Electrochemiluminescence Emission Research Articles

2D Flower-like CdS@Co/Mo-MOF as Co-Reaction Accelerator of g-C3N4-Based Electrochemiluminescence Sensor for Chlorpromazine Hydrochloride

In this study, we have proposed an electrochemiluminescence (ECL) signal amplification system which is based on two-dimensional (2D) flower-like CdS@Co/Mo-MOF composites as a co-reaction accelerator of the g-C3N4/S2O82− system for ultrasensitive detection of chlorpromazine hydrochloride (CPH). Specifically, the 2D flower-like Co/Mo-MOF with mesoporous alleviated the aggregation of CdS NPs while simultaneously fostering reactant-active site contact and improving the reactant–product transport rate. This allowed the material to act as a novel co-reaction accelerator, speeding up the transformation of the S2O82− into SO4•− and enhancing the cathodic ECL emission of g-C3N4. Moreover, the signal probe which was synthesized by coupling the 2D CdS@Co/Mo-MOF and graphitic carbon nitride (g-C3N4) achieved the generation of SO4•− in situ and reduced energy loss. The results confirmed that the ECL signal was enhanced 6.2-fold and stabilized by CdS@Co/Mo-MOF. Based on the extremely strong quenching effect of chlorpromazine hydrochloride (CPH) on this system, a “signal-off” type sensor was constructed. The sensor demonstrated excellent sensitivity and linear response to CPH concentrations ranging from 1 pmol L−1 to 100 μmol L−1, with a low detection limit of 0.4 pmol L−1 (S/N = 3).

Alkynyl Ligands Templated Assemblies of Silver Nanoclusters with Exceptional Electrochemiluminescence Activity for Pancreatic Cancer Specific tsRNAs Measurement.

Proper manipulation of the ligand complex on the motifs of metal nanoclusters (MNCs) to form an ordered self-assembly is an effective approach to enhance the electrochemiluminescence (ECL) emission of MNCs. We report a facile approach for the preparation of self-assembled AgNCs (AgNCsAssy) induced by alkynyl ligands with enhanced ECL and stability. The formation of these AgNCsAssy was simultaneously driven by the diverse coordination modes of alkynyl ligands with Ag and intercluster interactions, for which it was found that the para-substituted alkynyl ligands exhibited apparently irregular nanoparticles, while the monosubstituted counterparts were present in the form of ribbons. The calculations revealed that the energy gap between the highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs) played a crucial role in their ECL emissions because of the substituent effects, especially, the low-lying LUMO levels could help to enhance the ECL emission. Moreover, mechanistic studies revealed that both the coreactant and alkynyl ligands made significant contributions to the ECL performance. Concurrently, the CRISPR-associated proteins (CRISPR-Cas) 12a system shows great potential in biosensing applications due to the advantages of easy design and precise targeting. As a proof of concept, we integrated the cascade amplification of catalytic hairpin assembly (CHA) circuit and the collateral cleavage activity of CRISPR-Cas12a to construct an ultrasensitive ECL biosensor for pancreatic cancer (PC)-specific tsRNAs, with a detection limit of 3.33 fM. This work is not only instructive for the synthesis of self-assembled MNCs with high ECL activities but also contributes to the understanding of the ECL mechanism of self-assembled MNCs.

Ultrasensitive electrochemiluminescencent multivalent aptamer sensor based on energy and electron transfer dual quenching tactics.

Anefficient "on-off-on" electrochemiluminescence (ECL) aptasensor utilizing dual-mechanism quenching was constructed for detecting furanyl fentanyl (FuF). The first signal "on" state was achieved by novel dual-ligand zinc metal-organic frameworks (Zn-MOFs), which were synthesized by self-assembly reaction using zinc atom clusters as metal nodes, achieving strong and stable ECL emission. The "off" state was realized by the energy and electron quenching effect of copper-doped WO3. Specifically, in addition to the overlap of the UV-Vis spectrum, energy transfer existed between the acceptor and donor after doping copper. Therefore, copper created a "highway" for electron transfer between the donor and acceptor, which greatly improved the quenching efficiency. Simultaneously, employing multivalent aptamers as capture probes augmented the binding affinity and probability of association between aptamer and target through a synergistic multivalent effect. Consequently, the second "on" state was the ECL signal restored by introducing FuF. Benefiting from the combination of the multivalent aptamers strategy with the "on-off-on" design, the developed aptasensor showed excellent linearity (1.0 × 10-13 to 1.0 × 10-6 g/L) with a low limit of detection of 5.5 × 10-14 g/L (S/N = 3). Additionally, it demonstrates a relative standard deviation (RSD) of less than 5% and good recovery ranging from 97.6 to 102%. The proposed aptasensor presents considerable potential for rapid, sensitive, and accurate determinationof FuF.

