Strong aggregation-induced electrochemiluminescence of pyrene-coordination metal-organic frameworks coupled with zero-valent iron as novel accelerator for ultrasensitive immunoassay.

Polycyclic aromatic hydrocarbons (PAHs) are excellent alternative luminophores for electrochemiluminescence (ECL) immunoassays. However, they are inevitably limited by the aggregation-caused quenching effect. In this study, aimed at eliminating the aggregation quenching of PAHs, luminescent metal-organic frameworks (MOFs) with 1,3,6,8-tetra(4-carboxybenzene)pyrene (H4TBAPy) as the ligand were exploited as a novel nano-emitter for the construction of ECL immunoassays. The luminophore exhibits efficient aggregation-induced emission enhancement, good acid-base resistance property and unusual ECL reactivity. In addition, the simultaneous use of potassium persulfate and hydrogen peroxide as dual co-reactants resulted in a synergistic enhancement of the cathodic ECL efficiency. The use of magnetic iron-nickel alloys as the multifunctional sensing platform can further enhance the ECL activity, and its enriched zero-valent iron as a co-reactant accelerator effectively drives ECL analytical performance. Profiting from the excellent characteristics, signal-on ECL immunoassays have been constructed. With carcinoembryonic antigen as the model analysis target, a detection limit of 0.63 pg/mL was obtained within the linear range of 1 pg/mL to 50 ng/mL, accompanied by excellent analytical performance. This report opens a new window for the rational design of efficient ECL illuminators, and the proposed ECL immunoassays may find promising applications in the detection of disease markers.

FeNi-MIL-88B-based electrochemiluminescence immunosensor for ultra-sensitive detection of CD44 protein via dual-quenching strategy.

BACKGROUND: Cluster of Differentiation 44 (CD44) is considered an important biomarker for various cancers, and achieving highly sensitive detection of CD44 is crucial, which plays a significant role in tumor invasion and metastasis, providing essential information for clinical tumor diagnosis. Commonly used methods for analysis include fluorescence spectroscopy (FL), photoelectrochemical analysis (PEC), electrochemical analysis (EC), and commercial ELISA kits. Although these methods offer high sensitivity, they can be relatively complex to perform experimentally. Electrochemiluminescence (ECL) has gained widespread research attention due to its high sensitivity, ease of operation, effective spatiotemporal control, and close to zero background signal. RESULTS: In this work, a sandwich-type ECL immunosensor for detecting CD44 was constructed using luminol as a luminophore. In this sensing platform, bimetallic MOFs (Pd@FeNi-MIL-88B) loaded with palladium nanoparticles (Pd NPs) were used as a novel enzyme mimic, exhibiting excellent catalytic performance towards the electroreduction of H2O2. The hybrids provided a strong support platform for luminol and antibodies, significantly enhancing the initial ECL signal of luminol. Subsequently, core-shell Au@MnO2 nanocomposites were synthesised by gold nanoparticles (Au NPs) encapsulated in manganese dioxide (MnO2) thin layers, as labels. In the luminol/H2O2 system, Au@MnO2 exhibited strong light absorption in the broad UV-vis spectrum, similar to the black body effect, and the scavenging effect of Mn2+ on O2•-, which achieved the dual-quenching of ECL signal. Under the optimal experimental conditions, the immunosensor demonstrated a detection range of 0.1 pg mL-1 - 100 ng mL-1, with a detection limit of 0.069 pg mL-1. SIGNIFICANCE: Based on Pd@FeNi-MIL-88B nanoenzymes and Au@MnO2 nanocomposites, a dual-quenching sandwich-type ECL immunosensor for the detection of CD44 was constructed. The proposed immunosensor exhibited excellent reproducibility, stability, selectivity, and sensitivity, and provided a valuable analytical strategy and technical platform for the accurate detection of disease biomarkers, and opened up potential application prospects for early clinical treatment.

Self-Assembly-Induced Enhancement of Cathodic Electrochemiluminescence of Copper Nanoclusters for a Split-Type Matrix Metalloproteinase 14 Sensing Platform.

