Oxide Electrochemical Sensor Research Articles

Nitrogen-Doped Indium Oxide Electrochemical Sensor for Stable and Selective NO2 Detection.

Efficient gas sensors are critical for environmental monitoring and industrial safety. While metal oxide semiconductor (MOS) sensors are cost-effective, they struggle with poor selectivity, high operating temperatures, and limited stability. Electrochemical sensors, though selective and energy-efficient, face high costs, and stability issues due to precious metal catalysts like platinum on carbon (Pt/C). Herein, a novel, cost-effective electrochemical sensor using nitrogen-doped indium oxide In2O3- xN2 x /3Vx /3 (0.01≤x≤0.14), synthesized with varying nitriding times is presented. The optimized In2O3 N-40min sensor demonstrates a remarkable response current of 771 nA to 10ppm nitrogen dioxide (NO2) at ambient temperature, with outstanding long-term stability (over 30 days) and rapid response/recovery times (5/16 s). Compared to Pt/C sensors, it shows 84% and 67% reductions in response and recovery times, respectively, and maintains 98% performance after a month, versus 68% for Pt/C. This cost-effective sensor presents a promising alternative for electrochemical gas sensing, eliminating the need for precious metal catalysts.

Performance Improvement of Indium Tin Oxide Electrochemical Sensor by Mixing Carbon Black

Performance Improvement of Indium Tin Oxide Electrochemical Sensor by Mixing Carbon Black

Halim-mediated zinc oxide electrochemical sensor for copper detection in aqueous solution

Halim-mediated zinc oxide electrochemical sensor for copper detection in aqueous solution

Characterization of Benchtop-Fabricated Arrays of Nanowrinkled Surface Electrodes as a Nitric Oxide Electrochemical Sensor.

In this work, we present an accessible benchtop fabrication technique to obtain a planar array of gold nanowrinkled surface electrodes (ANSE) for the construction of electrochemical cells, specifically to monitor soluble biomarkers of interest in cell culture environments. We present a complete characterization of the array and its response as an electrochemical cell. To validate our sensor, we evaluated the device sensitivity to detect nitric oxide (NO), an important molecule produced by endothelial cells as a response to environmental signals such as mechanics and growth factors. While testing measurements of nitric oxide in aqueous solutions with isotonic salt concentrations, we evidenced the influence of the environmental conditions for such electrochemical measurements, showing that the aqueous medium, usually not accounted for, significantly impacts the outcome. Finally, we present the application of the electrochemical sensor for the detection of nitric oxide released from stimulated endothelial cells as a proof of concept.

Rational Design of Cu-Doped Tetrahedron of Spinel Oxide for High-Performance Nitric Oxide Electrochemical Sensor

The real-time detection of nitric oxide (NO) in living cells is essential to reveal its physiological processes. However, the popular electrochemical detection strategy is limited to the utilization of noble metals. The development of new detection candidates without noble metal species still maintaining excellent catalytic performance has become a big challenge. Herein, we propose a spinel oxide doped with heteroatom-Cu-doped Co3O4 (Cu-Co3O4) for the sensitive and selective detection of NO release from the living cells. The material is strategically designed with Cu occupying the tetrahedral (Td) center of Co3O4 through the formation of a Cu-O bond. The introduced Cu regulates the local coordination environment and optimizes the electronic structure of Co3O4, hybridizing with the N 2p orbital to enhance charge transfer. The CuTd site can well inhibit the current response to nitrite (NO2-), resulting in a high improvement in the electrochemical oxidation of NO. The selectivity of Cu-Co3O4 can be markedly improved by the pore size of the molecular sieve and the negative charge on the surface. The rapid transmission of electrons is due to the fact that Cu-Co3O4 can be uniformly and densely in situ grown on Ti foil. The rationally designed Cu-Co3O4 sensor displays excellent catalytic activity toward NO oxidation with a low limit of detection of 2.0 nM (S/N = 3) and high sensitivity of 1.9 μA nM-1 cm-2 in cell culture medium. The Cu-Co3O4 sensor also shows good biocompatibility to monitor the real-time NO release from living cells (human umbilical vein endothelial cells: HUVECs; macrophage: RAW 264.7 cells). It was found that a remarkable response to NO was obtained in different living cells when stimulated by l-arginine (l-Arg). Moreover, the developed biosensor could be used for real-time monitoring of NO released from macrophages polarized to a M1/M2 phenotype. This cheap and convenient doping strategy shows universality and can be used for sensor design of other Cu-doped transition metal materials. The Cu-Co3O4 sensor presents an excellent example through the design of proper materials to implement unique sensing requirements and sheds light on the promising strategy for electrochemical sensor fabrication.

