Sensitive Electrochemiluminescence Research Articles

Enhanced Electrochemiluminescence from Ruthenium-Tagged Immune Complex at Flexible Chains for Sensitive Analysis of Glutamate Decarboxylase Antibody.

Herein, a sensitive electrochemiluminescence (ECL) immunosensor is designed by immobilizing ruthenium-tagged immune complexes at flexible poly-ethylene-glycol (PEG) chains on the electrode surface, which offers more freedom for the collision of the ruthenium complex at the electrode during the initial ECL reaction. The electrochemical characterizations confirm the loose structure of the assembled layer with the immune complex, providing an increase in the current and the resultant enhanced ECL emissions. Comparing the sensors with the rigid structure, a 34-fold increase in the maximal ECL emission is recorded when PEG3400 is used as a linker. Using the optimized protocol, the prepared immunosensor exhibits a wide-ranging linear response to the model antibody (glutamate decarboxylase antibody) ranging from 10 pg/mL to 10 ng/mL. The detection limit is almost two orders lower than the value using the classic enzyme-linked immunosorbent assay, which offers a new design to enhance ECL emissions and the resultant analytical performance.

Highly electroactive thiazolium [5,4-d]thiazol-2,5-dicarboxylicacid-silver electrochemiluminescent metal-organic frameworks: synthesis, properties and application in glutathione detection.

Thiazolo[5,4-d]thiazole-2,5-dicarboxylic acid (H2Thz), a thiazolothiazole (TTz) derivative with carboxylic acid groups, was synthesized as a ligand for the creation of five MOFs, each associated with distinct metal ions including Ag+, Mn2+, Co2+, Zn2+, and Cu2+. The cathodic electrochemiluminescence (ECL) of H2Thz and the resulting MOFs was investigated. H2Thz was found to generate ECL signals, but this process was heavily reliant on potassium persulfate (K2S2O8) as a co-reactant. However, the Ag-MOF, formed with H2Thz as the ligand, exhibited substantial ECL signals without the need for any co-reactant, which is different from other metal-containing MOFs. The smaller band gap, higher electron mobility and the unique electrocatalytic activity of Ag+ ions were confirmed to be the reasons for the excellent ECL performance of Ag-MOF. The interaction between thiol group of glutathione (GSH) and Ag-MOF suppressed the ECL signal of the Ag-MOF-K2S2O8 system. Based on this, a sensitive ECL method for GSH was developed and effectively utilized for GSH quantification in cell lysates.

Nb2CTx-supported bimetallic NPs@ZIF-8 nanohybrid as ECL signal amplifier and peroxidase mimics for chromogranin a immunosensing in human serum and saliva.

Niobium carbide (Nb2CTx), a key component of the MXene family renowned for its utilization in lithium-ion batteries and supercapacitors, remains largely underutilized in biosensing applications. This study introduces a notably sensitive and label-free dual-mode electrochemiluminescence (ECL) and colorimetric immunosensor to specifically detect chromogranin A (CgA) in biological fluids. Initially, AuAg bimetallic nanoparticles (BiMNPs) were synthesized using Nb2CTx as a reducing and supporting material. Furthermore, a promising approach has been put forward to increase the efficacy of the ECL of [Ru (bpy)3]2+ system by integrating the combined use of the zeolitic imidazolate framework-8 (ZIF-8) and the Nb2CTx coated bimetallic NPs. Incorporation produces a significant ~165-fold increase in electrochemical signals and a 4-fold improvement in ECL signals. In particular, BiMNPs@ZIF-8 nanohybrid exhibited significantly enhanced peroxidase-like activity compared to bare BiMNPs, demonstrating synergistic peroxidase enzyme mimicry. This improved activity makes it a potent catalyst for the H₂O₂-mediated oxidation of 3,3,5,5, tetramethylbenzidine (TMB), generating the characteristic blue color. Furthermore, the ECL method achieved a detection range of 0.001 to 1000 pg/mL with LOD of 0.11 fg/mL, while the colorimetric method achieved a LOD of 100 pg/mL and a linear range of 0.1 to 4000 ng/mL. The practical applicability of the sensor was validated by analyzing CgA levels in human serum and saliva samples.

The rational design of europium complex based electrochemiluminescence sensor for highly efficient carbaryl detection.

