Electrochemiluminescence Research Articles

Dual-Mode Immunoassay Constructed by Water-Induced Perylene Diimide Supramolecular Self-Assembly and Enzymatic Biocatalytic Precipitation Strategy.

A water-induced electron-deficient dye, the supramolecule perylene diimide (PDI), has been identified recently. PDI possesses advantages such as easy reduction, nontoxicity, low cost, and simple preparation, making it a promising candidate for electrochemiluminescence (ECL) sensing platforms. In this study, a series of PDI supramolecular systems with morphological changes were prepared by utilizing water molecules to induce PDI self-assembly. This method improves the π-π stacking interactions between PDI molecules and effectively mitigates the aggregation-caused quenching (ACQ) effect on the luminous efficiency of the coplanar polycyclic aromatic hydrocarbon PDI. It is noteworthy that excellent ECL emission performance of the PDI supramolecular system was observed at -0.4 V. This low excitation potential aids in preserving antigen-antibody bioactivity and ensures accurate identification of the immune response. As a proof of concept, a dual-mode immunosensing platform for carcinoembryonic antigen (CEA) detection was constructed using an enzymatic biocatalytic precipitation (EBCP) strategy. The dual-mode immunosensor exhibited good detection performance in the concentration range of 0.001-80 ng·mL-1, presenting an advanced bioprotective analytical method for CEA detection.

A dual-potential electrochemiluminescence sensor for glutamate pyruvate transaminase detection based on AgNPs/N, S-GQDs modified paper-based electrode

The liver, one of the most vital organs in the human body, relies on glutamate pyruvate transaminase (GPT) as a sensitive indicator of hepatocellular injury, making it a cornerstone parameter in liver function assessment. This study employed a paper-based electrode modified with AgNPs/N, S-GQDs synthesized via pyrolysis to construct an AgNPs/N, S-GQDs paper-based electrode reaction system for detecting GPT activity across two potential ranges. This approach involved utilizing electrochemiluminescence (ECL) detection to indirectly measure GPT levels by detecting the NADH generated through GPT transamination, as well as investigating the relationship between GPT activity and the ECL intensity of the reaction system directly. Experimental results demonstrated a robust linear correlation between GPT activity and the ECL intensity of the reaction system within the ranges of 1U/L to 1000U/L and 5U/L to 200U/L, with detection limits of 0.24U/L and 3.73U/L, respectively. By establishing methods for indirect and direct GPT detection within the same reaction system across different scan ranges, this study enhances detection accuracy. The proposed method not only offers a wide linear range and low detection limits for GPT detection but also exhibits notable advantages in terms of detection efficiency compared to other methods, showcasing promising applications in the diagnosis and evaluation of liver function-related diseases.

Zero-Background Dual-Mode Closed Bipolar Electrode Electrochemiluminescence Biosensor Based on ZnCoN-C Potential Regulation for Ultrasensitive Detection of Ochratoxin A.

In this work, the relationship between electrochemiluminescence (ECL) signal and driving voltage was first studied by self-made reduced and oxidized closed bipolar electrodes (CBPEs). It was found that when the driving voltage was large enough, the maximum ECL signals for the two kinds of CBPEs were the same but their required drive voltages were different. Zinc cobalt nitrogen doped carbon material (ZnCoN-C) had an outstanding electric double layer (EDL) property and conductivity. Therefore, it could significantly reduce the driving voltage of two kinds of CBPE systems, reaching the maximum ECL signal of Ru(bpy)32+. Interestingly, when the ZnCoN-C modified electrode reached the maximum ECL signal, the bare electrode signal was zero. As a proof-of-concept application, a zero-background dual-mode CBPE-ECL biosensor was constructed for the ultrasensitive detection of ochratoxin A (OTA) in beer. Considering that beer samples contained a large number of reducing substances, a reduced CBPE system was selected to build the biosensor. Furthermore, a convenient ECL imaging platform using a smartphone was built for the detection of OTA. This work used a unique EDL material ZnCoN-C to regulate the driving voltage of CBPE for the first time; thus, a novel zero-background ECL sensor was constructed. Further, this work provided a deeper understanding of the CBPE-ECL system and opened a new door for zero-background detection.

