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Full utilization of the excited species at both singlet states (1R*) and triplet states (3R*) is crucial to improving electrochemiluminescence (ECL) efficiency but is challenging for organic luminescent materials. Here, an aggregation‐induced delayed ECL (AIDECL) active organic dot (OD) containing a benzophenone acceptor and dimethylacridine donor is reported, which shows high ECL efficiency via reverse intersystem crossing (RISC) of non‐emissive 3R* to emissive 1R*, overcoming the spin‐forbidden radiative decay from 3R*. By introducing dual donor‐acceptor pairs into luminophores, it is found that nonradiative pathway could be further suppressed via enhanced intermolecular weak interactions, and multiple spin‐up conversion channels could be activated. As a consequence, the obtained OD enjoys a 6.8‐fold higher ECL efficiency relative to the control AIDECL‐active OD. Single‐crystal studies and theoretical calculations reveal that the enhanced AIDECL behaviors come from the acceleration of both radiative transition and RISC. This work represents a major step towards purely organic, high‐efficiency ECL dyes and a direction for the design of next‐generation ECL dyes at the molecular level. [ABSTRACT FROM AUTHOR]

For the first time, we report novel aggregation-induced electrochemiluminescence (AIECL) of organic dots in aqueous media, with near-infrared II (NIR-II) luminescence peaked at 906 nm. Furthermore, a hybrid mechanism of ECL generation is revealed by various experiments in conjunction with theoretical calculations. This work opens a window for exploring efficient organic dye-based NIR-II AIECL emitters. [ABSTRACT FROM AUTHOR]

Classic tris(bipyridine)ruthenium(II) complex (Ru-bpy) with high electrochemiluminescence (ECL) efficiency still suffers from a serious aggregation-caused quenching (ACQ) problem, which greatly weakens its ECL efficiency to restrict further applications in solid-state ECL imaging and light-emitting devices. Herein, the crystallization-induced enhanced ECL (CIE-ECL) of tris(bipyridine) ruthenium(II) derivatives (Ru-TPE) are reported by decorating Ru-bpy with inherent aggregation-induced emission active tetraphenylethene (TPE), which effectively eliminates the detrimental π-π stacking interactions and thus helps Ru-bpy surmount notorious ACQ effect in the aqueous phase. The Ru-TPE shows negligible ECL emission in solution but produces a strong ECL emission upon crystallization. Surprisingly, the ECL efficiency of Ru-TPE crystals is 20 and 3 times higher than that of its solution and Ru-bpy crystals, respectively. Experimental and structural analysis reveals that such a CIE-ECL effect originates from the restricted intramolecular rotation and ordered molecular packing. Moreover, the high-resolution ECL imaging of a single Ru-TPE crystal is successfully demonstrated. This work provides a new design strategy for achieving high efficiency in solid-state ECL imaging and devices. [ABSTRACT FROM AUTHOR]

A novel electrochemiluminescence (ECL) Janus emitter realizes dual‐mode biosensing for multiple disease‐related biomarkers from cells. Each Janus emitter consists of ruthenium (II) complex and luminol polymer doped hemispheres that are spatially separated but function simultaneously, generating intense dual‐ECL emissions. This design effectively eliminates optical and electrochemical interferences between different ECL mono‐luminophores in comparison with the homogenous nanostructures, thereby improving ECL efficiency and detection sensitivity. Accordingly, the ECL Janus emitters provide a proof of concept for the construction of the ratiometric ECL sensing of H2O2. Furthermore, this Janus emitter enables simultaneous identification and quantification of the intracellular cancer‐related dual microRNAs. This work not only inspires the development of ECL Janus emitters, but also highlights their potential in bioanalysis and clinical diagnosis in the future. [ABSTRACT FROM AUTHOR]

We report a photodynamic therapy driven by electrochemiluminescence (ECL). The luminescence generated by Ru(bpy)32+ and co‐reactant tripropylamine (TPA) pair acts as both optical readout for ECL imaging, and light source for the excitation of photosensitizer to produce reactive oxygen species (ROS) in photodynamic therapy (PDT) system. The ECL‐driven PDT (ECL‐PDT) relies on the effective energy transfer from ECL emission to photosensitizer chlorin e6 (Ce6), which sensitizes the surrounding O2 into ROS. The dynamic process of gradual morphological changes, the variation of cell‐matrix adhesions, as well as the increase of cell membrane permeability in the process of ECL‐PDT were monitored under ECL microscopy (ECLM) with good spatiotemporal resolution. Combining real‐time imaging with ECL‐PDT, this new strategy provides not only new insights into dynamic cellular processes, but also promising potential of ECL in clinical applications. [ABSTRACT FROM AUTHOR]

