Determination of Trace Phosphoprotein in Food Based on Fluorescent Probe-Triggered Target-Induced Quench by Electrochemiluminescence

Electrochemiluminescence sensor based on upconversion nanoparticles and Zr-based porphyrinic metal-organic frameworks with recognition sites for mercaptan detection

In light of the critical necessity for precise detection of mercaptan in gasoline, due to its potential to induce metal corrosion and catalyst poisoning, this study investigates a novel methodology that employs resonance energy transfer (RET) between upconversion nanoparticles (UCNPs) and zirconium-based porphyrinic metal-organic frameworks (MOFs) to develop a highly sensitive and selective electrochemiluminescence (ECL) sensor. The NaYF4: Yb3+, Er3+@NaYF4@MOFs nanocomposite has been thoroughly characterized and exhibits enhanced ECL emission. This enhancement is attributed to the efficient RET between the UV-vis absorption of the Zr-based porphyrinic MOFs and the upconversion luminescence emission of the UCNPs. Upon interaction with mercaptan, the ECL signal experiences a significant decrease due to the interaction between mercaptan and Zr-based porphyrinic MOFs, leading to the quenching of the ECL signal. This phenomenon facilitates the sensitive detection of mercaptan within a linear range of 0.5 mg/L to 200 mg/L, with a low detection limit of 0.054 mg/L. The sensor demonstrates high selectivity and excellent stability, making it a promising tool for the quality control and environmental monitoring of mercaptan in gasoline.

Rapid determination for tyrosine isomers in food based on N-acetyl-L-cysteine/Upconversion nanomaterials target-induced quench by chiral Electrochemiluminescence sensor

Rapid determination of amino acid isomer is very important for the evaluation of the amino acid nutrition in different foods, so a fast and sensitive electrochemiluminescence (ECL) sensor was innovatively fabricated for the determination of tyrosine isomers in foods based on N-Acetyl-L-cysteine/upconversion nanomaterials possessed a good particular selectivity to L-tyrosine. Under the optimal conditions, for L-tyrosine, the limit of detection (LOD) of the sensor for L-tyrosine was 2.87 × 10-6 M, detection range of 5.5 × 10-5-5.5 × 10-3 M, for D-tyrosine, LOD was 2.56 × 10-5 M, detection range was from 5.5 × 10-4 to 5.5 × 10-3 M. The developed chiral sensor was used to determinate the tyrosine isomers in foods successfully, which provided a convenient method to quickly evaluate the nutritional value of amino acids in food.

An electrochemical sensor for the rapid detection of zearalenone based on the mimic peptide screened by molecular simulation

An electrochemical sensor was developed for detecting zearalenone (ZEN) based on the mimic peptide, which was screened from the library and validated by molecular simulation and electrochemical methods. The library of the mimic peptide was constructed according to the structural analysis, molecular docking, molecular dynamics and amino acid mutation. Then, the enhanced electrical signal was attributed to gold nanoparticles (AuNPs) and reduced carboxylated graphene oxide (rGO-COOH). Under the optimal conditions, the detection limit was 0.91 pg·mL-1 (S/N = 3) with a wide linear range from 0.01 ng·mL-1 to 10 ng·mL-1. In grain samples, a good recovery rate of 84% to 105.3% was achieved, while the rate ranged from 82% to 108.8% in the commercial ELISA kits. Additionally, the electrochemical sensor exhibited the remarkable specificity, excellent stability and better reproducibility (RSD = 1.94%). This sensor has great potential for rapidly detecting ZEN in food.

Supersensitive detection of lincomycin with an ECL aptasensor based on the synergistic integration of gold-functionalized upconversion nanoparticles and thiolated 3,4,9,10-perylene tetracarboxylic acid