The unique optoelectronic and tunable luminescent characteristics of copper nanoclusters (Cu NCs) make them extremely promising as luminophores. However, the limited luminescence intensity and stability of Cu NCs have restricted their application in the field of electrochemiluminescence (ECL). Herein, a self-assembly-induced enhancement strategy was successfully employed to enhance the cathodic ECL performance of flexible ligand-stabilized Cu NCs. Specifically, Cu NCs form ordered sheetlike structures through intermolecular force. The restriction of ligand torsion in this self-assembled structure leads to a significant improvement in the ECL properties of the Cu NCs. Experimental results demonstrate that the assembled nanoscale Cu NC sheets exhibit an approximately three-fold increase in cathodic ECL emission compared to the dispersed state of Cu NCs. Furthermore, assembled nanoscale Cu NCs sheets were utilized as signal probes in conjunction with a specific short peptide derived from the catalytic structural domain of matrix metalloproteinase 14 (MMP 14) as the identification probe, thereby establishing a split-type ECL sensing platform for the quantification of NMP 14. The investigation has revealed the exceptional performance of assembled nanoscale Cu NCs sheets in ECL analysis, thus positioning them as novel and promising signal probes with significant potential in the field of sensing.

A Co-Reactive Immunosensor Based on Ti3C2Tx MXene@TiO2-MoS2 Hybrids Promoting luminol@Au@Ni-Co NCs Electrochemiluminescence for CYFRA 21-1 Detection.

The construction of assays is capable of accurately detecting cytokeratin-19 (CYFRA 21-1), which is critical for the rapid diagnosis of nonsmall cell lung cancer. In this work, a novel electrochemiluminescence (ECL) immunosensor based on the co-reaction promotion of luminol@Au@Ni-Co nanocages (NCs) as ECL probe by Ti3C2Tx MXene@TiO2-MoS2 hybrids as co-reaction accelerator was proposed to detect CYFRA 21-1. Ni-Co NCs, as a derivative of Prussian blue analogs, can be loaded with large quantities of Au NPs, luminol, and CYFRA 21-1 secondary antibodies due to their high specific surface area. To further improve the sensitivity of the developed ECL immunosensor, Ti3C2Tx MXene@TiO2-MoS2 hybrids were prepared by in situ growth of TiO2 nanosheets on highly conductive Ti3C2Tx MXene, and MoS2 was homogeneously grown on Ti3C2Tx MXene@TiO2 surfaces by the hydrothermal method. Ti3C2Tx MXene@TiO2-MoS2 hybrids possess excellent catalytic performance on the electro-redox of H2O2 generating more O2·- and obtaining optimal ECL intensity of the luminol/H2O2 system. Under the appropriate experimental conditions, the quantitative detection range of CYFRA 21-1 was from 0.1 pg mL-1 to 100 ng mL-1, and the limit of detection (LOD) was 0.046 pg mL-1. The present sensor has a lower LOD with a wider linear range, which provides a new analytical assay for the early diagnosis of small-cell-type lung cancer labels.

Ultrasensitive Detection of SARS-CoV-2 Nucleocapsid Protein Based on Porphyrin-Based Metal-Organic Gels with Highly Efficient Electrochemiluminescence at Low Potential.

Metal-organic gels (MOGs) are a new type of intelligent soft material, which are bridged by metal ions and organic ligands through noncovalent interactions. In this paper, we prepared highly stable P-MOGs, using the classical organic electrochemiluminescence (ECL) luminescence meso-tetra(4-carboxyphenyl)porphine as the organic ligand and Fe3+ as the metal ion. Surprisingly, P-MOGs can stably output ECL signals at a low potential. We introduced P-MOGs into the ECL resonance energy transfer strategy (ECL-RET) and constructed a quenched ECL immunosensor for the detection of the SARS-CoV-2 nucleocapsid protein (SARS-CoV-2-N). In the ECL-RET system, P-MOGs were used as energy donors, and Au@Cu2O@Fe3O4 were selected as energy acceptors. The ultraviolet-visible spectrum of Au@Cu2O@Fe3O4 partially overlaps with the ECL spectrum of P-MOGs, which can effectively touch off the ECL-RET behavior between the donors and receptors. Under the ideal experimental situation, the linear detection range of the SARS-CoV-2-N concentration was 10 fg/mL to 100 ng/mL, and the limit of detection was 1.5 fg/mL. This work has broad application prospects for porphyrin-MOGs in ECL sensing.

Development of reusable electrochemiluminescence sensing microchip for detection of vomitoxin.