The inside walls of a nanopipette tip are decorated by a Pt deposit that is used as an open bipolar electrochemiluminescence (ECL) device to achieve intracellular wireless electroanalysis. The synergetic actions of nanopipette and of bipolar ECL lead to the spatial confinement of the voltage drop at the level of the Pt deposit, which generates ECL emission from luminol. The porous structure of Pt deposit permits the electrochemical transport of intracellular molecules into the nanopipette that is coupled with enzymatic reactions. Thus, the intracellular concentrations of hydrogen peroxide or glucose are measured in vivo as well as the intracellular sphingomyelinase activity. In comparison with the classic bipolar ECL, the remarkably low potential applied in our approach is restricted inside the nanopipette and it minimizes the potential bias of the voltage on the cellular activity. Accordingly, this wireless ECL approach provides a new direction for analysis of single living cells. [ABSTRACT FROM AUTHOR]

We developed an electrochemiluminescence (ECL) microscopy technique to image the structure-dependent electrocatalytic reactivity of bimetallic Pd–Au nanorods (NRs) at the single-particle level. [ABSTRACT FROM AUTHOR]

Abstract: Noble metal nanoparticles are promising catalysts in electrochemical reactions, while understanding the relationship between the structure and reactivity of the particles is important to achieve higher efficiency of electrocatalysis, and promote the development of single‐molecule electrochemistry. Electrogenerated chemiluminescence (ECL) was employed to image the catalytic oxidation of luminophore at single Au, Pt, and Au‐Pt Janus nanoparticles. Compared to the monometal nanoparticles, the Janus particle structure exhibited enhanced ECL intensity and stability, indicating better catalytic efficiency. On the basis of the experimental results and digital simulation, it was concluded that a concentration difference arose at the asymmetric bimetallic interface according to different heterogeneous electron‐transfer rate constants at Au and Pt. The fluid slip around the Janus particle enhanced local redox reactions and protected the particle surface from passivation. [ABSTRACT FROM AUTHOR]

Bipolar electrochemistry is based on the gradient distribution of free-electron density along an electrically isolated electrode, which causes a positive electrode potential at one end and a negative potential at the other, allowing for wide applications in analytical chemistry and materials science. To take full advantage of its wireless and high-throughput features, various types of optical probes, such as pH indicators and fluorescence and electrochemiluminescence reagents, have often been used to indirectly monitor the interfacial electron transfer through chromogenic or fluorogenic reactions. Herein, we report the first probe-free imaging approach that can directly visualize the distribution of the interfacial potential in bipolar electrodes, providing essential information for the validation and development of the theory and applications of bipolar electrochemistry. This approach is based on the sensitive dependence of surface plasmon resonance imaging on the local electron density in the electrode, which enables the direct mapping of potential with a spatial resolution close to the optical diffraction limit, a temporal resolution of 50 ms, and a sensitivity of 10 mV. In addition, in contrast to previous optical readouts that relied on faradaic reactions, the present work achieved the impedance-based measurements under non-faradaic conditions. It is anticipated that this technique will greatly expand the application of bipolar electrochemistry as a platform for chemical and biosensing. [ABSTRACT FROM AUTHOR]

Gold nanoparticle dimers assembled on the surface of CdS QD thin films served as nano-antennas to mediate the distance-dependent plasmon enhanced electrochemiluminescence of QDs. [ABSTRACT FROM AUTHOR]

An advanced biosensor based on a closed bipolar electrode (BPE)-electrochemiluminescence (ECL) strategy is proposed for cancer cell adhesion, specific recognition, and detection with dual biomarkers. The system consists of a two-channel polydimethylsiloxane (PDMS) chip (sensing channel and reporting channel) connected through a U-shaped indium tin oxide BPE at a glass surface. A sandwich-type cancer cell detection model is developed at the cathode of the BPE with two recognition molecules, folic acid (FA) and an aptamer. On the basis of the high affinity between FA and the folate receptor that is overexpressed at a cancer cell membrane as well as the excellent conductivity of graphene-Au conjugates, this strategy could achieve the sensitive detection of HL-60 cells, with a limit as low as 18 cells in 30 μL of cell suspension. Control experiments confirm that the sandwich assay specifically captures cancer cells and recognizes target cells. [ABSTRACT FROM AUTHOR]

A novel electrochemiluminescence resonance energy transfer (ECL-RET) system from Eu 3 + -doped CdS nanocrystals (CdS:Eu NCs) to Ru(bpy) 3 2 + -doped silica nanoparticle (RuSi) was designed for ultrasensitive detection of prostate-specific antigen (PSA). The platform consists of a CdS:Eu NCs film on glassy carbon electrode (GCE) as ECL emitter and a sandwich-type immunocomplex formed by the primary antibody, PSA and RuSi-tagged second antibody. This system showed a maximum of 4.83-fold enhancement of ECL intensity at 620 nm due to the efficient ECL-RET and high Ru(bpy) 3 2 + quantum yields. By the signal amplification of RuSi and the specific antibody–antigen interactions, this ECL-RET system could sensitively respond down to 1.0 fg mL − 1 PSA. [ABSTRACT FROM AUTHOR]