Efficient Charge Transfer Driven Electrochemiluminescence in Heteroatom-Involved Cocrystal Engineering for Detection of Uranyl Ions.

Embracing strategies that circumvent the complexities and disordered structures of electrochemiluminescence (ECL) emitters to improve charge transfer efficiency is crucial for advancing ECL technology to the forefront. Here, heteroatom-involved cocrystal engineering was introduced, constructing an ECL system with controllability of the charge transfer process. Through the mutual recognition and coassembly between functional monomers, highly ordered cocrystal superstructures are formed. The layered donor-acceptor arrays in cocrystals accelerated charge transfer, producing a remarkable ECL performance. Furthermore, distinct heteroatoms possess the capability to modulate the charge distribution of monomers by either pushing or pulling electrons. This modulation ultimately affects the charge transfer pathways within cocrystals, enabling ECL emissions of varying intensities and wavelengths. Notably, the presence of UO22+ would significantly inhibit the charge transfer in cocrystals, causing a quenching of ECL signal. This unique characteristic enables precise and selective detection of UO22+. The heteroatom-involved cocrystals hold immense potential to construct next-generation ECL emitters and create fresh opportunities for the advancement of ECL technology.

Rapid Preparation of a Self-Luminous Cd-Based Metal-Organic Framework Using AIEgen Ligands for High-Performance Electrochemiluminescence.

The design and synthesis of high-efficiency electrochemiluminescence (ECL) emitters hold great promise for a wide range of analytical applications. In this study, we developed a rapid and straightforward strategy to fabricate a self-luminous Cd-based metal-organic framework (Cd-MOF) using individual aggregation-induced emission ligands, specifically 1,1,2,2-tetrakis(4-(pyridin-4-yl)phenyl)ethane (TPPE), within a few seconds. The rigid and directionally enriched metal node of Cd, along with the organic ligands, is formed within the Cd-MOF via coordination, effectively constraining the intramolecular free motions of TPPE and suppressing nonradiative relaxation. Additionally, the unique porous structure combined with the catalytic activity resulting from the incorporation of Cd2+, endow the Cd-MOF with 90-fold ECL enhancement compared to individual TPPE as more chromophores are electro-excited and more coreactants are catalyzed to produce luminescence. The as-made Cd-MOF amplifies the ECL performance by integrating ECL emitters and coreactant accelerators into a single entity, simplifying the sensing process. Leveraging the excellent ECL performance, we constructed a sensitive ECL sensor for hydroquinone based on competitive reactions, with a wide linear range from 200 nM to 1 mM and a satisfying detection limit as low as 80 nM.

Photoinduced Electrochemiluminescence Immunoassays.

Optimization of electrochemiluminescence (ECL) immunoassays is highly beneficial for enhancing clinical diagnostics. A major challenge is the improvement of the operation conditions required for the bead-based immunoassays using the typical [Ru(bpy)3]2+/tri-n-propylamine (TPrA) system. In this study, we report a heterogeneous immunoassay based on near-infrared photoinduced ECL, which facilitates the imaging and quantitative analysis of [Ru(bpy)3]2+-modified immunobeads at low anodic potential. The photovoltage generated by the photoanode under near-infrared light promotes oxidation processes at the electrode/electrolyte interface, thus considerably lowering the onset potential for both TPrA oxidation and ECL emission. The anti-Stokes shift between the excitation light (invisible to the human eyes) and the visible emitted light results in a clear and stable signal from the immunobeads. In addition, it offers the possibility of site-selective photoexcitation of the ECL process. This approach not only meets the performance of traditional ECL immunoassays in accuracy but also offers the additional benefits of lower potential requirements and enhanced stability, providing a new perspective for the optimization of commercial immunoassays.

