Preparation and characterization of AuNPs/CNTs-ErGO electrochemical sensors for highly sensitive detection of hydrazine.

Science.gov (United States)

Zhao, Zhenting; Sun, Yongjiao; Li, Pengwei; Zhang, Wendong; Lian, Kun; Hu, Jie; Chen, Yong

2016-09-01

A highly sensitive electrochemical sensor of hydrazine has been fabricated by Au nanoparticles (AuNPs) coating of carbon nanotubes-electrochemical reduced graphene oxide composite film (CNTs-ErGO) on glassy carbon electrode (GCE). Cyclic voltammetry and potential amperometry have been used to investigate the electrochemical properties of the fabricated sensors for hydrazine detection. The performances of the sensors were optimized by varying the CNTs to ErGO ratio and the quantity of Au nanoparticles. The results show that under optimal conditions, a sensitivity of 9.73μAμM(-1)cm(-2), a short response time of 3s, and a low detection limit of 0.065μM could be achieved with a linear concentration response range from 0.3μM to 319μM. The enhanced electrochemical performances could be attributed to the synergistic effect between AuNPs and CNTs-ErGO film and the outstanding catalytic effect of the Au nanoparticles. Finally, the sensor was successfully used to analyse the tap water, showing high potential for practical applications. Copyright © 2016 Elsevier B.V. All rights reserved.

A Review on the Electrochemical Sensors and Biosensors Composed of Nanowires as Sensing Material

Directory of Open Access Journals (Sweden)

Shen-Ming Chen

2008-01-01

Full Text Available The development and application of nanowires for electrochemical sensors and biosensors are reviewed in this article. Next generation sensor platforms will require significant improvements in sensitivity, specificity and parallelism in order to meet the future needs in variety of fields. Sensors made of nanowires exploit some fundamental nanoscopic effect in order to meet these requirements. Nanowires are new materials, which have the characteristic of low weight with extraordinary mechanical, electrical, thermal and multifunctional properties. The advantages such as size scale, aspect ratio and other properties of nanowires are especially apparent in the use of electrical sensors such as electrochemical sensors and in the use of field-effect transistors. The preparation methods of nanowires and their properties are discussed along with their advantages towards electrochemical sensors and biosensors. Some key results from each article are summarized, relating the concept and mechanism behind each sensor, with experimental conditions as well as their behavior at different conditions.

Electrochemical sensors: a powerful tool in analytical chemistry

Directory of Open Access Journals (Sweden)

Stradiotto Nelson R.

2003-01-01

Full Text Available Potentiometric, amperometric and conductometric electrochemical sensors have found a number of interesting applications in the areas of environmental, industrial, and clinical analyses. This review presents a general overview of the three main types of electrochemical sensors, describing fundamental aspects, developments and their contribution to the area of analytical chemistry, relating relevant aspects of the development of electrochemical sensors in Brazil.

Electrochemical Sensors Based on Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Md. Aminur Rahman

2009-03-01

Full Text Available This review focuses on recent contributions in the development of the electrochemical sensors based on carbon nanotubes (CNTs. CNTs have unique mechanical and electronic properties, combined with chemical stability, and behave electrically as a metal or semiconductor, depending on their structure. For sensing applications, CNTs have many advantages such as small size with larger surface area, excellent electron transfer promoting ability when used as electrodes modifier in electrochemical reactions, and easy protein immobilization with retention of its activity for potential biosensors. CNTs play an important role in the performance of electrochemical biosensors, immunosensors, and DNA biosensors. Various methods have been developed for the design of sensors using CNTs in recent years. Herein we summarize the applications of CNTs in the construction of electrochemical sensors and biosensors along with other nanomaterials and conducting polymers.

Electrochemical non-enzymatic glucose sensors

International Nuclear Information System (INIS)

Park, Sejin; Boo, Hankil; Chung, Taek Dong

2006-01-01

The electrochemical determination of glucose concentration without using enzyme is one of the dreams that many researchers have been trying to make come true. As new materials have been reported and more knowledge on detailed mechanism of glucose oxidation has been unveiled, the non-enzymatic glucose sensor keeps coming closer to practical applications. Recent reports strongly imply that this progress will be accelerated in 'nanoera'. This article reviews the history of unraveling the mechanism of direct electrochemical oxidation of glucose and making attempts to develop successful electrochemical glucose sensors. The electrochemical oxidation of glucose molecules involves complex processes of adsorption, electron transfer, and subsequent chemical rearrangement, which are combined with the surface reactions on the metal surfaces. The information about the direct oxidation of glucose on solid-state surfaces as well as new electrode materials will lead us to possible breakthroughs in designing the enzymeless glucose sensing devices that realize innovative and powerful detection. An example of those is to introduce nanoporous platinum as an electrode, on which glucose is oxidized electrochemically with remarkable sensitivity and selectivity. Better model of such glucose sensors is sought by summarizing and revisiting the previous reports on the electrochemistry of glucose itself and new electrode materials

CuO nanoparticle sensor for the electrochemical determination of dopamine

International Nuclear Information System (INIS)

Reddy, Sathish; Kumara Swamy, B.E.; Jayadevappa, H.

2012-01-01

Highlights: ► The MCPE prepared from flake-shaped CuO nanoparticles exhibits good electrocatalytic activity for DA compared with MCPE prepared from rod-shaped CuO nanoparticles. ► The MCPE prepared from SDS/polyglycine/flake-shaped CuO nanoparticles strong electrocatalytic enhancement of redox peak currents for DA and large peak potential separation between E AA − E DA . ► Analysis of DA shows linearly increase in anodic peak current in presence of excess ascorbic acid. ► Ease of preparation and good analytical response supports its claim for use as a potential dopamine sensor. - Abstract: In the present work, different shaped CuO nanoparticles were synthesized using cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) in a co-precipitation method. The CuO nanoparticles were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared absorption spectroscopy (IR) and UV–visible absorption spectroscopy (UV–vis). The prepared CuO nanoparticles were used for the preparation of modified carbon-paste electrodes (MCPE) for the electrochemical detection of dopamine (DA) at pH 6.0. The MCPE prepared from flake-shaped CuO nanoparticles exhibited an enhanced current response for DA. Electrochemical parameters, such as the surface area of the electrode, the heterogeneous rate constant (k s ) and the lower detection limit (5.5 × 10 −8 M), were calculated and compared with those of the MCPE prepared from rod-shaped CuO nanoparticles. The MCPE prepared from SDS/polyglycine/flake-shaped CuO nanoparticles exhibited a further improved current response for DA and a high selectivity (E AA − E DA = 0.28 V) for the simultaneous investigation of DA and ascorbic acid (AA) at pH 6.0. The modified carbon-paste electrochemical sensors were compared, and the MCPE prepared from SDS/polyglycine/flake-shaped CuO nanoparticles exhibited better performance than the MCPE prepared from CTAB

Imprinted electrochemical sensor for dopamine recognition and determination based on a carbon nanotube/polypyrrole film

International Nuclear Information System (INIS)

Kan Xianwen; Zhou Hong; Li Chen; Zhu Anhong; Xing Zonglan; Zhao Zhe

2012-01-01

An electrochemical sensor combining a molecular imprinted technique and an electropolymerization method was developed in this work. A molecular imprinted polymer (MIP) film was fabricated by electropolymerizing pyrrole in the presence of dopamine (DA) after electrodepositing carboxyl-functionalized multi-walled carbon nanotubes (MWNTs-COOH) onto a glassy carbon electrode (GCE) surface. Scanning electron microscopy (SEM), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) were employed to characterize the constructed sensor. The effects of pH, the monomer concentration, the number of cycles for the electropolymerization, and the scan rate for the sensor preparation were optimized. The MIP-based sensor displayed an excellent recognition capacity toward DA compared with other structurally similar molecules. Additionally, the DPV peak current was linear to the DA concentration in the range from 6.25 × 10 −7 to 1 × 10 −4 mol/L, with a detection limit of 6 × 10 −8 mol/L. The prepared sensor also showed stable reproducibility and regeneration capacity.

MIP sensors--the electrochemical approach.

Science.gov (United States)

Malitesta, Cosimino; Mazzotta, Elisabetta; Picca, Rosaria A; Poma, Alessandro; Chianella, Iva; Piletsky, Sergey A

2012-02-01

This review highlights the importance of coupling molecular imprinting technology with methodology based on electrochemical techniques for the development of advanced sensing devices. In recent years, growing interest in molecularly imprinted polymers (MIPs) in the preparation of recognition elements has led researchers to design novel formats for improvement of MIP sensors. Among possible approaches proposed in the literature on this topic, we will focus on the electrosynthesis of MIPs and on less common hybrid technology (e.g. based on electrochemistry and classical MIPs, or nanotechnology). Starting from the early work reported in this field, an overview of the most innovative and successful examples will be reviewed.

Electrochemical and optical sugar sensors based on phenylboronic acid and its derivatives

Energy Technology Data Exchange (ETDEWEB)

Egawa, Yuya; Seki, Toshinobu [Faculty of Pharmaceutical Sciences, Josai University, Keyakidai, Sakado, Saitama 350-0295 (Japan); Takahashi, Shigehiro [Graduate School of Pharmaceutical Sciecnes, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578 (Japan); Anzai, Jun-ichi, E-mail: junanzai@mail.pharm.tohoku.ac.jp [Graduate School of Pharmaceutical Sciecnes, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578 (Japan)

2011-10-10

Recent progress in electrochemical and optical sugar sensors based on phenylboronic acid (PBA) and its derivatives as recognition components is reviewed. PBAs are known to bind diol compounds including sugars to form cyclic boronate esters that are negatively charged as a result of the addition of OH{sup -} ions from solution. Based on the formation of PBA charged species, sugars and their derivatives can be detected by means of electrochemical and optical techniques. For the development of PBA-based electrochemical sensing systems or sensors, PBA is modified with a redox-active marker, because PBA itself is electrochemically inactive, and ferrocene derivatives are often employed for this purpose. Ferrocene-modified PBAs have been used as redox-active additives in solution for the electrochemical detection of sugars and derivatives. PBA-modified electrodes have also been constructed as reagentless electrochemical sensors, where PBAs are immobilized on the surface of metal and carbon electrodes through mainly two routes: as a self-assembled monolayer film and as a polymer thin film. PBA-modified electrodes can be successfully used to detect sugars and derivatives through potentiometric and voltammetric responses. In addition, PBA-modified electrodes can be used for the immobilization of glycoenzymes on an electrode surface by the formation of boronate esters with carbohydrate chains in the glycoenzymes, thus resulting in enzyme biosensors. For the development of PBA-based optical sensors, a variety of chromophores and fluorophores have been coupled with PBA. Azobenzene dyes have been most frequently used for the preparation of colorimetric sugar sensors, in which the absorption wavelength and intensity of the dye are dependent on the type and concentration of added sugars. The sensitivity of the sensors is significantly improved based on multi-component systems in which alizalin red S, pyrocatechol violet, starch-iodine complex, and cyclodextrin are employed as

Electrochemical and optical sugar sensors based on phenylboronic acid and its derivatives

International Nuclear Information System (INIS)

Egawa, Yuya; Seki, Toshinobu; Takahashi, Shigehiro; Anzai, Jun-ichi

2011-01-01

Recent progress in electrochemical and optical sugar sensors based on phenylboronic acid (PBA) and its derivatives as recognition components is reviewed. PBAs are known to bind diol compounds including sugars to form cyclic boronate esters that are negatively charged as a result of the addition of OH - ions from solution. Based on the formation of PBA charged species, sugars and their derivatives can be detected by means of electrochemical and optical techniques. For the development of PBA-based electrochemical sensing systems or sensors, PBA is modified with a redox-active marker, because PBA itself is electrochemically inactive, and ferrocene derivatives are often employed for this purpose. Ferrocene-modified PBAs have been used as redox-active additives in solution for the electrochemical detection of sugars and derivatives. PBA-modified electrodes have also been constructed as reagentless electrochemical sensors, where PBAs are immobilized on the surface of metal and carbon electrodes through mainly two routes: as a self-assembled monolayer film and as a polymer thin film. PBA-modified electrodes can be successfully used to detect sugars and derivatives through potentiometric and voltammetric responses. In addition, PBA-modified electrodes can be used for the immobilization of glycoenzymes on an electrode surface by the formation of boronate esters with carbohydrate chains in the glycoenzymes, thus resulting in enzyme biosensors. For the development of PBA-based optical sensors, a variety of chromophores and fluorophores have been coupled with PBA. Azobenzene dyes have been most frequently used for the preparation of colorimetric sugar sensors, in which the absorption wavelength and intensity of the dye are dependent on the type and concentration of added sugars. The sensitivity of the sensors is significantly improved based on multi-component systems in which alizalin red S, pyrocatechol violet, starch-iodine complex, and cyclodextrin are employed as

Electrochemical Sensor Coating Based on Electrophoretic Deposition of Au-Doped Self-Assembled Nanoparticles.

Science.gov (United States)

Zhang, Rongli; Zhu, Ye; Huang, Jing; Xu, Sheng; Luo, Jing; Liu, Xiaoya

2018-02-14

The electrophoretic deposition (EPD) of self-assembled nanoparticles (NPs) on the surface of an electrode is a new strategy for preparing sensor coating. By simply changing the deposition conditions, the electrochemical response for an analyte of deposited NPs-based coating can be controlled. This advantage can decrease the difference between different batches of sensor coating and ensure the reproducibility of each sensor. This work investigated the effects of deposition conditions (including deposition voltage, pH value of suspension, and deposition time) on the structure and the electrochemical response for l-tryptophan of sensor coating formed from Au-doped poly(sodium γ-glutamate) with pendant dopamine units nanohybrids (Au/γ-PGA-DA NBs) via the EPD method. The structure and thickness of the deposited sensor coating were measured by atomic force microscopy, which demonstrated that the structure and thickness of coating can be affected by the deposition voltage, the pH value of the suspension, and the deposition time. The responsive current for l-tryptophan of the deposited sensor coating were measured by differential pulse voltammetry, which showed that the responsive current value was affected by the structure and thickness of the deposited coating. These arguments suggested that a rich design-space for tuning the electrochemical response for analyte and a source of variability in the structure of sensor coating can be provided by the deposition conditions. When Au/γ-PGA-DA NBs were deposited on the electrode surface and formed a continuous coating with particle morphology and thinner thickness, the deposited sensor coating exhibited optimal electrochemical response for l-tryptophan.

Cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode as electrochemical sensor on microfluidic chip

International Nuclear Information System (INIS)

Li Xinchun; Chen Zuanguang; Zhong Yuwen; Yang Fan; Pan Jianbin; Liang Yajing

2012-01-01

Highlights: ► CoHCF nanoparticles modified MWCNTs/graphite electrode use for electrochemistry on electrophoresis microchip for the first time. ► Simultaneous, rapid, and sensitive electrochemical detection of hydrazine and isoniazid in real samples. ► An exemplary work of CME sensor assembly onto microchip for determination of analytes with environmental significance. ► Manifestation of the applicability and flexibility of CME sensor for electroanalysis on microfluidic chip. - Abstract: Nanomaterial-based electrochemical sensor has received significant interest. In this work, cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode was electrochemically prepared and exploited as an amperometric detector for microchip electrophoresis. The prepared sensor displayed rapid and sensitive response towards hydrazine and isoniazid oxidation, which was attributed to synergetic electrocatalytic effect of cobalt hexacyanoferrate and multi-walled carbon nanotubes. The sensitivity enhancement with nearly two orders of magnitude was gained, compared with the bare carbon paste electrode, with the detection limit of 0.91 μM (S/N = 3) for hydrazine. Acceptable repeatability of the microanalysis system was verified by consecutive eleven injections of hydrazine without chip and electrode treatments, the RSDs for peak current and migration time were 3.4% and 2.1%, respectively. Meanwhile, well-shaped electrophoretic peaks were observed, mainly due to fast electron transfer of electroactive species on the modified electrode. The developed microchip-electrochemistry setup was successfully applied to the determination of hydrazine and isoniazid in river water and pharmaceutical preparation, respectively. Several merits of the novel electrochemical sensor coupled with microfluidic platform, such as comparative stability, easy fabrication and high sensitivity, hold great potential for hydrazine compounds assay in the lab-on-a-chip system.

Electrochemical sensors and biosensors based on redox polymer/carbon nanotube modified electrodes: a review.

Science.gov (United States)

Barsan, Madalina M; Ghica, M Emilia; Brett, Christopher M A

2015-06-30

The aim of this review is to present the contributions to the development of electrochemical sensors and biosensors based on polyphenazine or polytriphenylmethane redox polymers together with carbon nanotubes (CNT) during recent years. Phenazine polymers have been widely used in analytical applications due to their inherent charge transport properties and electrocatalytic effects. At the same time, since the first report on a CNT-based sensor, their application in the electroanalytical chemistry field has demonstrated that the unique structure and properties of CNT are ideal for the design of electrochemical (bio)sensors. We describe here that the specific combination of phenazine/triphenylmethane polymers with CNT leads to an improved performance of the resulting sensing devices, because of their complementary electrical, electrochemical and mechanical properties, and also due to synergistic effects. The preparation of polymer/CNT modified electrodes will be presented together with their electrochemical and surface characterization, with emphasis on the contribution of each component on the overall properties of the modified electrodes. Their importance in analytical chemistry is demonstrated by the numerous applications based on polymer/CNT-driven electrocatalytic effects, and their analytical performance as (bio) sensors is discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Electrochemical sensor for detection of carcinoma

International Nuclear Information System (INIS)

Thakur, Bhawana; Sawant, Shilpa N.; Jayakumar, S.

2012-01-01

Detection of carcinoma in early stage is very important for its effective treatment. Although considerable advancement has been made in its detection and treatment, there is a significant need for rapid, low-cost, sensitive, and selective biosensors for detection of cancer. In recent years, electrochemical detection techniques have received much attention due to their rapid response, high sensitivity, and inherent selectivity. They can provide an inexpensive platform for detection of analytes in clinical diagnostics. Conducting polymers are a versatile material for development of electrochemical biosensors. Due to the conducting nature of these polymers, they act as a transducer to convert the biological signal into electrical signal. These polymers also exhibit good biocompatibility, hence are ideal for immobilisation of biological recognition element during the development of the sensor film. Recently author have demonstrated a whole cell based electrochemical biosensor for detection of the pesticide Lindane at very low concentrations. In the present study, we have tried to develop polyaniline based electrochemical sensor for detection of carcinoma. Polyaniline was deposited on gold interdigitated electrodes by electropolymerization using potentiodynamic method. The polymer film was suitably modified to obtain the sensor film for recognition of the tumour cells. Response of the sensor to various tumour cells such as lung cancer cells, human fibrosarcoma cells, prostate cancer cells, breast cancer cells was studied and was compared to that of normal cells. The sensor electrode could detect tumour cells based on the nature of response obtained

Cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode as electrochemical sensor on microfluidic chip

Energy Technology Data Exchange (ETDEWEB)

Li Xinchun [School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road of Higher Education Mega Centre, Guangzhou 510006 (China); Chen Zuanguang, E-mail: chenzg@mail.sysu.edu.cn [School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road of Higher Education Mega Centre, Guangzhou 510006 (China); Zhong Yuwen, E-mail: yu0106@163.com [Center for Disease Control and Prevention of Guangdong Province, 176 Xingangxi, Guangzhou 510300 (China); Yang Fan; Pan Jianbin; Liang Yajing [School of Pharmaceutical Sciences, Sun Yat-sen University, 132 Waihuan East Road of Higher Education Mega Centre, Guangzhou 510006 (China)

2012-01-13

Highlights: Black-Right-Pointing-Pointer CoHCF nanoparticles modified MWCNTs/graphite electrode use for electrochemistry on electrophoresis microchip for the first time. Black-Right-Pointing-Pointer Simultaneous, rapid, and sensitive electrochemical detection of hydrazine and isoniazid in real samples. Black-Right-Pointing-Pointer An exemplary work of CME sensor assembly onto microchip for determination of analytes with environmental significance. Black-Right-Pointing-Pointer Manifestation of the applicability and flexibility of CME sensor for electroanalysis on microfluidic chip. - Abstract: Nanomaterial-based electrochemical sensor has received significant interest. In this work, cobalt hexacyanoferrate modified multi-walled carbon nanotubes/graphite composite electrode was electrochemically prepared and exploited as an amperometric detector for microchip electrophoresis. The prepared sensor displayed rapid and sensitive response towards hydrazine and isoniazid oxidation, which was attributed to synergetic electrocatalytic effect of cobalt hexacyanoferrate and multi-walled carbon nanotubes. The sensitivity enhancement with nearly two orders of magnitude was gained, compared with the bare carbon paste electrode, with the detection limit of 0.91 {mu}M (S/N = 3) for hydrazine. Acceptable repeatability of the microanalysis system was verified by consecutive eleven injections of hydrazine without chip and electrode treatments, the RSDs for peak current and migration time were 3.4% and 2.1%, respectively. Meanwhile, well-shaped electrophoretic peaks were observed, mainly due to fast electron transfer of electroactive species on the modified electrode. The developed microchip-electrochemistry setup was successfully applied to the determination of hydrazine and isoniazid in river water and pharmaceutical preparation, respectively. Several merits of the novel electrochemical sensor coupled with microfluidic platform, such as comparative stability, easy fabrication and

Electrochemical sensors and biosensors based on less aggregated graphene.

Science.gov (United States)

Bo, Xiangjie; Zhou, Ming; Guo, Liping

2017-03-15

As a novel single-atom-thick sheet of sp 2 hybridized carbon atoms, graphene (GR) has attracted extensive attention in recent years because of its unique and remarkable properties, such as excellent electrical conductivity, large theoretical specific surface area, and strong mechanical strength. However, due to the π-π interaction, GR sheets are inclined to stack together, which may seriously degrade the performance of GR with the unique single-atom layer. In recent years, an increasing number of GR-based electrochemical sensors and biosensors are reported, which may reflect that GR has been considered as a kind of hot and promising electrode material for electrochemical sensor and biosensor construction. However, the active sites on GR surface induced by the irreversible GR aggregations would be deeply secluded inside the stacked GR sheets and therefore are not available for the electrocatalysis. So the alleviation or the minimization of the aggregation level for GR sheets would facilitate the exposure of active sites on GR and effectively upgrade the performance of GR-based electrochemical sensors and biosensors. Less aggregated GR with low aggregation and high dispersed structure can be used in improving the electrochemical activity of GR-based electrochemical sensors or biosensors. In this review, we summarize recent advances and new progress for the development of electrochemical sensors based on less aggregated GR. To achieve such goal, many strategies (such as the intercalation of carbon materials, surface modification, and structural engineering) have been applied to alleviate the aggregation level of GR in order to enhance the performance of GR-based electrochemical sensors and biosensors. Finally, the challenges associated with less aggregated GR-based electrochemical sensors and biosensors as well as related future research directions are discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

A Highly Sensitive Electrochemical Glucose Sensor By Nickel-Epoxy Electrode With Non-Enzymatic Sensor

Directory of Open Access Journals (Sweden)

Riyanto Riyanto

2016-03-01

Full Text Available The preparation of new sensor for glucose was based on the fact that glucose can be determined by non-enzymatic glucose oxidase. The Ni metals (99.98% purity, 0.5 mm thick, Aldrich Chemical Company was used to prepare Ni-Epoxy electrode. The Ni-epoxy electrodes were prepared in square cut of 1 cm and 1 mm by length and wide respectively. The Ni metal electrodes were connected to silver wire with silver conducting paint prior covered with epoxy gum. The prepared of nickel-epoxy modified electrode showed outstanding electro catalytic activity toward the oxidation of glucose in alkaline solution. The result from this research are correlation of determination using Nickel-Epoxyelectrode for electroanalysis of glucose in NaOH was R2 = 0.9984. LOQ, LOD and recovery of the Nickel-Epoxy electrode towards glucose were found to be 4.4 μM, 1.48 μM and 98.19%, respectively. The Nickel-Epoxy wire based electrochemical glucose sensor demonstrates good sensitivity, wide linear range, outstanding detection limit, attractive selectivity, good reproducibility, high stability as well as prominent feasibility use of non-enzymatic sensor for monitoring glucose in human urine owing to its advantages of low cost, simple preparation and excellent properties for glucose detection.

Development of electrochemical sensor for the determination of toxic gases

International Nuclear Information System (INIS)

Ahmed, R.

1997-01-01

Monitoring release of flue and toxic gases and vapours of volatile organic toxic substances into the atmosphere is one of the most important problems in environmental pollution control studies particularly in industrial installations in order to avoid poisoning and other health hazards. In industrial areas continuous monitoring of toxic gases and vapours is required for the safety of workers and for this purpose different types of sensors and available such as thermal sensors mass sensors, biosensors, optical sensors and electrochemical sensors. Among all of these sensors electrochemical sensors are most cost-effective, accurate and very good for continuous monitoring. They can be categorized into potentiometric, conductometric, amperometric and voltammetric sensors. Applications of different types of electrochemical sensors are briefly reviewed. Development of polymer membrane and conducting polymers are most important for fabrication of electrochemical sensors, which can analyse up to twenty two gases and vapours simultaneously. Some of the commercially used electrochemical sensors are described. For the determination of hydrogen sulfide an electrochemical sensor was developed. Teflon based conduction polymer membrane was treated with some electrolytes and then silver metal was deposited on one side of the membrane. Metal part side was exposed to gases and the other side was deposited on one side of the membrane metal part side was exposed to gasses and the other side was connected with two electrodes including reference and counter electrodes, whereas metal part acted as working electrode. This system can also me used for the analysis of their gases like SO/sub 2/ etc; because they react at different potentials with the metal to generate the signals. (author)

All-Polymer Electrochemical Sensors

DEFF Research Database (Denmark)

Kafka, Jan Robert

This thesis presents fabrication strategies to produce different types of all-polymer electrochemical sensors based on electrodes made of the highly conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT). Three different systems are presented, fabricated either by using microdrilling or by hot...

Electrochemical Biosensors - Sensor Principles and Architectures

Science.gov (United States)

Grieshaber, Dorothee; MacKenzie, Robert; Vörös, Janos; Reimhult, Erik

2008-01-01

Quantification of biological or biochemical processes are of utmost importance for medical, biological and biotechnological applications. However, converting the biological information to an easily processed electronic signal is challenging due to the complexity of connecting an electronic device directly to a biological environment. Electrochemical biosensors provide an attractive means to analyze the content of a biological sample due to the direct conversion of a biological event to an electronic signal. Over the past decades several sensing concepts and related devices have been developed. In this review, the most common traditional techniques, such as cyclic voltammetry, chronoamperometry, chronopotentiometry, impedance spectroscopy, and various field-effect transistor based methods are presented along with selected promising novel approaches, such as nanowire or magnetic nanoparticle-based biosensing. Additional measurement techniques, which have been shown useful in combination with electrochemical detection, are also summarized, such as the electrochemical versions of surface plasmon resonance, optical waveguide lightmode spectroscopy, ellipsometry, quartz crystal microbalance, and scanning probe microscopy. The signal transduction and the general performance of electrochemical sensors are often determined by the surface architectures that connect the sensing element to the biological sample at the nanometer scale. The most common surface modification techniques, the various electrochemical transduction mechanisms, and the choice of the recognition receptor molecules all influence the ultimate sensitivity of the sensor. New nanotechnology-based approaches, such as the use of engineered ion-channels in lipid bilayers, the encapsulation of enzymes into vesicles, polymersomes, or polyelectrolyte capsules provide additional possibilities for signal amplification. In particular, this review highlights the importance of the precise control over the delicate

Electrochemical bisphenol A sensor based on N-doped graphene sheets

International Nuclear Information System (INIS)

Fan Haixia; Li Yan; Wu Dan; Ma Hongmin; Mao Kexia; Fan Dawei; Du Bin; Li He; Wei Qin

2012-01-01

Highlights: ► N-doped graphene sheets have catalytic activity towards the BPA oxidation. ► The biosensor based on N-doped graphene sheets and chitosan. ► This method was proposed for determination of BPA utilizing N-doped graphene sheets. - Abstract: Bisphenol A (BPA), which could disrupt endocrine system and cause cancer, has been considered as an endocrine disruptor. Therefore, it is very important and necessary to develop a sensitive and selective method for detection of BPA. Herein, nitrogen-doped graphene sheets (N-GS) and chitosan (CS) were used to prepare electrochemical BPA sensor. Compared with graphene, N-GS has favorable electron transfer ability and electrocatalytic property, which could enhance the response signal towards BPA. CS also exhibits excellent film forming ability and improves the electrochemical behavior of N-GS modified electrode. The sensor exhibits a sensitive response to BPA in the range of 1.0 × 10 −8 –1.3 × 10 −6 mol L −1 with a low detection limit of 5.0 × 10 −9 mol L −1 under the optimal conditions. Finally, this proposed sensor was successfully employed to determine BPA in water samples with satisfactory results.

Electrochemical sensors based on polyconjugated conducting polymers

Energy Technology Data Exchange (ETDEWEB)

Zotti, G. (Ist. di Polarografia ed Elettrochimica Preparativa, Consiglio Nazionale delle Ricerche, Padua (Italy))

1992-09-01

An overview of the applications of polyconjugated conducting polymers to electrochemical sensors is given. Gas sensors, ion sensors, and biosensors (non-enzyme and enzyme sensors) are presented and discussed. The role of the polymer as enzyme host and mediator of charge transfer is particularly emphasized in the light of recent results. (orig.).

Nanomaterials-based electrochemical sensors for nitric oxide

International Nuclear Information System (INIS)

Dang, Xueping; Hu, Hui; Wang, Shengfu; Hu, Shengshui

2015-01-01

Electrochemical sensing has been demonstrated to represent an efficient way to quantify nitric oxide (NO) in challenging physiological environments. A sensing interface based on nanomaterials opens up new opportunities and broader prospects for electrochemical NO sensors. This review (with 141 refs.) gives a general view of recent advances in the development of electrochemical sensors based on nanomaterials. It is subdivided into sections on (i) carbon derived nanomaterials (such as carbon nanotubes, graphenes, fullerenes), (ii) metal nanoparticles (including gold, platinum and other metallic nanoparticles); (iii) semiconductor metal oxide nanomaterials (including the oxides of titanium, aluminum, iron, and ruthenium); and finally (iv) nanocomposites (such as those formed from carbon nanomaterials with nanoparticles of gold, platinum, NiO or TiO 2 ). The various strategies are discussed, and the advances of using nanomaterials and the trends in NO sensor technology are outlooked in the final section. (author)

Copper-based electrochemical sensor with palladium electrode for cathodic stripping voltammetry of manganese.

Science.gov (United States)

Kang, Wenjing; Pei, Xing; Bange, Adam; Haynes, Erin N; Heineman, William R; Papautsky, Ian

2014-12-16

In this work, we report on the development of a palladium-based, microfabricated point-of-care electrochemical sensor for the determination of manganese using square wave cathodic stripping voltammetry. Heavy metals require careful monitoring, yet current methods are too complex for a point-of-care system. Voltammetry offers an attractive approach to metal detection on the microscale, but traditional carbon, gold, or platinum electrodes are difficult or expensive to microfabricate, preventing widespread use. Our sensor uses palladium working and auxiliary electrodes and integrates them with a copper-based reference electrode for simple fabrication and compatibility with microfabrication and printed circuit board processing, while maintaining competitive performance in electrochemical detection. Copper electrodes were prepared on glass substrate using a combination of microfabrication procedures followed by electrodeposition of palladium. The disposable sensor system was formed by bonding a poly(dimethylsiloxane) (PDMS) well to the glass substrate. Cathodic stripping voltammetry of manganese using our new disposable palladium-based sensors exhibited 334 nM (18.3 ppb) limit of detection in borate buffer. The sensor was used to demonstrate manganese determination in natural water samples from a pond in Burnet Woods, located in Cincinnati, OH, and the Ohio River.

Ultrasensitive molecularly imprinted electrochemical sensor based on magnetism graphene oxide/β-cyclodextrin/Au nanoparticles composites for chrysoidine analysis

International Nuclear Information System (INIS)

Wang, Xiaojiao; Li, Xiangjun; Luo, Chuannan; Sun, Min; Li, Leilei; Duan, Huimin

2014-01-01

Highlights: • Synthesis and application of MGO/β-CD@AuNPs as a sensor for chrysoidine analysis. • The synthesized polymer had a laminar structure with high surface. • The propose sensor showed high selectivity and good sensitivity. - Abstract: A imprinted electrochemical sensor based on glassy carbon electrode (GCE) for ultrasensitive detection of chrysoidine was fabricated. A GCE was modified by magnetic graphene oxide/β-cyclodextrin/gold nanoparticles composites (MGO/β-CD@AuNPs). The sensing surface area and electronic transmission rate were increased, which was benefited from the distribution property of MGO/β-CD@AuNPs. The MGO/β-CD@AuNPs composite improved electrochemical response and sensitivity of the sensor. The molecularly imprinted electrochemical sensor was prepared by electropolymerization on modified electrode. Chrysoidine and pyrrole were used as template molecule and functional monomer, respectively. Under the optimization experimental conditions, the electrochemical sensor exhibited excellent analytical performance: the detection of chrysoidine ranged from 5.0 × 10 −8 mol/L to 5.0 × 10 −6 mol/L with the detection limit of 1.7 × 10 −8 mol/L. The sensor was applied to determine chrysoidine in spiked water samples and showed high selectivity, good sensitivity and acceptable reproducibility. The proposed method provides a promising platform for trace amount detection of other food additives

Estrone specific molecularly imprinted polymeric nanospheres: synthesis, characterization and applications for electrochemical sensor development.

Science.gov (United States)

Congur, Gulsah; Senay, Hilal; Turkcan, Ceren; Canavar, Ece; Erdem, Arzum; Akgol, Sinan

2013-06-28

The aim of this study is (i) to prepare estrone-imprinted nanospheres (nano-EST-MIPs) and (ii) to integrate them into the electrochemical sensor as a recognition layer. N-methacryloyl-(l)-phenylalanine (MAPA) was chosen as the complexing monomer. Firstly, estrone (EST) was complexed with MAPA and the EST-imprinted poly(2-hyroxyethylmethacrylate-co-N-methacryloyl-(l)-phenylalanine) [EST-imprinted poly(HEMA-MAPA)] nanospheres were synthesized by surfactant- free emulsion polymerization method. The specific surface area of the EST-imprinted poly(HEMA-MAPA) nanospheres was found to be 1275 m2/g with a size of 163.2 nm in diameter. According to the elemental analysis results, the nanospheres contained 95.3 mmole MAPA/g nanosphere. The application of EST specific MIP nanospheres for the development of an electrochemical biosensor was introduced for the first time in our study by using electrochemical impedance spectroscopy (EIS) technique. This nano-MIP based sensor presented a great specificity and selectivity for EST.

Recent Progress in Electrochemical HbA1c Sensors: A Review

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Baozhen Wang

2015-03-01

Full Text Available This article reviews recent progress made in the development of electrochemical glycated hemoglobin (HbA1c sensors for the diagnosis and management of diabetes mellitus. Electrochemical HbA1c sensors are divided into two categories based on the detection protocol of the sensors. The first type of sensor directly detects HbA1c by binding HbA1c on the surface of an electrode through bio-affinity of antibody and boronic acids, followed by an appropriate mode of signal transduction. In the second type of sensor, HbA1c is indirectly determined by detecting a digestion product of HbA1c, fructosyl valine (FV. Thus, the former sensors rely on the selective binding of HbA1c to the surface of the electrodes followed by electrochemical signaling in amperometric, voltammetric, impedometric, or potentiometric mode. Redox active markers, such as ferrocene derivatives and ferricyanide/ferrocyanide ions, are often used for electrochemical signaling. For the latter sensors, HbA1c must be digested in advance by proteolytic enzymes to produce the FV fragment. FV is electrochemically detected through catalytic oxidation by fructosyl amine oxidase or by selective binding to imprinted polymers. The performance characteristics of HbA1c sensors are discussed in relation to their use in the diagnosis and control of diabetic mellitus.

Disposable Screen Printed Electrochemical Sensors: Tools for Environmental Monitoring

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Akhtar Hayat

2014-06-01

Full Text Available Screen printing technology is a widely used technique for the fabrication of electrochemical sensors. This methodology is likely to underpin the progressive drive towards miniaturized, sensitive and portable devices, and has already established its route from “lab-to-market” for a plethora of sensors. The application of these sensors for analysis of environmental samples has been the major focus of research in this field. As a consequence, this work will focus on recent important advances in the design and fabrication of disposable screen printed sensors for the electrochemical detection of environmental contaminants. Special emphasis is given on sensor fabrication methodology, operating details and performance characteristics for environmental applications.

Determination of ascorbic acid, dopamine, and uric acid by a novel electrochemical sensor based on pristine graphene

International Nuclear Information System (INIS)

Qi, Shaopeng; Zhao, Bo; Tang, Heqing; Jiang, Xiaoqing

2015-01-01

In this article, a novel electrochemical sensor based on pristine graphene (PG) is successfully constructed to detect ascorbic acid (AA), dopamine (DA), and uric acid (UA). The PG is obtained by liquid-phase exfoliation of graphite and characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. The sensor based on PG prepared by this method to realize simultaneous determination of AA, DA, and UA is firstly reported. The linear detection ranges for AA, DA, and UA are 9.00–2314 μM, 5.00–710 μM, and 6.00–1330 μM, respectively, with detection limits of 6.45, 2.00, and 4.82 μM. This PG based sensor exhibits excellent performance for detection of AA, DA, and UA, which is much better than those electrochemical sensors based on chemical converted graphene

Integration of reconfigurable potentiometric electrochemical sensors into a digital microfluidic platform.

Science.gov (United States)

Farzbod, Ali; Moon, Hyejin

2018-05-30

This paper presents the demonstration of on-chip fabrication of a potassium-selective sensor array enabled by electrowetting on dielectric digital microfluidics for the first time. This demonstration proves the concept that electrochemical sensors can be seamlessly integrated with sample preparation units in a digital microfluidic platform. More significantly, the successful on-chip fabrication of a sensor array indicates that sensors become reconfigurable and have longer lifetime in a digital microfluidic platform. The on-chip fabrication of ion-selective electrodes includes electroplating Ag followed by forming AgCl layer by chemical oxidation and depositing a thin layer of desired polymer-based ion selective membrane on one of the sensor electrodes. In this study, potassium ionophores work as potassium ion channels and make the membrane selective to potassium ions. This selectiveness results in the voltage difference across the membrane layer, which is correlated with potassium ion concentration. The calibration curve of the fabricated potassium-selective electrode demonstrates the slope of 58 mV/dec for potassium concentration in KCl sample solutions and shows good agreement with the ideal Nernstian response. The proposed sensor platform is an outstanding candidate for a portable home-use for continuous monitoring of ions thanks to its advantages such as easy automation of sample preparation and detection processes, elongated sensor lifetime, minimal membrane and sample consumption, and user-definable/reconfigurable sensor array. Copyright © 2018 Elsevier B.V. All rights reserved.

Electrochemical, morphological and microstructural characterization of carbon film resistor electrodes for application in electrochemical sensors

International Nuclear Information System (INIS)

Gouveia-Caridade, Carla; Soares, David M.; Liess, Hans-Dieter; Brett, Christopher M.A.

2008-01-01

The electrochemical and microstructural properties of carbon film electrodes made from carbon film electrical resistors of 1.5, 15, 140 Ω and 2.0 kΩ nominal resistance have been investigated before and after electrochemical pre-treatment at +0.9 V vs SCE, in order to assess the potential use of these carbon film electrodes as electrochemical sensors and as substrates for sensors and biosensors. The results obtained are compared with those at electrodes made from previously investigated 2 Ω carbon film resistors. Cyclic voltammetry was performed in acetate buffer and phosphate buffer saline electrolytes and the kinetic parameters of the model redox system Fe(CN) 6 3-/4- obtained. The 1.5 Ω resistor electrodes show the best properties for sensor development with wide potential windows, similar electrochemical behaviour to those of 2 Ω and close-to-reversible kinetic parameters after electrochemical pre-treatment. The 15 and 140 Ω resistor electrodes show wide potential windows although with slower kinetics, whereas the 2.0 kΩ resistor electrodes show poor cyclic voltammetric profiles even after pre-treatment. Electrochemical impedance spectroscopy related these findings to the interfacial properties of the electrodes. Microstructural and morphological studies were carried out using contact mode Atomic Force Microscopy (AFM), Confocal Raman spectroscopy and X-ray diffraction. AFM showed more homogeneity of the films with lower nominal resistances, related to better electrochemical characteristics. X-ray diffraction and Confocal Raman spectroscopy indicate the existence of a graphitic structure in the carbon films

Electrochemical Biosensors - Sensor Principles and Architectures

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Erik Reimhult

2008-03-01

Full Text Available Quantification of biological or biochemical processes are of utmost importancefor medical, biological and biotechnological applications. However, converting the biologicalinformation to an easily processed electronic signal is challenging due to the complexity ofconnecting an electronic device directly to a biological environment. Electrochemical biosensorsprovide an attractive means to analyze the content of a biological sample due to thedirect conversion of a biological event to an electronic signal. Over the past decades severalsensing concepts and related devices have been developed. In this review, the most commontraditional techniques, such as cyclic voltammetry, chronoamperometry, chronopotentiometry,impedance spectroscopy, and various field-effect transistor based methods are presented alongwith selected promising novel approaches, such as nanowire or magnetic nanoparticle-basedbiosensing. Additional measurement techniques, which have been shown useful in combinationwith electrochemical detection, are also summarized, such as the electrochemical versionsof surface plasmon resonance, optical waveguide lightmode spectroscopy, ellipsometry,quartz crystal microbalance, and scanning probe microscopy.The signal transduction and the general performance of electrochemical sensors are often determinedby the surface architectures that connect the sensing element to the biological sampleat the nanometer scale. The most common surface modification techniques, the various electrochemicaltransduction mechanisms, and the choice of the recognition receptor moleculesall influence the ultimate sensitivity of the sensor. New nanotechnology-based approaches,such as the use of engineered ion-channels in lipid bilayers, the encapsulation of enzymesinto vesicles, polymersomes, or polyelectrolyte capsules provide additional possibilities forsignal amplification.In particular, this review highlights the importance of the precise control over the

Validation method for determination of cholesterol in human urine with electrochemical sensors using gold electrodes

Science.gov (United States)

Riyanto, Laksono, Tomy Agung

2017-12-01

Electrochemical sensors for the determination of cholesterol with Au as a working electrode (Au) and its application to the analysis of urine have been done. The gold electrode was prepared using gold pure (99.99%), with size 1.0 mm by length and wide respectively, connected with silver wire using silver conductive paint. Validation methods have been investigated in the analysis of cholesterol in human urine using electrochemical sensors or cyclic voltammetry (CV) method. The effect of electrolyte and uric acid concentration has been determined to produce the optimum method. Validation method parameters for cholesterol analysis in human urine using CV are precision, recovery, linearity, limit of detection (LOD) and limit of quantification (LOQ). The result showed the correlation of concentration of cholesterol to anodic peak current is the coefficient determination of R2 = 0.916. The results of the validation method showed the precision, recovery, linearity, LOD, and LOQ are 1.2539%, 144.33%, 0.916, 1.49 × 10-1 mM and 4.96 × 10-1 mM, respectively. As a conclusion is Au electrode is a good electrode for electrochemical sensors to determination of cholesterol in human urine.

Thermal Annealing Effect on Structural, Morphological, and Sensor Performance of PANI-Ag-Fe Based Electrochemical E. coli Sensor for Environmental Monitoring

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Norshafadzila Mohammad Naim

2015-01-01

Full Text Available PANI-Ag-Fe nanocomposite thin films based electrochemical E. coli sensor was developed with thermal annealing. PANI-Ag-Fe nanocomposite thin films were prepared by oxidative polymerization of aniline and the reduction process of Ag-Fe bimetallic compound with the presence of nitric acid and PVA. The films were deposited on glass substrate using spin-coating technique before they were annealed at 300°C. The films were characterized using XRD, UV-Vis spectroscopy, and FESEM to study the structural and morphological properties. The electrochemical sensor performance was conducted using I-V measurement electrochemical impedance spectroscopy (EIS. The sensitivity upon the presence of E. coli was measured in clean water and E. coli solution. From XRD analysis, the crystallite sizes were found to become larger for the samples after annealing. UV-Vis absorption bands for samples before and after annealing show maximum absorbance peaks at around 422 nm–424 nm and 426 nm–464 nm, respectively. FESEM images show the diameter size for nanospherical Ag-Fe alloy particles increases after annealing. The sensor performance of PANI-Ag-Fe nanocomposite thin films upon E. coli cells in liquid medium indicates the sensitivity increases after annealing.

Development and characterization of an electrochemical sensor for furosemide detection based on electropolymerized molecularly imprinted polymer.

Science.gov (United States)

Kor, Kamalodin; Zarei, Kobra

2016-01-01

A novel electrochemical sensor based on a molecularly imprinted polymer, poly(o-phenylenediamine) (PoPD), has been developed for selective and sensitive detection of furosemide. The sensor was prepared by incorporating of furosemide as template molecules during the electropolymerization of o-phenylenediamine on a gold electrode. To develop the molecularly imprinted polymer (MIP), the template molecules were removed from the modified electrode's surface by washing it with 0.25 mol L(-1) NaOH solution. The imprinted layer was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). The sensor's preparation conditions including furosemide concentration, the number of CV cycles in the electropolymerization process, extraction solution of the template from the imprinted film, the incubation time and the pH level were optimized. The incubation of the MIP-modified electrode, with respect to furosemide concentration, resulted in a suppression of the K4[Fe(CN)6] oxidation process. Under the optimal experimental conditions, the response of the imprinted sensor was linear in the range of 1.0×10(-7)-7.0×10(-6) mol L(-1) of furosemide. The detection limit was obtained as 7.0×10(-8) mol L(-1) for furosemide by using this sensor. The sensor was successfully used to determine the furosemide amount in the tablet and in human urine samples with satisfactory results. Copyright © 2015 Elsevier B.V. All rights reserved.

Environmental analysis by electrochemical sensors and biosensors fundamentals

CERN Document Server

Moretto, Ligia Maria

2014-01-01

This book presents an exhaustive overview of electrochemical sensors and biosensors for the analysis and monitoring of the most important analytes in the environmental field, in industry, in treatment plants and in environmental research. The chapters give the reader a comprehensive, state-of-the-art picture of the field of electrochemical sensors suitable to environmental analytes, from the theoretical principles of their design to their implementation, realization and application. The first three chapters discuss fundamentals, and the last three chapters cover the main groups of analytes of environmental interest.

Electrochemical DNA Hybridization Sensors Based on Conducting Polymers

Science.gov (United States)

Rahman, Md. Mahbubur; Li, Xiao-Bo; Lopa, Nasrin Siraj; Ahn, Sang Jung; Lee, Jae-Joon

2015-01-01

Conducting polymers (CPs) are a group of polymeric materials that have attracted considerable attention because of their unique electronic, chemical, and biochemical properties. This is reflected in their use in a wide range of potential applications, including light-emitting diodes, anti-static coating, electrochromic materials, solar cells, chemical sensors, biosensors, and drug-release systems. Electrochemical DNA sensors based on CPs can be used in numerous areas related to human health. This review summarizes the recent progress made in the development and use of CP-based electrochemical DNA hybridization sensors. We discuss the distinct properties of CPs with respect to their use in the immobilization of probe DNA on electrode surfaces, and we describe the immobilization techniques used for developing DNA hybridization sensors together with the various transduction methods employed. In the concluding part of this review, we present some of the challenges faced in the use of CP-based DNA hybridization sensors, as well as a future perspective. PMID:25664436

Electrochemical DNA Hybridization Sensors Based on Conducting Polymers

Directory of Open Access Journals (Sweden)

Md. Mahbubur Rahman

2015-02-01

Full Text Available Conducting polymers (CPs are a group of polymeric materials that have attracted considerable attention because of their unique electronic, chemical, and biochemical properties. This is reflected in their use in a wide range of potential applications, including light-emitting diodes, anti-static coating, electrochromic materials, solar cells, chemical sensors, biosensors, and drug-release systems. Electrochemical DNA sensors based on CPs can be used in numerous areas related to human health. This review summarizes the recent progress made in the development and use of CP-based electrochemical DNA hybridization sensors. We discuss the distinct properties of CPs with respect to their use in the immobilization of probe DNA on electrode surfaces, and we describe the immobilization techniques used for developing DNA hybridization sensors together with the various transduction methods employed. In the concluding part of this review, we present some of the challenges faced in the use of CP-based DNA hybridization sensors, as well as a future perspective.

Distributed electrochemical sensors: recent advances and barriers to market adoption.

Science.gov (United States)

Hoekstra, Rafael; Blondeau, Pascal; Andrade, Francisco J

2018-07-01

Despite predictions of their widespread application in healthcare and environmental monitoring, electrochemical sensors are yet to be distributed at scale, instead remaining largely confined to R&D labs. This contrasts sharply with the situation for physical sensors, which are now ubiquitous and seamlessly embedded in the mature ecosystem provided by electronics and connectivity protocols. Although chemical sensors could be integrated into the same ecosystem, there are fundamental issues with these sensors in the three key areas of analytical performance, usability, and affordability. Nevertheless, advances are being made in each of these fields, leading to hope that the deployment of automated and user-friendly low-cost electrochemical sensors is on the horizon. Here, we present a brief survey of key challenges and advances in the development of distributed electrochemical sensors for liquid samples, geared towards applications in healthcare and wellbeing, environmental monitoring, and homeland security. As will be seen, in many cases the analytical performance of the sensor is acceptable; it is usability that is the major barrier to commercial viability at this moment. Were this to be overcome, the issue of affordability could be addressed. Graphical Abstract ᅟ.

Novel membrane-based electrochemical sensor for real-time bio-applications

DEFF Research Database (Denmark)

Al Atraktchi, Fatima Al-Zahraa; Bakmand, Tanya; Dimaki, Maria

2014-01-01

This article presents a novel membrane-based sensor for real-time electrochemical investigations of cellular- or tissue cultures. The membrane sensor enables recording of electrical signals from a cell culture without any signal dilution, thus avoiding loss of sensitivity. Moreover, the porosity...... of the membrane provides optimal culturing conditions similar to existing culturing techniques allowing more efficient nutrient uptake and molecule release. The patterned sensor electrodes were fabricated on a porous membrane by electron-beam evaporation. The electrochemical performance of the membrane electrodes...

Electrochemical preparation of poly(methylene blue)/graphene nanocomposite thin films

International Nuclear Information System (INIS)

Erçarıkcı, Elif; Dağcı, Kader; Topçu, Ezgi; Alanyalıoğlu, Murat

2014-01-01

Highlights: • Poly(MB)/graphene thin films are prepared by a simple electrochemical approach. • Graphene layers in the film show a broad band in visible region of absorbance spectra. • Morphology of composite films indicates both disordered and ordered regions. • XRD reveals that nanocomposite films include rGO layers after electropolymerization process. • Chemically prepared graphene is better than electrochemically prepared graphene for electrooxidation of nitrite. - Abstract: Poly(methylene blue)/graphene nanocomposite thin films were prepared by electropolymerization of methylene blue in the presence of graphene which have been synthesized by two different methods of a chemical oxidation process and an electrochemical approach. Synthesized nanocomposite thin films were characterized by using cyclic voltammetry, UV–vis. absorption spectroscopy, powder X-ray diffraction, and scanning tunneling microscopy techniques. Electrocatalytical properties of prepared poly(methylene blue)/graphene nanocomposite films were compared toward electrochemical oxidation of nitrite. Under optimized conditions, electrocatalytical effect of nanocomposite films of chemically prepared graphene through electrochemical oxidation of nitrite was better than that of electrochemically prepared graphene

Electrochemical Performance of a Carbon Nanotube/La-Doped TiO2 Nanocomposite and its Use for Preparation of an Electrochemical Nicotinic Acid Sensor

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Hanxing Liu

2008-11-01

Full Text Available A carbon nanotube/La-doped TiO2 (La-TiO2 nanocomposite (CLTN was prepared by a procedure similar to a complex/adsorption process. Scanning electron microscopy (SEM images show that the La-TiO2 distributes on the carbon nanotube walls. The CLTN was mixed with paraffin to form a CLTN paste for the CLTN paste electrode (CLTNPE. The electrochemical characteristics of CLTNPE were compared with that of conventional carbon electrodes such as the carbon paste electrode (CPE and glass carbon electrode (GC. The CLTNPE exhibits electrochemical activity and was used to investigate the electrochemistry of nicotinic acid (NA. The modified electrode has a strong electrocatalytic effect on the redox of NA. The cyclic voltammetry (CV redox potential of NA at the CLTNPE is 320 mV. The oxidation process of NA on the CLTNPE is pH dependent. A sensitive chronoamperometric response for NA was obtained covering a linear range from 1.0×10-6 mol·L-1 to 1.2×10-4 mol·L-1, with a detection limit of 2.7×10-7 mol·L-1. The NA sensor displays a remarkable sensitivity and stability. The mean recovery of NA in the human urine is 101.8%, with a mean variation coefficient (RSD of 2.6%.

Woven electrochemical fabric-based test sensors (WEFTS): a new class of multiplexed electrochemical sensors.

