Pre-Adsorbed H-Mediated Electrochemiluminescence.

In conventional electrochemiluminescence (ECL) systems, the presence of the competitive cathodic hydrogen evolution reaction (HER) in aqueous electrolytes is typically considered to be a side reaction, leading to a reduced ECL efficiency and stability due to H2 generation and aggregation at the electrode surface. However, the significant role of adsorbed hydrogen (H*) as a key intermediate, formed during the Volmer reaction in the HER process, has been largely overlooked. In this study, employing the luminol-H2O2 system as a model, we for the first time demonstrate a novel H*-mediated coreactant activation mechanism, which remarkably enhances the ECL intensity. H* facilitates cleavage of the O-O bond in H2O2, selectively generating highly reactive hydroxyl radicals for efficient ECL reactions. Experimental investigations and theoretical calculations demonstrate that this H*-mediated mechanism achieves superior coreactant activation compared to the conventional direct electron transfer pathway, which unveils a new pathway for coreactant activation in the ECL systems.

Regulating Reactive Oxygen Species over M-N-C Single-Atom Catalysts for Potential-Resolved Electrochemiluminescence.

The development of potential-resolved electrochemiluminescence (ECL) systems with dual emitting signals holds great promise for accurate and reliable determination in complex samples. However, the practical application of such systems is hindered by the inevitable mutual interaction and mismatch between different luminophores or coreactants. In this work, for the first time, by precisely tuning the oxygen reduction performance of M-N-C single-atom catalysts (SACs), we present a dual potential-resolved luminol ECL system employing endogenous dissolved O2 as a coreactant. Using advanced in situ monitoring and theoretical calculations, we elucidate the intricate mechanism involving the selective and efficient activation of dissolved O2 through central metal species modulation. This modulation leads to the controlled generation of hydroxyl radical (·OH) and superoxide radical (O2·-), which subsequently trigger cathodic and anodic luminol ECL emission, respectively. The well-designed Cu-N-C SACs, with their moderate oxophilicity, enable the simultaneous generation of ·OH and O2·-, thereby facilitating dual potential-resolved ECL. As a proof of concept, we employed the principal component analysis statistical method to differentiate antibiotics based on the output of the dual-potential ECL signals. This work establishes a new avenue for constructing a potential-resolved ECL platform based on a single luminophore and coreactant through precise regulation of active intermediates.

Potential-Resolved Ratiometric Aptasensor for Sensitive Acetamiprid Analysis Based on Coreactant-free Electrochemiluminescence Luminophores of Gd-MOF and "Light Switch" Molecule of [Ru(bpy)2dppz]2.

For conventional potential-resolved ratiometric electrochemiluminescence (ECL) systems, the introduction of multiplex coreactants is imperative. However, the undesirable interactions between different coreactants inevitably affect analytical accuracy and sensitivity. Herein, through the coordination of aggregation-induced emission ligands with gadolinium cations, the self-luminescent metal-organic framework (Gd-MOF) is prepared and serves as a novel coreactant-free anodic ECL emitter. By the intercalation of [Ru(bpy)2dppz]2+ with light switch effect into DNA duplex, one high-efficiency cathodic ECL probe is obtained using K2S2O8 as a coreactant. In the presence of acetamiprid, the strong affinity between the target and its aptamer induces the release of [Ru(bpy)2dppz]2+, resulting in a decreasing cathode signal and an increasing anode signal owing to the ECL resonance energy transfer from Gd-MOF to [Ru(bpy)2dppz]2+. In this way, an efficient dual-signal ECL aptasensor is constructed for the ratiometric analysis of acetamiprid, exhibiting a remarkably low detection limit of 0.033 pM. Strikingly, by using only one exogenous coreactant, the cross interference from multiple coreactants can be eliminated, thus improving the detection accuracy. The developed high-performance ECL sensing platform is successfully applied to monitor the residual level of acetamiprid in real samples, demonstrating its potential application in the field of food security.

A Controlled Release Aptasensor Utilizing AIE-Active MOFs as High-Efficiency ECL Nanoprobe for the Sensitive Detection of Adenosine Triphosphate.