To address the issue that most of the reported electrochemiluminescence (ECL) sensors are usually subjected to various complicated chemical modifications, we proposed a sensitive ECL sensor by using a neutral mononuclear lanthanide metal europium complex Eu(L)3 (L=2-pyrazol-1-yl-6-(1H-tetrazol-5-yl)-pyridine) as luminophore with simple chemical composition for the accurate detection of carbaryl pesticide residues. The three conjugated tridentate pyrazo-pyridine- tetrazol ligands could put significant effect on the physical and chemical behavior of the central Eu3+ ion, leading to the excellent luminescent performance of the Eu(L)3 complex enhanced by "antenna effect" of the auxiliary anionic organic ligands. The naphthol obtained from the hydrolysis reaction of carbaryl in an alkaline working solution could effectively and quantitatively quench the luminescence intensity of the Eu(L)3 complex, which has been theoretically confirmed by the detailed density functional theory (DFT) and time-dependent DFT (TDDFT) calculations, thus obviously strengthening the target detection capability on carbaryl. Based-on such the idea, the skillfully constructed ECL sensor showed superior carbaryl detection performance with good linearity in the range of 1pg/mL to 1000ng/mL, and a satisfied detection limit of 8.8pg/mL (S/N=3) under the optimized conditions. The current simple ECL carbaryl detection platform exhibited the conspicuous superiority to those existed commercial ones and thus, more importantly, provided a very promising practical value in the field of environmental detection (oil, soil, water, etc.) of organic phenol pollutants.

Enhanced Electrochemiluminescence by Knocking Out Gold Active Sites.

Electrochemiluminescence (ECL) of the conventional system of [Ru(bpy)3]2+ luminophore and amine-based coreactants is particularly inefficient on noble metal electrodes. This is due to the formation of a passivating oxide layer on the metal surface inhibiting the electro-oxidation of amines like tri-n-propylamine (TPrA) coreactant, Herein, we demonstrated the enhancement of ECL emission on gold surface by hydroxyl radicals attack that are chemically generated with Cu-Fenton reagent. These radicals selectively deactivate the gold active sites and knockout the metal surface asperities that counterintuitively led to an amplification of the ECL emission. Atomic Force Microscopy shows a massive smoothening of the surface. The electrochemical characterization proves that the involved ECL reaction mechanism switches from direct oxidation to catalytic route, where the kinetics of indirect TPrA oxidation is facilitated on deactivated gold surface. Besides, in situ smoothening of a rough electrode in presence of tandem [Ru(bpy)3]2+/TPrA, the ECL enhancement enables Cu2+ sensing with good reliability and limit of detection. Such atomically smoothened and corrosion-resistant gold surface readily tuned the ECL reactivity and opened new directions on influence of topography and reactivity on ECL mechanisms, thus will be extremely useful for the future development of ECL imaging strategies and highly sensitive ECL sensors.

Enhanced Electrochemiluminescence by Knocking Out Gold Active Sites

Electrochemiluminescence (ECL) of the conventional system of [Ru(bpy)3]2+ luminophore and amine‐based coreactants is particularly inefficient on noble metal electrodes. This is due to the formation of a passivating oxide layer on the metal surface inhibiting the electro‐oxidation of amines like tri‐n‐propylamine (TPrA) coreactant, Herein, we demonstrated the enhancement of ECL emission on gold surface by hydroxyl radicals attack that are chemically generated with Cu‐Fenton reagent. These radicals selectively deactivate the gold active sites and knockout the metal surface asperities that counterintuitively led to an amplification of the ECL emission. Atomic Force Microscopy shows a massive smoothening of the surface. The electrochemical characterization proves that the involved ECL reaction mechanism switches from direct oxidation to catalytic route, where the kinetics of indirect TPrA oxidation is facilitated on deactivated gold surface. Besides, in situ smoothening of a rough electrode in presence of tandem [Ru(bpy)3]2+/TPrA, the ECL enhancement enables Cu2+ sensing with good reliability and limit of detection. Such atomically smoothened and corrosion‐resistant gold surface readily tuned the ECL reactivity and opened new directions on influence of topography and reactivity on ECL mechanisms, thus will be extremely useful for the future development of ECL imaging strategies and highly sensitive ECL sensors.

