Coreaction Accelerator Research Articles

NiFe Nanoalloy Electrocatalyst as a Coreaction Accelerator for Enhancing Biomarker Electrochemiluminescence Imaging Detection.

The development of coreaction accelerators with excellent performance is crucial for improving electrochemiluminescence (ECL) performance. In this study, a NiFe nanoalloy electrocatalyst (NiFe-NAEC) was used as a coreaction accelerator to promote persulfate activation, resulting in a 44-fold increase in the ECL intensity of flower-like Zn-3,4,9,10-perylenetetracarboxylate (FL-Zn-PTC). Moreover, the synergistic combination of NiFe-NAEC and silver nanoparticles led to a 134-fold increase in the ECL intensity of FL-Zn-PTC, with a 6275% improvement in the ECL efficiency compared with a reference system containing Ru-bpy/K2S2O8. Consequently, a sensor was constructed for the visual detection of amino-terminal pro-brain natriuretic peptide. This sensor exhibited high sensitivity and provided intuitive results within a linear range from 0.01 to 1000 pg/mL, with a detection limit of 2.1 fg/mL. Overall, this study presents a strategy that integrates an electrocatalytic coreaction accelerator with synergistic enhancement to improve ECL performance. This approach has the potential to expand the range of emitter materials and advance ECL technology.

Integrating All-rounder TiO2 Accelerated Electrochemiluminescence with Dual-Quenching PDA@COF Probes for Sensitive Quantification and Protein Profiling of Tumorous Exosomes.

Exosomes have been perceived as promising biomarkers for noninvasive cancer diagnosis and treatment monitoring. However, the sensitive and accurate quantification and phenotyping of exosomes remains challenging. Herein, a versatile electrochemiluminescence (ECL) aptasensor was proposed for the sensitive analysis of tumorous exosomes. Specifically, a ternary nanohybrid (Ru-HAuTiO2), by covalently linking ECL luminophore Ru(dcbpy)32+ with gold nanoparticles (AuNPs)-decorated hollow urchin-like TiO2 (HTiO2), was ingeniously designed as a highly luminescent and self-enhanced ECL nanoemitter. Notably, the porous HTiO2 played an "all-rounder" role, including the carrier for ECL luminophores and AuNPs, coreaction accelerator, and specific exosome capturing scaffold through Ti-phosphate coordination interaction. On the other hand, a polydopamine modified covalent organic framework (PDA@COF) was employed as a quencher to remarkably attenuate the ECL of Ru-HAuTiO2 through a dual-quenching mechanism, and further labeled with a specific aptamer (Apt) of exosomal surface protein. Based on forming a Ru-HAuTiO2/exosome/Apt-PDA@COF sandwich structure on the electrode, a "signal on-off" ECL platform for tumorous exosomes was constructed, realizing sensitive detection within the range of 3.1 × 103 particles/mL to 1 × 108 particles/mL and a low limit of detection of 1.41 × 103 particles/mL, achieving phenotypic profiling of surface proteins on different tumorous exosomes. This work provides a promising alternative method for the detection and analysis of exosomes.

Multi-quenching electrochemiluminescence system based on resonance energy transfer from self-enhanced Ce(III, IV)-MOF@Ru to CuO@PDA@AuNPs for ultrasensitive detection of HER2

