Amperometric Detection Of Hydrogen Peroxide Research Articles

Fabrication of carbon nanospheres functionalized Sm2O3/Co3O4 novel hybrid nanocomposites for selective and sensitive amperometric detection of hydrogen peroxide

Fabrication of carbon nanospheres functionalized Sm2O3/Co3O4 novel hybrid nanocomposites for selective and sensitive amperometric detection of hydrogen peroxide

In situ or Ex situ Synthesis for Electrochemical Detection of Hydrogen Peroxide-An Evaluation of Co2SnO4/RGO Nanohybrids.

Nowadays, there is no doubt about the high electrocatalytic efficiency that is obtained when using hybrid materials between carbonaceous nanomaterials and transition metal oxides. However, the method to prepare them may involve differences in the observed analytical responses, making it necessary to evaluate them for each new material. The goal of this work was to obtain for the first time Co2SnO4 (CSO)/RGO nanohybrids via in situ and ex situ methods and to evaluate their performance in the amperometric detection of hydrogen peroxide. The electroanalytical response was evaluated in NaOH pH 12 solution using detection potentials of -0.400 V or 0.300 V for the reduction or oxidation of H2O2. The results show that for CSO there were no differences between the nanohybrids either by oxidation or by reduction, unlike what we previously observed with cobalt titanate hybrids, in which the in situ nanohybrid clearly had the best performance. On the other hand, no influence in the study of interferents and more stable signals were obtained when the reduction mode was used. In conclusion, for detecting hydrogen peroxide, any of the nanohybrids studied, i.e., in situ or ex situ, are suitable to be used, and more efficiency is obtained using the reduction mode.

Fe(III)-incorporated porphyrin-based conjugated organic polymer as a peroxidase mimic for the sensitive determination of glucose and H2O2.

Nanozymes, i.e., nanomaterials that possess intrinsic enzyme-like behaviour, have thrived over the past few decades owing to their advantages of superior stability and effortless storage. Such artificial enzymes can be a perfect alternative to naturally occurring enzymes, which have disadvantages of high cost and limited functionality. In this work, we present the fabrication of an Fe(III)-incorporated porphyrin-based conjugated organic polymer as a nanozyme for the efficient detection of glucose through its intrinsic peroxidase activity and the amperometric detection of hydrogen peroxide. The iron-incorporated porphyrin-based conjugated organic polymer (Fe-DMP-POR) possesses a spherical morphology with high chemical and thermal stability. Exploiting the peroxidase-mimicking activity of the material for the determination of glucose, a detection limit of 4.84 μM is achieved with a linear range of 0-0.15 mM. The Fe-DMP-POR also exhibits a reasonable recovery range for the detection of human blood glucose. The as-synthesized material can also act as an H2O2 sensor, with a sensitivity of 947.67 μA cm-2 mM-1 and a limit of detection of 3.16 μM.

PEDOT:PSS-based screen-printable inks for H2O2 electrochemical detection

Correct levels of hydrogen peroxide in human body are of utmost importance to a variety of physiological functions. Its determination provides valuable information about specific changes that may affect our health. Here we report on PEDOT:PSS electrodes, screen printed on flexible substrates, for the amperometric detection of hydrogen peroxide at -1 V vs Ag/Ag+. PEDOT:PSS-based inks were prepared with different PEDOT-to-PSS ratios and various additives to improve viscosity, adhesion and electrical properties of the printed films. PEDOT:PSS electrodes could detect hydrogen peroxide in the range 1-100 µM with limits of detection ca. 0.97 µM, limits of quantification ca. 1.07 µM and high sensitivities up to 1.7 A·M-1·cm-2 for the best performance electrode. This work represents a relevant contribution towards non-enzymatic detection of hydrogen peroxide with an electrode fabricated using a low-cost printing process.

New carbon black-based conductive filaments for the additive manufacture of improved electrochemical sensors by fused deposition modeling.