Development of a Sensitive and Reliable Meso Scale Discovery-Based Electrochemiluminescence Immunoassay to Quantify TDP-43 in Human Biofluids.

Transactive response DNA-binding protein of 43 kDa (TDP-43) is a major component of pathological inclusions in various neurodegenerative disorders, including amyotrophic lateral sclerosis and frontotemporal lobar degeneration. The detection of TDP-43 in biofluids is crucial for the development of diagnostic and prognostic indicators of disease and therapeutic development for TDP-43-related proteinopathies. Despite its potential as a biomarker for numerous neurological disorders, the lack of a sensitive and reproducible TDP-43 assay hinders progress in TDP-43-based therapy development, underscoring the need for an effective and standardized method for accurate quantification. Addressing the limitations of sensitivity and reproducibility in existing assays, in this study, we developed and validated a highly sensitive electrochemiluminescence immunoassay on the Meso Scale Discovery platform. The assay demonstrated the detection of full-length TDP-43 in human biofluids with a limit of detection of 4pg/mL, a working range of 4-20,000 pg/mL, and a total assay time of 16 h. In this study, we developed and validated a sensitive immunoassay for the detection of full-length TDP-43 in human biofluids using the Meso Scale Discovery platform. We used this immunoassay to quantify TDP-43 levels in the plasma and serum of healthy controls and ALS patients. Our results indicate a reduction in full-length TDP-43 in the blood of ALS patients compared to healthy controls.

Dual-site responsive module-triggered CRISPR/Cas12a switch with enhanced reaction kinetics for specific detection of PSA

Despite advances in DNA-based nanodevices for tumor biomarker detection, the pursuit of enhanced sensitivity and specificity remains a profound challenge. In this study, we designed an integrated dual-site responsive module as the AND logic gate that responded to both prostate-specific antigen (PSA) and apurinic/apyrimidinic endonuclease 1 (APE1), triggering a tetrahedral DNA nanostructure (TDN)-accelerated CRISPR/Cas12a signal switch for PSA detection. In detail, the dual-site responsive module was a T-shaped probe comprised of three DNA strands, which contained PSA aptamer and apurinic/apyrimidinic (AP) sites, significantly improving the specificity of prostate cancer screening by orthogonal recognition of PSA and APE1. When both PSA and APE1 were present, PSA could specifically bind with the aptamer, while APE1 catalyzed and cleaved the AP sites, releasing a part of one auxiliary strand as the mimic target (MT). To enhance the trans-cleavage efficiency of the CRISPR/Cas12a signal switch, we parallelly constructed the TDN with extended non-target strands (NTS) at each vertex, which could capture the MT to form double-stranded DNA (dsDNA) activators at the TDN vertices (TDN-activators) for triggering the CRISPR/Cas12a signal switch. Benefiting from the rigid framework of TDN, the TDN-activators not only increased the local concentration of Cas12a but also enabled a dominant conformation that was more favorable for recognizing and activating the Cas12a-crRNA complex, which demonstrated a 4.06-fold increase in trans-cleavage efficiency compared to that of dsDNA-activated Cas12a. This work applies the T-shaped probes and TDN-accelerated CRISPR/Cas12a signal switch to achieve the specific and sensitive electrochemiluminescence (ECL) detection of PSA from 1.0 × 10−5 to 10 μg/mL with a low limit of detection (LOD) of 4.5 × 10−6 μg/mL, offering a promising tool for early clinical screening of prostate cancer.

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.

Tetraphenylethene-Based Covalent Organic Polymers with Aggregation-Induced Electrochemiluminescence for Highly Sensitive Bacterial Biosensors.