Science.gov (United States)

Choudhary, Tripurari; Rajamanickam, G P; Dendukuri, Dhananjaya

2015-05-07

We present textile weaving as a new technique for the manufacture of miniature electrochemical sensors with significant advantages over current fabrication techniques. Biocompatible silk yarn is used as the material for fabrication instead of plastics and ceramics used in commercial sensors. Silk yarns are coated with conducting inks and reagents before being handloom-woven as electrodes into patches of fabric to create arrays of sensors, which are then laminated, cut and packaged into individual sensors. Unlike the conventionally used screen-printing, which results in wastage of reagents, yarn coating uses only as much reagent and ink as required. Hydrophilic and hydrophobic yarns are used for patterning so that sample flow is restricted to a small area of the sensor. This simple fluidic control is achieved with readily available materials. We have fabricated and validated individual sensors for glucose and hemoglobin and a multiplexed sensor, which can detect both analytes. Chronoamperometry and differential pulse voltammetry (DPV) were used to detect glucose and hemoglobin, respectively. Industrial quantities of these sensors can be fabricated at distributed locations in the developing world using existing skills and manufacturing facilities. We believe such sensors could find applications in the emerging area of wearable sensors for chemical testing.

Recent Progress in Electrochemical Biosensors for Glycoproteins

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Uichi Akiba

2016-12-01

Full Text Available This review provides an overview of recent progress in the development of electrochemical biosensors for glycoproteins. Electrochemical glycoprotein sensors are constructed by combining metal and carbon electrodes with glycoprotein-selective binding elements including antibodies, lectin, phenylboronic acid and molecularly imprinted polymers. A recent trend in the preparation of glycoprotein sensors is the successful use of nanomaterials such as graphene, carbon nanotube, and metal nanoparticles. These nanomaterials are extremely useful for improving the sensitivity of glycoprotein sensors. This review focuses mainly on the protocols for the preparation of glycoprotein sensors and the materials used. Recent improvements in glycoprotein sensors are discussed by grouping the sensors into several categories based on the materials used as recognition elements.

Synthesis of new copper nanoparticle-decorated anchored type ligands: Applications as non-enzymatic electrochemical sensors for hydrogen peroxide

Energy Technology Data Exchange (ETDEWEB)

Ensafi, Ali A., E-mail: Ensafi@cc.iut.ac.ir; Zandi-Atashbar, N.; Ghiaci, M.; Taghizadeh, M.; Rezaei, B.

2015-02-01

In this work, copper nanoparticles (CuNPs) decorated on two new anchored type ligands were utilized to prepare two electrochemical sensors. These ligands are made from bonding amine chains to silica support including SiO{sub 2}–pro–NH{sub 2} (compound I) and SiO{sub 2}–pro–NH–cyanuric–NH{sub 2} (compound II). The morphology of synthesized CuNPs was characterized by transmission electron microscopy (TEM). The nano-particles were in the range of 13–37 nm with the average size of 23 nm. These materials were used to modify carbon paste electrode. Different electrochemical techniques, including cyclic voltammetry, electrochemical impedance spectroscopy and hydrodynamic chronoamperometry, were used to study the sensor behavior. These electrochemical sensors were used as a model for non-enzymatic detection of hydrogen peroxide (H{sub 2}O{sub 2}). To evaluate the abilities of the modified electrodes for H{sub 2}O{sub 2} detection, the electrochemical signals were compared in the absence and presence of H{sub 2}O{sub 2}. From them, two modified electrodes showed significant responses vs. H{sub 2}O{sub 2} addition. The amperograms illustrated that the sensors were selective for H{sub 2}O{sub 2} sensing with linear ranges of 5.14–1250 μmol L{sup −1} and 1.14–1120 μmol L{sup −1} with detection limits of 0.85 and 0.27 μmol L{sup −1} H{sub 2}O{sub 2}, sensitivities of 3545 and 11,293 μA mmol{sup −1} L and with response times less than 5 s for I/CPE and II/CPE, respectively. As further verification of the selected sensor, H{sub 2}O{sub 2} contained in milk sample was analyzed and the obtained results were comparable with the ones from classical control titration method. - Highlights: • Copper nanoparticles decorating on two new anchored type ligands were prepared. • Ligands are bonding to silica support as SiO{sub 2}–pro–NH{sub 2} and SiO{sub 2}–pro–NH–cyanuric–NH{sub 2}. • These materials were used as electrochemical sensors for H

Development of paper-based electrochemical sensors for water quality monitoring

Science.gov (United States)

Smith, Suzanne; Bezuidenhout, Petroné; Mbanjwa, Mesuli; Zheng, Haitao; Conning, Mariette; Palaniyandy, Nithyadharseni; Ozoemena, Kenneth; Land, Kevin

2016-02-01

We present a method for the development of paper-based electrochemical sensors for detection of heavy metals in water samples. Contaminated water leads to serious health problems and environmental issues. Paper is ideally suited for point-of-care testing, as it is low cost, disposable, and multi-functional. Initial sensor designs were manufactured on paper substrates using combinations of inkjet printing and screen printing technologies using silver and carbon inks. Bismuth onion-like carbon nanoparticle ink was manufactured and used as the active material of the sensor for both commercial and paper-based sensors, which were compared using standard electrochemical analysis techniques. The results highlight the potential of paper-based sensors to be used effectively for rapid water quality monitoring at the point-of-need.

Light-Regulated Electrochemical Sensor Array for Efficiently Discriminating Hazardous Gases.

Science.gov (United States)

Liang, Hongqiu; Zhang, Xin; Sun, Huihui; Jin, Han; Zhang, Xiaowei; Jin, Qinghui; Zou, Jie; Haick, Hossam; Jian, Jiawen

2017-10-27

Inadequate detection limit and unsatisfactory discrimination features remain the challenging issues for the widely applied electrochemical gas sensors. Quite recently, we confirmed that light-regulated electrochemical reaction significantly enhanced the electrocatalytic activity, and thereby can potentially extend the detection limit to the parts per billion (ppb) level. Nevertheless, impact of the light-regulated electrochemical reaction on response selectivity has been discussed less. Herein, we systematically report on the effect of illumination on discrimination features via design and fabrication of a light-regulated electrochemical sensor array. Upon illumination (light on), response signal to the examined gases (C 3 H 6 , NO, and CO) is selectively enhanced, resulting in the sensor array demonstrating disparate response patterns when compared with that of the sensor array operated at light off. Through processing all the response patterns derived from both light on and light off with a pattern recognition algorithm, a satisfactory discrimination feature is observed. In contrast, apparent mutual interference between NO and CO is found when the sensor array is solely operated without illumination. The impact mechanism of the illumination is studied and it is deduced that the effect of the illumination on the discriminating features can be mainly attributed to the competition of electrocatalytic activity and gas-phase reactivity. If the enhanced electrocatalytic activity (to specific gas) dominates the whole sensing progress, enhancements in the corresponding response signal would be observed upon illumination. Otherwise, illumination gives a negligible impact. Hence, the response signal to part of the examined gases is selectively enhanced by illumination. Conclusively, light-regulated electrochemical reaction would provide an efficient approach to designing future smart sensing devices.

Recent trends in carbon nanomaterial-based electrochemical sensors for biomolecules: A review

International Nuclear Information System (INIS)

Yang, Cheng; Denno, Madelaine E.; Pyakurel, Poojan; Venton, B. Jill

2015-01-01

Carbon nanomaterials are advantageous for electrochemical sensors because they increase the electroactive surface area, enhance electron transfer, and promote adsorption of molecules. Carbon nanotubes (CNTs) have been incorporated into electrochemical sensors for biomolecules and strategies have included the traditional dip coating and drop casting methods, direct growth of CNTs on electrodes and the use of CNT fibers and yarns made exclusively of CNTs. Recent research has also focused on utilizing many new types of carbon nanomaterials beyond CNTs. Forms of graphene are now increasingly popular for sensors including reduced graphene oxide, carbon nanohorns, graphene nanofoams, graphene nanorods, and graphene nanoflowers. In this review, we compare different carbon nanomaterial strategies for creating electrochemical sensors for biomolecules. Analytes covered include neurotransmitters and neurochemicals, such as dopamine, ascorbic acid, and serotonin; hydrogen peroxide; proteins, such as biomarkers; and DNA. The review also addresses enzyme-based electrodes that are used to detect non-electroactive species such as glucose, alcohols, and proteins. Finally, we analyze some of the future directions for the field, pointing out gaps in fundamental understanding of electron transfer to carbon nanomaterials and the need for more practical implementation of sensors. - Highlights: • We review the types of carbon nanomaterials used in electrochemical sensors. • Different materials and sensor designs are compared for classes of biomolecules. • Future challenges of better sensor design and implementation are assessed

Recent trends in carbon nanomaterial-based electrochemical sensors for biomolecules: A review

Energy Technology Data Exchange (ETDEWEB)

Yang, Cheng; Denno, Madelaine E.; Pyakurel, Poojan; Venton, B. Jill, E-mail: jventon@virginia.edu

2015-08-05

Carbon nanomaterials are advantageous for electrochemical sensors because they increase the electroactive surface area, enhance electron transfer, and promote adsorption of molecules. Carbon nanotubes (CNTs) have been incorporated into electrochemical sensors for biomolecules and strategies have included the traditional dip coating and drop casting methods, direct growth of CNTs on electrodes and the use of CNT fibers and yarns made exclusively of CNTs. Recent research has also focused on utilizing many new types of carbon nanomaterials beyond CNTs. Forms of graphene are now increasingly popular for sensors including reduced graphene oxide, carbon nanohorns, graphene nanofoams, graphene nanorods, and graphene nanoflowers. In this review, we compare different carbon nanomaterial strategies for creating electrochemical sensors for biomolecules. Analytes covered include neurotransmitters and neurochemicals, such as dopamine, ascorbic acid, and serotonin; hydrogen peroxide; proteins, such as biomarkers; and DNA. The review also addresses enzyme-based electrodes that are used to detect non-electroactive species such as glucose, alcohols, and proteins. Finally, we analyze some of the future directions for the field, pointing out gaps in fundamental understanding of electron transfer to carbon nanomaterials and the need for more practical implementation of sensors. - Highlights: • We review the types of carbon nanomaterials used in electrochemical sensors. • Different materials and sensor designs are compared for classes of biomolecules. • Future challenges of better sensor design and implementation are assessed.

A PVC/polypyrrole sensor designed for beef taste detection using electrochemical methods and sensory evaluation.

Science.gov (United States)

Zhu, Lingtao; Wang, Xiaodan; Han, Yunxiu; Cai, Yingming; Jin, Jiahui; Wang, Hongmei; Xu, Liping; Wu, Ruijia

2018-03-01

An electrochemical sensor for detection of beef taste was designed in this study. This sensor was based on the structure of polyvinyl chloride/polypyrrole (PVC/PPy), which was polymerized onto the surface of a platinum (Pt) electrode to form a Pt-PPy-PVC film. Detecting by electrochemical methods, the sensor was well characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The sensor was applied to detect 10 rib-eye beef samples and the accuracy of the new sensor was validated by sensory evaluation and ion sensor detection. Several cluster analysis methods were used in the study to distinguish the beef samples. According to the obtained results, the designed sensor showed a high degree of association of electrochemical detection and sensory evaluation, which proved a fast and precise sensor for beef taste detection. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Facile Electrochemical Sensor for Nonylphenol Determination Based on the Enhancement Effect of Cetyltrimethylammonium Bromide

Directory of Open Access Journals (Sweden)

Qing Lu

2013-01-01

Full Text Available A facile electrochemical sensor for the determination of nonylphenol (NP was fabricated in this work. Cetyltrimethylammonium bromide (CTAB, which formed a bilayer on the surface of the carbon paste (CP electrode, displayed a remarkable enhancement effect for the electrochemical oxidation of NP. Moreover, the oxidation peak current of NP at the CTAB/CP electrode demonstrated a linear relationship with NP concentration, which could be applied in the direct determination of NP. Some experimental parameters were investigated, such as external solution pH, mode and time of accumulation, concentration and modification time of CTAB and so on. Under optimized conditions, a wide linear range from 1.0 × 10−7 mol·L−1 to 2.5 × 10−5 mol·L−1 was obtained for the sensor, with a low limit of detection at 1.0 × 10−8 mol·L−1. Several distinguishing advantages of the as-prepared sensor, including facile fabrication, easy operation, low cost and so on, suggest a great potential for its practical applications.

Membrane-Coated Electrochemical Sensor for Corrosion Monitoring in Natural Gas Pipelines

Directory of Open Access Journals (Sweden)

J. Beck

2017-07-01

Full Text Available Electrochemical sensors can be used for a wide range of online in- situ process monitoring applications. However, the lack of a consistent electrolyte layer has previously limited electrochemical monitoring in gas and supercritical fluid streams. A solid state sensor is being designed that uses an ion conducting membrane to perform conductivity and corrosion measurements in natural gas pipelines up to 1000 psi. Initial results show that membrane conductivity measurements can be correlated directly to water content down to dew points of 1°C with good linearity. Corrosion monitoring can also be performed using methods such as linear polarization resistance and electrochemical impedance spectroscopy (EIS, though care must be taken in the electrode design to minimize deviation between sensors.

A Printed Organic Amplification System for Wearable Potentiometric Electrochemical Sensors.

Science.gov (United States)

Shiwaku, Rei; Matsui, Hiroyuki; Nagamine, Kuniaki; Uematsu, Mayu; Mano, Taisei; Maruyama, Yuki; Nomura, Ayako; Tsuchiya, Kazuhiko; Hayasaka, Kazuma; Takeda, Yasunori; Fukuda, Takashi; Kumaki, Daisuke; Tokito, Shizuo

2018-03-02

Electrochemical sensor systems with integrated amplifier circuits play an important role in measuring physiological signals via in situ human perspiration analysis. Signal processing circuitry based on organic thin-film transistors (OTFTs) have significant potential in realizing wearable sensor devices due to their superior mechanical flexibility and biocompatibility. Here, we demonstrate a novel potentiometric electrochemical sensing system comprised of a potassium ion (K + ) sensor and amplifier circuits employing OTFT-based pseudo-CMOS inverters, which have a highly controllable switching voltage and closed-loop gain. The ion concentration sensitivity of the fabricated K + sensor was 34 mV/dec, which was amplified to 160 mV/dec (by a factor of 4.6) with high linearity. The developed system is expected to help further the realization of ultra-thin and flexible wearable sensor devices for healthcare applications.

Chip cleaning and regeneration for electrochemical sensor arrays

Energy Technology Data Exchange (ETDEWEB)

Bhalla, Vijayender [Biochemistry Department ' G.Moruzzi' , University of Bologna, Via Irnerio 48, 40126 Bologna (Italy); Carrara, Sandro, E-mail: sandro.carrara@epfl.c [Biochemistry Department ' G.Moruzzi' , University of Bologna, Via Irnerio 48, 40126 Bologna (Italy); Stagni, Claudio [Department DEIS, University of Bologna, viale Risorgimento 2, 40136 Bologna (Italy); Samori, Bruno [Biochemistry Department ' G.Moruzzi' , University of Bologna, Via Irnerio 48, 40126 Bologna (Italy)

2010-04-02

Sensing systems based on electrochemical detection have generated great interest because electronic readout may replace conventional optical readout in microarray. Moreover, they offer the possibility to avoid labelling for target molecules. A typical electrochemical array consists of many sensing sites. An ideal micro-fabricated sensor-chip should have the same measured values for all the equivalent sensing sites (or spots). To achieve high reliability in electrochemical measurements, high quality in functionalization of the electrodes surface is essential. Molecular probes are often immobilized by using alkanethiols onto gold electrodes. Applying effective cleaning methods on the chip is a fundamental requirement for the formation of densely-packed and stable self-assembly monolayers. However, the available well-known techniques for chip cleaning may not be so reliable. Furthermore, it could be necessary to recycle the chip for reuse. Also in this case, an effective recycling technique is required to re-obtain well cleaned sensing surfaces on the chip. This paper presents experimental results on the efficacy and efficiency of the available techniques for initial cleaning and further recycling of micro-fabricated chips. Piranha, plasma, reductive and oxidative cleaning methods were applied and the obtained results were critically compared. Some interesting results were attained by using commonly considered cleaning methodologies. This study outlines oxidative electrochemical cleaning and recycling as the more efficient cleaning procedure for electrochemical based sensor arrays.

Electrochemical sensors based on gold nanoparticles modified with rhodamine B hydrazide to sensitively detect Cu(II)

Energy Technology Data Exchange (ETDEWEB)

Peng, Donglai; Hu, Bin; Kang, Mengmeng [Henan Provincial Key Laboratory of Surface and Interface Science, Zhengzhou University of Light Industry, No. 136, Science Avenue, Zhengzhou 450001 (China); Wang, Minghua [Henan Collaborative Innovation Center of Environmental Pollution Control and Ecological Restoration, Zhengzhou University of Light Industry, No.136, Science Avenue, Zhengzhou 450001 (China); He, Linghao [Henan Provincial Key Laboratory of Surface and Interface Science, Zhengzhou University of Light Industry, No. 136, Science Avenue, Zhengzhou 450001 (China); Zhang, Zhihong, E-mail: mainzhh@163.com [Henan Provincial Key Laboratory of Surface and Interface Science, Zhengzhou University of Light Industry, No. 136, Science Avenue, Zhengzhou 450001 (China); Henan Collaborative Innovation Center of Environmental Pollution Control and Ecological Restoration, Zhengzhou University of Light Industry, No.136, Science Avenue, Zhengzhou 450001 (China); Fang, Shaoming, E-mail: mingfang@zzuli.edu.cn [Henan Provincial Key Laboratory of Surface and Interface Science, Zhengzhou University of Light Industry, No. 136, Science Avenue, Zhengzhou 450001 (China); Henan Collaborative Innovation Center of Environmental Pollution Control and Ecological Restoration, Zhengzhou University of Light Industry, No.136, Science Avenue, Zhengzhou 450001 (China)

2016-12-30

Highlights: • An electrochemical sensor based on gold nanoparticles modified with rhodamine B hydrazide (AuNPs-RBH) was developed. • The sensor was applied in the highly sensitive and selective detection of Cu{sup 2+} in water. • The electrochemical sensor displays excellent regeneration, stability, and practicability for Cu{sup 2+} detection. • EIS was used to determine Cu{sup 2+} ions in an aqueous solution with the developed AuNPs-RBH-based electrochemical sensor. - Abstract: An electrochemical sensor based on gold nanoparticles (Au NPs) modified with rhodamine B hydrazide (RBH) (AuNPs-RBH) was developed and applied in the highly sensitive and selective detection of Cu{sup 2+} in water. RBH molecules were bounded onto the surface of AuNPs via the strong interaction between the amino groups and Au NPs. The chemical structure variations were characterized by X-ray photoelectron spectroscopy and fluoresence spectroscopy. Additionally, electrochemical impedance spectroscopy was used to determine Cu{sup 2+} ions in an aqueous solution with the developed AuNPs-RBH-based electrochemical sensor. Results show that the fabricated sensor exhibits good electrochemical performance because of the presence of Au NPs and high affinity with the Cu{sup 2+} resulting from the strong coordination chemistry between Cu{sup 2+} and RBH. The as-developed sensor towards detecting Cu{sup 2+} has a detection limitation of 12.5 fM within the concentration range of 0.1 pM–1 nM by using the electrochemical impedance technique. It also displays excellent selectivity, regeneration, stability, and practicability for Cu{sup 2+} detection. Therefore, the new strategy of the RBH-based electrochemical sensor exhibits great potential application in environment treatment and protection.

Novel Ag@TiO2 nanocomposite synthesized by electrochemically active biofilm for nonenzymatic hydrogen peroxide sensor

International Nuclear Information System (INIS)

Khan, Mohammad Mansoob; Ansari, Sajid Ali; Lee, Jintae; Cho, Moo Hwan

2013-01-01

A novel nonenzymatic sensor for H 2 O 2 was developed based on an Ag@TiO 2 nanocomposite synthesized using a simple and cost effective approach with an electrochemically active biofilm. The optical, structural, morphological and electrochemical properties of the as-prepared Ag@TiO 2 nanocomposite were examined by UV–vis spectroscopy, X-ray diffraction, transmission electron microscopy and cyclic voltammetry (CV). The Ag@TiO 2 nanocomposite was fabricated on a glassy carbon electrode (GCE) and their electrochemical performance was analyzed by CV, differential pulse voltammetry and electrochemical impedance spectroscopy. The Ag@TiO 2 nanocomposite modified GCE (Ag@TiO 2 /GCE) displayed excellent performance towards H 2 O 2 sensing at − 0.73 V in the linear response range from 0.83 μM to 43.3 μM, within a detection limit and sensitivity of 0.83 μM and ∼ 65.2328 ± 0.01 μAμM −1 cm −2 , respectively. In addition, Ag@TiO 2 /GCE exhibited good operational reproducibility and long term stability. - Graphical abstract: Synthesis of Ag@TiO 2 nanocomposite by electrochemically active biofilm for H 2 O 2 sensing. - Highlights: • Electrochemically active biofilm (EAB) • EAB mediated synthesis of Ag@TiO 2 nanocomposite • Ag@TiO 2 nanocomposite modified glassy carbon electrode • Ag@TiO 2 /GCE for H 2 O 2 sensing • Nonenzymatic sensor for H 2 O 2

Highly selective and sensitive sensor based on an organic electrochemical transistor for the detection of ascorbic acid.

Science.gov (United States)

Zhang, Lijun; Wang, Guiheng; Wu, Di; Xiong, Can; Zheng, Lei; Ding, Yunsheng; Lu, Hongbo; Zhang, Guobing; Qiu, Longzhen

2018-02-15

In this study, an organic electrochemical transistor sensor (OECT) with a molecularly imprinted polymer (MIP)-modified gate electrode was prepared for the detection of ascorbic acid (AA). The combination of the amplification function of an OECT and the selective specificity of MIPs afforded a highly sensitive, selective OECT sensor. Cyclic voltammetry and electrochemical impedance spectroscopy measurements were carried out to monitor the stepwise fabrication of the modified electrodes and the adsorption capacity of the MIP/Au electrodes. Atomic force microscopy was employed for examining the surface morphology of the electrodes. Important detection parameters, pH and detection temperature were optimized. With the change in the relative concentration of AA from 1μM to 100μM, the MIP-OECT sensor exhibited a low detection limit of 10nM (S/N > 3) and a sensitivity of 75.3μA channel current change per decade under optimal conditions. In addition, the MIP-OECT sensor exhibited excellent specific recognition ability to AA, which prevented the interference from other structurally similar compounds (e.g., aspartic acid, glucose, uric acid, glycine, glutathione, H 2 O 2 ), and common metal ions (K + , Na + , Ca 2+ , Mg 2+ , and Fe 2+ ). In addition, a series of vitamin C beverages were analyzed to demonstrate the feasibility of the MIP-OECT sensor. Using the proposed principle, several other sensors with improved performance can be constructed via the modification of organic electrochemical transistors with appropriate MIP films. Copyright © 2017 Elsevier B.V. All rights reserved.

Aptamer based electrochemical sensors for emerging environmental pollutants

Directory of Open Access Journals (Sweden)

Akhtar eHAYAT

2014-06-01

Full Text Available Environmental contaminants monitoring is one of the key issues in understanding and managing hazards to human health and ecosystems. In this context, aptamer based electrochemical sensors have achieved intense significance because of their capability to resolve a potentially large number of problems and challenges in environmental contamination. An aptasensor is a compact analytical device incorporating an aptamer (oligonulceotide as the sensing element either integrated within or intimately associated with a physiochemical transducer surface. Nucleic acid is well known for the function of carrying and passing genetic information, however, it has found a key role in analytical monitoring during recent years. Aptamer based sensors represent a novelty in environmental analytical science and there are great expectations for their promising performance as alternative to conventional analytical tools. This review paper focuses on the recent advances in the development of aptamer based electrochemical sensors for environmental applications with special emphasis on emerging pollutants.

A Novel of Multi-wall Carbon Nanotubes/Chitosan Electrochemical Sensor for Determination of Cupric ion

Science.gov (United States)

Tan, Funeng; Li, Lei

2018-03-01

A multi-wall carbon nanotubes/Chitosan electrochemical sensor had been fabricated by dropping CHS/MWNT solution directly onto the GC surface. The sensor was charactered by cyclic voltammetry and AC impedance with K3Fe(CN)6 as a electrochemical probe; Cyclic voltammograms(CV) and electrochemical impedance spectroscopy(EIS) indicated that the active area and electrochemical behavior of the sensor increased and improved significantly after the electrode was modified by carbon nanotubes dispersed by the chitosan. The sensor showed good electrocatalytic activity of K3Fe(CN)6. Also, from the cyclic voltammograms, we can see the process was diffusion controlled on the bare electrode and kinetics and diffusion controlled on the modified electrode. Finally Cu2+ responsed sensitively at the sensor which supplied a new method for the detection of Cu2+.

Pyrrole-phenylboronic acid: a novel monomer for dopamine recognition and detection based on imprinted electrochemical sensor.

Science.gov (United States)

Zhong, Min; Teng, Ying; Pang, Shufen; Yan, Liqin; Kan, Xianwen

2015-02-15

A molecular imprinting polymer (MIP) based electrochemical sensor was successfully prepared for dopamine (DA) recognition and detection using pyrrole-phenylboronic acid (py-PBA) as a novel electropolymerized monomer. py-PBA could form cyclic boronic ester bond with DA, thus endowing a double recognition capacity of the sensor to DA in the combination of the imprinted effect of MIP. Compared with the sensor prepared using pyrrole or phenylboronic acid as electropolymerized monomer, the present sensor exhibited a remarkable high imprinted factor to DA. The influence factors including pH value, the mole ratio between monomer and template molecule, electropolymerization scan rate, and scan cycles of electropolymerization process were investigated and optimized. Under the optimal conditions, the sensor could recognize DA from its analogs and monosaccharides. A linear ranging from 5.0 × 10(-8) to 1.0 × 10(-5) mol/L for the detection of DA was obtained with a detection limit of 3.3 × 10(-8) mol/L (S/N = 3). The sensor has been applied to analyze DA in injection samples with satisfactory results. Copyright © 2014 Elsevier B.V. All rights reserved.

Electrochemical sensors for biofilm and biocorrosion

Energy Technology Data Exchange (ETDEWEB)

Tribollet, B. [UPR 15 du CNRS, Universite Paris 6, 4 Place Jussieu, 75252 Paris Cedex05 (France)

2003-07-01

The presence of biofilm modifies the electrochemical properties of the interface and the mass transport near the interface. Two biofilm effects are damageable: the reduction of heat and/or mass transfer and the biocorrosion or microbiologically influenced corrosion (MIC). Two kinds of electrochemical sensors were developed: the first kind for the biofilm detection and the second one to evaluate the MIC risk. The biofilm detection is obtained by considering either the potential modification of the interface or the mass transport modification. The mass transport modification is analysed by considering the limiting diffusion current measured on a gold electrode where the biofilm development occurs. The MIC risk is evaluated with a sensor composed of two concentric electrodes in the material under investigation (e.g. carbon steel): a small disk electrode in the centre and a large ring. In a first step, a pit is artificially initiated by applying a current through these electrodes. In a second step, the risk factors of MIC are investigated by analysing the free coupling current circulating between these two short-circuited electrodes. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Electrochemical surface plasmon resonance sensor based on two-electrode configuration

International Nuclear Information System (INIS)

Zhang, Bing; Dong, Wei; Wen, Yizhang; Pang, Kai; Wang, Xiaoping; Li, Yazhuo; Zhan, Shuyue

2016-01-01

To obtain detailed information about electrochemistry reactions, a two-electrode electrochemical surface plasmon resonance (EC-SPR) sensor has been proposed. We describe the theory of potential modulation for this novel sensor and determine the factors that can change the SPR resonance angle. The reference electrode in three-electrode configuration was eliminated, and comparing with several other electrode materials, activated carbon (AC) is employed as the suitable counter electrode for its potential stability. Just like three-electrode configuration, the simpler AC two-electrode system can also obtain detailed information about the electrochemical reactions. (paper)

Ionic Liquid-Based Optical and Electrochemical Carbon Dioxide Sensors

Science.gov (United States)

Behera, Kamalakanta; Pandey, Shubha; Kadyan, Anu; Pandey, Siddharth

2015-01-01

Due to their unusual physicochemical properties (e.g., high thermal stability, low volatility, high intrinsic conductivity, wide electrochemical windows and good solvating ability), ionic liquids have shown immense application potential in many research areas. Applications of ionic liquid in developing various sensors, especially for the sensing of biomolecules, such as nucleic acids, proteins and enzymes, gas sensing and sensing of various important ions, among other chemosensing platforms, are currently being explored by researchers worldwide. The use of ionic liquids for the detection of carbon dioxide (CO2) gas is currently a major topic of research due to the associated importance of this gas with daily human life. This review focuses on the application of ionic liquids in optical and electrochemical CO2 sensors. The design, mechanism, sensitivity and detection limit of each type of sensor are highlighted in this review. PMID:26690155

Ionic Liquid-Based Optical and Electrochemical Carbon Dioxide Sensors.

Science.gov (United States)

Behera, Kamalakanta; Pandey, Shubha; Kadyan, Anu; Pandey, Siddharth

2015-12-04

Due to their unusual physicochemical properties (e.g., high thermal stability, low volatility, high intrinsic conductivity, wide electrochemical windows and good solvating ability), ionic liquids have shown immense application potential in many research areas. Applications of ionic liquid in developing various sensors, especially for the sensing of biomolecules, such as nucleic acids, proteins and enzymes, gas sensing and sensing of various important ions, among other chemosensing platforms, are currently being explored by researchers worldwide. The use of ionic liquids for the detection of carbon dioxide (CO₂) gas is currently a major topic of research due to the associated importance of this gas with daily human life. This review focuses on the application of ionic liquids in optical and electrochemical CO₂ sensors. The design, mechanism, sensitivity and detection limit of each type of sensor are highlighted in this review.

Ionic Liquid-Based Optical and Electrochemical Carbon Dioxide Sensors

Directory of Open Access Journals (Sweden)

Kamalakanta Behera

2015-12-01

Full Text Available Due to their unusual physicochemical properties (e.g., high thermal stability, low volatility, high intrinsic conductivity, wide electrochemical windows and good solvating ability, ionic liquids have shown immense application potential in many research areas. Applications of ionic liquid in developing various sensors, especially for the sensing of biomolecules, such as nucleic acids, proteins and enzymes, gas sensing and sensing of various important ions, among other chemosensing platforms, are currently being explored by researchers worldwide. The use of ionic liquids for the detection of carbon dioxide (CO2 gas is currently a major topic of research due to the associated importance of this gas with daily human life. This review focuses on the application of ionic liquids in optical and electrochemical CO2 sensors. The design, mechanism, sensitivity and detection limit of each type of sensor are highlighted in this review.

Electrochemical impedimetric sensor based on molecularly imprinted polymers/sol-gel chemistry for methidathion organophosphorous insecticide recognition.

Science.gov (United States)

Bakas, Idriss; Hayat, Akhtar; Piletsky, Sergey; Piletska, Elena; Chehimi, Mohamed M; Noguer, Thierry; Rouillon, Régis

2014-12-01

We report here a novel method to detect methidathion organophosphorous insecticides. The sensing platform was architected by the combination of molecularly imprinted polymers and sol-gel technique on inexpensive, portable and disposable screen printed carbon electrodes. Electrochemical impedimetric detection technique was employed to perform the label free detection of the target analyte on the designed MIP/sol-gel integrated platform. The selection of the target specific monomer by electrochemical impedimetric methods was consistent with the results obtained by the computational modelling method. The prepared electrochemical MIP/sol-gel based sensor exhibited a high recognition capability toward methidathion, as well as a broad linear range and a low detection limit under the optimized conditions. Satisfactory results were also obtained for the methidathion determination in waste water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

The strategies of DNA immobilization and hybridization detection mechanism in the construction of electrochemical DNA sensor: A review

Directory of Open Access Journals (Sweden)

Jahwarhar Izuan Abdul Rashid

2017-11-01

Full Text Available In recent years, electrochemical deoxyribonucleic acid (DNA sensor has recently emerged as promising alternative clinical diagnostic devices especially for infectious disease by exploiting DNA recognition events and converting them into an electrochemical signal. This is because the existing DNA diagnostic method possesses certain drawbacks such as time-consuming, expensive, laborious, low selectivity and sensitivity. DNA immobilization strategies and mechanism of electrochemical detection are two the most important aspects that should be considered before developing highly selective and sensitive electrochemical DNA sensor. Here, we focus on some recent strategies for DNA probes immobilization on the surface of electrochemical transducer such as adsorption, covalent bonding and Avidin/Streptavidin-Biotin interaction on the electrode surface for specific interaction with its complementary DNA target. A numerous approach for DNA hybridization detection based electrochemical technique that frequently used including direct DNA electrochemical detection and label based electrochemical (redox-active indicator, enzyme label and nanoparticles were also discussed in aiming to provide general guide for the design of electrochemical DNA sensor. We also discussed the challenges and suggestions to improve the application of electrochemical DNA sensor at point-care setting. Keywords: Electrochemical DNA sensor, DNA immobilization, DNA hybridization, Electrochemical mechanism

Embroidered electrochemical sensors on gauze for rapid quantification of wound biomarkers.

Science.gov (United States)

Liu, Xiyuan; Lillehoj, Peter B

2017-12-15

Electrochemical sensors are an attractive platform for analytical measurements due to their high sensitivity, portability and fast response time. These attributes also make electrochemical sensors well suited for wearable applications which require excellent flexibility and durability. Towards this end, we have developed a robust electrochemical sensor on gauze via a unique embroidery fabrication process for quantitative measurements of wound biomarkers. For proof of principle, this biosensor was used to detect uric acid, a biomarker for wound severity and healing, in simulated wound fluid which exhibits high specificity, good linearly from 0 to 800µM, and excellent reproducibility. Continuous sensing of uric acid was also performed using this biosensor which reveals that it can generate consistent and accurate measurements for up to 7h. Experiments to evaluate the robustness of the embroidered gauze sensor demonstrate that it offers excellent resilience against mechanical stress and deformation, making it a promising wearable platform for assessing and monitoring wound status in situ. Copyright © 2017 Elsevier B.V. All rights reserved.

Online Monitoring of Electrochemical Degradation of Paracetamol through a Biomimetic Sensor

OpenAIRE

Mariana Calora Quintino de Oliveira; Marcos Roberto de Vasconcelos Lanza; José Luis Paz Jara; Maria Del Pilar Taboada Sotomayor

2011-01-01

This paper reports, for the first time, the online monitoring to the electrochemical degradation of the paracetamol using a biomimetic sensor coupled to a Flow Injection Analysis (FIA) system. The electrochemical degradation of the drug was carried out in aqueous medium using a flow-by reactor with a DSA anode. The process efficiency was monitored at real time by the biomimetic sensor constructed by modifying a glassy carbon electrode with a Nafion membrane doped with iron tetrapyridinoporphy...

Preparation and characterization of green-nano-composite material based on polyaniline, multiwalled carbon nano tubes and carboxymethyl cellulose: For electrochemical sensor applications.

Science.gov (United States)

Gautam, Vineeta; Singh, Karan Pratap; Yadav, Vijay Laxmi

2018-06-01

In this paper, we are presenting the preparation and characterization of "polyaniline/multiwalled carbon nanotubes/carboxymethyl cellulose" based novel composite material. It's morphological, thermal, structural, and electrochemical properties were investigated by using different instrumental techniques. During the in-situ chemical polymerization of aniline in the aqueous suspension of CMC and MWCNTs, the particle size change in two different ways "top to bottom" (low molecular weight oligomers grows in size) and "bottom to top" (long fibers of CMC fragmented in the reaction mixture). The combination of these two processes facilitated the fabrication of an integrated green-nano-composite material. In addition, a little amount of conductive nanofillers (MWCNTs) boosts the electrical and electrocatalytic properties of the material. Electron-rich centers of benzenoid rings exhibited π-π stacking with sp 2 carbon of MWCNTs. CMC dominantly impact on the properties of PANI, negatively charged carboxylate group of CMC ionically bonded with protonated amine/imine. FTIR and Raman analysis confirmed that the material has dominated quinoid units and effective charge transfer. Hydroxyl and carboxyl groups and bonded water molecules of CMC results in a network of hydrogen bonds (which induced directional property). PANI/MWCNTs/CMC have nanobead-like structures (TEM analysis), large surface area, large pore volume, small pore diameter (BET and BJH studies) and good dispersion ability in the aqueous phase. Nanostructures of aligned PANI exhibited excellent electrochemical properties have attracted increasing attention. Modified carbon paste electrode was used for electrocatalytic detection of ascorbic acid (as a model analyte). The sensor exhibited a linear range 0.05 mM-5 mM, sensitivity 100.63 μA mM -1  cm -2 , and limit of detection 0.01 mM. PANI/MWCNTs/CMC is suitable nanocomposite material for apply electroactive/conducting ink and membrane (which could be

Development of an electrochemical ascorbic acid sensor based on the incorporation of a ferricyanide mediator with a polyelectrolyte-calcium carbonate microsphere

International Nuclear Information System (INIS)

Li Feng; Tang Chenfei; Liu Shufeng; Ma Guangran

2010-01-01

A novel electro-active material was successfully prepared with Fe(CN) 6 3- ions loaded by electrostatic interaction onto the layer of poly(allylamine) hydrochloride (PAH), which was first assembled on prepared poly(sodium 4-styrenesulfonate) (PSS)-doped porous calcium carbonate (CaCO 3 ) microspheres. Further, an electrochemical sensor for use in ascorbic acid (AA) detection was constructed with the use of the above electro-active materials embedded into a chitosan (CS) sol-gel matrix as an electron mediator. The electrocatalytic oxidation of AA by ferricyanide was observed at the potential of 0.27 V, which was negative-shifted compared with that by direct electrochemical oxidation of AA on a glassy carbon electrode. The experimental parameters, including the pH value of testing solution and the applied potential for detection of AA, were optimized. The current electrochemical sensor not only exhibited a good reproducibility and storage stability, but also showed a fast amperometric response to AA in a linear range (1.0 x 10 -6 to 2.143 x 10 -3 M), a low detection limit (7.0 x 10 -7 M), a fast response time ( -1 ).

Polypyrrole Composite Film for Highly Sensitive and Selective Electrochemical Determination Sensors

International Nuclear Information System (INIS)

Zheng, Xiangli; Tian, Dong; Duan, Shuo; Wei, Maochao; Liu, Shan; Zhou, Changli; Li, Qing; Wu, Gang

2014-01-01

In this paper, polypyrrole (PPy) and benz[a]anthracene-7,12-dione (BaD) were electro-polymerized onto a pyrolytic graphite electrode (PGE), constructing a novel BaD/PPy/PGE platform for electrochemical sensoring. The morphology and electrochemical properties of the fabricated BaD/PPy/PGE were characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Furthermore, the electrochemical behavior of benzo[k]fluoranthene (BkF) at the BaD/PPy/PGE was investigated. Due to the specific interactions between BkF and BaD, a wide linear range of BkF detection from 1.0 × 10 −12 to 1.0 × 10 −9 M with good linearity (R 2 = 0.9962) and a low detection limit (1.0 × 10 −13 M, S/N = 3) were demonstrated. Importantly, other similar aromatics which had one ring or more than two rings, such as benzo[a]anthracene, benzo[a]pyrene, pyrene, benzo[ghi]peryle, anthracene, phenanthrene, naphthalene and parachlorophenol, showed insignificant interference on BkF detection. Consequently, this novel BaD/PPy/PGE with excellent stability and selectivity holds promise as an effective BkF electrochemical sensor in aqueous solution. As an example for its practical application, the newly developed sensor was applied to quantitative determination of BkF in waste water samples obtained from a coking plant with satisfactory sensitivity, selectivity, and reversibility

An electrochemical sensor for monitoring oxygen or hydrogen in water

International Nuclear Information System (INIS)

Leitai Yang; Morris, D.R.; Lister, D.H.

1997-01-01

Preliminary studies have been done on a simple electrochemical sensor which shows promise as a cheap, robust instrument for measuring dissolved oxygen or hydrogen in water. The sensor is based upon the solid-state electrolyte ''Nafion'' (trade name of perfluorinated sulphonic acid, manufactured by DuPont Inc.). The Nafion was dissolved in a mixture of aliphatic alcohols, made into a slurry with platinum black, and applied to a ∼1 cm-square electrode made of stainless steel gauze. The potential of the electrode was measured relative to a standard calomel electrode (SCE) in acid solutions at room temperature through which mixtures of oxygen and nitrogen or hydrogen and nitrogen were bubbled. The sensor was responsive to the equilibrating gas with good reproducibility. A similar sensor without the Nafion was not at all sensitive to changes in oxygen concentration. The voltage response of the sensor showed non-Nernstian behaviour, which suggests that the electrochemical reactions at the electrode surface are complex. Further testing of the sensor is required to verify its sensitivity and responsiveness in typical reactor coolant chemistries and to demonstrate its durability over a range of temperatures. (author). 4 refs, 4 figs, 1 tab

An electrochemical sensor for monitoring oxygen or hydrogen in water

Energy Technology Data Exchange (ETDEWEB)

Yang, Leitai; Morris, D R; Lister, D H [University of New Brunswick, Fredericton (Canada). Dept. of Chemical Engineering

1997-02-01

Preliminary studies have been done on a simple electrochemical sensor which shows promise as a cheap, robust instrument for measuring dissolved oxygen or hydrogen in water. The sensor is based upon the solid-state electrolyte ``Nafion`` (trade name of perfluorinated sulphonic acid, manufactured by DuPont Inc.). The Nafion was dissolved in a mixture of aliphatic alcohols, made into a slurry with platinum black, and applied to a {approx}1 cm-square electrode made of stainless steel gauze. The potential of the electrode was measured relative to a standard calomel electrode (SCE) in acid solutions at room temperature through which mixtures of oxygen and nitrogen or hydrogen and nitrogen were bubbled. The sensor was responsive to the equilibrating gas with good reproducibility. A similar sensor without the Nafion was not at all sensitive to changes in oxygen concentration. The voltage response of the sensor showed non-Nernstian behaviour, which suggests that the electrochemical reactions at the electrode surface are complex. Further testing of the sensor is required to verify its sensitivity and responsiveness in typical reactor coolant chemistries and to demonstrate its durability over a range of temperatures. (author). 4 refs, 4 figs, 1 tab.

Facile preparation of a DNA sensor for rapid herpes virus detection

Energy Technology Data Exchange (ETDEWEB)

Tam, Phuong Dinh, E-mail: tampd-hast@mail.hut.edu.vn [Hanoi Advanced School of Science and Technology, Hanoi University of Technology (Viet Nam); Tuan, Mai Anh, E-mail: tuanma-itims@mail.hut.edu.vn [International Training Institute for Materials Science, Hanoi University of Technology (Viet Nam); Huy, Tran Quang [National Institute of Hygiene and Epidemiology (NIHE), 01 Yersin, Hai Ba Trung District, Hanoi (Viet Nam); Le, Anh-Tuan [Hanoi Advanced School of Science and Technology, Hanoi University of Technology (Viet Nam); Hieu, Nguyen Van, E-mail: hieu@itims.edu.vn [International Training Institute for Materials Science, Hanoi University of Technology (Viet Nam)

2010-10-12

In this paper, a simple DNA sensor platform was developed for rapid herpes virus detection in real samples. The deoxyribonucleic acid (DNA) sequences of the herpes simplex virus (DNA probe) were directly immobilized on the surface of interdigitated electrodes by electrochemical polymerization along with pyrrole monomers. The potential was scanned from - 0.7 to + 0.6 V, and the scanning rate was 100 mV/s. Fourier transform infrared spectroscopy was employed to verify specific DNA sequence binding and the conducting polymer. The morphology of the conducting polymer doped with DNA strands was characterized using a field emission scanning electron microscope. As-obtained DNA sensor was used to detect the herpes virus DNA in the real samples. The results show that the current DNA sensors detected the lowest DNA concentration of 2 nM. This sensitivity appears to be better than that of the DNA sensors prepared by immobilization of the DNA probe on the 3-aminopropyl-triethoxy-silance (APTS) membrane.

Facile preparation of a DNA sensor for rapid herpes virus detection

International Nuclear Information System (INIS)

Tam, Phuong Dinh; Tuan, Mai Anh; Huy, Tran Quang; Le, Anh-Tuan; Hieu, Nguyen Van

2010-01-01

In this paper, a simple DNA sensor platform was developed for rapid herpes virus detection in real samples. The deoxyribonucleic acid (DNA) sequences of the herpes simplex virus (DNA probe) were directly immobilized on the surface of interdigitated electrodes by electrochemical polymerization along with pyrrole monomers. The potential was scanned from - 0.7 to + 0.6 V, and the scanning rate was 100 mV/s. Fourier transform infrared spectroscopy was employed to verify specific DNA sequence binding and the conducting polymer. The morphology of the conducting polymer doped with DNA strands was characterized using a field emission scanning electron microscope. As-obtained DNA sensor was used to detect the herpes virus DNA in the real samples. The results show that the current DNA sensors detected the lowest DNA concentration of 2 nM. This sensitivity appears to be better than that of the DNA sensors prepared by immobilization of the DNA probe on the 3-aminopropyl-triethoxy-silance (APTS) membrane.

Recent trends in carbon nanomaterial-based electrochemical sensors for biomolecules: A review

Science.gov (United States)

Yang, Cheng; Denno, Madelaine E.; Pyakurel, Poojan; Venton, B. Jill

2015-01-01

Carbon nanomaterials are advantageous for electrochemical sensors because they increase the electroactive surface area, enhance electron transfer, and promote adsorption of molecules. Carbon nanotubes (CNTs) have been incorporated into electrochemical sensors for biomolecules and strategies have included the traditional dip coating and drop casting methods, direct growth of CNTs on electrodes and the use of CNT fibers and yarns made exclusively of CNTs. Recent research has also focused on utilizing many new types of carbon nanomaterials beyond CNTs. Forms of graphene are now increasingly popular for sensors including reduced graphene oxide, carbon nanohorns, graphene nanofoams, graphene nanorods, and graphene nanoflowers. In this review, we compare different carbon nanomaterial strategies for creating electrochemical sensors for biomolecules. Analytes covered include neurotransmitters and neurochemicals, such as dopamine, ascorbic acid, and serotonin; hydrogen peroxide; proteins, such as biomarkers; and DNA. The review also addresses enzyme-based electrodes that are used to detect non-electroactive species such as glucose, alcohols, and proteins. Finally, we analyze some of the future directions for the field, pointing out gaps in fundamental understanding of electron transfer to carbon nanomaterials and the need for more practical implementation of sensors. PMID:26320782

A sensitive electrochemical chlorophenols sensor based on nanocomposite of ZnSe quantum dots and cetyltrimethylammonium bromide

International Nuclear Information System (INIS)

Li, Jianjun; Li, Xiao; Yang, Ran; Qu, Lingbo; Harrington, Peter de B.

2013-01-01

Graphical abstract: A very sensitive and simple electrochemical sensor for chlorophenols (CPs) based on nanocomposite of cetyltrimethylammonium bromide (CTAB) and ZnSe quantum dots (ZnSe–CTAB) through electrostatic self-assembly technology was built for the first time. The nanocomposite of ZnSe–CTAB introduced a favorable access for the electron transfer and showed excellent electrocatalytic activity for the oxidation of CPs. -- Highlights: •Nanocomposite based ZnSe QDs and CTAB was prepared and characterized. •A novel electrochemical sensor for the determination of CPs was built. •The proposed sensor was more sensitive, simple and environment-friendly. -- Abstract: In this work, a very sensitive and simple electrochemical sensor for chlorophenols (CPs) based on a nanocomposite of cetyltrimethylammonium bromide (CTAB) and ZnSe quantum dots (ZnSe–CTAB) through electrostatic self-assembly technology was built for the first time. The composite of ZnSe–CTAB introduced a favorable access for the electron transfer and gave superior electrocatalytic activity for the oxidation of CPs than ZnSe QDs and CTAB alone. Differential pulse voltammetry (DPV) was used for the quantitative determination of the CPs including 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP) and pentachlorophenol (PCP). Under the optimum conditions, the peak currents of the CPs were proportional to their concentrations in the range from 0.02 to 10.0 μM for 2-CP, 0.006 to 9.0 μM for 2,4-DCP, and 0.06 to 8.0 for PCP. The detection limits were 0.008 μM for 2-CP, 0.002 μM for 2,4-DCP, and 0.01 μM for PCP, respectively. The method was successfully applied for the determination of CPs in waste water with satisfactory recoveries. This ZnSe–CTAB electrode system provides operational access to design environment-friendly CPs sensors

Carbon nanomaterial based electrochemical sensors for biogenic amines

International Nuclear Information System (INIS)

Yang, Xiao; He, Xiulan; Li, Fangping; Fei, Junjie; Feng, Bo; Ding, Yonglan

2013-01-01

This review describes recent advances in the use of carbon nanomaterials for electroanalytical detection of biogenic amines (BAs). It starts with a short introduction into carbon nanomaterials such as carbon nanotubes, graphene, nanodiamonds, carbon nanofibers, fullerenes, and their composites. Next, electrochemical sensing schemes are discussed for various BAs including dopamine, serotonin, epinephrine, norepinephrine, tyramine, histamine and putrescine. Examples are then given for methods for simultaneous detection of various BAs. Finally, we discuss the current and future challenges of carbon nanomaterial-based electrochemical sensors for BAs. The review contains 175 references. (author)

Poly arginine-graphene quantum dots as a biocompatible and non-toxic nanocomposite: Layer-by-layer electrochemical preparation, characterization and non-invasive malondialdehyde sensory application in exhaled breath condensate

Energy Technology Data Exchange (ETDEWEB)

Hasanzadeh, Mohammad, E-mail: hasanzadehm@tbzmed.ac.ir [Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz 51664 (Iran, Islamic Republic of); Mokhtari, Fozieh [Pharmaceutical Analysis Research Center, Tabriz University of Medical Sciences, Tabriz (Iran, Islamic Republic of); Department of Biochemistry, Higher Education Institute of Rab-Rashid, Tabriz (Iran, Islamic Republic of); Shadjou, Nasrin [Department of Nanochemistry, Nano Technology Research Center, Urmia University, Urmia 57154 (Iran, Islamic Republic of); Department of Nano Technology, Faculty of Science, Urmia University, Urmia 57154 (Iran, Islamic Republic of); Eftekhari, Aziz [Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tabriz University of Medical Sciences, 51664-14766 Tabriz (Iran, Islamic Republic of); Mokhtarzadeh, Ahad [Department of Biochemistry, Higher Education Institute of Rab-Rashid, Tabriz (Iran, Islamic Republic of); School of Medicine, Gonabad University of Medical Sciences, Gonabad (Iran, Islamic Republic of); Jouyban-Gharamaleki, Vahid [Department of Mechatronic Engineering, International Campus, University of Tabriz, Tabriz (Iran, Islamic Republic of); Mahboob, Soltanali [Department of Biochemistry, Higher Education Institute of Rab-Rashid, Tabriz (Iran, Islamic Republic of)

2017-06-01

This study reports on the electropolymerization of a low toxic and biocompatible polymer with entitle poly arginine-graphene quantum dots (PARG-GQDs) as a novel strategy for surface modification of glassy carbon (GC) surface and preparation a new interface for biomedical application. The fabrication of PARG-GQDs on GCE was performed using Layer-by-layer regime. Scanning electron microscopy (SEM) was confirmed dispersion of GQDs on the surface of PARG which lead to increase of surface coverage of PARG. The redox behavior of prepared sensor was then characterized by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry (CHA), square wave voltammetry (SWV), linear sweep voltammetry (LSV). The electroactivity of PARG-GQDs coating towards detection and determination of malondialdehyde (MDA) as one of the most common biomarkers of oxidative stress, was then studied. Then, application of prepared sensor for the detection of MDA in exhaled breath condensate (EBC) is described. Electrochemical based sensor shows the lower limit of quantification (LLOQ) were 0.329 nanomolar. This work is the first report on the integration of GQDs to poly amino acids. Further development can lead to monitoring of MDA or other exhaled breath biomarkers by GQDs functionalized poly amino acids in EBC using electrochemical methods. - Highlights: • Simple and one pot electropolymerization was used to preparation of Poly arginine-graphene quantum dots. • PARG-GQDs-GCE shows an excellent electroactivity towards malondialdehyde. • High sensitivity and efficiency is achieved through a simple method of modification. • MDA electrochemical sensor for a direct evaluation of oxidative stress in EBC media is possible.