A mesoporous silica film-assisted amplification method is reported for the first time for the sensitive electrochemiluminescence detection of cancer cells. [ABSTRACT FROM AUTHOR]

Using the DNA bio-gate and duplex-specific nuclease assisted target recycling, a facile electrochemiluminescence assay was developed for the sensitive detection of survivin mRNA. [ABSTRACT FROM AUTHOR]

In this work, a simple and effective approach to obtain stable, nontoxic and strong electrochemiluminescence (ECL) interfaces is provided by coating TiO2 nanoparticles (NPs) modified glassy carbon electrode (GCE) surfaces with Nafion. Unlike a decrease of the current resulting from the blocked diffusion usually displayed in electrochemical processes by Nafion coating, a Nafion/TiO2 NPs modified electrode not only shows a highly stable ECL, but also shows an 8-fold increase of ECL intensity and a reduction of the overpotential of ca. 300 mV in the presence of K2S2O8 as co-reactant, compared with those of bare TiO2 NPs modified electrodes. The roles of Nafion coating on TiO2 NPs in the ECL process are proposed to be twofold: to provide refuge for the free radicals and to enhance the electron-hole recombination. Benefiting from its excellent ECL performance, the cationic exchange function of Nafion and the susceptible to being oxidized performance of dopamine (DA) by holes, the Nafion/TiO2 composite electrode could be used to sensitively and selectively detect DA with a detection limit of 1.0×10−11 M and a linear range of 1.0×10−11-6.0×10−7 M. The coexisting anionic species such as excess ascorbic acid show little interference on DA detection. [ABSTRACT FROM AUTHOR]

Based on the K-doped graphene–CdS:Eu NC composites and the nicking endonuclease (NEase) assisted strand-scission cycle, we have developed an ultrasensitive and selective electrochemiluminescence (ECL) DNA biosensor using the G-quadruplex–hemin-based DNAzyme which acts as an electrocatalyst for the reduction of H2O2, the coreactant of CdS:Eu NCs ECL. [ABSTRACT FROM AUTHOR]

A reusable potassium ion biosensor was reported for the first time based on the reversible DNA structural change and the interaction between surface plasmons of Au nanoparticles (NPs) and the ECL emission of CdS nanocrystals (NCs). [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD), a progressive neurological disorder, presents challenges in early detection due to the limitations and costs of neuropsychological tests and neuroimaging. This study introduces a visual electrochemiluminescence (ECL) sensing device employing red and green signal lights on dual-channel closed bipolar electrodes (BPEs) for simultaneous Aβ oligomers and Tau proteins detection. To mitigate cross-chemical reactions, we physically separated target detection and ECL production within different chambers connected by BPEs. Utilizing efficient gold clusters (Au NCs) and Ru(bpy) 3 2+ as green and red emitters, respectively, along with methylene blue (MB) as the recognition probe on the cathode sensing platform, we achieved a detection limit of 2.6 pM for Aβ oligomers and 0.3 pM for Tau proteins by measuring visual ECL intensity at two anodic poles of BPEs. This approach minimizes cross-chemical reactions, ensures robust ECL signal sensors, and allows integration of multiple sensors on a single chip. The proposed portable bipolar electrode chips employing ECL technology show promise for early and precise Alzheimer's disease diagnosis and personal healthcare. [Display omitted] ● An ECL imaging device based on dual-channel closed bipolar electrode was developed. ● The method minimized cross-chemical reactions, integrated multiple sensors in a chip. ● Highly efficient Au NCs and Ru(bpy) 3 2+ as green and red emitters, respectively. ● The simultaneous detection of Tau protein and Aβ oligomers was achieved. [ABSTRACT FROM AUTHOR]

[Display omitted] • The basic synthetic strategies of porous nanomaterials for ECL biosensing are summarized. • Recent developments of porous nanomaterials for ECL biosensing are presented. • The challenges and prospects of porous nanomaterials for ECL systems are concluded. Porous nanomaterials have attracted widely attention across several scientific communities due to their high porosity, large specific surface area, and versatile functionality. In electrochemiluminescence (ECL) realm, the pore-rich nanostructures can not only effectively load abundant guest ECL luminophores for signal amplification, but also promote the mass and charge transports between the bulk solution and the electrode surface. Some porous nanomaterials with metal centers even display inherent catalytic capacity to assist coreactant ECL. In this review, the basic synthesis strategies and emerging advanced applications of several porous nanomaterials for ECL biosensing are reviewed in detail including mesoporous silica, porous carbon, metal–organic frameworks, and covalent organic frameworks. The challenges of porous nanomaterials-based ECL systems are finally discussed, and the future perspectives are also anticipated. We hope this review could provide readers with a comprehensive understanding of ECL-related porous materials and new ideas. [ABSTRACT FROM AUTHOR]

