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1.
We are reviewing the state of electrochemical sensing of H2O2 based on the use of metal nanoparticles. The article is divided into subsections on sensors based on nanoparticles made from Ag, Pt, Pd, Cu, bimetallic nanoparticles and other metals. Some sensors display high sensitivity, fast response, and good stability. The review is subdivided into sections on sensors based on heme proteins and on nonenzymatic sensors. We also discussed the challenges of nanoscaled sensors and their future aspects.
Figure
Sensing mechanism of (A) mediator-based enzyme biosensor, (B) mediator-less enzyme biosensor and (C) nonenzymatic sensors with metal nanoparticles for the electrocatalytic reduction toward H2O2  相似文献   

2.
We report on a new type of indium tin oxide (ITO) electrode for sensing ascorbic acid (AA). The ITO film was modified with gold-platinum alloy nanoparticles (Au-Pt NPs) functionalized with a self-assembled film of L-cysteine. The Au-Pt NPs were electrodeposited on the ITO film and characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. A cyclic voltammetric study revealed that the electrode exhibits excellent electrocatalytic activity towards the oxidation of AA. The calibration plot for AA is linear over the concentration range from 2 to 400???M with a correlation coefficient of 0.9991. The detection limit of AA is 1???M.
Figure
Gold-platinum nanoparticles were electrodeposited on the indium tin oxide electrode surface and then self-assembled with cysteine. The resulting sensor exhibited excellent electrocatalytic activity towards the oxidation of ascorbic acid. The modified electrode is high sensitivity, easy fabrication, mediator-free and low cost.  相似文献   

3.
The fabrication concept for a low-cost sensor device using reduced graphene oxide (rGO) as the sensing material on a porous paper substrate is presented. The sensors were characterized using conductivity and capacitance measurements, atomic force microscopy and X-ray photoelectron spectroscopy. The effects of different reducing agents, graphene oxide (GO) flake size and film thickness were studied. The sensor was sensitive to NO2, and devices based on a thin (10-nm) hydrazine-reduced GO layer had the best sensitivity, reaching a 70 % reduction in resistance after 10 min of exposure to 10 ppm NO2. The sensitivity was high enough for the detection of sub-parts per million levels of NO2. Desorption of gas molecules, i.e. the recovery of the sensor, could be accelerated by UV irradiation. The structure and preparation of the sensor are simple and up-scalable, allowing their fabrication in bulk quantities, and the fabrication concept can be applied to other materials, too.
Figure
Low‐cost reduced graphene oxide based conductometric nitrogen dioxide sensitive sensor on paper  相似文献   

4.
Granular nanowires with a diameter of about 60 nm were fabricated from cuprous oxide (Cu2O) by an electrochemical method using anodic aluminium oxide as the template. A non-enzymatic sensor for hydrogen peroxide (H2O2) was then developed on the basis of a gold electrode modified with Cu2O nanowires and Nafion. The resulting sensor enables the determination of H2O2 with a sensitivity of 745 μA?mM?1?cm?2, over a wide linear range (0.25 μM to 5.0 mM), and with a low detection limit (0.12 μM). The results demonstrate that the use of such granular nanowires provides a promising tool for the design of non-enzymatic chemical sensors.
Figure
A non-enzymatic sensor for hydrogen peroxide (H2O2) was developed on the basis of a gold electrode modified with Cu2O nanowires and Nafion. The resulting sensor enables the determination of H2O2 with a sensitivity of 745 μA mM?1 cm?2, over a wide linear range (0.25 μM to 5.0 mM), and with a low detection limit (0.12 μM). The results demonstrate that the use of such granular nanowires provides a promising tool for the design of non-enzymatic chemical sensors  相似文献   

