Combination of core-shell structured NH2-UiO-66@ZIF-8 loaded Ru (bpy)3 2+ and molecularly imprinted copolymer for the sensitive ECL detection of tetracycline.

A molecularly imprinted electrochemiluminescent sensor is developed for the sensitive detection of tetracycline in environmental and food samples. The sensor uses an ionic liquid (i.e. [APMIM]Br) modified graphene-carbon nanotube composite (GMI) material as substrate, a double-layered core-shell metal-organic framework NH2-UiO-66@ZIF-8 (NUZ) loaded bipyridyl ruthenium (NUZ@Ru) as luminescent material, and a molecularly imprinted copolymer of o-phenylenediamine and hydroquinone as recognition element. The ionic liquid-modified graphene-carbon nanotube composite has a favorable three-dimensional structure, high specific surface area, and good hydrophilicity; the core-shell structured metal-organic framework has high stability and plentiful reaction sites for loading; the molecularly imprinted copolymer film has enhanced stability and recognition effect. Hence, the resulting sensor combines the merits of several materials and presents improved performance. Under the optimum detection conditions, it shows a wide linear range of 0.05 µM - 1 mM, a low detection limit of 20 nM, high selectivity, and excellent stability. It has been successfully applied to the detection of tetracycline in different samples.

Electrochemiluminescent bioassay based on Ru@Zr-BTC-MOFs nanoparticles for determination of let-7a miRNA using the hybridization chain reaction.

Carboxyl-rich tris(4,4'-dicarboxylic acid-2,2'-bipyridyl) ruthenium(II) ([Ru(dcbpy)3]2+) and 1,3,5-phenyl tricarboxylic acid (H3BTC) were used as the organic ligand to synthesize the metal-organic frameworks by a simple one-pot hydrothermal method with ZrCl4 as metal ion source. Subsequently, the excellent electrochemiluminescence (ECL) luminophore (denoted as Ru@Zr-BTC-MOFs) was obtained. The Ru@Zr-BTC-MOFs displayed outstanding ECL properties, and a sensitive ECL bioassay based on Ru@Zr-BTC-MOFs was designed for the detection of let-7a microRNA (miRNA) using hybrid chain reaction (HCR). Under the optimal experimental conditions, the proposed bioassay exhibited a good linear relationship in the range from 50.0 fM to 5.00 × 102 pM with a detection limit of 3.71 fM. Besides, the proposed sensor exhibited satisfactory performance in real samples. The recovery was 91 ~ 108%, and the relative standard deviation was less than 5.6%. It might have potential clinical applications for detecting miRNA in biomedical research and clinical diagnosis. The schematic diagram of the preparation of Ru@Zr-BTC-MOFs (a) and ECL sensor for detecting let -7a (b).

Molecular imprinting electrochemiluminescence sensor based on nitrogen-doped carbon quantum dots /Ru(bpy)3@SiO2 for the determination of citrinin.

An electrochemiluminescence (ECL) sensor based on molecular imprinting polymer and SiO2 nanoparticles loaded Ru(bpy)3 and nitrogen-doped carbon quantum dots (NCQDs) is constructed for citrinin detection. The Ru(bpy)3 acts as ECL emitter, and the NCQDs cooperate with tri-n-propylamine (TPA) in solution as a coreactant to facilitate the luminescence. The citrinin imprinted poly(p-aminothiophenol) film is deposited on the surface of the luminophore by electrochemical method, which can immobilize the luminophore besides recognizing the target. The obtained ECL sensor exhibits high sensitivity, stability, and reproducibility. The change of ECL intensity and the logarithm of citrinin concentration display a good linear relationship in the range 1.0 to 100 pg mL-1, and the detection limit is 5 fg mL-1. When it is applied to the detection of citrinin contents in food sample (i.e., rice and millet) solutions, the RSD is less than 6.1%, and the recoveries for spiked standards range from 95.5 to 102.0%. Hence, this work provides a promising alternative for citrinin detection.

A sensitive signal-on electrochemiluminescence sensor based on a nanocomposite of polypyrrole-Gd2O3 for the determination of L-cysteine in biological fluids.