Improving the sensitivity in electrochemiluminescence (ECL) detection systems necessitates the integration of robust ECL luminophores and efficient signal transduction. In this study, we report a novel ECL nanoprobe (Zr-MOF) that exhibits strong and stable emission by incorporating aggregation-induced emission ligands into Zr-based metal-organic frameworks (MOFs). Meanwhile, we designed a high-performance signal modulator through the implementation of a well-designed controlled release system with a self-on/off function. ZnS quantum dots (QDs) encapsulated within the cavities of aminated mesoporous silica nanoparticles (NH2-SiO2) serve as the ECL quenchers, while adenosine triphosphate (ATP) aptamers adsorbed on the surface of NH2-SiO2 through electrostatic interaction act as "gatekeepers." Based on the target-triggered ECL resonance energy transfer between Zr-MOF and ZnS QDs, we establish a coreactant-free ECL aptasensor for the sensitive detection of ATP, achieving an impressive low detection limit of 0.033 nM. This study not only demonstrates the successful combination of ECL with controlled release strategies but also opens new avenues for developing highly efficient MOFs-based ECL systems.

A Direct Z-Scheme AgBr/CuBi2O4 Photocathode for Ultrasensitive Detection of Ciprofloxacin and Ofloxacin by Controlling the Release of Luminol in Self-Powered Microfluidic Photoelectrochemical Aptasensors.

An innovative self-powered microfluidic photoelectrochemical (PEC) aptasensor was developed that uses photoactive AgBr/CuBi2O4 (ACO) composites as the photocathode matrix for ultrasensitive detection of ciprofloxacin (CIP) and ofloxacin (OFL). The formation of direct Z-scheme heterojunctions in ACO composites greatly aided electron/hole pair separation. Meanwhile, ZnIn2S4-decorated CdS nanorod arrays (CZIS) as the photoanode were used instead of a platinum counter electrode to provide electrons. The "signal-off" CIP detection was accomplished through the steric hindrance effect in the photoanode due to the combination of aptamer(CIP) and CIP. To increase the cathodic photocurrent intensity for OFL determination, controlled release of luminol was first used. Luminol molecules were successfully embedded in the porous structure of silicon dioxide nanospheres (PSiO2) by the electrostatic adsorption between PSiO2 and aptamer(OFL). The luminol released by specific recognition between OFL and aptamer(OFL) could not only react with •O2- but also produce chemiluminescence emission, resulting in the "signal-on" state. Because of the signal "on-off-on", the proposed aptasensor exhibited wide linear ranges for CIP (0.001-100 ng/mL) and OFL (0.0005-100 ng/mL) detection. Furthermore, the low detection limits of CIP (0.06 pg/mL) and OFL (0.022 pg/mL) could achieve the ultrasensitive analysis.

Whole-genome sequencing as an alternative to analyze copy number abnormalities in acute myeloid leukemia and myelodysplastic syndrome.

Copy number aberrations (CNA) are the core determinants for diagnosis, risk stratification and prognosis in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). In this study, a shallow whole-genome sequencing-based assay, LeukoPrint, was utilized to depict genomic CNA profiles from the bone marrow of 137 newly diagnosed AML/MDS patients. It demonstrated 98.1% concordance of CNA profiles with cytogenetics and/or fluorescence in situ hybridization (FISH). It is advantageous in detecting CNAs of short segments (1 Mb) and from samples with low leukemic cell content, more accurate for describing complex karyotypes and less confounded by subjective bias. LeukoPrint improved the overall diagnostic yield by redefining the risk categories for 16 patients by presenting new information. In summary, LeukoPrint provided an automated, convenient, and cost-effective approach to describe genomic CNA profiles. It brought greater diagnostic yield and risk stratification information by incorporating into the routine cytogenetics based on the CNA-related criteria of standard ELN/IPSS-R guidelines.

Dual Direct Z-Scheme Heterojunction with Growing Photoactive Property for Sensitive Photoelectrochemical and Colorimetric Bioanalysis.