Rapid determination of malondialdehyde in serum samples using a porphyrin-functionalized magnetic graphene oxide electrochemical sensor

An electrochemical sensor based on a screen-printed carbon electrode (SPCE) modified with porphyrin-functionalized magnetic graphene oxide (TCPP-MGO) was developed for the sensitive and selective determination of malondialdehyde (MDA), an important biomarker of oxidative damage, in serum samples. The coupling of TCPP with MGO allows the exploitation of the magnetic properties of the material for separation, preconcentration, and manipulation of analyte, which is selectively captured onto the TCPP-MGO surface. The electron-transfer capability in the SPCE was improved through derivatization of MDA with diaminonaphthalene (DAN) (MDA-DAN). TCPP-MGO-SPCEs have been employed to monitor the differential pulse voltammetry (DVP) levels of the whole material, which is related to the amount of the captured analyte. Under optimum conditions, the nanocomposite-based sensing system has proved to be suitable for the monitoring of MDA, presenting a wide linear range (0.01–100 µM) with a correlation coefficient of 0.9996. The practical limit of quantification (P-LOQ) of the analyte was 0.010 µM, and the relative standard deviation (RSD) was 6.87% for 30 µM MDA concentration. Finally, the developed electrochemical sensor has demonstrated to be adequate for bioanalytical applications, presenting an excellent analytical performance for the routine monitoring of MDA in serum samples.Graphical abstract

Introducing Graphene–Indium Oxide Electrochemical Sensor for Detecting Ethanol in Aqueous Samples with CCD-RSM Optimization

There is significant demand for portable sensors that can deliver selective and sensitive measurement of ethanol on-site. Such sensors have application across many industries, including clinical and forensic work as well as agricultural and environmental analysis. Here, we report a new graphene–indium oxide electrochemical sensor for the determination of ethanol in aqueous samples. Graphene layers were functionalised by anchoring In2O3 to its surface and the developed composite was used as a selective electrochemical sensor for sensing ethanol through cyclic voltammetry. The detection limit of the sensor was 0.068 mol/L and it showed a linear response to increasing ethanol in the environment up to 1.2 mol/L. The most significant parameters involved and their interactions in the response of the sensor and optimization procedures were studied using a four-factor central composite design (CCD) combined with response surface modelling (RSM). The sensor was applied in the detection of ethanol in authentic samples.

Sensitive Detection of 4-Nitrophenol in Water Based on Functionalized Pyridine Diketopyrrolopyrrole-Graphene Oxide Electrochemical Sensor

Sensitive Detection of 4-Nitrophenol in Water Based on Functionalized Pyridine Diketopyrrolopyrrole-Graphene Oxide Electrochemical Sensor

Molecularly Imprinted Polymer Functionalized on Reduced Graphene Oxide Electrochemical Sensor for Detection of Ciprofloxacin

Ciprofloxacin (CIP) is widely utilised to treat bacterial infections. Currently, CIP is present in water sources at higher concentrations, thus necessitating close monitoring. This study developed electrochemical nano-sensors based on molecularly imprinted polymer (MIP) and reduced graphene oxide (rGO) composites to detect CIP. rGO served as the loading platform for MIP immobilisation on a glassy carbon electrode (GCE). A copolymer thin film, comprised of polyaniline copolymerized with o-phenylenediamine (PAni-co-PDA) was obtained by electro-polymerisation utilizing cyclic voltammetry (CV) under suitable conditions. The performance of the modified GCE was examined utilizing CV mode in a hexacyanoferrate electrolyte as an electrochemical probe. The PAni-co-PDA/rGO-modified GCE exhibited enhanced improvement and efficient electrocatalytic behaviour in the oxidation of CIP with relatively high sensitivity and stability. The sensor was operated in differential pulse voltammetry (DPV) mode. Our best results revealed good linearity response to CIP in the range of 0.001–10.0 μM with an R-squared of 0.949, a detection limit of 0.09 μM (3.3 SD/S), and the calibration plot of ΔI minus the logarithm of the CIP concentration exhibited a sensitivity of –1.521. The sensor demonstrated a conductive polymer-based device that can be utilised for rapid CIP determination in pharmaceutical samples and biological fluids.