Low-potential anodic electrochemiluminescence of terbium metal-organic frameworks for selective microRNA-155 detection

High excitation potential is recognized as a harmful factor for the biological activity of biomacromolecules, such as proteins and nucleic acids, in electrochemiluminescence (ECL) biosensing. Developing low-potential ECL luminophores is vital for improving ECL accuracy in actual sample sensing. In this work, based on porous metal-organic framework (MOF) structure with multiple active sites and energy transfer between the excited ligands and Ln nodes, we designed a series of Ln-MOFs and observed ECL emission at low potential, providing a novel method to realize low-potential ECL. The MOF nanoemitters were prepared using 1,3,5-tri (4-carboxyphenyl)benzene ligand and several lanthanide ions as nodes through mild hydrothermal reaction. Interestingly, strong ECL emission at +0.75 V of peak potential was observed in the ECL-potential curve of Tb-based MOF using 2,2′,2″-nitrilotriethanol as coreactant, which was beneficial for reducing background interference in biosensing, and this ECL emission was attributed to the energy transfer between Tb and excited ligand. This low-potential ECL was then applied to construct an ECL biosensor with newly developed Cas12a-based method for selective detection of microRNA-155 without the help of strand displacement or reverse transcription. For this ECL system, the limit of detection was 0.78 nM, and the overall detection time was 2.5 h. The Ln-MOF nanoemitter provides a robust ECL platform to selectively detect various targets by integrating new bio-related techniques.

A visual biosensor chip based on the enhanced electrochemiluminescence with low triggered potential for ochratoxin A detection

The introduction of a coreaction accelerator can effectively enhance the electrochemiluminescence (ECL) response. However, the development of coreaction accelerators for ruthenium (Ru) complex, one of the most widely used ECL emitters, is still in its early stages. In this study, the application of BiOI as a multifunctional coreaction accelerator for the Ru/N-Butyldiethanolamine (DBAE) system for the first time. The BiOI microspheres not only exhibit a fivefold enhancement in ECL signal but also reduce the trigger potential, potentially mitigating interference factors associated with high applied voltage. The nanoflower structure of BiOI microspheres also facilitates the immobilization of Ru(bpy)32+. Building upon this, a portable visual biosensor chip was developed for the detection of ochratoxin A (OTA). The biosensor chip comprises a sensing cell and a reporting cell. When OTA toxins are detected in the microenvironment, the aptamers attached to the surface of the sensing cell are released, resulting in a decrease in impedance on the electrode surface. Consequently, the ECL emission from Ru(bpy)32+/BiOI microspheres modified onto the reporting cell is enhanced. The concentration of OTA can be determined by analyzing the intensity change of ECL imaging, eliminating the need for specific instruments. This visual ECL biosensor chip offers the advantages of portability, ease of operation, low cost, and demonstrates excellent performance in detecting beer samples.

Highly sensitive ECL detection of miRNA based on self-generated coreactant and target-induced catalyzed hairpin assembly

BackgroundRecently, various techniques have been developed to accurately and sensitively detect tumor biomarkers for the early diagnosis and effective therapy of cancer. The electrochemiluminescence (ECL) method holding outstanding features including high sensitivity, ease of operation, and spatiotemporal controllability exhibited great potential for DNA/RNA detection, immunoassay, cancer cell detection, and environmental analysis. However, a glaring problem of ECL approaches is that the layer-by-layer modification on the electrode leads to poor stability and sensitivity of the sensors. Therefore, new simple and efficient methods for electrode modification which can effectively improve the ECL signal have attracted more and more research interests. ResultsBased on the dual amplification strategy of target-induced CHA and nanocomposite probes leading to self-generated co-reactant (H2O2), we proposed a highly sensitive miRNA-ECL detection system. The introduction of the target miRNA-21 triggers the CHA cycle amplification of DNA1 and biotin-modified DNA2, releasing the target miRNA-21 sequence for the target cycle reaction. After the reaction, the newly introduced DNA2 was combined with Au NPs modified with SA and Glucose oxidase (GOD). In the presence of oxygen, glucose was decomposed by GOD to produce H2O2, and then H2O2 was immediately catalyzed by the Hemin/G-quadruplex at the double-stranded end of the CHA product to produce a large amount of O2−•. As a co-reactant of luminol, the ECL signal was significantly enhanced, thereby achieving highly sensitive detection of miRNA-21 content and obtaining a low detection limit of 0.65 fM. The high specificity of the ECL biosensor was also proved by base mismatch. SignificanceCompared with other current detection methods, this sensor can achieve quantitative analysis of other target analytes by flexibly changing the probe DNA sequence, and provide a new feasible solution for the detection of tumor-associated markers. Benefiting from the improved sensitivity and selectivity, the proposed biosensing platform is expected to provide a new strategy for biomarkers analysis and outstanding prospect for further clinical application.

