Construction Of Electrochemical Sensor Research Articles

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.

The synergistic effect of Au-COF nanosheets and artificial peroxidase Au@ZIF-8(NiPd) rhombic dodecahedra for signal amplification for biomarker detection

Here, a new type of signal amplification strategy is proposed employing Au nanoparticle (AuNP)-functionalized covalent organic framework (Au-COF) nanosheets and AuNP functionalized ZIF-8(NiPd) (Au@ZIF-8(NiPd)) rhombic dodecahedra nanocomposites for sandwich electrochemical sensor construction. The peroxidase mimics Au@ZIF-8(NiPd) took the place of natural enzymes in enzyme-assisted amplification strategies, both acting as catalysts for H2O2 reduction for signal amplification, and serving as ideal nanocarriers for signal probe anchoring. The cancer biomarker thrombin (TB) was selected as the target. Thrombin binding aptamers (TBA 2) were fixed on Au@ZIF-8(NiPd), and the obtained TBA 2-Au@ZIF-8(NiPd) bioconjugates were employed as tracer labels, and TB was sandwiched between the tracer labels and capture probe TBA 1 which were immobilized on the Au-COF nanosheet modified electrode. Au-COFs with a high specific area, super electroconductivity, and uniformly distributed AuNPs were utilized as the electrode substrate to fix TBA 1. Exploiting the sandwich method, the proposed TB aptasensor exhibited a wide linear range of 0.1 pM to 20 nM with a low detection limit of 15 fM (S/N = 3). The ingenious sensing strategy enriched the application diversity of the artificial enzyme and showed promise in research and development of point-of-care diagnostics.

New Generation of Electrochemical Sensors Based on Multi-Walled Carbon Nanotubes

Multi-walled carbon nanotubes (MWCNT) have provided unprecedented advances in the design of electrochemical sensors. They are composed by sp2 carbon units oriented as multiple concentric tubes of rolled-up graphene, and present remarkable active surface area, chemical inertness, high strength, and low charge-transfer resistance in both aqueous and non-aqueous solutions. MWCNT are very versatile and have been boosting the development of a new generation of electrochemical sensors with application in medicine, pharmacology, food industry, forensic chemistry, and environmental fields. This work highlights the most important synthesis methods and relevant electrochemical properties of MWCNT for the construction of electrochemical sensors, and the numerous configurations and successful applications of these devices. Thousands of studies have been attesting to the exceptional electroanalytical performance of these devices, but there are still questions in MWCNT electrochemistry that deserve more investigation, aiming to provide new outlooks and advances in this field. Additionally, MWCNT-based sensors should be further explored for real industrial applications including for on-line quality control.

Preparation of highly conductive biochar nanoparticles for rapid and sensitive detection of 17β-estradiol in water

We developed a sensitive and cost effective sensor based on highly conductive and adsorptive biochar nanoparticles for electrochemical detection of 17β-estradiol. The biochar is ubiquitous and has the advantages of large specific surface area, cost effectiveness, and good stability, which has the potential to be utilized for electrode construction as long as the conductivities are guaranteed. We obtained nano sized biochar particles (BCNPs) and investigated electrochemical properties of the BCNPs with variation of the pyrolysis conditions. BCNPs with high conductivity (BCNP800) were obtained and utilized for reproducible and stable electrochemical sensor construction. The produced highly conductive BCNP800 sensor had exhibited improved amperometric responses such as decreased impedance, lowered anodic potential and enhanced current signal toward 17β-estradiol compared with the pristine glassy carbon electrode. In addition, the adsorption-accumulation by BCNP800 for 17β-estradiol resulted in great sensing signal amplification. With synergetic effect of high adsorption and conductivity properties of the BCNP800 sensor a detection limit of 11.30 nM was obtained. The accuracy and reliability of the BCNP800 sensor were confirmed to be compatible with the high performance liquid chromatography analysis and it could be successfully applied for real environmental water analysis.