In this work, the supersensitive and selective determination of lincomycin (Lin) was achieved using a novel electroluminescent (ECL) aptasensor based on the synergistic integration of gold functionalized upconversion nanoparticles (UCNPs) and thiolated 3,4,9,10-perylene tetracarboxylic acid (PTCA). The integration of two luminophores of UCNPs and PTCA combined the merits of the cathodoluminescence stability of UCNPs and the high quantum yield of PTCA, which significantly promoted the ECL signal and analytical performance of the proposed sensor. The introduction of gold nanoparticles in UCNPs can not only improve the conductivity and ECL performance of UCNPs but also cause them to easily integrate with thiolated PTCA (t-PTCA) via an Au-S bond. The ECL signal of UCNPs@Au/t-PTCA/GCE was almost twice as strong as that of t-PTCA/GCE and tenfold higher than that of UCNPs@Au/GCE. Because of the non-conductive protein of the Lin aptamer, the ECL intensity of apt/UCNPs@Au/t-PTCA/GCE noticeably decreased. In the presence of Lin, the aptamer was pulled down from the sensing interface, resulting in the recovery of the ECL intensity of the sensor. Under optimal conditions, our proposed sensor can quantify the concentration of Lin in the range from 1.0 × 10-15 to 1.0 × 10-7 M with a low detection limit of 2.4 × 10-16 M (S/N = 3), exhibiting high sensitivity and specificity for the determination of Lin.

Antenna effect of perylene-sensitized up-conversion luminescent material amplifies the signal of electrochemiluminescence biosensor platform for the ultra-sensitive detection of enrofloxacin

Recently, up-conversion luminescent (UCL) materials have caught extensive sight on account of their excellent biocompatibility and weak automatic fluorescence background, but the low optical signal makes researchers shy away. Organic dye-sensitized UCL materials can improve the low optical signal drawback of UCL and rejuvenate it with adjustable optical properties and unique antenna effects. In this work, an efficient, simple and selective electrochemiluminescence (ECL) sensing platform was developed for determination of enrofloxacin (ENR). 3,4,9,10-perylene tetracarboxylic acid (PTCA) was successfully used as an "antenna" to improve the ECL performance of the UCL nanoparticles (PEI-NaYF4: Yb, Er) due to its appropriate excitation spectrum position and superior electron transfer rate. The specific recognition function of the aptamer enabled the sensor to eliminate the interference from conspecific impurity. In the presence of ENR, the specific combination of ENR with aptamer made the aptamer fall from surface of the electrode, thus we could see a considerable enhancement of signal. Under the most favourable conditions, the aptasensor based on antenna effect displayed a wide detection range (1.0 × 10-14∼1.0 × 10-6 M), low limit of detection (LOD = 3.0 × 10-15 M) and receivable recoveries (96.0%-102.4%) during water samples analysis. At this point, antenna effect provides a powerful strategy to expand the application of UCL in the field of ECL biosensing.

Aptamer recognition-promoted specific intercalation of iridium complexes in G-quadruplex DNA for label-free and enzyme-free phosphorescence analysis of kanamycin

In consideration of relevance of antibiotic with food security, it is extremely desirable to propose sensitive and credible methods for antibiotic screening. Nevertheless, most of known approaches are developed based on fluorescence technique, which suffered from the interferences of background fluorescence and autoluminescence, and tedious labeling procedures, ascribing to the deficiency of high-performance and multifunctional dyes. Herein, we developed a novel iridium (III) complex (Ir-QAU)-based aptamer-promoted phosphorescence sensor for label-free, enzyme-free and highly sensitive detection of target antibiotic (kanamycin, Kan) based on target-switched hybridizing chain reaction (HCR). Ir-QAU was elaborately devised to present a signal-on response to G-quadruplex (G4) DNA against other DNAs due to its specific intercalation in G4 DNA and subsequent restriction of intra-molecular rotation. The recognition of H1 by Kan promoted the formation of Kan@H1 complexes, which hybridized with H2 and H3 via toehold-mediated hybridization reaction, subsequently switching HCR to produce large numbers of G4 DNA. Compared to Kan absence, abundant Ir-QAU was locked in G4 DNA to yield a significantly increased luminescence, which switches the luminescence analysis process of Kan with a limit of detection down to 0.38 pM. Furthermore, the Ir-QAU-based sensor was triumphantly applied to detect Kan in milk sample. We anticipate this work will disclose a new way to development of high-efficiency and practical luminescence sensor, and show a great potential for antibiotic-related food security.