The development of a homemade carbon black composite filament with polylactic acid (CB-PLA) is reported. Optimized filaments containing 28.5% wt. of carbon black were obtained and employed in the 3D printing of improved electrochemical sensors by fused deposition modeling (FDM) technique. The fabricated filaments were used to construct a simple electrochemical system, which was explored for detecting catechol and hydroquinone in water samples and detecting hydrogen peroxide in milk. The determination of catechol and hydroquinone was successfully performed by differential pulse voltammetry, presenting LOD values of 0.02 and 0.22 µmol L−1, respectively, and recovery values ranging from 91.1 to 112% in tap water. Furthermore, the modification of CB-PLA electrodes with Prussian blue allowed the non-enzymatic amperometric detection of hydrogen peroxide at 0.0 V (vs. carbon black reference electrode) in milk samples, with a linear range between 5.0 and 350.0 mol L−1 and low limit of detection (1.03 µmol L−1). Thus, CB-PLA can be successfully applied as additively manufactured electrochemical sensors, and the easy filament manufacturing process allows for its exploration in a diversity of applications.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s00604-022-05511-2.

Facile synthesis of copper and carbon co-doped peanut shell-like Mo2C/Mo3P electrocatalysts for ultra-sensitive amperometric detection of hydrogen peroxide

The rapid and precise detection of hydrogen peroxide has recently been a hot research in non-enzymatic electrochemical sensors. Herein, peanut shell-like Cu-Mo2C/Mo3P/C composite was simply prepared by in-situ simultaneous phosphorization and carbonization of [Cu(P4Mo6)]-based metal–organic framework (MOF) under N2/H2 atmosphere. Then, the above nanomaterials were deposited on glassy carbon electrode (GCE) surface through facile drop coating method, thus fabricating a highly efficient non-enzymatic H2O2 electrochemical sensor. In phosphate buffer solution (PBS, pH = 7.4), the Cu-Mo2C/Mo3P/C/GCE exhibits high sensitivity (653.2 μA mM−1 cm−2) and low detection limit (37 nM) to H2O2. Its amperometric response is 1.94, 3.27 and 4.71 times bigger than that of Mo2C/Mo3P/C/GCE, Mo3P/GCE and Mo2C/GCE. Such good electrochemical sensing performance is mainly ascribed to the synergism of unique microstructure, platinum-like Mo2C and Mo3P co-combination, together with copper and carbon dual-doping. Moreover, it can realize the satisfactory detection of H2O2 in human serum, disinfectant and contact lens solution, indicating the potential application in the fields of environmental monitoring and biochemical analysis.

Synthesis, Characterization, and Electrochemical Sensing Applications of Bimetallic Oxide/Carbon Nanomaterials Hybrids

Bimetallic oxide/carbon nanomaterials hybrids were chemically synthesized and fully characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), High-resolution transmission electron microscopy (HRTEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The elemental analysis confirmed the successful formation of MnCo2O4/carbon nanomaterials. The fingerprint area of FTIR showed the incorporation of the metal oxides onto CNTs and GO surfaces. Morphological investigations of the hybrids, using FESEM and HRTEM, revealed the uniform distribution of bimetallic oxides nanostructures over the surface of carbon nanomaterials. Furthermore, electrochemical characteristics were explored using the CV and EIS. The obtained electrochemical results demonstrated significant improvements in the electrocatalytic properties, in addition to the direct and fast electron transfer provided by the modified surfaces whereas the MnCo2O4/CNTs were exploited for the nano-enzymatic amperometric detection of hydrogen peroxide as an example to show the promising applications of such nanomaterials in designing high-efficiency nano-sensors and biosensors.

Facile Synthesis of Copper and Carbon Co-Doped Peanut Shell-Like Mo2c/Mo3p Electrocatalysts for Ultrasensitive Amperometric Detection of Hydrogen Peroxide

Facile Synthesis of Copper and Carbon Co-Doped Peanut Shell-Like Mo2c/Mo3p Electrocatalysts for Ultrasensitive Amperometric Detection of Hydrogen Peroxide

Facile Synthesis of Copper and Carbon Co-Doped Peanut Shell-Like Mo2c/Mo3p Electrocatalysts for Ultrasensitive Amperometric Detection of Hydrogen Peroxide

Facile Synthesis of Copper and Carbon Co-Doped Peanut Shell-Like Mo2c/Mo3p Electrocatalysts for Ultrasensitive Amperometric Detection of Hydrogen Peroxide

Highly Sensitive Amperometric Detection of Hydrogen Peroxide in Saliva Based on N-Doped Graphene Nanoribbons and MnO2 Modified Carbon Paste Electrodes.