Ferrocene-terminated dendrimer functionalized graphene oxide layered sensor toward highly sensitive evaluation of Di(2-ethylhexyl) phthalate in liquor samples

We demonstrate the use of a dendrimer functionalized graphene oxide (GO) to fabricate a novel sensitive ferrocene-terminated poly(amine) ester dendrimer (Fc-AED)-GO modified glassy carbon electrodes (Fc-AED/GO/GCE) for direct quantification of Di(2-ethylhexyl) phthalate (DEHP) in liquor sample. GO sheets were grafted on the Fc-AED molecules by the esterification reaction between carboxylic end group in Fc-AED and hydroxyl group on GO sheets so as to form Fc-AED-GO composites. Construction of electrochemical sensors using the structure of nanosized dendrimer can provide compact matrix for the incorporation of GO to improve the adhesion of GO on electrode, which would be more possible for the design of sensor to improve the film forming performance and then increase the electrochemical activity of the electrode. Additionally, it can directly use the redox probe of ferrcene to sense the content variation of analyte. The GO also provides a larger surface area to facilitate deposition of Fc-AED redox probe resulting in the increased current response of the modified sensor. The modified sensor exhibites a wide linear response to DEHP and a low detection limit of 0.06 μM with higher sensitivity, good selectivity, and a better reproducibility promising to be a useful tool in the DEHP evaluation. The outstanding performance of the developed sensor could be attributed to the synergistic effect of Fc-AED and GO. Possible redox mechanism of DEHP on Fc-AED/GO/GCE are proposed based on experimental results.

Simultaneous electrochemical sensing of hydroquinone and catechol using nanocomposite based on palygorskite and nitrogen doped graphene

Abstract A novel electrochemical sensor based on nitrogen doped graphene (NGE) and palygorskite (Pal) for the simultaneous detection of hydroquinone (HQ) and catechol (CT) has been proposed. Pal is particularly pointed out for its appreciable specific surface area and reactive-OH groups on its surface. Acid treatment Pal demonstrated better physico-chemical properties, which are propitious to electrochemical sensor construction. The introduction of NGE not only improved the poor conductivity of Pal but also served as an excellent adherent matrix. The modified electrode demonstrated the enhanced redox peak currents of HQ and CT with good discrimination. Under optimized conditions, the linear ranges for HQ and CT were 2–50 μM and 1–50 μM, with detection limit (LOD) of 0.8 μM and 0.13 μM, respectively. The result designates that the Pal/NGE composite promises to be a new eco-friendly modified material for sensor fabrication.

Electrochemical sensor construction based on Nafion/calcium lignosulphonate functionalized porous graphene nanocomposite and its application for simultaneous detection of trace Pb2+ and Cd2+

Here, a new porous graphene (PGR) based nanocomposite was synthesized by a chemical and thermal reduction of graphite oxide in the assistance of calcium lignosulfonate (CLS), and characterized by scanning electron microscopy SEM, TEM, XPS, Zeta potential analysis, FTIR and EIS. Then the as-prepared CLS/PGR was used along with Nafion to modify a glassy carbon electrode (GCE) for constructing electrochemical sensor to detect Pb2+ and Cd2+ simultaneously. Compared with the bare GCE, the reduced graphene oxide/GCE, and the CLS/PGR/GCE, the Nafion/CLS/PGR/GCE exhibited improved electrochemical performance in detecting the two ions. It could be ascribed to the synergistic contribution from PGR, CLS and Nafion, which integrated the advantageous features of high active surface area, good cation exchange ability and strong adsorption capacity. Under optimum conditions, this novel sensor showed a wide detection range for Pb2+ and Cd2+ (0.05–5.0 μM) with the limit of detection and limit of quantification for Pb2+ 0.01 and 0.03 μM, for Cd2+ 0.003 and 0.01 μM, respectively. It was successfully applied for the simultaneous determination of Pb2+ and Cd2+ in real water samples with satisfying recoveries of 93.6–105.3% for Pb2+ and 93.5–102.5% for Cd2+, demonstrating its feasibility for the determination of environmental metallic pollutants.