A dual direct Z-scheme heterojunction photoactive material of CoTiO3/g-C3N4/Bi2O3 was designed based on calcination and in situ illumination-assisted process for sensitivity bioproteins detection which combined with MnO2 nanoflowers to achieve signal quenching strategy. The complex consists of two direct Z-scheme heterojunctions of g-C3N4 and two photoactive materials CoTiO3 and Bi2O3. This great structure could augment the migration of photogenerated electrons obviously, which boost the photocurrent greatly and prefer the photoelectric application of perovskite oxide. To improve sensitivity, the nanoflower like MnO2 with oxidation performance is introduced into the system and used as a label fixed on secondary antibody to oxidize electron donor (AA) to achieve an enlarged signal quenching value. Interestingly, MnO2 also showed an effective oxidation activity for TMB oxidation, leading to a chromogenic reaction. With the change of antigen concentration, the color of the test electrolyte also changes. Herein, the designed smart photoelectrochemical sensor shows a wide detection range (neuron specific enolase as an example) from 0.00005 to 200 ng/mL with a detection limit as low as 28 fg/mL. And the colorimetric assay for target detection owns a liner range from 0.1 to 20 ng/mL accompany with a detection limit of 0.05 ng/mL. These two designed sensing modes offer a new strategy for signal amplification of perovskite oxide and the possibility of real-time detection.

Designing Triangular Silver Nanoplates with GSH/GSSG Surface Mixed States as Novel Nanoparticle-based Redox Mediators for Electrochemical Biosensing.

Herein, a dual signal-quenched electrochemical (EC) biosensing strategy utilizing surface-engineered trisodium citrate (TSC)-glutathione (GSH)/oxidized glutathione (GSSG)-capped triangular silver nanoplates (Tri-Ag NPsTSC-GSH/GSSG) as a novel nanoparticle-based redox mediator was explored for biomarker determination. In contrast with conventional redox mediators, Tri-Ag NPsTSC-GSH/GSSG provided more admirable EC performance along with a lower oxidation potential (∼0.14 V). Taking advantage of the split-type mode, the immune response in a 96-well microplate was independent from EC detection, which could effectively eliminate the biological interference and thereby greatly enhance the sensitivity. As for the surface engineering process of Tri-Ag NPs, it was composed of partial GSH replacement and the formation of the GSH/GSSG surface mixed state. Primarily, the signal response of Ag NPsTSC-GSH decreased due to the hindrance of GSH on electron transfer. Moreover, varying proportions of GSH/GSSG could further impede the oxidation process of Tri-Ag NPsTSC-GSH/GSSG and eventually realize efficient dual signal quenching of this system. Notably, the ZIF-67@MIL-88B-GOx nanocomposite as the label was applied for a cascade reaction system with GSH peroxidase-like activities to form the optimal GSH/GSSG proportion, causing sensitive changes in signal response with a range of different antigen concentrations. On this basis, the fabricated biosensor provided measurable outputs of aflatoxin B1 concentrations in a linear range of 0.0005-50 ng/mL with a low detection limit of 0.61 pg/mL (S/N = 3). All of the results indicated that the novel biosensor could be a promising analytical tool for future biomarker detection.

Hollow Double-Shell CuCo2O4@Cu2O Heterostructures as a Highly Efficient Coreaction Accelerator for Amplifying NIR Electrochemiluminescence of Gold Nanoclusters in Immunoassay.

The evolution of electrochemiluminescence (ECL) emission amplified by coreaction accelerator in near-infrared (NIR) area has been overwhelmingly anticipated for ultrasensitive detection of disease biomarkers. Herein, the hollow double-shell CuCo2O4@Cu2O (HDS-CuCo2O4@Cu2O) heterostructures were conveniently prepared and utilized as an attractive coreaction accelerator to improve the NIR ECL performance of gold nanoclusters (AuNCs) for the first time. Benefiting from perfect-matched lattice spacing, unique Cu2O nanoparticles (NPs) were formed in situ on the layered-hollow CuCo2O4 nanospheres (NSs) to obtain HDS-CuCo2O4@Cu2O heterostructures. The formed heterojunctions supplied shorter charge transfer distance and better interfacial charge transfer efficiency as well as more effective separation performance. Consequently, HDS-CuCo2O4@Cu2O heterostructures as an admirable electroactive substrate could significantly promote the formation of sufficient coreactant intermediate radicals to react with AuNCs cationic radicals, realizing about 3-folds stronger NIR ECL response than that of individual AuNCs. In addition, the AuNCs templated by l-methionine (l-Met) exhibited NIR ECL emission around 830 nm, which could decrease the photochemical damage to even realize a nondestructive detection with improved susceptibility and circumambient adaptability. Subsequently, a well site-oriented fixation strategy utilizing HWRGWVC heptapeptide as the specific antibody immobilizer was introduced to further preserve the bioactivity of antibody on the HDS-CuCo2O4@Cu2O and AuNCs surface along with enhancing the incubation performance markedly. In view of the progressive sensing mechanism, a NIR immunosensor was obtained for the ultrasensitive analysis of CYFRA21-1, which achieved a broad linear ranging from 2 fg/mL to 50 ng/mL and a low limit of detection (LOD) of 0.67 fg/mL (S/N = 3).