A sensitive solid-state electrochemiluminescence (ECL) electrode for L-cysteine was developed based on depositing layers of a hybrid nanocomposite of polypyrrole-dodecyl benzene sulfate-sodium perchlorate-sodium carbonate-gadolinium (PPy-Gd2O3) on a platinum substrate. The presence of the Gd2O3 nanoparticle layer improved the ECL signal, and under optimum conditions, a linear relationship was observed between the signal and the logarithm of L-cysteine concentration from 1.0 × 10-13 to 1.0 × 10-6 M (R2 = 0.9937). At the emission wavelength around 425 nm , at which the analytical signal was measured, the electrode showed an RSD of less than 4% and a low detection limit of 4.2 × 10-14 M. The results proved to be reproducible and stable, and the electrode was applicable in the determination of L-cysteine in biological fluids with recoveries from 94.0-107%. Graphical abstract The results of this research indicated that the weak ECL of luminol is greatly improved by traces of L-cysteine on a solid-state platinum electrode coated with polypyrrole and gadolinium oxide nanoparticles (NPs) and have hence been effectively used in the analysis of L-cysteine in plasma and saliva.

Highly Selective Electrochemiluminescence Sensor Based on Molecularly Imprinted-quantum Dots for the Sensitive Detection of Cyfluthrin.

A highly selective and sensitive molecularly imprinted electrochemiluminescence (MIECL) sensor was developed based on the multiwall carbon nanotube (MWCNT)-enhanced molecularly imprinted quantum dots (MIP-QDs) for the rapid determination of cyfluthrin (CYF). The MIP-QDs fabricated by surface grafting technique exhibited excellent selective recognition to CYF, resulting in a specific decrease of ECL signal at the MWCNT/MIP-QD modified electrode. Under optimal conditions, the MIECL signal was proportional to the logarithm of the CYF concentration in the range of 0.2 µg/L to 1.0 × 103 µg/L with a determination coefficient of 0.9983. The detection limit of CYF was 0.05 µg/L, and good recoveries ranging from 86.0% to 98.6% were obtained in practical samples. The proposed MIECL sensor provides a novel, rapid, high sensitivity detection strategy for successfully analyzing CYF in fish and seawater samples.

A ratiometric molecular imprinted electrochemiluminescence sensor based on enhanced luminescence of CdSe@ZnS quantum dots by MXene@NaAsc for detecting uric acid.

An unlabeled ratiometric molecular imprinted electrochemiluminescence sensor was developed for the determination of trace uric acid, based on MXene@NaAsc nanocomposites, CdSe@ZnS quantum dots and molecularly imprinted polymer composites modified glass carbon electrode. MXene@NaAsc stably enhanced the electron transfer and improved electrochemiluminescence intensity by acting as a base platform and signal amplifier for CdSe@ZnS quantum dots. Specific molecular imprinting cavities based on electropolymerization with o-phenylenediamine were formed to specifically identify uric acid. Combining the good sensitivity of electrochemiluminescence and the excellent selectivity of molecularly imprinted polymer, the ratio of optical signal and electrical signal was used as a comprehensive signal to achieve the detection of uric acid. Based on this, uric acid was detected in the range from 1 × 10-10 to 1 × 10-4 mol/L with the LOD of 18.13 pmol/L (S/N = 3). The developed sensor with easy preparation, great selectivity and excellent sensitivity could successfully detect uric acid in human serum.

Solid Electrochemiluminescence Sensor by Immobilization of Emitter Ruthenium(II)tris(bipyridine) in Bipolar Silica Nanochannel Film for Sensitive Detection of Oxalate in Serum and Urine.