Poly arginine-graphene quantum dots as a biocompatible and non-toxic nanocomposite: Layer-by-layer electrochemical preparation, characterization and non-invasive malondialdehyde sensory application in exhaled breath condensate

International Nuclear Information System (INIS)

Hasanzadeh, Mohammad; Mokhtari, Fozieh; Shadjou, Nasrin; Eftekhari, Aziz; Mokhtarzadeh, Ahad; Jouyban-Gharamaleki, Vahid; Mahboob, Soltanali

2017-01-01

This study reports on the electropolymerization of a low toxic and biocompatible polymer with entitle poly arginine-graphene quantum dots (PARG-GQDs) as a novel strategy for surface modification of glassy carbon (GC) surface and preparation a new interface for biomedical application. The fabrication of PARG-GQDs on GCE was performed using Layer-by-layer regime. Scanning electron microscopy (SEM) was confirmed dispersion of GQDs on the surface of PARG which lead to increase of surface coverage of PARG. The redox behavior of prepared sensor was then characterized by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry (CHA), square wave voltammetry (SWV), linear sweep voltammetry (LSV). The electroactivity of PARG-GQDs coating towards detection and determination of malondialdehyde (MDA) as one of the most common biomarkers of oxidative stress, was then studied. Then, application of prepared sensor for the detection of MDA in exhaled breath condensate (EBC) is described. Electrochemical based sensor shows the lower limit of quantification (LLOQ) were 0.329 nanomolar. This work is the first report on the integration of GQDs to poly amino acids. Further development can lead to monitoring of MDA or other exhaled breath biomarkers by GQDs functionalized poly amino acids in EBC using electrochemical methods. - Highlights: • Simple and one pot electropolymerization was used to preparation of Poly arginine-graphene quantum dots. • PARG-GQDs-GCE shows an excellent electroactivity towards malondialdehyde. • High sensitivity and efficiency is achieved through a simple method of modification. • MDA electrochemical sensor for a direct evaluation of oxidative stress in EBC media is possible.

Electrochemically reduced graphene oxide-based electrochemical sensor for the sensitive determination of ferulic acid in A. sinensis and biological samples

Energy Technology Data Exchange (ETDEWEB)

Liu, Linjie [School of Pharmacy, Lanzhou University, Lanzhou 730000 (China); Gou, Yuqiang [Lanzhou Military Command Center for Disease Prevention and Control, Lanzhou 730000 (China); Gao, Xia; Zhang, Pei; Chen, Wenxia; Feng, Shilan [School of Pharmacy, Lanzhou University, Lanzhou 730000 (China); Hu, Fangdi, E-mail: hufd@lzu.edu.cn [School of Pharmacy, Lanzhou University, Lanzhou 730000 (China); Li, Yingdong, E-mail: lydj412@163.com [Gansu College of Tradition Chinese Medicine, Lanzhou 730000 (China)

2014-09-01

An electrochemically reduced graphene oxide (ERGO) modified glassy carbon electrode (GCE) was used as a new voltammetric sensor for the determination of ferulic acid (FA). The morphology and microstructure of the modified electrodes were characterized by scanning electron microscopy (SEM) and Raman spectroscopy analysis, and the electrochemical effective surface areas of the modified electrodes were also calculated by chronocoulometry method. Sensing properties of the electrochemical sensor were investigated by means of cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was found that ERGO was electrodeposited on the surface of GCE by using potentiostatic method. The proposed electrode exhibited electrocatalytic activity to the redox of FA because of excellent electrochemical properties of ERGO. The transfer electron number (n), electrode reaction rate constant (k{sub s}) and electron-transfer coefficient (α) were calculated as 1.12, 1.24 s{sup −1}, and 0.40, respectively. Under the optimized conditions, the oxidation peak current was proportional to FA concentration at 8.49 × 10{sup −8} mol L{sup −1} to 3.89 × 10{sup −5} mol L{sup −1} with detection limit of 2.06 × 10{sup −8} mol L{sup −1}. This fabricated sensor also displayed acceptable reproducibility, long-term stability, and high selectivity with negligible interferences from common interfering species. The voltammetric sensor was successfully applied to detect FA in A. sinensis and biological samples with recovery values in the range of 99.91%-101.91%. - Highlights: • A novel ERGO–based electrochemical sensor of FA was successfully fabricated by using one-step electrodeposition method. • The electrode reaction was an adsorption–diffusion mixed controlled process. • The low detection limit with good selectivity and sensitivity were obtained. • This method was applied for the determination of FA in A. sinensis and biological samples.

3D printed stretchable capacitive sensors for highly sensitive tactile and electrochemical sensing

Science.gov (United States)

Li, Kai; Wei, Hong; Liu, Wenguang; Meng, Hong; Zhang, Peixin; Yan, Chaoyi

2018-05-01

Developments of innovative strategies for the fabrication of stretchable sensors are of crucial importance for their applications in wearable electronic systems. In this work, we report the successful fabrication of stretchable capacitive sensors using a novel 3D printing method for highly sensitive tactile and electrochemical sensing applications. Unlike conventional lithographic or templated methods, the programmable 3D printing technique can fabricate complex device structures in a cost-effective and facile manner. We designed and fabricated stretchable capacitive sensors with interdigital and double-vortex designs and demonstrated their successful applications as tactile and electrochemical sensors. Especially, our stretchable sensors exhibited a detection limit as low as 1 × 10-6 M for NaCl aqueous solution, which could have significant potential applications when integrated in electronics skins.

Iron-Based Nanomaterials/Graphene Composites for Advanced Electrochemical Sensors

Directory of Open Access Journals (Sweden)

Kaveh Movlaee

2017-11-01

Full Text Available Iron oxide nanostructures (IONs in combination with graphene or its derivatives—e.g., graphene oxide and reduced graphene oxide—hold great promise toward engineering of efficient nanocomposites for enhancing the performance of advanced devices in many applicative fields. Due to the peculiar electrical and electrocatalytic properties displayed by composite structures in nanoscale dimensions, increasing efforts have been directed in recent years toward tailoring the properties of IONs-graphene based nanocomposites for developing more efficient electrochemical sensors. In the present feature paper, we first reviewed the various routes for synthesizing IONs-graphene nanostructures, highlighting advantages, disadvantages and the key synthesis parameters for each method. Then, a comprehensive discussion is presented in the case of application of IONs-graphene based composites in electrochemical sensors for the determination of various kinds of (biochemical substances.

Iron-Based Nanomaterials/Graphene Composites for Advanced Electrochemical Sensors

Science.gov (United States)

Movlaee, Kaveh; Ganjali, Mohmmad Reza; Norouzi, Parviz

2017-01-01

Iron oxide nanostructures (IONs) in combination with graphene or its derivatives—e.g., graphene oxide and reduced graphene oxide—hold great promise toward engineering of efficient nanocomposites for enhancing the performance of advanced devices in many applicative fields. Due to the peculiar electrical and electrocatalytic properties displayed by composite structures in nanoscale dimensions, increasing efforts have been directed in recent years toward tailoring the properties of IONs-graphene based nanocomposites for developing more efficient electrochemical sensors. In the present feature paper, we first reviewed the various routes for synthesizing IONs-graphene nanostructures, highlighting advantages, disadvantages and the key synthesis parameters for each method. Then, a comprehensive discussion is presented in the case of application of IONs-graphene based composites in electrochemical sensors for the determination of various kinds of (bio)chemical substances. PMID:29168771

Electrochemical Impedance Spectroscopic Analysis of RuO2 Based Thick Film pH Sensors

International Nuclear Information System (INIS)

Manjakkal, Libu; Djurdjic, Elvira; Cvejin, Katarina; Kulawik, Jan; Zaraska, Krzysztof; Szwagierczak, Dorota

2015-01-01

The conductimetric interdigitated thick film pH sensors based on RuO 2 were fabricated and their electrochemical reactions with solutions of different pH values were studied by electrochemical impedance spectroscopy (EIS) technique. The microstructural properties and composition of the sensitive films were examined by scanning electron microscopy, X-ray energy dispersive spectroscopy and Raman spectroscopy. The EIS analysis of the sensor was carried out in the frequency range 10 mHz–2 MHz for pH values of test solutions 2–12. The electrical parameters of the sensor were found to vary with changing pH. The conductance and capacitance of the film were distinctly dependent on pH in the low frequency range. The Nyquist and Bode plots derived from the impedance data for the metal oxide thick film pH sensor provided information about the underlying electrochemical reactions

Preparation and characterization of porphyrin-polythiophene stacked films as prepared by electrochemical method under stirring condition

International Nuclear Information System (INIS)

Sugawa, Kosuke; Akiyama, Tsuyoshi; Yamada, Sunao

2008-01-01

Porphyrin-polythiophene (pTh) stacked films consisting of meso-tetrathienylporphyrin (TThP) and bithiophene (BiTh) were prepared on transparent indium-tin-oxide (ITO) electrodes by sequential electrochemical scanning of applied potential between 0 and + 2 V vs Ag wire in the electrolyte solution of BiTh and TThP under stirring condition. First, the pTh films were prepared by electrochemical polymerization and then TThP was incorporated into the as-prepared pTh film by subsequent electrochemical scanning as described above in the TThP solution. The operation of solution stirring during electrochemical scanning achieved the formation of robust stacked films. UV/Vis and fluorescence spectra confirmed that the amount of TThP moiety increased with increasing the number of electrochemical scanning cycles in the TThP solution. In order to evaluate the incorporation profile of TThP, surface analyses and depth profiles of stacked films were carried out by XPS spectroscopy. The results suggested that all films formed porphyrin-polythiophene stacked structure precisely, and that TThP was exclusively incorporated around the outermost region of the pTh film

Novel Ag@TiO2 nanocomposite synthesized by electrochemically active biofilm for nonenzymatic hydrogen peroxide sensor.

Science.gov (United States)

Khan, Mohammad Mansoob; Ansari, Sajid Ali; Lee, Jintae; Cho, Moo Hwan

2013-12-01

A novel nonenzymatic sensor for H2O2 was developed based on an Ag@TiO2 nanocomposite synthesized using a simple and cost effective approach with an electrochemically active biofilm. The optical, structural, morphological and electrochemical properties of the as-prepared Ag@TiO2 nanocomposite were examined by UV-vis spectroscopy, X-ray diffraction, transmission electron microscopy and cyclic voltammetry (CV). The Ag@TiO2 nanocomposite was fabricated on a glassy carbon electrode (GCE) and their electrochemical performance was analyzed by CV, differential pulse voltammetry and electrochemical impedance spectroscopy. The Ag@TiO2 nanocomposite modified GCE (Ag@TiO2/GCE) displayed excellent performance towards H2O2 sensing at -0.73 V in the linear response range from 0.83 μM to 43.3 μM, within a detection limit and sensitivity of 0.83 μM and ~65.2328±0.01 μA μM(-1) cm(-2), respectively. In addition, Ag@TiO2/GCE exhibited good operational reproducibility and long term stability. © 2013.

Enhanced host–guest electrochemical recognition of herbicide MCPA using a b-cyclodextrin carbon nanotube sensor

OpenAIRE

Rahemi, V.; Vandamme, J.J.; Garrido, J.M.P.J.; Borges, F.; Brett, C.M.A.; Garrido, E.M.P.J.

2012-01-01

An electrochemical sensor for the determination of the chlorophenoxy herbicide MCPA has been developed, based on a combination of multi-walled carbon nanotubes with incorporated b-cyclodextrin and a polyaniline film modified glassy carbon electrode. The proposed molecular host–guest recogni-tion based sensor has a high electrochemical sensitivity for the determination of MCPA. The electrochemical behaviour of MCPA at the chemically modified electrode was investigated in detail by cyclic volta...

One-step electrochemical deposition of a graphene-ZrO₂ nanocomposite: Preparation, characterization and application for detection of organophosphorus agents

Energy Technology Data Exchange (ETDEWEB)

Du, Dan; Liu, Juan; Zhang, Xiao-Yan; Cui, Xiao-Li; Lin, Yuehe

2011-04-27

This paper described the preparation, characterization, and electrochemical properties of a graphene-ZrO₂ nanocomposite (GZN) and its application for both the enrichment and detection of methyl parathion (MP). GZN was fabricated using electrochemical deposition and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), which showed the successful formation of nanocomposites. Due to the strong affinity to the phosphoric group and the fast electron-transfer kinetics of GZN, both the extraction and electrochemical detection of organophosphorus (OP) agents at the same GZN modified electrochemical sensor was possible. The combination of solid-phase extraction and stripping voltammetric analysis allowed fast, sensitive, and selective determination of MP in garlic samples. The stripping response was highly linear over the MP concentrations ranging from 0.5 ng mL^-1 to 100 ng mL^-1, with a detection limit of 0.1 ng mL^-1. This new nanocomposite-based electrochemical sensor provides an opportunity to develop a field-deployable, sensitive, and quantitative method for monitoring exposure to OPs.

Carbon nanotube/polymer composite electrodes for flexible, attachable electrochemical DNA sensors.

Science.gov (United States)

Li, Jianfeng; Lee, Eun-Cheol

2015-09-15

All-solution-processed, easily-made, flexible multi-walled carbon nanotube (MWCNT)/polydimethylsiloxane (PDMS)-based electrodes were fabricated and used for electrochemical DNA sensors. These electrodes could serve as a recognition layer for DNA, without any surface modification, through π-π interactions between the MWCNTs and DNA, greatly simplifying the fabrication process for DNA sensors. The electrodes were directly connected to an electrochemical analyzer in the differential pulse voltammetry (DPV) and cyclic voltammetry (CV) measurements, where methylene blue was used as a redox indicator. Since neither functional groups nor probe DNA were immobilized on the surfaces of the electrodes, the sensor can be easily regenerated by washing these electrodes with water. The limit of detection was found to be 1.3 × 10(2)pM (S/N=3), with good DNA sequence differentiation ability. Fast fabrication of a DNA sensor was also achieved by cutting and attaching the MWCNT-PDMS composite electrodes at an analyte solution-containable region. Our results pave the way for developing user-fabricated easily attached DNA sensors at low costs. Copyright © 2015 Elsevier B.V. All rights reserved.

Carbon Nanomaterials Based Electrochemical Sensors/Biosensors for the Sensitive Detection of Pharmaceutical and Biological Compounds

Directory of Open Access Journals (Sweden)

Bal-Ram Adhikari

2015-09-01

Full Text Available Electrochemical sensors and biosensors have attracted considerable attention for the sensitive detection of a variety of biological and pharmaceutical compounds. Since the discovery of carbon-based nanomaterials, including carbon nanotubes, C60 and graphene, they have garnered tremendous interest for their potential in the design of high-performance electrochemical sensor platforms due to their exceptional thermal, mechanical, electronic, and catalytic properties. Carbon nanomaterial-based electrochemical sensors have been employed for the detection of various analytes with rapid electron transfer kinetics. This feature article focuses on the recent design and use of carbon nanomaterials, primarily single-walled carbon nanotubes (SWCNTs, reduced graphene oxide (rGO, SWCNTs-rGO, Au nanoparticle-rGO nanocomposites, and buckypaper as sensing materials for the electrochemical detection of some representative biological and pharmaceutical compounds such as methylglyoxal, acetaminophen, valacyclovir, β-nicotinamide adenine dinucleotide hydrate (NADH, and glucose. Furthermore, the electrochemical performance of SWCNTs, rGO, and SWCNT-rGO for the detection of acetaminophen and valacyclovir was comparatively studied, revealing that SWCNT-rGO nanocomposites possess excellent electrocatalytic activity in comparison to individual SWCNT and rGO platforms. The sensitive, reliable and rapid analysis of critical disease biomarkers and globally emerging pharmaceutical compounds at carbon nanomaterials based electrochemical sensor platforms may enable an extensive range of applications in preemptive medical diagnostics.

Electrochemical Carbon Dioxide Sensor for Plant Production Environments, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The aim of this proposal is to develop a low power consuming solid polymer electrolyte based, miniaturized electrochemical CO2 sensor that can continuously,...

Electrochemical Carbon Dioxide Sensor for Plant Production Environments, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The aim of this proposal is to develop a low power consuming solid polymer electrolyte based, miniaturized electrochemical CO2 sensor that can continuously,...

Characterization of an electrochemical mercury sensor using alternating current, cyclic, square wave and differential pulse voltammetry

International Nuclear Information System (INIS)

Guerreiro, Gabriela V.; Zaitouna, Anita J.; Lai, Rebecca Y.

2014-01-01

Graphical abstract: -- Highlights: •An electrochemical Hg(II) sensor based on T–Hg(II)–T sensing motif was fabricated. •A methylene blue-modified DNA probe was used to fabricate the sensor. •Sensor performance was evaluated using ACV, CV, SWV, and DPV. •The sensor behaves as a “signal-off” sensor in ACV and CV. •The sensor behaves as either a “signal-on” or “signal-off” sensor in SWV and DPV. -- Abstract: Here we report the characterization of an electrochemical mercury (Hg 2+ ) sensor constructed with a methylene blue (MB)-modified and thymine-containing linear DNA probe. Similar to the linear probe electrochemical DNA sensor, the resultant sensor behaved as a “signal-off” sensor in alternating current voltammetry and cyclic voltammetry. However, depending on the applied frequency or pulse width, the sensor can behave as either a “signal-off” or “signal-on” sensor in square wave voltammetry (SWV) and differential pulse voltammetry (DPV). In SWV, the sensor showed “signal-on” behavior at low frequencies and “signal-off” behavior at high frequencies. In DPV, the sensor showed “signal-off” behavior at short pulse widths and “signal-on” behavior at long pulse widths. Independent of the sensor interrogation technique, the limit of detection was found to be 10 nM, with a linear dynamic range between 10 nM and 500 nM. In addition, the sensor responded to Hg 2+ rather rapidly; majority of the signal change occurred in 2+ , which has not been previously reported. More importantly, the observed “switching” behavior in SWV and DPV is potentially generalizable and should be applicable to most sensors in this class of dynamics-based electrochemical biosensors

A graphene-based electrochemical sensor for sensitive detection of paracetamol

Energy Technology Data Exchange (ETDEWEB)

Kang, Xinhuang; Wang, Jun; Wu, Hong; Liu, Jun; Aksay, Ilhan A.; Lin, Yuehe

2010-05-15

An electrochemical sensor based on the electrocatalytic activity of functionalized graphene for sensitive detection of paracetamol is presented. The electrochemical behaviors of paracetamol on graphene-modified glassy carbon electrodes (GCEs) were investigated by cyclic voltammetry and square-wave voltammetry. The results showed that the graphene-modified electrode exhibited excellent electrocatalytic activity to paracetamol. A quasi-reversible redox process of paracetamol at the modified electrode was obtained, and the over-potential of paracetamol decreased significantly compared with that at the bare GCE. Such electrocatalytic behavior of graphene is attributed to its unique physical and chemical properties, e.g., subtle electronic characteristics, attractive π–π interaction, and strong adsorptive capability. The sensor shows great promise for simple, sensitive, and quantitative detection of paracetamol.

An electrochemical approach: Switching Structures of rare earth metal Praseodymium hexacyanoferrate and its application to sulfite sensor in Red Wine

International Nuclear Information System (INIS)

Devadas, Balamurugan; Sivakumar, Mani; Chen, Shen Ming; Cheemalapati, Srikanth

2015-01-01

Graphical abstract: Nucleation and growth of PrHCF and its application to sulfite oxidation in wine samples. - Highlights: • Electrochemical synthesis of PrHCF. • Switching structures of PrHCF. • Sulfite electrochemical sensor. • Wide linear range and low limit of detection. • Real sample application. - Abstract: Herein, we report a shape-controlled preparation of Praseodymium hexacyanoferrate (PrHCF) using a simple electrochemical technique. The electrochemically fabricated PrHCF modified glassy carbon electrodes (GCE) shows an excellent electrocatalytic activity towards sulfite oxidation. The morphology of PrHCF particles were controlled by carefully changing various synthesis conditions including electrochemical technique (cyclic voltammetry, amperometry and chemical), cations in the supporting electrolyte (K + , Na + , Li + and H + ), deposition cycles, molar ratio of precursors, and applied potential (-.2,0 and 0.2 V). The morphologies of the PrHCF was elucidated using scanning electron microscopy (SEM). The as-synthesized PrHCF was characterized using X-ray diffraction pattern (XRD), Infra-red (IR) and energy dispersive X-ray spectroscopy (EDX). The electrochemical oxidation of sulfite on PrHCF modified GCE was investigated using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The sensitivity of the as-developed sulfite sensor was determined to be 0.036 μA μM −1 cm −2 . The low limit of detection was determined to be 2.15 μM. The real time application of PrHCF modified GCE was confirmed through the determination of sulfite from red wine and tap water samples

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

Directory of Open Access Journals (Sweden)

Ademar Wong

2017-03-01

Full Text Available 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.

Electrochemical sensors in breast cancer diagnostics and follow-up

Directory of Open Access Journals (Sweden)

Raquel Marques

2015-12-01

Full Text Available Purpose: The detection of tumor biomarkers can have a major contribution to the management of breast cancer. So far the only serum biomarker in current use in breast cancer is the cancer antigen 15-3 (CA15-3. This biomarker is used in advanced breast cancer to monitor patients and to help to identify treatment failure. The human epidermal growth factor receptor 2 (HER 2 is another biomarker whose characterization is usually made in tissue samples from primary tumour or metastasis and has been used as a prognostic factor but mainly as a target in immunotherapy treatment. Some previous studies suggest that the detection of the extracellular domain of HER2 (HER2-ECD in blood can be a prognostic factor, with even better results than its detection in tissue. Recent techniques for circulating protein biomarker detection use immunoassays, but some are, for example, not sufficiently sensitive for the detection of low biomarker concentrations. To overcome some of these problems, electrochemical (biosensors, and especially the ones using voltammetric detection, can be adequate alternatives because of their high selectivity and sensitivity which allows early detection of many diseases. Furthermore, electrochemical (biosensors are excellent to be included into point-of-care devices due to their fast response, simplicity, low cost, easy miniaturization and integration into automatic systems. Another advantage is the possibility of combining individual sensors into multiplexed detection systems. Like this they can provide fast recording of biomarker profiles of tumours which can play an important role in early detection and personalized medicine.Methods: Both individual as well as multiplexed electrochemical immunosensors were developed for the detection of CA15-3 and HER2-ECD. For this purpose a sandwich immunoassay was employed and the analytical signal was based on the voltammetric detection of enzymatically deposited silver. Screen-printed carbon

nanocomposites chitosan /clay for electrochemical sensors

International Nuclear Information System (INIS)

Braga, Carla R. Costa; Melo, Frank M. Araujo de; Costa, Gilmara M. Silva; Silva, Suedina M. Lima

2009-01-01

This study was performed to obtain films of nanocomposites chitosan/bentonite and chitosan/montmorillonite intercalation by the technique of solution in the proportions of 5:1 and 10:1. The nanocomposites were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and the nanocomposites Chitosan/montmorillonite also were characterized by thermogravimetric analysis (TG). The results indicated that the feasibility of obtaining films of nanocomposites exfoliate. Among the suggested applications for films developed in this study includes them use for electrochemical sensors. (author)

Electro-chemical sensors, sensor arrays and circuits

Science.gov (United States)

Katz, Howard E.; Kong, Hoyoul

2014-07-08

An electro-chemical sensor includes a first electrode, a second electrode spaced apart from the first electrode, and a semiconductor channel in electrical contact with the first and second electrodes. The semiconductor channel includes a trapping material. The trapping material reduces an ability of the semiconductor channel to conduct a current of charge carriers by trapping at least some of the charge carriers to localized regions within the semiconductor channel. The semiconductor channel includes at least a portion configured to be exposed to an analyte to be detected, and the trapping material, when exposed to the analyte, interacts with the analyte so as to at least partially restore the ability of the semiconductor channel to conduct the current of charge carriers.

Preparation, Modification, Characterization, and Biosensing Application of Nanoporous Gold Using Electrochemical Techniques.

Science.gov (United States)

Bhattarai, Jay K; Neupane, Dharmendra; Nepal, Bishal; Mikhaylov, Vasilii; Demchenko, Alexei V; Stine, Keith J

2018-03-16

Nanoporous gold (np-Au), because of its high surface area-to-volume ratio, excellent conductivity, chemical inertness, physical stability, biocompatibility, easily tunable pores, and plasmonic properties, has attracted much interested in the field of nanotechnology. It has promising applications in the fields of catalysis, bio/chemical sensing, drug delivery, biomolecules separation and purification, fuel cell development, surface-chemistry-driven actuation, and supercapacitor design. Many chemical and electrochemical procedures are known for the preparation of np-Au. Recently, researchers are focusing on easier and controlled ways to tune the pores and ligaments size of np-Au for its use in different applications. Electrochemical methods have good control over fine-tuning pore and ligament sizes. The np-Au electrodes that are prepared using electrochemical techniques are robust and are easier to handle for their use in electrochemical biosensing. Here, we review different electrochemical strategies for the preparation, post-modification, and characterization of np-Au along with the synergistic use of both electrochemistry and np-Au for applications in biosensing.

Characterization of an electrochemical mercury sensor using alternating current, cyclic, square wave and differential pulse voltammetry

Energy Technology Data Exchange (ETDEWEB)

Guerreiro, Gabriela V.; Zaitouna, Anita J.; Lai, Rebecca Y., E-mail: rlai2@unl.edu

2014-01-31

Graphical abstract: -- Highlights: •An electrochemical Hg(II) sensor based on T–Hg(II)–T sensing motif was fabricated. •A methylene blue-modified DNA probe was used to fabricate the sensor. •Sensor performance was evaluated using ACV, CV, SWV, and DPV. •The sensor behaves as a “signal-off” sensor in ACV and CV. •The sensor behaves as either a “signal-on” or “signal-off” sensor in SWV and DPV. -- Abstract: Here we report the characterization of an electrochemical mercury (Hg{sup 2+}) sensor constructed with a methylene blue (MB)-modified and thymine-containing linear DNA probe. Similar to the linear probe electrochemical DNA sensor, the resultant sensor behaved as a “signal-off” sensor in alternating current voltammetry and cyclic voltammetry. However, depending on the applied frequency or pulse width, the sensor can behave as either a “signal-off” or “signal-on” sensor in square wave voltammetry (SWV) and differential pulse voltammetry (DPV). In SWV, the sensor showed “signal-on” behavior at low frequencies and “signal-off” behavior at high frequencies. In DPV, the sensor showed “signal-off” behavior at short pulse widths and “signal-on” behavior at long pulse widths. Independent of the sensor interrogation technique, the limit of detection was found to be 10 nM, with a linear dynamic range between 10 nM and 500 nM. In addition, the sensor responded to Hg{sup 2+} rather rapidly; majority of the signal change occurred in <20 min. Overall, the sensor retains all the characteristics of this class of sensors; it is reagentless, reusable, sensitive, specific and selective. This study also highlights the feasibility of using a MB-modified probe for real-time sensing of Hg{sup 2+}, which has not been previously reported. More importantly, the observed “switching” behavior in SWV and DPV is potentially generalizable and should be applicable to most sensors in this class of dynamics-based electrochemical biosensors.

Highly-sensitive and rapid detection of ponceau 4R and tartrazine in drinks using alumina microfibers-based electrochemical sensor.

Science.gov (United States)

Zhang, Yuanyuan; Hu, Lintong; Liu, Xin; Liu, Bifeng; Wu, Kangbing

2015-01-01

Alumina microfibers were prepared and used to construct an electrochemical sensor for simultaneous detection of ponceau 4R and tartrazine. In pH 3.6 acetate buffer, two oxidation waves at 0.67 and 1.01 V were observed. Due to porous structures and large surface area, alumina microfibers exhibited high accumulation efficiency to ponceau 4R and tartrazine, and increased their oxidation signals remarkably. The oxidation mechanisms were studied, and their oxidation reaction involved one electron and one proton. The influences of pH value, amount of alumina microfibers and accumulation time were examined. As a result, a highly-sensitive, rapid and simple electrochemical method was newly developed for simultaneous detection of ponceau 4R and tartrazine. The detection limits were 0.8 and 2.0 nM for ponceau 4R and tartrazine. This new sensor was used in different drink samples, and the results consisted with the values that obtained by high-performance liquid chromatography. Copyright © 2014 Elsevier Ltd. All rights reserved.

Reproducible preparation of a stable polypyrrole-coated-silver nanoparticles decorated polypyrrole-coated-polycaprolactone-nanofiber-based cloth electrode for electrochemical sensor application

Science.gov (United States)

Li, Li; Wang, Xiaoping; Liu, Guiting; Wang, Zhenzhen; Wang, Feng; Guo, Xiaoyu; Wen, Ying; Yang, Haifeng

2015-11-01

A piece of conductive cloth has been successfully constructed from polypyrrole-coated silver nanoparticle (Ag@PPy) composites decorated on electrospun polycaprolactone (PCL) nanofibers that formed the core-shell structure of Ag@PPy/PCL@PPy via a photo-induced one-step redox reaction. The photochemical reaction method both accelerated the rate of formation of silver nanoparticles (Ag NPs) and enhanced the dispersion of Ag NPs at the surface of PCL@PPy film. The resulting Ag@PPy/PCL@PPy-based cloth was flexible enough to be cut and pasted onto a glass carbon electrode for the preparation of a biosensor. The resulting biosensor showed good electrochemical activity toward the reduction of H2O2 with low detection limit down to 1 μM (S/N = 3) and wide linear detection ranging from 0.01 mM to 3.5 mM (R2 = 0.990). This sensor has been applied to detect the trace H2O2 residual in milk. The cloth electrode has been proved to exhibit long-term stability, high selectivity, and excellent reproducibility.

Reproducible preparation of a stable polypyrrole-coated-silver nanoparticles decorated polypyrrole-coated-polycaprolactone-nanofiber-based cloth electrode for electrochemical sensor application

International Nuclear Information System (INIS)

Li, Li; Wang, Xiaoping; Liu, Guiting; Wang, Zhenzhen; Wang, Feng; Guo, Xiaoyu; Wen, Ying; Yang, Haifeng

2015-01-01

A piece of conductive cloth has been successfully constructed from polypyrrole-coated silver nanoparticle (Ag@PPy) composites decorated on electrospun polycaprolactone (PCL) nanofibers that formed the core–shell structure of Ag@PPy/PCL@PPy via a photo-induced one-step redox reaction. The photochemical reaction method both accelerated the rate of formation of silver nanoparticles (Ag NPs) and enhanced the dispersion of Ag NPs at the surface of PCL@PPy film. The resulting Ag@PPy/PCL@PPy-based cloth was flexible enough to be cut and pasted onto a glass carbon electrode for the preparation of a biosensor. The resulting biosensor showed good electrochemical activity toward the reduction of H 2 O 2 with low detection limit down to 1 μM (S/N = 3) and wide linear detection ranging from 0.01 mM to 3.5 mM (R 2  = 0.990). This sensor has been applied to detect the trace H 2 O 2 residual in milk. The cloth electrode has been proved to exhibit long-term stability, high selectivity, and excellent reproducibility. (paper)

Medical preparation container comprising microwave powered sensor assembly

DEFF Research Database (Denmark)

2016-01-01

The present invention relates to a medical preparation container which comprises a microwave powered sensor assembly. The microwave powered sensor assembly comprises a sensor configured to measure a physical property or chemical property of a medical preparation during its heating in a microwave ...... oven. The microwave powered sensor assembly is configured for harvesting energy from microwave radiation emitted by the microwave oven and energize the sensor by the harvested microwave energy.......The present invention relates to a medical preparation container which comprises a microwave powered sensor assembly. The microwave powered sensor assembly comprises a sensor configured to measure a physical property or chemical property of a medical preparation during its heating in a microwave...

An Electrochemical pH Sensor Based on the Amino-Functionalized Graphene and Polyaniline Composite Film.

Science.gov (United States)

Su, W; Xu, J; Ding, Xianting

2016-12-01

Conventional glass-based pH sensors are usually fragile and space consuming. Herein, a miniature electrochemical pH sensor based on amino-functionalized graphene fragments and polyaniline (NH 2 -G/PANI) composite film is developed via simply one-pot electrochemical polymerization on the ITO-coated glass substrates. Cyclic Voltammetry (CV), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and Raman Spectra are involved to confirm the successful synthesis and to characterize the properties of the NH 2 -G/PANI composite film. The developed electrochemical pH sensor presents fast response, high sensitivity (51.1 mV/pH) and wide detection range when applied to PBS solutions of pH values from 1 to 11. The robust reproducibility and good stability of the developed pH sensors are investigated as well. Compared to the conventional glass-based pH meters, the NH 2 -G/PANI composite film-based pH sensor could be a promising contender for the flexible and miniaturized pH-sensing devices.

Electrochemical hydrogen isotope sensor based on solid electrolytes

International Nuclear Information System (INIS)

Matsumoto, Hiroshige; Hayashi, Hiroyuki; Iwahara, Hiroyasu

2002-01-01

An electrochemical sensor of hydrogen isotopes based on solid electrolytes for determining the hydrogen isotope ratios and/or total hydrogen pressures in gases has been developed. This paper describes the methodology of the hydrogen isotope sensing together with experimental results. When hydrogen isotope gases are introduced to an electrochemical cell using a proton-conducting electrolyte (hydrogen isotope cell), the electromotive force (EMF) of the cell agrees with that theoretically estimated. The EMF signals can be used for the determination of the hydrogen isotope ratio in gases if the total hydrogen pressure is predetermined. By supplementary use of an oxide ion conductor cell, both the ratio and total pressure of the hydrogen isotopes can be simultaneously determined. (author)

Fabrication of highly sensitive gold nanourchins based electrochemical sensor for nanomolar determination of primaquine

International Nuclear Information System (INIS)

Thapliyal, Neeta Bachheti; Chiwunze, Tirivashe Elton; Karpoormath, Rajshekhar; Cherukupalli, Srinivasulu

2017-01-01

A gold nanourchins modified glassy carbon electrode (AuNu/GCE) was developed for the determination of antimalarial drug, primaquine (PQ). The surface of AuNu/GCE was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and cyclic voltammetry (CV). EIS results indicated that the electron transfer process at AuNu/GCE was faster as compared to the bare electrode. The SEM and TEM image confirmed the presence and uniform dispersion of gold nanourchins on the GCE surface. Upon investigating the electrochemical behavior of PQ at AuNu/GCE, the developed sensor was found to exhibit high electrocatalytic activity towards the oxidation of PQ. Under optimal experimental conditions, the sensor showed fast and sensitive current response to PQ over a linear concentration range of 0.01–1 μM and 0.001–1 μM with a detection limit of 3.5 nM and 0.9 nM using differential pulse voltammetry (DPV) and square wave voltammetry (SWV), respectively. The AuNu/GCE showed good selectivity, reproducibility and stability. Further, the developed sensor was successfully applied to determine the drug in human urine samples and pharmaceutical formulations demonstrating its analytical applicability in clinical analysis as well as quality control. The proposed method thus provides a promising alternative in routine sensing of PQ as well as promotes the application of gold nanourchins in electrochemical sensors. - Graphical abstract: A gold nanourchins modified glassy carbon electrode was fabricated and used as an electrochemical sensing platform for the determination of primaquine. Display Omitted - Highlights: • Gold nanourchins based electrochemical sensor for determination of primaquine • A detection limit of 0.9 nM was obtained using square wave voltammetry. • Proposed method was applied to quantify the drug in tablet and human urine samples. • Fast, simple and low-cost method for trace analysis of

Fabrication of highly sensitive gold nanourchins based electrochemical sensor for nanomolar determination of primaquine

Energy Technology Data Exchange (ETDEWEB)

Thapliyal, Neeta Bachheti, E-mail: thapliyaln@ukzn.ac.za; Chiwunze, Tirivashe Elton; Karpoormath, Rajshekhar, E-mail: karpoormath@ukzn.ac.za; Cherukupalli, Srinivasulu

2017-05-01

A gold nanourchins modified glassy carbon electrode (AuNu/GCE) was developed for the determination of antimalarial drug, primaquine (PQ). The surface of AuNu/GCE was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and cyclic voltammetry (CV). EIS results indicated that the electron transfer process at AuNu/GCE was faster as compared to the bare electrode. The SEM and TEM image confirmed the presence and uniform dispersion of gold nanourchins on the GCE surface. Upon investigating the electrochemical behavior of PQ at AuNu/GCE, the developed sensor was found to exhibit high electrocatalytic activity towards the oxidation of PQ. Under optimal experimental conditions, the sensor showed fast and sensitive current response to PQ over a linear concentration range of 0.01–1 μM and 0.001–1 μM with a detection limit of 3.5 nM and 0.9 nM using differential pulse voltammetry (DPV) and square wave voltammetry (SWV), respectively. The AuNu/GCE showed good selectivity, reproducibility and stability. Further, the developed sensor was successfully applied to determine the drug in human urine samples and pharmaceutical formulations demonstrating its analytical applicability in clinical analysis as well as quality control. The proposed method thus provides a promising alternative in routine sensing of PQ as well as promotes the application of gold nanourchins in electrochemical sensors. - Graphical abstract: A gold nanourchins modified glassy carbon electrode was fabricated and used as an electrochemical sensing platform for the determination of primaquine. Display Omitted - Highlights: • Gold nanourchins based electrochemical sensor for determination of primaquine • A detection limit of 0.9 nM was obtained using square wave voltammetry. • Proposed method was applied to quantify the drug in tablet and human urine samples. • Fast, simple and low-cost method for trace analysis of

Effect of Amine Adlayer on Electrochemical Uric Acid Sensor Conducted on Electrochemically Reduced Graphene Oxide

Energy Technology Data Exchange (ETDEWEB)

Park, Sumi; Kim, Kyuwon [Incheon National University, Incheon (Korea, Republic of)

2016-03-15

The electrochemical biosensing efficiency of uric acid (UA) detection on an electrochemically reduced graphene oxide (ERGO)-decorated electrode surface was studied by using various amine linkers used to immobilize ERGO. The amine linkers aminoethylphenyldiazonium , 2,2'-(ethylenedioxy)bis(ethylamine), 3-aminopro-pyltriethoxysilane, and polyethyleneimine were coated on indium-tin-oxide electrode surfaces through chemical or electrochemical deposition methods. ERGO-decorated surfaces were prepared by the electrochemical reduction of graphene oxide (GO), which was immobilized on the amine-coated electrode surfaces through the electrostatic interaction between GO and the ammonium ion of the linker on the surface. We monitored the sensing results of electrochemical UA detection with differential pulse voltammetry. The ERGO-modified surface presented electrocatalytic oxidation of UA and ascorbic acid. Among the different amines tested, 3-aminopropyltriethoxysilane provided the best biosensing performance in terms of sensitivity and reproducibility.

Effect of Amine Adlayer on Electrochemical Uric Acid Sensor Conducted on Electrochemically Reduced Graphene Oxide

International Nuclear Information System (INIS)

Park, Sumi; Kim, Kyuwon

2016-01-01

The electrochemical biosensing efficiency of uric acid (UA) detection on an electrochemically reduced graphene oxide (ERGO)-decorated electrode surface was studied by using various amine linkers used to immobilize ERGO. The amine linkers aminoethylphenyldiazonium , 2,2'-(ethylenedioxy)bis(ethylamine), 3-aminopro-pyltriethoxysilane, and polyethyleneimine were coated on indium-tin-oxide electrode surfaces through chemical or electrochemical deposition methods. ERGO-decorated surfaces were prepared by the electrochemical reduction of graphene oxide (GO), which was immobilized on the amine-coated electrode surfaces through the electrostatic interaction between GO and the ammonium ion of the linker on the surface. We monitored the sensing results of electrochemical UA detection with differential pulse voltammetry. The ERGO-modified surface presented electrocatalytic oxidation of UA and ascorbic acid. Among the different amines tested, 3-aminopropyltriethoxysilane provided the best biosensing performance in terms of sensitivity and reproducibility.

Preparation, Modification, Characterization, and Biosensing Application of Nanoporous Gold Using Electrochemical Techniques

Directory of Open Access Journals (Sweden)

Jay K. Bhattarai

2018-03-01

Full Text Available Nanoporous gold (np-Au, because of its high surface area-to-volume ratio, excellent conductivity, chemical inertness, physical stability, biocompatibility, easily tunable pores, and plasmonic properties, has attracted much interested in the field of nanotechnology. It has promising applications in the fields of catalysis, bio/chemical sensing, drug delivery, biomolecules separation and purification, fuel cell development, surface-chemistry-driven actuation, and supercapacitor design. Many chemical and electrochemical procedures are known for the preparation of np-Au. Recently, researchers are focusing on easier and controlled ways to tune the pores and ligaments size of np-Au for its use in different applications. Electrochemical methods have good control over fine-tuning pore and ligament sizes. The np-Au electrodes that are prepared using electrochemical techniques are robust and are easier to handle for their use in electrochemical biosensing. Here, we review different electrochemical strategies for the preparation, post-modification, and characterization of np-Au along with the synergistic use of both electrochemistry and np-Au for applications in biosensing.

Online Monitoring of Electrochemical Degradation of Paracetamol through a Biomimetic Sensor

Directory of Open Access Journals (Sweden)

Mariana Calora Quintino de Oliveira

2011-01-01

Full Text Available This paper reports, for the first time, the online monitoring to the electrochemical degradation of the paracetamol using a biomimetic sensor coupled to a Flow Injection Analysis (FIA system. The electrochemical degradation of the drug was carried out in aqueous medium using a flow-by reactor with a DSA anode. The process efficiency was monitored at real time by the biomimetic sensor constructed by modifying a glassy carbon electrode with a Nafion membrane doped with iron tetrapyridinoporphyrazine (FeTPyPz. Simultaneously, we carried out off-line analysis by liquid chromatography (HPLC during the experiments in order to validate the proposed system. In addition, to investigate the degradation products of the paracetamol electrolysis, we used the techniques of UPLC/MS and GC/MS.

Non-aqueous electrochemical deposition of lead zirconate titanate films for flexible sensor applications

Science.gov (United States)

Joseph, Sherin; Kumar, A. V. Ramesh; John, Reji

2017-11-01

Lead zirconate titanate (PZT) is one of the most important piezoelectric materials widely used for underwater sensors. However, PZTs are hard and non-compliant and hence there is an overwhelming attention devoted toward making it flexible by preparing films on flexible substrates by different routes. In this work, the electrochemical deposition of composition controlled PZT films over flexible stainless steel (SS) foil substrates using non-aqueous electrolyte dimethyl sulphoxide (DMSO) was carried out. Effects of various key parameters involved in electrochemical deposition process such as current density and time of deposition were studied. It was found that a current density of 25 mA/cm2 for 5 min gave a good film. The morphology and topography evaluation of the films was carried out by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively, which showed a uniform morphology with a surface roughness of 2 nm. The PZT phase formation was studied using X-ray diffraction (XRD) and corroborated with Raman spectroscopic studies. The dielectric constant, dielectric loss, hysteresis and I-V characteristics of the film was evaluated.

A Dual Electrochemical Sensor Based on a Test-strip Assay for the Quantitative Determination of Albumin and Creatinine.

Science.gov (United States)

Yasukawa, Tomoyuki; Kiba, Yuya; Mizutani, Fumio

2015-01-01

A dual-electrochemical sensor based on a test-strip assay with immunochemistry and enzyme reactions has been developed for the determination of albumin and creatinine. Each nitrocellulose membrane with an immobilization area of an anti-albumin antibody or three enzymes was prepared in the device with three working electrodes for measuring albumin, creatinine, and ascorbic acid, as well as an Ag/AgCl electrode used as a counter/pseudo-reference electrode. The reactions of three enzymes were initiated by flowing a solution containing creatinine to detect an oxidation current of hydrogen peroxide. A sandwich-type immunocomplex was formed by albumin and antibody labeled with glucose oxidase (GOx). Captured GOx catalyzed the reduction of Fe(CN)6(3-) to Fe(CN)6(4-), which was oxidized electrochemically to determine the captured albumin. The responses for creatinine and albumin increased with the concentrations in millimolar order and over the range 18.75 - 150 μg mL(-1), respectively. The present sensor would be a distinct demonstration for producing quantitative dual-assays for various biomolecules used for clinical diagnoses.

Preparation and electrochemical characterization of MnOOH nanowire-graphene oxide

International Nuclear Information System (INIS)

Wang Lin; Wang Dianlong

2011-01-01

Highlights: → MnOOH nanowire-graphene oxide composites are prepared by hydrothermal reaction in distilled water or 5% ammonia aqueous solution at 130 deg. C, with MnO 2 -graphene oxide composites which are synthesized by a redox reaction between KMnO 4 and graphene oxide. → MnO 2 is deoxidized to MnOOH on graphene oxide through hydrothermal reaction without any extra reductants. → It is found that the electrochemical resistance of MnOOH nanowire-graphene oxide composites decreases and the capacitance increases to 76 F g -1 when hydrothermal reaction is conducted in ammonia aqueous solution. → MnOOH nanowire-graphene oxide composites prepared by hydrothermal reaction in 5% ammonia aqueous solution have excellent capacitance retention ratio at scan rate from 5 mV s -1 to 40 mV s -1 . - Abstract: MnOOH nanowire-graphene oxide composites are prepared by hydrothermal reaction in distilled water or 5% ammonia aqueous solution at 130 deg. C with MnO 2 -graphene oxide composites which are synthesized by a redox reaction between KMnO 4 and graphene oxide. Powder X-ray diffraction (XRD) analyses and energy dispersive X-ray analyses (EDAX) show MnO 2 is deoxidized to MnOOH on graphene oxide through hydrothermal reaction without any extra reductants. The electrochemical capacitance of MnOOH nanowire-graphene oxide composites prepared in 5% ammonia aqueous solution is 76 F g -1 at current density of 0.1 A g -1 . Moreover, electrochemical impedance spectroscopy (EIS) suggests the electrochemical resistance of MnOOH nanowire-graphene oxide composites is reduced when hydrothermal reaction is conducted in ammonia aqueous solution. The relationship between the electrochemical capacitance and the structure of MnOOH nanowire-graphene oxide composites is characterized by cyclic voltammetry (CV) and field emission scanning electron microscopy (FESEM). The results indicate the electrochemical performance of MnOOH nanowire-graphene oxide composites strongly depends on their

Electrochemical sensors for detection of acetylsalicylic acid

OpenAIRE

Šupálková, Veronika; Petřek, Jiří; Havel, Ladislav; Křížková, Soňa; Petrlová, Jitka; Adam, Vojtěch; Potěšil, David; Babula, Petr; Beklová, Miroslava; Horna, Aleš; Kizek, René

2006-01-01

Acetylsalicylic acid ( AcSA), or aspirin, was introduced in the late 1890s and has been used to treat a variety of inflammatory conditions. The aim of this work was to suggest electrochemical sensor for acetylsalicylic detection. Primarily, we utilized square wave voltammetry ( SWV) using both carbon paste electrode ( CPE) and of graphite pencil electrode ( GPE) as working ones to indirect determination of AcSA. The principle of indirect determination of AcSA bases in its hydrolysis on salicy...

Electrochemically induced chemical sensor properties in graphite screen-printed electrodes: The case of a chemical sensor for uranium

International Nuclear Information System (INIS)

Kostaki, Vasiliki T.; Florou, Ageliki B.; Prodromidis, Mamas I.

2011-01-01

Highlights: → Electrochemical treatment endows analytical characteristics to SPEs. → A sensitive chemical sensor for uranium is described. → Performance is due to a synergy between electrochemical treatment and ink's solvents. → The amount of the solvent controls the achievable sensitivity. - Abstract: We report for the first time on the possibility to develop chemical sensors based on electrochemically treated, non-modified, graphite screen-printed electrodes (SPEs). The applied galvanostatic treatment (5 μA for 6 min in 0.1 M H 2 SO 4 ) is demonstrated to be effective for the development of chemical sensors for the determination of uranium in aqueous solutions. A detailed study of the effect of various parameters related to the fabrication of SPEs on the performance of the resulting sensors along with some diagnostic experiments on conventional graphite electrodes showed that the inducible analytical characteristics are due to a synergy between electrochemical treatment and ink's solvents. Indeed, the amount of the latter onto the printed working layer controls the achievable sensitivity. The preconcentration of the analyte was performed in an electroless mode in an aqueous solutions of U(VI), pH 4.6, and then, the accumulated species was reduced by means of a differential pulse voltammetry scan in 0.1 M H 3 BO 3 , pH 3. Under selected experimental conditions, a linear calibration curve over the range 5 x 10 -9 to 10 -7 M U(VI) was constructed. The 3σ limit of detection at a preconcentration time of 30 min, and the relative standard deviation of the method were 4.5 x 10 -9 M U(VI) and >12% (n = 5, 5 x 10 -8 M U(VI)), respectively. The effect of potential interferences was also examined.

Functionalized Multiwalled Carbon Nanotube Electrochemical Sensor for Determination of Anticancer Drug Flutamide

Science.gov (United States)

Farias, Julianna Santos; Zanin, Hudson; Caldas, Adriana Silva; dos Santos, Clenilton Costa; Damos, Flavio Santos; de Cássia Silva Luz, Rita

2017-10-01

An electrochemical sensor based on functionalized multiwalled carbon nanotubes (MWCNTf) has been developed and applied for determination of anticancer drug flutamide in pharmaceutical and artificial urine samples. The electrode was prepared by modifying a glassy carbon electrode with MWCNTf, denoted herein as MWCNTf/GCE. The MWCNTf/GCE electrode exhibited high catalytic activity, high sensitivity, and high stability and was applicable over a wide concentration range for flutamide. The effects of the scan rate, pH, and nature of the electrolyte on the electrochemical behavior of flutamide on the MWCNTf/GCE were investigated. The results showed that this electrode presented the best square-wave voltammetric response to flutamide in Britton-Robinson buffer solution at pH 5.0 at frequency of 50 Hz and amplitude of 0.06 V. The proposed sensor presents a wide linear response range from concentration of 0.1 μmol L-1 up to 1000 μmol L-1 (or 27.6 μg L-1 up to 0.27 g L-1), with limit of detection, limit of quantification, and sensitivity of 0.03 μmol L-1, 0.1 μmol L-1, and 0.30 μA μmol-1 L, respectively. The MWCNTf/GCE electrode was successfully applied for determination of flutamide in pharmaceutical formulations and artificial urine samples, giving results in agreement with those obtained by a comparative method described in literature. A paired Student's t-test revealed no statistical difference between the reference and proposed method at 95% confidence level. The average recovery for fortified samples was 101 ± 1%.

Development of a sensitive electrochemical DNA sensor by 4-aminothiophenol self-assembled on electrodeposited nanogold electrode coupled with Au nanoparticles labeled reporter ssDNA

International Nuclear Information System (INIS)

Li Guangjiu; Liu Lihua; Qi Xiaowei; Guo Yaqing; Sun Wei; Li Xiaolin

2012-01-01

Graphical abstract: - Abstract: A novel and sensitive electrochemical DNA biosensor was fabricated by using the 4-aminothiophenol (4-ATP) self-assembled on electrodeposited gold nanoparticles (NG) modified electrode to anchor capture ssDNA sequences and Au nanoparticles (AuNPs) labeled with reporter ssDNA sequences, which were further coupled with electroactive indicator of hexaammineruthenium (III) ([Ru(NH 3 ) 6 ] 3+ ) to amplify the electrochemical signal of hybridization reaction. Different modified electrodes were prepared and characterized by cyclic voltammetry, scanning electron microscope and electrochemical impedance spectroscopy. By using a sandwich model for the capture of target ssDNA sequences, which was based on the shorter probe ssDNA and AuNPs label reporter ssDNA hybridized with longer target ssDNA, the electrochemical behavior of [Ru(NH 3 ) 6 ] 3+ was monitored by differential pulse voltammetry (DPV). The fabricated electrochemical DNA sensor exhibited good distinguish capacity for the complementary ssDNA sequence and two bases mismatched ssDNA. The dynamic detection range of the target ssDNA sequences was from 1.4 × 10 −11 to 2.0 × 10 −9 mol/L with the detection limit as 9.5 × 10 −12 mol/L (3σ). So in this paper a new electrochemical DNA sensor was designed with gold nanoparticles as the immobilization platform and the signal amplifier simultaneously.

Microfluidic electrochemical sensor for on-line monitoring of aerosol oxidative activity.

Science.gov (United States)

Sameenoi, Yupaporn; Koehler, Kirsten; Shapiro, Jeff; Boonsong, Kanokporn; Sun, Yele; Collett, Jeffrey; Volckens, John; Henry, Charles S

2012-06-27

Particulate matter (PM) air pollution has a significant impact on human morbidity and mortality; however, the mechanisms of PM-induced toxicity are poorly defined. A leading hypothesis states that airborne PM induces harm by generating reactive oxygen species in and around human tissues, leading to oxidative stress. We report here a system employing a microfluidic electrochemical sensor coupled directly to a particle-into-liquid sampler (PILS) system to measure aerosol oxidative activity in an on-line format. The oxidative activity measurement is based on the dithiothreitol (DTT) assay, where, after being oxidized by PM, the remaining reduced DTT is analyzed by the microfluidic sensor. The sensor consists of an array of working, reference, and auxiliary electrodes fabricated in a poly(dimethylsiloxane)-based microfluidic device. Cobalt(II) phthalocyanine-modified carbon paste was used as the working electrode material, allowing selective detection of reduced DTT. The electrochemical sensor was validated off-line against the traditional DTT assay using filter samples taken from urban environments and biomass burning events. After off-line characterization, the sensor was coupled to a PILS to enable on-line sampling/analysis of aerosol oxidative activity. Urban dust and industrial incinerator ash samples were aerosolized in an aerosol chamber and analyzed for their oxidative activity. The on-line sensor reported DTT consumption rates (oxidative activity) in good correlation with aerosol concentration (R(2) from 0.86 to 0.97) with a time resolution of approximately 3 min.