Ultrasensitive Electrochemiluminescence Biosensor Based on DNA-Bio-Bar-Code and Hybridization Chain Reaction Dual Signal Amplification for Exosomes Detection.

Exosomes have received considerable attention as potent reference markers for the diagnosis of various neoplasms due to their close and direct relationship with the proliferation, adhesion, and migration of tumor. The ultrasensitive detection of cancer-derived low-abundance exosomes is imperative, but still a great challenge. Herein, we report an electrochemiluminescence (ECL) biosensor based on the DNA-bio-bar-code and hybridization chain reaction (HCR)-mediated dual signal amplification for the ultrasensitive detection of cancer-derived exosomes. In this system, two types of aptamers were modified on the magnetic nanoprobe (MNPs) and gold nanoparticles (AuNPs) with numerous bio-bar-code DNA, respectively, which formed "sandwich" structures in the presence of specific target exosomes. The "sandwich" structures were separated under magnetic field, and the numerous bio-bar-code DNA were released by dissolving AuNPs. The released bio-bar-code DNA triggered the HCR procedure to produce a good deal of long DNA duplex structure for embedding in hemin, which generated strong ECL signal in the presence of coreactors for ultrasensitive detection of exosomes. Under the optimal conditions, it exhibited a good linearly of exosomes ranging from 10 to 104 exosomes particle μL-1 with limit of detection down to 5.01 exosome particle μL-1. Furthermore, the high ratio of ECL signal and minor change of ECL intensity indicated the good specificity, stability, and repeatability of this ECL biosensor. Given the good performance for exosome analysis, this ultrasensitive ECL biosensor has a promising application in the clinical diagnosis of early cancers.

Metal-Organic Framework-Derived High-Entropy Oxides as Coreaction Accelerators for an Efficient Luminol/Dissolved Oxygen Electrochemiluminescence System for Ultrasensitive Mercury Detection.

The development of luminol-dissolved O2 (luminol-DO) electrochemiluminescence (ECL) systems is crucial for real-world applications. Despite its stability and low biotoxicity, luminol-DO ECL systems struggle with low ECL performance due to their low reactivity. Investigating new materials like coreactant accelerators increases reactive oxygen species (ROS) formation and enhances luminol-DO ECL intensity. Motivated by the ROS-mediated ECL process, for the first time, we designed oxygen vacancy (OV)-rich high-entropy oxides (HEO) with five metal components [(FeCoNiCuZn)O] derived from metal-organic frameworks (MOFs) as coreaction accelerators to establish efficient luminol-DO ECL systems. High entropy (HE) MOFs were annealed at four different temperatures (600, 700, 800, and 900 °C). Indeed, the HE MOFs annealed at 800 °C (HEO-800) showed a 120-fold stronger ECL intensity compared to the bare glassy carbon electrode in the luminol-DO ECL system. The enhanced ECL performance can be attributed to the porous structure, unique morphology, heterostructures, high-density active sites, rich OV, unsaturated metals, and synergistic impact, which act as catalysts to accelerate the conversion of DO to ROS. The developed HEO-800-based luminol-DO ECL system can be effectively used for the high-sensitivity detection of mercury ions (Hg2+). The system detected Hg2+ over a wide concentration range from 0.1 nM to 100 μM, with a detection limit of 0.02 nM. The sensing mechanism relied on high-affinity metallophilic Hg2+-HEO-800 interactions, effectively quenching the ECL intensity of the luminol-DO/HEO-800 ECL system. The ECL sensing platform, developed without H2O2, offers a novel method for detecting substances, demonstrating significant potential for clinical diagnosis and biomarker analysis.