Four different graphene-based nanomaterials (htGO, N-htGO, htGONR, and N-htGONR) were synthesized, characterized, and used as a modifier of carbon paste electrode (CPE) in order to produce a reliable, precise, and highly sensitive non-enzymatic amperometric hydrogen peroxide sensor for complex matrices. CPE, with their robustness, reliability, and ease of modification, present a convenient starting point for the development of new sensors. Modification of CPE was optimized by systematically changing the type and concentration of materials in the modifier and studying the prepared electrode surface by cyclic voltammetry. N-htGONR in combination with manganese dioxide (1:1 ratio) proved to be the most appropriate material for detection of hydrogen peroxide in pharmaceutical and saliva matrices. The developed sensor exhibited a wide linear range (1.0–300 µM) and an excellent limit of detection (0.08 µM) and reproducibility, as well as high sensitivity and stability. The sensor was successfully applied to real sample analysis, where the recovery values for a commercially obtained pharmaceutical product were between 94.3% and 98.0%. Saliva samples of a user of the pharmaceutical product were also successfully analyzed.

Elechtrochemical Analysis of Metallated Ionic Liquids for Mixed Metal Sulfide Synthesis

Driven by the ongoing transition from non-renewable to renewable energy sources, organic and hybrid solar cells have been studied due to their cost-efficiency and the smaller environmental impact. The goal of the current work is the establishment of ionic liquid precursors (ILPs) for the synthesis of complex metal chalcogenides. These can then be used in different applications including being part of the active layers of organic photovoltaic systems. The major difference to more conventional approaches is that the ILP not only acts as a metal source but also as a morphology directing template and as a stabilizer for the resulting nanoparticles.1,2 The basic idea is to use metal-containing ionic liquids, where the metal is an integral part of the IL anion as the metal source and to generate mixed metal chalcogenides directly from these single source precursors.3,4 In the current proof-of-concept study, thirteen N-butylpyridinium salts, including monometallic compounds [C4Py]2[MX4], bimetallic compounds [C4Py]2[M1-y aMy bX4] and trimetallic compounds [C4Py]2[M1-y-z aMy bMz cR4] (M = Co, Cu, Mn, Ni, Zn; y/z = 0.25, 0.33, 0.50 or 0.75; and X = Br,Cl), were synthesized and their structure and thermal and electrochemical properties were analysed. All compounds are ILs with melting points between 55 and 100 °C, Figure 1. The possibility of the direct use of these ILs in electrochemical devices was further analysed. The electronic conductivity at room temperature is between 10-4 and 10-8 S cm-1. This correlates with the optical band-gap measurements indicating rather poor semiconductors with large band gaps. However, at elevated temperature approaching the melting points, the conductivities reach up to 1.47 ∙ 10-1 S/cm at 70 ºC. Therefore future electrochemical applications are possible, especially in a moisture-sensitive environment at room temperature. Furthermore, cyclic voltammetry shows promising electrochemical stability windows between 2.5 and 3.0 V.5 A further advantage of these ILPs is the fact that their properties, such as band gaps can directly be adjusted by proper choice of the metals in the ILs. Current research includes the expansion of possible ILPs by incorporating metals like zinc and nickel, and even lanthanides, such as samarium, terbium and europium. Through a reaction of these metal-containing ILs with a sulphur source the respective metal chalcogenide (MC) nanoparticles will form.1 Current research focusses on investigating the influence of different sulfur sources. The p-type semiconductor nanoparticles will then be used as a hole transport material in the bulk heterojunction to improve the charge transport as well as providing a broad optical absorption window.1 Y. Kim, B. Heyne, A. Abouserie, C. Pries, C. Ippen, C. Günter, A. Taubert and A. Wedel, J. Chem. Phys., , DOI:10.1063/1.4991622.2 A. Abouserie, G. El-Nagar, B. Heyne, R. Sarhan, Y. Kim, C. Pries, E. Ribacki and C. Günter, Hierarchically structured Copper Sulfide Microflowers with Excellent Amperometric Hydrogen Peroxide Detection Performance, 2019.3 K. Thiel, T. Klamroth, P. Strauch and A. Taubert, Phys. Chem. Chem. Phys., 2011, 13, 13537.4 A. Abouserie, K. Zehbe, P. Metzner, A. Kelling, C. Günter, U. Schilde, P. Strauch, T. Körzdörfer and A. Taubert, Eur. J. Inorg. Chem., 2017, 5640–5649.5 C. Balischewski, K. Behrens, K. Zehbe, C. Guenter, S. Mies, E. Sperlich, A. Taubert and A. Kelling, Chem. – A Eur. J., , DOI:10.1002/chem.202003097.