Dumbbell Plate-Shaped AIEgen-Based Luminescent MOF with High Quantum Yield as Self-Enhanced ECL Tags: Mechanism Insights and Biosensing Application.

It is widely known that high-performance electrochemiluminescence (ECL) emitters play a crucial part in improving the detection sensitivity of the ECL strategy. Through the combination of aggregation-induced emission luminogens (AIEgens), 1,1,2,2-tetra(4-carboxylbiphenyl)ethylene (H4 TCBPE) with Zr(IV) cations, a dumbbell plate-shaped metal-organic framework (MOF) with high luminous efficiency is synthesized as ECL tags. The resultant MOF exhibits stronger ECL activity than those of H4 TCBPE monomers and aggregates. Herein, this phenomenon is defined as the coordination-triggered electrochemiluminescence (CT-ECL) enhancement effect. Furthermore, the nearly matched ECL and photoluminescence (PL) spectra imply the bandgap emission mechanism. Remarkably, polyethyleneimine (PEI) as the coreactant is covalently connected with MOF to form the uniquely self-enhanced ECL complex of Zr-TCBPE-PEI, where the robust ECL signal is captured owing to the intramolecular-like coreaction acceleration. Based on the resonance energy transfer (RET) behavior, the AuPd@SiO2 composite is designed as the high-efficiency quencher. In this manner, an innovative and ultrasensitive ECL sensor is constructed for neuron-specific enolase (NSE) detection through sandwich-type immunoreaction, with the detection limit down to 52 fg ml-1 . The present study has gone some way toward designing MOF-based self-luminescent ECL materials, thus paving a new avenue to expand the late-model ECL emitters for immunoassay.

Rationally engineered high-performance BiVO4/Ag3VO4/SnS2 photoelectrodes for ultrasensitive immunosensing of CYFRA21-1 based on HRP-tyramine-triggered insoluble precipitates.

A photoelectrochemical (PEC) biosensor capable of detecting cytokeratin 19 fragment 21-1 (CYFRA21-1) was optimized by taking advantage of the powerful conjugate repeats of horseradish peroxidase and tyramine (HRP-tyramine)-triggered enzymatic biocatalytic precipitation (BCP) on high-performance BiVO4/Ag3VO4/SnS2 photoelectrodes. Compared with the ubiquitous BCP strategy, we identified a design supporting conjugate repeats generated by HRP and tyramine-triggered immeasurable insoluble precipitates in the presence of hydrogen peroxide and 4-chloro-1-phenol (4-CN), and the steric hindrance improved sensitivity. Moreover, by virtue of BiVO4, Ag3VO4, SnS2 excellent level matching structure and chemical stability, a heterojunction (BiVO4/Ag3VO4/SnS2) with high light absorption efficiency has been successfully prepared. The novel heterostructure system of BiVO4/Ag3VO4/SnS2 with high detection current and low background signal exhibited high-performance PEC determination. Generally, the hitherto untapped biosensor resource realized the sensitive detection of CYFRA21-1 with a wide linear range from 50 fg/mL to 200 ng/mL, and a detection limit of 15 fg/mL, which illustrated the potential for biotechnological applications.

Original signal amplification assay for N-Terminal pro-brain natriuretic peptide detection based on Bi2MoO6 photosensitive matrix.