Nanochannel-confined platinum nanostructure for enhancement of luminol-dissolved oxygen electrochemiluminescence coupled with gated aptasensor for sensitive detection of carcinoembryonic antigen

Rapid and precise detection of tumor biomarkers in serum is of great significance for early diagnosis, treatment assessment, and recurrence monitoring of cancers. The fabrication of user-friendly electrochemiluminescence (ECL) aptasensors with effective signal amplification is highly desirable. In this study, an ECL aptasensor was developed with luminol-based ternary ECL platform using dissolved oxygen as endogenous co-reactant and nanochannel-confined platinum nanoparticles (PtNPs) as co-reactant promoter, which can realize highly sensitive detection of the tumor biomarker, carcinoembryonic antigen (CEA). On the cost-effective indium tin oxide (ITO) electrode, amino-modified vertically-ordered mesoporous silica film (NH2-VMSF) was easily grown to form high-density nanochannel array with ultrasmall nanochannels. PtNPs were then in-situ synthesized within the nanochannels via electrodeposition. Ternary ECL system was successfully fabricated as confined PtNPs can catalyze the electroreduction of dissolved oxygen at negative potentials as well as electrochemical oxidation of luminol, enhancing the ECL signal of luminol. The recognitive aptamer (Apt) was covalently immobilized on the outer surface of NH2-VMSF, resulting in the fabrication of an aptasensor. In presence of CEA, a decreased ECL signal was obtained as the formed complex on the recognition interface hindered the diffusion of ECL emitter to the supporting electrode. Based on this signal turn-off mode, sensitive detection of CEA was achieved ranged from 10 fg mL−1 to 100 ng mL−1, with a low detection limit (DL, 0.4 fg mL−1). The aptasensor displayed high selectivity and good reproducibility. The nanochannel-based aptasensor and ternary ECL system demonstrates great potential in convenient and sensitive detection of cancer biomarker.

Water oxidation coupled singlet oxygen electrochemiluminescence at C4N3 nanosheets/TiO2 nanotubes/Ti electrodes and its sensing application

Singlet oxygen (1O2) electrochemiluminescence (ECL) induced by water oxidation might intrigue new kinds of ECL-based sensors to be developed, but remains nascent due to its difficulty to be achieved. Herein, we report a water oxidation coupled ECL emission from dimeric aggregates of 1O2 at C4N3 nanosheets (NSs)/TiO2 nanotubes (NTs)/Ti electrodes (C4N3/TiO2/Ti) in the presence of triethanolamine (TEOA) as the co-reactant. The half-metallic C4N3 NSs were introduced to TiO2 NTs/Ti electrodes via in-situ thermal polymorization of ionic liquid precursor, which endows the TiO2 NTs with more oxygen vacancies and faster charge transfer ability as well as provides more sites for oxygen enriching, leading to an ECL intensity being 5.5 folds that at the TiO2 NTs/Ti electrodes. Besides, the tubelike shape of TiO2 makes it easier for the generated 1O2 to react each other to form dimeric aggregates, resulting in a typical ECL emission peak at ∼ 642 nm. Using the 1O2 ECL to detect dopamine (DA) as a model target, a wide linear range from 20 pM to 400 nM is obtained with detection limit of 7.6 pM (S/N = 3). This work offers a deep insight into water oxidation coupled 1O2 ECL and also accelerates its biosensing applications.

Near Infrared Aggregation Induced Electrogenerated Chemiluminescence Studies of Xanthene Dye

Electrogenerated chemiluminescence (ECL) serves as a versatile electrochemical-spectroscopic tool for rapid sample analysis, offering high sensitivity, good selectivity, and a low detection limit. During electrochemical redox reactions of luminophores and often ECL co-reactants, excited state luminophore species are formed through high energetic electron transfer between oxidized and reduced luminophore radicals or between the radical cation or anion and co-reactant intermediates. This process emits photons, generating ECL. Near infrared (NIR) luminophores represent an emerging class of materials in ECL studies. However, greater vibronic coupling between the ground and excited state in NIR luminophores with a lower band gap promotes nonradiative decay. The aggregation-induced emission (AIE) phenomenon overcomes these challenges, demonstrating enhanced radiative emission. We conducted a study on the photophysical, electrochemical, and ECL behavior of XanthCR-880 dye, which comprises a thienylpiperidine donor and a xanthene core as an acceptor. The central xanthene core provides extended conjugated length and increased charge transfer, resulting in NIR absorption at 880 nm and fluorescence emission at 960 nm, with a stroke shift of 80 nm. Cyclic voltammetry performed at a Pt electrode in MeCN with a scan rate of 50 mVs-1 revealed two oxidation waves and two reduction waves at 0.35 V, 0.70 V, -0.70 V, and -1.55 V vs Ag/Ag+, respectively. Due to the limited potential window of the Pt electrode in MeCN (not exceeding -2.5 V, a boron-doped diamond (BDD) electrode was employed at more negative potentials, uncovering an additional reduction wave at -2.62 V vs Ag/Ag+. The cathodic and anodic ECL behavior of XanthCR-880 dye was investigated using benzoyl peroxide and 2-(dibutylamino)ethanol as cathodic and anodic co-reactants, respectively. For cathodic ECL, XanthCR-880 dye produced two ECL waves at the BDD electrode, with peak potentials of -2.06 V and -2.36 V, respectively. In anodic ECL, relatively weak emission was observed at 1.05 V. ECL spectra were generated using the cathodic ECL pathway and interference filters as wavelength selectors, revealing a maximum emission at ~975 nm. The proposed ECL mechanism, as well as AIE studies, will also be discussed.