In this work, a reusable DNA sensing microchip was developed for detection of vomitoxin (deoxynivalenol, DON) in sorghum using Cd-based core-shell CdSe@CdS quantum dots (QDs) as promising electrochemiluminescence (ECL) emitter. The size-adjustable aqueous phase CdSe@CdS QDs were prepared through homogeneous method, exhibiting strong cathodic ECL emission with a central wavelength of 520 nm in S2O82- coreactant. And gold nanoparticles-modified iron cobalt cyanide hydrate (Fe-Co-Au) was introduced as an accelerator to amplify the ECL signal. ECL signal was quenched after the formation of a double-stranded (dsDNA) S1-S2 by generating an electron transfer system between the emitter and ferrocene (Fc), which are modified on the aptamer (ssDNA S1) and its complement sequence (ssDNA S2), respectively. When the target DON is presence, the aptamer ssDNA S1 will bind to the DON and trigger the unbinding of double strands DNA and the release of the ssDNA S2, thus the signal can be generated. This approach offers a feasible method for the detection of DON within the range of 1 ng/mL to 200 ng/mL.

Ultrasensitive Electrochemiluminescence Biosensor Based on Efficient Signal Amplification of Copper Nanoclusters Induced by CaMnO3 for CD44 Trace Detection.

Metal nanoclusters (Me NCs) have become a research hotspot in the field of electrochemiluminescence (ECL) sensing analysis. This is primarily attributed to their excellent luminescent properties and biocompatibility along with their easy synthesis and labeling characteristics. At present, the application of Me NCs in ECL mainly focuses on precious metals, whose high cost, to some extent, limits their widespread application. In this work, Cu NCs with cathode ECL emissions in persulfate (S2O82-) were prepared as signal probes using glutathione as ligands, which exhibited stable luminescence signals and high ECL efficiency. At the same time, CaMnO3 was introduced as a co-reaction promoter to increase the ECL responses of Cu NCs, thereby further expanding their application potential in biochemical analysis. Specifically, the reversible conversion of Mn3+/Mn4+ greatly promoted the generation of sulfate radicals (SO4•-), providing a guarantee for improving the luminescence signals of Cu NCs. Furthermore, a short peptide (NARKFYKGC) was introduced to enable the fixation of antibodies to specific targets, preventing the occupancy of antigen-binding sites (Fab fragments). Therefore, the sensitivity of the biosensor could be significantly enhanced by releasing additional Fab fragments. Considering the approaches discussed above, the constructed biosensor could achieve sensitive detection of CD44 over a broad range (10 fg/mL-100 ng/mL), with an ultralow detection limit of 3.55 fg/mL (S/N = 3), which had valuable implications for the application of nonprecious Me NCs in biosensing analysis.

Magnetic photoelectrochemical sensor array utilizing addressing sensing strategy for simultaneous detection of amyloid-ß 42 and microtubule-associated protein tau.

The accurate diagnosis of diseases can be improved by detecting multiple biomarkers simultaneously. This study presents the development of a magnetic photoelectrochemical (PEC) immunosensor array for the simultaneous detection of amyloid-ß 42 (Aß) and microtubule-associated protein (Tau), which are markers for neurodegenerative disorders. A metal-organic framework (MOF) derivative, Fe2O3@FeS2 magnetic composites with exceptional photoelectric and ferromagnetic properties was synthesized while preserving the original structure and advantages. Thus, the immunoassembly process of the sensor can be carried out in homogeneous solution and recovered by magnetic separation. For simultaneous detection, a chip is divided into multiple independent sensing sites, which have the same preparation and detection environment, allowing for the implementation of a self-calibration method. The sensor array demonstrates considerable detection ranges of 0.01-100 ng mL-1 for Aß and 0.05-100 ng mL-1 for Tau, with low detection limits of 2.1 pg mL-1 for Aß and 7.9 pg mL-1 for Tau. The PEC sensor array proposed in this study exhibits exceptional stability, selectivity, and reproducibility, providing a new method for detecting multiple markers.

Multimetal-Based Metal-Organic Framework System for the Sensitive Detection of Heart-Type Fatty Acid Binding Protein in Electrochemiluminescence Immunoassay.