Nanosized NiO Thin Films Fabricated by Sol-gel Method for Amperometric Detection of Hydrogen Peroxide at a Very Low Overpotential

Nanosized NiO Thin Films Fabricated by Sol-gel Method for Amperometric Detection of Hydrogen Peroxide at a Very Low Overpotential

Bare Platinum Nanoparticles Deposited on Glassy Carbon Electrodes for Electrocatalytic Detection of Hydrogen Peroxide

Size-tunable platinum nanoparticles (PtNPs) prepared by a facile method in an aqueous environment without the use of catalyst-poisoning reagents are used here in the electrocatalytic detection of hydrogen peroxide. Spherical nanoparticles with sizes as small as 4 and 20 nm are obtained as shown by transmission electron microscopy (TEM) analysis only using small easy-to-remove molecules such as sodium citrate. PtNPs are freed from the citrate capping agent at the surface by changing the pH to basic values and then deposited on a glassy carbon electrode by a very simple and rapid drop-casting method, achieving high cleanliness of the nanoparticle surface without the need for further treatments. The superior quality of nanoparticles on the glassy carbon is further investigated by scanning electron microscopy (SEM) analysis, which shows a highly homogeneous distribution of well-dispersed nanoparticles on the electrode surface, as well as by X-ray photoelectron spectroscopy (XPS) analysis, which confirms a drastic decrease of the citrate content, providing useful information about the citrate–platinum interaction, and evidences a related remarkable increase of conductivity of capping-free washed nanoparticles. Due to such key features, PtNPs possess excellent electrocatalytic properties, which have been tested in hydrogen peroxide electroreduction, a well-known catalytic reaction of nanostructured platinum materials. The size effect on PtNPs electrocatalytic properties is demonstrated, achieving higher performances with smaller NPs in the amperometric detection of hydrogen peroxide at −0.1 V in the concentration range of 25–750 μM, with a detection limit of 10 μM. Good sensing results toward hydrogen peroxide have also been obtained in terms of sensitivity, selectivity, repeatability, stability, and in tests performed in tap water samples. In addition, the strong adhesion of nanoparticles to the electrode surface has been verified and ascribed to their coating-free surface.

Bimetallic MOFs-derived coral-like Ag-Mo2C/C interwoven nanorods for amperometric detection of hydrogen peroxide.

Coral-like Ag-Mo2C/C-I and blocky Ag-Mo2C/C-II composites were obtained from one-step in situ calcination of [Ag(HL)3(Mo8O26)]n·nH2O [L: N-(pyridin-3-ylmethyl) pyridine-2-amine] under N2/H2 and N2 atmospheres, respectively. The coral-like morphology of Ag-Mo2C/C-I is composed of interwoven nanorods embedded with small particles, and the nano-aggregate of Ag-Mo2C/C-II is formed by cross-linkage of irregular nanoparticles. The above composites are decorated on glassy carbon electrode (GCE) drop by drop to generate two enzyme-free electrochemical sensors (Ag-Mo2C/C/GCE) for amperometric detection of H2O2. In particular, the coral-like Ag-Mo2C/C-I/GCE sensor possesses rapid response (1.2 s), high sensitivity (466.2 μA·mM-1·cm-2), and low detection limit (25 nM) towards trace H2O2 and has wide linear range (0.08 μM~4.67 mM) and good stability. All these sensing performances are superior to Ag-Mo2C/C-II/GCE, indicating that the calcining atmosphere has an important influence on microstructure and electrochemical properties. Theexcellent electrochemical H2O2 sensing performance of Ag-Mo2C/C-I/GCE sensor is mainly attributed to the synergism of unique microstructure, platinum-like electron structure of Mo2C, strong interaction between Mo and Ag, as well as the increased active sites and conductivity caused by co-doped Ag and carbon. Furthermore, this sensor has been successfully applied tothe detection of H2O2 in human serum sample, contact lens solution, and commercial disinfector, demonstrating the potential in related fields of environment and biology. Graphical abstract.

