Sensitive Amperometric Sensor Research Articles

Highly sensitive amperometric detection of drugs and antioxidants on non-functionalized multi-walled carbon nanotubes: Effect of metallic impurities?

This work demonstrates that the electrochemistry of different molecules of pharmaceutical interest, including omeprazole, ciprofloxacin, dopamine, catechol, hydroquinone, and the antioxidants tert-butylhydroquine, gallic acid, propyl gallate, and pyrogallol, is affected by the functionalization of multi-walled carbon nanotubes (MWCNTs). Voltammetric and amperometric measurements confirmed the improved analytical characteristics of the GCE modified with non-functionalized (NF) MWCNTs (as-received) in comparison with functionalized MWCNTs (F-MWCNTs). Increase in voltammetric responses (up to 10-fold), higher slope values for the amperometric detection of the analytes (up to 7-fold) and, for some molecules, widening of the linear working range, were verified. Electrochemical impedance spectroscopy measurements also revealed higher electrochemical activity of non-functionalized MWCNTs. The presence of metallic impurities on NF-MWCNTs, removed by functionalization with HNO3/H2SO4, may contribute the improved performance of NF-MWCNT-modified electrodes; however, decrease in electroactive area of F-MWCNTs has to be considered. Although acid functionalization introduced oxygenated groups on the MWCNT structure, the presence of metallic impurities (Fe and Co) and higher electroactive area of NF-MWCNTs play major role on the increase in sensitivity of the electrochemical sensors. As a conclusion, we propose the use of pristine MWCNTs to produce more sensitive amperometric sensors.

Fabrication of sensitive enzymatic biosensor based on multi-layered reduced graphene oxide added PtAu nanoparticles-modified hybrid electrode.

A highly sensitive amperometric glucose sensor was developed by immobilization of glucose oxidase (GOx) onto multi-layer reduced graphene oxide (MRGO) sheets decorated with platinum and gold flower-like nanoparticles (PtAuNPs) modified Au substrate electrode. The fabricated MRGO/PtAuNPs modified hybrid electrode demonstrated high electrocatalytic activities toward oxidation of H2O2, to which it had a wide linear response that ranged from 0.5 to 8 mM (R2 = 0.997), and high sensitivity of 506.25 μA/mMcm2. Furthermore, glucose oxidase-chitosan composite and cationic polydiallyldimethylammonium chloride (PDDA) were assembled by a casting method on the surface of MRGO/PtAuNPs modified electrode. This as-fabricated hybrid biosensor electrode exhibited high electrocatalytic activity for the detection of glucose in PBS. It demonstrated good analytical properties in terms of a low detection limit of 1 μM (signal-to-noise ratio of 3), short response time (3 s), high sensitivity (17.85 μA/mMcm2), and a wide linear range (0.01–8 mM) for glucose sensing. These results reveal that the newly developed sensing electrode offers great promise for new type enzymatic biosensor applications.

A glassy carbon electrode modified with FeS nanosheets as a highly sensitive amperometric sensor for hydrogen peroxide

Iron sulfides with different atomic ratios were synthesized by a hydrothermal method and used to modify a glassy carbon electrode. The various sulfides were compared to each other for their amperometric response to H2O2. It is found that FeS is the most adequate material. Operated in 0.1 M NaOH solution at 0.4 V (vs. Ag/AgCl), the sensor based on FeS displays a linear response that extends from 0.50 μM to 20.5 mM of H2O2, with a sensitivity of 36.4 μA mM−1 cm−2 and a detection limit of 0.15 μM (at an S/N ratio of 3). The sensor is selective, stable and reproducible.

Highly Sensitive Amperometric Sensor for Eugenol Quantification Based on CeO2 Nanoparticles and Surfactants

AbstractAmperometric sensor for eugenol based on glassy carbon electrode (GCE) modified with CeO2 nanoparticles dispersed in surfactant was fabricated. The effect of surfactant nature (sodium dodecylsulfate, cetylpyridinium bromide (CPB) and Brij® 35) on eugenol voltammetric behaviour was tested. In comparison to CeO2‐H2O/GCE, CeO2‐CPB/GCE showed 2.8‐fold increased current and 70 mV cathodic shift of potential in the diffusion‐controlled irreversible electrooxidation. The electrodes were characterized with SEM and EIS. CeO2‐CPB/GCE showed significantly lower charge transfer resistance (2.6±0.3 kΩ vs. 20±1 kΩ for CeO2‐H2O/GCE and 173±9 kΩ for GCE). Under conditions of DPV, the sensor linear dynamic range is 0.075‐75.0 μM of eugenol with the limits of detection (LOD) and quantification (LOQ) of 19.1 and 63.8 nM, respectively. The sensor exhibited high sensitivity, selectivity, good reproducibility and fast response and was applied for the real samples analysis (essential oils and clove spices). The results obtained correspond well to the data of spectrophotometric method.