5.
We have prepared silver oxide nanoparticles (NPs) by a simple solution method using reducing agents in alkaline medium. The resulting NPs were characterized by UV–vis and FT-IR spectroscopy, X-ray powder diffraction, and field-emission scanning electron microscopy. They were deposited on a glassy carbon electrode to give a sensor with a fast response towards methanol in liquid phase. The sensor also displays good sensitivity and long-term stability, and enhanced electrochemical response. The calibration plot is linear (r 2?=?0.8294) over the 0.12?mM to 0.12?M methanol concentration range. The sensitivity is ~2.65?μAcm?2?mM?1, and the detection limit is 36.0?μM (at a SNR of 3). We also discuss possible future prospective uses of this metal oxide semiconductor nanomaterial in terms of chemical sensing.
Figure
Un-doped silver oxide NPs are prepared by solution method, which is a promising material in a wide range of environmental applications due to their attractive properties. It is characterized by UV/visible, Raman, FT-IR spectroscopy’s, powder X-ray diffraction, and FE-SEM and applied for the fabrication of sensitive methanol sensor in short response time. The analytical performances of this sensors with large-active surface area of Ag2O NPs/AgE have higher sensitivity, lower detection limit, long-term stability, and exhibit highly enhanced toxic chemicals in reliable I-V method.  相似文献   

6.
A nanocomposite consisting of a few layers of graphene (FLG) and tin dioxide (SnO2) was prepared by ultrasound-assisted synthesis. The uniform SnO2 nanoparticles (NPs) on the FLG were characterized by X-ray diffraction in terms of lattice and phase structure. The functional groups present in the composite were analyzed by FTIR. Electron microscopy (HR-TEM and FE-SEM) was used to study the morphology. The effect of the fraction of FLG present in the nanocomposite was investigated. Sensitivity, selectivity and reproducibility towards resistive sensing of liquid propane gas (LPG) was characterized by the I-V method. The sensor with 1% of FLG on SnO2 operated at a typical voltage of 1 V performs best in giving a rapid and sensitive response even at 27 °C. This proves that the operating temperature of such sensors can be drastically decreased which is in contrast to conventional metal oxide LPG sensors.
Graphical abstract Schematic of a room temperature gas sensor for liquefied petroleum gas (LPG). It is based on the use of a few-layered graphene (1 wt%)/SnO2 nanocomposite that was deposited on an interdigitated electrode (IDEs). A sensing mechanism for LPG detection has been established.
  相似文献   

7.
This paper describes the use of microdischarges as transducing elements in sensors and detectors. Chemical and physical sensing of gases, chemical sensing of liquids, and radiation detection are described. These applications are explored from the perspective of their use in portable microsystems, with emphasis on compactness, power consumption, the ability to operate at or near atmospheric pressure (to reduce pumping challenges), and the ability to operate in an air ambient (to reduce the need for reservoirs of carrier gases). Manufacturing methods and performance results are described for selected examples.
Figure
Side-view photograph of an ultraviolet light source that uses microdischarges  相似文献   

8.
The chemical transformation of the polar chloroaluminum phthalocyanine, AlClPc, to μ-(oxo)bis(phthalocyaninato)aluminum(III), (PcAl)2O, in thin films on indium tin oxide is studied and its influence on the molecular orientation is discussed. The studies were conducted using complementary spectroscopic techniques: Raman spectroscopy, X-ray photoelectron spectroscopy, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. In addition, density functional theory calculations were performed in order to identify specific vibrations and to monitor the product formation. The thin films of AlClPc were annealed in controlled environmental conditions to obtain (PcAl)2O. It is shown that the chemical transformation in the thin films can proceed only in the presence of water. The influence of the reaction and the annealing on the molecular orientation was studied with Raman spectroscopy and NEXAFS spectroscopy in total electron yield and partial electron yield modes. The comparison of the results obtained from these techniques allows the determination of the molecular orientation of the film as a function of the probing depth.
Illustration of the dimerization reaction of MClPc to (PcM)2O.  相似文献   