An efficient and simple method using a graphite oxide electrochemical sensor for the determination of glyphosate in environmental samples

Excessive and indiscriminate use of the herbicide glyphosate (GLY) leaves the environment susceptible to its contamination. This work describes the development of a simple, inexpensive, and efficient electroanalytical method using graphite oxide paste electrode (GrO-PE) for the direct determination of GLY traces in groundwater samples, soybean extracts, and lettuce extracts. Under optimal experimental conditions, the developed sensor exhibited a linear response of the peak current intensity vs. the concentration, in the range of 1.8 × 10−5 to 1.2 × 10−3 mol L−1 for GLY. The limits of detection and quantification are 1.7 × 10−8 mol L−1 and 5.6 × 10−8 mol L−1, respectively. The methodology developed here demonstrated a strong analytical performance, with high reproducibility, repeatability, and precision. Moreover, it successfully avoided interference from other substances, showing high selectivity. The GrO-PE sensor was effectively applied to determine GLY traces in real samples with recovery rates ranging from 98% to 102%. Results showed that the GrO-PE is effective and useful for GLY detection, with the advantage of not involving laborious modifications and complicated handling, making it a promising tool for environmental analysis.

Enhanced electrochemical sensitivity towards plasticizer determination based on ferrocene- end-cap dendrimer functionalized graphene oxide electrochemical sensor

We fabricated a novel sensitive ferrocene end-cap polyester dendrimer (Fc-PED)- graphene oxide (GO) modified glassy carbon electrode (Fc-PED/GO/GCE) for direct quantification of Di(2-methoxyethyl) phthalate (DMEP) in liquor sample. GO sheets were bonded on the Fc-PED molecules by the chemical reaction between Fc-PED and GO sheets to form Fc-PED-GO composites. Construction of electrochemical sensors using the structure of nano-sized dendrimer will offer compact matrix for the incorporation of GO sheets, which provided more possibilities for the design of sensor to improve the film forming performance and the electrochemical activity of the electrode. GO sheet also provided a larger surface area to facilitate deposition of Fc-PED redox probe, which increased the current response of the modified sensor. The Fc-PED/GO/GCE sensor demonstrated a wide linear detection range of 0.06-1200 μmol.L−1with a low detection limit of 0.04μmol.L−1. Furthermore, the sensor showed higher sensitivity, good selectivity and reproducibility towards DMEP detection. The feasibility of the electrochemical sensor was proved by successful detection of DMEP in real liquor samples. Possible synergistic effect of Fc-PED and GO towards DMEP detection are proposed based on experimental results.

A Co3O4 nano-octahedron modified fluorine doped tin oxide electrochemical sensor for detection of benzobicyclon

Unique Co3O4 nano-octahedrons for modifying electrode were synthesized through simple chemical reaction. This versatile Co3O4 nanostructure possesses the combined advantages of morphological stability and high porosity that can buffer volume change during electrochemical cycles, shorten diffusion path of electron transport, and exhibit remarkable overall electrochemical performance. Samples were characterized by field transmission electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffractometry, Fourier transform infrared spectroscopy and electrochemical impedance spectroscopy. An electrode modified by this material was used for detection of benzobicyclon. Square wave voltammetry showed that there was a linear relationship between peak current and concentration in the range of 10.00–582.96 μmol L−1 with a detection limit (S/N = 3) of 0.38 μmol L−1. The modified electrode was used for detection of benzobicyclon in brown rice and rice straw samples with satisfactory recovery, reproducibility and stability. Modified electrodes reported in the literature that were prepared by different methods resulted in other kinds of surface morphologies that did not exhibit the same level of performance.

A novel β-cyclodextrin Functionalized Reduced Graphene Oxide Electrochemical Sensor for Blood Glucose Detection

A novel β-cyclodextrin Functionalized Reduced Graphene Oxide Electrochemical Sensor for Blood Glucose Detection

The Utility of the Nitric Oxide Electrochemical Sensor in Biomedical Research

In recent years World Precision Instruments Inc. (WPI) produced for commercial use a selective and sensitive electrochemical sensor for the detection of the important biological free radical nitric oxide (NO). Though many kinds of NO sensors are now commercially available WPI offers a range of sensors of variable size and applicability for the detection of NO in vivo and in in vitro biomedical samples. This article overviews the working characteristics of the sensors and their utility for biomedical research.

Evaluation of the nonbiofouling behaviour of nitric oxide electrochemical sensor materials by using sessile drop contact angle measurements and free enthalpy of adhesion calculations

In this study, we report the development of the concept of additivity of intramolecular forces at interfaces to calculate the free energy of adhesion of standard fouling agent models, namely human serum albumin (HSA), bovine serum albumin (BSA) and polyethyleneglycol (PEG) onto nitric oxide (NO) electrochemical sensor materials. This constitutes the first example of antibiofouling tendency evaluation of NO sensors, which may allow to predict their efficiency when used in complex biological systems. This was carried out by developing sessile drop contact angle measurements of three liquids of different polarity (water, glycerol and α-bromonaphtalene) onto the chemically modified sensor surfaces, and determining the free enthalpy of adhesion of the standard fouling agent models. Correlation between these calculations and experimentally determined sensitivities of the designed microsensors to NO in BSA-containing solution is also discussed.