Annihilation Electrochemiluminescence Triggered by Bipolar Electrochemistry

AbstractBipolar electrochemistry (BE) combined with electrochemiluminescence (ECL) has gained considerable attention as a versatile and powerful analytical technique operating in a wireless manner. However, only co‐reactant ECL has been reported so far when using a BE setup. In this work, the generation of annihilation ECL at the anodic extremity of a bipolar electrode (BPE) is demonstrated in two different spatial arrangements of the electrodes. The reported approach is based on a synergetic effect between the asymmetric electroactivity induced across the BPE, which produces different redox states of [Ru(bpy)3]2+, and the electro‐migration mechanism of the formed ionic species, allowing the localization and concentration of the ECL emission. The presented approach demonstrating annihilation ECL via BE, paves the way for the design of easy and straightforward light‐emitting platforms for multiple applications.

In situ growth of L012-reduced gold nanoparticles-loaded graphitic carbon nitride nanocomposite for potential-resolved ratiometric electrochemiluminescence analysis

BackgroundMost electrochemiluminescence (ECL) analytical methods involve only changes in one single signal, which greatly limits their high sensitivity and stability for applied research. Potential-resolved electrochemiluminescence (PRECL), which provides calibrated analysis by self-correcting signal responses from dual channels, has attracted great interest in recent years. However, research on PRECL nanomaterials is still at an early stage. It is critical to develop a novel PRECL nanocomposite with high intensity in light emission, high resolution in potential separation, and reduced complexity in reaction systems for accurate detection. ResultsHere, a novel PRECL nanocomposite, L012-Au/g-C3N4, was synthesized by in situ growth of L012-reduced gold nanoparticles (L012-Au) on the surface of graphitic carbon nitride (g-C3N4) nanosheets. The g-C3N4 nanosheets served as effective carriers for L012 molecules and L012-Au, as well as efficient cathodic ECL emitters. With the addition of a single co-reactant (K2S2O8), two fully separated ECL peaks were observed around −1.3 V (ECL-1) and +0.6 V (ECL-2) at neutral conditions. The catalytic character of the incorporated gold nanoparticles accelerated the anodic ECL reaction and greatly enhanced the ECL intensity. Furthermore, an ECL mechanism based on the competitive relationship between K2S2O8 and dissolved oxygen was proposed. When dopamine (DA) was introduced into the PRECL reaction system, ECL-1 remained essentially unchanged, while ECL-2 intensity was significantly reduced. By analyzing the intensity ratio of ECL-2 to ECL-1 (I2/I1) to the detecting target, a ratiometric DA sensor with high sensitivity and stability was successfully constructed. SignificanceA nanocomposite L012-Au/g-C3N4 that can induce high-intensity ECL with two separated potentials in each polarity has been prepared by a simple synthetic method. The developed ratiometric sensor can eliminate systematic errors and improve accuracy. In addition, the multifunctionality of the nanocomposite and the necessity of only one co-reactant for neutral-condition ECL greatly reduced the reaction complexity. Our work offers new PRECL solutions to design highly sensitive and stable multi-response detection systems for in vitro diagnostics.

Step Pulse-Mediated Low-Triggering Potential Electrochemiluminescence of Polyfluorene Nanoparticles for Bioassay.

When the electrochemiluminescence (ECL) reaction occurs at a triggering potential beyond ±1.0 V, the interference from the adverse oxidation-reduction reaction cannot be ignored. However, currently reported anode ECL usually occurs above +1.0 V. This study innovatively developed a convenient and simple step pulse (SP) method to modulate the low ECL triggering potential of poly [(9,9-dioctyl-fluorenyl-2,7-diacyl)-alt-co-(9-hexyl-3,6-carbazole)] (PFA) nanoparticles (NPs). Compared to cyclic voltammetry with a triggering potential exceeding +1.25 V for PFA NPs, SP scanning enabled PFA NPs to exhibit a strong and stable ECL emission with a triggering potential as low as +0.75 V and tripropylamine (TPrA) as a coreactant. PFA NPs coupled an efficient aptameric recognition-driven cascade nucleic acid amplification strategy to construct a sensitive biosensing platform for measuring phosphorylated Tau (p-Tau) protein as an Alzheimer's disease biomarker. p-Tau could release the secondary target (ST) chain through the aptameric recognition reaction with the aptamer, and the released ST could further trigger cascade catalytic hairpin assembly (CHA) and rolling circle amplification (RCA) at the PFA NP-modified electrode, producing a large number of long chains. The large amount of G-quadruplex/hemin formed by long chains and hemin will consume the ECL quencher H2O2 added in detection solution, thereby restoring the ECL signal and enabling the low potential quantitative analysis of p-Tau with a limit of detection of 4.15 fg/mL. SP technique provides a new way to reduce ECL triggering potential, and PFA NPs create a promising low-triggering potential ECL-sensing platform for bioanalysis.

