A novel electrochemical sensor based on the copper-doped copper oxide nano-particles for the analysis of hydrogen peroxide

New nanosensor fabricated on single nanopore electrode filled with prussian blue and graphene quantum dots coated by polypyrrole for hydrogen peroxide sensing

Hydrogen peroxide (H2O2) is a common oxidant that plays an important role in many biological processes and is also an important medium analysis in various fields. In this work, a new electrochemical nanosensor capable of detecting and quantifying hydrogen peroxide was introduced. This nanosensor was fabricated by electrodepositing prussian blue (PB)/graphene quantum dots (GQDs)/polypyrrole (PPy) on single nanopore electrode etched from single gold nanoelectrode. This prepapred nanosensor exhibits good electrochemical response to hydrogen peroxide with high sensitivity and stability, with a linear response in the 2.0 and 80 μM by using amperometric method and differential pulse voltammetry (DPV) method. The limit of detections are 0.33 μM (S/N = 3) for amperometric method and 0.67 μM (S/N = 3) for differential pulse voltammetry (DPV) method, respectively. This nanosensor can be used for the determination of hydrogen peroxide in human urine, and can serve as a new electrochemical platform to monitor H2O2 release from single living cells due to its small overal dimension and high sensitivity.

Heterostructure of Metal Oxides Integrated on a GCE for Estimation of H2O2 Capacity in Milk and Fruit Juice Samples

High levels of H2O2 in food can lead to oxidative stress. Which has been linked to a number of neurological diseases. Hence, its detection in beverages is essential. However, a complicated structure of the reaction medium of H2O2 makes the detection procedure very difficult. For this reason, sensitive strategic methods are required. In this study, quantification of H2O2 in milk and apple juice has been obtained via the electrochemical sensing platform based on GCE/SiO-CeONPs. Scanning Electron Microscopy (SEM), Cyclic voltammetry(CV), and electron impedance spectroscopy(EIS) were employed to characterize the composite. The kinetics investigation of the sensor with H2O2 revealed an a quasi-reversible one -electron adsorption process. Under optimized conditions, the Differential Pulse Voltammetry (DPV) in 0.1 M Phosphate buffer (PB) pH 5.5 of the H2O2 displayed a peak at 0.13 V vs. Ag/AgCl with the detection limits of 0.0004 µM, linearity range of 0.01–0.08 µM. The observed LOD values of this method for real samples were calculated to be 0.006 µM and 0.007 µM with LOQ of 0.02 µM for milk and apple juice, respectively. The recovery of the analyte was from 92 to 99%. Furthermore, due to good selectivity and stability, the benefit of this sensor is its applicability in multiple fields.

Double signal ratiometric electrochemical riboflavin sensor based on macroporous carbon/electroactive thionine-contained covalent organic framework

Riboflavin (RF) is one of the necessary vitamins. If human body lacks RF, it will lead to inflammation and dysfunction of mouth, lips and skin. Thus sensitive and accurate determination of RF is necessary. Here, an electroactive covalent-organic framework nanobelt (COF_TFPB-Thi) with thickness of 1.4 nm was prepared by amine-aldehyde condensation reaction between thionine and 1, 3, 5-tris (p-formylphenyl) benzene, which was then grown vertically on three-dimensional porous carbon derived from kenaf stem (3D-KSC) for double signal ratiometric electrochemical detection of RF. The resulted 3D-KSC/COF_TFPB-Thi showed two reduction peaks at -0.08 V and -0.23 V, which came from the reduction of COF_TFPB-Thi and the conjugated structure of COF_TFPB-Thi, respectively_. In the presence of RF, those RF molecules near the electrode surface were oxidized at 0.6 V. Then some oxidized RF (RF_ox) adsorbed on COF_TFPB-Thi would oxidize COF_TFPB-Thi into COF_TFPB-Thi(ox) while other RF_ox adsorbed on 3D-KSC kept unchanged. When the potential was scanned from 0.6 V to -0.6 V, both COF_TFPB-Thi(ox) and RF_ox adsorbed on 3D-KSC were reduced at -0.08 V and -0.45 V accordingly, while the reduction peak of -0.23 V of the conjugated structure of COF_TFPB-Thi kept constant. When j_-0.45/j_-0.23 was used as the response signal, the detection limit was 44 nM and the linear range was 0.13 μM -0.23 mM. By using j_-0.08/j_-0.23 as the response signal, a detection limit of 90 nM and a linear range of 0.30 μM-0.23 mM (S/N = 3) were obtained. By using double signals, the measurement results can be corrected to make the results more accurate and reliable. The sensor also showed good selectivity, reproducibility and stability, which provided a good application prospects.

Construction of manganese oxide nanowire-like cluster arrays on a DNA template: Application to detection of hydrogen peroxide

Improved electron transfer properties and catalytic activity of manganese oxide (MnOx) was demonstrated following its electrochemical deposition on a deoxyribonucleic acid (DNA) modified glassy carbon electrode. The MnOx showed different morphologies, electrocatalytic properties and electrochemical kinetics. Scanning electron microscopy showed that electrodeposition of MnOx on a bare glassy carbon electrode led to the formation of irregular-shapes while a nanowire cluster (NWC) was formed on a GCE/DNA due to the DNA serving as a template. Electrochemical impedance spectroscopy (EIS) revealed lower charge transfer resistance of the MnOxNWC compared with MnOx. A new mechanism is presented for the electrodeposition of MnOx on the surface of a GC/DNA electrode. An electrochemical biosensor was fabricated based on depositing MnOx onto a glassy carbon /DNA electrode (GCE/DNA/MnOxNWC) and was used to detect hydrogen peroxide (H₂O₂). The MnOx nanowire cluster and DNA exhibited significant electrocatalytic activity for simultaneous electrocatalytic oxidation at two oxidation potentials (0.6 V and 0.98 V vs Ag/AgCl) and one reduction potential (-0.5 V vs Ag/AgCl) for H₂O₂ at pH 6.0. A new mechanism for the detection of H₂O₂ is presented. Excellent electrocatalytic activity, stability and facility for simultaneous detection of H₂O₂ at different of applied potentials are proposed advantages of the proposed electrochemical biosensor.