Abstract: An easy and universal wall-jet configuration for microchip CE-ECL detection system was constructed and investigated in this work. Two detection modes of pre-column and post-column were applied to the above system. TPA, tramadol and lidocaine were chosen as model analytes to estimate the system in both modes. The important operational parameters such as the concentration of luminescent reagent and the distance between the separation outlet and the working electrode were optimally obtained and compared for the first time. [Copyright &y& Elsevier]

Abstract Here, the confined electrochemiluminescence (ECL) of luminol and hydrogen peroxide is achieved in vertically ordered silica mesochannels (SMCs) and applied to map the efflux of hydrogen peroxide from single living cells. The vertical alignment of SMCs on indium tin oxide (ITO) slides restricts the lateral diffusion of species generated in the ECL process. Accordingly, the cross-talk of luminescence intensity from nearby microregions is minimized for higher-spatial-resolution ECL imaging. The characterization of luminol ECL on these SMC-coated slides yields a detection range of hydrogen peroxide between 5 μM and 1 mM, providing high sensitivity in imaging the efflux of hydrogen peroxide from cells. Compared with the luminescence from individual cells on bare ITO slides, ~4-fold intensity is observed for SMC-coated ITO, suggesting a better electrode surface for single-cell ECL imaging. Graphical abstract Unlabelled Image Highlights • Confined ECL is achieved in vertically ordered silica mesochannels (SMCs). • The vertical alignment of SMCs restricts the lateral diffusion of species in ECL. • High-spatial-resolution ECL image is obtained to map the efflux from single cells. [ABSTRACT FROM AUTHOR]

Abstract An ultrasensitive and highly selective electrochemiluminescence (ECL) immunosensor is proposed for the detection of prostate specific antigen (PSA) based on multiple amplification via glucose oxidase (GOx) and platinum nanoparticles (Pt NPs) conjugated with polyglutamic acid (PGA). The proposed immunosensor has a wide linear range (1.0 pg/mL–150 ng/mL) and low detection limit (0.6 pg/mL) for PSA detection, which is due in part to the excellent catalytic activity of the Ab 2 -GOx-PGA-Pt NPs probe toward the luminol ECL reaction. Graphical abstract Unlabelled Image Highlights • Ab 2 -GOx-PGA-Pt NPs as signal-amplifying probe and Au NPs-luminol-LDH as ECL emitter were used to construct an immunosensor. • Ab 2 -GOx-PGA-Pt NPs have high catalytic activity to luminol ECL and increase the ECL signal. • The proposed ECL immunosensor achieved highly sensitive detection of PSA with a wide linear range. [ABSTRACT FROM AUTHOR]

Noble metal nanoparticles possess excellent optical and electrical properties, and have been widely used in the construction of biosensors and in surface-enhanced spectroscopy. Herein, we describe an enzyme-assisted ultra-sensitive biosensor with gold nanoparticle (GNP) dimers, based on a localized surface plasmon resonance (LSPR)-enhanced electrochemiluminescence (ECL) mechanism. CdS nanocrystals (NCs) acted as ECL emitters, and the GNP dimers were constructed by hybridization of DNA strands on the surface of an electrode modified with CdS NCs after an enzyme-assisted cyclic amplification process. The plasmon-coupling-induced electromagnetic field enhancement effects of the GNP dimers resulted in an increase in ECL intensity of as much as 6.3-fold under optimized conditions. Based on this LSPR-ECL sensor platform, the detection limit for microRNA-21 is as low as 3.6 fM with a wide linear range from 10 fM to 20 pM with good sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

In this work, we developed a visual ECL ratiometry on a closed bipolar electrode (BPE) for the detection of prostate specific antigen (PSA), prostate cancer biomarker. High efficient CdTe QDs was synthesized which emitted visualized red light at BPE cathode. Integrating with the anodic ECL emitters, luminol, visual emission of red-blue ratiometric ECL was achieved in BPE array chips. As a sensing probe, Au NRs nanocomposite was assembled on the surface of the cathode and acted as both the quencher of the CdTe QDs ECL and the promoter of the luminol ECL. After incubated with PSA, the Au NRs nanocomposite was peeled off from the electrode surface due to the specific recognition between PSA and aptamer. Consequently, the cathode ECL partly recovered and the anode ECL turned off. By measuring the ratio of visual ECL intensity at two poles of BPE, sensitive detection of PSA was achieved with a linear range from 1.0 ng/mL to 1.0 μg/mL and detection limit of 0.5 ng/mL (S/N=3). This strategy combining the BPE-ECL and visual ratiometry provided an accurate and intrinsic way for the sensing of PSA and showed good perspective in the clinical diagnosis. [ABSTRACT FROM AUTHOR]