This study presents an innovative approach based on electrochemiluminescence resonance energy transfer (ECL-RET) through the introduction of a new pattern donor-acceptor couple. The donor of self-enhanced Ce(III, IV)-MOF@Ru is created by immobilizing Ru(bpy)32+ on Ce-based metal-organic frameworks (Ce(III, IV)-MOF). The acceptor of CuO@PDA@AuNPs is the CuO nanospheres polydopamine (PDA) framework grafted with gold nanoparticles (AuNPs). An ultrasensitive detection of human epidermal growth factor receptor-2 (HER2) was achieved through the development of a quenched ECL immunosensor. Ce(III, IV)-MOF, a unique 3D infinite extension framework, was recognized for its excellent nanostructure and remarkable capacity to greatly activate tripropylamine (TPrA) and generate abundant radicals. Fortunately, it was simultaneously utilized as a highly effective coreactant accelerator and encapsulation agent, thereby facilitating the immobilization of Ru(bpy)32+ and the generation of radicals for creating a self-enhanced emitter of Ce(III, IV)-MOF@Ru. Consequently, by effectively reducing the distance of electron transmission and minimizing the loss of energy, Ce(III, IV)-MOF@Ru achieved a significantly high efficiency in ECL. More importantly, CuO@PDA@AuNPs was prepared as a perfect quenching agent. The ultraviolet-visible (UV–vis) spectra of CuO@PDA@AuNPs exhibited partial overlap with ECL spectra of Ce(III, IV)-MOF@Ru, thus efficiently initiating the ECL-RET interaction between the donor and acceptor. With the purpose of demonstrating the superiority of newly obtained self-enhanced nanoemitter and donor-acceptor couple, an ECL immunoassay was proposed for the analysis of HER2 with range of 0.2 fg/mL ∼ 10 ng/mL and the limit of detection of 0.067 fg/mL. Therefore, this method supplies convenient and significant strategy for the clinical analysis.

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.

Ultrasensitive ECL immunoassay for CA15-3 via self-enhanced L012-loaded ZnNi-MOF as an emitter and CeO2–Pt as a co-reaction accelerator

Improvement in the sensitivity and accuracy of ECL-based biosensors, to a great extent, depends on the fabrication of high-performance electrochemiluminescence (ECL) sensors. Herein, polyethyleneimine (PEI)-grafted bimetallic ZnNi metal-organic framework (ZnNi-MOF/PEI) nanospheres were synthesized to prepare a L012-based ECL immunosensor for detecting carbohydrate antigen 15-3 (CA15-3). The introduced PEI was utilized not only as a bridging element for L012 luminophore and detection antibody (Ab2) immobilization but also as a co-reactant for generating the self-enhanced ZnNi-MOF/PEI-L012@Ab2 ECL signal probe. Furthermore, Pt nanoparticle-functionalized CeO2 nanorods (CeO2–Pt) featuring high-efficiency electrocatalytic properties, as a co-reaction accelerator, could catalyze H2O2 to generate abundant reactive oxygen species (ROS), further augmenting the ECL signal of ZnNi-MOF/PEI-L012@Ab2. In the presence of CA15-3 antigen, the capture antibody (Ab1)-conjugated CeO2–Pt complex (CeO2–Pt@Ab1) and ZnNi-MOF/PEI-L012@Ab2 would get closer to each other, with the formation of a “signal-on” sandwich-type ECL immunosensor. The ZnNi-MOF-assisted ECL biosensor achieved a detection limit of down to 5.75✕10−5 U mL−1. This work shows distinguished potential for measuring low levels of biomarkers that may help in the clinical diagnosis of breast cancer.

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.

A highly sensitive aptamer–antibody birecognized ECL sensing platform based on the cascaded reaction between CeO2@mrGO and Co-SAC@NC for E. coli O157:H7 in untreated milk

Rapid, sensitive and specific detection of foodborne pathogens is of great significance to the early warning and prevention of foodborne diseases and environmental pollution. Here, an electrochemiluminescent (ECL) biosensor with the cascaded reaction between two nanozymes was developed for the detection of E. coli O157:H7. Cobalt single-atom catalyst (Co-SAC@NC) with oxidase (OD) -like activity, as a co-reaction accelerator of O2, catalyzed oxygen to reactive oxygen species (ROSs) and boosted ECL of luminol-O2 system. Another nanozyme CeO2@mrGO with excellent phosphatase-like activity by the introduction of Fe was use to label Ab. CeO2@mrGO captured E. coli O157:H7, and then combined with Ap on the electrode surface through the affinity of aptamer and antibody to form a sandwich structure on the gold electrode (CeO2@mrGO-Ab/E. coli O157:H7/Ap-AuE). CeO2@mrGO converted AAP into AA, which consumed ROS and quenched ECL emission of luminol-O2 system. As a consequence, this ECL sensor had a linear response range of 17–1.7 × 105 CFU/mL with LOD of 2.78 CFU/mL. This aptamer-antibody birecognized system was able to be applied to assay E. coli O157:H7 in untreated contaminated milk samples with satisfactory results.