Convenient and highly sensitive detection of oxalate ions in body fluids is of crucial significance for disease prevention, diagnosis, and monitoring of treatment effectiveness. Establishing a simple solid-state electrochemiluminescence (ECL) sensing system for highly sensitive detection of oxalate ions is highly desirable. In this work, a solid ECL sensor was fabricated by immobilizing the commonly used emitter ruthenium(II)tris(bipyridine) (Ru(bpy)32+) on a double-layered bipolar silica nanochannel array film (bp-SNA)-modified electrode, enabling sensitive detection of oxalate ions in serum or urine samples. Cost-effective and readily available indium tin oxide (ITO) was used as the supporting electrode. Convenient fabrication of multiple negatively charged SNA (n-SNA)-modified ITO electrodes was achieved through the one-step Stöber solution growth method. Subsequently, a positive outer layer film (p-SNA) was rapidly prepared using an electrochemical-assisted self-assembly method. The double-layered bipolar silica nanochannel array film achieved stable immobilization of Ru(bpy)32+ on the electrode surface, facilitated by the electrostatic adsorption of Ru(bpy)32+ by n-SNA and the electrostatic repulsion by p-SNA. Utilizing oxalate ions as a co-reactant for Ru(bpy)32+, combined with the electrostatic enrichment of oxalate ions by p-SNA, the constructed sensor enabled highly sensitive detection of oxalate ions ranging from 1 nM to 25 µM and from 25 µM to 1 mM, with a detection limit (LOD) of 0.8 nM. The fabricated ECL sensor exhibited high selectivity and good stability, making it suitable for ECL detection of oxalate ions in serum and urine samples.

Ternary electrochemiluminescence quenching effects of CuFe2O4@PDA-MB towards self-enhanced Ru(dcbpy)32+ functionalized 2D metal-organic layer and application in carcinoembryonic antigen immunosensing.

BACKGROUND: Carcinoembryonic antigen (CEA) is a significant glycosylated protein, and the unusual expression of CEA in human serum is used as a tumor marker in the clinical diagnosis of many cancers. Although scientists have reported many ways to detect CEA in recent years, such as electrochemistry, photoelectrochemistry, and fluorescence, their operation is complex and sensitivity is average. Therefore, finding a convenient method to accurately detect CEA is significance for the prevention of malignant tumors. With high sensitivity, quick reaction, and low background, electrochemiluminescence (ECL) has emerged as an essential method for the detection of tumor markers in blood. RESULTS: In this work, a "signal on-off" ECL immunosensor for sensitive analysis of CEA ground on the ternary extinction effects of CuFe2O4@PDA-MB towards a self-enhanced Ru(dcbpy)32+ functionalized metal-organic layer [(Hf)MOL-Ru-PEI-Pd] was prepared. The high ECL efficiency of (Hf)MOL-Ru-PEI-Pd originated from the dual intramolecular self-catalysis, including intramolecular co-reaction between polyethylenimine (PEI) and Ru(dcbpy)32+. At the same time, loading Pd NPs onto (Hf)MOL-Ru-PEI could not only improve the electron transfer ability of (Hf)MOL-Ru-PEI, but also provide more active sites for the reaction of Ru(dcbpy)32+ and PEI. In the presence of CEA, CuFe2O4@PDA-MB-Ab2 efficiently quenches the excited states of (Hf)MOL-Ru-PEI-Pd by PDA, Cu2+, and methylene blue (MB) via energy and electron transfer, leading to an ECL signal decrease. Under optimal conditions, the proposed CEA sensing strategy showed satisfactory properties ranging from 0.1 pg mL-1 to 100 ng mL-1 with a detection limit of 20 fg mL-1. SIGNIFICANCE: The (Hf)MOL-Ru-PEI-Pd and CuFe2O4@PDA-MB were prepared in this work might open up innovative directions to synthesize luminescence-functionalized MOLs and effective quencher. Besides, the ECL quenching mechanism of Ru(dcbpy)32+ by MB was successfully explained by the inner filter effect (ECL-IFE). At last, the proposed immunosensor exhibits excellent repeatability, stability, and selectivity, and may provide an attractive way for CEA and other disease markers determination.

N-doped TiO2/Ti3C2-driven self-photocatalytic molecularly imprinted ECL sensor for sensitive and steady detection of dexamethasone.

