CeO2 quantum dots modified electrode for detecting hydrogen peroxide

Glutathione-Capped CdTe Quantum Dots Based Sensors for Detection of H2O2 and Enrofloxacin in Foods Samples

Additives and antibiotic abuse during food production and processing are among the key factors affecting food safety. The efficient and rapid detection of hazardous substances in food is of crucial relevance to ensure food safety. In this study, a water-soluble quantum dot with glutathione as a ligand was synthesized as a fluorescent probe by hydrothermal method to achieve the detection and analysis of H₂O₂. The detection limits were 0.61 μM in water and 68 μM in milk. Meanwhile, it was used as a fluorescent donor probe and manganese dioxide nanosheets were used as a fluorescent acceptor probe in combination with an immunoassay platform to achieve the rapid detection and analysis of enrofloxacin (ENR) in a variety of foods with detection limits of 0.05-0.25 ng/mL in foods. The proposed systems provided new ideas for the construction of fluorescence sensors with high sensitivity.

Electrochemical sensor for the non-enzymatic reduction of hydrogen peroxide and oxidation of gallic acid using a polyamidoblack-10B (PAB)-modified electrode

A novel electrochemical sensor for the oxidation of gallic acid and reduction of hydrogen peroxide using a paraffin impregnated graphite electrode modified with polyamidoblack 10B is developed.

Polymer scaffold layers of screen-printed electrodes for homogeneous deposition of silver nanoparticles: application to the amperometric detection of hydrogen peroxide

A method is described for electrochemical oxidation of polymers on the surface of screen-printed electrodes (SPCE). These act as scaffold layers for homogeneous deposition of silver nanoparticles (AgNPs). Hexamethylenediamine (HMDA) and poly(ethylene glycol) were immobilized on the SPCE surface via electrochemical oxidation. AgNPs were then electrodeposited on the scaffolds on the SPCE. This type of different carbon chain containing materials like PEG and HMDA act as big tunnels for electron mobility and are useful for the homogenous deposition of AgNPs on the SPCE surface without agglomeration. The resulting sensor was applied to the determination of hydrogen peroxide (H₂O₂) as a model analyte. It is found to display favorable catalytic and conductive properties towards the reduction of H₂O₂. Cyclic voltammetry and amperometry revealed that the modified electrode performs better than other modified SPCEs. Best operated at a potential of around -0.61 V (vs Ag|AgCl), the amperometric response is linear in the 10-180 μM H₂O₂ concentration range and the detection limit is 1.5 μM. The sensor is stable and reproducible. The resultant sensor was appplied to toothpaste analysis, and good recovery values were gained. Graphical abstractSchematic representation of electropolymerization of poly(ethylene glycol) and hexamethylenediamine scaffold layers on screen-printed electrodes for homogeneous electrodeposition of silver nanoparticles. This electrode was applied for the amperometric determination of hydrogen peroxide.

Development of Ratiometric Fluorescence Sensors Based on CdSe/ZnS Quantum Dots for the Detection of Hydrogen Peroxide

In this study, carboxyl group functionalized-CdSe/ZnS quantum dots (QDs) and aminofluorescein (AF)-encapsulated polymer particles were synthesized and immobilized to a sol-gel mixture of glycidoxypropyl trimethoxysilane (GPTMS) and aminopropyl trimethoxysilane (APTMS) for the fabrication of a hydrogen peroxide-sensing membrane. CdSe/ZnS QDs were used for the redox reaction of hydrogen peroxide (H2O2) via a reductive pathway by transferring electrons to the acceptor that led to fluorescence quenching of QDs, while AF was used as a reference dye. Herein, the ratiometric fluorescence intensity of CdSe/ZnS QDs and AF was proportional to the concentration of hydrogen peroxide. The fluorescence membrane (i.e., QD-AF membrane) could detect hydrogen peroxide in linear detection ranges from 0.1 to 1.0 mM with a detection limit (LOD) of 0.016 mM and from 1.0 to 10 mM with an LOD of 0.058 mM. The sensitivity of the QD-AF membrane was increased by immobilizing horseradish peroxidase (HRP) over the surface of the QD-AF membrane (i.e., HRP-QD-AF membrane). The HRP-QD-AF membrane had an LOD of 0.011 mM for 0.1-1 mM H2O2 and an LOD of 0.068 mM for 1-10 mM H2O2. It showed higher sensitivity than the QD-AF membrane only, although both membranes had good selectivity. The HRP-QD-AF membrane could be applied to determine the concentration of hydrogen peroxide in wastewater, while the QD-AF membrane could be employed for the detection of α-ketobutyrate.