In this work, an electrochemiluminescence (ECL) quenching system using multimetal-organic frameworks (MMOFs) was proposed for the sensitive and specific detection of heart-type fatty acid-binding protein (H-FABP), a marker of acute myocardial infarction (AMI). Bimetallic MOFs containing Ru and Mn as metal centers were synthesized via a one-step hydrothermal method, yielding RuMn MOFs as the ECL emitter. The RuMn MOFs not only possessed the strong ECL performance of Ru(bpy)32+ but also maintained high porosity and original metal active sites characteristic of MOFs. Moreover, under the synergistic effect of MOFs and Ru(bpy)32+, RuMn MOFs have more efficient and stable ECL emission. The trimetal-based MOF (FePtRh MOF) was used as the ECL quencher because of the electron transfer between FePtRh MOFs and RuMn MOFs. In addition, active intramolecular electron transfer from Pt to Fe or Rh atoms also occurred in FePtRh MOFs, which could promote intermolecular electron transfer and improve electron transfer efficiency to enhance the quenching efficiency. The proposed ECL immunosensor demonstrated a wide dynamic range and a low detection limit of 0.01-100 ng mL-1 and 6.8 pg mL-1, respectively, under optimal conditions. The ECL quenching system also presented good specificity, stability, and reproducibility. Therefore, an alternative method for H-FABP detection in clinical diagnosis was provided by this study, highlighting the potential of MMOFs in advancing ECL technology.

Ternary electrochemiluminescence quenching effects of CuFe2O4@PDA-MB towards self-enhanced Ru(dcbpy)32+ functionalized 2D metal-organic layer and application in carcinoembryonic antigen immunosensing.

BACKGROUND: Carcinoembryonic antigen (CEA) is a significant glycosylated protein, and the unusual expression of CEA in human serum is used as a tumor marker in the clinical diagnosis of many cancers. Although scientists have reported many ways to detect CEA in recent years, such as electrochemistry, photoelectrochemistry, and fluorescence, their operation is complex and sensitivity is average. Therefore, finding a convenient method to accurately detect CEA is significance for the prevention of malignant tumors. With high sensitivity, quick reaction, and low background, electrochemiluminescence (ECL) has emerged as an essential method for the detection of tumor markers in blood. RESULTS: In this work, a "signal on-off" ECL immunosensor for sensitive analysis of CEA ground on the ternary extinction effects of CuFe2O4@PDA-MB towards a self-enhanced Ru(dcbpy)32+ functionalized metal-organic layer [(Hf)MOL-Ru-PEI-Pd] was prepared. The high ECL efficiency of (Hf)MOL-Ru-PEI-Pd originated from the dual intramolecular self-catalysis, including intramolecular co-reaction between polyethylenimine (PEI) and Ru(dcbpy)32+. At the same time, loading Pd NPs onto (Hf)MOL-Ru-PEI could not only improve the electron transfer ability of (Hf)MOL-Ru-PEI, but also provide more active sites for the reaction of Ru(dcbpy)32+ and PEI. In the presence of CEA, CuFe2O4@PDA-MB-Ab2 efficiently quenches the excited states of (Hf)MOL-Ru-PEI-Pd by PDA, Cu2+, and methylene blue (MB) via energy and electron transfer, leading to an ECL signal decrease. Under optimal conditions, the proposed CEA sensing strategy showed satisfactory properties ranging from 0.1 pg mL-1 to 100 ng mL-1 with a detection limit of 20 fg mL-1. SIGNIFICANCE: The (Hf)MOL-Ru-PEI-Pd and CuFe2O4@PDA-MB were prepared in this work might open up innovative directions to synthesize luminescence-functionalized MOLs and effective quencher. Besides, the ECL quenching mechanism of Ru(dcbpy)32+ by MB was successfully explained by the inner filter effect (ECL-IFE). At last, the proposed immunosensor exhibits excellent repeatability, stability, and selectivity, and may provide an attractive way for CEA and other disease markers determination.

Double-Amplified Electrochemiluminescence Immunoassay Sensor for Highly Sensitive Detection of CA19-9 Using a Ternary Semiconductor CdSSe.