(Invited) Multiplexed CRISPR-Based ECL Assay for Alzheimer’s Biomarkers

Currently, more than 6 million Americans live with Alzheimer’s disease (AD), and it is projected to be 13 million by 2050. AD has no permanent cure yet, and early detection is important to slow down the progress of the disease. Diagnosis is complicated by AD’s similarity to other geriatric diseases. Beta-amyloid peptide (Aβ42), tau proteins and neurofilament light (NFL) measured in the cerebrospinal fluid (CSF) is a reasonably effective method for diagnostics, but very painful for the patients. MicroRNA’s (miRNAs) expressed in the brain are promising biomarkers and our goal of this study is to develop a sensitive and selective point-of-care (POC) test to detect AD specific miRNA (miRNA 30e, 34c and 200c) based on the CRISPR-Cas system. The Cas 13a protein has the regular sequence specific RNase activity followed by a collateral RNase activity. We used this feature of Cas 13a to generate an electrochemiluminescence (ECL) signal by binding specific miRNA biomarkers, and then collaterally cleaving poly-ribose guanine (poly-rG). This cleaved strands of poly-rG and rG itself are coreactants for ECL, and react with ECL polymer Ruthenium Polyvinyl Pyridine (RuPVP) to generate ECL. RuPVP is deposited into pyrolytic graphite (PG) micro wells. Using a 3D-printed microfluidic device equipped with the Pt reference and Ag/AgCl counter electrodes, patient serum mixed with poly-rG is introduced to the RuPVP coated electrode at 1.3 V to provide ECL light measured by a CCD camera. The assay was multiplexed to detect 3 AD specific miRNAs, and obtain a separate calibration for each miRNA biomarker with linear ranges from 70 pg/ mL to 7 µg/mL, from 7.4 pg/ mL to 74 µg/ mL and from 7.4 fg/ mL to 74 µg/ mL for 30e, 34c and 200c respectively. Preliminary LODs were 42 pg/ mL, 0.074 fg/ mL and 0.15 fg/ mL for miRNA 30e, 34c and 200c respectively. Results confirm the sensitivity of the assay. Further, spike recovery, cross reactivity studies and patient sample assays will be reported.

Electrochemiluminescence in “Planar” Micropore for Application in Single Cell Cytokine Biosensing