A critical challenge in surface-based DNA assembly amplification is the reduced accessibility of DNA strands arranged on a heterogeneous surface compared to that in homogeneous solution. Here, a novel in situ surface-confined DNA assembly amplification electrochemiluminescence (ECL) biosensor based on DNA nanostructural scaffold was presented. In this design, a stem-loop structural DNA segment (Hairpin 1) was constructed on the vertex of DNA nanostructural scaffold as recognition probe. In the present of target DNA, the hairpin structure changed to rod-like through complementary hybridization with target DNA, resulting in the formation of Hairpin 1:target DNA. When the obtained Hairpin 1:target DNA met Hairpin 2 labeled with glucose oxidase (GOD), the DNA cyclic amplification was activated, releasing target DNA into homogeneous solution for the next recycling. Thus, the ECL signal of Ru(bpy) 3 2+ -TPrA system was quenched by H 2 O 2 , the product of GOD catalyzing glucose. As a result, this proposed method achieved a linear range response from 50 aM to 10 pM with lower detection limit of 20 aM. [ABSTRACT FROM AUTHOR]

Proximal metallic nanoparticles (NPs) could quench the electrochemiluminescence (ECL) emission of semiconductor quantum dots (QDs) due to Förster energy transfer (FRET), but at a certain distance, the coupling of light-emission with surface plasmon resonance (SPR) result in enhanced ECL. Thus, the modification strategies and distances control between QDs and metallic NPs are critical for the ECL intensity of QDs. In this strategy, a SPR enhanced ECL sensor based on DNA tetrahedral scaffolds modified platform was reported for the detection of telomerase activity. Due to the rigid three-dimensional structure, DNA tetrahedral scaffolds grafting on the electrode surface could accurately modulate the distance between CdS QDs and luminol labelled gold nanoparticles ( L -Au NPs), meanwhile provide an enhanced spatial dimension and accessibility for the assembly of multiple L -Au NPs. The ECL intensities of both CdS QDs (−1.25 V vs. SCE) and luminol (+0.33 V vs. SCE) gradually increased along with the formation of multiple L -Au NPs at the vertex of DNA tetrahedral scaffolds induced by telomerase, bringing in a dual-potential ECL analysis. The proposed method showed high sensitivity for the identification of telomerase and was successfully applied for the differentiation of cancer cells from normal cells. This work suggests that DNA tetrahedral scaffolds could serve as an excellent choice for the construction of SPR-ECL system. [ABSTRACT FROM AUTHOR]

Herein, a spatial-resolved electrochemiluminescene (ECL) ratiometry based on a closed biopolar electrode (BPE) is reported for the highly sensitive detection of prostate specific antigen (PSA). Au@g-C 3 N 4 NCs as one ECL emitter were firstly coated on the cathode of BPE, while the anode of the BPE served for calibration via another ECL substance, Ru(bpy) 3 2+ . The electroneutrality across the BPE makes the reactions on each pole of BPE electrically coupled. Thus one electrochemical sensing reaction at one pole of BPE could be quantified at both ends. A composite, Pt-PAMAM-DNAzyme was assembled on the surface of cathode via DNA hybridization between probe DNA and PSA aptamer. It acted as an ECL quencher of g-C 3 N 4 via resonance energy transfer (RET) and catalyzing the reduction of O 2 , the co-reactant of g-C 3 N 4 . Meanwhile, it could promote the ECL of Ru(bpy) 3 2+ at anode, since the catalytic reduction of O 2 at the cathode increased the faradiac current flowing through the BPE. Based on this signal composite, an ECL “off-on” phenomenon was observed at the cathode, after Pt-PAMAM-DNAzyme was “peeled off” by PSA. Conversely, at the anode, an “on-off” ECL changing was obtained. Therefore, a sensitive ratiometry for PSA detection was achieved with a linear range from 0.10 to 200 ng/mL. Since the two ECL emitters were physically separated, the ratiometric system was relatively simple and neither optical filters nor spectrometer were required. The strategy combining the ECL ratiometry and BPE broadens the applications of BPE-ECL and shows good perspective in clinical application. [ABSTRACT FROM AUTHOR]

A highly sensitive electrogenerated chemiluminescence (ECL) biosensor was developed on the basis of a closed bipolar electrode (BPE) apparatus for the analysis of prostate specific antigen (PSA). Bipolar modifications bring up two different stages of enhancement on the same electrode. Anodic enhancement was conducted by modifying gold nanoparticles (Au NPs) to catalyze the anodic ECL reaction between luminol and hydrogen peroxide. Cathodic introduction of thionine tagged PSA antibody led to a further pertinently enhancement synchronized with the PSA amount variation, because the existence of thionine greatly increased the rate of electron gains on cathode, leading to the corresponding acceleration of anodic ECL reaction. The more thionine modified target molecules were introduced, the faster luminol was oxidized, the higher faraday current approached, and sensitive quantification was realized in correlation with the responsive ECL intensity differences. The quantification resulted in a good determination range between 0.1 pg/mL and 0.1 µg/mL. This strategy mainly took advantage of the special structure of closed BPE to realize a simultaneous amplification on both ends of BPE. Moreover, the platform had a potential of providing a multi-functional strategy for the realization of other bio-detections by simply substituting the PSA sandwich structure with other bio-structures. [ABSTRACT FROM AUTHOR]