Metallated Ionic Liquids: Electrochemical Properties and Precursor Material for Mixed Metal Sulfides

Driven by the ongoing transition from non-renewable to renewable energy sources, organic and hybrid solar cells have been studied due to their cost-efficiency and the smaller environmental impact. The goal of the current work is the establishment of ionic liquid precursors (ILPs) for the synthesis of complex metal chalcogenides. These can then be used in different applications including the active layers of organic photovoltaic systems. The major difference to more conventional approaches is that the ILP not only acts as a metal source but also as a morphology directing template and as a stabilizer for the resulting nanoparticles.1,2 The basic idea is to use metal-containing ionic liquids, where the metal is an integral part of the IL anion as the metal source and to generate mixed metal chalcogenides directly from these single source precursors.3,4 In the current proof-of-concept study, thirteen N-butylpyridinium salts, including three monometallic compounds [C4Py]2[MCl4], nine bimetallic compounds [C4Py]2[M1-x aMx bCl4] and one trimetallic compound [C4Py]2[M1-y-z aMy bMz cCl4] (M = Co, Cu, Mn; x = 0.25, 0.50 or 0.75 and y = z = 0.33), were synthesized and their structure and thermal and electrochemical properties were analysed. All compounds are ILs with melting points between 69 and 93 °C. The possibility of the direct use of these ILs in electrochemical devices was further analysed. The electronic conductivity at room temperature is between 10-4 and 10-8 S cm-1. This correlates with the optical band-gap measurements indicating rather poor semiconductors with large band gaps. However, at elevated temperature approaching the melting points, the conductivities reach up to 1.47 ∙ 10-1 S/cm at 70 ºC. Therefore future electrochemical applications are possible, especially in a moisture-sensitive environment at room temperature. Furthermore, cyclic voltammetry shows promising electrochemical stability windows between 2.5 and 3.0 V.5 A further advantage of these ILPs is the fact that their properties, such as band gaps can directly be adjusted by proper choice of the metals in the ILs. Current research includes the expansion of possible ILPs by incorporating metals like zinc and nickel, and even lanthanides, such as samarium, terbium and europium, as well as incorporating different halides. Through a reaction of these metal-containing ILs with a sulphur source the respective metal chalcogenide (MC) nanoparticles will form.1 Current research focusses on investigating the influence of different sulfur sources. The p-type semiconductor nanoparticles will then be used as a hole transport material in the bulk heterojunction to improve the charge transport as well as providing a broad optical absorption window.1 Y. Kim, B. Heyne, A. Abouserie, C. Pries, C. Ippen, C. Günter, A. Taubert and A. Wedel, J. Chem. Phys., , DOI:10.1063/1.4991622.2 A. Abouserie, G. El-Nagar, B. Heyne, R. Sarhan, Y. Kim, C. Pries, E. Ribacki and C. Günter, Hierarchically structured Copper Sulfide Microflowers with Excellent Amperometric Hydrogen Peroxide Detection Performance, 2019.3 K. Thiel, T. Klamroth, P. Strauch and A. Taubert, Phys. Chem. Chem. Phys., 2011, 13, 13537.4 A. Abouserie, K. Zehbe, P. Metzner, A. Kelling, C. Günter, U. Schilde, P. Strauch, T. Körzdörfer and A. Taubert, Eur. J. Inorg. Chem., 2017, 5640–5649.5 C. Balischewski, K. Behrens, K. Zehbe, C. Guenter, S. Mies, E. Sperlich, A. Taubert and A. Kelling, Chem. – A Eur. J., , DOI:10.1002/chem.202003097.

New Synthesis of P-Type Semiconductor Mixed Metal Sulfides from Metal-Based Ionic Liquids