Capillarity-based preparation system for optical colorimetric sensor arrays.

Science.gov (United States)

Luo, Xiao-Gang; Yi, Xin; Bu, Xiang-Nan; Hou, Chang-Jun; Huo, Dan-Qun; Yang, Mei; Fa, Huan-Bao; Lei, Jin-Can

2017-03-01

In recent years, optical colorimetric sensor arrays have demonstrated beneficial features, including rapid response, high selectivity, and high specificity; as a result, it has been extensively applied in food inspection and chemical studies, among other fields. There are instruments in the current market available for the preparation of an optical colorimetric sensor array, but it lacks the corresponding research of the preparation mechanism. Therefore, in connection with the main features of this kind of sensor array such as consistency, based on the preparation method of contact spotting, combined with a capillary fluid model, Washburn equation, Laplace equation, etc., this paper develops a diffusion model of an optical colorimetric sensor array during its preparation and sets up an optical colorimetric sensor array preparation system based on this diffusion model. Finally, this paper compares and evaluates the sensor arrays prepared by the system and prepared manually in three aspects such as the quality of array point, response of array, and response result, and the results show that the performance index of the sensor array prepared by a system under this diffusion model is better than that of the sensor array of manual spotting, which meets the needs of the experiment.

Miniaturized Planar Room Temperature Ionic Liquid Electrochemical Gas Sensor for Rapid Multiple Gas Pollutants Monitoring.

Science.gov (United States)

Wan, Hao; Yin, Heyu; Lin, Lu; Zeng, Xiangqun; Mason, Andrew J

2018-02-01

The growing impact of airborne pollutants and explosive gases on human health and occupational safety has escalated the demand of sensors to monitor hazardous gases. This paper presents a new miniaturized planar electrochemical gas sensor for rapid measurement of multiple gaseous hazards. The gas sensor features a porous polytetrafluoroethylene substrate that enables fast gas diffusion and room temperature ionic liquid as the electrolyte. Metal sputtering was utilized for platinum electrodes fabrication to enhance adhesion between the electrodes and the substrate. Together with carefully selected electrochemical methods, the miniaturized gas sensor is capable of measuring multiple gases including oxygen, methane, ozone and sulfur dioxide that are important to human health and safety. Compared to its manually-assembled Clark-cell predecessor, this sensor provides better sensitivity, linearity and repeatability, as validated for oxygen monitoring. With solid performance, fast response and miniaturized size, this sensor is promising for deployment in wearable devices for real-time point-of-exposure gas pollutant monitoring.

A Molecularly Imprinted Electrochemical Gas Sensor to Sense Butylated Hydroxytoluene in Air

Directory of Open Access Journals (Sweden)

Shadi Emam

2018-01-01

Full Text Available Alzheimer’s disease (AD is a neurodegenerative disease, which affects millions of people worldwide. Curing this disease has not gained much success so far. Exhaled breath gas analysis offers an inexpensive, noninvasive, and immediate method for detecting a large number of diseases, including AD. In this paper, a new method is proposed to detect butylated hydroxytoluene (BHT in the air, which is one of the chemicals found in the breath print of AD patients. A three-layer sensor was formed through deposition of a thin layer of graphene onto a glassy carbon substrate. Selective binding of the analyte was facilitated by electrochemically initiated polymerization of a solution containing the desired target molecule. Subsequent polymerization and removal of the analyte yielded a layer of polypyrrole, a conductive polymer, on top of the sensor containing molecularly imprinted cavities selective for the target molecule. Two sets of sensors have been developed. First, the graphene sensor has been fabricated with a layer of reduced graphene oxide (RGO and tested over 5–100 part per million (ppm. For the second batch, Prussian blue was added to graphene before polymerization, mainly for enhancing the electrochemical properties. The sensor was tested over 0.02-1 parts per billion (ppb level of concentration while the sensor resistance has been monitored.

Preparation and Electrochemical Properties of Silver Doped Hollow Carbon Nanofibers

Directory of Open Access Journals (Sweden)

LI Fu

2016-11-01

Full Text Available Silver doped PAN-based hollow carbon nanofibers were prepared combining co-electrospinning with in situ reduction technique subsequently heat treatment to improve the electrochemical performances of carbon based supercapacitor electrodes. The morphology, structure and electrochemical performances of the resulted nanofiber were studied. The results show that the silver nanoparticles can be doped on the surface of hollow carbon nanofibers and the addition of silver favors the improvement of the electrochemical performances, exhibiting the enhanced reversibility of electrode reaction and the capacitance and the reduced charge transfer impedance.

Integrated electrochemical sensor array for on-line monitoring of yeast fermentations

NARCIS (Netherlands)

Krommenhoek, E.E.; Gardeniers, Johannes G.E.; Bomer, Johan G.; Li, X.; Ottens, M.; van Dedem, G.W.K.; van Leeuwen, M.; van Gulik, W.M.; van der Wielen, L.A.M.; Heijnen, J.J.; van den Berg, Albert

2007-01-01

This paper describes the design, modeling, and experimental characterization of an electrochemical sensor array for on-line monitoring of fermentor conditions in both miniaturized cell assays and in industrial scale fertnentations. The viable biomass concentration is determined from impedance

Molecularly imprinted polymer decorated nanoporous gold for highly selective and sensitive electrochemical sensors

Science.gov (United States)

Li, Yingchun; Liu, Yuan; Liu, Jie; Liu, Jiang; Tang, Hui; Cao, Cong; Zhao, Dongsheng; Ding, Yi

2015-01-01

Electrochemical nanosensors based on nanoporous gold leaf (NPGL) and molecularly imprinted polymer (MIP) are developed for pharmaceutical analysis by using metronidazole (MNZ) as a model analyte. NPGL, serving as the loading platform for MIP immobilization, possesses large accessible surface area with superb electric conductivity, while electrochemically synthesized MIP thin layer affords selectivity for specific recognition of MNZ molecules. For MNZ determination, the hybrid electrode shows two dynamic linear range of 5 × 10-11 to 1 × 10-9 mol L-1 and 1 × 10-9 to 1.4 × 10-6 mol L-1 with a remarkably low detection limit of 1.8 × 10-11 mol L-1 (S/N = 3). In addition, the sensor exhibits high binding affinity and selectivity towards MNZ with excellent reproducibility and stability. Finally, the reliability of MIP-NPGL for MNZ detection is proved in real fish tissue samples, demonstrating the potential for the proposed electrochemical sensors in monitoring drug and biological samples.

Effect of preparation methods on dispersion stability and electrochemical performance of graphene sheets

International Nuclear Information System (INIS)

Chen, Li; Li, Na; Zhang, Mingxia; Li, Pinnan; Lin, Zhengping

2017-01-01

Chemical exfoliation is one of the most important strategies for preparing graphene. The aggregation of graphene sheets severely prevents graphene from exhibiting excellent properties. However, there are no attempts to investigate the effect of preparation methods on the dispersity of graphene sheets. In this study, three chemical exfoliation methods, including Hummers method, modified Hummers method, and improved method, were used to prepare graphene sheets. The influence of preparation methods on the structure, dispersion stability in organic solvents, and electrochemical properties of graphene sheets were investigated. Fourier transform infrared microscopy, Raman spectra, transmission electron microscopy, and UV–vis spectrophotometry were employed to analyze the structure of the as-prepared graphene sheets. The results showed that graphene prepared by improved method exhibits excellent dispersity and stability in organic solvents without any additional stabilizer or modifier, which is attributed to the completely exfoliation and regular structure. Moreover, cyclic voltammetric and electrochemical impedance spectroscopy measurements showed that graphene prepared by improved method exhibits superior electrochemical properties than that prepared by the other two methods. - Graphical abstract: Graphene oxides with different oxidation degree were obtained via three methods, and then graphene with different crystal structures were created by chemical reduction of exfoliated graphene oxides. - Highlights: • Graphene oxides with different oxidation degree were obtained via three oxidation methods. • The influence of oxidation methods on microstructure of graphene was investigated. • The effect of oxidation methods on dispersion stability of graphene was investigated. • The effect of oxidation methods on electrochemical properties of graphene was discussed.

Effect of preparation methods on dispersion stability and electrochemical performance of graphene sheets

Energy Technology Data Exchange (ETDEWEB)

Chen, Li, E-mail: chenli1981@lut.cn; Li, Na; Zhang, Mingxia; Li, Pinnan; Lin, Zhengping

2017-05-15

Chemical exfoliation is one of the most important strategies for preparing graphene. The aggregation of graphene sheets severely prevents graphene from exhibiting excellent properties. However, there are no attempts to investigate the effect of preparation methods on the dispersity of graphene sheets. In this study, three chemical exfoliation methods, including Hummers method, modified Hummers method, and improved method, were used to prepare graphene sheets. The influence of preparation methods on the structure, dispersion stability in organic solvents, and electrochemical properties of graphene sheets were investigated. Fourier transform infrared microscopy, Raman spectra, transmission electron microscopy, and UV–vis spectrophotometry were employed to analyze the structure of the as-prepared graphene sheets. The results showed that graphene prepared by improved method exhibits excellent dispersity and stability in organic solvents without any additional stabilizer or modifier, which is attributed to the completely exfoliation and regular structure. Moreover, cyclic voltammetric and electrochemical impedance spectroscopy measurements showed that graphene prepared by improved method exhibits superior electrochemical properties than that prepared by the other two methods. - Graphical abstract: Graphene oxides with different oxidation degree were obtained via three methods, and then graphene with different crystal structures were created by chemical reduction of exfoliated graphene oxides. - Highlights: • Graphene oxides with different oxidation degree were obtained via three oxidation methods. • The influence of oxidation methods on microstructure of graphene was investigated. • The effect of oxidation methods on dispersion stability of graphene was investigated. • The effect of oxidation methods on electrochemical properties of graphene was discussed.

Mercapto-ordered carbohydrate-derived porous carbon electrode as a novel electrochemical sensor for simple and sensitive ultra-trace detection of omeprazole in biological samples

Energy Technology Data Exchange (ETDEWEB)

Kalate Bojdi, Majid [Department of Chemistry, Faculty of Science, Shahid Beheshti University, Tehran 1983963113 (Iran, Islamic Republic of); Faculty of Chemistry, Kharazmi (Tarbiat Moallem) University, Tehran (Iran, Islamic Republic of); Behbahani, Mohammad [Department of Chemistry, Faculty of Science, Shahid Beheshti University, Tehran 1983963113 (Iran, Islamic Republic of); Mashhadizadeh, Mohammad Hosein [Faculty of Chemistry, Kharazmi (Tarbiat Moallem) University, Tehran (Iran, Islamic Republic of); Bagheri, Akbar [Department of Chemistry, Faculty of Science, Shahid Beheshti University, Tehran 1983963113 (Iran, Islamic Republic of); Hosseiny Davarani, Saied Saeed, E-mail: ss-hosseiny@sbu.ac.ir [Department of Chemistry, Faculty of Science, Shahid Beheshti University, Tehran 1983963113 (Iran, Islamic Republic of); Farahani, Ali [Department of Chemistry, Faculty of Science, Shahid Beheshti University, Tehran 1983963113 (Iran, Islamic Republic of)

2015-03-01

We are introducing mercapto-mesoporous carbon modified carbon paste electrode (mercapto-MP-C-CPE) as a new sensor for trace determination of omeprazole (OM) in biological samples. The synthesized modifier was characterized by thermogravimetry analysis (TGA), differential thermal analysis (DTA), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), elemental analysis (CHN) and N{sub 2} adsorption surface area measurement (BET). The electrochemical response characteristic of the modified-CPE toward OM was investigated by cyclic and differential pulse voltammetry (CV and DPV). The proposed sensor displayed a good electrooxidation response to the OM, its linear range is 0.25 nM to 25 μM with a detection limit of 0.04 nM under the optimized conditions. The prepared modified electrode shows several advantages such as high sensitivity, long-time stability, wide linear range, ease of preparation and regeneration of the electrode surface by simple polishing and excellent reproducibility. - Highlights: • A modified nanoporous carbon as a novel sensor • High stability and good repeatability and reproducibility by the prepared sensor • Trace determination of omeprazole • Biological and pharmaceutical samples.

Mercapto-ordered carbohydrate-derived porous carbon electrode as a novel electrochemical sensor for simple and sensitive ultra-trace detection of omeprazole in biological samples

International Nuclear Information System (INIS)

Kalate Bojdi, Majid; Behbahani, Mohammad; Mashhadizadeh, Mohammad Hosein; Bagheri, Akbar; Hosseiny Davarani, Saied Saeed; Farahani, Ali

2015-01-01

We are introducing mercapto-mesoporous carbon modified carbon paste electrode (mercapto-MP-C-CPE) as a new sensor for trace determination of omeprazole (OM) in biological samples. The synthesized modifier was characterized by thermogravimetry analysis (TGA), differential thermal analysis (DTA), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), elemental analysis (CHN) and N 2 adsorption surface area measurement (BET). The electrochemical response characteristic of the modified-CPE toward OM was investigated by cyclic and differential pulse voltammetry (CV and DPV). The proposed sensor displayed a good electrooxidation response to the OM, its linear range is 0.25 nM to 25 μM with a detection limit of 0.04 nM under the optimized conditions. The prepared modified electrode shows several advantages such as high sensitivity, long-time stability, wide linear range, ease of preparation and regeneration of the electrode surface by simple polishing and excellent reproducibility. - Highlights: • A modified nanoporous carbon as a novel sensor • High stability and good repeatability and reproducibility by the prepared sensor • Trace determination of omeprazole • Biological and pharmaceutical samples

MnO2 prepared by hydrothermal method and electrochemical performance as anode for lithium-ion battery.

Science.gov (United States)

Feng, Lili; Xuan, Zhewen; Zhao, Hongbo; Bai, Yang; Guo, Junming; Su, Chang-Wei; Chen, Xiaokai

2014-01-01

Two α-MnO2 crystals with caddice-clew-like and urchin-like morphologies are prepared by the hydrothermal method, and their structure and electrochemical performance are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), galvanostatic cell cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The morphology of the MnO2 prepared under acidic condition is urchin-like, while the one prepared under neutral condition is caddice-clew-like. The identical crystalline phase of MnO2 crystals is essential to evaluate the relationship between electrochemical performances and morphologies for lithium-ion battery application. In this study, urchin-like α-MnO2 crystals with compact structure have better electrochemical performance due to the higher specific capacity and lower impedance. We find that the relationship between electrochemical performance and morphology is different when MnO2 material used as electrochemical supercapacitor or as anode of lithium-ion battery. For lithium-ion battery application, urchin-like MnO2 material has better electrochemical performance.

Ionic Liquid-Based Optical and Electrochemical Carbon Dioxide Sensors

OpenAIRE

Kamalakanta Behera; Shubha Pandey; Anu Kadyan; Siddharth Pandey

2015-01-01

Due to their unusual physicochemical properties (e.g., high thermal stability, low volatility, high intrinsic conductivity, wide electrochemical windows and good solvating ability), ionic liquids have shown immense application potential in many research areas. Applications of ionic liquid in developing various sensors, especially for the sensing of biomolecules, such as nucleic acids, proteins and enzymes, gas sensing and sensing of various important ions, among other chemosensing platforms, ...

Tunable Signal-Off and Signal-On Electrochemical Cisplatin Sensor.

Science.gov (United States)

Wu, Yao; Lai, Rebecca Y

2017-09-19

We report the first electrochemical cisplatin sensor fabricated with a thiolated and methylene blue (MB)-modified oligo-adenine (A)-guanine (G) DNA probe. Depending on the probe coverage, the sensor can behave as a signal-off or signal-on sensor. For the high-coverage sensor, formation of intrastrand Pt(II)-AG adducts rigidifies the oligo-AG probe, resulting in a concentration-dependent decrease in the MB signal. For the low-coverage sensor, the increase in probe-to-probe spacing enables binding of cisplatin via the intrastrand GNG motif (N = A), generating a bend in the probe which results in an increase in the MB current. Although both high-coverage signal-off and low-coverage signal-on sensors are capable of detecting cisplatin, the signal-on sensing mechanism is better suited for real time analysis of cisplatin. The low-coverage sensor has a lower limit of detection, wider optimal AC frequency range, and faster response time. It has high specificity for cisplatin and potentially other Pt(II) drugs and does not cross-react with satraplatin, a Pt(IV) prodrug. It is also selective enough to be employed directly in 50% saliva and 50% urine. This detection strategy may offer a new approach for sensitive and real time analysis of cisplatin in clinical samples.

Imprinted propyl gallate electrochemical sensor based on graphene/single walled carbon nanotubes/sol-gel film.

Science.gov (United States)

Xu, Guilin; Chi, Yu; Li, Lu; Liu, Shouhua; Kan, Xianwen

2015-06-15

A novel imprinted sol-gel electrochemical sensor for the determination of propyl gallate (PG) was developed based on a composite of graphene and single walled carbon nanotubes (GR-SWCNTs). It was fabricated by stepwise modifying GR-SWCNTs and molecularly imprinted polymers and stored in 0.10 mol L(-1) phosphate buffer solution pH 6.0, which endowed the sensor good sensitivity and selective recognition towards template molecules. The morphology and specific adsorption capacity of the sensor was characterized by scanning electron microscope and electrochemical methods, respectively. Under the optimized conditions, a linear range of the sensor to PG was 8.0 × 10(-8)-2.6 × 10(-3)mo lL(-1) with a limit of detection of 5.0 × 10(-8)mol L(-1) (S/N=3). The sensor exhibited specificity and selectivity towards template molecules as well as excellent reproducibility, regeneration and stability. Furthermore, the sensor could be applied to determine PG in edible oils, instant noodles and cookies with satisfactory results. Copyright © 2015 Elsevier Ltd. All rights reserved.

Investigation of the electrochemical behaviour of thermally prepared ...

African Journals Online (AJOL)

Different IrO2 electrodes in which the molar percentage of platinum (Pt) varies from 0 %mol Pt to 100 %mol Pt were prepared on titanium (Ti) substrate by thermal decomposition techniques. The electrodes were characterized physically (SEM, XPS) and electrochemically and then applied to methanol oxidation. The SEM ...

A highly selective electrochemical sensor based on molecularly imprinted polypyrrole-modified gold electrode for the determination of glyphosate in cucumber and tap water.

Science.gov (United States)

Zhang, Chao; She, Yongxin; Li, Tengfei; Zhao, Fengnian; Jin, Maojun; Guo, Yirong; Zheng, Lufei; Wang, Shanshan; Jin, Fen; Shao, Hua; Liu, Haijin; Wang, Jing

2017-12-01

An electrochemical sensor based on molecularly imprinted polypyrrole (MIPPy) was developed for selective and sensitive detection of the herbicide glyphosate (Gly) in cucumber and tap water samples. The sensor was prepared via synthesis of molecularly imprinted polymers on a gold electrode in the presence of Gly as the template molecule and pyrrole as the functional monomer by cyclic voltammetry (CV). The sensor preparation conditions including the ratio of template to functional monomers, number of CV cycles in the electropolymerization process, the method of template removal, incubation time, and pH were optimized. Under the optimal experimental conditions, the DPV peak currents of hexacyanoferrate/hexacyanoferrite changed linearly with Gly concentration in the range from 5 to 800 ng mL -1 , with a detection limit of 0.27 ng mL -1 (S/N = 3). The sensor was used to detect the concentration of Gly in cucumber and tap water samples, with recoveries ranging from 72.70 to 98.96%. The proposed sensor showed excellent selectivity, good stability and reversibility, and could detect the Gly in real samples rapidly and sensitively. Graphical abstract Schematic illustration of the experimental procedure to detect Gly using the MIPPy electrode.

Real-Time Telemetry System for Amperometric and Potentiometric Electrochemical Sensors

Directory of Open Access Journals (Sweden)

Ching-Hsing Luo

2011-09-01

Full Text Available A real-time telemetry system, which consists of readout circuits, an analog-to-digital converter (ADC, a microcontroller unit (MCU, a graphical user interface (GUI, and a radio frequency (RF transceiver, is proposed for amperometric and potentiometric electrochemical sensors. By integrating the proposed system with the electrochemical sensors, analyte detection can be conveniently performed. The data is displayed in real-time on a GUI and optionally uploaded to a database via the Internet, allowing it to be accessed remotely. An MCU was implemented using a field programmable gate array (FPGA to filter noise, transmit data, and provide control over peripheral devices to reduce power consumption, which in sleep mode is 70 mW lower than in operating mode. The readout circuits, which were implemented in the TSMC 0.18-μm CMOS process, include a potentiostat and an instrumentation amplifier (IA. The measurement results show that the proposed potentiostat has a detectable current range of 1 nA to 100 μA, and linearity with an R2 value of 0.99998 in each measured current range. The proposed IA has a common-mode rejection ratio (CMRR greater than 90 dB. The proposed system was integrated with a potentiometric pH sensor and an amperometric nitrite sensor for in vitro experiments. The proposed system has high linearity (an R2 value greater than 0.99 was obtained in each experiment, a small size of 5.6 cm × 8.7 cm, high portability, and high integration.

A single use electrochemical sensor based on biomimetic nanoceria for the detection of wine antioxidants.

Science.gov (United States)

Andrei, Veronica; Sharpe, Erica; Vasilescu, Alina; Andreescu, Silvana

2016-08-15

We report the development and characterization of a disposable single use electrochemical sensor based on the oxidase-like activity of nanoceria particles for the detection of phenolic antioxidants. The use of nanoceria in the sensor design enables oxidation of phenolic compounds, particularly those with ortho-dihydroxybenzene functionality, to their corresponding quinones at the surface of a screen printed carbon electrode. Detection is carried out by electrochemical reduction of the resulting quinone at a low applied potential of -0.1V vs the Ag/AgCl electrode. The sensor was optimized and characterized with respect to particle loading, applied potential, response time, detection limit, linear concentration range and sensitivity. The method enabled rapid detection of common phenolic antioxidants including caffeic acid, gallic acid and quercetin in the µM concentration range, and demonstrated good functionality for the analysis of antioxidant content in several wine samples. The intrinsic oxidase-like activity of nanoceria shows promise as a robust tool for sensitive and cost effective analysis of antioxidants using electrochemical detection. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrochemical sensor based on magnetic molecularly imprinted nanoparticles modified magnetic electrode for determination of Hb.

Science.gov (United States)

Sun, Binghua; Ni, Xinjiong; Cao, Yuhua; Cao, Guangqun

2017-05-15

A fast and selective electrochemical sensor for determination of hemoglobin (Hb) was developed based on magnetic molecularly imprinted nanoparticles modified on the magnetic glassy carbon electrode. The nanoparticles Fe 3 O 4 @SiO 2 with a magnetic core and a molecularly imprinted shell had regular structures and good monodispersity. Hb could be determined directly by electrochemical oxidization with the modified electrode. A magnetic field increased electrochemical response to Hb by two times. Imprinting Hb on the surface of Fe 3 O 4 @SiO 2 shortened the response time within 7min. Under optimum conditions, the imprinting factor toward the non-imprinted sensor was 2.8, and the separation factor of Hb to horseradish peroxidase was 2.6. The oxidation peak current had a linear relationship with Hb concentration ranged from 0.005mg/ml to 0.1mg/ml with a detection limit (S/N =3) of 0.0010mg/ml. The sensors were successfully applied to analysis of Hb in whole blood samples with recoveries between 95.7% and 105%. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication a new modified electrochemical sensor based on Au–Pd bimetallic nanoparticle decorated graphene for citalopram determination

Energy Technology Data Exchange (ETDEWEB)

Daneshvar, Leili [Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Rounaghi, Gholam Hossein, E-mail: ghrounaghi@yahoo.com [Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Es' haghi, Zarrin [Department of Chemistry, Faculty of Sciences, Payame Noor University, Mashhad (Iran, Islamic Republic of); Chamsaz, Mahmoud; Tarahomi, Somayeh [Department of Chemistry, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

2016-12-01

This paper proposes a simple approach for sensing of citalopram (CTL) using gold–palladium bimetallic nanoparticles (Au–PdNPs) decorated graphene modified gold electrode. Au–PdNPs were deposited at the surface of a graphene modified gold electrode with simple electrodeposition method. The morphology and the electrochemical properties of the modified electrode were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), energy dispersion spectroscopy (EDS), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and square wave voltammetry (SWV). The novel sensor exhibited an excellent catalytic activity towards the oxidation of CTL. The oxidation peak current of CTL, was linear in the range of 0.5–50 μM with a detection limit 0.049 μM with respect to concentration of citalopram. The proposed sensor was successfully applied for determination of CTL tablet and human plasma samples with satisfactory results. - Highlights: • A novel sensor based on Au-PdNPs deposited graphene modified gold electrode was fabricated. • The morphology and the electrochemical properties of the sensor were characterized by several methods. • The fabricated sensor was employed for the detection of antidepressant drug CTL with satisfactory results.

Electrochemical Analysis of Neurotransmitters

Science.gov (United States)

Bucher, Elizabeth S.; Wightman, R. Mark

2015-07-01

Chemical signaling through the release of neurotransmitters into the extracellular space is the primary means of communication between neurons. More than four decades ago, Ralph Adams and his colleagues realized the utility of electrochemical methods for the study of easily oxidizable neurotransmitters, such as dopamine, norepinephrine, and serotonin and their metabolites. Today, electrochemical techniques are frequently coupled to microelectrodes to enable spatially resolved recordings of rapid neurotransmitter dynamics in a variety of biological preparations spanning from single cells to the intact brain of behaving animals. In this review, we provide a basic overview of the principles underlying constant-potential amperometry and fast-scan cyclic voltammetry, the most commonly employed electrochemical techniques, and the general application of these methods to the study of neurotransmission. We thereafter discuss several recent developments in sensor design and experimental methodology that are challenging the current limitations defining the application of electrochemical methods to neurotransmitter measurements.

Fabrication of an electrochemical sensor based on computationally designed molecularly imprinted polymer for the determination of mesalamine in real samples

Energy Technology Data Exchange (ETDEWEB)

Torkashvand, M. [Department of Analytical Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Gholivand, M.B., E-mail: mbgholivand@yahoo.com [Department of Analytical Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Taherkhani, F. [Department of Physical Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of)

2015-10-01

A novel electrochemical sensor based on mesalamine molecularly imprinted polymer (MIP) film on a glassy carbon electrode was fabricated. Density functional theory (DFT) in gas and solution phases was developed to study the intermolecular interactions in the pre-polymerization mixture and to find the suitable functional monomers in MIP preparation. On the basis of computational results, o-phenylenediamine (OP), gallic acid (GA) and p-aminobenzoic acid (ABA) were selected as functional monomers. The MIP film was cast on glassy carbon electrode by electropolymerization of solution containing ternary monomers and then followed by Ag dendrites (AgDs) with nanobranch deposition. The surface feature of the modified electrode (AgDs/MIP/GCE) was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Under the optimal experimental conditions, the peak current was proportional to the concentration of mesalamine ranging from 0.05 to 100 μM, with the detection limit of 0.015 μM. The proposed sensor was applied successfully for mesalamine determination in real samples. - Highlights: • The determination of MES using AgDs/MIP/GCE is reported for the first time. • The computer assisted design of terpolymer MIPs was used to screen monomers. • Theoretical results of DFT approach were in agreement with experimental results. • The sensor displayed a high selectivity for template in the presence of interferes. • The developed sensor has been applied to determine mesalamine in real samples.

Fabrication of an electrochemical sensor based on computationally designed molecularly imprinted polymer for the determination of mesalamine in real samples

International Nuclear Information System (INIS)

Torkashvand, M.; Gholivand, M.B.; Taherkhani, F.

2015-01-01

A novel electrochemical sensor based on mesalamine molecularly imprinted polymer (MIP) film on a glassy carbon electrode was fabricated. Density functional theory (DFT) in gas and solution phases was developed to study the intermolecular interactions in the pre-polymerization mixture and to find the suitable functional monomers in MIP preparation. On the basis of computational results, o-phenylenediamine (OP), gallic acid (GA) and p-aminobenzoic acid (ABA) were selected as functional monomers. The MIP film was cast on glassy carbon electrode by electropolymerization of solution containing ternary monomers and then followed by Ag dendrites (AgDs) with nanobranch deposition. The surface feature of the modified electrode (AgDs/MIP/GCE) was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Under the optimal experimental conditions, the peak current was proportional to the concentration of mesalamine ranging from 0.05 to 100 μM, with the detection limit of 0.015 μM. The proposed sensor was applied successfully for mesalamine determination in real samples. - Highlights: • The determination of MES using AgDs/MIP/GCE is reported for the first time. • The computer assisted design of terpolymer MIPs was used to screen monomers. • Theoretical results of DFT approach were in agreement with experimental results. • The sensor displayed a high selectivity for template in the presence of interferes. • The developed sensor has been applied to determine mesalamine in real samples

Composite of Cu metal nanoparticles-multiwall carbon nanotubes-reduced graphene oxide as a novel and high performance platform of the electrochemical sensor for simultaneous determination of nitrite and nitrate

Energy Technology Data Exchange (ETDEWEB)

Bagheri, Hasan, E-mail: h.bagheri@bmsu.ac.ir [Chemical Injuries Research Center, Baqiyatallah University of Medical Sciences, Tehran (Iran, Islamic Republic of); Hajian, Ali [Laboratory for Sensors, Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges Köhler Allee 103, 79110 Freiburg (Germany); Rezaei, Mosayeb; Shirzadmehr, Ali [Young Researchers and Elite Club, Hamedan Branch, Islamic Azad University, Hamedan (Iran, Islamic Republic of)

2017-02-15

Highlights: • An electrochemical sensor based on Cu metal nanoparticles-multiwall carbon nanotubes-reduced graphene oxide modified glassy carbon electrode was developed. • Simultaneous electrochemical determination of nitrate and nitrite by fabricated sensor was performed. • Modification improved the sensitivity and detection limit of the method. • It is a useful method for determining of nitrate and nitrite in various real samples. - Abstract: In the present research, we aimed to fabricate a novel electrochemical sensor based on Cu metal nanoparticles on the multiwall carbon nanotubes-reduced graphene oxide nanosheets (Cu/MWCNT/RGO) for individual and simultaneous determination of nitrite and nitrate ions. The morphology of the prepared nanocomposite on the surface of glassy carbon electrode (GCE) was characterized using various methods including scanning electron microscopy (SEM), atomic force microscopy (AFM), and electrochemical impedance spectroscopy. Under optimal experimental conditions, the modified GCE showed excellent catalytic activity toward the electro-reduction of nitrite and nitrate ions (pH = 3.0) with a significant increase in cathodic peak currents in comparison with the unmodified GCE. By square wave voltammetry (SWV) the fabricated sensor demonstrated wide dynamic concentration ranges from 0.1 to 75 μM with detection limits (3S{sub b}/m) of 30 nM and 20 nM method for nitrite and nitrate ions, respectively. Furthermore, the applicability of the proposed modified electrode was demonstrated by measuring the concentration of nitrite and nitrate ions in the tap and mineral waters, sausages, salami, and cheese samples.

Composite of Cu metal nanoparticles-multiwall carbon nanotubes-reduced graphene oxide as a novel and high performance platform of the electrochemical sensor for simultaneous determination of nitrite and nitrate

International Nuclear Information System (INIS)

Bagheri, Hasan; Hajian, Ali; Rezaei, Mosayeb; Shirzadmehr, Ali

2017-01-01

Highlights: • An electrochemical sensor based on Cu metal nanoparticles-multiwall carbon nanotubes-reduced graphene oxide modified glassy carbon electrode was developed. • Simultaneous electrochemical determination of nitrate and nitrite by fabricated sensor was performed. • Modification improved the sensitivity and detection limit of the method. • It is a useful method for determining of nitrate and nitrite in various real samples. - Abstract: In the present research, we aimed to fabricate a novel electrochemical sensor based on Cu metal nanoparticles on the multiwall carbon nanotubes-reduced graphene oxide nanosheets (Cu/MWCNT/RGO) for individual and simultaneous determination of nitrite and nitrate ions. The morphology of the prepared nanocomposite on the surface of glassy carbon electrode (GCE) was characterized using various methods including scanning electron microscopy (SEM), atomic force microscopy (AFM), and electrochemical impedance spectroscopy. Under optimal experimental conditions, the modified GCE showed excellent catalytic activity toward the electro-reduction of nitrite and nitrate ions (pH = 3.0) with a significant increase in cathodic peak currents in comparison with the unmodified GCE. By square wave voltammetry (SWV) the fabricated sensor demonstrated wide dynamic concentration ranges from 0.1 to 75 μM with detection limits (3S_b/m) of 30 nM and 20 nM method for nitrite and nitrate ions, respectively. Furthermore, the applicability of the proposed modified electrode was demonstrated by measuring the concentration of nitrite and nitrate ions in the tap and mineral waters, sausages, salami, and cheese samples.

An Electrochemical Sensor Based on Novel Ion Imprinted Polymeric Nanoparticles for Selective Detection of Lead Ions

Directory of Open Access Journals (Sweden)

Masoud Ghanei-Motlagh

1999-11-01

Full Text Available In this study, the novel surface ion-imprinted polymer (IIP particles were prepared and applied as a electrode modifier in stripping voltammetric detection of lead(II ion. A carbon paste electrode (CPE modified with IIP nanoparticles and multi-walled carbon nanotubes (MWCNTs was used for accumulation of toxic lead ions. Various factors that govern on electrochemical signals including carbon paste composition, pH of the preconcentration solution, supporting electrolyte, stirring time, reduction potential and time were studied in detail. The best electrochemical response for Pb(II ions was obtained with a paste composition of 7% (w/w of lead IIP, 10% MWCNTs, 53% (w/w of graphite powder and 30% (w/w of paraffin oil using a solution of 0.1 mol L-1 acetat buffer solution (pH=4.5 with a extraction time of 15 min. A sensitive response for Pb(II ions in the concentration range of 3 to 55 µg L-1 was achived. The proposed electrochemical sensor showed low detection limit (0.5 µg L-1, remarkable selectivity and good reproducibility (RSD = 3.1%. Determination of lead(II content in different environmental water samples was also realized adopting graphite furnace atomic absorptions spectrometry (GF-AAS and the obtained results were satisfactory.

Sensitive detection of pyoverdine with an electrochemical sensor based on electrochemically generated graphene functionalized with gold nanoparticles.

Science.gov (United States)

Gandouzi, Islem; Tertis, Mihaela; Cernat, Andreea; Bakhrouf, Amina; Coros, Maria; Pruneanu, Stela; Cristea, Cecilia

2018-04-01

The design and development of an electrochemical sensor for the sensitive and selective determination of pyoverdine, a virulence factor secreted by Pseudomonas aeruginosa, bacteria involved in nosocomial infections is presented in this work. The presence of pyoverdine in water and body fluids samples can be directly linked to the presence of the Pseudomonas bacteria, thus being a nontoxic and low cost marker for the detection of water pollution as well as for the biological contamination of other media. The sensor was elaborated using layer-by-layer technique for the deposition of a graphene‑gold nanoparticles composite film on the graphite-based screen printed electrode, from aqueous suspension. Under optimal conditions, the electrochemical signal corresponding to the pyoverdine oxidation process was proportional to its concentration, showing a wide linear range from 1 to 100μmolL -1 and a detection limit of 0.33μmolL -1 . This sensor discriminate with satisfactory recoveries the target analyte in different real matrices and also exhibited low response to other interfering species, proving that this technique is promising for medical and environmental applications. In addition, the proposed nanocomposite platform presented good reproducibility, high and long term stability, the sensitivity for pyoverdine remain unchanged after being stored at 4°C for four weeks. Copyright © 2017 Elsevier B.V. All rights reserved.

A novel electrochemical sensor based on zirconia/ordered macroporous polyaniline for ultrasensitive detection of pesticides.

Science.gov (United States)

Wang, Yonglan; Jin, Jun; Yuan, Caixia; Zhang, Fan; Ma, Linlin; Qin, Dongdong; Shan, Duoliang; Lu, Xiaoquan

2015-01-21

A simple and mild strategy was proposed to develop a novel electrochemical sensor based on zirconia/ordered macroporous polyaniline (ZrO2/OMP) and further used for the detection of methyl parathion (MP), one of the organophosphate pesticides (OPPs). Due to the strong affinity of phosphate groups with ZrO2 and the advantages of OMP such as high catalytic activity and good conductivity, the developed sensor showed a limit of detection as low as 2.28 × 10(-10) mol L(-1) (S/N = 3) by square-wave voltammograms, and good selectivity, acceptable reproducibility and stability. Most importantly, this novel sensor was successfully applied to detect MP in real samples of apple and cabbage. It is expected that this method has potential applications in electrochemical sensing platforms with simple, sensitive, selective and fast analysis.

Method of detecting defects in ion exchange membranes of electrochemical cells by chemochromic sensors

Science.gov (United States)

Brooker, Robert Paul; Mohajeri, Nahid

2016-01-05

A method of detecting defects in membranes such as ion exchange membranes of electrochemical cells. The electrochemical cell includes an assembly having an anode side and a cathode side with the ion exchange membrane in between. In a configuration step a chemochromic sensor is placed above the cathode and flow isolation hardware lateral to the ion exchange membrane which prevents a flow of hydrogen (H.sub.2) between the cathode and anode side. The anode side is exposed to a first reactant fluid including hydrogen. The chemochromic sensor is examined after the exposing for a color change. A color change evidences the ion exchange membrane has at least one defect that permits H.sub.2 transmission therethrough.

A micromachined electrochemical sensor for free chlorine monitoring in drinking water.

Science.gov (United States)

Mehta, A; Shekhar, H; Hyun, S H; Hong, S; Cho, H J

2006-01-01

In this work, we designed, fabricated and tested a disposable, flow-through amperometric sensor for free chlorine determination in water. The sensor is based on the principle of an electrochemical cell. The substrate, as well as the top microfluidic layer, is made up of a polymer material. The advantages include; (a) disposability from low cost; (b) stable operation range from three-electrode design; (c) fluidic interconnections that provide on line testing capabilities; and (d) transparent substrate which provides for future integration of on-chip optics. The sensor showed a good response and linearity in the chlorine concentration ranging from 0.3 to 1.6 ppm, which applies to common chlorination process for drinking water purification.

Development and characterization of electrochemical cantilever sensor for bio/chemical sensing applications

DEFF Research Database (Denmark)

Quan, Xueling; Fischer, Lee MacKenzie; Boisen, Anja

2011-01-01

We report the improvements made to our previously developed electrochemical cantilever (EC) sensor, where nanoporous gold material is employed as working electrodes in microcantilever arrays, while combined counter-reference electrodes are integrated on the chip. For a surface stress change of 1m...

Development and Application of Electrochemical Sensor Based on Molecularly Imprinted Polymer and Carbon Nanotubes for the Determination of Carvedilol

Directory of Open Access Journals (Sweden)

Malena Karla Lombello Coelho

2016-11-01

Full Text Available This work describes the preparation of a glassy carbon electrode (GCE modified with molecularly imprinted polymer (MIP and multiwalled carbon nanotubes (MWCNTs for determination of carvedilol (CAR. Electrochemical behavior of CAR on the modified electrode was evaluated using cyclic voltammetry. The best composition was found to be 65% (m/m of MIP. Under optimized conditions (pH 8.5 in 0.25 mol L−1 Britton–Robinson buffer and 0.1 mol L−1 KCl the voltammetric method showed a linear response for CAR in the range of 50–325 µmol L−1 (R = 0.9755, with detection and quantification limits of 16.14 µmol L−1 and 53.8 µmol L−1, respectively. The developed method was successfully applied for determination of CAR in real samples of pharmaceuticals. The sensor presented good sensitivity, rapid detection of CAR, and quick and easy preparation. Furthermore, the material used as modifier has a simple synthesis and its amount utilized is very small, thus illustrating the economic feasibility of this sensor.

Preparation of NiFe₂O₄/graphene nanocomposite and its application as a modifier for the fabrication of an electrochemical sensor for the simultaneous determination of tramadol and acetaminophen

Energy Technology Data Exchange (ETDEWEB)

Afkhami, Abbas, E-mail: afkhami@basu.ac.ir [Faculty of Chemistry, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of); Khoshsafar, Hosein [Faculty of Chemistry, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of); Bagheri, Hasan [Chemical Injuries Research Center, Baqiyatallah University of Medical Sciences, Tehran (Iran, Islamic Republic of); Madrakian, Tayyebeh [Faculty of Chemistry, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of)

2014-06-01

Highlights: • A new modified electrochemical sensor was constructed and used. • NiFe₂O₄/graphene was used as the modifier. • The sensor was used for the determination of tramadol and acetaminophen in real samples. • Modification improved the sensitivity and detection limit of the method. • The oxidation of tramadol and acetaminophen at the surface of the electrode was studied. Abstract: An effective electrochemical sensor for the rapid and simultaneous determination of tramadol and acetaminophen based on carbon paste electrode (CPE) modified with NiFe₂O₄/graphene nanoparticles was developed. The structures of the synthesized NiFe₂O₄/graphene nanocomposite and the electrode composition were confirmed by X-ray diffraction (XRD) spectrometry, Fourier transform infrared (FT-IR) spectrometry and scanning electron microscopy (SEM). The peak currents of square wave voltammetry of tramadol and acetaminophen increased linearly with their concentration in the range of 0.01–9 μmol L⁻¹. The detection limit for their determination was found to be 0.0036 and 0.0030 μmol L⁻¹, respectively. The results show that the combination of graphene and NiFe₂O₄ nanoparticles causes a dramatic enhancement in the sensitivity of the sensor. The fabricated sensor exhibited high sensitivity and good stability, and would be valuable for the clinical assay of tramadol and acetaminophen.

One-step electrodeposition of Au-Pt bimetallic nanoparticles on MoS2 nanoflowers for hydrogen peroxide enzyme-free electrochemical sensor

International Nuclear Information System (INIS)

Zhou, Juan; Zhao, Yanan; Bao, Jing; Huo, Danqun; Fa, Huanbao; Shen, Xin; Hou, Changjun

2017-01-01

The rationally designed sensor architecture is very important to improve the sensitivity and selectivity for H 2 O 2 enzyme-free electrochemical sensor. In this work, a sensitive H 2 O 2 biosensor was fabricated by electrochemical deposition of Au-Pt bimetallic nanoparticles (NPs) on molybdenum disulfide nanoflowers (MoS 2 NFs). Au-Pt NPs was dispersed or stabilized by the effective support matrix of MoS 2 nanosheets, which was effectively enhance the conductivity, catalytic performance and long-term stability. The experimental results show that MoS 2 -Au/Pt nanocomposites exhibit excellent catalytic activity for specific detection of H 2 O 2, and electrochemical measurement results show that the enzyme-free electrochemical sensor has large linear range of 10 μM to 19.07 mM with high sensitivity of 142.68 μA mM −1 cm −2 . This novel sensor produced satisfactory reproducibility and stability, and exhibited superior potential for the practical quantitative analysis of H 2 O 2 in serum samples.

Nonenzymatic electrochemical sensor based on imidazole-functionalized graphene oxide for progesterone detection.

Science.gov (United States)

Gevaerd, Ava; Blaskievicz, Sirlon F; Zarbin, Aldo J G; Orth, Elisa S; Bergamini, Márcio F; Marcolino-Junior, Luiz H

2018-07-30

The modification of electrode surfaces has been the target of study for many researchers in order to improve the analytical performance of electrochemical sensors. Herein, the use of an imidazole-functionalized graphene oxide (GO-IMZ) as an artificial enzymatic active site for voltammetric determination of progesterone (P4) is described for the first time. The morphology and electrochemical performance of electrode modified with GO-IMZ were characterized by scanning electron microscopy and cyclic voltammetry, respectively. Under optimized conditions, the proposed sensor showed a synergistic effect of the GO sheets and the imidazole groups anchored on its backbone, which promoted a significant enhancement on electrochemical reduction of P4. Figures of merits such as linear dynamic response for P4 concentration ranging from 0.22 to 14.0 μmol L -1 , limit of detection of 68 nmol L -1 and limit of quantification and 210 nmol L -1 were found. In addition, presented a higher sensitivity, 426 nA L µmol -1 , when compared to the unmodified electrode. Overall, the proposed device showed to be a promising platform for a simple, rapid, and direct analysis of progesterone. Copyright © 2018 Elsevier B.V. All rights reserved.

Graphene nanoflakes on transparent glass electrode sensor for electrochemical sensing of anti-diabetic drug.

Science.gov (United States)

Narang, Jagriti; Malhotra, Nitesh; Singhal, Chaitali; Bhatia, Rishabh; Kathuria, Vikas; Jain, Manan

2017-04-01

Metformin (Mf) plays a major role in controlling insulin level of individuals at risk of developing diabetes mellitus. Overdose of Mf can cause lactic acidosis, diarrhoea, cough, or hoarseness, etc. These particulars point out the identification for selective and sensitive methods of Mf determination. In the present work, graphene nanoflakes-polymethylene blue (GNF-PMB) nano-composites were developed onto fluorine-doped tin oxide (SnO 2 /F) coated glass substrates for electrochemical sensing of Mf using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The developed sensor shows quick response time (10 s), linearity as 10-10 3  µM, LOD (0.1 nM), and good shelf life (10 weeks). Attempts have been made to utilize this electrode for estimation of Mf in urine samples. Configured as a highly responsive, reproducible Mf sensor, it combines the electrical properties of GNF and stable electron transfer of PMB. The newly developed Mf sensor presents a promising candidate in point-of-care diagnosis.

Electrochemical preparation of technetium hydroxyethylidene diphosphonate radiopharmaceuticals

International Nuclear Information System (INIS)

Scott, R.B.

1984-01-01

This work describes the liquid chromatographic and electrochemical analysis of electrogenerated technetium hydroxyethylidene diphosphonate (HEDP) complexes, and studies the effectiveness of the resulting bone imaging agents. Anion exchange High Performance Liquid Chromatography is used to separate components, and γ emission is used as the detection mode. The reaction mixtures were prepared at a series of reduction potentials and pH values, at both carrier added and no carrier added technetium levels. The results indicate that all three parameters affect the final complex composition to varying degrees. By optimizing the conditions, a preparation was made which results in a high percentage of a Tc-HEDP complex thought to be a very good home imager. This component was isolated chromatographically and injected into female Sprague-Dawley rats. Comparisons were run on the uptake for seven tissue types at two incubation times. Mercury and Reticulated Vitreous Carbon were used as the working electrode materials, and it is shown how reduced technetium will significantly alter the electrode characteristics, where a conditioned electrode will produce different complexes from those produced at fresh electrode material. By employing coulometric analysis as the preparation was reduced, an n value of 4 was calculated for a particular complex. This procedure involved tracking the radioactive technetium species carefully to account for all electrons used in the system. Finally, an electrochemical detection method for HEDP was explored, utilizing the property of mercury complexation. Anodic sweep Differential Pulse Polarography gives an analytical signal for HEDP at +0.250 V vs Ag/AgCl

Hydrogel-based electrochemical sensor for non-invasive and continuous glucose monitoring

Science.gov (United States)

Park, Habeen; Lee, Ji-Young; Kim, Dong-Chul; Koh, Younggook; Cha, Junhoe

2017-07-01

Monitoring blood glucose level of diabetic patients is crucial in diabetes care from life threating complications. Selfmonitoring blood glucose (SMBG) that involves finger prick to draw blood samples into the measurement system is a widely-used method of routine measurement of blood glucose levels to date. SMBG includes, however, unavoidable pain problems resulting from the repetitive measurements. We hereby present a hydrogel-based electrochemical (H-EC) sensor to monitor the glucose level, non-invasively. Glucose oxidase (GOx) was immobilized in the disc-type hydroxyethyl methacrylate (HEMA) based hydrogel and kept intact in the hydrogel. Fast electron transfer mediated by Prussian blue (PB, hexacyanoferrate) generated efficient signal amplifications to facilitate the detection of the extracted glucose from the interstitial fluid. The linear response and the selectivity against glucose of the H-EC sensor were validated by chronoamperometry. For the practical use, the outcomes from the correlation of the extracted glucose concentration and the blood glucose value by on-body extraction, as well as the validation of the hydrogel-based electrochemical (H-EC) device, were applied to the on-body glucose monitoring.

Porous MnO2 prepared by sol-gel method for electrochemical supercapacitor

Science.gov (United States)

Bazzi, K.; Kumar, A.; Jayakumar, O. D.; Nazri, G. A.; Naik, V. M.; Naik, R.

2015-03-01

MnO2 has attracted great attention as material for electrochemical pseudocapacitor due to its high theoretical specific faradic capacitance (~ 1370 F .g-1) , environmental friendliness and wide potential window in both aqueous and nonaqueous electrolytes. However, the MnO2 has a low surface area which depresses its electrochemical performance. The amorphous α-MnO2 composite was synthesized by sol gel method in the presence of the tri-block copolymer P123. Our aim is to investigate the role of P123 on the electrochemical performance of MnO2. The samples with and without P123 were prepared and characterized by x-ray diffraction (XRD), SEM, TEM and Brunauer-Emmett-Teller (BET) method. The electrochemical performances of the amorphous MnO2 composites as the electrode materials for supercapacitors were evaluated by cyclic voltammetry and AC impedance measurements in a 1M Na2SO4 solution. The results show that the sample prepared without P123 exhibited a relatively low specific capacitance of 28F .g-1, whereas the porous MnO2 prepared with P123 exhibited 117 F .g-1at 5 mV/s. The results of crystalline MnO2 composites will also be presented. The authors acknowledge the support from the Richard J. Barber Foundation for Interdisciplinary Research.

An ultrasensitive electrochemical sensor for simultaneous determination of xanthine, hypoxanthine and uric acid based on Co doped CeO{sub 2} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Lavanya, N. [Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi 630003, Tamilnadu (India); Sekar, C., E-mail: Sekar2025@gmail.com [Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi 630003, Tamilnadu (India); Murugan, R.; Ravi, G. [Department of Physics, Alagappa University, Karaikudi 630003, Tamilnadu (India)

2016-08-01

A novel electrochemical sensor has been fabricated using Co doped CeO{sub 2} nanoparticles for selective and simultaneous determination of xanthine (XA), hypoxanthine (HXA) and uric acid (UA) in a phosphate buffer solution (PBS, pH 5.0) for the first time. The Co-CeO{sub 2} NPs have been prepared by microwave irradiation method and characterized by Powder XRD, Raman spectroscopy, HRTEM and VSM measurements. The electrochemical behaviours of XA, HXA and UA at the Co-CeO{sub 2} NPs modified glassy carbon electrode (GCE) were studied by cyclic voltammetry and square wave voltammetry methods. The modified electrode exhibited remarkably well-separated anodic peaks corresponding to the oxidation of XA, HXA and UA over the concentration range of 0.1–1000, 1–600 and 1–2200 μM with detection limits of 0.096, 0.36, and 0.12 μM (S/N = 3), respectively. For simultaneous detection by synchronous change of the concentrations of XA, HXA and UA, the linear responses were in the range of 1–400 μM each with the detection limits of 0.47, 0.26, and 0.43 μM (S/N = 3), respectively. The fabricated sensor was further applied to the detection of XA, HXA and UA in human urine samples with good selectivity and high reproducibility. - Highlights: • A novel electrochemical sensor has been fabricated for simultaneous determination of purine metabolites xanthine, hypoxanthine, and uric acid based on Co doped CeO{sub 2} nanoparticles. • The Co-CeO{sub 2} modified glassy carbon electrode exhibited wide linear range towards the detection of XA, HXA and UA than ever reported in the literature. • The fabricated sensor was successfully applied for the analysis of human urine samples with satisfactory results.

A novel electrochemical sensor for detecting hyperin with a nanocomposite of ZrO2-SDS-SWCNTs as decoration.

Science.gov (United States)

Li, Shuo; Lei, Sheng; Yu, Qian; Zou, Lina; Ye, Baoxian

2018-08-01

A novel high-sensitive electrochemical sensor with glassy carbon electrode (GCE) as support for hyperin determination is successfully designed and constructed, and the well-shaped nano-meter modified material is synthesized via a one-step and facile route. Functionalized with surfactant sodium dodecyl sulfate (SDS), Single-Walled Carbon Nanotubes (SWCNTs) are synchronously grafted with ZrO 2 nanoparticles to develop into the as-prepared nano-composite (ZrO 2 -SDS-SWCNTs). Compared to the previous reports related with hyperin detection, the linear range gets wider and detection limit (LOD) becomes lower with the aid of this novel nano-composite modified glassy carbon electrode (ZrO 2 -SDS-SWCNTs/GCE). The crystalline phases and functionalization of the preparation process has been investigated by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) instrument analysis, respectively, and the micro-morphology of related modified materials is also visibly characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). In addition, electrochemical properties of the modified materials are comparably explored by means of impedance spectroscopy (EIS) and cyclic voltammograms (CV). According to the established calibration curve under optimized condition, the peak current (Differential pulse voltammetry (DPV) signal) keeps a linear relationship with hyperin concentration in the ranges of 1.0 × 10 -9 - 3.0 × 10 -7 mol L -1 , meanwhile detection limit reaches as low as 5 × 10 -10 mol L -1 (S/N = 3). As for practical applications, the proposed sensor has also worked well on sensitive hyperin determination in real species Abelmoschus manihot. Copyright © 2018 Elsevier B.V. All rights reserved.

