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Herein, a supersensitive biosensor was constructed by using graphitic carbon nitride with a carbon vacancy (V

Aggregation-induced electrochemiluminescence (AIECL) has attracted extensive interest due to the significant increase in ECL response by restricting free intramolecular rotation and torsion, but traditional AIECL emitters suffer from limited ECL efficiency, high cost, and complex synthetic steps, dramatically limiting their applications. Herein, novel Al(III)-Cbatpy metal-organic gels (Al(III)-Cbatpy-MOGs) with nanofiber morphology and ultrarapid coordination of Al

In this study, upon potassium (K) element doping, the electrochemiluminescence (ECL) excitation potential of graphitic carbon nitride (g-C

Herein, a novel single-enzyme-assisted dual recycle amplification strategy based on T7 exonuclease (T7 Exo) and a strand-displacement reaction (SDR) was designed to fabricate a photoelectrochemical (PEC) biosensor for sensitive microRNA-141 (miRNA-141) detection with the use of laminar bismuth tungstate (Bi2WO6) as photoactive material. Compared with a traditional enzyme-assisted dual recycle amplification strategy, the presented method could effectively refrain the enzyme interference reaction, reduce environmental sensitivity, and save cost. Here, hairpin DNA1 (H1) decorated on magnetic beads (MB) hybridized with target miRNA-141 to form an H1/miRNA-141 heteroduplex. With the introduction of hairpin DNA2 (H2)-labeled SiO2 (H2-SiO2), SDR was triggered between H2-SiO2 and H1, thus miRNA-141 was displaced from the H1/miRNA-141 heteroduplex and an H1/H2-SiO2 duplex was formed, realizing the reuse of the target. In the presence of T7 Exo, the H1/H2-SiO2 duplex was digested with the release of output DNA-SiO2. To enhance the target conversion rate, H1-MB was intactly released and cycled, which could initiate more T7 Exo digestion and free abundant output DNA-SiO2. Through such a process, a tiny miRNA-141 could induce substantial output DNA-SiO2, effectively improving the target amplification efficiency and detection sensitivity of a PEC biosensor. Furthermore, Bi2WO6 was modified on an electrode to provide a superior initial PEC signal due to its excellent electronic transformation capacity. With the introduction of output DNA-SiO2, the hairpin structure of H3 on the electrode was opened, making SiO2 close to the electrode surface, which significantly decreases the PEC signal. This work first established the PEC biosensor featuring a single-enzyme-assisted dual recycle amplification process for sensitive detection of biomarkers.

Here, we fabricated a novel photoelectrochemical (PEC) aptasensor based on Br,N-codoped TiO2/CdS quantum dots (QDs) sensitization structure with excellent energy level arrangement for supersensitiv...

In this study, sulfur quantum dots (SQDs) with superior near-infrared electrochemiluminescence (ECL) performance were synthesized by the H2O2-assisted top-down approach. Through H2O2 etching, the size and dispersity of SQDs were adjusted, reducing the aggregation-caused quenching effect and obviously promoting the ECL performance. Using the obtained SQDs as an emitter, a super-sensitive ECL biosensor of microRNA-21 (miRNA-21) detection was constructed, which was based on an efficient DNA walking machine with triple-stranded DNA (tsDNA) nanostructures as tracks. Compared with the common single-stranded DNA or double-stranded DNA, the tsDNA nanostructures on the electrode interface could avert probe entanglement and decrease local overcrowding effects. The walking efficiency of the DNA walking machine was also improved and the signal-amplification efficacy was greatly enhanced, which was benefited from the fact that tsDNA nanostructures were highly rigid scaffolds and provided orderly tracks for the DNA walking machine to walk. Thus, the designed ECL biosensor demonstrated outstanding performance for miRNA-21 detection in the concentration range of 20 aM to 1 nM with a low detection limit of 6.67 aM. Remarkably, this work enriched the application of pure element quantum dots in the ECL field and offered a new avenue for ultra-sensitive detection in clinical and biochemical analysis.