9.
We report on a nano-array sensor for hydrogen peroxide (H2O2) that is based on a nanoporous anodic aluminum oxide template. This was used as a matrix for the co-immobilization of horseradish peroxidase (HRP) and methylene blue (MB) on the surface of an indium tin oxide electrode. The immobilized HRP retained its natural activity and MB is capable of efficiently shuttle electrons between HRP and the electrode. The new electrode was characterized by SEM and electrochemical methods. It exhibits fast response, long-term stability, high sensitivity and good selectivity to H2O2. Under optimized conditions, it linearly responds to H2O2 in the concentration range from 1.0?μM to 26?mM, with a detection limit of 0.21?μM (at S/N?=?3).
Figure
A nano-array biosensor for hydrogen peroxide (H2O2) based on the co-electrodeposition of horseradish peroxidase (HRP) and methylene blue (MB) into anodic aluminum oxide template was constructed. The immobilized HRP could maintain natural bioactivity and MB could efficiently shuttle electrons between HRP and the electrode.  相似文献   

10.
Iron oxide microparticles were coated with 3-aminopropyltriethoxysilane and then coated with hemin via an amidation reaction. The resulting composite particles were characterized by transmission electron microscopy. FTIR spectroscopy revealed two bands (at 1,701 and 1,634 cm?1), which were assigned to the carboxy group and the amide linkage, respectively, resulting from the linkage between hemin and the amino-modified Fe3O4 particles. In addition, strong Fe-O vibrations can be observed at 563 cm?1. An electrode was modified with these microparticles and then showed a well-defined redox behavior of the immobilized hemin, with a fast heterogeneous electron transfer process (14.5 s?1). The electrode is capable of sensing both O2 and H2O2 and displays a wide linear range, high sensitivity, and fast response. The composites reported here also may serve as a support for the immobilization of proteins, which paves the way to potential applications in novel biosensors and bioelectronic devices.
Figure
Hemin was biografted onto the amine functionalized iron oxide microparticles. The composites modified electrode showed reproducible well-defined redox behavior of the attached hemin with a fast heterogeneous electron transfer process. The designed sensors for O2 and H2O2 showed good electrochemical performance, wide linear range, as well as high sensitivity and fast response.  相似文献   

11.
A multi-analyte platform based on a portable instrument is presented that enables oxygen and carbon dioxide to be determined in sample gases. The use of four sensing channels (two channels for each analyte to provide redundancy) warrants high system reliability. The sensing scheme in case of oxygen is based on the quenching of the phosphorescence of the platinum octaethylporphyrin complex. In case of carbon dioxide, a secondary inner-filter effect is exploited that is caused by a pH indicator whose color is reversibly changed. The sensing membranes were placed directly on the detectors and on the light sources so to make additional optical element dispensable, reduce system costs, avoid problems related to optical alignment, optimize the efficiency of data acquisition, and enable facile replacement of sensors. The resulting microcontroller-based system is immune against optical and electrical interferences, contains simple digital signal processing circuitry, and has low power consumption. The response of the system to the two gases was modeled, and calibration curves are corrected for effects of temperature. The instrument was characterized in terms of cross-sensitivity and dynamic response. It can determine oxygen and carbon dioxide in terms of volume percentage.
Figure
Gas sensing module for simultaneous determination of O2 and CO2  相似文献   

12.
We describe a novel surface-enhanced Raman scattering (SERS) tag that is based on Au/Ag core-shell nanostructures embedded with p-aminothiophenol. The Au/Ag core-shell sandwich nanostructures demonstrate bright and dark stripe structure and possess very strong SERS activity. Under optimum conditions, the maximum SERS signal was obtained with a 10?nm thick Ag nanoshell, and the enhancement factor is 3.4?×?104 at 1077?cm?1. After conjugation to the antibody of muramidase releasing protein (MRP), the Au/Ag core-shell nanostructures were successfully applied to an SERS-based detection scheme for MRP based on a sandwich type of immunoassay.
Figure
A novel SERS tag of p-Aminothiophenol (pATP) embedded Au/Ag core-shell nanostructures were prepared by adding precursor solution (AgNO3) into the original Au nanoparticles (NPs) solution. The synthesized SERS tags, as a biosensers, were further applied to detect a biomarker protein of SS2  相似文献   