In this work, a dual-signaling electrochemiluminescence (ECL) ratiometric sensing approach for the detection of HL-60 cancer cells was reported for the first time. G-C 3 N 4 nanosheets and Ag–PAMAM–luminol nanocomposits (Ag–PAMAM–luminol NCs) were prepared and served as reductive–oxidative and oxidative–reductive ECL emitters respectively. DNA probe functionalized Ag–PAMAM–luminol NCs would hybridize with aptamers modified onto magnetic beads. In the presence of HL-60 cells, the aptamer would conjugate with the target cell and release Ag–PAMAM–luminol NCs. After magnetic separation, released Ag–PAMAM–luminol NCs would hybridize with capture DNA on g-C 3 N 4 nanosheets. ECL from g-C 3 N 4 nanosheets coated on ITO electrode at −1.25 V (vs SCE) could be quenched by Ag–PAMAM–luminol NCs due to the resonance energy transfer (RET) from g-C 3 N 4 nanosheets to Ag NPs. Meanwhile, Ag–PAMAM–luminol brought the ECL signal of luminol at +0.45 V (vs SCE). Thus, the concentration of HL-60 cancer cells could be quantified by both the quenching of ECL from g-C 3 N 4 nanosheets and the enhancement of ECL from luminol. By measuring the ratio of ECL intensities at two excitation potentials, this approach could achieve sensitive and reliable detection for cancer cells in a wide range from 200 cells/mL to 9000 cells/mL with the detection limit of 150 cells ( S / N =3). [ABSTRACT FROM AUTHOR]

Here we have developed a sensitive cancer cell amplified detection method which combined Au NPs enhanced electrochemiluminescence (ECL) of CdS nanocrystals (NCs) film, with isothermal circular amplification reaction of polymerase. In DNA circular amplification detection system, hairpin DNA beacon/Au NPs composite modified CdS NCs film was used as an ECL emitter. Messenger DNA is hybridized with the aptamer modified on magnetic beads (MBs) to form MB–Au bioconjugates. In the presence of HL-60 cell, the aptamer would conjugate with the glycoprotein at cell surface and messenger DNA sequence would be released. The released messenger DNA sequence was then introduced into the cycle amplification system to trigger circular polymerizations. This assay allows us to determine the released messenger DNA equivalent to 10 cells and exhibits a significant specificity for HL-60 cells. [ABSTRACT FROM AUTHOR]

An ITO bipolar array for electrochemiluminescence (ECL) imaging of H 2 O 2 was reported. Silver nanoparticle-reduced graphene oxide (AgNP-rGO) composites were simultaneously coated on the cathodes of a bipolar array via a one-step electrodeposition approach. Compared to naked ITO, the above composites exhibited notable electrocatalytic activity to H 2 O 2 . The concentration of H 2 O 2 could be indicated by the ECL image of Ru(bpy) 3 2 + /2-(dibutylamino) ethanol (DBAE) at anodes based on charge balance. This chip system, not only provides a fast manner to prepare nanocomposites on bipolar electrodes (BPEs), but also can realize high-throughput visual detection. [ABSTRACT FROM AUTHOR]

Abstract: This work demonstrates an aptasensor for ultrasensitive electrochemiluminescence (ECL) detection of thrombin based on an “off–on–off” approach. The system is composed of an Eu3+-doped CdS nanocrystals (CdS:Eu NCs) film on glassy carbon electrode (GCE) as ECL emitter. Then gold nanoparticles (AuNPs) labeled hairpin-DNA probe (ssDNA1) containing thrombin-binding aptamer (TBA) sequence was linked on the NCs film, which led to ECL quenching (off) as a result of Förster-resonance energy transfer (FRET) between the CdS:Eu NC film and the proximal AuNPs. Upon the occurrence of hybridization with its complementary DNA (ssDNA2), an ECL enhancement (on) occurred owing to the interactions of the excited CdS:Eu NCs with ECL-induced surface plasmon resonance (SPR) in AuNPs at large separation. Thrombin could induce ssDNA1 forming a G-quadruplex and cause the AuNPs to be close to CdS:Eu NCs film again, which resulted in an enhanced ECL quenching (off). This “off–on–off” system showed a maximum 7.4-fold change of ECL intensity due to the configuration transformation of ssDNA1 and provides great sensitivity for detection of thrombin in a wide detection range from 50aM to 1pM. [Copyright &y& Elsevier]