Ultralow Potential Cathodic Electrochemiluminescence Aptasensor for Detection of Kanamycin Using Copper Nanoribbons as Coreaction Accelerator.

An ultralow cathodic potential electrochemiluminescence (ECL) aptasensor was designed, employing DNA nanoribbon template self-assembly copper nanoclusters (DNR-CuNCs) as a novel coreaction accelerator within the luminol-H2O2 system for the sensitive detection of kanamycin (KANA). Mechanistic investigations revealed that the DNR-CuNCs preferred to generate highly active hydroxyl radicals by facilitating the reduction of the coreactant H2O2 under neutral pH conditions, consequently enhancing cathodic luminescence. By the strong π-π stacking effect of KANA aptamer and graphene as a signal modulation switch, DNR-CuNCs were displaced from the electrode surface due to the affinity of KANA and its aptamer, resulting in the inhibition of the luminol-H2O2 system and a decrease in the ECL signal. Under optimal experiments, the aptasensor demonstrated exceptional sensitivity in detecting KANA within the concentration range from 1 × 10-2 to 5 × 105 pg/mL, with the detection limit as low as 0.18 fg/mL. This innovative strategy provided a novel approach to designing effective ECL emitters for monitoring food safety.

Solid-phase electrochemiluminescence immunosensing platform based on bipolar nanochannel array film for sensitive detection of carbohydrate antigen 125.

Development of simple solid-phase electrochemiluminescence (ECL) immunosensor with convenient fabrication for high-performance detection of tumor biomarkers is crucial. Herein, a solid-phase ECL immunoassay was constructed based on a bipolar silica nanochannel film (bp-SNA) modified electrode for highly sensitive detection of carbohydrate antigen 125 (CA 125). Inexpensive and readily available indium tin oxide (ITO) electrode was used as the supporting electrode for the growth of bp-SNA. bp-SNA consists of a bilayer SNA film with different functional groups and charge properties, including negatively charged inner layer SNA (n-SNA) and positively charged outer layer SNA (p-SNA). The nanochannels of bp-SNA were used for the immobilization of ECL emitter tris(bipyridine)ruthenium(II), while the outer surface was utilized for constructing the immunorecognition interface. Due to the dual electrostatic interaction composed of electrostatic attraction from n-SNA and electrostatic repulsion from p-SNA, ECL emitter could be stably confined within bp-SNA, providing stable and high ECL signals to the modified electrode. After amino groups on the outer surface of bp-SNA were derivatized with aldehyde groups, recognition antibodies could be covalently immobilized, and an immunosensor was obtained after blocking nonspecific sites. When CA 125 binds to the antibodies on the recognition interface, the formed complex reduces the diffusion of the co-reactant tripropylamine (TPrA) to the supporting electrode, decreasing the ECL signal. Based on this mechanism, the constructed immunosensor can achieve sensitive ECL detection of CA 125. The linear detection range is from 0.01 to 100U/mL, with a detection limit of 4.7mU/mL. CA 125 detection in serum is also achieved. The construction immunosensor has advantages including simple and convenient fabrication, high stability of the immobilized emitter, and high selectivity, making it suitable for CA 125 detection.

Dual quenching ECL strategy based on AgInZnS quantum dots and a new co-reaction promoter oxygen vacancy-modified P5AIn/TiO2 for sensitive CEA detection