In this paper, an electrochemiluminescence (ECL) immunosensor for ultrasensitive detection of CA19-9 was constructed using ternary compound CdSSe nanoparticles as ECL emitter. The immunosensor employs Cu2S and gold-doped diindium trioxide (Au-In2O3) nanocubes as coreaction accelerators to achieve a double-amplification strategy. In general, a hexagonal maple leaf-shaped Cu2S with a large surface area was selected as the template, and the in situ growth of CdSSe on its surface was achieved using a hydrothermal method. The presence of Cu2S not only inhibited the aggregation of CdSSe nanoparticles to reduce their surface energy but also acted as an ECL cathode coreaction promoter, facilitating the generation of SO4•-. Consequently, the ECL intensity of CdSSe was significantly enhanced, and the reduction potential was significantly lower. In addition, the template method was employed to synthesize Au-In2O3 nanocubes, which offers the advantage of directly connecting materials with antibodies, resulting in a more stable construction of the immunosensor. Furthermore, In2O3 serves as a coreaction promoter, enabling the amplification strategy for ECL intensity of CdSSe, thus contributing to the enhanced sensitivity and performance of the immunosensor. The constructed immunosensor exhibited a wide linear range (100 µU mL-1 to 100 U mL-1) and a low detection limit of 80 µU mL-1, demonstrating its high potential and practical value for sensitive detection of CA19-9.

Bandgap-Regulated Electrochemiluminescence Enhancement Strategy for Florfenicol Detection Based on ZrCuO3: A Multimodal Luminophore.

The low electrochemiluminescence (ECL) efficiency issue of zirconia (ZrO2) has been a pressing problem since its discovery. In this study, a bandgap-regulated ECL enhancement strategy was developed to improve the ECL efficiency of ZrO2. Specifically, through the calcination of metal-organic frameworks (MOFs), the MOF-derived bimetallic oxide ZrCuO3 was synthesized. Compared to ZrO2, the synthesized ZrCuO3 exhibited a narrower bandgap and higher electron transfer efficiency, leading to enhanced ECL efficiency. Further investigation of the ECL emitter revealed that ZrCuO3 exhibited multimodal ECL emission: annihilation ECL and co-reactant participation ECL (including anodic ECL with tripropylamine as a co-reactant and cathodic ECL with K2S2O8 as a co-reactant). The anodic ECL with the highest efficiency was selected as the main mode for detecting the target in the aptasensor. Annihilation ECL and cathodic ECL served as alternative modes to ensure stability and continuity of the sensing system. Based on the bandgap-regulated strategy of ZrCuO3, a sensing chip with ITO as the working electrode was designed for the sensitive detection of florfenicol (FF). The constructed signal "off-on-off" aptasensor exhibited excellent detection performance for FF in the range of 0.0005-200 ng/mL. The proposed method provided a novel strategy for the analysis of other antibiotics or biomolecules.

Photoelectrochemical Sensor with a Z-Scheme Fe2O3/CdS Heterostructure for Sensitive Detection of Mercury Ions.

Mercury (Hg2+) is a highly toxic element and can seriously affect human health. This work proposed a photoelectrochemical (PEC) sensor with a Z-scheme Fe2O3/CdS heterostructure and two thymine-rich DNA strands (DNA-1 and Au@DNA-2) for sensitive detection of Hg2+. The light excitation of the Fe2O3/CdS composite accelerated the electron transfer among Fe2O3, CdS, and the electrode to produce a stable photocurrent response. Upon the recognition of Hg2+ to thymine bases (T) in two DNA strands to form a stable T-Hg2+-T biomimetic structure, the photocurrent response increased with the increasing concentration of Hg2+ due to the opening of electronic transmission channels from Au nanoparticles to Fe2O3/CdS nanocomposite. Under the optimal conditions screened by the Box-Behnken experiments, the proposed PEC sensor showed excellent analytical performance for Hg2+ detection with high sensitivity, a detection limit of 0.20 pM at a signal-to-noise ratio of 3, high selectivity, a detectable concentration range of 1 pM-100 nM, and acceptable stability. The good recovery and low relative standard deviation for the analysis of Hg2+ in lake and tap water samples demonstrated the potential application of the designed Z-scheme Fe2O3/CdS heterostructure in the PEC detection of heavy metal ions.

Magnetically Controlled and Addressable Photoelectrochemical Sensor Array with Self-Calibration for the Label-Free Detection of Amyloid ß-Proteins.

A label-free addressable photoelectric immunosensor array was designed for the detection of amyloid ß-proteins based on magnetic separation and self-calibration strategies. In this paper, Na2Ti6O13 with a flower-like morphology was prepared by the hydrothermal method; after continuously combining Fe3O4 and CdS, it was endowed with magnetism and better photoelectric activity. Subsequently, a series of reactions occurred in the solution, and the magnetic separation method was used to enrich the target. On the other hand, the ITO glass was separated into eight sites (2 × 4) using magnets, and a light shield was utilized to prevent light exposure, resulting in addressable and continuous detection. After the uniform preparation of magnetic photoelectric materials and precise control of testing conditions, the relative errors among different sites have been effectively reduced. Moreover, incorporating a self-calibration strategy has allowed the sensor array to achieve greater accuracy. The proposed photoelectrochemical biosensor exhibits a good relationship with amyloid ß-protein ranging from 0.01 to 100 ng mL-1 with a limit of detection of 1.1 pg mL-1 and exhibits excellent specificity, reproducibility, and stability.