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.

A Smartphone-Mediated "All-In-One" Biosensing Chip for Visual and Value-Assisted Detection.

A smartphone-mediated self-powered biosensor is fabricated for miRNA-141 detection based on the CRISPR/Cas12a cross-cutting technique and a highly efficient nanozyme. As a novel nanozyme and a signal-amplified coreaction accelerator, the AuPtPd@GDY nanozyme exhibits an excellent ability to catalyze cascade color reactions and high conductivity to enhance the electrochemical signal for miRNA-141 assays. After CRISPR/Cas12a cross-cutting of S2-glucose oxidase (S2-GOD), the electrochemical signal is weakened, and miRNA-141 is detected by monitoring the decrease in the signal. On the other hand, a cascade reaction among glucose, H2O2, and TMB is catalyzed by GOD and AuPtPd@GDY, respectively, resulting in a color change of the solution, which senses miRNA-141. The self-powered biosensor enables value-assisted and visual detection of miRNA-141 with limits of detection of 3.1 and 15 aM, respectively. Based on the dual-modal self-powered sensing system, a smartphone-mediated "all-in-one" biosensing chip is designed to achieve the real-time and intelligent monitoring of miRNA-141. This work provides a new approach to design multifunctional biosensors to realize the visualization and portable detection of tumor biomarkers.

Ultrasensitive Electrochemiluminescence Biosensor with ZIF-67@MXene as an Efficient Co-Reaction Accelerator and Plasmonic Nanozyme as a Smart Signal Amplification Probe.

Exploring novel electrochemiluminescence (ECL) co-reaction accelerators to construct ultrasensitive sensing systems is a prominent focus for developing advanced ECL sensors. However, challenges still remain in finding highly efficient accelerators and understanding their promoting mechanisms. In this paper, ZIF-67@MXene nanosheet composites, with highly conductive in-plane structure and confined-stable pore/channel, are designed to act as high-efficient co-reaction accelerators and achieve a significant enhancement in the luminol-H2O2 based ECL system. Mechanism investigation suggests that hydroxyl radicals (·OH) and singlet oxygen (1O2) can be selectively and preferentially generated on ZIF-67@MXene due to the stable and efficient absorption of ·OH and 1O2, leading to a remarkable enhancement in the ECL efficiency of luminol (830%). Finally, by designing a plasmonic NH2-MIL-88@Pd nanozyme, an "on-off" switch immunosensor is constructed for the detection of prostate-specific antigen (PSA). Based on the multiple signal amplification effect, the linear detection range for PSA is expanded by three orders of magnitude. The detection limit is also improved from 1.44 × 10-11 to 9.1 × 10-13 g mL-1. This work proposes an effective method for the preparation of highly efficient co-reaction accelerators and provides a new strategy for the sensitive detection of cancer markers.