A novel electrochemiluminescence (ECL) biosensor for the sensitive detection of carcinoembryonic antigen (CEA) was constructed, utilizing environmentally friendly AgInZnS quantum dots (AgInZnS QDs) and a new co-reaction promoter enriched with oxygen vacancies, namely titanium dioxide/poly(5-aminoindole) (Ov-TiO2/P5AIn). The composite of P5AIn and TiO2 significantly enhanced the reaction rate of AgInZnS QDs with tripropylamine (TPrA). In addition, the presence of oxygen vacancies significantly enhances the electron migration rate of the electrode material, leading to more efficient catalysis of TPrA+ generation and a significant enhancement of ECL signals. Furthermore, a dual-quenching sensing strategy was employed using cuprous oxide-triaminophenol (Cu2O@APF) as the quencher, enabling the biosensor to switch. Through dual quenching of the ECL emission from AgInZnS QDs by Cu2O and APF, the biosensor achieves an extremely low “off” state of the ECL signal. Furthermore, a signal amplification strategy driven by the synergistic action of exonuclease III (ExoIII) and restriction endonuclease (Nt.BbvCI) was designed for a dual-site DNA walker, achieving cyclic amplification of the target signal and ECL signal, thereby turning the signal “on” again. The above mechanism significantly improved the specificity and sensitivity of the biosensor for CEA detection. The prepared biosensor exhibits good stability, selectivity, and sensitivity. The linear range for CEA detection is 5 × 10−14 to 10−8 M, with a detection limit of 16 fM. Additionally, the biosensor demonstrates satisfactory analytical capability for CEA in real blood samples. This strategy provides a reliable new approach for the sensitive detection of CEA and other tumor markers.

Rapid Size Determination of Quasispherical Gold Nanoparticles by Electrocatalysis Efficiency-Regulated Electrochemiluminescence.

The size of gold nanoparticles (AuNPs) largely decides their properties and applications, making the rapid screening of AuNP size important. Despite the fact that AuNP-amplified electrochemiluminescence (ECL) is widely used in various ECL sensing applications, the mechanism of ECL enhancement remains elusive, especially the quantitative relationship between the enhanced ECL intensity and the size of AuNPs. In this work, taking quasispherical and citrate-stabilized AuNPs as model nanoparticles, we have reported that the ECL intensity of the S2O82--O2 system enhanced significantly with the increasing AuNP size. AuNPs acted as bielectrocatalysts for reducing the S2O82- and O2. The further study of enhancement mechanism demonstrates that AuNPs with increasing size facilitate the electron transfer and promote the generation of radicals required for the ECL emission, which produces more emitters-singlet oxygen. Meanwhile, the high surface density of citrate on small AuNPs suppresses the ECL signal by forming an electrostatic barrier. On the basis of the above phenomena, an ECL-based rapid AuNP size screening approach has been established. The accuracy of this platform is verified by the consistent results in comparison to transmission electron microscopy (TEM) measurements. This work not only provides deep insight into the correlation between the AuNP size and the ECL enhancement but also contributes an alternative to the TEM technique for the rapid AuNP size screening. Additionally, this study also extends the exploration of ECL-based structure analysis techniques toward nanomaterials through clarifying the structure-electrocatalytic activity correlation.

Stable Halide Perovskite CsPbBr3 Nanocrystals Assisted by Covalent-Organic Frameworks for Electrochemiluminescence Analysis in an Aqueous Medium.

Lead halide perovskites have garnered attention as promising electrochemiluminescence (ECL) emitters owing to their superior photophysical characteristics. However, their poor water stability severely restricts their application in aqueous media for ECL. In this study, inorganic perovskite CsPbBr3 was assembled in situ in the imine-linked covalent-organic framework (COF-LZU1) as a novel ECL emitter. The expansive surface area and robust hydrophobic architecture of COF-LZU1 not only improved the water stability of CsPbBr3 but also guaranteed its exceptional ECL performance. The novel composite nanoluminescent material was coated onto an indium tin oxide (ITO) electrode via spin-coating and calcination processes to serve as an electrochemiluminescence (ECL) platform. A sensor was developed by combining a DNA hydrogel target-induced release system with a platform using ascorbic acid (AA) as a coreactant and T-2 toxin as the target analyte model. This method achieved a detection limit as low as 3.56 fg·mL-1 and was successfully applied to the analysis of the T-2 toxin content in corn samples. This study offers a novel path for the advancement of perovskite-based ECL emitters and their utilization in aqueous environments within the ECL field.

Self-Enhanced Electrochemiluminesence of Dye-Doped Polymer Dots for Coreactant-Free Visualized Detection of Iodide Ions.