In Situ Growth Intercalation Structure MXene@Anatase/Rutile TiO2 Ternary Heterojunction with Excellent Phosphoprotein Detection in Sweat

Abnormal protein phosphorylation may relate to diseases such as Alzheimer's, schizophrenia, and Parkinson's. Therefore, the real-time detection of phosphoproteins in sweat was of great significance for the early knowledge, detection, and treatment of neurological diseases. In this work, anatase/rutile TiO₂ was in situ grown on the MXene surface to constructing the intercalation structure MXene@anatase/rutile TiO₂ ternary heterostructure as a sensing platform for detecting phosphoprotein in sweat. Here, the intercalation structure of MXene acted as electron and diffusion channels for phosphoproteins. The in situ grown anatase/rutile TiO₂ with n-n-type heterostructure provided specific adsorption sites for the phosphoproteins. The determination of phosphoprotein covered concentrations in sweat, with linear range from 0.01 to 1 mg/mL, along with a low LOD of 1.52 μM. It is worth noting that, since the macromolecular phosphoprotein was adsorbed on the surface of the material, the electrochemical signal gradually decreased with the increase of phosphoprotein concentration. In addition, the active sites in the MXene@anatase/rutile TiO₂ ternary heterojunction and synergistic effect of the heterojunction were verified by first-principle calculations to further realize the response to phosphoproteins. Additionally, the effective diffusion capacity and mobility of phosphoprotein molecules in the ternary heterojunction structure were studied by molecular dynamics simulation. Furthermore, the constructed sensing platform showed high selectivity, repeatability, reproducibility, and stability, and this newly developed sensor can detect for phosphoprotein in actual sweat samples. This satisfactory sensing strategy could be promoted to realize the noninvasive and continuous detection of sweat.

Biofuel Cell-Driven Robust Electrochemiluminescence Biosensing Platform

Electrochemiluminescence (ECL) is one powerful tool in the sensing field, in which the electrochemical workstation is necessary to achieve the electrical/optical signal conversion in the presence of luminescent agents. By contrast, biofuel cells (BFCs) can also provide electricity from renewable biofuels under moderate conditions. More importantly, BFCs with the features of adjustable voltage output and excellent compatibility would well meet the requirement of working voltages for different ECL devices. However, to the best of our knowledge, the BFC-driven luminous system has not been reported. In this work, we constructed, for the first time, a BFC-driven ECL system with fast and stable signal outputs. To demonstrate the proof-of-concept of the BFC-ECL system, the sensitive and selective detection of histidine was achieved, exhibiting great potential among point-of-care diagnoses in remote regions. Overall, this work not only paves a new way for the conversion of chemical energy, electrical energy, and luminous system but also explores the new application of BFC.

Dual-signal electrochemiluminescence immunosensor for Neuron-specific enolase detection based on "dual-potential" emitter Ru(bpy)32+ functionalized zinc-based metal-organic frameworks

Neuron-specific enolase (NSE) is the preferred marker for monitoring small cell lung cancer and neuroblastoma. We devised a dual-signal ratiometric electrochemiluminescence (ECL) sensing strategy for sensitive detection of NSE. In this work, Ru (bpy)₃²⁺ functionalized zinc-based metal-organic framework (Ru-MOF-5) nanoflowers (NFs) with plentiful carboxyl groups provide an excellent biocompatible sensing platform for the construction of immunosensor. Importantly, Ru-MOF-5 NFs possess stable and efficient "dual-potential" ECL emission of cathode (-1.5 V) and anode (1.5 V) in the existence of co-reactant K₂S₂O₈. Simultaneously, the cathode ECL emitter ZnO-AgNPs are employed as the secondary antibody marker, whose participation amplify the cathode ECL signal as well attenuate the anode ECL emission of Ru-MOF-5 NFs. By monitoring the ECL dual-signal of -1.5 V and 1.5 V and calculating their ratios, a ratiometric strategy of quantified readout proportional is implemented for the proposed immunosensor to precise analyze NSE. Based on optimization conditions, the ECL immunosensor displays the wide linear range of 0.0001 ng/mL to 200 ng/mL and the minimum detection limit is 0.041 pg/mL. The "dual-potential" ratiometric ECL immunosensor effectively reduces system error or background signal by self-calibration from both emissions and improves detection reliability. The dual-signal ratiometric strategy with satisfactory reproducibility and stability provides further development possibilities for other biomolecular detection and analysis.