An electrochemical sensor for indole in plasma based on MWCNTs-chitosan modified screen-printed carbon electrode.

Science.gov (United States)

Jin, Mingchao; Zhang, Xiaoqing; Zhen, Qianna; He, Yifan; Chen, Xiao; Lyu, Wenjing; Han, Runchuan; Ding, Min

2017-12-15

Indole is an essential metabolite in intestinal tract. The dysregulation of plasma indole concentration occurred in various diseases. In this study, the indole in plasma was determined directly using electrochemical sensor with multiwall carbon nanotubes-chitosan (MWCNTs-CS) modified screen-printed carbon electrode (SPCE). The electrochemical behavior of indole was elucidated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) on the MWCNTs-CS composites modified SPCE (MWCNTs-CS/SPCE). The results showed that the current responses of indole improved greatly due to the high catalytic activity and electron transfer reaction of nano-composites. Under the optimized conditions, the linear range of indole was from 5 to 100μgL -1 with the detection limit of 0.5μgL -1 (S/N = 3). This novel electrochemical sensor exhibited acceptable accuracies and precisions with the variations less than 7.3% and 9.0%, respectively. Furthermore, high performance liquid chromatography (HPLC) method was utilized to compare with the established electrochemical method for the determination of indole in plasma. The results showed a high correlation between the two methods. At last, the electrochemical sensor was successfully applied to detect the level of indole in plasma samples with satisfactory selectivity and sensitivity. The concentrations of plasma indole in healthy pregnant women and gestational diabetes mellitus (GDM) patients were 5.3 (4.1-7.0)μgL -1 and 7.2 (4.5-9.4)μgL -1 , respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

Progress in the electrochemical modification of graphene-based materials and their applications

International Nuclear Information System (INIS)

Chakrabarti, M.H.; Low, C.T.J.; Brandon, N.P.; Yufit, V.; Hashim, M.A.; Irfan, M.F.; Akhtar, J.; Ruiz-Trejo, E.; Hussain, M.A.

2013-01-01

Highlights: • Six means of functionalizing graphene electrochemically is reviewed. • Electrochemical functionalization is relatively new to other standard methods. • The technique is expected to improve graphene's application range considerably. -- Abstract: Graphene is a 2D allotrope of carbon with exciting properties such as extremely high electronic conductivity and superior mechanical strength. It has considerable potential for applications in fields such as bio-sensors, electrochemical energy storage and electronics. In most cases, graphene has been functionalized and modified with other materials to prepare composites. This work reviews the electrochemical modification of graphene. Commencing with a brief history, a summary of several different means of modifying graphene to effect diverse applications is provided. This is followed by a discussion on different composite materials that have been prepared with reduced graphene oxide prior to moving onto a detailed consideration of six different methods of electrochemically modifying graphene to prepare composite materials. These methods involve cathodic reduction of graphene oxide, electrophoretic deposition, electro-deposition techniques, electrospinning, electrochemical doping and electrochemical polymerization. Finally a consideration on the applications of electrochemically modified graphene composite materials in various fields is presented prior to discussing some prospects in enhancing the electrochemical process to realize excellent and economic composite materials in bulk

Solid State Electrochemical Sensors for Nitrogen Oxide (NOx) Detection in Lean Exhaust Gases

OpenAIRE

Rheaume, Jonathan Michael

2010-01-01

Solid state electrochemical sensors that measure nitrogen oxides (NOx) in lean exhaust have been investigated in order to help meet future on-board diagnostic (OBD) regulations for diesel vehicles. This impedancemetric detection technology consists of a planar, single cell sensor design with various sensing electrode materials and yttria-stabilized zirconia (YSZ) as the electrolyte. No reference to ambient air is required. An impedance analysis method yields a signal that is proportional to t...

Non-Enzymatic Wearable Sensor for Electrochemical Analysis of Perspiration Glucose.

Science.gov (United States)

Zhu, Xiaofei; Ju, Yinhui; Chen, Jian; Liu, Deye; Liu, Hong

2018-05-16

We report a non-enzymatic wearable sensor for electrochemical analysis of perspiration glucose. Multi-potential steps are applied on a Au electrode, including a high negative pretreatment potential step for proton reduction which produc-es a localized alkaline condition, a moderate potential step for electrocatalytic oxidation of glucose under the alkaline condi-tion, and a positive potential step to clean and reactivate the electrode surface for the next detection. Fluorocarbon-based materials were coated on the Au electrode for improving the selectivity and robustness of the sensor. A fully integrated wrist-band is developed for continuous real-time monitoring of perspiration glucose during physical activities, and uploading the test result to a Smartphone App via Bluetooth.

Synthesis of palladium nanoparticle modified reduced graphene oxide and multi-walled carbon nanotube hybrid structures for electrochemical applications

Energy Technology Data Exchange (ETDEWEB)

Hu, Jie, E-mail: hujie@tyut.edu.cn [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); Zhao, Zhenting; Zhang, Jun; Li, Gang; Li, Pengwei; Zhang, Wendong [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); Lian, Kun, E-mail: liankun@tyut.edu.cn [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); School of Nano-Science and Nano-Engineering, Suzhou & Collaborative Innovation Center of Suzhou Nano Science and Technology, Xi' an Jiaotong University, Xi' an, 710049 (China); Center for Advanced Microstructures and Devices, Louisiana State University, LA, 70806 (United States)

2017-02-28

Graphical abstract: A sensitive hydrazine electrochemical sensor was fabricated by using palladium (Pd) nanoparticle functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotube (MWCNTs) hybrid structures (Pd/rGO-MWCNTs). - Highlights: • rGO-MWCNTs hybrid structures and Pd nanoparticles are prepared using electrochemical methods. • rGO-MWCNTs hybrid films are used as supports and co-catalysts for Pd nanoparticles. • The Pd/rGO-MWCNTs hybrid structure based sensor shows an ultra-high sensitivity of 7.09 μA μM{sup −1} cm{sup −2} and a low detection limit of 0.15 μM. • The proposed electrochemical sensor exhibits excellent selectivity. - Abstract: In this work, palladium (Pd) nanoparticles functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) hybrid structures (Pd/rGO-MWCNTs) were successfully prepared by a combination of electrochemical reduction with electrodeposition method. The morphology, structure, and composition of the Pd/rGO-MWCNTs hybrid were characterized by scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy. The as-synthesized hybrid structures were modified on the glassy carbon electrode (GCE) and further utilized for hydrazine sensing. Electrochemical impedance spectroscopic, cyclic voltammetry and single-potential amperometry experiments were carried out on Pd/rGO-MWCNTs hybrid structures to investigate the interface properties and sensing performance. The measured results demonstrate that the fabricated Pd/rGO-MWCNTs/GCE sensor show a high sensitivity of 7.09 μA μM{sup −1} cm{sup −2} in a large concentration range of 1.0 to 1100 μM and a low detection limit of 0.15 μM. Moreover, the as-prepared sensor exhibits good selectivity and stability for the determination of hydrazine under interference conditions.

Synthesis of palladium nanoparticle modified reduced graphene oxide and multi-walled carbon nanotube hybrid structures for electrochemical applications

International Nuclear Information System (INIS)

Hu, Jie; Zhao, Zhenting; Zhang, Jun; Li, Gang; Li, Pengwei; Zhang, Wendong; Lian, Kun

2017-01-01

Graphical abstract: A sensitive hydrazine electrochemical sensor was fabricated by using palladium (Pd) nanoparticle functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotube (MWCNTs) hybrid structures (Pd/rGO-MWCNTs). - Highlights: • rGO-MWCNTs hybrid structures and Pd nanoparticles are prepared using electrochemical methods. • rGO-MWCNTs hybrid films are used as supports and co-catalysts for Pd nanoparticles. • The Pd/rGO-MWCNTs hybrid structure based sensor shows an ultra-high sensitivity of 7.09 μA μM"−"1 cm"−"2 and a low detection limit of 0.15 μM. • The proposed electrochemical sensor exhibits excellent selectivity. - Abstract: In this work, palladium (Pd) nanoparticles functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) hybrid structures (Pd/rGO-MWCNTs) were successfully prepared by a combination of electrochemical reduction with electrodeposition method. The morphology, structure, and composition of the Pd/rGO-MWCNTs hybrid were characterized by scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy. The as-synthesized hybrid structures were modified on the glassy carbon electrode (GCE) and further utilized for hydrazine sensing. Electrochemical impedance spectroscopic, cyclic voltammetry and single-potential amperometry experiments were carried out on Pd/rGO-MWCNTs hybrid structures to investigate the interface properties and sensing performance. The measured results demonstrate that the fabricated Pd/rGO-MWCNTs/GCE sensor show a high sensitivity of 7.09 μA μM"−"1 cm"−"2 in a large concentration range of 1.0 to 1100 μM and a low detection limit of 0.15 μM. Moreover, the as-prepared sensor exhibits good selectivity and stability for the determination of hydrazine under interference conditions.

Development of self-powered wireless high temperature electrochemical sensor for in situ corrosion monitoring of coal-fired power plant.

Science.gov (United States)

Aung, Naing Naing; Crowe, Edward; Liu, Xingbo

2015-03-01

Reliable wireless high temperature electrochemical sensor technology is needed to provide in situ corrosion information for optimal predictive maintenance to ensure a high level of operational effectiveness under the harsh conditions present in coal-fired power generation systems. This research highlights the effectiveness of our novel high temperature electrochemical sensor for in situ coal ash hot corrosion monitoring in combination with the application of wireless communication and an energy harvesting thermoelectric generator (TEG). This self-powered sensor demonstrates the successful wireless transmission of both corrosion potential and corrosion current signals to a simulated control room environment. Copyright © 2014 ISA. All rights reserved.

Layer-by-Layer films based on biopolymers extracted from red seaweeds and polyaniline for applications in electrochemical sensors of chromium VI

Energy Technology Data Exchange (ETDEWEB)

Oliveira Farias, Emanuel Airton de; Corrêa dos Santos, Marianne; Araujo Dionísio, Natália de; Quelemes, Patrick V.; Souza Almeida Leite, José Roberto de [Núcleo de Pesquisa em Biodiversidade e Biotecnologia, BIOTEC, CMRV, UFPI, Parnaíba, PI 64202-020 (Brazil); Eaton, Peter [UCIBIO, REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, 4169-007 Porto (Portugal); Alves da Silva, Durcilene [Núcleo de Pesquisa em Biodiversidade e Biotecnologia, BIOTEC, CMRV, UFPI, Parnaíba, PI 64202-020 (Brazil); Eiras, Carla, E-mail: eiras@cnpq.br [Núcleo de Pesquisa em Biodiversidade e Biotecnologia, BIOTEC, CMRV, UFPI, Parnaíba, PI 64202-020 (Brazil); Laboratório Interdisciplinar de Materiais Avançados, LIMAV, CCN, UFPI, Teresina, PI 64049-550 (Brazil)

2015-10-15

Graphical abstract: - Highlights: • LbL films based on PANI and polysaccharides of seaweeds were produced and applied sensors of Cr (VI). - Abstract: This paper proposes a new application for natural polysaccharides (agar and carrageenan), both extracted from the cell wall of red seaweeds. Thin films were prepared by the Layer-by-Layer (LbL) self-assembly technique onto ITO (tin-doped indium oxide), where the polysaccharides of interest were deposited in layers alternating with polyaniline (PANI). The films developed were characterized by cyclic voltammetry (CV), ultraviolet–visible spectroscopy (UV–vis) and atomic force microscopy (AFM). Results showed the presence of agar as well as carrageenan, which improves the electrochemical stability of the conducting polymer in an acid medium. The interactions at the molecular level between PANI and the biopolymers affected the most appropriate sequence of deposition as employed in the process of material immobilization and also influenced the resulting morphology. Among the films studied, the most promising system as regards electrochemical measurements was the ITO/agar/PANI system, which was subsequently employed in the electrochemical detection of chromium (VI)

Layer-by-Layer films based on biopolymers extracted from red seaweeds and polyaniline for applications in electrochemical sensors of chromium VI

International Nuclear Information System (INIS)

Oliveira Farias, Emanuel Airton de; Corrêa dos Santos, Marianne; Araujo Dionísio, Natália de; Quelemes, Patrick V.; Souza Almeida Leite, José Roberto de; Eaton, Peter; Alves da Silva, Durcilene; Eiras, Carla

2015-01-01

Graphical abstract: - Highlights: • LbL films based on PANI and polysaccharides of seaweeds were produced and applied sensors of Cr (VI). - Abstract: This paper proposes a new application for natural polysaccharides (agar and carrageenan), both extracted from the cell wall of red seaweeds. Thin films were prepared by the Layer-by-Layer (LbL) self-assembly technique onto ITO (tin-doped indium oxide), where the polysaccharides of interest were deposited in layers alternating with polyaniline (PANI). The films developed were characterized by cyclic voltammetry (CV), ultraviolet–visible spectroscopy (UV–vis) and atomic force microscopy (AFM). Results showed the presence of agar as well as carrageenan, which improves the electrochemical stability of the conducting polymer in an acid medium. The interactions at the molecular level between PANI and the biopolymers affected the most appropriate sequence of deposition as employed in the process of material immobilization and also influenced the resulting morphology. Among the films studied, the most promising system as regards electrochemical measurements was the ITO/agar/PANI system, which was subsequently employed in the electrochemical detection of chromium (VI)

A novel type of electrochemical sensor based on ferromagnetic carbon-encapsulated iron nanoparticles for direct determination of hemoglobin in blood samples.

Science.gov (United States)

Matysiak, Edyta; Donten, Mikolaj; Kowalczyk, Agata; Bystrzejewski, Michal; Grudzinski, Ireneusz P; Nowicka, Anna M

2015-02-15

An effective, fast, facile and direct electrochemical method of determination of hemoglobin (Hb) in blood sample without any sample preparation is described. The method is accomplished by using the ferromagnetic electrode modifier (carbon-encapsulated iron nanoparticles) and an external magnetic field. The successful voltammetric determination of hemoglobin is achieved in PBS buffer as well as in the whole blood sample. The obtained results show the excellent electroactivity of Hb. The measurements are of high sensitivity and good reproducibility. The detection limit is estimated to be 0.7 pM. The electrochemical determination data were compared with the gravimetric data obtained with a quartz crystal microbalance. The agreement between these results is very good. The changes of the electrode surface morphology before and after Hb detection are monitored by electron microscopy. The functionality of the electrochemical sensor is tested with human and rat blood samples. The concentration of hemoglobin in the blood samples determined by using voltammetric/gravimetric detection is in perfect agreement with the data obtained from typical clinical analysis. Copyright © 2014 Elsevier B.V. All rights reserved.

Applications of Ionic Liquids in Electrochemical Sensors and Biosensors

Directory of Open Access Journals (Sweden)

Virendra V. Singh

2012-01-01

Full Text Available Ionic liquids (ILs are salt that exist in the liquid phase at and around 298 K and are comprised of a bulky, asymmetric organic cation and the anion usually inorganic ion but some ILs also with organic anion. ILs have attracted much attention as a replacement for traditional organic solvents as they possess many attractive properties. Among these properties, intrinsic ion conductivity, low volatility, high chemical and thermal stability, low combustibility, and wide electrochemical windows are few. Due to negligible or nonzero volatility of these solvents, they are considered “greener” for the environment as they do not evaporate like volatile organic compounds (VOCs. ILs have been widely used in electrodeposition, electrosynthesis, electrocatalysis, electrochemical capacitor, lubricants, plasticizers, solvent, lithium batteries, solvents to manufacture nanomaterials, extraction, gas absorption agents, and so forth. Besides a brief discussion of the introduction, history, and properties of ILs the major purpose of this review paper is to provide an overview on the advantages of ILs for the synthesis of conducting polymer and nanoparticle when compared to conventional media and also to focus on the electrochemical sensors and biosensors based on IL/composite modified macrodisk electrodes. Subsequently, recent developments and major strategies for enhancing sensing performance are discussed.

Highly sensitive methanol chemical sensor based on undoped silver oxide nanoparticles prepared by a solution method

International Nuclear Information System (INIS)

Rahman, M.M.; Khan, S.B.; Asiri, A.M.; Jamal, A.; Faisal, M.

2012-01-01

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. (author)

Novel Spectroscopic and Electrochemical Sensors and Nanoprobes for the Characterization of Food and Biological Antioxidants.

Science.gov (United States)

Apak, Reşat; Demirci Çekiç, Sema; Üzer, Ayşem; Çelik, Saliha Esin; Bener, Mustafa; Bekdeşer, Burcu; Can, Ziya; Sağlam, Şener; Önem, Ayşe Nur; Erçağ, Erol

2018-01-11

Since an unbalanced excess of reactive oxygen/nitrogen species (ROS/RNS) causes various diseases, determination of antioxidants that can counter oxidative stress is important in food and biological analyses. Optical/electrochemical nanosensors have attracted attention in antioxidant activity (AOA) assessment because of their increased sensitivity and selectivity. Optical sensors offer advantages such as low cost, flexibility, remote control, speed, miniaturization and on-site/in situ analysis. Electrochemical sensors using noble metal nanoparticles on modified electrodes better catalyze bioelectrochemical reactions. We summarize the design principles of colorimetric sensors and nanoprobes for food antioxidants (including electron-transfer based and ROS/RNS scavenging assays) and important milestones contributed by our laboratory. We present novel sensors and nanoprobes together with their mechanisms and analytical performances. Our colorimetric sensors for AOA measurement made use of cupric-neocuproine and ferric-phenanthroline complexes immobilized on a Nafion membrane. We recently designed an optical oxidant/antioxidant sensor using N , N -dimethyl- p -phenylene diamine (DMPD) as probe, from which ROS produced colored DMPD-quinone cationic radicals electrostatically retained on a Nafion membrane. The attenuation of initial color by antioxidants enabled indirect AOA estimation. The surface plasmon resonance absorption of silver nanoparticles as a result of enlargement of citrate-reduced seed particles by antioxidant addition enabled a linear response of AOA. We determined biothiols with Ellman reagent-derivatized gold nanoparticles.

Preparation of the electrochemically formed spinel-lithium manganese oxides

Energy Technology Data Exchange (ETDEWEB)

Katakura, Katsumi; Wada, Kohei; Kajiki, Yoshiyuki; Yamamoto, Akiko [Department of Chemical Engineering, Nara National College of Technology, 22 Yata-cho Yamotokoriyama, Nara 639-1080 (Japan); Ogumi, Zempachi [Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan)

2009-04-01

Electrochemically formed spinel-lithium manganese oxides were synthesized from manganese hydroxides prepared by a cathodic electrochemical precipitation from various concentrations of manganese nitrate solutions. Two types of manganese hydroxides were formed from diluted and concentrated Mn(NO{sub 3}){sub 2} aqueous solutions. Uniform and equi-sized disk shaped Mn(OH){sub 2} crystals of 0.2-5 {mu}m in diameter were obtained on a Pt substrate after the electrochemical precipitation from lower concentration of ranging from 2 mmol dm{sup -3} to 2 mol dm{sup -3} Mn(NO{sub 3}){sub 2} aq., while the grass blade-like precipitate which is ascribed to manganese hydroxide with 20-80 {mu}m long and 1-5 {mu}m wide were formed from concentrated Mn(NO{sub 3}){sub 2} aq. Both manganese hydroxides gave the electrochemically formed spinel-LiMn{sub 2}O{sub 4} onto a Pt sheet, which is ready for electrochemical measurement, after calcination of the Li incorporated precipitate at 750 C without any additives. While the shape and size of the secondary particle frameworks (aggregates) of the electrochemically formed spinel-LiMn{sub 2}O{sub 4} can be controlled by the electrolysis conditions, the nanostructured primary crystals of 200 nm in diameter were obtained in all cases except that the fiber-like nanostructured spinel-LiMn{sub 2}O{sub 4} crystals with 200 nm in diameter were obtained from concentrated Mn(NO{sub 3}){sub 2} aq. Though these two types of electrochemically formed spinel-LiMn{sub 2}O{sub 4} showed well-shaped CVs even in higher scan rates, it would be suitable for high power density battery applications. These behaviors are assumed to be ascribed to the crystal size and shape of the processed spinel-LiMn{sub 2}O{sub 4}. (author)

Field calibration of electrochemical NO2 sensors in a citizen science context

Science.gov (United States)

Mijling, Bas; Jiang, Qijun; de Jonge, Dave; Bocconi, Stefano

2018-03-01

In many urban areas the population is exposed to elevated levels of air pollution. However, real-time air quality is usually only measured at few locations. These measurements provide a general picture of the state of the air, but they are unable to monitor local differences. New low-cost sensor technology is available for several years now, and has the potential to extend official monitoring networks significantly even though the current generation of sensors suffer from various technical issues.Citizen science experiments based on these sensors must be designed carefully to avoid generation of data which is of poor or even useless quality. This study explores the added value of the 2016 Urban AirQ campaign, which focused on measuring nitrogen dioxide (NO2) in Amsterdam, the Netherlands. Sixteen low-cost air quality sensor devices were built and distributed among volunteers living close to roads with high traffic volume for a 2-month measurement period. Each electrochemical sensor was calibrated in-field next to an air monitoring station during an 8-day period, resulting in R2 ranging from 0.3 to 0.7. When temperature and relative humidity are included in a multilinear regression approach, the NO2 accuracy is improved significantly, with R2 ranging from 0.6 to 0.9. Recalibration after the campaign is crucial, as all sensors show a significant signal drift in the 2-month measurement period. The measurement series between the calibration periods can be corrected for after the measurement period by taking a weighted average of the calibration coefficients.Validation against an independent air monitoring station shows good agreement. Using our approach, the standard deviation of a typical sensor device for NO2 measurements was found to be 7 µg m-3, provided that temperatures are below 30 °C. Stronger ozone titration on street sides causes an underestimation of NO2 concentrations, which 75 % of the time is less than 2.3 µg m-3.Our findings show that citizen science

Boronic acid based imprinted electrochemical sensor for rutin recognition and detection.

Science.gov (United States)

Wang, Chunlei; Wang, Qi; Zhong, Min; Kan, Xianwen

2016-10-21

Multi-walled carbon nanotubes (MWNTs) and boronic acid based molecular imprinting polymer (MIP) were successively modified on a glassy carbon electrode surface to fabricate a novel electrochemical sensor for rutin recognition and detection. 3-Aminophenylboronic acid (APBA) was chosen as a monomer for the electropolymerization of MIP film in the presence of rutin. In addition to the imprinted cavities in MIP film to complement the template molecule in shape and functional groups, the high affinity between the boronic acid group of APBA and vicinal diols of rutin also enhanced the selectivity of the sensor, which made the sensor display a good selectivity to rutin. Moreover, the modified MWNTs improved the sensitivity of the sensor for rutin detection. The mole ratios of rutin and APBA, electropolymerized scan cycles and rates, and pH value of the detection solution were optimized. Under optimal conditions, the sensor was used to detect rutin in a linear range from 4.0 × 10 -7 to 1.0 × 10 -5 mol L -1 with a detection limit of 1.1 × 10 -7 mol L -1 . The sensor has also been applied to assay rutin in tablets with satisfactory results.

Electrochemical sensor for ranitidine determination based on carbon paste electrode modified with oxovanadium (IV) salen complex.

Science.gov (United States)

Raymundo-Pereira, Paulo A; Teixeira, Marcos F S; Fatibello-Filho, Orlando; Dockal, Edward R; Bonifácio, Viviane Gomes; Marcolino, Luiz H

2013-10-01

The preparation and electrochemical characterization of a carbon paste electrode modified with the N,N-ethylene-bis(salicyllideneiminato)oxovanadium (IV) complex ([VO(salen)]) as well as its application for ranitidine determination are described. The electrochemical behavior of the modified electrode for the electroreduction of ranitidine was investigated using cyclic voltammetry, and analytical curves were obtained for ranitidine using linear sweep voltammetry (LSV) under optimized conditions. The best voltammetric response was obtained for an electrode composition of 20% (m/m) [VO(salen)] in the paste, 0.10 mol L(-1) of KCl solution (pH 5.5 adjusted with HCl) as supporting electrolyte and scan rate of 25 mV s(-1). A sensitive linear voltammetric response for ranitidine was obtained in the concentration range from 9.9×10(-5) to 1.0×10(-3) mol L(-1), with a detection limit of 6.6×10(-5) mol L(-1) using linear sweep voltammetry. These results demonstrated the viability of this modified electrode as a sensor for determination, quality control and routine analysis of ranitidine in pharmaceutical formulations. Copyright © 2013. Published by Elsevier B.V.

Preparation of NiFe2O4/graphene nanocomposite and its application as a modifier for the fabrication of an electrochemical sensor for the simultaneous determination of tramadol and acetaminophen

International Nuclear Information System (INIS)

Afkhami, Abbas; Khoshsafar, Hosein; Bagheri, Hasan; Madrakian, Tayyebeh

2014-01-01

Highlights: • A new modified electrochemical sensor was constructed and used. • NiFe 2 O 4 /graphene was used as the modifier. • The sensor was used for the determination of tramadol and acetaminophen in real samples. • Modification improved the sensitivity and detection limit of the method. • The oxidation of tramadol and acetaminophen at the surface of the electrode was studied. - Abstract: An effective electrochemical sensor for the rapid and simultaneous determination of tramadol and acetaminophen based on carbon paste electrode (CPE) modified with NiFe 2 O 4 /graphene nanoparticles was developed. The structures of the synthesized NiFe 2 O 4 /graphene nanocomposite and the electrode composition were confirmed by X-ray diffraction (XRD) spectrometry, Fourier transform infrared (FT-IR) spectrometry and scanning electron microscopy (SEM). The peak currents of square wave voltammetry of tramadol and acetaminophen increased linearly with their concentration in the range of 0.01–9 μmol L −1 . The detection limit for their determination was found to be 0.0036 and 0.0030 μmol L −1 , respectively. The results show that the combination of graphene and NiFe 2 O 4 nanoparticles causes a dramatic enhancement in the sensitivity of the sensor. The fabricated sensor exhibited high sensitivity and good stability, and would be valuable for the clinical assay of tramadol and acetaminophen

Evaluation of low-cost electro-chemical sensors for environmental monitoring of ozone, nitrogen dioxide, and carbon monoxide.

Science.gov (United States)

Afshar-Mohajer, Nima; Zuidema, Christopher; Sousan, Sinan; Hallett, Laura; Tatum, Marcus; Rule, Ana M; Thomas, Geb; Peters, Thomas M; Koehler, Kirsten

2018-02-01

Development of an air quality monitoring network with high spatio-temporal resolution requires installation of a large number of air pollutant monitors. However, state-of-the-art monitors are costly and may not be compatible with wireless data logging systems. In this study, low-cost electro-chemical sensors manufactured by Alphasense Ltd. for detection of CO and oxidative gases (predominantly O 3 and NO 2 ) were evaluated. The voltages from three oxidative gas sensors and three CO sensors were recorded every 2.5 sec when exposed to controlled gas concentrations in a 0.125-m 3 acrylic glass chamber. Electro-chemical sensors for detection of oxidative gases demonstrated sensitivity to both NO 2 and O 3 with similar voltages recorded when exposed to equivalent environmental concentrations of NO 2 or O 3 gases, when evaluated separately. There was a strong linear relationship between the recorded voltages and target concentrations of oxidative gases (R 2 > 0.98) over a wide range of concentrations. Although a strong linear relationship was also observed for CO concentrations below 12 ppm, a saturation effect was observed wherein the voltage only changes minimally for higher CO concentrations (12-50 ppm). The nonlinear behavior of the CO sensors implied their unsuitability for environments where high CO concentrations are expected. Using a manufacturer-supplied shroud, sensors were tested at 2 different flow rates (0.25 and 0.5 Lpm) to mimic field calibration of the sensors with zero air and a span gas concentration (2 ppm NO2 or 15 ppm CO). As with all electrochemical sensors, the tested devices were subject to drift with a bias up to 20% after 9 months of continuous operation. Alphasense CO sensors were found to be a proper choice for occupational and environmental CO monitoring with maximum concentration of 12 ppm, especially due to the field-ready calibration capability. Alphasense oxidative gas sensors are usable only if it is valuable to know the sum of

Ordered mesoporous carbon for electrochemical sensing: A review

Energy Technology Data Exchange (ETDEWEB)

Ndamanisha, Jean Chrysostome [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China); Universite du Burundi, Institut de pedagogie appliquee, B.P. 5223, Bujumbura (Burundi); Guo Liping, E-mail: guolp078@nenu.edu.cn [Faculty of Chemistry, Northeast Normal University, Changchun 130024 (China)

2012-10-17

Highlights: Black-Right-Pointing-Pointer The preparation and functionalization of ordered mesoporous carbon. Black-Right-Pointing-Pointer Their applications as electrochemical sensors with high electrocatalytic activity. Black-Right-Pointing-Pointer A promising electrode material based on its interesting properties. - Abstract: With its well-ordered pore structure, high specific surface area and tunable pore diameters in the mesopore range, ordered mesoporous carbon (OMC) is suitable for applications in catalysis and sensing. We report recent applications of OMC in electrochemical sensors and biosensors. After a brief description of the electrochemical properties, the functionalization of the OMC for improvement of the electrocatalytic properties is then presented. We show how the ordered mesostructure of OMC is very important in those applications. The high density of edge plane-like defective sites (EDSs), oxygen-containing groups and a large surface area on OMC may provide many favorable sites for electron transfer to compounds, which makes OMC a potential novel material for an investigation of the electrochemical behavior of substances. Moreover, the structural capabilities of OMC at the scale of a few nanometers agree with immobilization of other electrocataytic substances. Interesting properties of this material may open up a new approach to study the electrochemical determination of other biomolecules.

para-Sulfonatocalix[6]arene-modified silver nanoparticles electrodeposited on glassy carbon electrode: preparation and electrochemical sensing of methyl parathion.

Science.gov (United States)

Bian, Yinghui; Li, Chunya; Li, Haibing

2010-05-15

In this paper, a new electrochemical sensor, based on modified silver nanoparticles, was fabricated using one-step electrodeposition approach. The para-sulfonatocalix[6]arene-modified silver nanoparticles coated on glassy carbon electrode (pSC(6)-Ag NPs/GCE) was characterized by attenuated total reflection IR spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), etc. The pSC(6) as the host are highly efficient to capture organophosphates (OPs), which dramatically facilitates the enrichment of nitroaromatic OPs onto the electrochemical sensor surface. The combination of the host-guest supramolecular structure and the excellent electrochemical catalytic activities of the pSC(6)-Ag NPs/GCE provides a fast, simple, and sensitive electrochemical method for detecting nitroaromatic OPs. In this work, methyl parathion (MP) was used as a nitroaromatic OP model for testing the proposed sensor. In comparison with Ag NPs-modified electrode, the cathodic peak current of MP was amplified significantly. Differential pulse voltammetry was used for the simultaneous determination of MP. Under optimum conditions, the current increased linearly with the increasing concentration of MP in the range of 0.01-80microM, with a detection limit of 4.0nM (S/N=3). The fabrication reproducibility and stability of the sensor is better than that of enzyme-based electrodes. The possible underlying mechanism is discussed.

Operating modes of electrochemical H-concentration probes for tritium sensors

International Nuclear Information System (INIS)

Juhera, E.; Colominas, S.; Abellà, J.

2015-01-01

Highlights: • Synthesis and chemical characterization of Sr(Ce_0_._9–Zr_0_._1)_0_._9_5Yb_0_._0_5O_3_−_α proton conductor ceramic. • Evaluation of the sensor performance at different hydrogen concentrations. • Two different operating modes of the sensors: amperometric and potentiometric. • In amperometric mode sensor sensitivity can be tuned by changing the applied voltage. - Abstract: Potentiometric hydrogen sensors using different solid-state electrolytes have been designed and tested at the Electrochemical Methods Lab at Institut Quimic de Sarria (IQS). The most promising element (Sr(Ce_0_._9–Zr_0_._1)_0_._9_5Yb_0_._0_5O_3_−_α) has been selected for this work in order to evaluate the sensor performance at different hydrogen concentrations in two different operating modes: amperometric and potentiometric. In addition, the sensor response has been evaluated at different working temperatures (500, 575 and 650 °C). The experiments performed proved that when the sensor was used in a potentiometric mode, there is a threshold hydrogen concentration that the sensor can detect depending on the working conditions; 15 mbar at 575 °C and 10 mbar 650 °C. At 500 °C the minimum working temperature of this ceramic has not been achieved, so large deviations between experimental data and theoretical calculations has been obtained. When the sensor was used in an amperometric mode the obtained currents increased as a function of the applied voltage. At a fixed potential, the higher the temperature the higher the current was. So the sensor sensitivity can be tuned by changing the applied voltage at a fixed temperature and hydrogen concentration.

Electrochemical synthesis of mesoporous Pt-Au binary alloys with tunable compositions for enhancement of electrochemical performance.

Science.gov (United States)

Yamauchi, Yusuke; Tonegawa, Akihisa; Komatsu, Masaki; Wang, Hongjing; Wang, Liang; Nemoto, Yoshihiro; Suzuki, Norihiro; Kuroda, Kazuyuki

2012-03-21

Mesoporous Pt-Au binary alloys were electrochemically synthesized from lyotropic liquid crystals (LLCs) containing corresponding metal species. Two-dimensional exagonally ordered LLC templates were prepared on conductive substrates from diluted surfactant solutions including water, a nonionic surfactant, ethanol, and metal species by drop-coating. Electrochemical synthesis using such LLC templates enabled the preparation of ordered mesoporous Pt-Au binary alloys without phase segregation. The framework composition in the mesoporous Pt-Au alloy was controlled simply by changing the compositional ratios in the precursor solution. Mesoporous Pt-Au alloys with low Au content exhibited well-ordered 2D hexagonal mesostructures, reflecting those of the original templates. With increasing Au content, however, the mesostructural order gradually decreased, thereby reducing the electrochemically active surface area. Wide-angle X-ray diffraction profiles, X-ray photoelectron spectra, and elemental mapping showed that both Pt and Au were atomically distributed in the frameworks. The electrochemical stability of mesoporous Pt-Au alloys toward methanol oxidation was highly improved relative to that of nonporous Pt and mesoporous Pt films, suggesting that mesoporous Pt-Au alloy films are potentially applicable as electrocatalysts for direct methanol fuel cells. Also, mesoporous Pt-Au alloy electrodes showed a highly sensitive amperometric response for glucose molecules, which will be useful in next-generation enzyme-free glucose sensors.

Calibration and assessment of electrochemical air quality sensors by co-location with regulatory-grade instruments

Science.gov (United States)

Hagan, David H.; Isaacman-VanWertz, Gabriel; Franklin, Jonathan P.; Wallace, Lisa M. M.; Kocar, Benjamin D.; Heald, Colette L.; Kroll, Jesse H.

2018-01-01

The use of low-cost air quality sensors for air pollution research has outpaced our understanding of their capabilities and limitations under real-world conditions, and there is thus a critical need for understanding and optimizing the performance of such sensors in the field. Here we describe the deployment, calibration, and evaluation of electrochemical sensors on the island of Hawai`i, which is an ideal test bed for characterizing such sensors due to its large and variable sulfur dioxide (SO2) levels and lack of other co-pollutants. Nine custom-built SO2 sensors were co-located with two Hawaii Department of Health Air Quality stations over the course of 5 months, enabling comparison of sensor output with regulatory-grade instruments under a range of realistic environmental conditions. Calibration using a nonparametric algorithm (k nearest neighbors) was found to have excellent performance (RMSE 0.997) across a wide dynamic range in SO2 ( 2 ppm). However, since nonparametric algorithms generally cannot extrapolate to conditions beyond those outside the training set, we introduce a new hybrid linear-nonparametric algorithm, enabling accurate measurements even when pollutant levels are higher than encountered during calibration. We find no significant change in instrument sensitivity toward SO2 after 18 weeks and demonstrate that calibration accuracy remains high when a sensor is calibrated at one location and then moved to another. The performance of electrochemical SO2 sensors is also strong at lower SO2 mixing ratios (pollutant species in other areas (e.g., polluted urban regions), the calibration and validation approaches described here should be widely applicable to a range of pollutants, sensors, and environments.

Preparing the key metabolite of Z-ligustilide in vivo by a specific electrochemical reaction.

Science.gov (United States)

Duan, Feipeng; Xu, Wenjuan; Liu, Jie; Jia, Zhixin; Chen, Kuikui; Chen, Yijun; Wang, Mingxia; Ma, Kaiyue; Dong, Jiaojiao; Chen, Lianming; Xiao, Hongbin

2018-04-16

The key in vivo metabolites of a drug play an important role in its efficacy and toxicity. However, due to the low content and instability of these metabolites, they are hard to obtain through in vivo methods. Electrochemical reactions can be an efficient alternative to biotransformation in vivo for the preparation of metabolites. Accordingly, in this study, the metabolism of Z-ligustilide was investigated in vitro by electrochemistry coupled online to mass spectrometry. This work showed that five oxidation products of the electrochemical reaction were detected and that two of the oxidation products (senkyunolide I and senkyunolide H) were identified from liver microsomal incubation as well. Furthermore, after intragastric administration of Z-ligustilide in rats, senkyunolide I and senkyunolide H were detected in the rat plasma and liver, while 6,7-epoxyligustilide, a key intermediate metabolite of Z-ligustilide, was difficult to detect in vivo. By contrast, 6,7-epoxyligustilide was obtained from the electrochemical reaction. In addition, for the first time, 6 mg of 6,7-epoxyligustilide was prepared from 120 mg of Z-ligustilide. Therefore, electrochemical reactions represent an efficient laboratory method for preparing key drug metabolites. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An ultrasensitive and selective electrochemical sensor for determination of estrone 3-sulfate sodium salt based on molecularly imprinted polymer modified carbon paste electrode.

Science.gov (United States)

Song, Han; Wang, Yuli; Zhang, Lu; Tian, Liping; Luo, Jun; Zhao, Na; Han, Yajie; Zhao, Feilang; Ying, Xue; Li, Yingchun

2017-11-01

A highly sensitive and selective electrochemical sensor based on carbon paste electrode (CPE) modified with molecularly imprinted polymers (MIPs) has been developed for the determination of estrone 3-sulfate sodium salt (ESS). MIPs were prepared in polar medium via bulk polymerization and characterized by scanning electron microscopy and infrared spectroscopy. Cyclic voltammetry was performed to the study preparation process and binding behavior of the MIP-modified CPE (MIP/CPE) toward ESS. The conditions for preparing MIPs and MIP/CPE as well as ESS detection were optimized. Under the optimal experimental conditions, the detection linear range for ESS is 4 × 10 -12 to 6 × 10 -9  M with a limit of detection of 1.18 × 10 -12  M (S/N = 3). In addition, the sensor exhibits high binding affinity toward ESS over its structural analogues with excellent repeatability and stability. The fabricated MIP/CPE was then successfully employed to detect ESS in pregnant mare urine (PMU) without any pretreatment, and the average recoveries were from 99.6 to 104.9% with relative standard deviation less than 3.0%. High-performance liquid chromatography was adopted as a reference to validate the established approach in detecting ESS and their results showed good agreement. The as-prepared sensor has high potential to be a decent tool for on-site determination of ESS in PMU in a fast and convenient manner. Graphical Abstract ᅟ.

Preparation and characterization of a new carbonaceous material for electrochemical systems

Directory of Open Access Journals (Sweden)

ZI JI LIN

2010-02-01

Full Text Available A new carbonaceous material was successfully prepared by the py-rolysis of scrap tire rubber at 600 °C under a nitrogen atmosphere. The physical characteristics of the prepared carbonaceous material were studied by scanning electron microscopy (SEM, X-ray powder diffraction (XRD and X-ray photoelectron spectroscopy (XPS. It was proved that the carbonaceous material had a disordered structure and spherical morphology with an average particle size about 100 nm. The prepared carbonaceous material was also used as electrodes in electrochemical systems to examine its electrochemical performances. It was demonstrated that it delivered a lithium insertion capacity of 658 mA h g-1 during the first cycle with a coulombic efficiency of 68 %. Cyclic voltammograms test results showed that a redox reaction occurred during the cycles. The chemical diffusion coefficient based on the impedance diagram was about 10-10 cm2 s-1. The pyrolytic carbonaceous material derived from scrap tire rubber is therefore considered to be a potential anode material in lithium secondary batteries or capacitors. Furthermore, it is advantageous for environmental protection.

A highly sensitive electrochemical sensor for the determination of methanol based on PdNPs@SBA-15-PrEn modified electrode.

Science.gov (United States)

Karimi, Ziba; Shamsipur, Mojtaba; Tabrizi, Mahmoud Amouzadeh; Rostamnia, Sadegh

2018-05-01

In this study, a novel electrochemical sensor for the determination of methanol based on palladium nanoparticles supported on Santa barbara amorphous-15- PrNHEtNH 2 (PdNPs@SBA-15-PrEn) as nanocatalysis platform is presented. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and electrochemical methods are employed to characterize the PdNPs@SBA-15-PrEn nanocomposite. The Nafion-Pd@SBA-15-PrEn modified glassy carbon electrode (Nafion-PdNPs@SBA-15-PrEn/GCE) displayed the high electrochemical activity and excellent catalytic characteristic for electro-oxidation of methanol in an alkaline solution. The electro-oxidation performance of the proposed sensor was investigated using cyclic voltammetry (CV) and amperometry. The sensor exhibits a good sensitivity of 0.0905 Amol -1 Lcm -2 , linear range of 20-1000 μM and the corresponding detection limit of 12 μM (3σ). The results demonstrate that the Nafion-PdNPs@SBA-15-PrEn/GCE has potential as an efficient and integrated sensor for methanol detection. Copyright © 2018 Elsevier Inc. All rights reserved.

Portable Analyzer Based on Microfluidics/Nanoengineered Electrochemical Sensors for In-situ Characterization of Mixed Wastes

Energy Technology Data Exchange (ETDEWEB)

Yuehe Lin; Glen E. Fryxell; Wassana Yantasee; Guodong Liu; Zheming Wang

2006-06-01

Required characterizations of the DOE's transuranic (TRU) and mixed wastes (MW) before disposing and treatment of the wastes are currently costly and have lengthy turnaround. Research toward developing faster and more sensitive characterization and analysis tools to reduce costs and accelerate throughputs is therefore desirable. This project is aimed at the development of electrochemical sensors, specific to toxic transition metals, uranium, and technetium, that can be integrated into the portable sensor systems. This system development will include fabrication and performance evaluation of electrodes as well as understanding of electrochemically active sites on the electrodes specifically designed for toxic metals, uranium and technetium detection. Subsequently, these advanced measurement units will be incorporated into a microfluidic prototype specifically designed and fabricated for field-deployable characterizations of such species.

Mercapto-ordered carbohydrate-derived porous carbon electrode as a novel electrochemical sensor for simple and sensitive ultra-trace detection of omeprazole in biological samples.

Science.gov (United States)

Kalate Bojdi, Majid; Behbahani, Mohammad; Mashhadizadeh, Mohammad Hosein; Bagheri, Akbar; Hosseiny Davarani, Saied Saeed; Farahani, Ali

2015-03-01

We are introducing mercapto-mesoporous carbon modified carbon paste electrode (mercapto-MP-C-CPE) as a new sensor for trace determination of omeprazole (OM) in biological samples. The synthesized modifier was characterized by thermogravimetry analysis (TGA), differential thermal analysis (DTA), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), elemental analysis (CHN) and N2 adsorption surface area measurement (BET). The electrochemical response characteristic of the modified-CPE toward OM was investigated by cyclic and differential pulse voltammetry (CV and DPV). The proposed sensor displayed a good electrooxidation response to the OM, its linear range is 0.25nM to 25μM with a detection limit of 0.04nM under the optimized conditions. The prepared modified electrode shows several advantages such as high sensitivity, long-time stability, wide linear range, ease of preparation and regeneration of the electrode surface by simple polishing and excellent reproducibility. Copyright © 2014 Elsevier B.V. All rights reserved.

An electrochemical methanol sensor based on a Pd-Ni/SiNWs catalytic electrode

International Nuclear Information System (INIS)

Tao Bairui; Zhang Jian; Hui Shichao; Chen Xuejiao; Wan Lijuan

2010-01-01

A novel electrochemical methanol sensor based on a catalytic electrode of palladium-nickel/silicon nanowires (Pd-Ni/SiNWs) is presented in this paper. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electrochemical methods are employed to investigate the Pd-Ni/SiNWs electrode materials. These nanocomposite materials exhibit a highly ordered, wire-like structure with a wire length of ∼50 μm and a wire diameter ranging from 100 to 300 nm. The substrate has good electrocatalytic activity towards the oxidation of methanol in alkaline solutions. The performances of the prototype sensor are characterized by cyclic voltammetry and fixed potential amperometry techniques. In a 1 mol L -1 KOH solution containing different methanol concentrations, the sensor exhibits a good sensitivity of 1.96 mA mmol -1 L cm -2 with R 2 = 0.99 and the corresponding detection limit of 18 μmol L -1 (signal-to-noise ratio = 3, S/N = 3) for cyclic voltammetry. Meanwhile, the electrode also displays a sensitivity of 0.48 mA mmol -1 L cm -2 with R 2 = 0.98 and the corresponding detection limit of 25 μmol L -1 (S/N = 3) for a fixed potential amperometry at -0.3 V versus an Ag/AgCl reference electrode. The results demonstrate that the Pd-Ni/SiNWs catalytic electrode has potential as an efficient and integrated sensor for methanol detection.

Development of Self-Powered Wireless-Ready High Temperature Electrochemical Sensors for In-Situ Corrosion Monitoring for Boiler Tubes in Next Generation Coal-based Power Systems

Energy Technology Data Exchange (ETDEWEB)

Liu, Xingbo [West Virginia Univ., Morgantown, WV (United States)

2015-06-30

The key innovation of this project is the synergy of the high temperature sensor technology based on the science of electrochemical measurement and state-of-the-art wireless communication technology. A novel self-powered wireless high temperature electrochemical sensor system has been developed for coal-fired boilers used for power generation. An initial prototype of the in-situ sensor demonstrated the capability of the wireless communication system in the laboratory and in a pilot plant (Industrial USC Boiler Setting) environment to acquire electrochemical potential and current signals during the corrosion process. Uniform and localized under-coal ash deposit corrosion behavior of Inconel 740 superalloy has been studied at different simulated coal ash hot corrosion environments using the developed sensor. Two typical potential noise patterns were found to correlate with the oxidation and sulfidation stages in the hot coal ash corrosion process. Two characteristic current noise patterns indicate the extent of the corrosion. There was a good correlation between the responses of electrochemical test data and the results from corroded surface analysis. Wireless electrochemical potential and current noise signals from a simulated coal ash hot corrosion process were concurrently transmitted and recorded. The results from the performance evaluation of the sensor confirm a high accuracy in the thermodynamic and kinetic response represented by the electrochemical noise and impedance test data.

Characterization of carbon nanotubes decorated with NiFe2O4 magnetic nanoparticles as a novel electrochemical sensor: Application for highly selective determination of sotalol using voltammetry

International Nuclear Information System (INIS)

Ensafi, Ali A.; Allafchian, Ali R.; Rezaei, B.; Mohammadzadeh, R.

2013-01-01

A magnetic nano‐composite of multiwall carbon nanotube, decorated with NiFe 2 O 4 nanoparticles, was synthesized with citrate sol–gel method. The multiwall carbon nanotubes decorated with NiFe 2 O 4 nanoparticles (NiFe 2 O 4 –MWCNTs) were characterized with different methods such as Fourier transform infrared spectroscopy (FT‐IR), transmission electron microscopy (TEM), atomic force microscopy (AFM), vibrating sample magnetometer (VSM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The new nano-composite acts as a suitable electrocatalyst for the oxidation of sotalol at a potential of 500 mV at the surface of the modified electrode. Linear sweep voltammetry exhibited two wide linear dynamic ranges of 0.5–1000 μmol L −1 sotalol with a detection limit of 0.09 μmol L −1 . The modified electrode was used as a novel electrochemical sensor for the determination of sotalol in real samples such as pharmaceutical, patient and safe human urine. - Graphical abstract: Multiwall carbon nanotube, decorated with NiFe 2 O 4 nanoparticles, was prepared using citrate sol–gel method. We characterized the new nanoparticles with different spectroscopic and voltammetric methods. The nano sensor was used as a voltammetric sensor for the determination of trace amounts of sotalol at pH 7.0. Highlights: ► We synthesized and prepared new sensor, multiwall carbon nanotubes decorated with NiFe 2 O 4 . ► Several spectroscopic and voltammetric methods were used to study its characteristics. ► The nanoparticles act as suitable electrocatalyst for the oxidation of sotalol. ► Sotalol could be measured as low as 0.09 μmol L −1 using linear sweep voltammetry.

Electrochemical sensors and devices for heavy metals assay in water: the French groups' contribution

Directory of Open Access Journals (Sweden)

Luca ePUJOL

2014-04-01

Full Text Available A great challenge in the area of heavy metal trace detection is the development of electrochemical techniques and devices which are user-friendly, robust, selective, with low detection limits and allowing fast analyses. This review presents the major contribution of the French scientific academic community in the field of electrochemical sensors and electroanalytical methods within the last 20 years. From the well-known polarography to the up-to-date generation of functionalized interfaces, the different strategies dedicated to analytical performances improvement are exposed: stripping voltammetry, solid mercury-free electrode, ion selective sensor, carbon based materials, chemically modified electrodes, nano-structured surfaces. The paper particularly emphasizes their advantages and limits face to the last Water Frame Directive devoted to the Environmental Quality Standards for heavy metals. Recent trends on trace metal speciation as well as on automatic on line monitoring devices are also evoked.

Electrochemical sensors applied to pollution monitoring: Measurement error and gas ratio bias - A volcano plume case study

Science.gov (United States)

Roberts, T. J.; Saffell, J. R.; Oppenheimer, C.; Lurton, T.

2014-06-01

There is an increasing scientific interest in the use of miniature electrochemical sensors to detect and quantify atmospheric trace gases. This has led to the development of ‘Multi-Gas' systems applied to measurements of both volcanic gas emissions, and urban air pollution. However, such measurements are subject to uncertainties introduced by sensor response time, a critical issue that has received limited attention to date. Here, a detailed analysis of output from an electrochemical SO2 sensor and two H2S sensors (contrasting in their time responses and cross-sensitivities) demonstrates how instrument errors arise under the conditions of rapidly fluctuating (by dilution) gas abundances, leading to scatter and importantly bias in the reported gas ratios. In a case study at Miyakejima volcano (Japan), electrochemical sensors were deployed at both the crater-rim and downwind locations, thereby exposed to rapidly fluctuating and smoothly varying plume gas concentrations, respectively. Discrepancies in the H2S/SO2 gas mixing ratios derived from these measurements are attributed to the sensors' differing time responses to SO2 and H2S under fluctuating plume conditions, with errors magnified by the need to correct for SO2 interference in the H2S readings. Development of a sensor response model that reproduces sensor t90 behaviour (the time required to reach 90% of the final signal following a step change in gas abundance) during calibration enabled this measurement error to be simulated numerically. The sensor response times were characterised as SO2 sensor (t90 ~ 13 s), H2S sensor without interference (t90 ~ 11 s), and H2S sensor with interference (t90 ~ 20 s to H2S and ~ 32 s to SO2). We show that a method involving data integration between periods of episodic plume exposure identifiable in the sensor output yields a less biased H2S/SO2 ratio estimate than that derived from standard analysis approaches. For the Miyakejima crater-rim dataset this method yields highly

Electrochemical study of oxidation process of promethazine using sensor based on carbon nanotubes paste containing immobilized DNA on inorganic matrix

Directory of Open Access Journals (Sweden)

João Paulo Marco

2014-10-01

Full Text Available In the present work the voltammetric behavior and the oxidation process of promethazine (PHZ in electrochemical sensor based on carbon nanotubes paste containing DNA immobilized on the inorganic matrix prepared by sol-gel process (SiO2/Al2O3/Nb2O5. The method of Laviron verified that the system is irreversible and high speed of electron transfer between the electrode and DNA. The study of the oxidation of PHZ and influence of pH showed slope of 0.054 V / pH (near the nernstian system: 0.0592 V / pH suggesting that it involves the transfer of two protons and two electrons.

Electroactive Properties of 1-propyl-3-methylimidazolium Ionic Liquid Covalently Bonded on Mesoporous Silica Surface: Development of an Electrochemical Sensor Probed for NADH, Dopamine and Uric Acid Detection

International Nuclear Information System (INIS)

Maroneze, Camila M.; Rahim, Abdur; Fattori, Natália; Costa, Luiz P. da; Sigoli, Fernando A.; Mazali, Italo O.; Custodio, Rogério; Gushikem, Yoshitaka

2014-01-01

Graphical abstract: - Abstract: A hybrid organic-inorganic porous material was successfully prepared through chemical modification of a non-ordered mesoporous silica, obtained by the sol-gel process, with 1-propyl-3-methylimidazolium groups. The porous material was evaluated as a platform for the development of electrochemical sensors, here probed toward the electrooxidation of NADH (β-nicotinamide adenine dinucleotide), uric acid (UA) and dopamine (DA). The presence of cationic imidazolium groups on the surface of the hybrid silica-based material allowed the electrochemical detection of these biomolecules without any other electron mediator or biomolecular recognition component. Such behavior highlights the potentiality of this material to be applied in the development of new electrochemical sensing devices. Theoretical calculations based on density functional theory emphasizes that the cationic character of imidazolium group provides better oxidation conditions if the solvent effect is minimized

Recent advances in synthesis of three-dimensional porous graphene and its applications in construction of electrochemical (bio)sensors for small biomolecules detection.