Abstract: Here we report a novel approach for the detection of adenosine in cancer cells by electrochemiluminescence (ECL) on a wireless indium tin oxide bipolar electrode (BPE). In this approach, ferrocene (Fc) which is labeled on adenosine aptamer is enriched on one pole of the BPE by hybridization with its complementary DNA (ssDNA) and oxidized to Fc+ under an external voltage of 5.0V at the two ends of BPE. Then, a reversed external voltage was added on the BPE, making Fc+ enriched pole as cathode. The presence of Fc+ promotes the oxidation reaction on the anodic pole of the BPE, resulting in a significant increase of ECL intensity using Ru(bpy)3 2+/tripropylamine (TPA) system as test solution. The presence of target adenosine was reflected by the ECL signal decrease on the anodic pole caused by the target-induced removal of ferrocene-aptamer on the cathodic pole. The decrease of ECL signal was logarithmically linear with the concentration of ATP in a wide range from 1.0fM to 0.10μM. This ECL biosensing system could accurately detect the level of adenosine released from cancer cells. [Copyright &y& Elsevier]

Abstract: In this work, we firstly enunciated the presence of synergy effect between the electron and energy transfer in an electrochemiluminescence (ECL) system involving the CdS NCs and Au NPs, based on which an amplified ECL biosensor was constructed for sensitive detection of DNA–protein interactions. Specifically, Au NPs modified on electrode, following by assembled probe DNA. Then the modified GCE was hybridized with SiO2@CdS/DNA conjugates. With DNA duplex as a rigid spacer, Au NPs could not only accelerate the electron transfer but also produce the surface plasma resonance upon excited ECL of CdS NCs. However, the enhanced ECL could be greatly suppressed by the binding of target protein. The prepared biosensor possesses excellent analytical performance with the linear range of target protein from 0.015 to 150nM. [Copyright &y& Elsevier]

Abstract: We report here a sensitive electrochemiluminescence (ECL) approach for detection of HL-60 cancer cells based on Au nanoparticles (NPs) enhanced ECL of CdS nanocrystal (NC) film supplemented by magnetic separation. In this approach, capture DNA-1 modified CdS NC film was used as ECL emitter. Capture DNA-2, which is labeled with Au NP, is hybridized with the aptamer modified on magnetic beads (MBs) to form MB-Au NP bioconjugates. In the presence of HL-60 cells, the aptamer would conjugate with the glycoprotein at cell surface and Au NPs labeled capture DNA-2 would be released. After magnetic separation, the released Au NPs labeled capture DNA-2 is hybridized with the capture DNA-1 to enhance the ECL signal of CdS NC film. This approach could sensitively detect HL-60 cells with a linear calibration range from 20 to 1.0×106 cells/mL. [Copyright &y& Elsevier]

Abstract: Aiming to find an alternative electrochemiluminescence (ECL) quenching route of high efficiency, biocatalytic precipitation (BCP) was firstly coupled with ECL for investigating its insulating effect on ECL. Experimental data revealed that an insulating layer could be formed via BCP onto the electrode surface, inhibiting the reaction between the coreactant and luminophore and thereby impairing the ECL emission dramatically. Since the extent of insulating effect associated strongly with analyte concentration, a new ECL biosensor was successfully realized. In a model horseradish peroxidase (HRP)-based system, the fabricated biosensor possessed high sensitivity and wide linear range from 1.0×10−10 M to 1.0×10−6 M for H2O2 determination with a detection limit of 4×10−11 M (S/N =3). This method has great potential in extending the application of ECL biosensor for various bioanalytes. [Copyright &y& Elsevier]

Abstract: The cationic luminescence probe, tris(2,2′-bipyridyl)ruthenium(II) complex ([Ru(bpy)3]2+), was incorporated into laponite-modified glassy carbon electrode (GCE) via two strategies, namely, the adsorption and intercalation methods. These two incorporation methods resulted in different microenvironment for the immobilized [Ru(bpy)3]2+ within laponite as well as the different host–guest and guest–guest interactions. Herein, cyclic voltammetry and electrochemiluminescence (ECL) were innovatively performed to monitor the interactions. Tripropylamine (TPA) was used as coreactant in the electrochemical and ECL system. [Copyright &y& Elsevier]