Antioxidant Cascade Modulated Electrochemiluminescence by a Biomimetic Metal-Organic Framework with Dual Enzymatic Activity for Disease Marker Immunoassays.

High-performance electrochemiluminescence is a significant approach for the examination of disease biomarkers, and the utilization of innovative electrochemiluminescence detection systems represents a viable strategy to enhance the efficacy of ECL analysis. In this work, the biomimetic engineering metal-organic framework (MOF-818) has realized the ultrasensitive ECL immunoassay of disease markers based on the guidance of the free radical scavenging strategy provided by the antioxidant cascade. Initially, we synthesized a hydrogen-bonded organic framework (HOF) consisting of luminol and three active ligands based on simple room-temperature self-assembly. The luminol-HOF (L-HOF) showed more stable and brighter ECL luminescence activity than the monomer due to the nano-confinement enhancement of the coordinated luminol units. Subsequently, MOF-818 with biomimetic superoxide dismutase (SOD) and catalase (CAT) activities were recruited for the first time as quenching agents for sandwich immunoassay mode. The enzyme activity leads to the reverse transformation of superoxide anion radicals (O2-) and further antioxidant decomposition, decreasing in the responsiveness of luminol ECL signals. Using carcinoembryonic antigen (CEA) as an analytical model, a detection limit of 0.457 pg/mL was obtained within a detection range of 0.001-50 ng/mL. We believe that this novel sandwich sensing model based on enzyme activity provides a meaningful potential tool for precise detection, expanding the broader application of nanoenzymes in analysis.

Synergetic-effect-enhanced electrochemiluminescence of zein-protected Au-Ag bimetallic nanoclusters for CA15-3 detection.

In this work, a sandwich-type electrochemiluminescence (ECL) system was constructed for the detection of CA15-3. Gold-silver bimetallic nanoclusters (Au-Ag BNCs) with zein as a protective ligand were synthesized, and the excellent ECL performance of this material was demonstrated for the first time. Zein carrying a variety of groups that ligated with Au-Ag BNCs, forming a protective shell of zein, effectively prevented clusters from aggregating or growing into larger nanoparticles. The synergistic effect of the bimetal promotes the ECL emission, making this nanoscale material an ideal ECL probe. GO-PANI, which effectively promoting the production of sulfate radicals of the co-reactant and significantly increasing the ECL strength, was a good sensing platform for antibody immobilization. Consequently, we constructed an ECL sensor with GO-PANI as the sensing platform and Au-Ag BNCs@zein as the ECL probe, with a detection range of 0.001-100 U mL-1 and a detection limit of 0.0003 U mL-1, provided a strong support for the sensor for future CA15-3 detection applications.

Dual-Signal Integrated Aptasensor for Microcystin-LR Detection via In Situ Generation of Silver Nanoclusters Induced by Circular DNA Strand Displacement Reactions.

Inspired by the signal accumulation of circular DNA strand displacement reactions (CD-SDRs) and the in situ generation of silver nanoclusters (AgNCs) from signature template sequences, a dual-signal integrated aptasensor was designed for microcystin-LR (MC-LR) detection. The aptamer was programmed to be included in an enzyme-free CD-SDR, which utilized MC-LR as the primer and outputted the H1/H2 dsDNA in a continuous manner according to the ideal state. Ingeniously, H1/H2 dsDNA was enriched with signature template sequences, allowing in situ generation of AgNCs signal probes. To enhance the signal amplification performance, co-reaction acceleration strategies and CRISPR-Cas12a nucleases were invoked. The H1/H2 dsDNA could trigger the incidental cleavage performance of CRISPR-Cas12a nucleases: cis-cleavage reduced signature template sequences for the synthetic AgNCs, while trans-cleavage enabled fluorescence (FL) analysis. Meanwhile, AuPtAg was selected as the substrate material to facilitate the S2O82- reduction reaction for enhancing the electrochemiluminescence (ECL) basal signals. ECL and FL detection do not interfere with each other and have improved accuracy and sensitivity, with limits of detection of 0.011 and 0.023 pmol/L, respectively. This widens the path for designing dual-mode sensing strategies for signal amplification.