In light of the ongoing transition from non-renewable to renewable energy sources, organic and hybrid solar cells have been studied due to their cost-efficiency and the smaller environmental impact. The current work is aiming for the establishment of ionic liquid precursors (ILPs) for the synthesis of complex metal chalcogenides. In organic photovoltaic systems these can then be used, e.g., as the active layers due to them acting as additional p-type semiconductors. The major difference to more conventional approaches is that the ILP not only acts as a metal source but also as a morphology directing template and as a stabilizer for the resulting nanoparticles.1,2 The general approach is using metal-containing ionic liquids, where the metal is an integral part of the IL anion as the metal source and to generate mixed metal chalcogenides directly from these complex precursors.3,4 In the current proof-of-concept study, thirteen N-butylpyridinium salts, including three monometallic compounds [C4Py]2[MCl4], nine bimetallic compounds [C4Py]2[M1-x aMx bCl4] and one trimetallic compound [C4Py]2[M1-y-z aMy bMz cCl4] (M = Co, Cu, Mn; x = 0.25, 0.50 or 0.75 and y = z = 0.33), were synthesized and their structure, thermal, optical and electrochemical properties were analysed. All compounds are ILs with melting points between 69 and 93 °C. The successful synthesis of mixed metal ILs with distinct compositions was confirmed using ICP OES, with single crystal X-ray diffraction showing consistent asymmetric units. Furthermore, X-ray diffraction shows that all ILs are isostructural, thus confirming that both the anion and the cation are stable and reliable building blocks for MILs. A possible application regarding the direct use of these ILs in electrochemical devices was further analysed. The electronic conductivity at room temperature is between 10-2 and 10-8 S cm-1. This correlates with the optical band-gap measurements indicating rather poor semiconductors with large band gaps. However, at elevated temperature approaching the melting points, the conductivities reach up to 1.47 ∙ 10-1 at 70 ºC. As a result, future electrochemical applications are possible, especially in a moisture-sensitive environment at room temperature. Moreover, corrosive behaviour and the correlation between conductivity and composition were investigated for the first time, e.g. showing a positive influence with the addition of manganese into the compound, possibly acting as an electron scavenger. Additionally, cyclic voltammetry shows promising electrochemical stability windows between 2.5 and 3.0 V.5 Furthermore, a big advantage of these ILPs is the fact that their properties, such as band gaps, can directly be adjusted by proper choice of the metals in the ILs. Through a reaction of these metal-containing ILs with a sulphur source the respective metal chalcogenide (MC) nanoparticles will form.1 The p-type semiconductor nanoparticles will then be used as a hole transport material in the bulk heterojunction to improve the charge transport as well as providing a broad optical absorption window.1 Y. Kim, B. Heyne, A. Abouserie, C. Pries, C. Ippen, C. Günter, A. Taubert and A. Wedel, J. Chem. Phys., , DOI:10.1063/1.4991622.2 A. Abouserie, G. El-Nagar, B. Heyne, R. Sarhan, Y. Kim, C. Pries, E. Ribacki and C. Günter, Hierarchically structured Copper Sulfide Microflowers with Excellent Amperometric Hydrogen Peroxide Detection Performance, 2019.3 K. Thiel, T. Klamroth, P. Strauch and A. Taubert, Phys. Chem. Chem. Phys., 2011, 13, 13537.4 A. Abouserie, K. Zehbe, P. Metzner, A. Kelling, C. Günter, U. Schilde, P. Strauch, T. Körzdörfer and A. Taubert, Eur. J. Inorg. Chem., 2017, 2017, 5640–5649.5 C. Balischewski, K. Behrens, K. Zehbe, C. Günter and A. Taubert, In preparation.

Activity determination of human monoamine oxidase B (Mao B) by selective capturing and amperometric hydrogen peroxide detection

The enzyme monoamine oxidase B (Mao B), which is involved in dopamine metabolism, is an important drug target in Parkinson’s disease (PD). The medical treatment with several Mao B inhibitors is well established but only little personalized since the monitoring of the patients Mao B activity is complex and requires sophisticated laboratory equipment. To demonstrate an approach, which has potential in the personalization of the medical PD treatment, a sensorial Mao B activity determination system has been developed. Here, the enzyme activity is quantified by electrochemical detection of enzymatically produced H2O2. Therefore, the enzyme is enriched from solution via cellulose particles with specific antibodies against human Mao B. The successful capturing of the enzyme can be verified by means of SDS-PAGE. For activity determination the enzyme is brought in contact with a suitable substrate - here benzylamine. Selectivity of the amperometric hydrogen peroxide detection in the presence of co-reactants has been verified. Within the time span of 30 min, a linear dependency of enzymatically produced H2O2 with the substrate incubation time can be observed. This allows the evaluation of the Mao B activity. The results have been correlated to an optical detection method. Furthermore, the method has been tested for different amounts of enzyme used in the experiments.