Tetraphenylethene (TPE), which usually serves as aggregation-induced emission and aggregation-induced electrochemiluminescence fluorophores, has been widely applied in fabricating fluorescent nanomaterials and biosensors. However, it is still a tremendous challenge to prepare well-controlled TPE aggregates with strong fluorescence (FL) and electrochemiluminescence (ECL). In this study, we constructed a bacterial ECL biosensing platform with high sensitivity based on TPE-based covalent organic polymer (COP) nanoparticles synthesized by a simple Menschutkin reaction strategy to employ bromide group-carrying molecules and 1,1,2,2-tetrakis(4-(pyridine-4-yl)phenyl)ethene as the cross-linking agent and the emissive moiety, respectively. The ECL Escherichia coli biosensor had high sensitivity, a low limit of detection (0.19 CFU mL-1), a wide linear range (1 × 102-5 × 106 CFU mL-1), and good selectivity. The excellent properties of the bacterial biosensor could be attributed to the uniform spherical COP nanoparticles with enhanced FL and ECL signals, the maximal ECL efficiency of which was 8.4-fold higher than that of the typical tris(bipyridine) ruthenium(II) emitter. The FL and ECL intensities of the TPE-based COP nanoparticles could be adjusted by varying bromide group-carrying molecules and thus regulating their energy gap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) orbitals. The TPE-based COP nanoparticles with strong FL and ECL intensities pave a promising avenue to construct highly sensitive bacterial ECL biosensors for the large-scale screening of disease-causing bacteria.

Electrochemiluminescence Reveals the Structure-Catalytic Activity Relationship of Heteroatom-Doped Carbon-Based Materials.

Heteroatom doping can change the chemical environment of carbon-based nanomaterials and improve their catalytic performance. Exploring the structure-catalytic activity relationship of heteroatom-doped carbon-based materials is of great significance for studying catalytic mechanisms and designing highly efficient catalysts, but remains a significant challenge. Recently, reactive oxygen species (ROS)-triggered electrochemiluminescence (ECL) has shown great potential for unveiling the mechanism by which heteroatom-doped carbon-based materials catalyze the oxygen reduction reaction (ORR), owing to the high sensitivity of these materials to the properties of the electrode surface. Herein, two kinds of heteroatom-doped porous carbon (denoted as NP-C and N-C) are synthesized and analyzed by monitoring the cathodic ECL of luminol-H2O2 in the low negative-potential region. P, N-doped NP-C exhibitsbetter catalytic ability for activating H2O2 to generate large amounts of •OH and O2 •-, compared with N-C. A sensitive antioxidant-mediated ECL platform is successfully developed for detecting the antioxidant levels in cells, exhibiting considerable potential for evaluating the antioxidant capacity. The relationship between the structure and catalytic mechanism of heteroatom-doped carbon-based materials is successfully explored using ECL, where this method can be universally applied to carbon-based materials.

Self-Replicating Catalytic Hybridization Assembly of Bipedal DNAzyme Walkers for Enhanced Electrochemiluminescence Bioanalysis.

Dynamic DNA nanodevices, particularly DNA walkers, have proven to be versatile tools for target recognition, signal conversion, and amplification in biosensing. However, their ability to detect low-abundance analytes in complex biological samples is often compromised by limited amplification depth and severe signal leakage. To address these challenges, we developed a simple yet highly efficient strategy to engineer a self-replicating bipedal DNAzyme (SEDY) walker for sensitive and selective electrochemiluminescence (ECL) bioanalysis. Unlike conventional DNA walkers that are typically constructed by catalytic DNA assembly in a single direction, the SEDY walker integrates a self-replicating feedback mechanism that greatly enhances both the selectivity and sensitivity of bioanalysis. First, the SEDY walker is assembled through a target-triggered, enzyme-free, self-replicating catalytic approach, minimizing the risk of undesired side reactions and signal leakage by simplifying reactant complexity. Furthermore, the SEDY walker features newly exposed trigger sequences that facilitate its autonomous replication, leading to a robust and exponential amplification of its products. Our experiments demonstrate that the SEDY walker can sensitively and selectively detect acetamiprid by navigating specific probes within cross-shaped DNA orbits. The ECL biosensor offers a linear detection range from 1 × 10-15 M to 1 × 10-9 M, with a limit of detection as low as 5.8 × 10-16 M. We anticipate that the SEDY walker will be a powerful tool for detecting various analytes in biological applications.