The conventional luminol-based electrochemiluminescence (ECL) biosensor suffers from hampered signal stability due to the self-decomposition of the H2O2 co-reactant. Here, we propose an N-doped TiO2/Ti3C2 heterojunction driven self-photocatalytic platform for ECL signal amplification and then combine it with molecular imprinting technology for sensitive and steady detection of dexamethasone (DXM). Unlike traditional cases involving specific catalysts or external electron injection, the initial luminescence of luminol in this new system is utilized as the excitation light of N-doped TiO2/Ti3C2 photocatalyst to promote the conversation of dissolved oxygen to H2O2, supplying more co-reactants to improve ECL of luminol in turn. Thanks to the heterojunction and self-photocatalytic cyclic amplification, this molecularly imprinted ECL sensor exhibits a wide linear range (1.0 × 10-6-1.0 × 101 µg mL-1) and a low detection limit, as well as excellent anti-interference capability, sensitivity, and stability. This work contributes to more reliable and steady detection of DXM and brings new insights into developing exogenous co-reactant-free self-enhancement ECL models for biosensor applications.

Molecular imprinting-based Ru@SiO2-embedded covalent organic frameworks composite for electrochemiluminescence detection of cyanidin-3-O-glucoside.

Cyanidin-3-O-glucoside (C3G), a natural antioxidant, plays multiple physiological or pathological roles in maintaining human health; thereby, designing advanced sensors to achieve specific recognition and high-sensitivity detection of C3G is significant. Herein, an imprinted-type electrochemiluminescence (ECL) sensing platform was developed using core-shell Ru@SiO2-CMIPs, which were prepared by covalent organic framework (COF)-based molecularly imprinted polymers (CMIPs) embedded in luminescent Ru@SiO2 cores. The C3G-imprinted COF shell not only helps generate a steady-enhanced ECL signal, but also enables specific recognition of C3G. When C3G is bound to Ru@SiO2-CMIPs with abundant imprinted cavities, resonance energy transfer (RET) behavior is triggered, resulting in a quenched ECL response. The constructed Ru@SiO2-CMIPs nanoprobes exhibit ultra-high sensitivity, absolute specificity, and an ultra-low detection limit (0.15 pg mL-1) for analyzing C3G in food matrices. This study provides a means to construct an efficient and reliable molecular imprinting-based ECL sensor for food analysis.

A novel "on-off-on" electrochemiluminescence strategy based on RNA cleavage propelled signal amplification and resonance energy transfer for Pb2+ detection.

BACKGROUND: Lead (Pb) is one of the most toxic heavy-metal pollutants. Additionally, lead ions (Pb2+) can accumulate in the human body through the food chain, causing irreversible damage through organ damage and system disorders. In the past few years, the detection of Pb2+ has mainly relied on instrumental methods such as atomic absorption spectroscopy (AAS) and inductively coupled plasma mass spectrometry (ICP-MS). Nonetheless, these techniques are complicated in terms of equipment and procedures, along with being time-intensive and expensive in terms of detection. These drawbacks have limited their wide application. Hence, there is a pressing need to develop detection techniques for Pb2+ that are not only cost-efficient but also highly sensitive and specific. RESULTS: A novel "on-off-on" electrochemiluminescence (ECL) sensor for detecting Pb2+ was developed based on the resonance energy transfer (RET) effect between AuNPs and boron nitride quantum dots (BN QDs) and the recognition of Pb2+ by DNAzyme along with the cleavage reaction of the substrate chain. Poly(6-carboxyindole)/stannic sulfide (P6ICA/SnS2) nanocomposite was employed as a co-reaction accelerator to consequently facilitate the production of intermediate SO4•-. This effective enhancement of the reaction led to an improved ECL intensity of BN QDs and enabled the sensor platform to exhibit a higher original ECL response. Benefiting from the combination of the DNAzyme signal amplification strategy with the "on-off-on" design, the ECL sensor showed satisfactory selectivity, good stability, and high sensitivity. This ECL sensor exhibited a linear detection range (LDR) of 10-12-10-5 M and a limit of detection (LOD) of 2.6 × 10-13 M. SIGNIFICANCE: In the present work, an "on-off-on" ECL sensor is constructed based on RET effect for ultrasensitive detection of Pb2+. P6ICA/SnS2 was investigated as the co-reaction accelerator in this sensor. Moreover, this ECL sensor exhibited excellent analytical capability for detecting Pb2+ in actual water samples, providing a method for detecting other heavy metal ions as well.