Highly Sensitive Electrochemical Hydrogen Peroxide Sensor Based on Iron Oxide‐Reduced Graphene Oxide‐Chitosan Modified with DNA‐Celestine Blue

AbstractThe present study describes a novel and very sensitive electrochemical assay for determination of hydrogen peroxide (H2O2) based on synergistic effects of reduced graphene oxide‐ magnetic iron oxide nanocomposite (rGO‐Fe3O4) and celestine blue (CB) for electrochemical reduction of H2O2. rGO‐Fe3O4 nanocomposite was synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X‐ray diffraction (XRD), electrochemical impedance spectroscopy and cyclic voltammetry. Chitosan (Chit) was used for immobilization of amino‐terminated single‐stranded DNA (ss‐DNA) molecules via a glutaraldehyde (GA) to the surface of rGO‐Fe3O4. The MTT (3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) results confirmed the biocompatibility of nanocomposite. Experimental parameters affecting the ss‐DNA molecules immobilization were optimized. Finally, by accumulation of the CB on the surface of the rGO‐Fe3O4‐Chit/ssDNA, very sensitive amperometric H2O2 sensor was fabricated. The electrocatalytic activity of the rGO‐Fe3O4‐Chit/DNA‐CB electrode toward H2O2 reduction was found to be very efficient, yielding very low detection limit (DL) of 42 nM and a sensitivity of 8.51 μA/μM. Result shows that complex matrices of the human serum samples did not interfere with the fabricated sensor. The developed sensor provided significant advantages in terms of low detection limit, high stability and good reproducibility for detection of H2O2 in comparison with recently reported electrochemical H2O2 sensors.

A Facile Electrochemical Preparation of Reduced Graphene Oxide@Polydopamine Composite: A Novel Electrochemical Sensing Platform for Amperometric Detection of Chlorpromazine.

We report a novel and sensitive amperometric sensor for chlorpromazine (CPZ) based on reduced graphene oxide (RGO) and polydopamine (PDA) composite modified glassy carbon electrode. The RGO@PDA composite was prepared by electrochemical reduction of graphene oxide (GO) with PDA. The RGO@PDA composite modified electrode shows an excellent electro-oxidation behavior to CPZ when compared with other modified electrodes such as GO, RGO and GO@PDA. Amperometric i-t method was used for the determination of CPZ. Amperometry result shows that the RGO@PDA composite detects CPZ in a linear range from 0.03 to 967.6 μM. The sensor exhibits a low detection limit of 0.0018 μM with the analytical sensitivity of 3.63 ± 0.3 μAμM–1 cm–2. The RGO@PDA composite shows its high selectivity towards CPZ in the presence of potentially interfering drugs such as metronidazole, phenobarbital, chlorpheniramine maleate, pyridoxine and riboflavin. In addition, the fabricated RGO@PDA modified electrode showed an appropriate recovery towards CPZ in the pharmaceutical tablets.

Highly sensitive amperometric Nafion-based CO sensor using Pt/C electrodes with different kinds of carbon materials

In this paper, a novel amperometric CO sensor using Nafion and Pt/C composite electrodes was fabricated. Three kinds of carbon materials (carbon fibers, multiwall carbon nanotubes and carbon blacks) were utilized as the supports of the sensing and reference electrodes for the CO sensors. The results revealed that the effective Pt loadings on the electrodes increased in the following order: carbon fibers (CFs)>multiwall carbon nanotubes (MWCNTs)>carbon blacks (CBs), leading to the increasing of the sensitivities toward CO in same order. In other words, the sensor using Pt/CFs as the sensing electrode (SE) showed the highest sensitivity with the value of 0.077μA/ppm and shortest response time in the range of CO concentration from 1 to 200ppm at room temperature. Further, a reproducible and stable response against 50ppm CO was obtained for the sensor with Pt/CFs SE materials. Moreover, a low detection limit of 0.1ppm for CO was also examined, suggesting that the sensor can be convenient for detecting very low traces of CO.