Fe, Cu dual-atom catalysts assisted molecularly imprinted electrochemiluminescence sensor for ultrasensitive detection of trichlorfon

Trichlorfon (TCF) has the possibility of contaminating agricultural crops and posing some health risks to humans. Herein, an electrochemiluminescence (ECL) sensor based on Fe, Cu dual-atom catalysts (Fe/Cu-N-C DACs) and Au@Luminol was developed for the ultrasensitive detection of TCF. Fe/Cu-N-C with diatomic sites has a very high catalytic activity and can be used as a co-reaction accelerator to activate H2O2 to generate a large number of hydroxyl radicals which triggered a strong cathodic ECL signal of luminol. TCF molecularly imprinted polymer (MIP) was further introduced as a specific recognition element, and the interaction between the template molecule and the functional monomer was verified by molecular docking technique. The developed sensing platform was successfully applied to the ultrasensitive detection of TCF with a linear range from 1.0 pg/mL to 5.0 μg/mL with a low detection limit (0.39 pg/mL). This study broadens the application of DACs in ECL sensing.

Tailoring a novel all-in-one host-guest solid-state electrochemiluminescence platform for selective detection of spermine using cucurbit-[6]-uril modified [Ru(bpy)3]2+ electrode

Herein, a novel solid-state electrochemiluminescence (ECL) based on electrochemically incorporated [Ru(bpy)3]2+ on nafion modified glassy carbon electrode ([Ru(bpy)3]2+-Nafion/GCE) followed by chemisorption of cucurbit-[6]-uril (CB-[6]) on Ru(bpy)3]2+-Nafion/GCE (as CB-[6]-[Ru(bpy)3]2+-Nafion/GCE) has been developed for selective sensing of spermine (SPM) which belongs to the class of aliphatic biogenic amines and overexpression of SPM is associated with several cancers, particularly “Prostate Cancer” (PCa). Interestingly, the ECL emission of [Ru(bpy)3]2+ be enhanced significantly in the presence of CB-[6] modified [Ru(bpy)3]2+-Nafion/GCE. This is due to inherent ability of CB- [6] act as a co-reactant accelerator. Upon the addition of SPM, the ECL emission was further enhanced due to electron transfer reaction between SPM and [Ru(bpy)3]3+. Selectivity of the proposed ECL sensor towards SPM arises from the host-guest interaction between the CB-[6] and SPM, follows the anodic co-reactant ECL reaction (oxidative reduction mechanism) by confirmation of electrochemical and spectroscopic results like electron spin resonance (EPR) and ECL spectra. The proposed solid-state ECL sensor platform is selectively detect to SPM for a linear range of 10 nM - 5 mM with detection limit (LoD) of 1.4 nM at physiological pH conditions. In addition, the developed ECL platform of CB-[6]-[Ru(bpy)3]2+-Nafion/GCE has been successfully verified to the sensing of SPM in the urine sample, proving the practicability of the proposed sensor is suitable for clinical analysis.

Aggregation-induced electrochemiluminescence of an indium-based metal–organic framework and resonance energy transfer strategy for the sensitive detection of β2-microglobulin

This study aimed to construct a novel aggregation-induced electrochemiluminescence (AIECL) system with an indium-based metal–organic framework (In-MOF) as a new luminophore and K2S2O8 as a co-reactant. In the constructed electrochemiluminescence (ECL) system, In-MOF served not only as a novel luminophore but also as a co-reaction accelerator. The In-MOF produced strong cathodic ECL emission over the wavelength range of 425–600 nm. The aggregation-caused quenching effect was overcome by altering the π-π stacking structure of 9,10-di(p-carboxyphenyl)anthracene (DPA) aggregates through coordination with metal ions. The In-MOF exhibited efficient ECL performance and better stability than the DPA ligand. Then, a novel quenched sensor based on the quenching effect of CeO2@PDA on the In-MOF ECL emission was fabricated for detecting β2-microglobulin (β2M). The immunosensor demonstrated an excellent linear relationship with a wide linear range (10 fg/mL – 200 ng/mL) and a low detection limit (2.9 fg/mL, S/N = 3) under optimized experimental conditions. The proposed biosensor had high sensitivity, reasonable specificity, high stability, and reproducibility, thus positively affecting the clinical application of sensing analysis.

