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A two-step resonance energy transfer (RET)-based fluorescence/electrochemiluminescence (FL/ECL) biosensor was developed for ratiometric measurement and annihilation of Staphylococcus aureus (S. aureus). Using coupled dual-recognition-triggered target conversion with the catalytic hairpin assembly (CHA) technique, the monitoring of S. aureus was obtained at the single-cell level. [ABSTRACT FROM AUTHOR]

Fumonisin B1 (FB1) is a toxin produced by the metabolism of Fusarium oxysporum, which can cause serious effects on the nervous, respiratory, digestive, and reproductive systems of humans or animals; it is known as one of the highly toxic epidemic contaminants. Herein, we report the visual inspection of FB1 using bipolar electrodes (BPEs) with an array-based electrochemiluminescence (ECL) platform. The sensor consists of a PDMS cover and a glass substrate containing an array of 10 ITO electrodes. A specific sensing interface was constructed on the cathode of the BPE, which could modulate the ECL reactions that occurred at the anode of BPEs. To amplify the ECL signal, methylene blue (MB)-encapsulated Zr-MOFs (MB@Zr-MOFs) were synthesized and immobilized on the cathode of the BPE, which could amplify the ECL signal at the anode. By coupling the cyclic amplification effect of the DNA walker and nicking endonuclease (Nb.BbvCI), the biosensor can realize the visual measurement of FB1 in the range of 5 × 10−5~0.5 ng/mL. In addition, the developed biosensor was used to monitor the concentration of FB1 in maize and peanut samples. The recoveries were in the range of 99.2%~110.6%, which demonstrated the good accuracy of the designed BPE-ECL biosensor for FB1 assay in food samples. [ABSTRACT FROM AUTHOR]

Rapid and efficient detection of mycotoxins is of great significance in the field of food safety. In this review, several traditional and commercial detection methods are introduced, such as high-performance liquid chromatography (HPLC), liquid chromatography/mass spectrometry (LC/MS), enzyme-linked immunosorbent assay (ELISA), test strips, etc. Electrochemiluminescence (ECL) biosensors have the advantages of high sensitivity and specificity. The use of ECL biosensors for mycotoxins detection has attracted great attention. According to the recognition mechanisms, ECL biosensors are mainly divided into antibody-based, aptamer-based, and molecular imprinting techniques. In this review, we focus on the recent effects towards the designation of diverse ECL biosensors in mycotoxins assay, mainly including their amplification strategies and working mechanism. [ABSTRACT FROM AUTHOR]

• Novel BPE-ECL biosensor based on DNA network was developed for S. aureus assay. • Synergic amplification effect based on target-triggered PCR and pMB NPs was used. • Three-dimensional Au-DNA network allows for the loading of plenty pMB NPs. • The electrochemical reduction of pMB NPs could greatly amplify the ECL intensity. A novel bipolar electrode (BPE)-electrochemiluminescence (ECL) device was constructed for the ultra-sensitive detection of Staphylococcus aureus (S. aureus) by combining polymerase chain reaction (PCR) amplification and DNA network-loaded polymethylene blue nanoparticles (pMB NPs). The presence of target triggered the dissociation of double-stranded DNA on Fe 3 O 4 NPs and the release of T strand, which initiated the PCR. The PCR product contains two protruding single-stranded DNA fragments that serve as bridges to connect Au NPs labeled probes. The PCR-Au products were captured by the probes on cathode of BPE to form three-dimensional DNA networks, which offer multiple adsorption sites for pMB NPs, leading to the remarkable enhancement of ECL intensity. Under optimal circumstances, a wide linear range from 10 to 108 CFU/mL and a low detection limit of 0.78 CFU/mL were achieved. This research opens new horizons for the application of PCR-based biosensors for the accurate and sensitive measurement of pathogenic bacteria. [ABSTRACT FROM AUTHOR]