Facile Solvothermal Preparation of Mn2CuO4 Microspheres: Excellent Electrocatalyst for Real-Time Detection of H2O2 Released from Live Cells

Hydrogen peroxide (H₂O₂) is an eminent biomarker in pathogenesis; a selective, highly sensitive real-time detection of H₂O₂ released from live cells has drawn a significant research interest in bioanalytical chemistry. Binary transition-metal oxides (BTMOs) displayed a recognizable benefit in enhancing the sensitivity of H₂O₂ detection; although the reported BTMO-based H₂O₂ sensor's detection limit is still insufficient, it is not appropriate for in situ profiling of trace amounts of cellular H₂O₂. In this paper, we describe an efficient, reliable electrochemical biosensor based on Mn₂CuO₄ (MCO) microspheres to assay cellular H₂O₂. The Mn₂CuO₄ microspheres were prepared through a superficial solvothermal method. It is obvious from impedance studies, introduction of manganese into copper oxide lattice significantly improved the ionic conductivity, which is beneficial for the electrochemical sensing process. Thanks to the distinct microsphere structure and excellent synergy, MCO-modified electrode exhibited excellent nonenzymatic electrochemical behavior toward H₂O₂ sensing. The MCO-modified electrode delivered a broad working range (36 nM to 9.3 mM) and an appreciable detection limit (13 nM), with high selectivity toward H₂O₂. To prove its practicality, the developed sensor was applied in the detection of cellular H₂O₂ released by RAW 264.7 cells in presence of CHAPS. These results label the possible appliance of the sensor in clinical analysis and pathophysiology. Thus, BTMOs are evolving as a promising candidate in designing catalytic matrices for biosensor applications.

Nanomaterials: Electrochemical Properties and Application in Sensors

The unique properties of nanoparticles make them an extremely valuable modifying material, being used in electrochemical sensors. The features of nanoparticles affect the kinetics and thermodynamics of electrode processes of both nanoparticles and redox reactions occurring on their surface. The paper describes theoretical background and experimental studies of these processes. During the transition from macro- to micro- and nanostructures, the analytical characteristics of sensors modify. These features of metal nanoparticles are related to their size and energy effects, which affects the analytical characteristics of developed sensors. Modification of the macroelectrode with nanoparticles and other nanomaterials reduces the detection limit and improves the degree of sensitivity and selectivity of measurements. The use of nanoparticles as transducers, catalytic constituents, parts of electrochemical sensors for antioxidant detection, adsorbents, analyte transporters, and labels in electrochemical immunosensors and signal-generating elements is described.

Electrochemical hydrogen peroxide sensor based on carbon supported Cu@Pt core-shell nanoparticles

The Cu@Pt/C nanocomposites have been synthesized via two-step reduction method. Electrochemical observations showed that the Cu@Pt/C had better electrocatalytic activity for the reduction of hydrogen peroxide than Pt/C, with a wide linear range between 0.50μM and 32.56mM, a high sensitivity of 351.3μAmM^-1cm^-2, and a low detection limit of 0.15μM (signal/noise=3). Furthermore, the sensor based on Cu@Pt/C has potential applications due to its excellent long-time stability, good reproducibility and acceptable selectivity.

A Highly Sensitive Non-Enzymatic Sensor Based on a Cu/MnO2/g-C3N4-Modified Glassy Carbon Electrode for the Analysis of Hydrogen Peroxide Residues in Food Samples

A simple and highly sensitive method for the determination of hydrogen peroxide was developed by electrodepositing Cu and MnO2 onto a g-C3N4 coated glassy carbon electrode in a one-step procedure. The morphology of the fabricated electrode material was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The electrochemical properties were measured using cyclic voltammetry (CV) and chronoamperometry. The modified sensor exhibits high catalytic activity towards electrochemical oxidation of hydrogen peroxide in a neutral phosphate buffer solution. Within the concentration ranges of 0.01–20 mM and 20–400 mM, the fabricated sensor shows a good linear relationship with the oxidation peak current, the detection limit is 0.85 × 10−6 M. Furthermore, the sensor exhibits high selectivity, good stability, and reproducibility. We successfully applied the sensor to detect hydrogen peroxide residues in food samples with satisfactory results, providing a new approach for food security evaluation.

Progress of Mimetic Enzymes and Their Applications in Chemical Sensors

The need to develop innovative and reformative approaches to synthesize chemical sensors has increased in recent years because of demands for selectivity, stability, and reproducibility. Mimetic enzymes provide an efficient and convenient method for chemical sensors. This review summarizes the application of mimetic enzymes in chemical sensors. Mimetic enzymes can be classified into five categories: hydrolases, oxidoreductases, transferases, isomerases, and induced enzymes. Potential and recent applications of mimetic enzymes in chemical sensors are reviewed in detail, and the outlook of profound development has been illustrated.