Framework-Induced Electrochemiluminescence Enhancement of an AIEgen-Based MOF Coupled with Heterostructured TiO2@Ag NPs as an Efficient Coreaction Accelerator for Sensitive Biosensing.

In conventional metal-organic framework (MOF) luminophore-involved electrochemiluminescence (ECL) systems, the aggregation-caused quenching commonly exists for the organic luminescent ligands, limiting the ECL efficiency and detection sensitivity. Herein, by employing the aggregation-induced emission luminogen (AIEgen) 1,1,2,2-tetra(4-carboxylbiphenyl)ethylene (H4TCBPE) as a ligand, one high-efficiency ECL emitter (Zr-MOF) was synthesized through a simple hydrothermal reaction. Compared with H4TCBPE monomers and their aggregates, the resultant Zr-MOF possesses the strongest ECL emission, which is mainly attributed to the framework-induced ECL enhancement. Specifically, the heterostructure was prepared by the deposition of silver nanoparticles on TiO2 microflowers and utilized as an efficient coreaction accelerator. Remarkably, the formative heterojunction can increase the interfacial charge transfer efficiency and promote the carrier separation, facilitating the oxidation of coreactant tripropylamine. In this way, a novel aptamer-mediated ECL sensing platform is constructed, achieving the sensitive analysis of adenosine triphosphate with a low detection limit of 0.17 nM. As a proof-of-concept study, this work may enlighten the rational design of new-type MOF-based ECL materials and expand the application scope of the ECL technology.

A novel electrochemiluminescence aptasensor for ultrasensitive lincomycin detection using Ti3C2–TiO2–Ru probe

The presence of lincomycin (LIN) residues in food poses significant health risks to humans, necessitating a highly sensitive and specific detection method for LIN. This study used a self-enhancing Ti3C2–TiO2–Ru probe to develop an electrochemiluminescence aptasensor to detect LIN. The Ti3C2–TiO2 was synthesized in situ by harnessing the unique reducibility of Ti3C2, with TiO2 serving as a co-reaction accelerator. Moreover, Ti3C2–TiO2 served as a carrier with an excellent negative charge, allowing for the immobilization of a substantial amount of Ru(bpy)32+ through electrostatic adsorption, thus forming a self-enhancing Ti3C2–TiO2–Ru probe. Furthermore, the specific affinity of LIN toward the aptamer and the chelating interaction between the Ti and phosphate groups ensured highly precise LIN detection. This sensor demonstrated excellent performance, with a detection limit of 0.025 ng mL−1 and a detection range of 1.0 × 10−1–1.0 × 104 ng mL−1. The LIN detection in milk showed commendable recovery rates, ranging from 94.4% to 106.0%.

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.

Point-of-care testing device platform for the determinationof creatinine on an enzyme@CS/PB/MXene@AuNP-based screen-printed carbon electrode.

Screen-printed carbon electrodes (SPCE) functionalized with MXene-based three-dimensional nanomaterials are reportedfor rapid determinationof creatinine. Ti3C2TX MXene with in situ reduced AuNPs (MXene@AuNP) were used as a coreactant accelerator for efficient immobilization of enzymes. Creatinine could be oxidized by chitosan-embedded creatinine amidohydrolase, creatine amidinohydrolase, or sarcosine oxidase to generate H2O2, which could be electrochemically detected enhanced by Prussian blue (PB). The enzyme@CS/PB/MXene@AuNP/SPCE detected creatinine within the range 0.03-4.0mM, with a limit of detection of 0.01mM, with anaverage recovery of 96.8-103.7%. This indicates that the proposed biosensor is capable of detecting creatinine in a short amount of time (4min) within a ± 5% percentage error, in contrast with the standard clinical colorimetric method. With this approach, reproducible and stable electrochemical responses could be achieved for determinationof creatinine in serum, urine, or saliva. These results demonstrated its potential for deployment in resource-limited settings for early diagnosis and tracking the progression of chronic kidney disease (CKD).

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.

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.