A sensitive electrochemiluminescence immunosensor for CEA detection based on the ECL-RET between zinc-based metal–organic frameworks and ZiF-8@PDA

In this study, we developed a new system that using zinc-based metal–organic frameworks NH2-Zn-PTC as the donor and ZiF-8@PDA as the acceptor to achieve highly sensitive detection of carcinoembryonic antigen (CEA), using the fundamentals of electrochemiluminescence resonance energy transfer (ECL-RET). Firstly, the aggregation-induced quenching effect (ACQ) was eliminated by the coordination of PTC in MOF and the ECL signal was improved. Secondly, the ECL signal was further amplified by using Au NPs and amino groups as co-reaction promoters to generate more SO4.−. In addition, the introduction of ZiF-8@PDA as an acceptor and NH2-Zn-PTC as a donor took advantage of the feature of partial overlap of the UV–vis absorption spectrum and ECL emission spectra between the two, thereby effectively initiating the ECL-RET behavior, which improved the detection sensitivity of the sensor. The prepared immunosensor showed good linearity in the concentration range of 10−4 to 80 ng/mL with a detection limit of 18.20 fg/mL. This makes it promising for clinical testing of tumor markers.

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.

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.

Interfacial Conductor-Modulated Low-Triggered Potential Electrochemiluminescence from Conjugated Polymers for Bioanalysis.

Polyfluorene and its derivatives (PFs) are extremely appealing electrochemiluminescence (ECL) illuminants thanks to their easy modification, high quantum yield, excellent photostability, and nontoxicity, exhibiting great application potential in ECL sensing and imaging. Unfortunately, most reported PFs-based ECL bioanalysis generally exhibited high triggering potential (>1.0 V vs Ag/AgCl), which introduced undesirable electrochemical interference to adversely affect the sensitivity and accuracy of biological analysis. This work innovatively exploited poly(3,4-ethylenedioxythiophene) (PEDOT) as an interfacial conductor to modulate the low ECL triggering potential of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3}-thiadazole)] (PFBT) nanoparticles (NPs). The unique conductivity of in situ electrodeposited PEDOT promoted electron transfer between PFBT NPs and coreactant tripropylamine (TPrA), negatively shifting the ECL triggering potential of PFBT NPs from +1.22 to +0.78 V. The PFBT NPs/PEDOT coupled the localized hybridization chain reaction (LHCR) circuits to achieve a specific and sensitive ECL detection of malathion (MAL), and a low limit of detection (LOD) of 22 fg/mL was obtained. The interfacial conductor provides inspiration for creating the low ECL triggering potential. PFBT NPs-coupled PEDOT builds a low ECL triggering potential of the PFs-based platform for pesticide residue analysis with low interference and high sensitivity.

Highly Sensitive Electrochemiluminescence Biosensing Method for SARS-CoV-2 N Protein Incorporating the Micelle Probes of Quantum Dots and Dibenzoyl Peroxide Using the Screen-Printed Carbon Electrode Modified with a Carboxyl-Functionalized Graphene.

Obtaining stable electrochemiluminescence (ECL) emissions from a hydrophobic luminophore in aqueous solutions and designing a method without the use of an exogenous coreactant are promising for ECL biosensing. Here, a highly sensitive signal-on ECL immunoassay for the SARS-CoV-2 N protein was developed using micelles as an ECL tag. The micelles were prepared by coencapsulating the luminophore hydrophobic CdSe/ZnS quantum dots and coreactant dibenzoyl peroxide within the hydrophobic core of micelles. The ECL probe was obtained by covalently bonding a SARS-CoV-2 N protein-binding aptamer onto the micelle surface. The construction of the immunosensor was initiated by the immobilization of the anti-SARS-CoV-2 N protein antibody onto the screen-printed carbon electrode (SPCE) with a -COOH-functionalized surface. The surface functionalization of SPCEs was achieved through paste-exfoliated graphene, which was modified with a -COOH group through supramolecular-covalent scaffolds on SPCE. Upon achieving sandwich complexes on the immunosensor, an efficient ECL signal response at -1.4 V versus Ag/AgCl was obtained in phosphate buffer solution. The ECL assay was used for the sensitive determination of SARS-CoV-2 N protein with the linear range from 0.01 to 50 ng mL-1, and the detection limit was 3.0 pg mL-1. The immunosensor showed good reproducibility and stability, and the ECL immunoassay was used to determine the SARS-CoV-2 N protein in serum samples. The proposed approach to obtain micelles is versatile for the preparation of stable ECL luminophores by using hydrophobic materials, and the strategy provides an alternative for ECL bioassays based on the coreactant route.