Science.gov (United States)

Lu, Lu

2018-07-01

Electrochemical (bio)sensors have attracted much attention due to their high sensitivity, fast response time, biocompatibility, low cost and easy miniaturization. Specially, ever-growing necessity and interest have given rise to the fast development of electrochemical (bio)sensors for the detection of small biomolecules. They play enormous roles in the life processes with various biological function, such as life signal transmission, genetic expression and metabolism. Moreover, their amount in body can be used as an indicator for diagnosis of many diseases. For example, an abnormal concentration of blood glucose can indicate hyperglycemia or hypoglycemia. Graphene (GR) shows great applications in electrochemical (bio)sensors. Compared with two-dimensional (2D) GR that is inclined to stack together due to the strong π-π interaction, monolithic 3D porous GR has larger specific area, superior mechanical strength, better stability, higher conductivity and electrocatalytic activity. So they attracted more and increasing attention as sensing materials for small biomolecules. This review focuses on the recent advances and strategies in the fabrication methods of 3D porous GR and the development of various electrochemical (bio)sensors based on porous GR and its nanocomposites for the detection of small biomolecules. The challenges and future efforts direction of high-performance electrochemical (bio)sensors based on 3D porous GR for more sensitive analysis of small biomolecules are discussed and proposed. It will give readers an overall understanding of their progress and provide some theoretical guidelines for their future efforts and development. Copyright © 2018 Elsevier B.V. All rights reserved.

Cold pressure welding of aluminium-steel blanks: Manufacturing process and electrochemical surface preparation

Science.gov (United States)

Schmidt, Hans Christian; Homberg, Werner; Orive, Alejandro Gonzalez; Grundmeier, Guido; Hordych, Illia; Maier, Hans Jürgen

2018-05-01

In this study the manufacture of aluminium-steel blanks by cold pressure welding and their preparation for a welding process through electrochemical surface treatment are investigated and discussed. The cold pressure welding process was done with an incremental rolling tool that allows for the partial pressure welding of two blanks along a prepared path. The influence of the surface preparation by electrochemical deposition of bond promoting organosilane-based agents and roughening on a nano-scale is investigated and compared to conventional surface treatments. Coating the surfaces with a thin organosilane-based film incorporating specific functional groups should promote additional bonding between the mating oxide layers; its influence on the total weld strength is studied. Pressure welding requires suitable process strategies, and the current advances in the proposed incremental rolling process for the combination of mild steel and aluminium are presented.

Mechanochemical preparation of polydiphenylamine and its electrochemical performance in hybrid supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Palaniappan, SP. [Department of Industrial Chemistry, School of Chemistry, Alagappa University, Alagappapuram, Karaikudi 630003, Tamil Nadu (India); Manisankar, P., E-mail: pms11@rediffmail.com [Department of Industrial Chemistry, School of Chemistry, Alagappa University, Alagappapuram, Karaikudi 630003, Tamil Nadu (India)

2011-07-01

Highlights: > For the first time, a simple to adopt, greener, rapid and efficient alternative route was successfully developed for preparing different PDPA salts. > For the first time, a judicial attempt was made to evaluate the performance of mechanochemically prepared PDPA-H{sub 2}SO{sub 4} as cathode material in asymmetric hybrid supercapacitors. > The results obtained are highly promising and the physicochemical properties of PDPA salts could be fine-tuned in the future for large scale applications in energy storage devices. - Abstract: A simple mechanochemical route for the synthesis of high quality inorganic anion doped polydiphenylamines (PDPAs) is reported in this article. Elemental analysis performed for the PDPAs indicated the presence of dopant anions in the polymeric chain. PDPA prepared in the presence of 96 wt% H{sub 2}SO{sub 4} (PDPA-H{sub 2}SO{sub 4}) was found to be better doped than the other polymeric salts. Spectroscopic profiles of the polymers showed that the PDPAs were in a doped conducting state. The X-ray diffraction (XRD) pattern of the as-prepared polymeric powders revealed the presence of more crystalline phases in PDPA-H{sub 2}SO{sub 4}. Field emission scanning electron microscopic (FESEM) images highlighted the formation of inorganic anion doped PDPA particles with different sizes (80-100 nm). Electrochemical studies performed for the polymeric particles depicted the redox behavior and good electrochemical activity of PDPA salts. Thermogravimetric analysis (TGA)/differential thermal analysis (DTA) proved that all the PDPA salts were thermally stable up to 300 deg. C. The electrochemical performance of PDPA-H{sub 2}SO{sub 4} in hybrid supercapacitors was evaluated due to its superior physicochemical properties. The maximum specific capacitance of the hybrid supercapacitor constructed out of PDPA-H{sub 2}SO{sub 4} powder was found to be 108 F g{sup -1}.

A Printed Organic Circuit System for Wearable Amperometric Electrochemical Sensors.

Science.gov (United States)

Shiwaku, Rei; Matsui, Hiroyuki; Nagamine, Kuniaki; Uematsu, Mayu; Mano, Taisei; Maruyama, Yuki; Nomura, Ayako; Tsuchiya, Kazuhiko; Hayasaka, Kazuma; Takeda, Yasunori; Fukuda, Takashi; Kumaki, Daisuke; Tokito, Shizuo

2018-04-23

Wearable sensor device technologies, which enable continuous monitoring of biological information from the human body, are promising in the fields of sports, healthcare, and medical applications. Further thinness, light weight, flexibility and low-cost are significant requirements for making the devices attachable onto human tissues or clothes like a patch. Here we demonstrate a flexible and printed circuit system consisting of an enzyme-based amperometric sensor, feedback control and amplification circuits based on organic thin-film transistors. The feedback control and amplification circuits based on pseudo-CMOS inverters were successfuly integrated by printing methods on a plastic film. This simple system worked very well like a potentiostat for electrochemical measurements, and enabled the quantitative and real-time measurement of lactate concentration with high sensitivity of 1 V/mM and a short response time of a hundred seconds.

Electrochemical sensor for catechol and dopamine based on a catalytic molecularly imprinted polymer-conducting polymer hybrid recognition element.

Science.gov (United States)

Lakshmi, Dhana; Bossi, Alessandra; Whitcombe, Michael J; Chianella, Iva; Fowler, Steven A; Subrahmanyam, Sreenath; Piletska, Elena V; Piletsky, Sergey A

2009-05-01

One of the difficulties with using molecularly imprinted polymers (MIPs) and other electrically insulating materials as the recognition element in electrochemical sensors is the lack of a direct path for the conduction of electrons from the active sites to the electrode. We have sought to address this problem through the preparation and characterization of novel hybrid materials combining a catalytic MIP, capable of oxidizing the template, catechol, with an electrically conducting polymer. In this way a network of "molecular wires" assists in the conduction of electrons from the active sites within the MIP to the electrode surface. This was made possible by the design of a new monomer that combines orthogonal polymerizable functionality; comprising an aniline group and a methacrylamide. Conducting films were prepared on the surface of electrodes (Au on glass) by electropolymerization of the aniline moiety. A layer of MIP was photochemically grafted over the polyaniline, via N,N'-diethyldithiocarbamic acid benzyl ester (iniferter) activation of the methacrylamide groups. Detection of catechol by the hybrid-MIP sensor was found to be specific, and catechol oxidation was detected by cyclic voltammetry at the optimized operating conditions: potential range -0.6 V to +0.8 V (vs Ag/AgCl), scan rate 50 mV/s, PBS pH 7.4. The calibration curve for catechol was found to be linear to 144 microM, with a limit of detection of 228 nM. Catechol and dopamine were detected by the sensor, whereas analogues and potentially interfering compounds, including phenol, resorcinol, hydroquinone, serotonin, and ascorbic acid, had minimal effect (< or = 3%) on the detection of either analyte. Non-imprinted hybrid electrodes and bare gold electrodes failed to give any response to catechol at concentrations below 0.5 mM. Finally, the catalytic properties of the sensor were characterized by chronoamperometry and were found to be consistent with Michaelis-Menten kinetics.

A Nanocoaxial-Based Electrochemical Sensor for the Detection of Cholera Toxin

Science.gov (United States)

Archibald, Michelle; Rizal, Binod; Connolly, Timothy; Burns, Michael J.; Naughton, Michael J.; Chiles, Thomas C.; Biology; Physics Collaboration

We report a nanocoax-based electrochemical sensor for the detection of bacterial toxins using an electrochemical enzyme-linked immunosorbent assay (ELISA) and differential pulse voltammetry (DPV). The device architecture is composed of vertically-oriented, nanoscale coaxial electrodes, with coax cores and shields serving as integrated working and counter electrodes, respectively. Proof-of-concept was demonstrated for the detection of cholera toxin (CT), with a linear dynamic range of detection was 10 ng/ml - 1 µg/ml, and a limit of detection (LOD) of 2 ng/ml. This level of sensitivity is comparable to the standard optical ELISA used widely in clinical applications. The nanocoax array thus matches the detection profile of the standard ELISA while providing a simple electrochemical readout and a miniaturized platform with multiplexing capabilities, toward point-of-care (POC) implementation. In addition, next generation nanocoax devices with extended cores are currently under development, which would provide a POC platform amenable for biofunctionalization of ELISA receptor proteins directly onto the device. This work was supported by the National Institutes of Health (National Cancer Institute Award No. CA137681 and National Institute of Allergy and Infectious Diseases Award No. AI100216).

Electrochemical Impedance Sensors for Monitoring Trace Amounts of NO3 in Selected Growing Media.

Science.gov (United States)

Ghaffari, Seyed Alireza; Caron, William-O; Loubier, Mathilde; Normandeau, Charles-O; Viens, Jeff; Lamhamedi, Mohammed S; Gosselin, Benoit; Messaddeq, Younes

2015-07-21

With the advent of smart cities and big data, precision agriculture allows the feeding of sensor data into online databases for continuous crop monitoring, production optimization, and data storage. This paper describes a low-cost, compact, and scalable nitrate sensor based on electrochemical impedance spectroscopy for monitoring trace amounts of NO3- in selected growing media. The nitrate sensor can be integrated to conventional microelectronics to perform online nitrate sensing continuously over a wide concentration range from 0.1 ppm to 100 ppm, with a response time of about 1 min, and feed data into a database for storage and analysis. The paper describes the structural design, the Nyquist impedance response, the measurement sensitivity and accuracy, and the field testing of the nitrate sensor performed within tree nursery settings under ISO/IEC 17025 certifications.

Poly(vinyl Alcohol) Borate Gel Polymer Electrolytes Prepared by Electrodeposition and Their Application in Electrochemical Supercapacitors.

Science.gov (United States)

Jiang, Mengjin; Zhu, Jiadeng; Chen, Chen; Lu, Yao; Ge, Yeqian; Zhang, Xiangwu

2016-02-10

Gel polymer electrolytes (GPEs) have been studied for preparing flexible and compact electrochemical energy storage devices. However, the preparation and use of GPEs are complex, and most GPEs prepared through traditional methods do not have good wettability with the electrodes, which retard them from achieving their performance potential. In this study, these problems are addressed by conceiving and implementing a simple, but effective, method of electrodepositing poly(vinyl alcohol) potassium borate (PVAPB) GPEs directly onto the surfaces of active carbon electrodes for electrochemical supercapacitors. PVAPB GPEs serve as both the electrolyte and the separator in the assembled supercapacitors, and their scale and shape are determined solely by the geometry of the electrodes. PVAPB GPEs have good bonding to the active electrode materials, leading to excellent and stable electrochemical performance of the supercapacitors. The electrochemical performance of PVAPB GPEs and supercapacitors can be manipulated simply by adjusting the concentration of KCl salt used during the electrodeposition process. With a 0.9 M KCl concentration, the as-prepared supercapacitors deliver a specific capacitance of 65.9 F g(-1) at a current density of 0.1 A g(-1) and retain more than 95% capacitance after 2000 charge/discharge cycles at a current density of 1 A g(-1). These supercapacitors also exhibit intelligent high voltage self-protection function due to the electrolysis-induced cross-linking effect of PVAPB GPEs.

A new electrochemical sensor for the simultaneous determination of acetaminophen and codeine based on porous silicon/palladium nanostructure.

Science.gov (United States)

Ensafi, Ali A; Ahmadi, Najmeh; Rezaei, Behzad; Abarghoui, Mehdi Mokhtari

2015-03-01

A porous silicon/palladium nanostructure was prepared and used as a new electrode material for the simultaneous determination of acetaminophen (ACT) and codeine (COD). Palladium nanoparticles were assembled on porous silicon (PSi) microparticles by a simple redox reaction between the Pd precursor and PSi in an aqueous solution of hydrofluoric acid. This novel nanostructure was characterized by different spectroscopic and electrochemical techniques including scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, fourier transform infrared spectroscopy and cyclic voltammetry. The high electrochemical activity, fast electron transfer rate, high surface area and good antifouling properties of this nanostructure enhanced the oxidation peak currents and reduced the peak potentials of ACT and COD at the surface of the proposed sensor. Simultaneous determination of ACT and COD was explored using differential pulse voltammetry. A linear range of 1.0-700.0 µmol L(-1) was achieved for ACT and COD with detection limits of 0.4 and 0.3 µmol L(-1), respectively. Finally, the proposed method was used for the determination of ACT and COD in blood serum, urine and pharmaceutical compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

Electrochemical Preparation of Polyaniline Nanowires with the Used Electrolyte Solution Treated with the Extraction Process and Their Electrochemical Performance

Directory of Open Access Journals (Sweden)

Ying Wu

2018-02-01

Full Text Available Electrochemical polymerization of aniline is one of the most promising methods to prepare polyaniline (PANI materials. However, during this process, the electrolyte solution must be replaced after electropolymerization of a certain time because of the generation and the accumulation of the by-products, which have significant effects on the morphology, purity and properties of PANI products. Treatment and recycling of the used electrolyte solution are worthwhile to study to reduce the high treatment cost of the used electrolyte solution containing aniline and its polymerization by-products. Here, the composition of the used electrolyte solution was separated and determined by high performance liquid chromatography coupled with diode array detection (HPLC-DAD in the range of ultraviolet and visible (UV-Vis light. The analysis results revealed that the used electrolyte solution consisted of aniline, p-hydroquinone (HQ, p-benzoquinone (BQ, co-oligomers of aniline and p-benzoquinone (CAB and acid. Then, n-octanol and 2-octanone were selected as extracts to remove HQ, BQ and CAB from the used electrolyte solution. Following that, the recycled electrolyte solution was prepared by adjusting the concentration of aniline and acid of the aqueous phase, and the electrochemical polymerization process was conducted. Finally, the obtained PANI was characterized by scanning electron microscope (SEM and electrochemical methods. The experimental results clearly demonstrate that the morphology and specific capacitance of PANI produced from the recycled electrolyte solution can be recovered completely. This research paves the way for reusing the used electrolyte solution for aniline electrochemical polymerization.

Electrochemical Preparation of Polyaniline Nanowires with the Used Electrolyte Solution Treated with the Extraction Process and Their Electrochemical Performance.

Science.gov (United States)

Wu, Ying; Wang, Jixiao; Ou, Bin; Zhao, Song; Wang, Zhi; Wang, Shichang

2018-02-12

Electrochemical polymerization of aniline is one of the most promising methods to prepare polyaniline (PANI) materials. However, during this process, the electrolyte solution must be replaced after electropolymerization of a certain time because of the generation and the accumulation of the by-products, which have significant effects on the morphology, purity and properties of PANI products. Treatment and recycling of the used electrolyte solution are worthwhile to study to reduce the high treatment cost of the used electrolyte solution containing aniline and its polymerization by-products. Here, the composition of the used electrolyte solution was separated and determined by high performance liquid chromatography coupled with diode array detection (HPLC-DAD) in the range of ultraviolet and visible (UV-Vis) light. The analysis results revealed that the used electrolyte solution consisted of aniline, p-hydroquinone (HQ), p-benzoquinone (BQ), co-oligomers of aniline and p-benzoquinone (CAB) and acid. Then, n-octanol and 2-octanone were selected as extracts to remove HQ, BQ and CAB from the used electrolyte solution. Following that, the recycled electrolyte solution was prepared by adjusting the concentration of aniline and acid of the aqueous phase, and the electrochemical polymerization process was conducted. Finally, the obtained PANI was characterized by scanning electron microscope (SEM) and electrochemical methods. The experimental results clearly demonstrate that the morphology and specific capacitance of PANI produced from the recycled electrolyte solution can be recovered completely. This research paves the way for reusing the used electrolyte solution for aniline electrochemical polymerization.

Highly Selective Polypyrrole MIP-Based Gravimetric and Electrochemical Sensors for Picomolar Detection of Glyphosate

Directory of Open Access Journals (Sweden)

Zouhour Mazouz

2017-11-01

Full Text Available There is a global debate and concern about the use of glyphosate (Gly as an herbicide. New toxicological studies will determine its use in the future under new strict conditions or its replacement by alternative synthetic or natural herbicides. In this context, we designed biomimetic polymer sensing layers for the selective molecular recognition of Gly. Towards this end, complementary surface acoustic wave (SAW and electrochemical sensors were functionalized with polypyrrole (PPy-imprinted polymer for the selective detection of Gly. Their corresponding limits of detection were on the order of 1 pM, which are among the lowest values ever reported in literature. The relevant dissociation constants between PPy and Gly were estimated at [Kd1 = (0.7 ± 0.3 pM and Kd2 = (1.6 ± 1.4 µM] and [Kd1 = (2.4 ± 0.9 pM and Kd2 = (0.3 ± 0.1 µM] for electrochemical and gravimetric measurements, respectively. Quantum chemical calculations permitted to estimate the interaction energy between Gly and PPy film: ΔE = −145 kJ/mol. Selectivity and competitivity tests were investigated with the most common pesticides. This work conclusively shows that gravimetric and electrochemical results indicate that both MIP-based sensors are perfectly able to detect and distinguish glyphosate without any ambiguity.

Electrochemical performance of multi-element doped α-nickel hydroxide prepared by supersonic co-precipitation method

International Nuclear Information System (INIS)

Zhang, Z.J.; Zhu, Y.J.; Bao, J.; Lin, X.R.; Zheng, H.Z.

2011-01-01

Highlights: → The α-nickel hydroxides doped with several elements were prepared by supersonic co-precipitation method. → Cyclic voltammetry and electrochemical impedance spectroscopy show sample C has the best electrochemical performance. → The charge/discharge tests show that the 0.5 C discharge capacity (346 mAh/g) of sample C is even larger than that (337 mAh/g) at 0.1 C rate, while the discharge capacity at 0.5 C rate is much lower than that at 0.1 C rate for samples A and B. - Abstract: The multi-element doped α-nickel hydroxides have been prepared by supersonic co-precipitation method. Three kinds of samples A, B, C were prepared by chemically coprecipitating Ni, Al, Co, Y, Zn. It was found that sample C produced better performance than the others. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements indicated that sample C has better electrochemical performance, such as better reaction reversibility, higher proton diffusion coefficient and lower charge-transfer resistance, than those of samples A and B. The charge-discharge tests showed that the discharge capacity (346 mA h/g) of sample C is even larger at 0.5 C rate than that (337mAh/g) at 0.1 C rate, while the discharge capacity at 0.5 C rate is much lower than that at 0.1 C rate for samples A and B. It indicates that all doped elements can produce the synergic effect and further improve the electrochemical properties of the active materials.

Biological and chemical sensors based on graphene materials.

Science.gov (United States)

Liu, Yuxin; Dong, Xiaochen; Chen, Peng

2012-03-21

Owing to their extraordinary electrical, chemical, optical, mechanical and structural properties, graphene and its derivatives have stimulated exploding interests in their sensor applications ever since the first isolation of free-standing graphene sheets in year 2004. This article critically and comprehensively reviews the emerging graphene-based electrochemical sensors, electronic sensors, optical sensors, and nanopore sensors for biological or chemical detection. We emphasize on the underlying detection (or signal transduction) mechanisms, the unique roles and advantages of the used graphene materials. Properties and preparations of different graphene materials, their functionalizations are also comparatively discussed in view of sensor development. Finally, the perspective and current challenges of graphene sensors are outlined (312 references).

Computer-assisted electrochemical fabrication of a highly selective and sensitive amperometric nitrite sensor based on surface decoration of electrochemically reduced graphene oxide nanosheets with CoNi bimetallic alloy nanoparticles.

Science.gov (United States)

Gholivand, Mohammad-Bagher; Jalalvand, Ali R; Goicoechea, Hector C

2014-07-01

For the first time, a novel, robust and very attractive statistical experimental design (ED) using minimum-run equireplicated resolution IV factorial design (Min-Run Res IV FD) coupled with face centered central composite design (FCCCD) and Derringer's desirability function (DF) was developed to fabricate a highly selective and sensitive amperometric nitrite sensor based on electrodeposition of CoNi bimetallic alloy nanoparticles (NPs) on electrochemically reduced graphene oxide (ERGO) nanosheets. The modifications were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), energy dispersive X-ray spectroscopic (EDS), scanning electron microscopy (SEM) techniques. The CoNi bimetallic alloy NPs were characterized using digital image processing (DIP) for particle counting (density estimation) and average diameter measurement. Under the identified optimal conditions, the novel sensor detects nitrite in concentration ranges of 0.1-30.0 μM and 30.0-330.0 μM with a limit of detection (LOD) of 0.05 μM. This sensor selectively detects nitrite even in the presence of high concentration of common ions and biological interferents therefore, we found that the sensor is highly selective. The sensor also demonstrated an excellent operational stability and good antifouling properties. The proposed sensor was used to the determination of nitrite in several foodstuff and water samples. Copyright © 2014. Published by Elsevier B.V.

Fabrication of a Microneedle/CNT Hierarchical Micro/Nano Surface Electrochemical Sensor and Its In-Vitro Glucose Sensing Characterization

Directory of Open Access Journals (Sweden)

Youngsam Yoon

2013-12-01

Full Text Available We report fabrication of a microneedle-based three-electrode integrated electrochemical sensor and in-vitro characterization of this sensor for glucose sensing applications. A piece of silicon was sequentially dry and wet etched to form a 15 × 15 array of tall (approximately 380 µm sharp silicon microneedles. Iron catalyst was deposited through a SU-8 shadow mask to form the working electrode and counter electrode. A multi-walled carbon nanotube forest was grown directly on the silicon microneedle array and platinum nano-particles were electrodeposited. Silver was deposited on the Si microneedle array through another shadow mask and chlorinated to form a Ag/AgCl reference electrode. The 3-electrode electrochemical sensor was tested for various glucose concentrations in the range of 3~20 mM in 0.01 M phosphate buffered saline (PBS solution. The sensor’s amperometric response to the glucose concentration is linear and its sensitivity was found to be 17.73 ± 3 μA/mM-cm2. This microneedle-based sensor has a potential to be used for painless diabetes testing applications.

Calibration and assessment of electrochemical air quality sensors by co-location with regulatory-grade instruments

Directory of Open Access Journals (Sweden)

D. H. Hagan

2018-01-01

Full Text Available The use of low-cost air quality sensors for air pollution research has outpaced our understanding of their capabilities and limitations under real-world conditions, and there is thus a critical need for understanding and optimizing the performance of such sensors in the field. Here we describe the deployment, calibration, and evaluation of electrochemical sensors on the island of Hawai`i, which is an ideal test bed for characterizing such sensors due to its large and variable sulfur dioxide (SO2 levels and lack of other co-pollutants. Nine custom-built SO2 sensors were co-located with two Hawaii Department of Health Air Quality stations over the course of 5 months, enabling comparison of sensor output with regulatory-grade instruments under a range of realistic environmental conditions. Calibration using a nonparametric algorithm (k nearest neighbors was found to have excellent performance (RMSE < 7 ppb, MAE < 4 ppb, r2 > 0.997 across a wide dynamic range in SO2 (< 1 ppb, > 2 ppm. However, since nonparametric algorithms generally cannot extrapolate to conditions beyond those outside the training set, we introduce a new hybrid linear–nonparametric algorithm, enabling accurate measurements even when pollutant levels are higher than encountered during calibration. We find no significant change in instrument sensitivity toward SO2 after 18 weeks and demonstrate that calibration accuracy remains high when a sensor is calibrated at one location and then moved to another. The performance of electrochemical SO2 sensors is also strong at lower SO2 mixing ratios (< 25 ppb, for which they exhibit an error of less than 2.5 ppb. While some specific results of this study (calibration accuracy, performance of the various algorithms, etc. may differ for measurements of other pollutant species in other areas (e.g., polluted urban regions, the calibration and validation approaches described here should be widely applicable

Molybdenum disulfide nanoflower-chitosan-Au nanoparticles composites based electrochemical sensing platform for bisphenol A determination

International Nuclear Information System (INIS)

Huang, Ke-Jing; Liu, Yu-Jie; Liu, Yan-Ming; Wang, Ling-Ling

2014-01-01

Highlights: • This work constructs a novel electrochemical biosensor for bisphenol A detection. • Flower-like MoS 2 are prepared by a simple hydrothermal procedure. • AuNPs are assembled on MoS 2 nanoflowers modified electrode for signal amplification. • The developed sensor exhibits low detection limit and wide linear range. - Abstract: Two-dimensional transition metal dichalcogenide are attracting increasing attention in electrochemical sensing due to their unique electronic properties. In this work, flower-like molybdenum disulfide (MoS 2 ) was prepared by a simple hydrothermal method. The scanning electron microscopy and transmission electron microscopy images showed the MoS 2 nanoflower had sizes with diameter of about 200 nm and was constructed with many irregular sheets as a petal-like structure with thickness of several nanometers. A novel electrochemical sensor was constructed for the determination of bisphenol A (BPA) based on MoS 2 and chitosan-gold nanoparticles composites modified electrode. The sensor showed an efficient electrocatalytic role for the oxidation of BPA, and the oxidation overpotentials of BPA decreased significantly and the peak current increased greatly compared with bare GCE and other modified electrode. A good linear relationship between the oxidation peak current and BPA concentration was obtained in the range from 0.05 to 100 μM with a detection limit of 5.0 × 10 −9 M (S/N = 3). The developed sensor exhibited high sensitivity and long-term stability, and it was successfully applied for the determination of BPA in different samples. This work indicated MoS 2 nanoflowers were promising in electrochemical sensing and catalytic applications

Electrochemical Impedance Sensors for Monitoring Trace Amounts of NO3 in Selected Growing Media

Directory of Open Access Journals (Sweden)

Seyed Alireza Ghaffari

2015-07-01

Full Text Available With the advent of smart cities and big data, precision agriculture allows the feeding of sensor data into online databases for continuous crop monitoring, production optimization, and data storage. This paper describes a low-cost, compact, and scalable nitrate sensor based on electrochemical impedance spectroscopy for monitoring trace amounts of NO3− in selected growing media. The nitrate sensor can be integrated to conventional microelectronics to perform online nitrate sensing continuously over a wide concentration range from 0.1 ppm to 100 ppm, with a response time of about 1 min, and feed data into a database for storage and analysis. The paper describes the structural design, the Nyquist impedance response, the measurement sensitivity and accuracy, and the field testing of the nitrate sensor performed within tree nursery settings under ISO/IEC 17025 certifications.

Chemical sensors for nuclear industry

International Nuclear Information System (INIS)

Gnanasekaran, K.I.

2012-01-01

Development of chemical sensors for detection of gases at trace levels for applications in nuclear industry will be highlighted. The sensors have to be highly sensitive, reliable and rugged with long term stability to operate in harsh industrial environment. Semiconductor and solid electrolyte based electrochemical sensors satisfy the requirements. Physico-chemical aspects underlying the development of H 2 sensors in sodium and in cover gas circuit of the Fast breeder reactors for its smooth functioning, NH 3 and H 2 S sensors for use in Heavy water production industries and NO x sensors for spent fuel reprocessing plants will be presented. Development of oxygen sensors to monitor the oxygen level in the reactor containments and sodium sensors for detection of sodium leakages will also be discussed. The talk will focus the general aspects of identification of the sensing material for the respective analyte species, development of suitable chemical route for preparing them as fine powders, the need for configuring them in thick film or thin film geometries and their performance. Pulsed laser deposition method, an elegant technique to prepare the high quality thin films of multicomponent oxides is demonstrated for preparation of nanostructured thin films of complex oxides and its use in tailoring the morphology of the complex sensing material in the desired form by optimizing the in-situ growth conditions. (author)

Highly sensitive electrochemical determination of Sunset Yellow based on gold nanoparticles/graphene electrode

International Nuclear Information System (INIS)

Wang, Jin; Yang, Beibei; Wang, Huiwen; Yang, Ping; Du, Yukou

2015-01-01

An electrochemical sensor was prepared using Au nanoparticles and reduced graphene successfully decorated on the glassy carbon electrode (Au/RGO/GCE) through an electrochemical method which was applied to detect Sunset Yellow (SY). The as-prepared electrode was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and electrochemical measurements. The results of cyclic voltammetry (CV) proved that Au/RGO/GCE had the highest catalytic activity for the oxidation of SY as compared with GCE, Au/GCE, and RGO/GCE. Differential pulse voltammetry (DPV) showed that the linear calibration curves for SY on Au/RGO/GCE in the range of 0.002 μM–109.14 μM, and the detection limit was estimated to be 2 nM (S/N = 3). These results suggested that the obtained Au/RGO/GCE was applied to detect SY with high sensitivity, low detection limit and good stability, which provided a promising future for the development of portable sensor in food additives. - Highlights: • An Au/RGO composite was fabricated by electrochemical deposition method. • The oxidation current of SY on the composition is up to 10 μA. • The detection range of SY is 0.002–109.14 μM with a detection limit of 2 nM.

Sensitive determination of citrinin based on molecular imprinted electrochemical sensor

Science.gov (United States)

Atar, Necip; Yola, Mehmet Lütfi; Eren, Tanju

2016-01-01

In this report, a novel molecular imprinted voltammetric sensor based on glassy carbon electrode (GCE) modified with platinum nanoparticles (PtNPs) involved in a polyoxometalate (H3PW12O40, POM) functionalized reduced graphene oxide (rGO) was prepared for the determination of citrinin (CIT). The developed surfaces were characterized by using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) method. CIT imprinted GCE was prepared via electropolymerization process of 80.0 mM pyrrole as monomer in the presence of phosphate buffer solution (pH 6.0) containing 20.0 mM CIT. The linearity range and the detection limit of the developed method were calculated as 1.0 × 10-12-1.0 × 10-10 M and 2.0 × 10-13 M, respectively. In addition, the voltammetric sensor was applied to rye samples. The stability and selectivity of the voltammetric sensor were also reported.

Advances in electrospun carbon fiber-based electrochemical sensing platforms for bioanalytical applications.

Science.gov (United States)

Mao, Xianwen; Tian, Wenda; Hatton, T Alan; Rutledge, Gregory C

2016-02-01

Electrochemical sensing is an efficient and inexpensive method for detection of a range of chemicals of biological, clinical, and environmental interest. Carbon materials-based electrodes are commonly employed for the development of electrochemical sensors because of their low cost, biocompatibility, and facile electron transfer kinetics. Electrospun carbon fibers (ECFs), prepared by electrospinning of a polymeric precursor and subsequent thermal treatment, have emerged as promising carbon systems for biosensing applications since the electrochemical properties of these carbon fibers can be easily modified by processing conditions and post-treatment. This review addresses recent progress in the use of ECFs for sensor fabrication and analyte detection. We focus on the modification strategies of ECFs and identification of the key components that impart the bioelectroanalytical activities, and point out the future challenges that must be addressed in order to advance the fundamental understanding of the ECF electrochemistry and to realize the practical applications of ECF-based sensing devices.

Enzymatic and non-enzymatic electrochemical glucose sensor based on carbon nano-onions

Science.gov (United States)

Mohapatra, Jeotikanta; Ananthoju, Balakrishna; Nair, Vishnu; Mitra, Arijit; Bahadur, D.; Medhekar, N. V.; Aslam, M.

2018-06-01

A high sensitive glucose sensing characteristic has been realized in carbon nano-onions (CNOs). The CNOs of mean size 30 nm were synthesized by an energy-efficient, simple and inexpensive combustion technique. These as-synthesized CNOs could be employed as an electrochemical sensor by covalently immobilizing the glucose oxidase enzyme on them via carbodiimide chemistry. The sensitivity achieved by such a sensor is 26.5 μA mM-1 cm-2 with a linear response in the range of 1-10 mM glucose. Further to improve the catalytic activity of the CNOs and also to make them enzyme free, platinum nanoparticles of average size 2.5 nm are decorated on CNOs. This sensor fabricated using Pt-decorated CNOs (Pt@CNOs) nanostructure has shown an enhanced sensitivity of 21.6 μA mM-1 cm-2 with an extended linear response in the range of 2-28 mM glucose. Through these attempts we demonstrate CNOs as a versatile biosensing platform.

Method of preparing an electrochemical cell in uncharged state

Science.gov (United States)

Shimotake, Hiroshi; Bartholme, Louis G.; Arntzen, John D.

1977-02-01

A secondary electrochemical cell is assembled in an uncharged state for the preparation of a lithium alloy-transition metal sulfide cell. The negative electrode includes a material such as aluminum or silicon for alloying with lithium as the cell is charged. The positive electrode is prepared by blending particulate lithium sulfide, transition metal powder and electrolytic salt in solid phase. The mixture is simultaneously heated to a temperature in excess of the melting point of the electrolyte and pressed onto an electrically conductive substrate to form a plaque. The plaque is assembled as a positive electrode within the cell. During the first charge cycle lithium alloy is formed within the negative electrode and transition metal sulfide such as iron sulfide is produced within the positive electrode.

Utilization of a new optical sensor unit to monitor the electrochemical elimination of selected dyes in water

Science.gov (United States)

Valica, M.; Černá, T.; Hostin, S.

2017-10-01

This paper presents results obtained by developed optical sensor, which consist from multi-wavelength LED light source and two photodetectors capable of measuring the change in optical signal along two different optical paths (absorbance and reflectance measurements). Arduino microcomputer was used for light source management and optical signal data measuring and recording. Analytical validation of developed optical sensor is presented in this paper. The performance of the system has been tested with varying water solution of dyes (malachite green, methyl orange, trypan red). These results show strong correlations between the optical signal response and colour change from the dyes. Sensor was used for continual in-situ monitoring of electrochemical elimination of selected dyes (current density 15.7 mA cm-2, electrolyte volume 4 L and NaCl concentration 2 g L-1). Maximum decolorization level varies with each dye. For malachite green was obtain 92,7 % decolorization (25 min); methyl orange 90,8% (8,5 min) and trypan red 84,7% decolorization after 33 min of electrochemical treatment.

Covalent functionalization of MoS2 nanosheets synthesized by liquid phase exfoliation to construct electrochemical sensors for Cd (II) detection.

Science.gov (United States)

Gan, Xiaorong; Zhao, Huimin; Wong, Kwok-Yin; Lei, Dang Yuan; Zhang, Yaobin; Quan, Xie

2018-05-15

Surface functionalization is an effective strategy in the precise control of electronic surface states of two-dimensional materials for promoting their applications. In this study, based on the strong coordination interaction between the transition-metal centers and N atoms, the surface functionalization of few-layer MoS 2 nanosheets was successfully prepared by liquid phase exfoliation method in N, N-dimethylformamide (DMF), 1-methyl-2-pyrrolidinone, and formamide. The cytotoxicity of surface-functionalized MoS 2 nanosheets was for the first time evaluated by the methylthiazolyldiphenyl-tetrazoliumbromide assays. An electrochemical sensor was constructed based on glass carbon electrode (GCE) modified by MoS 2 nanosheets obtained in DMF, which exhibits relatively higher sensitivity to Cd 2+ detection and lower cytotoxicity against MCF-7 cells. The mechanisms of surface functionalization and selectively detecting Cd 2+ were investigated by density functional theory calculations together with various spectroscopic measurements. It was found that surface-functionalized MoS 2 nanosheets could be generated through Mo-N covalent bonds due to the orbital hybridization between the 5 s orbitals of Mo atoms and the 2p orbitals of N atoms of the solvent molecules. The high selectivity of the sensor is attributed to the coordination reaction between Cd 2+ and O donor atoms of DMF adsorbed on MoS 2 nanosheets. The robust anti-interference is ascribed to the strong binding energy of Cd 2+ and O atoms of DMF. Under the optimum conditions, the electrochemical sensor exhibits highly sensitive and selective assaying of Cd 2+ with a measured detection limit of 0.2 nM and a linear range from 2 nM to 20 μM. Copyright © 2018 Elsevier B.V. All rights reserved.

Toward selective electrochemical 'E-tongue': Potentiometric DO sensor based on sub-micron ZnO-RuO{sub 2} sensing electrode

Energy Technology Data Exchange (ETDEWEB)

Zhuiykov, Serge, E-mail: serge.zhuiykov@csiro.au [CSIRO, Materials Science and Engineering Division, 37 Graham Road, Highett, VIC 3190 (Australia); Kats, Eugene [CSIRO, Materials Science and Engineering Division, 37 Graham Road, Highett, VIC 3190 (Australia); Plashnitsa, Vladimir [Research and Education Centre of Carbon Resources, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan); Miura, Norio [KASTEC, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan)

2011-06-01

Highlights: > We examine ZnO-doped RuO{sub 2} sensing electrode of DO sensor. > Study of ZnO-RuO{sub 2} confirmed the development of high surface-to-volume ratio. > Developed sensing electrode is insensitive to the presence of various dissolved salts. > 20 mol% ZnO-doped RuO{sub 2} sensing electrode enables maximum DO sensitivity. > We conclude that DO sensor based on ZnO-RuO{sub 2} electrode can work at 11-30 deg. C. - Abstract: Planar dissolved oxygen (DO) sensors based on thick-film ZnO-RuO{sub 2} sensing electrodes (SEs) with different mol% of ZnO were prepared on the alumina substrates using a screen-printing method and their structural and electrochemical properties were closely studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), electrochemical impedance spectroscopy (EIS) and energy-dispersive spectroscopy (EDS) techniques. Structural and electrochemical properties of ZnO-RuO{sub 2}-SEs have been investigated. Interference testing ascertained that the DO sensor based on sub-micron ZnO-RuO{sub 2}-SE is insensitive to the presence of various dissolved ions including Cl{sup -}, Li{sup +}, SO{sub 4}{sup 2-}, NO{sup 3-}, Ca{sup 2+}, PO{sub 4}{sup 3-}, Mg{sup 2+}, Na{sup +} and K{sup +} within a concentration range of 10{sup -7} to 10{sup -1} mol/L for DO measurement from 0.5 to 8.0 ppm in the test solution at a temperature range of 11-30 deg. C. These dissolved salts had practically no effect on the sensor's output potential difference response, whereas Br{sup -} ions had some effects at concentration more than 10{sup -3} mol/L. The relationship between DO and the sensor's potential difference was found to be relatively linear with the maximum sensitivity of -50.6 mV per decade was achieved at 20 mol% ZnO at 7.35 pH. The response and recovery time to pH changes for the planar device based on 20 mol% ZnO-RuO{sub 2}-SE was found to be 10 and 25 s

Electrochemical impedance spectroscopy based MEMS sensors for phthalates detection in water and juices

KAUST Repository

Zia, Asif I

2013-06-10

Phthalate esters are ubiquitous environmental and food pollutants well known as endocrine disrupting compounds (EDCs). These developmental and reproductive toxicants pose a grave risk to the human health due to their unlimited use in consumer plastic industry. Detection of phthalates is strictly laboratory based time consuming and expensive process and requires expertise of highly qualified and skilled professionals. We present a real time, non-invasive, label free rapid detection technique to quantify phthalates\\' presence in deionized water and fruit juices. Electrochemical impedance spectroscopy (EIS) technique applied to a novel planar inter-digital (ID) capacitive sensor plays a vital role to explore the presence of phthalate esters in bulk fluid media. The ID sensor with multiple sensing gold electrodes was fabricated on silicon substrate using micro-electromechanical system (MEMS) device fabrication technology. A thin film of parylene C polymer was coated as a passivation layer to enhance the capacitive sensing capabilities of the sensor and to reduce the magnitude of Faradic current flowing through the sensor. Various concentrations, 0.002ppm through to 2ppm of di (2-ethylhexyl) phthalate (DEHP) in deionized water, were exposed to the sensing system by dip testing method. Impedance spectra obtained was analysed to determine sample conductance which led to consequent evaluation of its dielectric properties. Electro-chemical impedance spectrum analyser algorithm was employed to model the experimentally obtained impedance spectra. Curve fitting technique was applied to deduce constant phase element (CPE) equivalent circuit based on Randle\\'s equivalent circuit model. The sensing system was tested to detect different concentrations of DEHP in orange juice as a real world application. The result analysis indicated that our rapid testing technique is able to detect the presence of DEHP in all test samples distinctively.

Electrochemical impedance spectroscopy based MEMS sensors for phthalates detection in water and juices

International Nuclear Information System (INIS)

Zia, Asif I; Syaifudin, A R Mohd; Mukhopadhyay, S C; Yu, P L; Al-Bahadly, I H; Gooneratne, Chinthaka P; Kosel, Juergen; Liao, Tai-Shan

2013-01-01

Phthalate esters are ubiquitous environmental and food pollutants well known as endocrine disrupting compounds (EDCs). These developmental and reproductive toxicants pose a grave risk to the human health due to their unlimited use in consumer plastic industry. Detection of phthalates is strictly laboratory based time consuming and expensive process and requires expertise of highly qualified and skilled professionals. We present a real time, non-invasive, label free rapid detection technique to quantify phthalates' presence in deionized water and fruit juices. Electrochemical impedance spectroscopy (EIS) technique applied to a novel planar inter-digital (ID) capacitive sensor plays a vital role to explore the presence of phthalate esters in bulk fluid media. The ID sensor with multiple sensing gold electrodes was fabricated on silicon substrate using micro-electromechanical system (MEMS) device fabrication technology. A thin film of parylene C polymer was coated as a passivation layer to enhance the capacitive sensing capabilities of the sensor and to reduce the magnitude of Faradic current flowing through the sensor. Various concentrations, 0.002ppm through to 2ppm of di (2-ethylhexyl) phthalate (DEHP) in deionized water, were exposed to the sensing system by dip testing method. Impedance spectra obtained was analysed to determine sample conductance which led to consequent evaluation of its dielectric properties. Electro-chemical impedance spectrum analyser algorithm was employed to model the experimentally obtained impedance spectra. Curve fitting technique was applied to deduce constant phase element (CPE) equivalent circuit based on Randle's equivalent circuit model. The sensing system was tested to detect different concentrations of DEHP in orange juice as a real world application. The result analysis indicated that our rapid testing technique is able to detect the presence of DEHP in all test samples distinctively.

The Electrochemical Characteristics of Hybrid Capacitor Prepared by Chemical Activation of NaOH

International Nuclear Information System (INIS)

Choi, Jeong Eun; Bae, Ga Yeong; Yang, Jeong Min; Lee, Jong Dae

2013-01-01

Active carbons with high specific surface area and micro pore structure were prepared from the coconut shell char using the chemical activation method of NaOH. The preparation process has been optimized through the analysis of experimental variables such as activating chemical agents to char ratio and the flow rate of gas during carbonization. The active carbons with the surface area (2,481m 2 /g) and mean pore size (2.32 nm) were obtained by chemical activation with NaOH. The electrochemical performances of hybrid capacitor were investigated using LiMn 2 O 4 , LiCoO 2 as the positive electrode and prepared active carbon as the negative electrode. The electrochemical behaviors of hybrid capacitor using organic electrolytes (LiPF 6 , TEABF 4 ) were characterized by constant current charge/discharge, cyclic voltammetry, cycle and leakage tests. The hybrid capacitor using LiMn 2 O 4 /AC electrodes had better capacitance than other hybrid systems and was able to deliver a specific energy as high as 131 Wh/kg at a specific power of 1,448 W/kg

Electrochemical Sensor for Bilirubin Detection Using Screen Printed Electrodes Functionalized with Carbon Nanotubes and Graphene

Directory of Open Access Journals (Sweden)

Madasamy Thangamuthu

2018-03-01

Full Text Available Practice oriented point-of-care diagnostics require easy-to-handle, miniaturized, and low-cost analytical tools. In a novel approach, screen printed carbon electrodes (SPEs, which were functionalized with nanomaterials, are employed for selective measurements of bilirubin, which is an important biomarker for jaundice. Multi-walled carbon nanotubes (MWCNT and graphene separately deposited on SPEs provide the core of an electrochemical sensor for bilirubin. The electrocatalytic activity towards bilirubin oxidation (bilirubin to biliverdin was observed at +0.25 V. In addition, a further peak corresponding to the electrochemical conversion of biliverdin into purpurin appeared at +0.48 V. When compared to MWCNT, the graphene type shows a 3-fold lower detection limit (0.3 ± 0.022 nM and 0.1 ± 0.018 nM, respectively, moreover, the graphene type exhibits a larger linear range (0.1–600 µM than MWCNT (0.5–500 µM with a two-fold better sensitivity, i.e., 30 nA µM−1 cm−2, and 15 nA µM−1 cm−2, respectively. The viability is validated through measurements of bilirubin in blood serum samples and the selectivity is ensured by inhibiting common interfering biological substrates using an ionic nafion membrane. The presented approach enables the design and implementation of low cost and miniaturized electrochemical sensors.

Electrochemical Sensor for Bilirubin Detection Using Screen Printed Electrodes Functionalized with Carbon Nanotubes and Graphene.

Science.gov (United States)

Thangamuthu, Madasamy; Gabriel, Willimann Eric; Santschi, Christian; Martin, Olivier J F

2018-03-07

Practice oriented point-of-care diagnostics require easy-to-handle, miniaturized, and low-cost analytical tools. In a novel approach, screen printed carbon electrodes (SPEs), which were functionalized with nanomaterials, are employed for selective measurements of bilirubin, which is an important biomarker for jaundice. Multi-walled carbon nanotubes (MWCNT) and graphene separately deposited on SPEs provide the core of an electrochemical sensor for bilirubin. The electrocatalytic activity towards bilirubin oxidation (bilirubin to biliverdin) was observed at +0.25 V. In addition, a further peak corresponding to the electrochemical conversion of biliverdin into purpurin appeared at +0.48 V. When compared to MWCNT, the graphene type shows a 3-fold lower detection limit (0.3 ± 0.022 nM and 0.1 ± 0.018 nM, respectively), moreover, the graphene type exhibits a larger linear range (0.1-600 µM) than MWCNT (0.5-500 µM) with a two-fold better sensitivity, i.e., 30 nA µM -1 cm -2 , and 15 nA µM -1 cm -2 , respectively. The viability is validated through measurements of bilirubin in blood serum samples and the selectivity is ensured by inhibiting common interfering biological substrates using an ionic nafion membrane. The presented approach enables the design and implementation of low cost and miniaturized electrochemical sensors.

Uniform β-Co(OH)2 disc-like nanostructures prepared by low-temperature electrochemical rout as an electrode material for supercapacitors

Science.gov (United States)

Aghazadeh, Mustafa; Shiri, Hamid Mohammad; Barmi, Abbas-Ali Malek

2013-05-01

Uniform nanostructures of cobalt hydroxide were successfully prepared by a low-temperature electrochemical method via galvanostatically deposition from a 0.005 M Co(NO3)3 bath at 10 °C. The XRD and FT-IR analyses showed that the prepared sample has a single crystalline hexagonal phase of the brucite-like Co(OH)2. Morphological characterization by SEM and TEM revealed that the prepared β-Co(OH)2 was composed of uniform compact disc-like nanostructures with diameters of 40-50 nm. The electrochemical performance of the prepared β-Co(OH)2 was evaluated using cyclic voltammetry and charge-discharge tests. A maximum specific capacitance of 736.5 F g-1 was obtained in aqueous 1 M KOH with the potential range of -0.2-0.5 V (vs. Ag/AgCl) at the scan rate of 10 mV s-1, suggesting the potential application of the prepared nanostructures as an electrode material in electrochemical supercapacitors. The results of this work showed that the low-temperature cathodic electrodeposition method can be recognized as a new and facile route for the synthesis of cobalt hydroxide nanodiscs as a promising candidate for the electrochemical supercapacitors.

A sensitive electrochemical sensor for paracetamole based on a glassy carbon electrode modified with multiwalled carbon nanotubes and dopamine nanospheres functionalized with gold nanoparticles

International Nuclear Information System (INIS)

Liu, Xue; Wang, Ling-Ling; Wang, Ya-Ya; Zhang, Xiao-Yan

2014-01-01

We describe an electrochemical sensor for paracetamole that is based on a glassy carbon electrode modified with multiwalled carbon nanotubes and dopamine nanospheres functionalized with gold nanoparticles. The functionalized nanospheres were prepared by a chemical route and characterized by scanning electron microscopy. The well-dispersed gold nanoparticles were anchored on the dopamine nanosphere via a chemical reduction of the gold precursor. The stepwise fabrication of the modified electrode and its electrochemical response to paracetamole were evaluated using electrochemical impedance spectroscopy and cyclic voltammetry. The modified electrode displayed improved electrocatalytic activity towards paracetamole, a lower oxidation potential (371 mV), and a larger peak current when compared to a bare electrode or other modified electrodes. The kinetic parameters governing the electro-oxidation of paracetamole were studied, and the analytical conditions were optimized. The peak current was linearly related to the concentration of paracetamole in 0.8–400 μM range, and the detection limit was 50 nM (at an SNR of 3). The method was successfully applied to the determination of paracetamole in spiked human urine samples and gave recoveries between 95.3 and 105.2 %. (author)

Preparation and property study of MnO2/CNPs as electrode materials of electrochemical supercapacitors

Directory of Open Access Journals (Sweden)

JIANG Chao

2016-12-01

Full Text Available MnO2 nanorods deposited on carbon nanospheres (MnO2/CNPs as electrode materials of electrochemical supercapacitors have been synthesized via a hydrothermal synthesis.The micro morphologies and phases of the as-prepared MnO2/CNPs were characterized by field emission scanning electro microscopy(FESEM and X-ray diffraction(XRD.The electrochemical properties of nanomaterials were tested by cyclic voltammetry and galvanostatic charge-discharge.At a current density of 0.1 A/g using 1 mol/L Na2SO4 as electrolyte,the as-prepared MnO2/CNPs exhibit excellent specific capacitance of 305.6 F/g,far larger than carbon nanospheres (49.3 F/g.At a current density of 5 A/g,the specific capacitance of MnO2/CNPs is 235 F/g,which is 76.9% of the specific capacitance under 1 A/g current density.These results demonstrated that MnO2/CNPs may show potential application for electrode materials in electrochemical supercapacitors.

High Sensitivity Electrochemical Cholesterol Sensor Utilizing a Vertically Aligned Carbon Nanotube Electrode with Electropolymerized Enzyme Immobilization

Directory of Open Access Journals (Sweden)

Ditsayut Phokharatkul

2009-10-01

Full Text Available In this report, a new cholesterol sensor is developed based on a vertically aligned CNT electrode with two-step electrochemical polymerized enzyme immobilization. Vertically aligned CNTs are selectively grown on a 1 mm2 window of gold coated SiO2/Si substrate by thermal chemical vapor deposition (CVD with gravity effect and water-assisted etching. CNTs are then simultaneously functionalized and enzyme immobilized by electrochemical polymerization of polyaniline and cholesterol enzymes. Subsequently, ineffective enzymes are removed and new enzymes are electrochemically recharged. Scanning electron microscopic characterization indicates polymer-enzyme nanoparticle coating on CNT surface. Cyclic voltammogram (CV measurements in cholesterol solution show the oxidation and reduction peaks centered around 450 and −220 mV, respectively. An approximately linear relationship between the cholesterol concentration and the response current could be observed in the concentration range of 50–300 mg/dl with a sensitivity of approximately 0.22 μA/mg·dl−1, which is considerably higher compared to previously reported CNT bioprobe. In addition, good specificity toward glucose, uric acid acetaminophen and ascorbic acid have been obtained. Moreover, sensors have satisfactory stability, repeatability and life time. Therefore, the electropolymerized CNT bioprobe is promising for cholesterol detection in normal cholesterol concentration in human blood.

Sensing molecular properties by ATR-SPP Raman spectroscopy on electrochemically structured sensor chips

International Nuclear Information System (INIS)

Zerulla, D.; Isfort, G.; Koelbach, M.; Otto, A.; Schierbaum, K.

2003-01-01

The use of electrochemically structured Al surfaces as sensor arrays for combinatorial chemistry and its detection via microscopic laser techniques from very small volumes has been explored. The methodology is based on three different techniques which will be discussed separately: firstly, attenuated total reflection (ATR) is used in connection with surface-plasmon-polariton (SPP) excitation. A thin Al layer, evaporated on sapphire or quartz and covered with a naturally grown oxide layer, provides an optimum enhancement and confinement of the electrical field close to the surface. This is revealed by calculations and experimental data. Secondly, a Raman microscope is applied, enabling chemical spot analysis in the visible and UV range with a lateral resolution close to the diffraction limit. Finally, its application to investigate electrochemically structured Al films is discussed

Disposable electrochemical sensor to evaluate the phytoremediation of the aquatic plant Lemna minor L. toward Pb(2+) and/or Cd(2+).