13.
We show that the addition of white dextrin during the electrochemical deposition of platinum nanostructures (nano-Pt) on a glassy carbon electrode (GCE) results in an electrochemically active surface that is much larger than that of platinum microparticles prepared by the same procedure but in the absence of dextrin. The nano-Pt deposits are characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy, and electrochemical methods. The SEM images reveal deposits composed of mainly nanoparticles and short nanorods. The GCE was applied as a novel and cost-effective catalyst for methanol oxidation. The use of nano-Pt improves the electrocatalytic activity and the stability of the electrodes.
Figure
(A) SEM image of the Pt nanostructures. (B) Electrochemical responses of the Pt nanostructures (solid line) and Pt microparticles (line) in 1.4 M CH3OH + 0.5 M H2SO4 solution at υ?=?50 mV s?1. Novel Pt nanostructures were electrodeposited at the surface of glassy carbon electrode in the presence of white dextrin as an additive, which exhibit high electrocatalytic activity towards methanol oxidation due to their highly electrochemically active surface area.  相似文献   

14.
A sensor for hydrogen peroxide is described that is based on an indium tin oxide electrode modified with Fe3O4 magnetic nanoparticles which act as a mimic for the enzyme peroxidase and greatly improve the analytical performance of the sensor. The amperometric current is linearly related to the concentration of H2O2 in the range from 0.2 mM to 2 mM, the regression equation is y?=?-0.5–1.82x, the correlation coefficient is 0.998 (n?=?3), and the detection limit is 0.01 mM (S/N?=?3). The sensor exhibits favorable selectivity and excellent stability.
Figure
Using the peroxidase mimic property of Fe3O4 magnetic nanoparticles (MNPs), a sensitive electrochemical method with favorable analytical performance for the determination of hydrogen peroxide (H2O2) was developed.  相似文献   

15.
We report on a simple and rapid method for the preparation of a disposable palladium nanoparticle-modified graphite pencil electrode (PdNP-GPE) for sensing hydrogen peroxide (H2O2). The bare and PdNP-modified GPEs were characterized by cyclic voltammetry and SEM. The two electrodes displayed distinct electrocatalytic activities in response to the electrochemical reduction of H2O2. The amperometric detection limits were 45 nM and 0.58 mM, respectively, for the PdNP-GPE and bare-GPE, at an S/N of 3. The electrodes can be prepared simply and at low cost, and represent a promising tool for sensing H2O2.
Figure
?  相似文献   

16.
Electrochemiluminescence (ECL) integrates the advantages of electrochemical detection and chemiluminescent techniques. The method has received particular attention because it is highly sensitive and selective, has a wide linear range but low reagent costs. The use of nanomaterials with their unique physical and chemical properties has led to new kinds of biosensors that exhibit high sensitivity and stability. Compared to other nanomaterials, DNA nanostructures are more biocompatible, more hydrophilic, and thus less prone to nonspecific adsorption onto the electrode surface. We describe here a label-free and ultrasensitive ECL biosensor for detecting a cancer-associated microRNA at a femtomolar level. We have designed two auxiliary probes that cause the formation of a long-range self-assembly in the form of a μm-long 1-dimensional DNA concatamer. These can be used as carriers for signal amplification. The intercalation of the ECL probe Ru(phen)3 2+ into the grooves of the concatamers leads to a substantial increase in ECL intensity. This amplified sensor shows high selectivity for discriminating complementary target and other mismatched RNAs. The biosensor enables the quantification of the expression of microRNA-21 in MCF-7 cells. It also displays very low limits of detection and provides an alternative approach for the detection of RNA or DNA detection in diagnostics and gene analysis.
Figure
The long-range self-assembly DNA concatamers were used as carriers for signal amplification by the intercalation of numerous ECL probe (Ru(phen)3 2+) into the grooves of the DNA concatamers. Such signal amplification strategy lead to a substantial increase in ECL intensity and sensitivity.  相似文献   