Highly Sensitive Amperometric Sensor for the Determination of Glucose at Histidine Stabilized Copper Nanospheres Decorated Multi-Walled Carbon Nanotubes

Highly Sensitive Amperometric Sensor for the Determination of Glucose at Histidine Stabilized Copper Nanospheres Decorated Multi-Walled Carbon Nanotubes

Highly sensitive amperometric hydrazine sensor based on novel α-Fe2O3/crosslinked polyaniline nanocomposite modified glassy carbon electrode

Fabrication of efficient chemical sensors is a prime strategy for detecting trace levels of environmental species, but predominantly limited by slow response time, relatively low sensitivity and poor selectivity. Here, we demonstrate, for the first time, the synthesis of a novel nanocomposite of α-Fe2O3/crosslinked polyaniline (α-Fe2O3/CPANI) via a simultaneous gelation and polymerization process. The newly prepared α-Fe2O3/CPANI nanocomposite was employed as an efficient hydrazine chemical sensor with high sensitivity and selectivity. The XRD, XPS and HR-TEM results confirmed the presence of PANI and revealed a well-crystalline, structurally uniform crystals of rhombohedral α-Fe2O3 phase with particle sizes <50nm and distinctly lattice fringes of 3.7Å. The electrochemical detection of hydrazine was conducted at α-Fe2O3/CPANI modified glassy carbon electrode (GCE) by the cyclic voltammetry and amperometry techniques and compared with bare GCE or pure α-Fe2O3. Comparing to bare GCE or pure α-Fe2O3, the α-Fe2O3/CPANI nanocomposite modified GCE shows a superior sensing performance, leading to a remarkable sensitivity of 1.93μAμM−1cm−2, a very low limit of detection (LOD) of 0.153μM at (S/N=3), a wide linear range of hydrazine concentrations from 0.2μM to 40μM, with a correlation coefficient (R2)=0.9983 and a response time <12s. Additionally, the present α-Fe2O3/CPANI modified electrode exhibits electrochemical stability and high selectivity as a negligible cross-sensitivity to common bio-active interfering species and several metal ions was observed. Furthermore, the electrocatalytic reaction obeys the first order kinetics with respect to hydrazine concentration with a diffusion dominated process. Such a novel nanocomposite of α-Fe2O3/CPANI represents a proper electrode material for highly efficient detection of hydrazine by electrochemistry.

Non-enzymatic amperometric detection of hydrogen peroxide in human blood serum samples using a modified silver nanowire electrode

In this paper, we report a highly sensitive amperometric H2O2 sensor based on silver nanowires (AgNWs) modified screen printed carbon electrode. The AgNWs were synthesized using polyol method. The synthesized AgNWs were characterized by scanning electron microscopy, UV–vis spectroscopy and X-ray diffraction techniques. The average diameter and length of the synthesized AgNWs were found as 86±5 and 385nm, respectively. Under optimum conditions, the AgNWs modified electrode shows a stable amperometric response for H2O2 and was linear over the concentrations ranging from 0.3 to 704.8μM. The non-enzymatic sensor showed a high sensitivity of 662.6μAmM−1cm−2 with a detection limit of 29nM. The response time of the sensor was found as 2s. Furthermore, the AgNWs modified electrode exhibited a good recovery of H2O2 (94.3%) in the human blood serum samples.

Prussian Blue/Reduced Graphene Oxide Composite for the Amperometric Determination of Dopamine and Hydrogen Peroxide

Prussian blue has significant application for the construction of electrochemical biosensors. In this work, Prussian blue-reduced graphene oxide modified glass carbon electrodes were successfully fabricated using electrochemical deposition. The high surface area of graphene oxide enhanced the deposition of Prussian blue and the resulting electrocatalytic activity. Infrared spectroscopy and scanning electron microscopy showed that the relatively porous Prussian blue was on the surface of reduced graphene oxide. Cyclic voltammetry showed that Prussian blue-coated reduced graphene oxide composite films improved electron transfer compared to Prussian blue films. The Prussian blue-reduced graphene oxide composite film provided higher response for the reduction of hydrogen peroxide and the oxidation of dopamine compared with the Prussian blue film due to synergistic effects between the reduced graphene oxide and Prussian blue particles. The sensitivity of the electrode was 0.1617 µA µM−1 cm−2. The linear dynamic range extended from 0.5 µM to 0.7 mM dopamine with a limit of detection equal to 125 nM. This work provided a versatile strategy for the design and construction of sensitive amperometric sensors with robust electrocatalytic behavior.