Science.gov (United States)

Neagu, Daniela; Arduini, Fabiana; Quintana, Josefina Calvo; Di Cori, Patrizia; Forni, Cinzia; Moscone, Danila

2014-07-01

In this work a miniaturized and disposable electrochemical sensor was developed to evaluate the cadmium and lead ion phytoremediation potential by the floating aquatic macrophyte Lemna minor L. The sensor is based on a screen-printed electrode modified "in-situ" with bismuth film, which is more environmentally friendly than the mercury-based sensor usually adopted for lead and cadmium ion detection. The sensor was coupled with a portable potentiostat for the simultaneous measurement of cadmium and lead ions by stripping analysis. The optimized analytical system allows the simultaneous detection of both heavy metals at the ppb level (LOD equal to 0.3 and 2 ppb for lead and cadmium ions, respectively) with the advantage of using a miniaturized and cost-effective system. The sensor was then applied for the evaluation of Pb(2+) or/and Cd(2+) uptake by measuring the amount of the heavy metals both in growth medium and in plant tissues during 1 week experiments. In this way, the use of Lemna minor coupled with a portable electrochemical sensor allows the set up of a model system able both to remove the heavy metals and to measure "in-situ" the magnitude of heavy metal removal.

Nanoporous gold microelectrode prepared from potential modulated electrochemical alloying–dealloying in ionic liquid

International Nuclear Information System (INIS)

Jiang, Junhua; Wang, Xinying; Zhang, Lei

2013-01-01

Highlights: • A green chemistry method for producing nanoporous gold microelectrode was studied. • An ionic liquid plating bath was utilized for electrochemical alloying–dealloying. • Nanostructures of gold surface layers can be tuned by modulating potential. • Nanoporous gold microelectrode has high surface area and merit of a microelectrode. • Nitrite oxidation and reduction on nanoporous gold microelectrode were studied. -- Abstract: Nanoporous gold (NPG) microelectrodes with high surface area and open pore network were successfully prepared by applying modulated potential to a polycrystalline Au-disk microelectrode in ionic liquid electrolyte containing ZnCl 2 at elevated temperature. During cathodic process, Zn is electrodeposited and interacted with Au microdisk substrate to form a AuZn alloy phase. During subsequent anodic process, Zn is selectively dissolved from the alloy phase, leading to the formation of a NPG layer which can grow with repetitive potential modulation. Scanning-electron microscope and energy dispersive X-ray microscope measurements show that the NPG microelectrodes possessing nanoporous structures can be tuned via potential modulation, and chemically contain a small amount of Zn whose presence has no obvious influence on electrochemical responses of the electrodes. Steady-state and cyclic voltammetric studies suggest that the NPG microelectrodes have high surface area and keep diffusional properties of a microelectrode. Electrochemical nitrite reduction and oxidation are studied as model reactions to demonstrate potential applications of the NPG microelectrodes in electrocatalysis and electroanalysis. These facts suggest that the potential-modulated electrochemical alloying/dealloying in ionic liquid electrolyte offers a convenient green-chemistry method for the preparation of nanoporous microelectrodes

A highly sensitive electrochemical sensor for simultaneous determination of hydroquinone and bisphenol A based on the ultrafine Pd nanoparticle@TiO2 functionalized SiC

International Nuclear Information System (INIS)

Yang, Long; Zhao, Hui; Fan, Shuangmei; Li, Bingchan; Li, Can-Peng

2014-01-01

Graphical abstract: The illustration of Pd@TiO 2 –SiC nanohybrids simultaneous sensing hydroquinone and bisphenol A by an electrochemical strategy. - Highlights: • TiO 2 –SiC was successfully prepared by a facile generic in situ growth strategy. • Ultrafine Pd NPs with a uniform size of ∼2.3 nm monodispersed on TiO 2 –SiC surface. • Electrochemical simultaneous determination of HQ and BPA was established. • Ultrafine metal NPs@metal oxide–SiC may be extended to other applications. - Abstract: A titanium dioxide–silicon carbide nanohybrid (TiO 2 –SiC) with enhanced electrochemical performance was successfully prepared through a facile generic in situ growth strategy. Monodispersed ultrafine palladium nanoparticles (Pd NPs) with a uniform size of ∼2.3 nm were successfully obtained on the TiO 2 –SiC surface via a chemical reduction method. The Pd-loaded TiO 2 –SiC nanohybrid (Pd@TiO 2 –SiC) was characterized by transmission electron microscopy and X-ray diffractometry. A method for the simultaneous electrochemical determination of hydroquinone (HQ) and bisphenol A (BPA) using a Pd@TiO 2 –SiC nanocomposite-modified glassy carbon electrode was established. Utilizing the favorable properties of Pd NPs, the Pd@TiO 2 –SiC nanohybrid-modified glassy carbon electrode exhibited electrochemical performance superior to those of TiO 2 –SiC and SiC. Differential pulse voltammetry was successfully used to simultaneously quantify HQ and BPA within the concentration range of 0.01–200 μM under optimal conditions. The detection limits (S/N = 3) of the Pd@TiO 2 –SiC nanohybrid electrode for HQ and BPA were 5.5 and 4.3 nM, respectively. The selectivity of the electrochemical sensor was improved by introducing 10% ethanol to the buffer medium. The practical application of the modified electrode was demonstrated by the simultaneous detection of HQ and BPA in tap water and wastewater samples. The simple and straightforward strategy presented in this

Ion sensors based on novel fiber organic electrochemical transistors for lead ion detection.

Science.gov (United States)

Wang, Yuedan; Zhou, Zhou; Qing, Xing; Zhong, Weibing; Liu, Qiongzhen; Wang, Wenwen; Li, Mufang; Liu, Ke; Wang, Dong

2016-08-01

Fiber organic electrochemical transistors (FECTs) based on polypyrrole and nanofibers have been prepared for the first time. FECTs exhibited excellent electrical performances, on/off ratios up to 10(4) and low applied voltages below 2 V. The ion sensitivity behavior of the fiber organic electrochemical transistors was investigated. It exhibited that the transfer curve of FECTs shifted to lower gate voltage with increasing cations concentration, the sensitivity reached to 446 μA/dec in the 10(-5)-10(-2) M Pb(2+) concentration range. The ion selective properties of the FECTs have also been systematically studied for the detection of potassium, calcium, aluminum, and lead ions. The devices with different cations showed great difference in response curves. It was suitable for selectively monitoring Pb(2+) with respect to other cations. The results indicated FECTs were very effective for electrochemical sensing of lead ion, which opened a promising perspective for wearable electronics in healthcare and biological application. Graphical Abstract The schematic diagram of fiber organic electrochemical transistors based on polypyrrole and nanofibers for ion sensing.

Graphene Ink Film Based Electrochemical Detector for Paracetamol Analysis

Directory of Open Access Journals (Sweden)

Li Fu

2018-01-01

Full Text Available Graphene ink is a commercialized product in the graphene industry with promising potential application in electronic device design. However, the limitation of the graphene ink is its low electronic performance due to the ink preparation protocol. In this work, we proposed a simple post-treatment of graphene ink coating via electrochemical oxidation. The electronic conductivity of the graphene ink coating was enhanced as expected after the treatment. The proposed electrochemical oxidation treatment also exposes the defects of graphene and triggered an electrocatalytic reaction during the sensing of paracetamol (PA. The overpotential of redox is much lower than conventional PA redox potential, which is favorable for avoiding the interference species. Under optimum conditions, the graphene ink-based electrochemical sensor could linearly detect PA from 10 to 500 micro molar (μM, with a limit of detection of 2.7 μM.

Inkjet printing of nanoporous gold electrode arrays on cellulose membranes for high-sensitive paper-like electrochemical oxygen sensors using ionic liquid electrolytes.

Science.gov (United States)

Hu, Chengguo; Bai, Xiaoyun; Wang, Yingkai; Jin, Wei; Zhang, Xuan; Hu, Shengshui

2012-04-17

A simple approach to the mass production of nanoporous gold electrode arrays on cellulose membranes for electrochemical sensing of oxygen using ionic liquid (IL) electrolytes was established. The approach, combining the inkjet printing of gold nanoparticle (GNP) patterns with the self-catalytic growth of these patterns into conducting layers, can fabricate hundreds of self-designed gold arrays on cellulose membranes within several hours using an inexpensive inkjet printer. The resulting paper-based gold electrode arrays (PGEAs) had several unique properties as thin-film sensor platforms, including good conductivity, excellent flexibility, high integration, and low cost. The porous nature of PGEAs also allowed the addition of electrolytes from the back cellulose membrane side and controllably produced large three-phase electrolyte/electrode/gas interfaces at the front electrode side. A novel paper-based solid-state electrochemical oxygen (O(2)) sensor was therefore developed using an IL electrolyte, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF(6)). The sensor looked like a piece of paper but possessed high sensitivity for O(2) in a linear range from 0.054 to 0.177 v/v %, along with a low detection limit of 0.0075% and a short response time of less than 10 s, foreseeing its promising applications in developing cost-effective and environment-friendly paper-based electrochemical gas sensors.

Development of a sensor prepared by entrapment of MIP particles in electrosynthesised polymer films for electrochemical detection of ephedrine.

Science.gov (United States)

Mazzotta, E; Picca, R A; Malitesta, C; Piletsky, S A; Piletska, E V

2008-02-28

A voltammetric sensor for (-)-ephedrine has been prepared by a novel approach based on immobilisation of an imprinted polymer for ephedrine (MIPE) in an electrosynthesised polypyrrole (PPY) film. Composite films were grown potentiostatically at 1.0 V vs. Pt (QRE) on a glassy carbon electrode using an unconventional "upside-down" (UD) geometry for the three-electrode cell. As a consequence, a high MIP loading was obtained, as revealed by SEM. The sensor response was evaluated, after overoxidation of PPY matrix, by cyclic voltammetry after pre-concentration in a buffered solution of analyte in 0.5-3 mM concentration range. An ephedrine peak at approximately 0.9 V increasing with concentration and saturating at high concentrations was evident. PPY-modified electrode showed a response, which was distinctly lower than the MIP response for the same concentration of the template. The effect of potential interferences including compounds usually found in human fluids (ascorbic acid, uric acid, urea, glucose, sorbitol, glycine, dopamine) was examined.

A novel electrochemical sensor based on metal-organic framework for electro-catalytic oxidation of L-cysteine.

Science.gov (United States)

Hosseini, Hadi; Ahmar, Hamid; Dehghani, Ali; Bagheri, Akbar; Tadjarodi, Azadeh; Fakhari, Ali Reza

2013-04-15

A novel electrochemical sensor based on Au-SH-SiO₂ nanoparticles supported on metal-organic framework (Au-SH-SiO₂@Cu-MOF) has been developed for electrocatalytic oxidation and determination of L-cysteine. The Au-SH-SiO₂@Cu-MOF was characterized by scanning electron microscopy, transmission electron microscopy, x-ray diffraction and cyclic voltammetry. The electrochemical behavior of L-cysteine at the Au-SH-SiO₂@Cu-MOF was investigated by cyclic voltammetry. The Au-SH-SiO₂@Cu-MOF showed a very efficient electrocatalytic activity for the oxidation of L-cysteine in 0.1 M phosphate buffer solution (pH 5.0). The oxidation overpotentials of L-cysteine decreased significantly and their oxidation peak currents increased dramatically at Au-SH-SiO₂@Cu-MOF. The potential utility of the sensor was demonstrated by applying it to the analytical determination of L-cysteine concentration. The results showed that the electrocatalytic current increased linearly with the L-cysteine concentration in the range of 0.02-300 μM and the detection limit was 0.008 μM. Finally, the sensor was applied to determine L-cysteine in water and biological samples. Copyright © 2012 Elsevier B.V. All rights reserved.

A reagentless non-enzymatic hydrogen peroxide sensor presented using electrochemically reduced graphene oxide modified glassy carbon electrode

Energy Technology Data Exchange (ETDEWEB)

Mutyala, Sankararao; Mathiyarasu, Jayaraman, E-mail: al_mathi@yahoo.com

2016-12-01

Herein, we report a simple, facile and reproducible non-enzymatic hydrogen peroxide (H{sub 2}O{sub 2}) sensor using electrochemically reduced graphene oxide (ERGO) modified glassy carbon electrode (GCE). The modified electrode was characterized by Fourier transform infrared (FT-IR), UV–Visible, scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. Cyclic voltammetric (CV) analysis revealed that ERGO/GCE exhibited virtuous charge transfer properties for a standard redox systems and showed excellent performance towards electroreduction of H{sub 2}O{sub 2}. Amperometric study using ERGO/GCE showed high sensitivity (0.3 μA/μM) and faster response upon the addition of H{sub 2}O{sub 2} at an applied potential of − 0.25 V vs. Ag/AgCl. The detection limit is assessed to be 0.7 μM (S/N = 3) and the time to reach a stable study state current is < 3 s for a linear range of H{sub 2}O{sub 2} concentration (1–16 μM). In addition, the modified electrode exhibited good reproducibility and long-term stability. - Graphical abstract: We presented a reagentless non-enzymatic hydrogen peroxide sensor using electrochemically reduced graphene oxide material. - Highlights: • A facile green procedure proposed for high quality graphene synthesis using electrochemical reduction of graphene oxide • A simple, facile and reagentless non-enzymatic hydrogen peroxide sensor developed using ERGO/GCE. • ERGO/GCE exhibited high sensitivity, selectivity and finite limit of detection for H{sub 2}O{sub 2} sensing at low overpotential. • ERGO/GCE exhibited long term stability and good reproducibility.

A reagentless non-enzymatic hydrogen peroxide sensor presented using electrochemically reduced graphene oxide modified glassy carbon electrode

International Nuclear Information System (INIS)

Mutyala, Sankararao; Mathiyarasu, Jayaraman

2016-01-01

Herein, we report a simple, facile and reproducible non-enzymatic hydrogen peroxide (H 2 O 2 ) sensor using electrochemically reduced graphene oxide (ERGO) modified glassy carbon electrode (GCE). The modified electrode was characterized by Fourier transform infrared (FT-IR), UV–Visible, scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. Cyclic voltammetric (CV) analysis revealed that ERGO/GCE exhibited virtuous charge transfer properties for a standard redox systems and showed excellent performance towards electroreduction of H 2 O 2 . Amperometric study using ERGO/GCE showed high sensitivity (0.3 μA/μM) and faster response upon the addition of H 2 O 2 at an applied potential of − 0.25 V vs. Ag/AgCl. The detection limit is assessed to be 0.7 μM (S/N = 3) and the time to reach a stable study state current is < 3 s for a linear range of H 2 O 2 concentration (1–16 μM). In addition, the modified electrode exhibited good reproducibility and long-term stability. - Graphical abstract: We presented a reagentless non-enzymatic hydrogen peroxide sensor using electrochemically reduced graphene oxide material. - Highlights: • A facile green procedure proposed for high quality graphene synthesis using electrochemical reduction of graphene oxide • A simple, facile and reagentless non-enzymatic hydrogen peroxide sensor developed using ERGO/GCE. • ERGO/GCE exhibited high sensitivity, selectivity and finite limit of detection for H 2 O 2 sensing at low overpotential. • ERGO/GCE exhibited long term stability and good reproducibility.

New molecular imprinted voltammetric sensor for determination of ochratoxin A

Energy Technology Data Exchange (ETDEWEB)

Yola, Mehmet Lütfi, E-mail: mehmetyola@gmail.com [Department of Metallurgical and Materials Engineering, Faculty of Engineering, Sinop University, Sinop (Turkey); Gupta, Vinod Kumar, E-mail: vinodfcy@iitr.ac.in [Indian Institute of Technology, Department of Chemistry, Roorkee, Roorkee 247667 (India); Department of Applied Chemistry, University of Johannesburg, Johannesburg (South Africa); Atar, Necip [Department of Chemical Engineering, Faculty of Engineering, Pamukkale University, Denizli (Turkey)

2016-04-01

In this report, a novel molecular imprinted voltammetric sensor based on silver nanoparticles (AgNPs) involved in a polyoxometalate (H{sub 3}PW{sub 12}O{sub 40}, POM) functionalized reduced graphene oxide (rGO) modified glassy carbon electrode (GCE) was presented for determination of ochrattoxin A (OCH). The developed surfaces were characterized using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) method. OCH imprinted GCE was prepared via electropolymerization process of 100 mM phenol as monomer in the presence of phosphate buffer solution (pH 6.0) containing 25 mM OCH. The linearity range and the detection limit of the method were calculated as 5.0 × 10{sup −11} − 1.5 × 10{sup −9} M and 1.6 × 10{sup −11} M, respectively. The voltammetric sensor was applied to grape juice and wine samples with good selectivity and recovery. The stability of the voltammetric sensor was also reported. - Highlights: • Ochratoxin A-imprinted electrochemical sensor is developed for the sensitive detection of ochratoxin A • The nanomaterial and ochratoxin A-imprinted surfaces were characterized by several methods • Ochratoxin A-imprinted electrochemical sensor is sensitive and selective in analysis of food • Ochratoxin A-imprinted electrochemical sensor is preferred to the other methods.

New molecular imprinted voltammetric sensor for determination of ochratoxin A

International Nuclear Information System (INIS)

Yola, Mehmet Lütfi; Gupta, Vinod Kumar; Atar, Necip

2016-01-01

In this report, a novel molecular imprinted voltammetric sensor based on silver nanoparticles (AgNPs) involved in a polyoxometalate (H_3PW_1_2O_4_0, POM) functionalized reduced graphene oxide (rGO) modified glassy carbon electrode (GCE) was presented for determination of ochrattoxin A (OCH). The developed surfaces were characterized using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) method. OCH imprinted GCE was prepared via electropolymerization process of 100 mM phenol as monomer in the presence of phosphate buffer solution (pH 6.0) containing 25 mM OCH. The linearity range and the detection limit of the method were calculated as 5.0 × 10"−"1"1 − 1.5 × 10"−"9 M and 1.6 × 10"−"1"1 M, respectively. The voltammetric sensor was applied to grape juice and wine samples with good selectivity and recovery. The stability of the voltammetric sensor was also reported. - Highlights: • Ochratoxin A-imprinted electrochemical sensor is developed for the sensitive detection of ochratoxin A • The nanomaterial and ochratoxin A-imprinted surfaces were characterized by several methods • Ochratoxin A-imprinted electrochemical sensor is sensitive and selective in analysis of food • Ochratoxin A-imprinted electrochemical sensor is preferred to the other methods

Preparation and characterization of zinc oxide nanoparticles and their sensor applications for electrochemical monitoring of nucleic acid hybridization.

Science.gov (United States)

Yumak, Tugrul; Kuralay, Filiz; Muti, Mihrican; Sinag, Ali; Erdem, Arzum; Abaci, Serdar

2011-09-01

In this study, ZnO nanoparticles (ZNP) of approximately 30 nm in size were synthesized by the hydrothermal method and characterized by X-ray diffraction (XRD), Braun-Emmet-Teller (BET) N2 adsorption analysis and transmission electron microscopy (TEM). ZnO nanoparticles enriched with poly(vinylferrocenium) (PVF+) modified single-use graphite electrodes were then developed for the electrochemical monitoring of nucleic acid hybridization related to the Hepatitis B Virus (HBV). Firstly, the surfaces of polymer modified and polymer-ZnO nanoparticle modified single-use pencil graphite electrodes (PGEs) were characterized using scanning electron microscopy (SEM). The electrochemical behavior of these electrodes was also investigated using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Subsequently, the polymer-ZnO nanoparticle modified PGEs were evaluated for the electrochemical detection of DNA based on the changes at the guanine oxidation signals. Various modifications in DNA oligonucleotides and probe concentrations were examined in order to optimize the electrochemical signals that were generated by means of nucleic acid hybridization. After the optimization studies, the sequence-selective DNA hybridization was investigated in the case of a complementary amino linked probe (target), or noncomplementary (NC) sequences, or target and mismatch (MM) mixture in the ratio of (1:1). Copyright © 2011 Elsevier B.V. All rights reserved.

The Electrochemical Characteristics of Hybrid Capacitor Prepared by Chemical Activation of NaOH

Energy Technology Data Exchange (ETDEWEB)

Choi, Jeong Eun; Bae, Ga Yeong; Yang, Jeong Min; Lee, Jong Dae [Chungbuk National Univ., Chungju (Korea, Republic of)

2013-06-15

Active carbons with high specific surface area and micro pore structure were prepared from the coconut shell char using the chemical activation method of NaOH. The preparation process has been optimized through the analysis of experimental variables such as activating chemical agents to char ratio and the flow rate of gas during carbonization. The active carbons with the surface area (2,481m{sup 2}/g) and mean pore size (2.32 nm) were obtained by chemical activation with NaOH. The electrochemical performances of hybrid capacitor were investigated using LiMn{sub 2}O{sub 4}, LiCoO{sub 2} as the positive electrode and prepared active carbon as the negative electrode. The electrochemical behaviors of hybrid capacitor using organic electrolytes (LiPF{sub 6}, TEABF{sub 4}) were characterized by constant current charge/discharge, cyclic voltammetry, cycle and leakage tests. The hybrid capacitor using LiMn{sub 2}O{sub 4}/AC electrodes had better capacitance than other hybrid systems and was able to deliver a specific energy as high as 131 Wh/kg at a specific power of 1,448 W/kg.

Nanotechnology: A Tool for Improved Performance on Electrochemical Screen-Printed (BioSensors

Directory of Open Access Journals (Sweden)

Elena Jubete

2009-01-01

Full Text Available Screen-printing technology is a low-cost process, widely used in electronics production, especially in the fabrication of disposable electrodes for (biosensor applications. The pastes used for deposition of the successive layers are based on a polymeric binder with metallic dispersions or graphite, and can also contain functional materials such as cofactors, stabilizers and mediators. More recently metal nanoparticles, nanowires and carbon nanotubes have also been included either in these pastes or as a later stage on the working electrode. This review will summarize the use of nanomaterials to improve the electrochemical sensing capability of screen-printed sensors. It will cover mainly disposable sensors and biosensors for biomedical interest and toxicity monitoring, compiling recent examples where several types of metallic and carbon-based nanostructures are responsible for enhancing the performance of these devices.

Fabrication of a methanol chemical sensor based on hydrothermally prepared α-Fe₂O₃ codoped SnO₂ nanocubes.

Science.gov (United States)

Rahman, Mohammed M; Khan, Sher Bahadar; Jamal, A; Faisal, M; Asiri, Abdullah M

2012-06-15

We have prepared calcined α-Fe(2)O(3) codoped SnO(2) nanocubes (NCs) by a hydrothermal method using reducing agents in alkaline medium. The codoped NCs were characterized by UV/vis, FT-IR, and Raman spectroscopy, powder X-ray diffraction (XRD), and field-emission scanning electron microscopy (FESEM). They were deposited on a silver electrode (AgE, surface area, 0.0216 cm(2)) to give a sensor with a fast response towards methanol in liquid phase. The sensor also exhibits good sensitivity and long-term stability, and enhanced electrochemical response. The calibration plot is linear (r(2)=0.9809) over the 0.25 mmol L(-1) to 0.25 mol L(-1) methanol concentration range. The sensitivity is ∼5.79 μA cm(-2)mM(-1), and the detection limit is 0.16 ± 0.02 mmol L(-1) (signal-to-noise ratio, at a SNR of 3). We also discuss possible future prospective uses of this codoped semiconductor nanomaterial in terms of chemical sensing. Copyright © 2012 Elsevier B.V. All rights reserved.

Recent advances in polymer supporting layered double hydroxides nanocomposite for electrochemical biosensors

Science.gov (United States)

Dhanasekaran, T.; Padmanaban, A.; Gnanamoorthy, G.; Manigandan, R.; Praveen Kumar, S.; Stephen, A.; Narayanan, V.

2018-01-01

In recent years, layered double hydroxides (LDHs) materials having emerging due to their ability of intercalate a variety of anions, either organic or inorganic molecules. The most significance of the LDHs has been found potential applications in catalysis, wastewater treatment, and electrochemical sensors. The Mg-Al LDHs (MAL) and Poly-o-phenylenediamine @ Mg-Al LDHs (P-MAL) was prepared via simple one step hydrothermal method. As prepared material was characterized using many techniques such as, the structural and crystal phase was determined from XRD and Raman analyses. The functional groups were depicted using FT-IR spectroscopy. The optical propertied studied using diffuse reflectance spectroscopy UV-vis spectroscopy and the emission property were analyzed from Photoluminescence spectroscopy. The surface morphology and average particle size was analyzed using FESEM microscopy. The prepared polymer composite material P-MAL was further used for highly sensitive electrochemical detection towards dopamine (DA).

Au Nanoparticles Decorated TiO2 Nanotube Arrays as a Recyclable Sensor for Photoenhanced Electrochemical Detection of Bisphenol A.

Science.gov (United States)

Hu, Liangsheng; Fong, Chi-Chun; Zhang, Xuming; Chan, Leo Lai; Lam, Paul K S; Chu, Paul K; Wong, Kwok-Yin; Yang, Mengsu

2016-04-19

A photorefreshable and photoenhanced electrochemical sensing platform for bisphenol A (BPA) detection based on Au nanoparticles (NPs) decorated carbon doped TiO2 nanotube arrays (TiO2/Au NTAs) is described. The TiO2/Au NTAs were prepared by quick annealing of anodized nanotubes in argon, followed by controllable electrodeposition of Au NPs. The decoration of Au NPs not only improved photoelectrochemical behavior but also enhanced electrocatalytic activities of the resulted hybrid NTAs. Meanwhile, the high photocatalytic activity of the NTAs allowed the electrode to be readily renewed without damaging the microstructures and surface states after a short UV treatment. The electrochemical detection of BPA on TiO2/Au NTAs electrode was significantly improved under UV irradiation as the electrode could provide fresh reaction surface continuously and the further increased photocurrent resulting from the improved separation efficiency of the photogenerated electron-hole pairs derived from the consumption of holes by BPA. The results showed that the refreshable TiO2/Au NTAs electrode is a promising sensor for long-term BPA monitoring with the detection limit (S/N = 3) of 6.2 nM and the sensitivity of 2.8 μA·μM(-1)·cm(-2).

Preparation, electrochemical behavior and electrocatalytic activity of chlorogenic acid multi-wall carbon nanotubes as a hydroxylamine sensor

Energy Technology Data Exchange (ETDEWEB)

Zare, Hamid R., E-mail: hrzare@yazduni.ac.ir; Nasirizadeh, Navid; Ajamain, Hamideh; Sahragard, Ali

2011-07-20

Electrochemical characteristics of an electrodeposited chlorogenic acid film on multi-wall carbon nanotubes glassy carbon electrode (CGA-MWCNT-GCE) and its role as a sensor for electrocatalytic oxidation of hydroxylamine are described. Cyclic voltammograms of the CGA-MWCNT-GCE indicate a pair of well-defined and nearly reversible redox couple with the surface confined characteristics at a wide pH range of 2.0-12.0. The charge transfer coefficient, {alpha}, and the charge transfer rate constant, k{sub s}, of CGA adsorbed on MWCNT were calculated 0.48 and 44 {+-} 2 s{sup -1} respectively. The CGA-MWCNT-GCE shows a dramatic increase in the peak current and/or a decrease in the overvoltage of hydroxylamine electrooxidation in comparison with that seen at a CGA modified GCE, MWCNT modified GCE and activated GCE. The kinetic parameters of electron transfer coefficient, {alpha}, the heterogeneous electron transfer rate constant, k', and exchange current, i{sub 0}, for oxidation of hydroxylamine at the modified electrode surface were determined using cyclic voltammetry. Four linear calibration ranges and high repeatability with relative standard deviation of 4.6%, for a series of four successive measurements in 17.7 {mu}M hydroxylamine, are obtained at the CGA-MWCNT-GCE using an amperometric method. Finally, the modified electrode was successfully used for determination of spiked hydroxylamine in two water samples.

Preparation, electrochemical behavior and electrocatalytic activity of chlorogenic acid multi-wall carbon nanotubes as a hydroxylamine sensor

International Nuclear Information System (INIS)

Zare, Hamid R.; Nasirizadeh, Navid; Ajamain, Hamideh; Sahragard, Ali

2011-01-01

Electrochemical characteristics of an electrodeposited chlorogenic acid film on multi-wall carbon nanotubes glassy carbon electrode (CGA-MWCNT-GCE) and its role as a sensor for electrocatalytic oxidation of hydroxylamine are described. Cyclic voltammograms of the CGA-MWCNT-GCE indicate a pair of well-defined and nearly reversible redox couple with the surface confined characteristics at a wide pH range of 2.0-12.0. The charge transfer coefficient, α, and the charge transfer rate constant, k s , of CGA adsorbed on MWCNT were calculated 0.48 and 44 ± 2 s -1 respectively. The CGA-MWCNT-GCE shows a dramatic increase in the peak current and/or a decrease in the overvoltage of hydroxylamine electrooxidation in comparison with that seen at a CGA modified GCE, MWCNT modified GCE and activated GCE. The kinetic parameters of electron transfer coefficient, α, the heterogeneous electron transfer rate constant, k', and exchange current, i 0 , for oxidation of hydroxylamine at the modified electrode surface were determined using cyclic voltammetry. Four linear calibration ranges and high repeatability with relative standard deviation of 4.6%, for a series of four successive measurements in 17.7 μM hydroxylamine, are obtained at the CGA-MWCNT-GCE using an amperometric method. Finally, the modified electrode was successfully used for determination of spiked hydroxylamine in two water samples.

Electrochemical cell with integrated hydrocarbon gas sensor for automobile exhaust gas; Elektrochemische Zelle mit integriertem Kohlenwasserstoff-Gassensor fuer das Automobilabgas

Energy Technology Data Exchange (ETDEWEB)

Biskupski, D.; Moos, R. [Univ. Bayreuth (Germany). Bayreuth Engine Research Center, Lehrstuhl fuer Funktionsmaterialien; Wiesner, K.; Fleischer, M. [Siemens AG, Corporate Technology, CT PS 6, Muenchen (Germany)

2007-07-01

In the future sensors will be necessary to control the compliance with hydrocarbon limiting values, allowing a direct detection of the hydrocarbons. Appropriate sensor-active functional materials are metal oxides, which have a hydrocarbon sensitivity but are also dependent on the oxygen partial pressure. It is proposed that the gas-sensing layer should be integrated into an electrochemical cell. The authors show that the integration of a resistive oxygen sensor into a pump cell allows a defined oxygen concentration level at the sensor layer in any exhaust gas.

The electrochemical reduction processes of solid compounds in high temperature molten salts.

Science.gov (United States)

Xiao, Wei; Wang, Dihua

2014-05-21

Solid electrode processes fall in the central focus of electrochemistry due to their broad-based applications in electrochemical energy storage/conversion devices, sensors and electrochemical preparation. The electrolytic production of metals, alloys, semiconductors and oxides via the electrochemical reduction of solid compounds (especially solid oxides) in high temperature molten salts has been well demonstrated to be an effective and environmentally friendly process for refractory metal extraction, functional materials preparation as well as spent fuel reprocessing. The (electro)chemical reduction of solid compounds under cathodic polarizations generally accompanies a variety of changes at the cathode/melt electrochemical interface which result in diverse electrolytic products with different compositions, morphologies and microstructures. This report summarizes various (electro)chemical reactions taking place at the compound cathode/melt interface during the electrochemical reduction of solid compounds in molten salts, which mainly include: (1) the direct electro-deoxidation of solid oxides; (2) the deposition of the active metal together with the electrochemical reduction of solid oxides; (3) the electro-inclusion of cations from molten salts; (4) the dissolution-electrodeposition process, and (5) the electron hopping process and carbon deposition with the utilization of carbon-based anodes. The implications of the forenamed cathodic reactions on the energy efficiency, chemical compositions and microstructures of the electrolytic products are also discussed. We hope that a comprehensive understanding of the cathodic processes during the electrochemical reduction of solid compounds in molten salts could form a basis for developing a clean, energy efficient and affordable production process for advanced/engineering materials.

Pseudocapacitive properties of nano-structured anhydrous ruthenium oxide thin film prepared by electrostatic spray deposition and electrochemical lithiation/delithiation

Energy Technology Data Exchange (ETDEWEB)

Park, S.H.; Kim, J.Y.; Kim, K.B. [Division of Materials Science and Engineering, Yonsei University, Seoul (Korea, Republic of)

2010-10-15

Nano-structured anhydrous ruthenium oxide (RuO{sub 2}) thin films were prepared using an electrostatic spray deposition (ESD) technique followed by electrochemical lithiation and delithiation. During the electrochemical lithiation process, RuO{sub 2} decomposed to nano-structured metallic ruthenium Ru with the concomitant formation of Li{sub 2}O. Nano-structured RuO{sub 2} was formed upon subsequent electrochemical extraction of Li from the Ru/Li{sub 2}O nanocomposite. Electrochemical lithiation/deliathiation at different charge/discharge rates (C-rate) was used to control the nano-structure of the anhydrous RuO{sub 2}. Electrochemical lithiation/delithiation of the RuO{sub 2} thin film electrode at different C-rates was closely related to the specific capacitance and high rate capability of the nano-structured anhydrous RuO{sub 2} thin film. Nano-structured RuO{sub 2} thin films prepared by electrochemical lithiation and delithiation at 2C rate showed the highest specific capacitance of 653 F g{sup -1} at 20 mV s{sup -1}, which is more than two times higher than the specific capacitance of 269 F g{sup -1} for the as-prepared RuO{sub 2}. In addition, it showed 14% loss in specific capacitance from 653 F g{sup -1} at 20 mV s{sup -1} to 559 F g{sup -1} at 200 mV s{sup -1}, indicating significant improvement in the high rate capability compared to the 26% loss of specific capacitance of the as-prepared RuO{sub 2} electrode from 269 F g{sup -1} at 20 mV s{sup -1} to 198 F g{sup -1} at 200 mV s{sup -1} for the same change in scan rate. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Electrodeposited nickel oxide and graphene modified carbon ionic liquid electrode for electrochemical myglobin biosensor

International Nuclear Information System (INIS)

Sun, Wei; Gong, Shixing; Deng, Ying; Li, Tongtong; Cheng, Yong; Wang, Wencheng; Wang, Lei

2014-01-01

By using ionic liquid 1-hexylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE) as the substrate electrode, graphene (GR) and nickel oxide (NiO) were in situ electrodeposited step by step to get a NiO/GR nanocomposite modified CILE. Myoglobin (Mb) was further immobilized on the surface of NiO/GR/CILE with a Nafion film to get the electrochemical sensor denoted as Nafion/Mb/NiO/GR/CILE. Cyclic voltammetric experiments indicated that a pair of well-defined quasi-reversible redox peaks appeared in pH 3.0 phosphate buffer solution with the formal peak potential (E 0′ ) located at − 0.188 V (vs. SCE), which was the typical characteristics of Mb Fe(III)/Fe(II) redox couples. So the direct electron transfer of Mb was realized and promoted due to the presence of the NiO/GR nanocomposite on the electrode. Based on the cyclic voltammetric data, the electrochemical parameters of Mb on the modified electrode were calculated. The Mb modified electrode showed an excellent electrocatalytic activity towards the reduction of different substrates including trichloroacetic acid and H 2 O 2 . Therefore a third-generation electrochemical Mb biosensor based on NiO/GR/CILE was constructed with good stability and reproducibility. - Highlights: • Graphene and nickel oxide nanocomposites were prepared by electrodeposition. • Electrochemical myoglobin sensor was prepared on a nanocomposite modified electrode. • Direct electrochemistry and electrocatalysis of myglobin were realized

Low cost chemical oxygen demand sensor based on electrodeposited nano-copper film

Directory of Open Access Journals (Sweden)

Hamdy H. Hassan

2018-02-01

Full Text Available A commercially available copper electrical cable and pure Cu disk were used as substrates for the electrodeposition of copper nanoparticles (nano-Cu. The surface morphology of the prepared nano-Cu/Cu electrodes was investigated by scanning electron microscope (SEM and energy dispersive X-ray spectrometer (EDX. The bare copper substrates and the nano-copper modified electrodes were utilized and optimized for electrochemical assay of chemical oxygen demand (COD using glycine as a standard. A comparison was made among the four electrodes (i.e., bare and nano-Cu coated copper cable and pure copper disk as potential COD sensors. The oxidation behavior of glycine was investigated on the surface of the prepared sensors using linear sweep voltammetry (LSV. The results indicate significant enhancement of the electrochemical oxidation of glycine by the deposited nano-Cu. The effects of different deposition parameters, such as Cu2+ concentration, deposition potential, deposition time, pH, and scan rate on the response of the prepared sensors were investigated. Under optimized conditions, the optimal nano-Cu based COD sensor exhibited a linear range of 2–595 mg/L, lower limit of detection (LOD as low as 1.07 mg/L (S/N = 3. The developed method exhibited high tolerance level to Cl− ion where 1.0 M Cl− exhibited minimal influence. The sensor was utilized for the detection of COD in different real water samples. The results obtained were validated using the standard dichromate method.

Dopamine and uric acid electrochemical sensor based on a glassy carbon electrode modified with cubic Pd and reduced graphene oxide nanocomposite.

Science.gov (United States)

Wang, Jin; Yang, Beibei; Zhong, Jiatai; Yan, Bo; Zhang, Ke; Zhai, Chunyang; Shiraishi, Yukihide; Du, Yukou; Yang, Ping

2017-07-01

A cubic Pd and reduced graphene oxide modified glassy carbon electrode (Pd/RGO/GCE) was fabricated to simultaneously detect dopamine (DA) and uric acid (UA) by cyclic voltammetry (CV) and different pulse voltammetry (DPV) methods. Compared with Pd/GCE and RGO/GCE, the Pd/RGO/GCE exhibited excellent electrochemical activity in electrocatalytic behaviors. Performing the Pd/RGO/GCE in CV measurement, the well-defined oxidation peak potentials separation between DA and UA reached to 145mV. By using the differential pulse voltammetry (DPV) technique, the calibration curves for DA and UA were found linear with the concentration range of 0.45-421μM and 6-469.5μM and the detection limit (S/N =3) were calculated to be 0.18μM and 1.6μM, respectively. Furthermore, the Pd/RGO/GCE displayed high selectivity when it was applied into the determination of DA and UA even though in presence of high concentration of interferents. Additionally, the prepared electrochemical sensor of Pd/RGO/GCE demonstrated a practical feasibility in rat urine and serum samples determination. Copyright © 2017 Elsevier Inc. All rights reserved.

Electrochemical Characterization of O2 Plasma Functionalized Multi-Walled Carbon Nanotube Electrode for Legionella pneumophila DNA Sensor

Science.gov (United States)

Park, Eun Jin; Lee, Jun-Yong; Hyup Kim, Jun; Kug Kim, Sun; Lee, Cheol Jin; Min, Nam Ki

2010-08-01

An electrochemical DNA sensor for Legionella pneumophila detection was constructed using O2 plasma functionalized multi-walled carbon nanotube (MWCNT) film as a working electrode (WE). The cyclic voltammetry (CV) results revealed that the electrocatalytic activity of plasma functionalized MWCNT (pf-MWCNT) significantly changed depending on O2 plasma treatment time due to some oxygen containing functional groups on the pf-MWCNT surface. Scanning electron microscope (SEM) images and X-ray photoelectron spectroscopy (XPS) spectra were also presented the changes of their surface morphologies and oxygen composition before and after plasma treatment. From a comparison study, it was found that the pf-MWCNT WEs had higher electrocatalytic activity and more capability of probe DNA immobilization: therefore, electrochemical signal changes by probe DNA immobilization and hybridization on pf-MWCNT WEs were larger than on Au WEs. The pf-MWCNT based DNA sensor was able to detect a concentration range of 10 pM-100 nM of target DNA to detect L. pneumophila.

Graphene prepared by one-pot solvent exfoliation as a highly sensitive platform for electrochemical sensing

Energy Technology Data Exchange (ETDEWEB)

Wu, Can; Cheng, Qin [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Wu, Kangbing, E-mail: kbwu@hust.edu.cn [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Wu, Gang [Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Li, Qing, E-mail: qing_li_2@brown.edu [Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2014-05-01

Highlights: • Graphene was prepared by one-step solvent exfoliation as superior electrode material. • Compared with RGO, prepared graphene exhibited stronger signal enhancement. • A widespread and highly-sensitive electrochemical sensing platform was constructed. - Abstract: Graphene was easily obtained via one-step ultrasonic exfoliation of graphite powder in N-methyl-2-pyrrolidone. Scanning electron microscopy, transmission electron microscopy, Raman and particle size measurements indicated that the exfoliation efficiency and the amount of produced graphene increased with ultrasonic time. The electrochemical properties and analytical applications of the resulting graphene were systematically studied. Compared with the predominantly-used reduced graphene oxides, the obtained graphene by one-step solvent exfoliation greatly enhanced the oxidation signals of various analytes, such as ascorbic acid (AA), dopamine (DA), uric acid (UA), xanthine (XA), hypoxanthine (HXA), bisphenol A (BPA), ponceau 4R, and sunset yellow. The detection limits of AA, DA, UA, XA, HXA, BPA, ponceau 4R, and sunset yellow were evaluated to be 0.8 μM, 7.5 nM, 2.5 nM, 4 nM, 10 nM, 20 nM, 2 nM, and 1 nM, which are much lower than the reported values. Thus, the prepared graphene via solvent exfoliation strategy displays strong signal amplification ability and holds great promise in constructing a universal and sensitive electrochemical sensing platform.

Computer-assisted electrochemical fabrication of a highly selective and sensitive amperometric nitrite sensor based on surface decoration of electrochemically reduced graphene oxide nanosheets with CoNi bimetallic alloy nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Gholivand, Mohammad-Bagher, E-mail: mbgholivand2013@gmail.com [Faculty of Chemistry, Razi University, Kermanshah 671496734 (Iran, Islamic Republic of); Jalalvand, Ali R. [Faculty of Chemistry, Razi University, Kermanshah 671496734 (Iran, Islamic Republic of); Laboratorio de Desarrollo Analítico y Quimiometría (LADAQ), Cátedra de Química Analítica I, Universidad Nacional del Litoral, Ciudad Universitaria, CC 242 (S3000ZAA), Santa Fe (Argentina); Goicoechea, Hector C. [Laboratorio de Desarrollo Analítico y Quimiometría (LADAQ), Cátedra de Química Analítica I, Universidad Nacional del Litoral, Ciudad Universitaria, CC 242 (S3000ZAA), Santa Fe (Argentina)

2014-07-01

For the first time, a novel, robust and very attractive statistical experimental design (ED) using minimum-run equireplicated resolution IV factorial design (Min-Run Res IV FD) coupled with face centered central composite design (FCCCD) and Derringer's desirability function (DF) was developed to fabricate a highly selective and sensitive amperometric nitrite sensor based on electrodeposition of CoNi bimetallic alloy nanoparticles (NPs) on electrochemically reduced graphene oxide (ERGO) nanosheets. The modifications were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), energy dispersive X-ray spectroscopic (EDS), scanning electron microscopy (SEM) techniques. The CoNi bimetallic alloy NPs were characterized using digital image processing (DIP) for particle counting (density estimation) and average diameter measurement. Under the identified optimal conditions, the novel sensor detects nitrite in concentration ranges of 0.1–30.0 μM and 30.0–330.0 μM with a limit of detection (LOD) of 0.05 μM. This sensor selectively detects nitrite even in the presence of high concentration of common ions and biological interferents therefore, we found that the sensor is highly selective. The sensor also demonstrated an excellent operational stability and good antifouling properties. The proposed sensor was used to the determination of nitrite in several foodstuff and water samples. - Highlights: • Eight variables were screened by Min Run Res IV FD to identify the key variables. • Mathematical models for the two studied responses were developed by FCCCD. • By using DF the responses were optimized simultaneously. • The SEM image of the modified electrode was processed by digital image processing. • The sensor was successfully applied to determination of nitrite in real samples.

Computer-assisted electrochemical fabrication of a highly selective and sensitive amperometric nitrite sensor based on surface decoration of electrochemically reduced graphene oxide nanosheets with CoNi bimetallic alloy nanoparticles

International Nuclear Information System (INIS)

Gholivand, Mohammad-Bagher; Jalalvand, Ali R.; Goicoechea, Hector C.

2014-01-01

For the first time, a novel, robust and very attractive statistical experimental design (ED) using minimum-run equireplicated resolution IV factorial design (Min-Run Res IV FD) coupled with face centered central composite design (FCCCD) and Derringer's desirability function (DF) was developed to fabricate a highly selective and sensitive amperometric nitrite sensor based on electrodeposition of CoNi bimetallic alloy nanoparticles (NPs) on electrochemically reduced graphene oxide (ERGO) nanosheets. The modifications were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), energy dispersive X-ray spectroscopic (EDS), scanning electron microscopy (SEM) techniques. The CoNi bimetallic alloy NPs were characterized using digital image processing (DIP) for particle counting (density estimation) and average diameter measurement. Under the identified optimal conditions, the novel sensor detects nitrite in concentration ranges of 0.1–30.0 μM and 30.0–330.0 μM with a limit of detection (LOD) of 0.05 μM. This sensor selectively detects nitrite even in the presence of high concentration of common ions and biological interferents therefore, we found that the sensor is highly selective. The sensor also demonstrated an excellent operational stability and good antifouling properties. The proposed sensor was used to the determination of nitrite in several foodstuff and water samples. - Highlights: • Eight variables were screened by Min Run Res IV FD to identify the key variables. • Mathematical models for the two studied responses were developed by FCCCD. • By using DF the responses were optimized simultaneously. • The SEM image of the modified electrode was processed by digital image processing. • The sensor was successfully applied to determination of nitrite in real samples

A comparison of the microstructures and electrochemical capacitive properties of 2 graphenes prepared by arc discharge method and chemical method

Energy Technology Data Exchange (ETDEWEB)

Zhang, H.; Yang, Y. [Research Inst. of Chemical Defense, Beijing (China); Univ. of Science and Technology, Beijing (China); Cao, G.; Xu, B. [Research Inst. of Chemical Defense, Beijing (China)

2010-07-01

In this study, 2 kinds of graphene materials were prepared using both arc discharge and chemical methods. The pore structures and electrochemical capacitive properties of the materials were investigated. A mesopore structure was obtained for the graphene prepared using the arc discharge method, with a capacitance of 12.9 F/g and a high rate capability when used in electrochemical applications. The graphene prepared with the chemical method demonstrated a more highly developed micropore structure and capacitances greater than 70 F/g. However, rate performance for the graphene was normal. 2 figs.

Rapid diagnosis of multidrug resistance in cancer by electrochemical sensor based on carbon nanotubes-drug supramolecular nanocomposites.

Science.gov (United States)

Zhang, Haijun; Jiang, Hui; Sun, Feifei; Wang, Huangping; Zhao, Juan; Chen, Baoan; Wang, Xuemei

2011-03-15

The multidrug resistance (MDR) in cancer is a major chemotherapy obstacle, rendering many currently available chemotherapeutic drugs ineffective. The aim of this study was to explore the new strategy to early diagnose the MDR by electrochemical sensor based on carbon nanotubes-drug supramolecular interaction. The carbon nanotubes modified glassy carbon electrodes (CNTs/GCE) were directly immersed into the cells suspension of the sensitive leukemia cells K562 and/or its MDR cells K562/A02 to detect the response of the electrochemical probe of daunorubicin (DNR) residues after incubated with cells for 1h. The fresh evidence from the electrochemical studies based on CNTs/GCE demonstrated that the homogeneous, label-free strategy could directly measure the function of cell membrane transporters in MDR cancer cells, identify the cell phenotype (sensitive or MDR). When the different ratios of the sensitive leukemia cells K562 and its MDR ones K562/A02 were applied as a model of MDR levels to simulate the MDR occurrence in cancer, the cathodic peak current showed good linear response to the fraction of MDR with a correlation coefficient of 0.995. Therefore, the MDR fraction can be easily predicted based on the calibration curve of the cathodic peak current versus the fraction of MDR. These results indicated that the sensing strategy could provide a powerful tool for assessment of MDR in cancer. The new electrochemical sensor based on carbon nanotubes-drug supramolecular nanocomposites could represent promising approach in the rapid diagnosis of MDR in cancer. Copyright © 2011 Elsevier B.V. All rights reserved.

Preparation of copper (I) oxide nanohexagon decorated reduced graphene oxide nanocomposite and its application in electrochemical sensing of dopamine

Energy Technology Data Exchange (ETDEWEB)

Sivasubramanian, R., E-mail: rss@psgias.ac.in; Biji, P.

2016-08-15

Highlights: • Cu{sub 2}O nanohexagon–reduced graphene oxide (rGO) nanocomposite has been prepared by in-situ reduction method. • The rGO-Cu{sub 2}O/GCE exhibited excellent catalytic properties for dopamine due to the synergistic action of the nanocomposite. • The proposed sensor is highly selective toward dopamine in the presence of ascorbic acid and uric acid. - Graphical Abstract: - Abstract: An electrochemical sensor using copper (I) oxide nanostructure decorated reduced graphene oxide (rGO) nanocomposite has been proposed for selective detection of dopamine. The rGO–Cu{sub 2}O nanocomposite was synthesized by in-situ chemical reduction method and was characterized using Transmission Electron Microscope (TEM), Energy Dispersive X-ray (EDX) analysis, X-ray Diffraction (XRD) patterns, Fourier Transform Infrared (FTIR), UV–vis and Raman Spectroscopy, respectively. From Cyclic Voltammetric (CV) studies, it was inferred that rGO–Cu{sub 2}O/GCE exhibits excellent electrocatalytic activity toward dopamine, which is attributed to the enhanced conductivity as well as the synergistic effect of the nanocomposite. The sensing was carried out using Differential Pulse Voltammetry (DPV) wherefrom a Limit of Detection (LOD) of 50 nM with a linear range from 10 µM to 900 µM was estimated. The effect of potential interfering agents such as Uric Acid (UA), Ascorbic Acid (AA), glucose, K{sup +}, Na{sup +}, Cl{sup −}, and SO{sub 4}{sup −} ions toward sensing were investigated. The performance of the sensor toward the estimation of dopamine in human blood and urine samples were analyzed. The facile method for the preparation of a nanocomposite in conjunction with the low detection limit and the wide linear range for dopamine sensing is the advantage of this present study.

Electrochemical performance of Li4Mn5O12 nano-crystallites prepared by spray-drying-assisted solid state reactions

International Nuclear Information System (INIS)

Jiang, Y.P.; Xie, J.; Cao, G.S.; Zhao, X.B.

2010-01-01

Nanosized Li 4 Mn 5 O 12 has been synthesized by a spray-drying-assisted solid state method. The effect of spray drying and drying temperature on the microstructure and electrochemical performance of the final products has been investigated. The microstructure of the products has been characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The electrochemical performance of the products has been studied by galvanostatic cycling, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It has been found that the products prepared with a spray-drying pretreatment of the precursor exhibit a smaller grain size and a narrower size distribution than that prepared without the pretreatment. Among the three samples with a precursor pretreatment, that pretreated at 250 o C shows the best electrochemical performance due to the smallest grain size of below 50 nm and the narrowest size distribution.