Abstract: An electrochemiluminescent (ECL) biosensor based on immobilized uricase has been developed for uric acid detection with luminol as signaler. The uricase has been embedded in polypyrrole (PPy) matrix on platinum electrode during the electropolymerization of pyrrole monomer at potential of 0.80V versus Ag/AgCl. This ECL-based biosensor responds to uric acid due to yielded hydrogen peroxide during its catalytic oxidization by uricase with potassium ferricyanide acted as an electron receptor to promote the enzymatic reaction. The so-generated hydrogen peroxide enhanced the ECL intensity of luminol. The kinetic parameters of enzymatic reaction as maximum reaction rates (V max) and Michaelis–Menten constants (K m) are also evaluated for 1.42×10−3 As−1 and 3.4×10−7 M in the presence of potassium ferricyanide, which were all greatly improved. The resulting biosensor showed excellent analytical performance for determination of uric acid as more than 50 times sensitivity than a bare electrode. It gives a 75pM of detection limit and a relative standard deviation of 4.4% for 6.25×10−9 M uric acid (n =6). This ECL-based biosensor has been successfully applied for determination of uric acid in porphyra and kelp samples. [Copyright &y& Elsevier]

The demand for sensitive, portable, and non-destructive analysis of pathogenic bacteria is of significance in point-of-care diagnosis. Herein, we constructed a smart electrochemiluminescence (ECL) biosensor by integrating a flexible paper-based sensing device and a disposable three-electrode detecting system. Staphylococcus aureus (S. aureus)-responsive cellulose paper was prepared by employing aptamer as recognition element and a probe DNA (probe DNA-GOD) tagged with glucose oxidase (GOD) as a signal amplification unit. The formation of aptamer- S. aureus complex mediated the quantitative release of probe DNA-GOD. The remaining probe DNA-GOD on the paper-based aptasensor was then activated by glucose, which resulted in a significant decrease in ECL signal. To further improve the ECL performance of biosensor, a large number of Ru(bpy) 3 2+ molecules were embedded into porous zinc-based metal-organic frameworks (MOFs) to form Ru(bpy) 3 2+ functionalized MOF nanoflowers (Ru-MOF-5 NFs). Such biosensor enabled accurate, non-destructive, and real-time monitoring of S. aureus -contaminated food samples, opening a new avenue for sensitive recognition of pathogenic bacteria. [Display omitted] • A wearable, disposable and smart paper-based biosensor was developed. • The sensor realized the sensitive, in situ and non-destructive analysis of S. aureus. • The limit of detection from our sensor was better than that of some existing methods. • The practical application in the field of S. aureus -contaminated foods was feasible. [ABSTRACT FROM AUTHOR]

A novel portable and disposable bipolar electrode (BPE)-electrochemiluminescence (ECL) device was fabricated for fumonisin B 1 (FB 1) detection. BPE was fabricated by using MWCNTs and polydimethylsiloxane (PDMS) due to their excellent electrical conductivity and good mechanical stiffness. After the deposition of Au NPs on the cathode of BPE, the ECL signal could be improved 89-fold. Then a specific aptamer-based sensing strategy was constructed by grafting capture DNA on Au surface, followed by hybridizing with aptamer. Meanwhile, an excellent catalyst, Ag NPs was labeled on aptamer to activate oxygen reduction reaction, leading to a 13.8-fold enhancement in ECL signal at the anode of BPE. Under the optimal conditions, the biosensor exhibited a wide linear range of 0.10 pg/mL to 10 ng/mL for FB 1 detection. Meanwhile, it demonstrated satisfactory recoveries for real sample detection with good selectivity, making it to be a convenient and sensitive device for mycotoxin assay. A novel BPE-ECL aptasensor was designed for sensitive detection of FB 1 based on flexible electrode and dual-amplification strategy. [Display omitted] • Novel BPE-ECL device based on MWNTs-PDMS fiber electrode was first constructed. • The novel BPE exhibited good sensitivity and reproducibility for ECL detection. • The synergy of Au NPs and Ag NPs on cathode can greatly improve sensor performance. • The portable biosensor showed high sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

Abstract: An electrochemiluminescent (ECL)-based lactate (LA) biosensor is developed with luminol as signaling species. LA was oxidized under the catalysis of immobilized lactic dehydrogenase (LDH) and pyruvate oxidase (PYOD) with nicotinamide adenine dinucleotide (NAD) as coenzyme. As a result, the reaction yielded the hydrogen peroxide, which enhanced the electrochemiluminescence of luminol, which was acceptable for sensing the LA concentration. The resulting biosensor showed excellent response for lactate. A detection limit of 8.9×10−12 mol/L was obtained with the relative standard deviation (RSD) of 4.13% (C LA 1.34×10−10 mol/L, n =6) and an average recovery of 101.3% for real sweat sample. The research suggests that the ECL-based biosensor was practicable for detecting the LA in sweat samples of athletes during the exercitation for evaluation of exercise degree. [Copyright &y& Elsevier]