In this work, an ultrasensitive photoelectrochemical (PEC) assay was established for sensitive DNA detection based on a novel SnS

In this work, a kind of novel nitrogen doped hydrazide conjugated carbon dots (NHCDs) with strong anodic electrochemiluminescence (ECL) at a low excitation potential were synthesized via a one-step solvothermal approach and applied to construct biosensor for rapid cancer cell detection. The nitrogen doping induced a shift of the highest occupied molecular orbital (HOMO) to the upper energy level thus lowered the anodic ECL excitation potential of carbon dots. Especially, comparing to nondoped hydrazide conjugated carbon dots, NHCDs exhibited 2.5-fold high ECL quantum efficiency because the lower potential could reduce notably the side reactions in the ECL process. Using the high-performance NHCDs to functionalize the electrode surface, a brief ECL biosensor was fabricated to detect the cell-secreted hydrogen peroxide, which could rapidly distinguish cancer cells from normal cells. What is more, the prepared NHCDs, as the combination of low excitation potential, strong ECL emission, and good biocompatibility, were expected to be popular luminophors for clinical diagnose of cancer and monitoring the pharmacodynamics of anticancer drugs.

In this work, a ferrocene (Fc)-driven light switch biosensor for ultrasensitive detection of amyloid-β (Aβ) was designed by utilizing the highly efficient electrochemiluminescent nanomaterials of silver nanoclusters/titanium oxide nanoflowers (Ag NCs/TiO2 NFs) as signal labels. Through combining the TiO2 NFs as the coreaction accelerator and dissolved O2 as the intrinsic coreactant to in situ generate the strong oxidizing intermediate radical OH•, the electrochemiluminescence (ECL) of Ag NCs on the TiO2 NFs surface could be significantly promoted in comparison with that of pure Ag NCs in solution. Further, Fc-labeled DNA as the ECL quenching probe was introduced to dramatically restrain the ECL emission of nanomaterials, which facilitated improving the sensitivity of the prepared biosensor to a large extent. Surprisingly, tiny amounts of target protein could be recognized by the immunoreaction-induced DNA nanostructure for outputting numerous secondary-target DNAs, which further triggered the release of F...

Here, a target-induced three-dimensional DNA network structure (T-3D Net) produced by catalytic hairpin assembly (CHA) was proposed as a novel signal amplifier to fabricate an ultrasensitive electrochemiluminescence (ECL) biosensor for microRNAs detection. Usually, conventional CHA can produce only one output DNA in each target cycle, while the proposed strategy could produce multiple output DNA by using DNA-functionalized magnetic beads (MBs) and gold nanoparticles (AuNPs) to form T-3D Net. Then, the T-3D Net with high loading capacity could be completely collapsed by dissolving AuNPs to efficiently convert trace microRNA-21 into a large amount of output DNA. Furthermore, the nanocomposite containing Ru(bpy)

In the present work, we first found that mercury ion (Hg(2+)) has an efficient quenching effect on the electrochemiluminescence (ECL) of N-(aminobutyl)-N-(ethylisoluminol) (ABEI). Since we were inspired by this discovery, an aptamer-based ECL sensor was fabricated based on a Hg(2+) triggered signal switch coupled with an exonuclease I (Exo I)-stimulated target recycling amplification strategy for ultrasensitive determination of Hg(2+) and mucin 1 (MUC1). Concretely, the ECL intensity of ABEI-functionalized silver nanoparticles decorated graphene oxide nanocomposite (GO-AgNPs-ABEI) was initially enhanced by ferrocene labeled ssDNA (Fc-S1) (first signal switch "on" state) in the existence of H2O2. With the aid of aptamer, assistant ssDNA (S2) and full thymine (T) bases ssDNA (S3) modified Au nanoparticles (AuNPs-S2-S3) were immobilized on the sensing surface through the hybridization reaction. Then, via the strong and stable T-Hg(2+)-T interaction, an abundance of Hg(2+) was successfully captured on the AuNPs-S2-S3 and effectively inhibited the ECL reaction of ABEI (signal switch "off" state). Finally, the signal switch "on" state was executed by utilizing MUC1 as an aptamer-specific target to bind aptamer, leading to the large decrease of the captured Hg(2+). To further improve the sensitivity of the aptasensor, Exo I was implemented to digest the binded aptamer, which resulted in the release of MUC1 for achieving target recycling with strong detectable ECL signal even in a low level of MUC1. By integrating the quenching effect of Hg(2+) to reduce the background signal and target recycling for signal amplification, this proposed ECL aptasensor was successfully used to detect Hg(2+) and MUC1 sensitively with a wide linear response.