A molecularly imprinted sensor for single-molecule detection of pesticide metabolite at the amol/L level sensitized by water-soluble luminol derivative encapsulated liposome via click reaction.

A novel luminol derivative, 4-[(1,4-dioxo-1,2,3,4-tetrahydrophthalazin-5-yl)amino]-4-oxobut-2-enoic acid (ALD) with electrochemiluminescence intensity and stability characteristics similar to luminol, but higher solubility in near neutral solution, was designed and synthesized in this study. Using this derivative, a molecular imprinted electrochemiluminescence sensor (MIECLS) was prepared for the sensitive and selective determination of 2-amino-5-mercapto-1,3,4-thiadiazole (AMT), a metabolite of bismerthiazol, thiediazole copper, thiazole zinc, and other pesticides. The ALD probes encapsulated in liposomes are immobilized on the molecularly imprinted film by light-triggered click reaction, and the concurrent release of multiple probes allows for highly sensitive detection. In the AMT concentration range of 1.00 × 10-18 - 5.00 × 10-13 mol/L, the relation between ECL response and log AMT concentration is linear. With a detection limit of 5.25 × 10-19 mol/L (about 4 - 6 molecules in 10 µL of the sample), the sensor allows for high sensitivity analysis of ultra-trace amounts of small organic compounds. In general, the ECL-based single-molecule detection technique proposed herein might be a promising alternative to fluorescence single-molecule detection.

High-performance electrochemiluminescence sensors based on ultra-stable perovskite quantum dots@ZIF-8 composites for aflatoxin B1 monitoring in corn samples.

Aflatoxin B1 (AFB1) that is prone to contaminate corns brings a serious threat to human health. Therefore, it is of great significance to construct novel detection methods for AFB1 tracing. Here, methylamine perovskite quantum dots (MP QDs) encapsulated by ZIF-8 metal-organic frameworks (MP QDs@ZIF-8) were prepared and then ultra-stable electrochemiluminescence (ECL) sensors were developed. By the confinement of cavities structure, multiple MP QDs were crystallized and embedded inside ZIF-8 to form MP QDs@ZIF-8, achieving stable and robust ECL responds in aqueous environment. Further combined with AFB1-imprinted polymer, the constructed ECL sensor showed good selectivity and ultra-sensitivity (the detection limit was 3.5 fg/mL, S/N = 3) with a wide linear range from 11.55 fg/mL to 20 ng/mL for AFB1 quantification. Satisfactory recoveries in corn samples indicated the reliable practicability of the proposed sensor for AFB1 assay. This work provided a novel pathway in designing high-performance ECL sensing platform for food safety.

Ultrasensitive electrochemiluminescence sensor based on perovskite quantum dots coated with molecularly imprinted polymer for prometryn determination.

A highly effective molecularly imprinted electrochemiluminescence sensor was constructed for prometryn determination in environmental and biological samples by using perovskite quantum dots coated with a molecularly imprinted silica layer (MIP/CsPbBr3-QDs) as the recognition and response element. MIP/CsPbBr3-QDs were immobilized on a glassy carbon electrode (GCE) through electropolymerization, and the electrochemiluminescence (ECL) response of MIP/CsPbBr3-QDs could be motivated under the condition of H2O2 as co-reactant. ECL signal was selectively quenched with prometryn by hindering electron transfer and directly proportional to the logarithm of prometryn concentration (0.10-500.0 µg/L) with a correlation coefficient of 0.9960. Limits of detection in fish and seawater samples were 0.010 µg/kg and 0.050 µg/L, respectively. Excellent recoveries of 88.0%-106.0% were acquired for fish and seawater samples with a relative standard deviation below 4.2%. The constructed MIECL sensor based on MIP/CsPbBr3-QDs showed good stability, accuracy, and precision for sensitive detection of prometryn in aquaculture products and environmental samples.

Highly selective molecularly imprinted-electrochemiluminescence sensor based on perovskite/Ru(bpy)32+ for simazine detection in aquatic products.