An original dual signal amplification immunoassay for N-Terminal pro-brain natriuretic peptide (NT-proBNP) detection is developed based on Au NPs and Zn doped CdS nanoparticles (Zn0.02Cd0.98S) co-sensitized Bi2MoO6 nanosheet photoelectrochemical (PEC) platform, the target is a good myocardial marker for diagnosing heart failure (HF). Bi2MoO6 as an outstanding photocatalysis material is successfully used in PEC analysis in this work, and the nanosheet structure provide a preponderance to capture superior Zn0.02Cd0.98S in order to achieve anticipant PEC response. The doping of Zn makes the energy band of CdS matched more compatible with Bi2MoO6, and improves the narrow band gap of CdS, making the surface plasma resonance (SPR) effect of Au NPs more significant, thus further improving the PEC response, as well as elevated the detection sensitivity of biological targets. The constructed PEC platform for NT-proBNP provides a wide detection range of 0.0001-1000 ng mL-1 and gives the minimum detection value of 0.037 pg mL-1. Great stability, high selectivity, and good reproducibility are also achieved. The proposed PEC immunoassay provides more possibilities for other protein ultra-sensitivity detection.

Exciton energy transfer-based fluorescent sensor for the detection of Hg2+ through aptamer-programmed self-assembly of QDs.

Herein, an original exciton energy transfer-based sensitive fluorescence sensor for the determination of Hg2+ has been designed through DNA aptamer-programmed self-assembly of CdTe quantum dots (QDs). In this work, CdTe QDs were applied as fluorescence signal source. The two pieces of T-rich aptamer played a role as molecular recognition probes which could bind to the target Hg2+ specifically. The extent of Hg2+-triggered self-assembly of QDs depended on the concentration of Hg2+, which resulted in an exciton energy transfer effect between QDs, giving an obvious fluorescence signal decrease and red-shift of the fluorescent peak. Based on this principle, we could detect the Hg2+ in two different signal modes. The limit of detection (LOD) was 3.33 nM. The proposed sensing method exhibited its application in detecting Hg2+ in real water samples with satisfactory performance. The results indicated that this proposed sensor will be of great potential in biological and analytical fields.

A "turn-off" fluorescent biosensor for the detection of mercury (II) based on graphite carbon nitride.

A novel and simple fluorescent biosensor has been realized through the fluorescence quenching of graphite carbon nitride (g-C3N4) for mercuric ion (Hg2+) detection. In this assay, the g-C3N4 sheets which were functionalized with single-stranded DNA (ssDNA) aptamer showed strong fluorescence emission at 440nm under the excitation of 380nm in the absence of Hg2+. When added to the assay solution, Hg2+ was embedded in the hairpin-shaped double-stranded DNA (dsDNA) due to the formation of the thymine-Hg2+-thymine (T-Hg2+-T) complex, which made the Hg2+ close to the surface of g-C3N4 sheet. Therefore, the fluorescence of g-C3N4 was quenched. This sensor has good selectivity with a limit of detection as low as 0.17nM under optimal conditions. The present work demonstrates that the g-C3N4-based fluorescent sensor has a promising application for detection of metal ions in real samples.

Highly selective fluorescent chemosensor for detection of Fe(3+) based on Fe3O4@ZnO.

The combination of fluorescent nanoparticles and specific molecular probes appears to be a promising strategy for developing fluorescent nanoprobes. In this work, L-cysteine (L-Cys) capped Fe3O4@ZnO core-shell nanoparticles were synthesized for the highly selective detection of Fe(3+). The proposed nanoprobe shows excellent fluorescent property and high selectivity for Fe(3+) due to the binding affinity of L-Cys with Fe(3+). The binding of Fe(3+) to the nanoprobe induces an apparent decrease of the fluorescence. Thus a highly selective fluorescent chemosensor for Fe(3+) was proposed based on Fe3O4@ZnO nanoprobe. The magnetism of the nanoprobe enables the facile separation of bound Fe(3+) from the sample solution with an external magnetic field, which effectively reduces the interference of matrix. The detection limit was 3 nmol L(-1) with a rapid response time of less than 1 min. The proposed method was applied to detect Fe(3+) in both serum and wastewater samples with acceptable performance. All above features indicated that the proposed fluorescent probe as sensing platform held great potential in applications of biological and analytical field.