Long noncoding RNA XLOC_006786 inhibits the proliferation, invasion and metastasis of osteosarcoma cells through NOTCH3 signaling pathway by targeting miR-491-5p.

Recent research has indicated that Long noncoding RNAs (LncRNAs) are crucial in many disorders, especially tumors. However, the exact role of LncRNA XLOC_006786 (LncRNA-SPIDR-2:1) in malignancies, especially in human osteosarcoma, is unclear. The results of RT‒qPCR, western blotting, CCK-8 assays, and Transwell assays showed that LncRNA XLOC_006786 inhibited osteosarcoma cell proliferation, invasion, and migration, indicating that it may be a tumor suppressor gene in osteosarcoma. We found that LncRNA XLOC_006786 negatively regulated NOTCH3, which is an oncogenic gene in osteosarcoma, as we previously reported. Bioinformatics analysis showed that miR-491-5p may be a direct target of LncRNA XLOC_006786, while NOTCH3 is a key target of miR-491-5p. Then, we verified that LncRNA XLOC_006786 could prevent lung metastatic osteosarcoma in vivo. Taken together, our research showed that LncRNA XLOC_006786 suppresses osteosarcoma proliferation, invasion, and metastasis through the NOTCH3 signaling pathway by targeting miR-491-5p.

DNA Tile and Invading Stacking Primer-Assisted CRISPR-Cas12a Multiple Amplification System for Entropy-Driven Electrochemical Detection of MicroRNA with Tunable Sensitivity.

Conventional electrochemical detection of microRNA (miRNA) encounters issues of poor sensitivity and fixed dynamic range. Here, we report a DNA tile and invading stacking primer-assisted CRISPR-Cas12a multiple amplification strategy to construct an entropy-controlled electrochemical biosensor for the detection of miRNA with tunable sensitivity and dynamic range. To amplify the signal, a cascade amplification of the CRISPR-Cas12a system along with invading stacking primer signal amplification (ISPSA) was designed to detect trace amounts of miRNA-31 (miR-31). The target miR-31 could activate ISPSA and produce numerous DNAs, triggering the cleavage of the single-stranded linker probe (LP) that connects a methylene blue-labeled DNA tile with a DNA tetrahedron to form a Y-shaped DNA scaffold on the electrode. Based on the decrease of current, miR-31 can be accurately and efficiently detected. Impressively, by changing the loop length of the LP, it is possible to finely tune the entropic contribution while keeping the enthalpic contribution constant. This strategy has shown a tunable limit of detection for miRNA from 0.31 fM to 0.56 pM, as well as a dynamic range from ∼2200-fold to ∼270,000-fold. Moreover, it demonstrated satisfactory results in identifying cancer cells with a high expression of miR-31. Our strategy broadens the application of conventional electrochemical biosensing and provides a tunable strategy for detecting miRNAs at varying concentrations.

Hierarchically Structured and Highly Dispersible MOF Nanozymes Combining Self-Assembly and Biomineralization for Sensitive and Persistent Chemiluminescence Immunoassay.

Metal-organic frameworks (MOF) are promising candidates for the construction of artificial nanozymes and have found applications in many fields. However, the preparation of nanosized MOF materials with high performance and good dispersibility is still a big challenge and is in great demand as signal labels for immunoassays. In this work, hierarchically structured and highly dispersible MOF nanoparticles were facilely prepared in a one-pot method. Self-assembled micelles from PEGylated hematin were used as structured templates to mediate the formation of zeolitic imidazole framework-8 (ZIF-8) nanoparticles in aqueous solution. The encapsulation of micelles in ZIF-8 frameworks produces well-dispersed nanoparticles and generates dual-confinement effects for catalytic hematin. Owing to the hierarchical structures, the formed MOF nanozymes show enhanced peroxidase-like activity and enable persistent chemiluminescence behaviors for the luminol system. Sandwich-type chemiluminescence immunoassays for carcinoembryonic antigen (CEA) were proposed using MOF nanozymes as signal labels, and good analytical performances were achieved. The combination of self-assembly and biomineralization may open new avenues for the development of MOF nanomaterials.