The Use of CeO2-TiO2 Nanocomposites as Enzyme Immobilization Platforms in Electrochemical Sensors

The use of metal oxide-based nanoparticles plays a key role in the development of electrochemical sensors with superior properties such as high sensitivity, wide linear range, low limit of detection, and long storage stability. In this work, we aimed to synthesize CeO 2 -TiO 2 mixed metal oxide nanoparticles which were used as substrate materials for the immobilization of biorecognition element for the construction of enzyme-based electrochemical sensors. For this purpose, in the first part of the study, CeO 2 -TiO 2 nanoparticles were prepared via a low temperature co-precipitation method and characterized using X-ray Diffraction (XRD), N 2 -adsorption, and Transmission Electron Microscopy (TEM) methods. The XRD results confirmed the successful synthesis of CeO 2 -TiO 2 mixed metal oxide nanoparticles with the average crystalline size of 8.51 nm. The calculated crystalline size value was compatible with that obtained from the TEM images. The N 2 adsorption results revealed a large surface area of 78.6 cm 2 g -1 which is essential for the construction of electrochemical sensors with improved performance. The electrochemical sensors were developed by the deposition of nanoparticles on the surface of a Pt electrode, followed by the immobilization of lactate oxide enzyme. The electrochemical performance of the sensors was evaluated by cyclic voltammetry (CV) and chronoamperometry methods. The constructed sensors showed a sensitivity of 0.085 ± 0.008 µA µM -1 cm -2 (n=5) with a high reproducibility (RSD % = 1.3) and a wide linear range (0.02-0.6 mM). In addition, the detection limit towards lactate was found be 5.9 µM. The results indicated that the use of CeO 2 -TiO 2 nanoparticles used as a modifier on the surface of the Pt electrode enabled the construction of electrochemical lactate sensors with high sensitivity.

An Overview of Pesticide Monitoring at Environmental Samples Using Carbon Nanotubes-Based Electrochemical Sensors

Carbon nanotubes have received enormous attention in the development of electrochemical sensors by promoting electron transfer reactions, decreasing the work overpotential within great surface areas. The growing concerns about environmental health emphasized the necessity of continuous monitoring of pollutants. Pesticides have been successfully used to control agricultural and public health pests; however, intense use can cause a number of damages for biodiversity and human health. In this sense, carbon nanotubes-based electrochemical sensors have been proposed for pesticide monitoring combining different electrode modification strategies and electroanalytical techniques. In this paper, we provide a review of the recent advances in the use of carbon nanotubes for the construction of electrochemical sensors dedicated to the environmental monitoring of pesticides. Future directions, perspectives, and challenges are also commented.

Comparison of different carbon nanostructures influence on potentiometric performance of carbon paste electrode

Recently, different carbon nanomaterials were introduced for construction of electrochemical sensors. In this study, the influence of carbon nanomaterial on performance of carbon paste potentiometric electrode was investigated. In this manner, different kinds of carbon nanomaterial, i.e., graphene, graphene oxide and carbon nanotube (CNT) were used as a conduction phase in carbon paste electrode. Then, potentiometric characteristics of the corresponding paste electrodes such as calibration slope, linear range, detection limit, response time and stability were compared with each other. The results appeared comprehensive findings about the role of electrode’s content in electrochemical performance.

Synthesis of Surface Molecularly Imprinted Poly(methacrylic acid-hemin) on Carbon Nanotubes for the Voltammetric Simultaneous Determination of Antioxidants from Lipid Matrices and Biodiesel

This paper reports the synthesis of novel nanocomposite based on multi-walled carbon nanotubes (MWCNT) covalently bonded by molecularly imprinted poly(methacrylic acid-hemin) (MIP-MWCNT) using tert-butylhydroquinone (TBHQ) as template molecule and its use in the construction of electrochemical sensor. Chemical, physical and morphological structure of nanocomposite was characterized by FT-IR, TGA, SEM, TEM and textural analysis. The electrochemical sensor highly selective to TBHQ was prepared by drop-casting a suspension of nanocomposite on the surface of a glassy carbon electrode. From cyclic voltammetry, it was observed that the electrochemical sensor modified with MIP-MWCNT exhibited great recognition performance, higher analytical response and catalytic properties towards the TBHQ when compared to NIP-MWCNT (nanocomposite polymerized without adding TBHQ), MIP-MWCNT without hemin and MIP-hemin without MWCNT. Such results demonstrated the synergic effect of imprinting influence, MWCNT and hemin in improving the performance of electrochemical sensor. From chronoamperometric measures, the electrochemical sensor modified with MIP-MWCNT could recognize TBHQ selectively in the presence of electroactives and structurally similar compounds. Under optimized conditions by pulse differential voltammetry (pulse amplitude of 100mV, pulse time of 25ms and scan rate of 10mVs−1) and measures in 0.15molL−1H2SO4, the proposed method successfully enabled the simultaneous determination of TBHQ and butylated hydroxyanisole (BHA), yielding limits of detection of 0.85 and 0.50μmolL−1, respectively. The feasibility of the method was checked by simultaneous determination of TBHQ and BHA in soybean oil, margarine, mayonnaise and biodiesel, whose results were statistically equal to those achieved by high performance liquid chromatography (HPLC).

