situ generated by enzymatic reaction, was found to serve as a coreactant accelerator for Au NC-S2O82- ECL system. Based on this discovery, a highly sensitive detection of acetylthiocholine (ATCl) was achieved using the acetylcholinesterase (AChE) biosensor. CeO2 nanowires (CeO2 NWs) were used to improve the stability of Au NCs on the glassy carbon electrode (GCE) due to the large specific surface area and good film-forming properties of CeO2 NWs. ATCl was catalyzed by acetylcholinesterase (AChE) to produce thiocholine, which served as the coreactant accelerator to improve the ECL signal of Au NC-S2O82- system. The biosensor obtained a low detection limit of 0.17 nM. The integration of thiocholine and Au NCs would provide a new ECL platform for bioanalysis. Graphical abstract ᅟ.

Aberrant Expression of Histamine-independent Pruritogenic Mediators in Keratinocytes may be Involved in the Pathogenesis of Prurigo Nodularis.

Prurigo nodularis is a highly pruritic and hyperplastic chronic dermatosis with unknown pathogenesis. Many pruritogenic mediators, including nerve growth factor, interleukin (IL)-31, thymic stromal lymphopoietin, and endothelin-1, are implicated in chronic itch and inflammation. This study investigated the mRNA levels and immunoreactivity of the nerve growth factor, IL-31, thymic stromal lymphopoietin, and endothelin axes in both lesional and perilesional skin in prurigo nodularis by using quantitative real-time PCR and immunohistochemistry studies. The nerve growth factor high-affinity receptor tyrosine kinase receptor A was upregulated while the low affinity receptor p75 neurotrophin receptor was downregulated in prurigo nodularis lesions. Downregulated expression of IL-31/IL-31 receptor A and endothelin-3/endothelin receptor B and upregulation of thymic stromal lymphopoietin receptor were found in prurigo nodularis lesions. Aberrant expression of nerve growth factor, IL-31, thymic stromal lymphopoietin and endothelin axes was found in prurigo nodularis lesions, especially in the epidermis, indicating the importance of keratinocytes in prurigo nodularis pathogenesis.