Here, a novel "light-switch" molecule of Ru (II) complex ([Ru(dcbpy)2dppz](2+)-DPEA) with self-enhanced electrochemiluminescence (ECL) property is proposed, which is almost nonemissive in aqueous solution but is brightly luminescent when it intercalates into DNA duplex. Owing to less energy loss and shorter electron-transfer distance, the intramolecular ECL reaction between the luminescent [Ru(dcbpy)2dppz](2+) and coreactive tertiary amine group in N,N-diisopropylethylenediamine (DPEA) makes the obtained "light-switch" molecule possess much higher light-switch efficiency compared with the traditional "light-switch" molecule. For increasing the loading amount and further enhancing the luminous efficiency of the "light-switch" molecule, biotin labeled DNA dendrimer (the fourth generation, G4) is prepared from Y-shape DNA by a step-by-step assembly strategy, which provides abundant intercalated sites for [Ru(dcbpy)2dppz](2+)-DPEA. Meanwhile, the obtained nanocomposite (G4-[Ru(dcbpy)2dppz](2+)-DPEA) could well bind with streptavidin labeled detection antibody (SA-Ab2) due to the existence of abundant biotin. Through sandwiched immunoreaction, an ECL immunosensor was fabricated for sensitive determination of N-acetyl-β-d-glucosaminidase (NAG), a typical biomarker for diabetic nephropathy (DN). The detemination linear range was 0.1 pg mL(-1) to 1 ng mL(-1), and the detection limit was 0.028 pg mL(-1). The developed strategy combining the ECL self-enhanced "light-switch" molecular and DNA nanotechnology offers an effective signal amplification mean and provides ample potential for further bioanalysis and clinical study.

The DNA nanocrane with functionalized manipulator and fixed-size base offered a programmable approach to modulate the luminous efficiency of copper nanoclusters (Cu NCs) for achieving remarkable electrochemiluminescence (ECL) enhancement, further the Cu NCs as signal label was constructed in biosensor for ultrasensitive detection of microRNA-155. Herein, the DNA nanocrane was first constructed by combining binding-induced DNA assembly as manipulator and tetrahedral DNA nanostructure (TDN) as base, which harnessed a small quantity of specific target (microRNA (miRNA)-155) binding to trigger assembly of separate DNA components for producing numerous AT-rich double-stranded DNA (dsDNA) on the vertex of TDN. Upon the incubation of Cu2+ on the AT-rich dsDNA, each DNA-stabilized Cu NCs probe could be in situ electrochemically generated on an individual TDN owing to the A-Cu2+-T bond. Thus, the generation of Cu NCs was highly regulated with AT-rich dsDNA as the template, and its lateral distance was tuned by the...

Electrochemiluminescence (ECL) with high sensitivity and excellent controllability provides a promising approach for ultrasensitive detection of multiple biomarkers. However, the detection for multiple types of biomarkers on a single interface remains a considerable challenge owing to the functional differentiation of different types of biomarkers. Herein, we utilized "on-off-on" switching, target-induced cleavage of peptide, and TdT (terminal deoxynucleoside transferase)-mediated extension successfully constructing a novel ECL biosensor for the ultrasensitive detection of microRNA-141 (miRNA-141) and matrix metalloproteinase-2 (MMP-2). Importantly, the dual biomarkers are related with several identical cancers, which endow the biosensor with diagnostic accuracy and efficiency. In this protocol, target 1 (miRNA-141) first hybridized with probe DNA (pDNA) assembled on CdS QDs modified sensing surface. Afterward, miRNA-141 captured trigger DNA (tDNA) to generate a long ssDNA nanotail via TdT-mediated DNA polymerization. Then the forming ssDNA could capture abundant Fc-peptide-ssDNA conjugates through the hybridization reaction, the ECL intensity quenched significantly due to the efficient quenching effect of Fc to CdS QDs, realizing the ultrasensitive detection of miRNA-141 with a detection limit of 33 aM (S/N = 3). After incubated with target 2 (MMP-2) which specifically cleaved the Fc-peptide-ssDNA conjugates causing the releasing of Fc from the sensing surface, the ECL intensity had an obvious enhancement, achieving the ultrasensitive analysis of MMP-2 with a detection limit of 33 fg·mL

Here, a novel Ru(II)-organic complex (Ru-PEI-ABEI) with high electrochemiluminescence (ECL) efficiency was proposed to construct a sensitive quenching-typed ECL biosensor for C-peptide (C–P) measurement based on the double quenching effect of dopamine (DA). The high ECL efficiency of Ru-PEI-ABEI was originated from the dual intramolecular self-catalysis including intramolecular coreaction between polyethylenimine (PEI) and Ru(bpy)2(mcbpy)2+, and intramolecular ECL resonance energy transfer (ECL-RET) from N-(aminobutyl)-N-(ethylisoluminol) (ABEI) to Ru(bpy)2(mcbpy)2+, which would generate a strong initial ECL signal. Through sandwiched immunoreaction and 3D DNA walking machine, a certain amount of target C–P was converted to a large amount of intermediate DNA that could further trigger hybridization chain reaction (HCR) to introduce into massive DA which not only could quench the ECL of Ru(bpy)2(mcbpy)2+, but also quench the ECL of ABEI. Thus, the double quenching effect of DA would effectively quench the ...