Electrochemical Sensors Based on Molybdenum Disulfide Nanomaterials

AbstractNanostructured molybdenum disulfide (MoS2) has been arousing great research interest in many fields in recent years due to their peculiar properties. In this short review, we introduce recent advances in nanostructured MoS2 as potential materials for construction of electrochemical sensors. The potential application prospect of the electrochemical sensors based on MoS2 nanomaterials is proposed.

Formation of flowerlike gold nanostructure on ordered mesoporous carbon electrode and its application in electrochemical determination of ractopamine

Via an electrodeposition process, flowerlike gold nanostructure was formed on an ordered mesoporous carbon electrode surface. The morphology and kinetic characteristics of this gold/ordered mesoporous carbon composite material were characterized with scanning electron microscope and cyclic voltammograms. To further discover the potential application of the present material, an electrochemical sensor toward ractopamine determination was constructured. The satisfying evaluation results of the sensor indicated that the material is expected to be used in the design and construction of electrochemical sensors.

Sensing Properties of Multiwalled Carbon Nanotubes Grown in MW Plasma Torch: Electronic and Electrochemical Behavior, Gas Sensing, Field Emission, IR Absorption

Vertically aligned multi-walled carbon nanotubes (VA-MWCNTs) with an average diameter below 80 nm and a thickness of the uniform VA-MWCNT layer of about 16 μm were grown in microwave plasma torch and tested for selected functional properties. IR absorption important for a construction of bolometers was studied by Fourier transform infrared spectroscopy. Basic electrochemical characterization was performed by cyclic voltammetry. Comparing the obtained results with the standard or MWCNT‐modified screen-printed electrodes, the prepared VA-MWCNT electrodes indicated their high potential for the construction of electrochemical sensors. Resistive CNT gas sensor revealed a good sensitivity to ammonia taking into account room temperature operation. Field emission detected from CNTs was suitable for the pressure sensing application based on the measurement of emission current in the diode structure with bending diaphragm. The advantages of microwave plasma torch growth of CNTs, i.e., fast processing and versatility of the process, can be therefore fully exploited for the integration of surface-bound grown CNTs into various sensing structures.

Highly stable pyridinic nitrogen doped graphene modified electrode in simultaneous determination of hydroquinone and catechol

A highly stable pyridinic nitrogen doped graphene (pyridine-NG) was used as an excellent electrocatalyst for the construction of electrochemical sensor for simultaneous determination of hydroquinone (HQ) and catechol (CC) in 0.20M pH 5.5 acetate buffer solution. At the pyridine-NG modified electrode, both HQ and CC can cause a pair of quasi-reversible redox peaks and the potential difference of oxidation peaks between HQ and CC was 103mV. Under the optimized condition, the oxidation peak current of HQ was linear over the range from 5 to 200μM in the presence of 100μM CC, and the oxidation peak current of CC was linear over the range from 5 to 200μM in the presence of 100μM HQ. The detection limit is 0.38μM for HQ and 1μM for CC (S/N=3). This proposed sensor was successfully applied to the simultaneous determination of HQ and CC in artificial sample, and the results were good stability and high reproducibility. The excellent electrocatalysis of pyridine-NG can be due to the π–π interactions between the benzene ring of CC and graphene layer, the hydrogen bonds formed between hydroxyl in HQ molecule and pyridinic nitrogen atoms within graphene layers, especially the less density distribution of π electron cloud in pyridinic-NG in acidic condition.