A novel molecularly imprinted electrochemiluminescence (MIECL) sensor based on the luminescence of molecularly imprinted polymer-perovskite (MIP-CsPbBr3) layer and Ru(bpy)32+ was fabricated for simazine detection. MIP-CsPbBr3 layers were immobilized onto the surface of glassy carbon electrode as the capture and signal amplification probe, and Ru(bpy)32+ and co-reactant tripropylamine exhibited stronger electrochemiluminescence (ECL) emission. Under optimal conditions, the ECL signal of the MIECL sensor was linearly quenched, with the logarithm of simazine concentration ranging from 0.1 µg/L to 500.0 µg/L, correlation coefficient of 0.9947, and limit of detection of 0.06 µg/L. The practicality of the developed MIECL sensor method for simazine determination in aquatic samples was validated. Excellent recoveries of 86.5 %-103.9 % with relative standard deviation below 1.6 % were obtained for fish and shrimp samples at three different spiked concentrations. The MIECL sensor exhibited excellent selectivity, sensitivity, reproducibility, accuracy, and precision for simazine determination in actual aquatic samples.

A Flexible Electrochemiluminescence Sensor Equipped With Vertically Ordered Mesoporous Silica Nanochannel Film for Sensitive Detection of Clindamycin.

Fast, convenient, and highly sensitive detection of antibiotic is essential to avoid its overuse and the possible harm. Owing to enrichment effect and antifouling ability of ultrasmall nanochannels, the vertically ordered mesoporous silica nanochannel film (VMSF) has great potential in the development of the facile electrochemiluminescence (ECL) sensor for direct and sensitive analysis of antibiotics in complex samples. In this study, we demonstrated a flexible ECL sensor based on a cost-effective electrode covered with a VMSF for sensitive detection of clindamycin. Polyethylene terephthalate coated with indium tin oxide (PET-ITO) is applied as a flexible electrode to grow VMSF using the electrochemically assisted self-assembly (EASA) method. The negatively charged VMSF nanochannels exhibit significant enrichment toward the commonly used cationic ECL luminophores, tris(2,2-bipyridyl) dichlororuthenium (II) (Ru (bpy)3 2+). Using the enhanced ECL of Ru (bpy)3 2+ by clindamycin, the developed VMSF/PET-ITO sensor can sensitively detect clindamycin. The responses were linear in the concentration range of 10 nM-25 µM and in the concentration range of 25-70 µM. Owing to the nanoscale thickness of the VMSF and the high coupling stability with the electrode substrate, the developed flexible VMSF/PET-ITO sensor exhibits high signal stability during the continuous bending process. Considering high antifouling characteristic of the VMSF, direct analysis of clindamycin in a real biological sample, human serum, is realized.

A "signal on/off" biomimetic electrochemiluminescence sensor using titanium carbide nanodots as co-reaction accelerator for ultra-sensitive detection of ciprofloxacin.

It is of great significance to explore an efficient and sensitive method for the detection of ciprofloxacin (CIP) for the protection of human health and ecological environment. In this study, a novel molecularly imprinted electrochemiluminescence sensor (MIECLS) was constructed using amino-functional titanium carbide nanodots (TNDs) as co-reactant accelerator in the cathodic electrochemiluminescence system. With K2S2O8 as co-reactant, the obvious cathode luminescence signal of carbon nitride nanosheets (CNNS) can be observed under the synergistic effect of TNDs. TNDs not only advanced the conductivity of CNNS, and the presence of amino group accelerated the reduction of the co-reactant S2O82-, which generated a rich ECL reaction intermediate SO4-• near CNNS, thus greatly enhancing the ECL signal of CNNS. In addition, the proposed MIECLS have good anti-interference, high sensitivity and selectivity by electropolymerization of o-phenylenediamine as functional monomer to form molecularly imprinted polymer (MIP) with specific recognition sites on electrode surface. The MIECLS was applied for determination of CIP, and its ECL intensity was linearly quenched with the increasing concentration of CIP from 5 × 10-9 to 5 × 10-6 mol L-1 with a detection limit of 1.20 × 10-9 mol L-1 (S/N = 3). Futhermore, in the actual sample analysis, the detection results of MIECLS showed good consistency with those of HPLC, indicating that MIECLS has a broad application prospect in the rapid and sensitive analysis of CIP in food samples.

