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.

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.

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.

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 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.

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.

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.

Nickel nanoclusters as a novel emitter for molecularly imprinted electrochemiluminescence based sensor toward nanomolar detection of creatinine.

In this study nickel nanoclusters (NiNCs), was promised as novel and economic electrochemiluminescence (ECL) emitter for highly sensitive and selective determination of creatinine in the presence of molecularly imprinted polymer (MIP). The uniform magnetic graphene oxide (GO-Fe3O4) MIP film was established on the surface of ITO electrode and Ni NCs-embedded in MIP, showed a strong anodic ECL emission using tri-n-propylamine (TPrA) as coreactant. During the ECL process, TPrA was oxidized, and Ni NCs got the energy to generate excited state Ni NCs* for light emission. When the imprinted cavities were occupied by creatinine, the ECL emission of Ni NCs on the MIP-modified electrode surface was efficiently quenched. Under optimal conditions, the proposed sensor demonstrated ultrasensitive and accurate analytical performance toward creatinine detection with a linear range from 5 nM to 1 mM and detection limit of 0.5 nM (S/N = 3). The biosensor showed good specificity for creatinine determination compared to other compounds that having the chemical structure analogue or close to the template creatinine, when the concentration ratio of interference to creatinine was more than 100 times. Furthermore, the biosensor was successfully applied to determination of creatinine in human serum and urine samples with satisfactory results. So, this assay for creatinine detection possesses high sensitivity, good selectivity, excellent reproducibility and stability. We expect the combination of molecular imprinting system with ECL assay in the presence of Ni NCs as a new type of superior luminophore candidate can be developed for design of ultrasensitive sensors, biosensors and other measuring devices.

An electrochemiluminescence sensor for bromate assay based on a new cationic polythiophene derivative.

A sensitive electrochemiluminescence (ECL) sensor was fabricated for bromate assay based on a cationic polythiophene derivative, poly[3-(1,1'-dimethyl-4-piperidinemethylene)thiophene-2,5-diyl chloride] (PTh-D)/nafion modified Au electrode. Bromate was used as the coreactant as well as detecting analyte in the ECL sensor for the first time. The prepared PTh-D exhibited excellent solubility, strong and stable cathodic ECL activity. PTh-D can be immobilized on the surface of Au electrode via AuS bonding and nafion and chitosan were also used to immobilize PTh-D. The fabricated sensor exhibited a good linear relationship between the ECL intensities and the concentrations of BrO3(-) ranging from 1 µM to 0.1 M with a detection limit of 1 µM. This proposed method not only expands the application of PTh-D, but also opens new doors toward the detection of BrO3(-).

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.