Molecularly Imprinted Polymer-Hybrid Electrochemical Sensor for the Detection of β-Estradiol

This paper discusses the construction of a novel electrochemical sensor for 17β-estradiol (E2) based on a molecularly imprinted polymer (MIP)-conducting polymer modified hybrid electrode. A bifunctional monomer, N-phenylethylene diamine methacrylamide (NPEDMA), was used for the construction of the electrochemical sensor. Conducting films were prepared on the surface of a gold electrode by electropolymerization of the aniline moiety of NPEDMA. A layer of MIP was photochemically grafted over the polyaniline, via N,N-diethyldithiocarbamic acid benzyl ester (iniferter) activation of the methacrylamide groups. Computational modeling was used to select the most suitable monomer for preparation of MIPs for E2. Experimental parameters such as deposition time, cyclic voltammetric (CV) scan cycles, and conditions for polymer accumulation were optimized. The detection limit of the resulting sensor, determined by CV, was 6.86 × 10–7 M. Furthermore, the hybrid electrode was successfully used to analyze E2 in water without complex sample pretreatment. These results reveal that the MIP hybrid sensor has potential to be an effective technique for the electrochemical determination of E2 in real-time in complicated matrices.

Construction of Electrochemical Sensor Based on Poly Dopamine-Hyaluronic Acid Composite Membrane for Detection of Hydrogen Peroxide

Construction of Electrochemical Sensor Based on Poly Dopamine-Hyaluronic Acid Composite Membrane for Detection of Hydrogen Peroxide

Application of thermally reduced graphene oxide modified electrode in simultaneous determination of dihydroxybenzene isomers

Thermally reduced graphene oxide (TRGO) was used as an excellent electrocatalyst for the construction of electrochemical sensor for simultaneous determination of dihydroxybenzene isomers including hydroquinone (HQ), catechol (CC) and resorcinol (RC). The surface morphology and structure of TRGO were investigated by utilizing transmission electron microscope, scanning electron microscopy, atomic force microscope, Raman spectroscopy and X-ray diffraction. The electrode modified with TRGO shows excellent electrocatalytic activity toward the oxidation of HQ, CC and RC. As a result, the oxidation peaks of three isomers in pH 6.0 PBS can be clearly discriminated due to large peak potential separation among them. In addition, HQ and CC can be simultaneously determined by using differential pulse voltammetry without any separation step. Under the optimized condition, the detection limits of HQ and CC are 0.75 and 0.8 μM (S/N = 3) with linear ranges of 1–500 μM in the presence of 50 μM isomer, respectively. The proposed method was successfully applied to the simultaneous determination of CC and HQ in synthetic water sample with reliable recovery. The proposed sensor has some important advantages such as low cost, ease of preparation, good stability and high reproducibility. Therefore, the present work promises for the application of graphene modified electrode in the simultaneous determination of multiple analytes.

Controllable Deposition of a Platinum Nanoparticle Ensemble on a Polyaniline/Graphene Hybrid as a Novel Electrode Material for Electrochemical Sensing

We demonstrate for the first time an interfacial polymerization method for the synthesis of high-quality polyaniline-modified graphene nanosheets (PANI/GNs), which represents a novel type of graphene/polymer heterostructure. The interfacial polymerization at a liquid-liquid interface allows PANI to grow uniformly on the surface of the GNs. An ultra-high loading of Pt nanoparticles was then controllably deposited on the surface of the PANI/GNs to form a Pt/PANI/GNs hybrid. The obtained composites were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The Pt/PANI/GNs hybrid shows excellent electrocatalytic activity toward methanol oxidation and oxygen reduction. H(2)O(2) and glucose were used as two representative analytes to demonstrate the sensing performance of a Pt/PANI/GNs-modified electrode. It is found that this sensing element shows high sensitivity and a low detection limit for H(2)O(2) and glucose. The results demonstrate that the Pt/PANI/GNs hybrid may be an attractive and advanced electrode material with potential applications in the construction of electrochemical sensors and biosensors.

Composite materials based on ormosil for the construction of electrochemical sensors and biosensors

Sol-gel process has gained tremendous attention in past decades for the preparation of pure and composite material for numerous applications. Organically modified sol-gel glasses (ormosils) have hybrid properties of rigid inorganic silica matrix and organic functionalities. Ormosils provide ambient environment for bio-molecules encapsulation and such systems have been used widely for biosensor applications. Biological elements including enzymes, antibodies, antigens, DNA, whole cells, tissues, proteins, biologically derived material, and biomimetic materials provide the possibility of biological recognition to the device and transducer to detect the biological signals with the help of associated electronics and software to amplify these signals into a readable form for the user. In this review we report on the formation of sol-gel based composite materials primarily on ormosil along with carbon nano tubes, metal nano particles, mediators, inorganic complexes, polymers, ionomers and biological materials and cite the electrochemical sensor/biosensor system based on it.