Spherulitic copper-copper oxide nanostructure-based highly sensitive nonenzymatic glucose sensor.

In this work, three different spherulitic nanostructures Cu–CuOA, Cu–CuOB, and Cu–CuOC were synthesized in water-in-oil microemulsions by varying the surfactant concentration (30 mM, 40 mM, and 50 mM, respectively). The structural and morphological characteristics of the Cu–CuO nanostructures were investigated by ultraviolet–visible (UV–vis) spectroscopy, X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy techniques. The synthesized nanostructures were deposited on multiwalled carbon nanotube (MWCNT)-modified indium tin oxide (ITO) electrodes to fabricate a nonenzymatic highly sensitive amperometric glucose sensor. The performance of the ITO/MWCNT/Cu–CuO electrodes in the glucose assay was examined by cyclic voltammetry and chronoamperometric studies. The sensitivity of the sensor varied with the spherulite type; Cu–CuOA, Cu–CuOB, and Cu–CuOC exhibited a sensitivity of 1,229, 3,012, and 3,642 µA mM−1·cm−2, respectively. Moreover, the linear range is dependent on the structure types: 0.023–0.29 mM, 0.07–0.8 mM, and 0.023–0.34 mM for Cu–CuOA, Cu–CuOB, and Cu–CuOC, respectively. An excellent response time of 3 seconds and a low detection limit of 2 µM were observed for Cu–CuOB at an applied potential of +0.34 V. In addition, this electrode was found to be resistant to interference by common interfering agents such as urea, cystamine, L-ascorbic acid, and creatinine. The high performance of the Cu–CuO spherulites with nanowire-to-nanorod outgrowths was primarily due to the high surface area and stability, and good three-dimensional structure. Furthermore, the ITO/MWCNT/Cu–CuOB electrode applied to real urine and serum sample showed satisfactory performance.

Highly sensitive amperometric CO sensor using nanocomposite C-loaded PdCl2–CuCl2 as sensing electrode materials

A novel C-loaded PdCl2–CuCl2 electrode material was prepared by the facile method without the use of any additive or organic active agent. It was used to fabricate a solid-state planar electrochemical carbon monoxide sensor. The effect of the working electrode used in amperometric gas sensors on the performance of sensitivity, detection limit was evaluated. The results showed that the sensor has characteristics of a practical-use level: response time, 10s; range, 0–100ppm; sensitivity, 0.35μA/ppm.

Carboxyl Multiwalled Carbon Nanotubes through Ultrasonic Dispersing in Dimethylfomamide Modified Electrode as a Sensitive Amperometric Sensor for Detection of Sulfonamide

Carboxyl Multiwalled Carbon Nanotubes through Ultrasonic Dispersing in Dimethylfomamide Modified Electrode as a Sensitive Amperometric Sensor for Detection of Sulfonamide

A Sensitive Amperometric Sensor for the Determination of Dopamine at Graphene and Bismuth Nanocomposite Film Modified Electrode

A Sensitive Amperometric Sensor for the Determination of Dopamine at Graphene and Bismuth Nanocomposite Film Modified Electrode

Electrochemical Determination of Bromate in Different Types of Flour and Bread by a Sensitive Amperometric Sensor Based on Palladium Nanoparticles/Graphene Oxide Nanosheets

In the present work, a novel amperometric sensor for bromate detection and determination based on palladium nanoparticles supported by graphene oxide nanosheets (PdNPs-GO) modified glassy carbon (GC) electrode was fabricated. The graphene nanosheets were functionalized using a novel method, and palladium nanoparticles were synthesized by electrodeposition method. The surface morphology of modified electrodes was investigated using scanning electron microscopy (SEM). Determination and investigation of electrochemical parameters of bromate reduction were performed using rotating disk electrode (RDE) amperometry and cyclic voltammetry (CV) methods, respectively. The experimental data showed that PdNPs-GO/GC electrode has significant electrocatalytic activity toward bromate reduction. A wide concentration range (1–10 μM and 10–1,000 μM) with a good detection limit (1.05 × 10−7 M) were achieved. Also, this sensor has a short response time (15 s) and its sensitivity is 7.428 A/Mcm2. The accuracy of the proposed method was investigated by recovery experiments in different flour and bread samples where good recoveries were obtained (between 94 and 110 %). Furthermore, this electrode exhibited remarkable stability, repeatability, and selectivity.