The immune response is a complex process involving interactions mediated by cellular secretions (cytokines). These key proteins dictate each cell’s behavior and are thus important markers to decipher the immune response. Produced in very low quantities, at the single cell level, their efficient detection is still a bottleneck for the complete understanding of the immune process.Since the early 2000s, biosensors based on micro and nanopores have emerged for the detection and identification of biomolecules [1]. However, the main challenge of such biosensors remains the appropriate functionalization of pores for selectivity. Previsouly, we developed a contactless electrofunctionalization technique (CLEF) for the localized functionalization of the inner walls of a pore, drilled in a silicon membrane covered with SiO2 [2]. The main advantage of this technique is that it only functionalizes the pore and not the surrounding membrane. The functionalization mechanism is inspired by bipolar electrochemistry (BPE) where a voltage is applied between two electrodes positioned at each side of the pore, allowing electrochemical reactions exclusively at the restriction site, which is polarized under the applied voltage.More recently, we have adapted CLEF to « planar » micropores i.e. restrictions in microfluidic channels, which are easier to integrate into microfluidic devices. We have successfully performed, inside of a silicon planar micropore, i) the bipolar electropolymerization of pyrrole [3] and ii) the bipolar electrochemiluminescence (ECL) [4,5], in a locally controlled manner. In this work, we aim to combine bipolar functionalization and bipolar ECL to conceive relevant biosensors for cytokine detection. To take into account the ECL requirements, polymers with higher over oxidation potential are selected. To achieve efficient localized BPE on Si, dedicate microfluidic design with two different canal thicknesses were developed and tested.As a proof of concept, we illustrate reproducible analytes detection by ECL on silicon inside of a microfluidic device. The specific biorecognition of these analytes is achieved via aptamer and antibody recognition.Two different strategies of functionalization were evaluated in terms of stability of the ECL behavior: 1) direct copolymerization of thiophene derivatives on bare Si and 2) copolymerization on electrodeposited Au. Moreover, since our final goal is to achieve detection of single cell secretions, the microfluidic setup was also simulated using a multiphysics simulation to ensure the device’s capability to trap and isolate single cells.This platform should allow further development of devices for the detection of various cytokines at the single cell level.Ref :[1] M. Tsutsui, et al., Sci. Rep. 2017, 17371[2] A. Bouchet et al. 2009 Small, 5: 2297-2303.[3] Abdulghani Ismail et al. Adv.Mater. Technol.2021, 6, 2001154[4] Silvia Voci et al. 2020 J. Electrochem. Soc. 167 137509[5] Abdulghani Ismail et al., Analytical Chemistry 2019 91 (14), 8900-8907 Figure 1

Zr-MOF Carrier-Enhanced Dual-Mode Biosensing Platforms for Rapid and Sensitive Diagnosis of Mpox.

Dual-mode readout platforms with colorimetric and electrochemiluminescence (ECL) signal enhancement are proposed for the ultrasensitive and flexible detection of the monkeypox virus (MPXV) in different scenes. A new nanotag, Ru@U6-Ru/Pt NPs is constructed for dual-mode platforms by integrating double-layered ECL luminophores and the nanozyme using Zr-MOF (UiO-66-NH2) as the carrier, which not only generates enhanced ECL and colorimetric signals but also provide greater stability than that of commonly used nanotags. Dual-mode platforms are used within 15min from the "sample in" to the "result out" steps, without nucleic acid amplification. The colorimetric mode allows the screening of MPXV with the visual limit of detection (vLOD) of 0.1 pM (6 × 108 copies µL-1) and the ECL mode supports quantitative detection of MPXV with an LOD as low as 10 aM (6 copies·µL-1), resulting in a broad sensing range of 60 to 3 × 1011 copies·µL-1 (10 orders of magnitude). Validation is conducted using 50 clinical samples, which is 100% concordant to those of quantitative polymerase chain reaction (qPCR), indicating that Ru@U6-Ru/Pt NPs-based dual-mode sensing platforms showed great promise as rapid, sensitive, and accurate tools for diagnosis of the nucleic acid of MPXV and other infectious pathogens.

Electron-Accelerator-Induced Fast Electron Transfer for Enhancing Electrochemiluminescence of Gold Nanoclusters and Its Bioanalysis Application: A Novel Avenue for Developing High-Efficient Emitters.

Herein, the gold nanoclusters/CaFe2O4 nanospheres (Au NCs/CaFe2O4) heterostructure as a novel electrochemiluminescence (ECL) emitter was developed. Excitingly, Au NCs/CaFe2O4 displayed highly efficient and greatly stable ECL based on the newly defined electron-accelerator p-type semiconductor CaFe2O4 NS-induced fast electron transfer; it solved one key obstacle of metal NC-based ECL emitters: sluggish through-covalent bond electron transport kinetics-caused inferior ECL performance. Specifically, on account of the energy level matching between emitter Au NCs and electron-accelerator CaFe2O4 NSs, the valence band (VB) of the electron-accelerator could provide abundant holes for rapidly transporting the electrogenerated electron from the highest occupied molecular orbital (HOMO) of Au NCs to the electrode, generating massive excited species of Au NCs for strong ECL emission. Notably, Au NCs/CaFe2O4 emerged 5.4-fold higher ECL efficiency with 3.5-fold higher electrochemical oxidation current in comparison with pure Au NCs, exhibiting great prospects in extensive lighting installations, ultrasensitive biosensing, and high-resolution ECL imagery. As applications, an ECL bioassay platform was constructed with Au NCs/CaFe2O4 as an emitter and U-like structure-fueled catalytic hairpin assembly (U-CHA) as a signal amplifier for fast and trace analysis of aflatoxin B1 (AFB1) with the detection limit (LOD) down to 2.45 fg/mL, which was 3 orders of magnitude higher than that of the previous ECL biosensors with much better stability. This study developed an entirely new avenue for enlarging the ECL performance of metal NCs, and it is a very attractive orientation for directing the reasonable design of prominent metal NC-based ECL emitters and broadening the practical application of metal NCs.