17.
A novel enzyme-free electrochemical sensor for H2O2 was fabricated by modifying an indium tin oxide (ITO) support with (3-aminopropyl) trimethoxysilane to yield an interface for the assembly of colloidal gold. Gold nanoparticles (AuNPs) were then immobilized on the substrate via self-assembly. Atomic force microscopy showed the presence of a monolayer of well-dispersed AuNPs with an average size of ~4 nm. The electrochemical behavior of the resultant AuNP/ITO-modified electrode and its response to hydrogen peroxide were studied by cyclic voltammetry. This non-enzymatic and mediator-free electrode exhibits a linear response in the range from 3.0?×?10?5 M to 1.0?×?10?3 M (M?=?mol?·?L?1) with a correlation coefficient of 0.999. The limit of detection is as low as 10 nM (for S/N?=?3). The sensor is stable, gives well reproducible results, and is deemed to represent a promising tool for electrochemical sensing.
Figure
AuNPs/ITO modified electrode prepared by self-assembly method exhibit good electrocatalytic activity towards enzyme-free detection H2O2. The linear range of typical electrode is between 3.0?×?10?5 M and 1.0?×?10?3 M with a correlation coefficient of 0.999 and the limit detection is down to 1.0?×?10?8 M.  相似文献   

18.
Ferritin was immobilized on a glassy carbon electrode with electrodeposited cobalt oxide nanoparticles, and its direct electron transfer behavior was studied. It exhibits a pair of redox peaks due to direct electron transfer between ferritin and the nanoparticles. Electrochemical parameters including the formal potential (E0??), the charge transfer coefficient (??), and the apparent heterogeneous electron transfer rate constant (ks) were determined. The sensor displays excellent biocatalytic activity in terms of reduction of hydrogen peroxide, and this was applied to electrochemical sensing of hydrogen peroxide.
Figure
In this work, cobalt oxide nanoparticles were electrodeposited on the surface of an electrode for immobilization of ferritin molecules to prepare hydrogen peroxide biosensor. The immobilized protein molecules still preserve their biological activities and have great capability in catalyzing the reduction of hydrogen peroxide.  相似文献   

19.
We report on a nonenzymatic method for the determination of glucose using an electrode covered with graphene nanosheets (GNs) modified with Pt-Pd nanocubes (PtPdNCs). The latter were prepared on GNs by using N,N-dimethylformamide as a bifunctional solvent for the reduction of both metallic precursors and graphene oxide, and for confining the growth of PtPdNCs on the surface. The modified electrode displays strong and sensitive current response to the electrooxidation of glucose, notably at pH 7. The sensitivities increase in the order of Pt1Pd5NCs< Pt1Pd3NCs< Pt5Pd1NCs< Pt3Pd1NCs< Pt1Pd1NCs. At an applied potential of +0.25 V, the electrode responds linearly (R?=?0.9987) to glucose in up to 24.5 mM concentration, with a sensitivity of 1.4 μA cm?2 M?1. The sensor is not poisoned by chloride, and not interfered by ascorbic acid, uric acid and p-acetamidophenol under normal physiological conditions. The modified electrode also displays a wide linear range, good stability and fast amperometric response, thereby indicating the potential of the bimetallic materials for nonenzymatic sensing of glucose.
Figure
nonenzymatic electrochemical method was developed for glucose determination using an electrode modified with PtPd nanocubes/graphene nanosheets (PtPdNCs/GNs). The new material shows a good performance in the sensing of glucose, thus is promising for the future development of nonenzymatic glucose sensors.  相似文献   

20.
We have synthesized water-dispersible CdTe quantum dots (QDs) capped with thioglycolic acid. Their quantum yield is higher than 54%. A sensitive electrochemiluminescence (ECL) method was established based on the modification of the composite of the QDs, carbon nanotubes and chitosan on indium tin oxide glass. The sensor displays efficient and stable anodic ECL which is quenched by dopamine. A respective sensor was designed that responds to dopamine linearly in the range of 50?pM to 10?nM, and the detection limit is 24?pM. Dopamine was determined with this sensor in spiked cerebro-spinal fluid with average recoveries of 95.7%.
Figure
The CdTe quantum dots have been synthesized and therefore developed an electrochemiluminescent sensor based on immobilizing its composite with carbon nanotubes and chitosan on indium tin oxide glass. The sensor responded toward dopamine linearly in the range of 50?pM to 10?nM with a detection limit of 24?pM.  相似文献   

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