Electrochemiluminescence biosensor for P-tau217 based on target-induced change of the steric hindrance effect of an antibody-modified electrode

Tau protein extensively phosphorylated at threonine 217 (p-tau217), has emerged with significant potential for initial clinical identification of Alzheimer’s disease (AD). In this study, a simple but sensitive electrochemiluminescence (ECL) immunosensor was designed for p-tau217 detection based on antigen–antibody specific binding to modulate the spatial hindrance of the gold electrode interface. Silica nanoparticles doped with ruthenium bipyridine (Ru@SiO2 NPs) were used as the ECL indicator. The p-tau217 monoclonal antibody was initially fixed onto the gold electrode surface, selectively capturing the p-tau217 protein, which subsequently increased the steric hindrance of the electrode. This process allowed for a decreased amount of Ru@SiO2 to access the electrode surface, which resulted in the relatively low ECL intensity being detected. The variation in ECL intensity exhibited a strong linear correlation with the logarithm of the target concentration, spanning from 1 pg/mL to 100 ng/mL, and a detection limit of 0.178 pg/mL was achieved. The proposed approach was effectively implemented to detect target in the serum of AD patients, and it delivered satisfactory outcomes.

Sensitive and quick electrochemiluminescence biosensor for the detection of reactive oxygen species in seminal plasma based on the valence regulation of gold nanoclusters

BackgroundGold nanoclusters (AuNCs) obtained by electroreduction have excellent electrochemiluminescence (ECL) properties, and its ECL intensity is regulated by the valence state. In addition, their ECL signals can be rapidly quenched by reactive oxygen species (ROS). Based on this observation, a sensitive ROS biosensor was designed based on valence regulation of AuNCs. Excessive ROS in seminal plasma can lead to male infertility, and the short half-life and instability of ROS pose a challenge for their detection. Since valence regulation can be done quickly and is very sensitive, this ECL biosensor holds promise to address this issue. ResultsThe ECL mechanism of AuNCs and the quenching mechanism of AuNCs by ROS were explored, mainly because ROS change the valence state of AuNCs. The ECL signals of the biosensor have a linear relationship with logarithm of the target concentration in the range of 1.0 × 10−8 to 1.0 × 10−3 M and 1.0 × 10−3 to 1.0 × 10−1 M, with a detection limit of 0.75 × 10−10 M (S/N = 3). The biosensor enables rapid one-step detection of ROS and has the advantage of being stable and reusable. More notably, the results of 57 real samples showed that the biosensor can be used to accurately assess the concentration of seminal plasma ROS, guiding the monitoring of sperm quality and the diagnosis of male infertility. SignificanceCompared with the traditional strategy of applying AuNCs only as a luminescent body, this strategy of regulating the valence state of AuNCs to achieve sensitive and rapid detection broadens the application of AuNCs in the field of analysis. Compared with other ROS detection strategies, the one-step immediate detection method effectively avoids the inaccuracy caused by the short half-life and natural dissipation of ROS, and is expected to improve the accuracy and efficiency of clinical diagnosis.

A fluorescence-validated MIP-ECL sensor based on UiO66 loaded carbon nitride for detection of trace Patulin in series fruit products

Trace-level mycotoxin patulin (PAT) exposure causes serious harm to human health. Herein, a fluorescence (FL)-validated molecularly imprinted polymer (MIP)-electrochemiluminescence (ECL) sensor based on zirconium metal organic frameworks loaded carbon nitride (UiO66@CN) for detection of trace PAT was proposed. UiO66@CN, with abundant-NH2 groups, excellent thermal and aqueous stability compared to CN, was prepared by a simple one-pot method. And it not only has excellent ECL performance, but also has reliable FL visualization properties. MIPs with 3D cavity containing specific PAT recognition sites were imprinted on UiO66@CN modified indium tin oxide by self-polymerization. The binding process of PAT molecules with MIP acted as a gate to control the FL and ECL signals. Notably, visualized FL and sensitive ECL were innovatively implemented in a sensing system. With the help of FL mode validation, PAT was accurately detected in the ECL mode with a detection limit of 50 fg mL−1. In addition, when proposed method and high-performance liquid chromatography (HPLC) were simultaneously applied to fruit products, the results obtained were in complete agreement. Thus, the assay provided a new approach to achieve low-cost, accurate and practical detection of trace toxins.