High-Sensitivity Homogeneous Detection of miRNA-155 Governed by DNA Walker-Regulated Surface DNA Density of Magnetic Electrochemiluminescence Nanoparticles.

Homogeneous electrochemiluminescence (ECL) has gained attention for its simplicity and stability. However, false positives due to solution background interference pose a challenge. To address this, magnetic ECL nanoparticles (Fe3O4@Ru@SiO2 NPs) were synthesized, offering easy modification, magnetic separation, and stable luminescence. These were utilized in an ECL sensor for miRNA-155 (miR-155) detection, with locked DNAzyme and substrate chain (mDNA) modified on their surface. The poor conductivity of long-chain DNA significantly impacts the conductivity and electron transfer capability of Fe3O4@Ru@SiO2 NPs, resulting in weaker ECL signals. Upon target presence, unlocked DNAzyme catalyzes mDNA cleavage, leading to shortened DNA chains and reduced density. In contrast, the presence of short-chain DNA has minimal impact on the conductivity and electron transfer capability of Fe3O4@Ru@SiO2 NPs. Simultaneously, the material surface's electronegativity decreases, weakening the electrostatic repulsion with the negatively charged electrode, resulting in the system detecting stronger ECL signals. This sensor enables homogeneous ECL detection while mitigating solution background interference through magnetic separation. Within a range of 100 fM to 10 nM, the sensor exhibits a linear relationship between ECL intensity and target concentration, with a 26.91 fM detection limit. It demonstrates high accuracy in clinical sample detection, holding significant potential for clinical diagnostics. Future integration with innovative detection strategies may further enhance sensitivity and specificity in biosensing applications.

Potential-Resolved Ratio Electrochemiluminescence Biosensor Based on Perylene Diimide-MOF and DNA Nanoflowers-CdS Quantum Dots for Detection of Dual Targets.

BRCA1 gene and carcinoembryonic antigen (CEA) are important markers of breast cancer, so accurate detection of them is significant for early detection and diagnosis of breast cancer. In this study, a potential-resolved ratio electrochemiluminescence (ECL) biosensor using perylene diimide (PDI)-metal-organic framework and DNA nanoflowers (NFs)-CdS quantum dots (QDs) was constructed for detection of BRCA1 and CEA. Specifically, PDI-MOF and CdS QDs can generate potential-resolved intense ECL signals only using one coreactant, so the detection procedure can be effectively simplified. PDI-MOF was first attached to the electrode by graphene oxide, and the dopamine (DA) probe was linked to quench the ECL signal by DNA hybridization. In the presence of target BRCA1, it can form a bipedal DNA walker, so the quenching molecules (DA) were detached from the electrode via the walker amplification process aided by Mg2+, so that the PDI signal at -0.25 V was restored for the BRCA1 assay. Moreover, CdS QDs@DNA NFs as amplified signal probes were formed by self-assembly, and the target CEA-amplified product introduced the CdS QDs@DNA NFs to the electrode, so the QD ECL signal at -1.42 V was enhanced, while the ECL signal of PDI is unchanged; thus, CEA detection was achieved by the ratio value between them. Therefore, the detection accuracy is guaranteed by detection of two cancer markers and a ratio value. This biosensor has a great contribution to the development of new ECL materials and a novel ECL technique for fast and efficient multitarget assays, showing great significance for the early monitoring and diagnosis of breast cancer.

High-Efficient Electrochemiluminescence of DNA-Au Ag Nanoclusters with Au NPs@Ti3C2 as a Novel Coreaction Accelerator for Ultrasensitive Biosensing.