In this study, an electrochemiluminescence (ECL) regenerated biosensor was reported to sensitively detect microRNA through 3D DNA walking machine and "on-off-super on" strategy. First, 3D DNA walking machine with higher efficiency of payload releasing and superior signal amplification than those of the traditional DNA walking machine was initially introduced in the ECL system for converting target microRNA to intermediate DNA and achieving significant signal amplification. Second, the distance between CdS:Mn quantum dots and Au nanoparticles was increased with the hybridization of intermediate DNA and Au nanoparticles modified S2, which weakened the energy transfer for ECL signal recovering and excited the surface plasma resonance for further enhancing the signal to construct the on-off-super on biosensor. Such an on-off-super on strategy not only reduced the ECL background signal but also increased the detection sensitivity. Impressively, the elaborately designed biosensor could be regenerated by Lambda exonuclease hydrolyzing the intermediate DNA to make Au nanoparticles modified S2 recover to their original hairpin structure. With the amazing signal amplification of 3D DNA walking machine and sensitive distance control of the on-off-super on strategy, the biosensor showed excellent performance for microRNA-141 detection with a low detection limit of 3.3 fM and could be applied to human prostate cancer cells analysis. Furthermore, this work established a foundation to apply 3D walker in ECL methodology and provided an effective way for analysis of other microRNA or cancer cells.

Herein, we fabricated a novel electrochemiluminescence (ECL) biosensor for ultrasensitive detection of mucin 1 (MUC1) based on a three-dimensional (3-D) DNA nanomachine signal probe powered by protein-aptamer binding complex. The assembly of 3-D DNA nanomachine signal probe achieved the cyclic reuse of target protein based on the protein-aptamer binding complex induced catalyzed hairpin assembly (CHA), which overcame the shortcoming of protein conversion with enzyme cleavage or polymerization in the traditional examination of protein. In addition, CoFe2O4, a mimic peroxidase, was used as the nanocarrier of the 3-D DNA nanomachine signal probe to catalyze the decomposition of coreactant H2O2 to generate numerous reactive hydroxyl radical OH• as the efficient accelerator of N-(aminobutyl)-N-(ethylisoluminol) (ABEI) ECL reaction to amplify the luminescence signal. Simultaneously, the assembly of 3-D DNA nanomachine signal probe was executed in solution, which led to abundant luminophore ABEI be immobilized a...

A self-enhanced electrochemiluminescence (ECL) reagent, synthesized by covalently linking bis(2,2'-bipyridyl)(4'-methyl-[2,2']bipyridinyl-4-carboxylicacid) ruthenium(II) (Ru(bpy)2(mcbpy)(2+)) with tris(3-aminopropyl)amine (TAPA), has been chosen as precursor to prepare nanorods ([Ru(bpy)2(mcbpy)(2+)-TAPA]NRs) with high luminous efficiency via a solvent-evaporation-induced self-assembly procedure. Due to the shorter electron-transfer path and less energy loss, the intramolecular reaction between the luminescent Ru(bpy)2(mcbpy)(2+) and coreactive tertiary amine group in TAPA has shown improved luminous efficiency compared with the common intermolecular ECL reactions. Moreover, using the electrochemiluminescent Ru(II)-based complex as precursor to directly prepare a nanostructure with high electro-active surface area is a more effective and convenient method for enhancing the immobilized amount of Ru(II)-based complex in the construction of biosensors compared with the traditional immobilized methods. Meanwhile, the obtained nanorods could be further functionalized easily, owing to their positive electrical property and the amino group on the surface. Here, Pt nanoparticles functionalized [Ru(bpy)2(mcbpy)(2+)-TAPA]NRs are used to load the detection antibody (Ab2). In addition, the Au/Pd dendrimers (DRs) with hierarchically branched structures are synthesized to immobilize capture antibody (Ab1) with increased amount. Based on sandwiched immunoreactions, a simple and sensitive "signal-on" immunosensor is constructed for the detection of N-acetyl-β-d-glucosaminidase (NAG), a biomarker of diabetic nephropathy, with excellent linearity in concentrations from 1 ng mL(-1) to 0.5 pg mL(-1) and a detection limit of 0.17 pg mL(-1).