The monitoring of radioactive iodide levels is of great significance in environmental science and cancer radiotherapy. In this work, a high-throughput, radiation-resistant, and visualized electrochemiluminescence (ECL) strategy was developed for detection of iodide ions. Herein, the hydrophobic ruthenium derivative (Ru(bpy)3[B(C6F5)4]2) (bpy = bipyridyl) was doped in tertiary amine-coupled polymer dots (N-PFO Pdots) to synthesize self-enhanced Pdots (Ru@Pdots), which showed extremely high ECL intensity in absence of coreactant. Due to the efficient ECL resonance energy transfer between Ru(bpy)3[B(C6F5)4]2 and N-PFO, the Ru@Pdots exhibited 18 times higher ECL intensity compared with bare N-PFO Pdots. Besides, Ru@Pdots also showed 220-times higher ECL intensity compared with Ru(bpy)3[B(C6F5)4]2 doped coreactant-dependent Pdots (Ru@PFO Pdots). Using Ru@Pdots as ECL emitters, an ECL imaging array was designed for iodide ion detection, which exhibited a detection range of 0.8 nM-4 μM and a limit of detection of 0.1 nM. In this strategy, iodide ions were oxidized as iodide free radicals on the surface of the electrode, which could further consume the nitrogen radical of Ru@Pdots and effectively quench the ECL signal. This method also showed good specificity, radiation-resistant performance, and accuracy in actual seawater sample testing, which indicated its value in marine environmental monitoring, nuclear security, and cancer radiotherapy.

Electrochemiluminescence of Carbon Dots and Nitrogen-Doped Carbon Dots from a Microwave-Assisted Method

This research focuses on the use of carbon dots (CDs) and nitrogen-doped carbon dots (NCDs) synthesized using a microwave-assisted method as electrochemiluminescence (ECL) luminophores. CDs have been synthesized using citric acid, while various concentrations of nitrogen-doped CDs have been successfully obtained by varying the amount of urea from 1 to 3 g with citric acid to produce NCD1, NCD,2 and NCD3. The ECL mechanism of CDs and NCDs on screen-printed electrodes has been studied using cyclic voltammetry (CV). ECL emission from as-prepared CDs and NCDs was observed in PBS with potassium persulfate (K2S2O8) as a co-reactant. The addition of potassium chloride (KCl) as a supporting electrolyte displays fast electroreduction of CDs and K2S2O8 to expedite the generation of CDs and peroxydisulfate radicals that simultaneously increase ECL intensity. Furthermore, as the concentration of nitrogen-doped CDs increases, so does the intensity of the ECL. NCD3 shows the highest ECL intensity by an increment of 86.4% in comparison to CDs in PBS with the addition of K2S2O8 and KCl. Finally, optimization of ECL measurement was carried out in terms of CV potential range, concentration of luminophore, supporting electrolyte, and co-reactant using NCD3 luminophore. The CV potential range at 0 to -2 V shows 50 mV of early CV reverse onset potential that resulted in an increase of 52.9% ECL intensity. Meanwhile, 30x dilution of NCD3, 0.1 M of supporting electrolyte KCl, and 0.1 M of co-reactant K2S2O8 show the optimum value to obtain high ECL intensity.

Sensitive detection of bisphenol A based on resonance energy transfer between zinc oxide nanoparticles enhanced luminol ECL and silver nanoparticles decorated TiVC MXene

This present work developed a highly sensitive electrochemiluminescence (ECL) sensor based on resonance energy transfer between ZnO nanoparticles (ZnONPs) enhanced luminol ECL as the energy donor and silver nanoparticle-modified TiVC MXene (AgNPs@TiVC) as the energy acceptor. ZnONPs were employed as catalysts to facilitate the reaction between luminol and dissolved oxygen, which could amplify the ECL signal of luminol without the need of additional co-reactants. The AgNPs@TiVC composite functioned as the energy acceptor, participating in ECL resonance energy transfer to quench the ECL emission. In the presence of bisphenol A (BPA), the specific recognition by the aptamer could detach the energy acceptor from the electrode surface, resulting in the recovery of ECL signal. The variation of ECL intensity exhibited a good linear relationship with the logarithm of BPA concentration in the range of 0.06 nM–0.08 μM, with a detection limit of 8.9 pM (3σ). This sensor owned satisfactory sensitivity and selectivity, which could further expand the utility of various MXenes in ECL sensing applications.