In this work, an ultrasensitive electrochemiluminescence (ECL) biosensor was constructed based on DNA-stabilized Au Ag nanoclusters (DNA-Au Ag NCs) as the efficient luminophore and Au NPs@Ti3C2 as a new coreaction accelerator for determining microRNA-221 (miRNA-221) related to liver cancer. Impressively, DNA-Au Ag NCs were stabilized by the high affinity of the periodic 3C sequence, exhibiting an excellent ECL efficiency of 27% compared with classical BSA-Au Ag NCs (16%). Moreover, the Au NPs@Ti3C2 nanocomposites, as a new coreaction accelerator, were first introduced to accelerate the production of abundant sulfate free radicals (SO4•-) for promoting the ECL efficiency of DNA-Au Ag NCs in the DNA-Au Ag NCs/Au NPs@Ti3C2/S2O82- ternary system due to the energy band of Au NPs@Ti3C2 being well-matched with the frontier orbital of S2O82-. Furthermore, the trace target (miRNA-221) could drive the rolling circle amplification to generate an amount of output DNA with periodic 3C and 10A sequences. Through covalent bonds on the surface of poly A and Au NPs, the distance between the luminophor and the coreaction accelerator could be narrowed to further enhance the detection sensitivity. As a result, the constructed sensor has been applied for the ultrasensitive detection of miRNA-221 with a low detection limit of 50 aM and successfully monitored miRNA-221 in MHCC-97L and HeLa cell lysates. This strategy could be utilized for guiding the synthesis of light-emitting DNA-metal NCs, which has great potential in the construction of ultrasensitive biosensors for the early diagnosis of diseases.

Dynamic Monitoring of Time-Dependent Evolution of Biomolecules Using Quantum Dots-Based Biosensors Assemblies.

The dynamic monitoring of biomolecules that are part of cell membranes generally constitutes a challenge. Electrochemiluminescence (ECL) biosensor assemblies provide clear advantages concerning microscopic imaging. Therefore, this paper proposes and analyzes a quantum dots-based biosensor assembly. Thus, particular attention is granted to biomolecules that are part of cell membranes. Additionally, this paper describes and analyzes a quantum dots-based biosensor assembly, which is used to implement a fully functional color ECL visualization system that allows for cellular and biomolecular structures to be accurately visualized. The related nano-emitter allows the implementation of real-time bioimaging scenarios. Consequently, the proposed approach is thoroughly evaluated relative to the time-dependent evolution of biomolecules. It has been demonstrated that traditionally problematic structures, like the biomolecules that are part of cell membranes, can be studied and monitored relative to their time-dependent dynamic evolution using the proposed solution. The reported research process has been conducted in the realm of cooperation with a specialized biomedical engineering company, and the described results are expected to substantially support a better understanding of the biomolecules' time-dependent dynamic evolution.

Solid electrochemiluminescence sensor by immobilization luminol in Zn-Co-ZIF CNFs for sensitive detection of procymidone in vegetables.

Asolid-state electrochemiluminescence (ECL) sensor was fabricated by immobilizing luminol, a classical luminescent reagent, on a Zn-Co-ZIF carbon fiber-modified electrode for the rapid and sensitive detection of procymidone (PCM) in vegetable samples. The sensor was created by sequentially modifying the glassy carbon electrode with Zn-Co-ZIF carbon fiber (Zn-Co-ZIF CNFs), Pt@Au NPs, and luminol. Zn-Co-ZIF CNFs, prepared through electrospinning and high-temperature pyrolysis, possessed a large specific surface area and porosity, making it suitable as carrier and electron transfer accelerator in the system. Pt@Au NPs demonstrated excellent catalytic activity, effectively enhancing the generation of active substances. The ECL signal was significantly amplified by the combination of Zn-Co-ZIF CNFs and Pt@Au NPs, which can subsequently be diminished by procymidone. The ECL intensity decreased proportionally with the addition of procymidone, displaying a linear relationship within the concentration range 1.0 × 10-13 to 1.0 × 10-6 mol L-1 (R2 = 0.993). The sensor exhibited a detection limit of 3.3 × 10-14 mol L-1 (S/N = 3) and demonstrated outstanding reproducibility and stability, making it well-suited for the detection of procymidone in vegetable samples.