An amperometric nanobiosensor for the selective detection of K+-induced dopamine released from living cells

A highly sensitive amperometric sensor has been studied for selective monitoring of K+-induced dopamine released from dopaminergic cells (PC12) which is based on an EDTA immobilized-poly(1,5-diaminonaphthalne) (poly-DAN) layer comprising graphene oxide (GO) and gold nanoparticles (GO/AuNPs). The integration of a negatively charged probe molecule on the poly-DAN/GO/AuNPs nanohybrid attained the signal enhancement to discriminate dopamine (DA) molecules from foreign species by catalytic effect and surface charge, and hydrogen bonding-based interactions with a probe molecule. The sensor performance and morphology were investigated using voltammetry, impedance spectrometry, SEM, and XPS. Experimental variables affecting the analytical performance of the sensor probe were optimized, and linear response was observed in the range of 10nM−1µM with a detection limit of 5.0nM (±0.01) for DA. Then, the sensor was applied to monitor dopamine released from PC12 cells upon extracellular stimulation of K+ ions. It was also confirmed that K+-induced dopamine release was inhibited by a calcium channel inhibitor (Nifidipine). The results demonstrated that the presented biosensor could be used as an excellent tool for monitoring the effect of exogenous agents on living cells and drug efficacy tests.

A sensitive and selective enzyme-free amperometric glucose biosensor using a composite from multi-walled carbon nanotubes and cobalt phthalocyanine

In the present study, a simple and sensitive amperometric enzyme-free glucose sensor was developed at a multiwalled carbon nanotube and cobalt phthalocyanine (MWCNT–CoTsPc) modified electrode.

A Sensitive Amperometric Sensor for the Determination of Sophocarpine Based on Vertically Oriented Graphene Nanosheets Modified Glassy Carbon Electrode

We presented to fabricate the electrodeposition of the film of reduced graphene oxide (ERGO) with preferred vertical orientation on the glassy carbon electrode through pulse potential method (PPM). The ERGO film were characterized by electrochemical methods and scanning electron microscopy. For the first time, the electrodeposition of the film was applied to develop a highly sensitive electrochemical sensor for determination of sophocarpine. The electrochemical behavior of sophocarpine was then studied by cyclic voltammetry. The results revealed that the ERGO film can effectively increase response toward the oxidation of sophocarpine by greatly enhancing the oxidation peak currents and decrease the overpotential of sophocarpine. Under the selected conditions, the sensor showed good amperometric response for sophocarpine within a wide linear range from 1.0 × 10−6 to 1.0 × 10−4 mol L−1 and a low detection limit of 3.0 × 10−7 mol L−1. At the same time, the method was also successfully applied to the quantitative determination of sophocarpine in spiked human urine and its result was satisfactory.

Fabrication of a highly sensitive amperometric sensor using 1,4-phenylene-N,N′-bis (O,O-diphenylphoramidate)/CdS quantum dots/multi-walled carbon nanotubes for nanomolar detection of captopril

A novel modified glassy carbon electrode (GCE) based on a new synthesized compound 1,4-phenylene-N,N′-bis (O,O-diphenylphoramidate) (PDPP), l-cysteine capped CdS quantum dots (CdS-QDs) and multi-walled carbon nanotubes (MWCNTs) was prepared. After studying the redox properties of the modified electrode by cyclic voltammetry, it was used as an electrochemical sensor for oxidation of captopril (CAP). Combination of CdS-QDs and MWCNTs with PDPP considerably improved the current response of the GCE towards electrocatalytic oxidation of CAP. Under hydrodynamic conditions (stirred solutions) at a fixed potential, oxidation current was proportional to the CAP concentration and calibration plot was linear over the concentration range of 0.05–90μM and detection limit was found to be 15nM. The results of applying the proposed amperometric sensor for the determination of CAP in spiked urine and tablet were also encouraging.