Modified pencil graphite electrode as a low-cost glucose sensor

A manganese oxides mediator was electrodeposited onto a low-cost pencil graphite electrode (PE) from an easily available and affordable potassium permanganate precursor. The modified manganese oxides coated PE (MnOxides/PE) was previously utilized as a hydrogen peroxide sensor according to its electrocatalytic activity for hydrogen peroxide oxidation in an ammonium buffer (pH 9.0) medium. The amperometric detection of hydrogen peroxide is possible at +0.50 V vs Ag/AgCl instead of +0.80 V vs Ag/AgCl using an unmodified PE. Further modification of the MnOxides/PE with glucose oxidase immobilization converted the modified PE into a glucose sensor by hydrogen peroxide detection in a phosphate buffer (pH 7.4) at the same operating potential. The linear concentration range of glucose detection by the batch technique was 0.056–1.41 mM, with a sensitivity of 2.19 μA mM−1. A detection limit of 18.3 μM and a percentage RSD of 5.0% were obtained from five different sensors. Through the flow injection analysis technique, a low-cost open-flow cell containing a volume of 1.4 mL was fabricated from a plastic vial and a micropipette tip. Using the injection volume of 200 μL and flow rate of 1 mL min−1, the linear concentration range of glucose detection was determined to be 0.56–5.55 mM, with the sensitivity of 0.72 μA mM−1, the detection limit of 0.29 mM, the response time of 20 s, and sample throughput of 34 samples per hour. The application of the proposed sensor to detect glucose in sport and energy drink samples showed good precision, with the percentage RSD of 0.7–5.6% (n = 3) and a recovery percentage of 97–103%.

Nonenzymatic Hydrogen Peroxide Electrochemical Sensor Based on Inkjet-Printed Reduced Graphene Oxide

The vital role of hydrogen peroxide (H2O2) in many enzyme-catalyzed reactions, has attracted much interest to develop novel approaches for accurate and fast detection of this simple compound [2]. Also, the determination of the hydrogen peroxide level is essential in food processing, environmental analysis, and clinical diagnosis [2]. Reduced graphene oxide (rGO) has shown to be a superior electrode material for electrochemical analysis due to its high electron transfer rate and active surface area [3]. However, the fabrication of such rGO-based electrodes involves complicated and expensive fabrication processes. Herein, we present a disposable, simple, and low-cost H2O2 electrochemical sensor based on rGO for amperometric detection of hydrogen peroxide concentration.First, the rGO ink material was prepared by mixing 10 ml of graphene oxide (GO) solution with 10 ml of DI water, and sodium dodecyl sulfate (2 mg/ml). The SDS works as a surfactant and reduces the possibility of printer nozzle clogging. The solution was sonicated for 30 minutes and was loaded to a cartridge of an office inkjet printer. To achieve a thicker layer of GO, the printing process was repeated 25 times on a PET film. Next, the electrodes were placed inside hydroiodic (HI) acid for 24 hours at 100 oC to remove oxygenated groups from GO molecular structure. The color of the electrodes became darker after the GO was reduced to rGO (Figure 1.A). Then, the printed pattern was sliced into 20 by 2.5 mm electrodes, and the resistance of the electrode was measured to validate the reduction process.The step voltammetry method was adopted to measure the H2O2 inside 0.1 M PBS buffer. The solution was stirred at 200 rpm, and -800 mV vs. Ag/AgCl was applied to the working electrode. As it is shown in Figure 1.B, after the addition of 100 µM of H2O2, the current increases due to the reduction of H2O2. Finally, the selectivity of the sensor was evaluated against ascorbic acid and glucose.In summary, the rGO-based electrochemical sensor was fabricated by inkjet printing graphene oxide with a regular office inkjet printer followed by chemical reduction procedure. The sensor was used to determine the hydrogen peroxide level in aqueous solution. Inkjet-printed rGO electrodes can be used for simple and precise measurement of hydrogen peroxide with high selectivity and sensitivity.

Amperometric detection of hydrogen peroxide and its density functional theory for adsorption on Ag/TiO2 nanohybrid

Silver/titania (Ag/TiO2) nanocomposites, synthesized through a simple one-step chemical reduction method, are used for electrochemical sensing of hydrogen peroxide (H2O2). The images of transmission electron microscopic (TEM) demonstrate a well dispersion of Ag nanoparticles (NPs) with a particle size range of approximately 3 nm on the TiO2 surface, which makes the sensor based on Ag/TiO2 exhibit an excellent performance toward H2O2. The AgNPs presented in the nanocomposite exhibit electrocatalytic reduction of H2O2 and the limit of detection (LOD) is found to be 1.23 µM. Density functional theory (DFT) calculation studies reveal that H2O2 could be easily adsorbed onto Ag rather than TiO2 surface of Ag/TiO2 via a partial electron transfer from Ag to H2O2. The nanocomposite-modified electrode has also excellent selectivity toward the detection of H2O2 over the interferents even when the interferents have a 100 times higher concentration than H2O2.