Encapsulating Ru(bpy)32+ in an infinite coordination polymer network: Towards a solid-state electrochemiluminescence sensing platform for histamine to evaluate fish product quality.

In this work, we demonstrate a novel solid-state electrochemiluminescence (ECL) sensor based on the Ru(bpy)32+@terbium-guanosine monophosphate infinite coordination polymer network ((Ru(bpy)32+@Tb-GMP ICPn). Comparing with the traditional luminescence of Ru(bpy)32+ observed in a liquid system, the proposed method of encapsulating Ru(bpy)32+ into ICPn for immobilization greatly improves the ECL signal and efficiency, which is attributed to the unique porous structure and large specific surface area of ICPn. Moreover, the solid-state Ru(bpy)32+ ECL sensor has good biocompatibility and low toxicity. Taking histamine (HA) as a detection model, a good linear relationship between ECL intensity and logarithm of HA concentration was obtained with a low detection limit of 17 nM, and satisfactory results were obtained for detecting HA levels in fish samples as well. The proposed solid-state Ru(bpy)32+ ECL sensor has great application prospects in the safety of food.

Biomimetic Synthesis of Ultrafine Mixed-Valence Metal-Organic Framework Nanowires and Their Application in Electrochemiluminescence Sensing.

Metal-organic frameworks (MOFs) prepared via typical procedures tend to exhibit issues like poor water stability and poor conductivity, which hinder their application in electrochemical sensing. Herein, we report a strategy for the preparation of mixed-valence ultrafine one-dimensional Ce-MOF nanowires based on a micelle-assisted biomimetic route and subsequent investigation into their growth mechanism. The prepared mixed-valence Ce-MOF nanowires exhibited a typical size of ∼50 nm and were found to present good water stability and high conductivity. On this basis, we examined the introduction of these nanowires into the luminol hydrogen peroxide luminescence system and proposed a novel dual-route self-circulating electrochemiluminescence (ECL) catalytic amplification mechanism. Finally, in combination with molecular imprinting, a MOF-based ECL sensor was developed for the detection of trace amounts of imidacloprid in plant-derived foods. This sensor exhibited a linearity of 2-120 nM and a detection limit of 0.34 nM. Thus, we proposed not only a novel route to MOF downsizing but also a facile and robust methodology for the design of a MOF-based molecular imprinting ECL sensor.

Ultrasensitive electrochemiluminescence sensor based on nitrogen-decorated carbon dots for Listeria monocytogenes determination using a screen-printed carbon electrode.

Current method for identification of foodborne pathogens suffers from its relatively poor performance, consequently limiting its use. Herein, we first describe an ultrasensitive electrochemiluminescence (ECL) sensor based on nitrogen-decorated carbon dots (NCDs) for Listeria monocytogenes (L. monocytogenes) determination using a screen-printed carbon electrode (SPCE). Citric acid serves as carbon source, and ethylenediamine, a molecule containing nitrogen atom, is employed to synthesize CDs. Approximately 4 nm NCD with homogenous size distribution can be produced via a single step green microwave-assisted methodology. The construction of ECL sensor is initiated by the immobilization of capture antibody (Ab1) onto the carboxyl graphene (GOOH)-modified SPCE, where immunocomplexes (antigen and the NCD-labelled secondary antibody (Ab2-NCD)) are formed, resulting in a substantial increment in the ECL signal response in the presence of K2S2O8. The GOOH allows direct formation of the capture antibodies and enhances the electrochemical properties. Under optimal parameters, this sensor exhibits wide linearity (2 to 1.0 × 106 CFU mL-1), high sensitivity (0.104 or 1.0 × 10-1 CFU mL-1) and specificity over the nontargeting studied pathogens and is successfully applied to determine L. monocytogenes in food products. These promising results together with its performance suggest that this proposed platform may serve as an alternative device to effectively control the spread of foodborne diseases.