AIEgens-based luminescent metal-organic frameworks as novel electrochemiluminescence emitters Integrated with co-reaction amplification strategy for CA15-3 detection

A current research focus in the field of electrochemiluminescence (ECL) is the development of novel high-performance emitters. Herein, we reported the synthesis of a zirconium-based metal–organic framework (Zr-TBAPy-MOF) using the aggregation-induced emission luminogens (AIEgens) 1,3,6,8-tetra(4-carboxyphenyl)pyrene (H4TBAPy) as ligands and Zr6-clusters as nodes. The resulting AIE-active luminescent MOF (AIE-LMOF) exhibited superior ECL properties and was used as an ECL emitter to construct a high-sensitivity ECL immunosensor. Conceptual experiments demonstrated that Zr-TBAPy-MOF showed significantly stronger ECL emission compared to both the monomers and aggregates of H4TBAPy, attributed to the effective restriction of intramolecular motion (RIM). On the sensor substrate, we designed an Au@ZnO/Cu2O nanocomposite as a co-reactant accelerator. This significantly promoted the generation of sulfate radicals (SO4•−) from persulfate (S2O82−) through the sustainable switching of Cu+/Cu2+ oxidation states in copper oxide (Cu2O). Additionally, zinc oxide (ZnO), which had excellent electrochemical properties, further enhanced the catalytic activity of the materials. Leveraging these advantages, we developed a sandwich-type ECL immunosensor for the ultrasensitive detection of carbohydrate antigen 15–3 (CA15-3), demonstrating a wide sensitive range (0.001 − 100 U/mL) and a low detection limit (0.0007 U/mL). Overall, this work paves the way for the development of efficient ECL luminophores with significant potential in the field of immunoassays for the early diagnosis of disease.

Enhanced electrochemiluminescence of CdS QDs encapsulated in IRMOF-3 for sensitive detection of human epithelial protein 4

The advancement of pragmatic and highly-sensitive electrochemiluminescence (ECL) biosensors depends upon signal tags with high and stable signal intensity. Herein, enhanced ECL emission was obtained by encapsulating the dual-stabilizer-capped CdS QDs in a metal-organic framework (MOF), which served as a valid ECL signal tag for detecting biomarkers. Dual-stabilizer-capped CdS QDs reduce dangling bonds on the surface and improved the ECL emission. Furthermore, functionalized isoreticular metal-organic framework-3 (IRMOF-3) can not only load a large quantity of CdS QDs through the encapsulation capability but also serves as a co-reaction accelerator to promote the formation of more SO4•− from the S2O82−, further improving the ECL emission of QDs, while the integrated design of IRMOF-3 co-reaction accelerator and CdS QDs effectively shortens the electron transfer pathway and reduces the energy consumption in ECL system. Using human epithelial protein 4 (HE4) as the model of analysis, the biosensor demonstrated a broad linear range (50 fg mL−1∼50 ng mL−1) and a low detection limit (9.89 fg mL−1) under optimal operating conditions. The study provides an effective and alternative method to improve the ECL efficiency of QDs, significantly broadening their potential applications in sensing analysis, medical diagnostics, and bioimaging.

Novel Ternary System for Electrochemiluminescence Biosensor and Application toward Pb2+ Assay.

This study constructed an electrochemiluminescence (ECL) biosensor for ultrasensitive detection of Pb2+ in a ternary system by employing DNAzyme. The ternary system is composed of a potassium-neutralized perylene derivative (K4PTC) as the ECL emitter, K2S2O8 as the coreactant, and neodymium metal-organic frameworks (Nd-MOFs) as the coreaction accelerators. Nd-MOFs immobilize DNAzymes and enhance the luminescence intensity of the K4PTC/K2S2O8 system. As part of this system, K4PTC enhances the ECL signal in solution and supports Pb2+ detection. The sequence of ferrocene (Fc)-linked DNA (DNA-Fc) is catalytically cleaved by DNAzymes in the presence of Pb2+. This causes the removal of DNA1-Fc from the electrode surface to recover the ECL signal. As a result, the as-prepared ECL biosensor can quantify Pb2+ with a detection limit (LOD) of 4.1 fM in the range of 1 μM to 10 fM. The ECL biosensor displays high specificity, good stability, excellent reproducibility, and desirable practicality for Pb2+ detection in tap water. Moreover, by simply changing the sequence of the DNAzyme, new biosensors can be designed for ultrasensitive detection of different heavy metal ions, offering an excellent approach for monitoring water quality safety.