CRISPR-Cas12a system exhibits tremendous potential in accurate recognition and quantitation of nucleic acids and non-nucleic-acid targets thanks to the discovery of its cleavage capability toward single-stranded DNA (ssDNA). In this study, we developed an efficient electrochemiluminescence (ECL) sensing platform based on CRISPR-Cas12a for the analysis of adenosine triphosphate (ATP). In the presence of the target, the successful release of the DNA activator is specially recognized by Cas12a-crRNA duplex and activates the cleavage of ferrocene (Fc) labeled–ssDNA (Fc-ssDNA) modified on the cathode of bipolar electrode (BPE), resulting in a decrease of ECL intensity of [Ru(bpy) 3 ]2+/TPrA in the anodic cell of BPE. By means of the unique combination of Cas12a with ECL technique based on BPE, it can convert the recognition of target ATP into a detectable ECL signal. The detection limit of ATP was determined to be 0.48 nM under the optimal conditions. This work will expand the application of CRISPR-Cas detection system and propose a potential method for the analysis of non-nucleic-acid targets. Sensing mechanism for ATP detection. [Display omitted] • The paper provides an efficient ECL biosensing system based on CRISPR-Cas12a for the determination of ATP. • CRISPR-Cas12a can convert the recognition of target ATP into detectable ECL signals on bipolar electrodes. • Sensitive quantitative analysis of ATP was achieved with the detection limit of 0.48 nM. [ABSTRACT FROM AUTHOR]

• This paper proposed an ECL biosensor based on polymer dots for ultrasensitive detection of miRNA-122. • A novel carboxyl functionalized Pdot was prepared by nanoprecipitation without exogenous functionalized reagents. • The biosensor employed two-step signal amplification strategy including enzyme assisted recycle and rolling circle amplification. • This work will further expand the applications of Pdots nanomaterials in the ECL bioanalysis. An electrochemiluminescence (ECL) sensing platform for ultrasensitive detection of miRNA-122 was developed by integrating novel emitters of polymer dots (Pdots) and signal amplification strategies. Firstly, we synthesized a novel polymer with carboxyl group which consisted of fluorene derivate and benzothiadiazole, corresponding Pdots materials were also prepared by nanoprecipitation method. Subsequently, an ECL biosensor based on the Pdots for miRNA-122 detection was constructed, which combines the amplification of duplex-specific nuclease (DSN)-assisted target recycling and rolling circle amplification (RCA) in-situ on the electrode. After the two-step amplification, amounts of ferrocene modified DNA (Fc-DNA) were captured on the electrode, which could quench the ECL signal of the Pdots. Ultimately, the proposed sensor presented a wide linear range of 0.1 fM to 100 pM and a low detection limit of 36 aM to miRNA-122. This work not only propose a universal paradigm for nucleic acid detection with good specificity and high sensitivity, but also provide an approach for designing novel Pdots to construct ECL sensor conveniently. [ABSTRACT FROM AUTHOR]

Herein, a facile top-down approach and a post-synthetic etching strategy were reported to prepare high-quality sulfur quantum dots (H-SQDs), which were first discovered with a boosted anodic electrochemiluminescence (ECL) emission in an aqueous solution. Elaborate investigations demonstrated that the significantly improved ECL properties of H-SQDs were attributed to the reduced size for inherent brightness, the highly passivated surface, and enhanced charge injection/transfer capacities after the post-synthetic hydrogen peroxide etching. The underlying anodic ECL mechanism and the redox nature of H-SQDs were studied in detail for the first time, indicating a direct oxidation ECL mechanism with tri-n-propylamine as the "oxidation-reduction" coreactant. Beyond that, the as-obtained H-SQDs also featured low cost, remarkable monodispersity, excellent water-solubility, and good biocompatibility, illustrating their great potential in ECL bioanalysis. As a proof-of-concept, H-SQDs, an emerging ECL emitter with high ECL efficiency, was utilized to construct an "off-on" ECL biosensor for sensitive glutathione (GSH) assay. This work not only promotes the exploration of novel ECL emitters, but also provides a new perspective for the application of SQDs-based ECL biosensor in clinical diagnosis. [ABSTRACT FROM AUTHOR]

Electrochemiluminescence resonance energy transfer (ERET) is a powerful analytical strategy based on the resonance energy transfer (RET) between an efficient electrochemiluminescence (ECL) emitter and a spectrally matched energy acceptor. Compared with fluorescence resonance energy transfer (FRET), ERET is more intriguing because it can eliminate the interference from unselective photoexcitation and the scattered light. In recent years, ERET has drawn wide concern for the analysis of the trace amounts of different targets due to its remarkable advantages of high sensitivity, inexpensive instruments and excellent controllability. This review detailly discuss the main mechanisms for the ERET process between the donor-acceptor pairs. We also comment on the latest progress of signaling strategies in the ERET process and their applications for the bioanalysis of small molecules, proteins and nucleic acids. Finally, perspectives and challenges in this field are also discussed. • Recent advances in electrochemiluminescence resonance energy transfer (ERET) are reviewed. • The fundamentals and biological applications of the ERET strategies are discussed. • ERET systems using various energy acceptors are illustrated. • The future prospects of ERET are presented. [ABSTRACT FROM AUTHOR]