Electrochemical formation of InP porous nanostructures and its application to amperometric chemical sensors

International Nuclear Information System (INIS)

Sato, Taketomo; Mizohata, Akinori; Fujino, Toshiyuki; Hashizume, Tamotsu

2008-01-01

In this paper, we report the electrochemical formation of the InP porous nanostructures and their feasibility for the application to the amperometric chemical sensors. Our two step electrochemical process consists of the pore formation on a (001) n-type InP substrate and the subsequent etching of pore walls caused by changing the polarity of the InP electrode in a HCl-based electrolyte. By applying the anodic bias to the InP electrode, the high-density array of uniform nanopores was formed on the surface. Next, the cathodic bias was applied to the porous sample to reduce the wall thickness by cathodic decomposition of InP, where the thickness of InP nanowall decreased uniformly along the entire depth of the porous layer. From the amperometric measurements of the porous electrode, it was found that the electrocatalytic activity was much higher than that of the planar electrode. Furthermore, the current sensitivity for the H 2 O 2 detection was much enhanced after the cathodic decomposition process. The InP porous nanostructure formed by the present process is one of the promising structures for the application to the semiconductor-based bio/chemical sensors. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Uniform manganese hexacyanoferrate hydrate nanocubes featuring superior performance for low-cost supercapacitors and nonenzymatic electrochemical sensors

Science.gov (United States)

Pang, Huan; Zhang, Yizhou; Cheng, Tao; Lai, Wen-Yong; Huang, Wei

2015-09-01

Uniform manganese hexacyanoferrate hydrate nanocubes are prepared via a simple chemical precipitation method at room temperature. Due to both micro/mesopores of the Prussian blue analogue and nanocubic structures, the manganese hexacyanoferrate hydrate nanocubes allow the efficient charge transfer and mass transport for electrolyte solution and chemical species. Thus, the manganese hexacyanoferrate hydrate nanocube electrode shows a good rate capability and cycling stability for electrochemical capacitors. Furthermore, electrodes modified with manganese hexacyanoferrate hydrate nanocubes demonstrate a sensitive electrochemical response to hydrogen peroxide (H2O2) in buffer solutions with a high selectivity.Uniform manganese hexacyanoferrate hydrate nanocubes are prepared via a simple chemical precipitation method at room temperature. Due to both micro/mesopores of the Prussian blue analogue and nanocubic structures, the manganese hexacyanoferrate hydrate nanocubes allow the efficient charge transfer and mass transport for electrolyte solution and chemical species. Thus, the manganese hexacyanoferrate hydrate nanocube electrode shows a good rate capability and cycling stability for electrochemical capacitors. Furthermore, electrodes modified with manganese hexacyanoferrate hydrate nanocubes demonstrate a sensitive electrochemical response to hydrogen peroxide (H2O2) in buffer solutions with a high selectivity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04322k

Microfabricated electrochemical sensor for the detection of radiation-induced DNA damage

Energy Technology Data Exchange (ETDEWEB)

Wang, J.; Rivas, G.; Ozsoz, M.; Grant, D.H.; Cai, X.; Parrado, C. [New Mexico State Univ., Las Cruces, NM (United States)

1997-04-01

An electrochemical biosensor protocol for the detection of radiation-induced DNA damage is described. The procedure employs a dsDNA-coated screen-printed electrode and relies on changes in the guanine-DNA oxidation signal upon exposure to ultraviolet radiation. The decreased signal is ascribed primarily to conformational changes in the DNA and to the photoconversion of the guanine-DNA moiety to a nonelectroactive monomeric base product. Factors influencing the response of these microfabricated DNA sensors, such as irradiation time, wavelength, and distance, are explored, and future prospects are discussed. Similar results are given for the use of bare strip electrodes in connection with irradiated DNA solutions. 8 refs., 4 figs.

Preparation and electrochemical characteristics of porous hollow spheres of NiO nanosheets as electrodes of supercapacitors

Science.gov (United States)

Yu, Wei; Jiang, Xinbing; Ding, Shujiang; Li, Ben Q.

2014-06-01

Porous hollow nanospheres (or spherical shells) made of NiO nanosheets are synthesized and tested for the electrochemical performance of the electrodes made of these materials for supercapacitors. Preparation of the NiO sheet hollow spheres starts with synthesis of polystyrene nanospheres with carboxyl groups (CPS), followed by a two-step activation procedure and the subsequent nucleation and growth by electroless deposition of Ni on the CPS core to obtain CPS@Ni core-shell nanoparticles. The CPS core is eliminated and metallic Ni nanoshell is converted into NiO by calcinations at high temperatures. The material properties of as-prepared hollow NiO nanospheres are characterized by TEM, XRD and N2-absorption measurements. The electrochemical characteristics of the electrodes made of these nanostructured NiO materials are determined by the CV and galvanostatic measurements. These electrochemical tests indicate that electrodes made of the NiO nanosheet hollow spheres exhibit an improved reversible capacitance of 600 F g-1 after 1000 cycles at a high current density of 10 A g-1. It is believed that the good electrochemical performance of these electrodes is attributed to the improved OH- transport in the porous network structures associated with the hollow spheres of randomly oriented NiO nanosheets.

A CMOS analog front-end chip for amperometric electrochemical sensors

International Nuclear Information System (INIS)

Li Zhichao; Chen Min; Xiao Jingbo; Chen Jie; Liu Yuntao

2015-01-01

This paper reports a complimentary metal–oxide–semiconductor (CMOS) analog front-end chip for amperometric electrochemical sensors. The chip includes a digital configuration circuit, which can communicate with an external microcontroller by employing an I 2 C interface bus, and thus is highly programmable. Digital correlative double samples technique and an incremental sigma–delta analog to digital converter (Σ–Δ ADC) are employed to achieve a new proposed system architecture with double samples. The chip has been fabricated in a standard 0.18-μm CMOS process with high-precision and high-linearity performance occupying an area of 1.3 × 1.9 mm 2 . Sample solutions with various phosphate concentrations have been detected with a step concentration of 0.01 mg/L. (paper)

Photoinducedly electrochemical preparation of Prussian blue film and electrochemical modification of the film with cetyltrimethylammonium cation

Energy Technology Data Exchange (ETDEWEB)

Liu Shouqing, E-mail: shouqing_liu@hotmail.co [Key Laboratory of Environmental Functional Materials of Jiangsu Province, College of Chemistry and Bioengineering, Suzhou University of Science and Technology, Suzhou 215009 (China); Li Hua; Sun Weihui; Wang Xiaomei; Chen Zhigang [Key Laboratory of Environmental Functional Materials of Jiangsu Province, College of Chemistry and Bioengineering, Suzhou University of Science and Technology, Suzhou 215009 (China); Xu Jingjuan; Ju Huangxian; Chen Hongyuan [Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education, Nanjing University, Nanjing 210093 (China)

2011-04-15

Research highlights: {yields} Cetyltrimethylammonium cations work as counter ions in Prussian blue film was observed and confirmed by cyclic voltammetry, Fourier transform infrared spectroscopy, X-ray powder diffraction measurements, scanning electronic microscopy and transmission electron microscope for the first time. {yields} Because the cetyltrimethylammonium cations in Prussian blue film are hydrophobic, the Prussian blue film is very stable even in alkali solution, which provides a technical basis for fabrication of stable biosensors. - Abstract: This work presents a photoinducedly electrochemical preparation of Prussian blue from a single sodium nitroprusside and insertion of cetyltrimethylammonium cations into Prussian blue as counter ions. The product of photoinducedly electrochemical reactions has a couple of voltammetric peaks at E{sup o} = 0.266 V in 0.2 mol l{sup -1} KCl solution, the measurements of X-ray powder diffraction and FT-IR spectroscopy show that it is Prussian blue (PB). The formation mechanism of a pre-photochemical reaction and subsequent electrochemical reaction is suggested. The cyclic voltammetric treatment of the freshly as-prepared PB film in 1.0 mmol l{sup -1} cetyltrimethylammonium (CTA) bromide solution leads to the insertion of cetyltrimethylammonium cations into the channels of Prussian blue, which substitutes for potassium ions as counter ions in Prussian blue. The Prussian blue containing CTA counter ions shows two couples of voltammetric peaks at E{sup o} = -0.106 V and E{sup o} = 0.249 V in 0.2 mol l{sup -1} KCl solution containing 1.0 mmol l{sup -1} cetyltrimethylammonium bromide. Compared with the electrochemical behaviors of KFeFe(CN){sub 6} in 0.1 mol l{sup -1} KOH alkali solution, CTAFeFe(CN){sub 6} shows relatively durable voltammetric currents due to the hydrophobic effects of cetyltrimethylammonium. The diffusion coefficients for CTA and potassium cations were estimated to be D{sub CTA} 1.25 x 10{sup -12} cm{sup 2} s

Preparation of Glucose Sensor Using Polydimethylsiloxane / Polypyrrole Complex

Science.gov (United States)

Yasuzawa, Mikito; Inoue, Shigeru; Imai, Shinji

New glucose oxidase (GOD) immobilized glucose sensors were prepared by the electropolymerization of 1-(6-D-gluconamidohexyl) pyrrole (GHP) on the platinum wire electrode precoated with the mixture solution of pyrrole derivative GHP, polydimethylsiloxane (PDS) and Nafion. The addition of Nafion into the precoating mixture solution was essential to obtain suitable sensor sensitivity. However, the sensitivity was about the half of that of the electrode without PDS precoating. Although, the introduction of Nafion was effective to improve the long-term stability of the enzyme-immobilized electrode, the electrode prepared using Nafion, PDS and GHP performed excellent long-term stability even at the measurement and storage temperatures of 40°C. Relatively constant response current was obtained over 30 days under the condition of 40°C and over 9 months measured at 25°C. Moreover, the GOD-immobilized GHP polymer film prepared on the electrode precoated with GHP, PDS and Nafion solution, was found to have excellent hemocompatibility from the result of platelet rich plasma contacting test.

Spray pyrolysed Ru:TiO2 thin film electrodes prepared for electrochemical supercapacitor

Science.gov (United States)

Fugare, B. Y.; Thakur, A. V.; Kore, R. M.; Lokhande, B. J.

2018-04-01

Ru doped TiO2 thin films are prepared by using 0.06 M aqueous solution of potassium titanium oxalate (pto), and 0.005 M aqueous solution of ruthenium tri chloride (RuCl3) precursors. The deposition was carried on stainless steel (SS) by using well known ultrasonic spray pyrolysis technique (USPT) at 723° K by maintaining the spray rate 12 cc/min and compressed air flow rate 10 Lmin-1. Prepared Ru:TiO2 thin films were characterized by structurally, morphologically and electrochemically. Deposited RuO2 shows amorphous structure and TiO2 shows tetragonal crystal structure with rutile as prominent phase at very low decomposition temperature. SEM micrographs of RuO2 exhibits porous, interconnected, spherical grains type morphology and TiO2 shows porous, nanorods and nanoplates like morphology and also Ru doped TiO2 shows porous, spherical, granular and nanorods type morphology. The electrochemical cyclic voltammetery shows mixed capacitive behavior. The achieved highest value of specific capacitance 2692 F/g was Ru doped TiO2 electrode in 0.5 M H2SO4.

Investigation of electrochemical actuation by polyaniline nanofibers

Science.gov (United States)

Mehraeen, Shayan; Alkan Gürsel, Selmiye; Papila, Melih; Çakmak Cebeci, Fevzi

2017-09-01

Polyaniline nanofibers have shown promising electrical and electrochemical properties which make them prominent candidates in the development of smart systems employing sensors and actuators. Their electrochemical actuation potential is demonstrated in this study. A trilayer composite actuator based on polyaniline nanofibers was designed and fabricated. Cross-linked polyvinyl alcohol was sandwiched between two polyaniline nanofibrous electrodes as ion-containing electrolyte gel. First, electrochemical behavior of a single electrode was studied, showing reversible redox peak pairs in 1 M HCl using a cyclic voltammetry technique. High aspect ratio polyaniline nanofibers create a porous network which facilitates ion diffusion and thus accelerates redox reactions. Bending displacement of the prepared trilayer actuator was then tested and reported under an AC potential stimulation as low as 0.5 V in a variety of frequencies from 50 to 1000 mHz, both inside 1 M HCl solution and in air. Decay of performance of the composite actuator in air is investigated and it is reported that tip displacement in a solution was stable and repeatable for 1000 s in all selected frequencies.

Preparation and electrochemical properties of polyaniline nanofibers using ultrasonication

Energy Technology Data Exchange (ETDEWEB)

Manuel, James [Department of Chemical and Biological Engineering and Research Institute for Green Energy Convergence Technology, Gyeongsang National University, 900, Gajwa-dong, Jinju 660-701 (Korea, Republic of); Kim, Miso [Department of Materials Engineering and Convergence Technology, Gyeongsang National University, 900, Gajwa-dong, Jinju 660-701 (Korea, Republic of); Fapyane, Deby; Chang, In Seop [School of Environmental Science and Engineering, Gwangju Institute of Science and Technology, 261 Cheomdan Gwagi-ro, Buk-gu, Gwangju 500-712 (Korea, Republic of); Ahn, Hyo-Jun, E-mail: ahj@gnu.ac.kr [Department of Materials Engineering and Convergence Technology, Gyeongsang National University, 900, Gajwa-dong, Jinju 660-701 (Korea, Republic of); Ahn, Jou-Hyeon, E-mail: jhahn@gnu.ac.kr [Department of Chemical and Biological Engineering and Research Institute for Green Energy Convergence Technology, Gyeongsang National University, 900, Gajwa-dong, Jinju 660-701 (Korea, Republic of); Department of Materials Engineering and Convergence Technology, Gyeongsang National University, 900, Gajwa-dong, Jinju 660-701 (Korea, Republic of)

2014-10-15

Highlights: • Nanofibrous structured polyaniline (PANI) was prepared by simple ultrasonication. • PANI nanofibers prepared at 5 °C are uniform with an average diameter of 50 nm. • The conductivity is increased by 2 × 10{sup 8} times after doping with LiClO{sub 4}. • The cell with PANI-LiClO{sub 4} shows good cycle performance at high current densities. - Abstract: Polyaniline nanofibers have been successfully prepared by applying ultrasonic irradiation during oxidative polymerization of aniline in dilute hydrochloric acid and evaluated for suitability in lithium cells after doping with lithium perchlorate salt. Polyaniline nanofibers are confirmed by Fourier transform infrared spectroscopy, Fourier transform Raman spectroscopy, and transmission electron microscopy, and the efficiency of doping is confirmed by DC conductivity measurements at different temperatures. Electrochemical properties of nanofibers are evaluated, of which a remarkable increase in cycle stability is achieved when compared to polyaniline prepared by simple oxidative polymerization of aniline. The cell with nanofibrous polyaniline doped with LiClO{sub 4} delivers an initial discharge capacity value of 86 mA h g{sup −1} at 1 C-rate which is about 60% of theoretical capacity, and the capacity is slightly lowered during cycle and reaches 50% of theoretical capacity after 40 cycles. The cell delivers a stable and higher discharge capacity even at 2 C-rate compared to that of the cell prepared with bulk polyaniline doped with LiClO{sub 4}.

Simple electrochemical sensor for caffeine based on carbon and Nafion-modified carbon electrodes.

Science.gov (United States)

Torres, A Carolina; Barsan, Madalina M; Brett, Christopher M A

2014-04-15

A simple, economic, highly sensitive and highly selective method for the detection of caffeine has been developed at bare and Nafion-modified glassy carbon electrodes (GCE). The electrochemical behaviour of caffeine was examined in electrolyte solutions of phosphate buffer saline, sodium perchlorate, and in choline chloride plus oxalic acid, using analytical determinations by fixed potential amperometry, phosphate buffer saline being the best. Modifications of the GCE surface with poly(3,4-ethylenedioxythiophene) (PEDOT), Nafion, and multi-walled carbon nanotubes were tested in order to evaluate possible sensor performance enhancements, Nafion giving the most satisfactory results. The effect of interfering compounds usually found in samples containing caffeine was examined at GCE without and with Nafion coating, to exclude interferences, and the sensors were successfully applied to determine the caffeine content in commercial beverages and drugs. Copyright © 2013 Elsevier Ltd. All rights reserved.

Gamma radiation grafting process for preparing separator membranes for electrochemical cells

International Nuclear Information System (INIS)

Agostino, V.F. D'; Lee, J.Y.

1982-01-01

An irradiation grafting process for preparing separator membranes for use in electrochemical cells, comprises contacting a polymeric base film with an aqueous solution of a hydrophilic monomer and a polymerization retardant; and irradiating said contacted film to form a graft membrane having low electrical resistivity and having monomer molecules uniformly grafted thereon. In the examples (meth) acrylic acid is grafted on to polyethylene, polypropylene and polytetrafluoroethylene in the presence of ferrous sulphate or cupric sulphate as polymerization retardants. (author)

Nitrogen-Doped Three Dimensional Graphene for Electrochemical Sensing.

Science.gov (United States)

Yan, Jing; Chen, Ruwen; Liang, Qionglin; Li, Jinghong

2015-07-01

The rational assembly and doping of graphene play an crucial role in the improvement of electrochemical performance for analytical applications. Covalent assembly of graphene into ordered hierarchical structure provides an interconnected three dimensional conductive network and large specific area beneficial to electrolyte transfer on the electrode surface. Chemical doping with heteroatom is a powerful tool to intrinsically modify the electronic properties of graphene due to the increased free charge-carrier densities. By incorporating covalent assembly and nitrogen doping strategy, a novel nitrogen doped three dimensional reduced graphene oxide nanostructure (3D-N-RGO) was developed with synergetic enhancement in electrochemical behaviors. The as prepared 3D-N-RGO was further applied for catechol detection by differential pulse voltammetry. It exhibits much higher electrocatalytic activity towards catechol with increased peak current and decreased potential difference between the oxidation and reduction peaks. Owing to the improved electro-chemical properties, the response of the electrochemical sensor varies linearly with the catechol concentrations ranging from 5 µM to 100 µM with a detection limit of 2 µM (S/N = 3). This work is promising to open new possibilities in the study of novel graphene nanostructure and promote its potential electrochemical applications.

An electrochemical sensor device for measuring blood ammonia at the point of care.

Science.gov (United States)

Brannelly, N T; Killard, A J

2017-05-15

The level of ammonia in blood is relevant in a number of medical conditions. While ammonia is a marker of dysfunction, elevated ammonia is itself a serious medical emergency and can lead to significant and permanent neurological impairment if not addressed quickly. Blood ammonia testing is typically performed in the central laboratory. While a number of point of care devices have been developed, these are based on classical enzymatic or colorimetric principles and have not been widely adopted. In this work, an electrochemical sensor device was developed for measuring blood ammonia. The device was based on the deposition of polyaniline nanoparticle films onto screen printed interdigitated electrodes using inkjet printing and their integration into a polymer microfabricated device with a polytetrafluoroethylene membrane. The device required a 52µL serum sample and measured the change in impedance of the sensor with respect to air at 1kHz, 5mV rms. The device was capable of the measurement of ammonia in serum across the physiologically relevant range of 25-200µM (r 2 =0.9984) and had a limit of detection of 12µM (n =3). The device showed no significant issues with common electrochemical interferences in blood. The device was also validated against a commercial spectrophotometric assay which resulted in excellent correlation (r =0.9699, pair (n =12) and could be stored in desiccant for at least five months. Copyright © 2017 Elsevier B.V. All rights reserved.

CMOS Electrochemical Instrumentation for Biosensor Microsystems: A Review

Directory of Open Access Journals (Sweden)

Haitao Li

2016-12-01

Full Text Available Modern biosensors play a critical role in healthcare and have a quickly growing commercial market. Compared to traditional optical-based sensing, electrochemical biosensors are attractive due to superior performance in response time, cost, complexity and potential for miniaturization. To address the shortcomings of traditional benchtop electrochemical instruments, in recent years, many complementary metal oxide semiconductor (CMOS instrumentation circuits have been reported for electrochemical biosensors. This paper provides a review and analysis of CMOS electrochemical instrumentation circuits. First, important concepts in electrochemical sensing are presented from an instrumentation point of view. Then, electrochemical instrumentation circuits are organized into functional classes, and reported CMOS circuits are reviewed and analyzed to illuminate design options and performance tradeoffs. Finally, recent trends and challenges toward on-CMOS sensor integration that could enable highly miniaturized electrochemical biosensor microsystems are discussed. The information in the paper can guide next generation electrochemical sensor design.

Electrochemical system for the control of oxigen atmospheres in UO2 sintering

International Nuclear Information System (INIS)

Caneiro, Alberto; Abriata, J.P.

1980-01-01

The behaviour of an electrochemical pump and of an oxygen sensor, allowing a precise control of the UO 2 stoichiometry in the preparation and analysis of gaseous mixtures of low oxygen contents is described. The correct functioning of the system can be tested by applying Faraday's law. The oxygen partial pressures can be continuously controlled by the sole varation of the current applied to the electrochemical pump. The partial pressure of the system is within the range between x 10 -1 atm and 10 -27 atm at 800 deg C. This system may be utilized for sintering experiments at a laboratory scale. (M.E.L) [es

Electrochemical Preparation of Polyaniline Nanowires with the Used Electrolyte Solution Treated with the Extraction Process and Their Electrochemical Performance

OpenAIRE

Ying Wu; Jixiao Wang; Bin Ou; Song Zhao; Zhi Wang; Shichang Wang

2018-01-01

Electrochemical polymerization of aniline is one of the most promising methods to prepare polyaniline (PANI) materials. However, during this process, the electrolyte solution must be replaced after electropolymerization of a certain time because of the generation and the accumulation of the by-products, which have significant effects on the morphology, purity and properties of PANI products. Treatment and recycling of the used electrolyte solution are worthwhile to study to reduce the high tr...

A Differential Electrochemical Readout ASIC With Heterogeneous Integration of Bio-Nano Sensors for Amperometric Sensing.

Science.gov (United States)

Ghoreishizadeh, Sara S; Taurino, Irene; De Micheli, Giovanni; Carrara, Sandro; Georgiou, Pantelis

2017-10-01

A monolithic biosensing platform is presented for miniaturized amperometric electrochemical sensing in CMOS. The system consists of a fully integrated current readout circuit for differential current measurement as well as on-die sensors developed by growing platinum nanostructures (Pt-nanoS) on top of electrodes implemented with the top metal layer. The circuit is based on the switch-capacitor technique and includes pseudodifferential integrators for concurrent sampling of the differential sensor currents. The circuit further includes a differential to single converter and a programmable gain amplifier prior to an ADC. The system is fabricated in [Formula: see text] technology and measures current within [Formula: see text] with minimum input-referred noise of [Formula: see text] and consumes [Formula: see text] from a [Formula: see text] supply. Differential sensing for nanostructured sensors is proposed to build highly sensitive and offset-free sensors for metabolite detection. This is successfully tested for bio-nano-sensors for the measurement of glucose in submilli molar concentrations with the proposed readout IC. The on-die electrodes are nanostructured and cyclic voltammetry run successfully through the readout IC to demonstrate detection of [Formula: see text].

Preparing electrochemical active hierarchically porous carbons for detecting nitrite in drinkable water

KAUST Repository

Ding, Baojun

2016-01-13

A class of hierarchically porous carbons were prepared by a facile dual-templating approach. The obtained samples were characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, Brunaner-Emmett-Teller measurement and electrochemical work station, respectively. The porous carbons could possess large specific surface area, interconnected pore structures, high conductivity and graphitizing degree. The resulting materials were used to prepare integrated modified electrodes. Based on the experimental results, the as-prepared hierarchically porous graphite (HPG) modified electrode showed the best electroactive performances toward the detection of nitrite with a detection limit of 8.1 × 10-3 mM. This HPG electrode was also repeatable and stable for 6 weeks. Moreover, this electrode was used for the determination of nitrite in drinkable water, and had acceptable recoveries. © The Royal Society of Chemistry 2016.

Micro-Drilling of Polymer Tubular Ultramicroelectrode Arrays for Electrochemical Sensors

Directory of Open Access Journals (Sweden)

Niels B. Larsen

2013-05-01

Full Text Available We present a reproducible fast prototyping procedure based on micro-drilling to produce homogeneous tubular ultramicroelectrode arrays made from poly(3,4-ethylenedioxythiophene (PEDOT, a conductive polymer. Arrays of Ø 100 µm tubular electrodes each having a height of 0.37 ± 0.06 µm were reproducibly fabricated. The electrode dimensions were analyzed by SEM after deposition of silver dendrites to visualize the electroactive electrode area. The electrochemical applicability of the electrodes was demonstrated by voltammetric and amperometric detection of ferri-/ferrocyanide. Recorded signals were in agreement with results from finite element modelling of the system. The tubular PEDOT ultramicroelectrode arrays were modified by prussian blue to enable the detection of hydrogen peroxide. A linear sensor response was demonstrated for hydrogen peroxide concentrations from 0.1 mM to 1 mM.

An electrochemical sensor for gallic acid based on Fe2O3/electro-reduced graphene oxide composite: Estimation for the antioxidant capacity index of wines

International Nuclear Information System (INIS)

Gao, Feng; Zheng, Delun; Tanaka, Hidekazu; Zhan, Fengping; Yuan, Xiaoning; Gao, Fei; Wang, Qingxiang

2015-01-01

A highly sensitive electrochemical sensor for gallic acid (GA), an important polyphenolic compound, was fabricated using the hybrid material of chitosan (CS), fishbone-shaped Fe 2 O 3 (fFe 2 O 3 ), and electrochemically reduced graphene oxide (ERGO) as the sensing matrix. The electrochemical characterization experiments showed that the CS–fFe 2 O 3 –ERGO modified glassy carbon electrode (CS–fFe 2 O 3 –ERGO/GCE) had large surface area, excellent electronic conductivity and high stability. The GA presented a superior electrochemical response on CS–fFe 2 O 3 –ERGO/GCE in comparison with the single-component modified electrode. The electrochemical mechanism and optimal test conditions of GA on the electrode surface were carefully investigated. Under the optimal conditions, the oxidation peak currents in differential pulse voltammetry (DPV) experiments exhibited a good linear relationship with the logarithmic values of GA concentration over the range from 1.0 × 10 −6 M to 1.0 × 10 −4 M. Based on signal-to-noise (S/N) characteristic of 3, the detection limit was estimated to be 1.5 × 10 −7 M. The proposed sensor has also been applied for estimating the antioxidant capacity index of real samples of red and white wines. - Highlights: • Fishbone-shaped Fe 2 O 3 (fFe 2 O 3 ) nanoparticles were synthesized by a simple template-free solvothermal method. • The nanocomposite of fFe 2 O 3 , graphene and chitosan was used as the sensing platform for gallic acid. • The sensor shows a wide linear range and low detection limit for gallic acid. • The antioxidant capacity index of wines was successfully evaluated by the sensor

Characterization of ceramic materials for electrochemical hydrogen sensors

Energy Technology Data Exchange (ETDEWEB)

Serret, P.; Colominas, S. [Electrochemical Methods Laboratory - Analytical Chemistry Department ETS Institut Quimic de Sarria, Universitat Ramon Llull, Via Augusta, 390, 08017 Barcelona (Spain); Reyes, G. [Industrial Engineering Department ETS Institut Quimic de Sarria, Universitat Ramon Llull, Via Augusta, 390, 08017 Barcelona (Spain); Abella, J., E-mail: jordi.abella@iqs.es [Electrochemical Methods Laboratory - Analytical Chemistry Department ETS Institut Quimic de Sarria, Universitat Ramon Llull, Via Augusta, 390, 08017 Barcelona (Spain)

2011-10-15

Accurate and reliable tritium management is of basic importance for the correct operation conditions of the blanket tritium cycle. The Electrochemical Methods Lab at Institut Quimic de Sarria (IQS) is working in the design and development of tritium sensors, based on proton solid state electrolytes to be used in molten lithium-lead eutectic. Different solid electrolyte proton conductors have been synthesized (Sr{sub 3}CaZr{sub 0.9}Ta{sub 1.1}O{sub 8.55}, SrCe{sub 0.95}Yb{sub 0.05}O{sub 3-{alpha}}, CaZr{sub 0.9}In{sub 0.1}O{sub 3-{alpha}}, Ba{sub 3}(Ca{sub 1.18}Nb{sub 1.82})O{sub 9-{alpha}}) in order to be evaluated in a testing apparatus for hydrogen gas. Potentiometric measurements of the synthesized ceramic elements have been performed. In all experiments the working temperature was 500 {sup o}C. The sensors constructed using the proton conductor element Sr{sub 3}CaZr{sub 0.9}Ta{sub 1.1}O{sub 8.55} exhibited stable output potential and its value was close to the theoretical value calculated with the Nernst equation. When the proton conductor elements SrCe{sub 0.95}Yb{sub 0.05}O{sub 3-{alpha}} and CaZr{sub 0.9}In{sub 0.1}O{sub 3-{alpha}} and Ba{sub 3}(Ca{sub 1.18}Nb{sub 1.82})O{sub 9-{alpha}} were used a deviation higher than 100 mV between theoretical and experimental data was obtained.

Imparting improvements in electrochemical sensors: evaluation of different carbon blacks that give rise to significant improvement in the performance of electroanalytical sensing platforms

International Nuclear Information System (INIS)

Vicentini, Fernando Campanhã; Ravanini, Amanda E.; Figueiredo-Filho, Luiz C.S.; Iniesta, Jesús; Banks, Craig E.; Fatibello-Filho, Orlando

2015-01-01

Three different carbon black materials have been evaluated as a potential modifier, however, only one demonstrated an improvement in the electrochemical properties. The carbon black structures were characterised with SEM, XPS and Raman spectroscopy and found to be very similar to that of amorphous graphitic materials. The modifications utilised were constructed by three different strategies (using ultrapure water, chitosan and dihexadecylphosphate). The fabricated sensors are electrochemically characterised using N,N,N',N'-tetramethyl-para-phenylenediamine and both inner-sphere and outer-sphere redox probes, namely potassium ferrocyanide(II) and hexaammineruthenium(III) chloride, in addition to the biologically relevant and electroactive analytes, dopamine (DA) and acetaminophen (AP). Comparisons are made with an edge-plane pyrolytic graphite and glassy-carbon electrode and the benefits of carbon black implemented as a modifier for sensors within electrochemistry are explored, as well as the characterisation of their electroanalytical performances. We reveal significant improvements in the electrochemical performance (excellent sensitivity, faster heterogeneous electron transfer rate (HET)) over that of a bare glassy-carbon and edge-plane pyrolytic graphite electrode and thus suggest that there are substantial advantages of using carbon black as modifier in the fabrication of electrochemical based sensors. Such work is highly important and informative for those working in the field of electroanalysis where electrochemistry can provide portable, rapid, reliable and accurate sensing protocols (bringing the laboratory into the field), with particular relevance to those searching for new electrode materials

Preparation and electrochemical characterization of polyaniline/activated carbon composites as an electrode material for supercapacitors.

Science.gov (United States)

Oh, Misoon; Kim, Seok

2012-01-01

Polyaniline (PANI)/activated carbon (AC) composites were prepared by a chemical oxidation polymerization. To find an optimum ratio between PANI and AC which shows superior electrochemical properties, the preparation was carried out in changing the amount of added aniline monomers. The morphology of prepared composites was investigated by scanning electron microscopy (SEM) and transmission electron microscope (TEM). The structural and thermal properties were investigated by Fourier transform infrared spectra (FT-IR) and thermal gravimetric analysis (TGA), respectively. The electrochemical properties were characterized by cyclic voltammetry (CV). Composites showed a summation of capacitances that consisted of two origins. One is double-layer capacitance by ACs and the other is faradic capacitance by redox reaction of PANI. Fiber-like PANIs are coated on the surface of ACs and they contribute to the large surface for redox reaction. The vacancy among fibers provided the better diffusion and accessibility of ion. High capacitances of composites were originated from the network structure having vacancy made by PANI fibers. It was found that the composite prepared with 5 ml of aniline monomer and 0.25 g of AC showed the highest capacitance. Capacitance of 771 F/g was obtained at a scan rate of 5 mV/s.

Graphene quantum dots prepared from glucose as optical sensor for glucose

Energy Technology Data Exchange (ETDEWEB)

Shehab, Mona, E-mail: mona_shehab@alexu.edu.eg [Materials Science Department, Institute of Graduate Studies & Research, Alexandria University (Egypt); General Bureau of Beheira Governorate, Damanhour, Beheira 22111 (Egypt); Ebrahim, Shaker; Soliman, Moataz [Materials Science Department, Institute of Graduate Studies & Research, Alexandria University (Egypt)

2017-04-15

Quantum Dots (QDs) show promise materials for many technological applications. In this work we utilized a simple route to prepare graphene quantum dots (GQDs) using glucose carbonization. GQDs functionalized with phenylboronic acid receptors were employed as a sensing material for a nonenzymatic glucose sensor. Photoluminance spectra of GQDs were used as a property of optical sensor for glucose. GQDs considered as a good sensing probe because of its low toxicity, high photoluminance, water solubility and excelent photochemical properties. The prepared GQDs were characterized using UV-visible, Raman and photoluminance spectroscopies, X-ray diffraction and high resolution transmission electron microscopy (HRTEM). HRTEM micrographs confirmed the preparation of 7–10 nm GQDs and the emission peak of the GQDs appeared at 450 nm. The developed sensor has linear response to glucose over a concentration range of 4–40 mM with a correlation coefficient of 0.97 and a low detection limit of approximately 3.0 mM.

Electrochemical preparation of MnO2 nanobelts through pulse base-electrogeneration and evaluation of their electrochemical performance

Science.gov (United States)

Aghazadeh, Mustafa; Maragheh, Mohammad Ghannadi; Ganjali, Mohammad Reza; Norouzi, Parviz; Faridbod, Farnoush

2016-02-01

Cathodic electrodeposition of MnO2 from a nitrate solution, via pulsed base (OH-) electrogeneration was performed for the first time. The deposition experiments were performed in a pulse current mode in typical on-times and off-times (i.e. ton = 1 s and toff = 1 s) with a peak current density of 2 mA cm-2 (Ia = 2 mA cm-2). The structural characterizations conducted by XRD and FTIR techniques revealed that the prepared MnO2 is composed of both α and γ phases. Morphological observation by SEM and TEM showed that the prepared MnO2 is made up of nanobelts with uniform shapes (an average diameter and length of 50 nm and 1 μm, respectively). Further electrochemical measurements by cyclic voltammetry and charge-discharge techniques revealed that the prepared MnO2 nanostructures have excellent capacitive behaviors, like a specific capacitance of 235.5 F g-1 and capacity retention of 91.3% after 1000 cycling at the scan rate of 25 mV s-1.

A sensitive electrochemical sensor for in vitro detection of parathyroid hormone based on a MoS2-graphene composite

Science.gov (United States)

Kim, Hyeong-U.; Kim, Hye Youn; Kulkarni, Atul; Ahn, Chisung; Jin, Yinhua; Kim, Yeongseok; Lee, Kook-Nyung; Lee, Min-Ho; Kim, Taesung

2016-10-01

This paper reports a biosensor based on a MoS2-graphene (MG) composite that can measure the parathyroid hormone (PTH) concentration in serum samples from patients. The interaction between PTH and MG was analysed via an electrochemical sensing technique. The MG was functionalized using L-cysteine. Following this, PTH could be covalently immobilized on the MG sensing electrode. The properties of MG were evaluated using scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectrometry. Following optimization of immobilized materials—such as MG, PTH, and alkaline phosphatase (ALP)—the performance of the MG sensor was investigated via cyclic voltammetry, to assess its linearity, repeatability, and reproducibility. Electrochemical impedance spectroscopy was performed on graphene oxide (GO) and MG-modified electrodes to confirm the capture of a monoclonal antibody (MAb) targeting PTH. Furthermore, the ALP-PTH-MG sensor exhibits a linear response towards PTH from artificial serum over a range of 1-50 pg mL-1. Moreover, patient sera (n = 30) were evaluated using the ALP-PTH-MG sensor and compared using standard equipment (Roche E 170). The P-value is less than 0.01 when evaluated with a t-test using Welch’s correction. This implies that the fabricated sensor can be deployed for medical diagnosis.

Investigation of the charge effect on the electrochemical transduction in a quinone-based DNA sensor

DEFF Research Database (Denmark)

Reisberg, S.; Piro, B.; Noel, V.

2008-01-01

To elucidate the mechanism involved in the electrochemical transduction process of a conducting polymer-based DNA sensor, peptide nucleic acids (PNA) were used. PNA are DNA analogues having similar hybridization properties but are neutral. This allows to discriminate the electrostatic effect of D...... strands from the steric hindrance generated on the bioelectrode upon hybridization. It can be concluded that DNA conformational changes are determinant in the transduction process and that the electrostatic effect is negligible....

Electrochemical Sensor for Determination of Parathion Based on Electropolymerization Poly(Safranine Film Electrode

Directory of Open Access Journals (Sweden)

Xingyuan Liu

2011-01-01

Full Text Available Parathion has been determined with voltammetric technique based on a novel sensor fabricated by electropolymerization of safranine on a glassy carbon electrode (GCE. The electrochemical behavior of poly(safranine film electrode and its electrocatalytic activity toward parathion were studied in detail by cyclic voltammetry (CV and linear sweep voltammetry (LSV. All experimental parameters were optimized, and LSV was proposed for its determination. In optimal working conditions, the reduction current of parathion at this poly(safranine-modified electrode exhibited a good linear relationship with parathion concentration in the range of 3.43×10−8 to 3.43×10−5 mol L−1. The detection limit was 1.0×10−8 mol L−1. The high sensitivity and selectivity of the sensor were demonstrated by its practical application for the determination of trace amounts of parathion in fruit samples.

Preparation and electrochemical performances of nanoporous/cracked cobalt oxide layer for supercapacitors

Science.gov (United States)

Gobal, Fereydoon; Faraji, Masoud

2014-12-01

Nanoporous/cracked structures of cobalt oxide (Co3O4) electrodes were successfully fabricated by electroplating of zinc-cobalt onto previously formed TiO2 nanotubes by anodizing of titanium, leaching of zinc in a concentrated alkaline solution and followed by drying and annealing at 400 °C. The structure and morphology of the obtained Co3O4 electrodes were characterized by X-ray diffraction, EDX analysis and scanning electron microscopy. The results showed that the obtained Co3O4 electrodes were composed of the nanoporous/cracked structures with an average pore size of about 100 nm. The electrochemical capacitive behaviors of the nanoporous Co3O4 electrodes were investigated by cyclic voltammetry, galvanostatic charge-discharge studies and electrochemical impedance spectroscopy in 1 M NaOH solution. The electrochemical data demonstrated that the electrodes display good capacitive behavior with a specific capacitance of 430 F g-1 at a current density of 1.0 A g-1 and specific capacitance retention of ca. 80 % after 10 days of being used in electrochemical experiments, indicating to be promising electroactive materials for supercapacitors. Furthermore, in comparison with electrodes prepared by simple cathodic deposition of cobalt onto TiO2 nanotubes(without dealloying procedure), the impedance studies showed improved performances likely due to nanoporous/cracked structures of electrodes fabricated by dealloying of zinc, which provide fast ion and electron transfer routes and large reaction surface area with the ensued fast reaction kinetics.

Electrochemically decorated ZnTe nanodots on single-walled carbon nanotubes for room-temperature NO2 sensor application.

Science.gov (United States)

Kim, Donguk; Park, Ki-Moon; Shanmugam, Rajakumar; Yoo, Bongyoung

2014-11-01

A gas sensor with ZnTe nanodot-modified single-walled carbon nanotubes (SWCNTs) is demonstrated for NO2 detection at room temperature. ZnTe nanodots are electrochemically deposited in an aqueous solution containing ZnSO4, TeO2 and citrate. A deposition potential range of ZnTe formation of -0.65 to -0.9 V is determined by cyclic voltammetry, and an intermetallic ZnTe compound is formed at above 50 degrees C bath. SWCNT-based sensors show the highly sensitive response down to 1 ppm NO2 gas at room temperature. In particular, the sensitivity of ZnTe nanodot-modified SWCNTs is increased by 6 times as compared to that of pristine SWCNT sensors. A selectivity test of SWCNT-ZnTe nanodots sensors is carried out with ammonia gas (NH3) and methanol vapor (MeOH), and the result confirms an excellent selectivity to NO2 gas.

A highly sensitive electrochemical glucose sensor structuring with nickel hydroxide and enzyme glucose oxidase

International Nuclear Information System (INIS)

Mathew, Manjusha; Sandhyarani, N.

2013-01-01

Graphical abstract: A combination of Ni 2+ /Ni 3+ redox couple and glucose oxidase has successfully been exploited for the realization of a highly sensitive glucose sensor for the first time. -- Highlights: • A multilayered glucose biosensor with enhanced sensitivity was fabricated. • Combination of Ni 2+ /Ni 3+ redox couple and glucose oxidase has been exploited for the first time. • Exhibits a lower detection limit of 100 nM with a high sensitivity of 16,840 μA mM −1 cm −2 . • The surface shows a low Michaelis–Menten constant value of 2.4 μM. • Detailed mechanism of sensing was proposed and justified. -- Abstract: A multilayered glucose biosensor with enhanced electron transport was fabricated via the sequential electrodeposition of chitosan gold nanocomposite (CGNC) and nickel hydroxide (Ni(OH) 2 ) on a bare gold electrode and subsequent immobilization of glucose oxidase. A thin film of Ni(OH) 2 deposited on CGNC modified gold electrode serves as an electrochemical redox probe as well as a matrix for the immobilization of glucose oxidase retaining its activity. Electron transport property of CGNC has been exploited to enhance the electron transport between the analyte and electrode. Electrochemical characteristics of the biosensor were studied by cyclic voltammetry and chronoamperometry. Under optimal conditions the biosensor exhibits a linear range from 1 μM to 100 μM with a limit of detection (lod) down to 100 nM. The sensor shows a low Michaelis-Menten constant value of 2.4 μM indicates the high affinity of enzyme to the analyte points to the retained activity of enzyme after immobilization. The present glucose sensor with the high selectivity, sensitivity and stability is promising for practical clinical applications

Electrochemical and Thermal Studies of Prepared Conducting Chitosan Biopolymer Film

International Nuclear Information System (INIS)

Hlaing Hlaing Oo; Kyaw Naing; Kyaw Myo Naing; Tin Tin Aye; Nyunt Wynn

2005-09-01

In this paper, chitosan based conducting bipolymer films were prepared by casting and solvent evaporating technique. All prepared chitosan films were of pale yellow colour, transparent, and smooth. Sulphuric acid was chosen as the cross-linking agent. It enhanced conduction pathway in cross-linked chitosan films. Mechanical properties, solid-state, and thermal behavior of prepared chitosan fimls were studied by means of a material testing machine, powder X-ray diffractometry (XRD), thermogravimetric analysis (TG-DTG), and differential scanning calorimetry (DSC). By the XRD diffraction pattern, high molecular weight of chitosan product indicates the semi-crystalline nature, but the prepared chitosan film and doped chitosan film indicate significantly lower in crystallinity prove which of the amorphous characteristics. In addition, DSC thermogram of pure chitosan film exhibited exothermic peak around at 300 C, indicating polymer decomposition of chitosan molecules in chitosan films. Furthermore, these DSC thermograms clearly showed that while pure chitosan film display exothermal decomposition, the doped chitosan films mainly endothermic characteristics. The ionic conductivity of doped chitosan films were in the order of 10 to 10 S cm , which is in the range of semi-conductor. These results showed that cross-linked chitoson films may be used as polymer electrolyte film to fabricate solid state electrochemical cells

Detection of methyl salicylate using bi-enzyme electrochemical sensor consisting salicylate hydroxylase and tyrosinase.

Science.gov (United States)

Fang, Yi; Bullock, Hannah; Lee, Sarah A; Sekar, Narendran; Eiteman, Mark A; Whitman, William B; Ramasamy, Ramaraja P

2016-11-15

Volatile organic compounds have been recognized as important marker chemicals to detect plant diseases caused by pathogens. Methyl salicylate has been identified as one of the most important volatile organic compounds released by plants during a biotic stress event such as fungal pathogen infection. Advanced detection of these marker chemicals could help in early identification of plant diseases and has huge significance for agricultural industry. This work describes the development of a novel bi-enzyme based electrochemical biosensor consisting of salicylate hydroxylase and tyrosinase enzymes immobilized on carbon nanotube modified electrodes. The amperometric detection using the bi-enzyme platform was realized through a series of cascade reactions that terminate in an electrochemical reduction reaction. Electrochemical measurements revealed that the sensitivity of the bi-enzyme sensor was 30.6±2.7µAcm(-2)µM(-1) and the limit of detection and limit of quantification were 13nM (1.80ppb) and 39nM (5.39ppb) respectively. Interference studies showed no significant interference from the other common plant volatile compounds. Synthetic analyte studies revealed that the bi-enzyme based biosensor can be used to reliably detect methyl salicylate released by unhealthy plants. Copyright © 2016. Published by Elsevier B.V.

Preparation of iron-deposited graphite surface for application as cathode material during electrochemical vat-dyeing process

International Nuclear Information System (INIS)

Anbu Kulandainathan, M.; Kiruthika, K.; Christopher, G.; Babu, K. Firoz; Muthukumaran, A.; Noel, M.

2008-01-01

Iron-deposited graphite surfaces were prepared, characterized and employed as cathode materials for electrochemical vat-dyeing process containing very low concentration of sodium dithionite. The electrodeposition, in presence of ammonium thiocyanate and gelatin or animal glue as binding additives, were found to give finer iron deposits for improved electrochemical dyeing application. The electrodeposits were characterized using scanning electron microscopy, electron-dispersive X-ray spectroscopy and X-ray diffraction methods, before and after electrochemical dyeing process. The electrochemical activity of the iron-deposited graphite electrodes always stored in water seems to depend on the surface-bound Fe 3+ /Fe 2+ redox species. Vat dyes like C.I. Vat Violet 1, C.I. Vat Green 1 and C.I. Vat Blue 4 could be efficiently dyed employing these above electrode materials. The colour intensity and washing fastness of the dyed fabrics were found to be equal with conventionally dyed fabrics. The electrodes could also be reused for the dyeing process

From electrochemical biosensors to biomimetic sensors based on molecularly imprinted polymers in environmental determination of heavy metals

Science.gov (United States)

Malitesta, Cosimino; Di Masi, Sabrina; Mazzotta, Elisabetta

2017-07-01

Recent work relevant to heavy metal determination by inhibition-enzyme electrochemical biosensors and by selected biomimetic sensors based on molecularly imprinted polymers has been reviewed. General features and peculiar aspects have been evidenced. The replace of biological component by artificial receptors promises higher selectivity and stability, while biosensors keep their capability of producing an integrated response directly related to toxicity of the samples.

Imprinted sol-gel electrochemical sensor for the determination of benzylpenicillin based on Fe3O4/SiO2 multi-walled carbon nanotubes-chitosans nanocomposite film modified carbon electrode

International Nuclear Information System (INIS)

Hu Yufang; Li Jiaxing; Zhang Zhaohui; Zhang Huabin; Luo Lijuan; Yao Shouzhuo

2011-01-01

Graphical abstract: A novel imprinted sol-gel electrochemical sensor based on Fe 3 O 4 /SiO 2 -MWNTs-CTS nanocomposite film and a thin MIP film has been developed on a carbon electrode. Highlights: → A novel imprinted sol-gel electrochemical sensor based on Fe 3 O 4 /SiO 2 -MWNTs-CTS nanocomposites has been developed. → Fe 3 O 4 /SiO 2 -MWNTs-CTS nanocomposites act as 'electronic wires' to enhance the electron transfer. → The inherent specificity of the MIPs brings about highly selectivity. The imprinted sensor detects benzylpenicillin in real samples successfully. - Abstract: Herein, a novel imprinted sol-gel electrochemical sensor based on multi-walled carbon nanotubes (MWNTs) doped with chitosan film on a carbon electrode has been developed. Prior to doped, the MWNTs have been decorated with Fe 3 O 4 nanoparticles which have been coated uniformly with SiO 2 layer. The characterization of imprinted sensor has been carried out by X-ray diffraction and scanning electron microscopy. The performance of the proposed imprinted sensor has been investigated using cyclic voltammetry and differential pulse voltammetry. The imprinted sensor offers a fast response and sensitive benzylpenicillin quantification. The fabricated benzylpenicillin imprinted sensor exhibits a linear response from 5.0 x 10 -8 to 1.0 x 10 -3 mol L -1 with a detection limit of 1.5 x 10 -9 mol L -1 . For samples analysis, perfect recoveries of the imprinted sensor for benzylpenicillin indicated that the imprinted sensor was able to detect benzylpenicillin in real samples successfully.

Iridium Oxide-reduced Graphene Oxide Nanohybrid Thin Film Modified Screen-printed Electrodes as Disposable Electrochemical Paper Microfluidic pH Sensors.

Science.gov (United States)

Yang, Jiang; Kwak, Tae-Joon; Zhang, Xiaodong; McClain, Robert; Chang, Woo-Jin; Gunasekaran, Sundaram

2016-11-22

A facile, controllable, inexpensive and green electrochemical synthesis of IrO2-graphene nanohybrid thin films is developed to fabricate an easy-to-use integrated paper microfluidic electrochemical pH sensor for resource-limited settings. Taking advantages from both pH meters and strips, the pH sensing platform is composed of hydrophobic barrier-patterned paper micropad (µPAD) using polydimethylsiloxane (PDMS), screen-printed electrode (SPE) modified with IrO2-graphene films and molded acrylonitrile butadiene styrene (ABS) plastic holder. Repetitive cathodic potential cycling was employed for graphene oxide (GO) reduction which can completely remove electrochemically unstable oxygenated groups and generate a 2D defect-free homogeneous graphene thin film with excellent stability and electronic properties. A uniform and smooth IrO2 film in nanoscale grain size is anodically electrodeposited onto the graphene film, without any observable cracks. The resulting IrO2-RGO electrode showed slightly super-Nernstian responses from pH 2-12 in Britton-Robinson (B-R) buffers with good linearity, small hysteresis, low response time and reproducibility in different buffers, as well as low sensitivities to different interfering ionic species and dissolved oxygen. A simple portable digital pH meter is fabricated, whose signal is measured with a multimeter, using high input-impedance operational amplifier and consumer batteries. The pH values measured with the portable electrochemical paper-microfluidic pH sensors were consistent with those measured using a commercial laboratory pH meter with a glass electrode.

Preparation of RuO2-TiO2/Nano-graphite composite anode for electrochemical degradation of ceftriaxone sodium.

Science.gov (United States)

Li, Dong; Guo, Xiaolei; Song, Haoran; Sun, Tianyi; Wan, Jiafeng

2018-06-05

Graphite-like material is widely used for preparing various electrodes for wastewater treatment. To enhance the electrochemical degradation efficiency of Nano-graphite (Nano-G) anode, RuO 2 -TiO 2 /Nano-G composite anode was prepared through the sol-gel method and hot-press technology. RuO 2 -TiO 2 /Nano-G composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and N 2 adsorption-desorption. Results showed that RuO 2 , TiO 2 and Nano-G were composited successfully, and RuO 2 and TiO 2 nanoparticles were distributed uniformly on the surface of Nano-G sheet. Specific surface area of RuO 2 -TiO 2 /Nano-G composite was higher than that of TiO 2 /Nano-G composite and Nano-G. Electrochemical performances of RuO 2 -TiO 2 /Nano-G anode were investigated by cyclic voltammetry, electrochemical impedance spectroscopy. RuO 2 -TiO 2 /Nano-G anode was applied to electrochemical degradation of ceftriaxone. The generation of hydroxyl radical (OH) was measured. Results demonstrated that RuO 2 -TiO 2 /Nano-G anode displayed enhanced electrochemical degradation efficiency towards ceftriaxone and yield of OH, which is derived from the synergetic effect between RuO 2 , TiO 2 and Nano-G, which enhance the specific surface area, improve the electrochemical oxidation activity and lower the charge transfer resistance. Besides, the possible degradation intermediates and pathways of ceftriaxone sodium were identified. This study may provide a viable and promising prospect for RuO 2 -TiO 2 /Nano-G anode towards effective electrochemical degradation of antibiotics from wastewater. Copyright © 2018 Elsevier B.V. All rights reserved.

eSensor: an electrochemical detection-based DNA microarray technology enabling sample-to-answer molecular diagnostics

Science.gov (United States)

Liu, Robin H.; Longiaru, Mathew

2009-05-01

DNA microarrays are becoming a widespread tool used in life science and drug screening due to its many benefits of miniaturization and integration. Microarrays permit a highly multiplexed DNA analysis. Recently, the development of new detection methods and simplified methodologies has rapidly expanded the use of microarray technologies from predominantly gene expression analysis into the arena of diagnostics. Osmetech's eSensor® is an electrochemical detection platform based on a low-to- medium density DNA hybridization array on a cost-effective printed circuit board substrate. eSensor® has been cleared by FDA for Warfarin sensitivity test and Cystic Fibrosis Carrier Detection. Other genetic-based diagnostic and infectious disease detection tests are under development. The eSensor® platform eliminates the need for an expensive laser-based optical system and fluorescent reagents. It allows one to perform hybridization and detection in a single and small instrument without any fluidic processing and handling. Furthermore, the eSensor® platform is readily adaptable to on-chip sample-to-answer genetic analyses using microfluidics technology. The eSensor® platform provides a cost-effective solution to direct sample-to-answer genetic analysis, and thus have a potential impact in the fields of point-of-care genetic analysis, environmental testing, and biological warfare agent detection.

Photo-induced electrochemical anodization of p-type silicon: achievement and demonstration of long term surface stability

International Nuclear Information System (INIS)

Dhanekar, Saakshi; Islam, S S; Harsh

2012-01-01

Surface stability is achieved and demonstrated by porous silicon (PS) fabricated using a wavelength-dependent photo-electrochemical (PEC) anodization technique. During anodization, the photon flux for all wavelengths was kept constant while only the effect of light wavelength on the surface morphology of PS was investigated. PS optical sensors were realized, characterized and tested using a photoluminescence (PL) quenching technique. An aliphatic chain of alcohols (methanol to n-octanol) was detected in the range of 10–200 ppm. Long term surface stability was observed from samples prepared under red (750–620 nm) and green illumination (570–495 nm), where the PL quenching cycles evoke the possibility of using PS for stable sensor device applications. This study provides a route for preparing highly sensitive organic vapour sensors with a precise selection of the fabrication parameters and demonstrating their prolonged performance. (paper)

A facile electrochemical intercalation and microwave assisted exfoliation methodology applied to screen-printed electrochemical-based sensing platforms to impart improved electroanalytical outputs.

Science.gov (United States)

Pierini, Gastón D; Foster, Christopher W; Rowley-Neale, Samuel J; Fernández, Héctor; Banks, Craig E

2018-06-12

Screen-printed electrodes (SPEs) are ubiquitous with the field of electrochemistry allowing researchers to translate sensors from the laboratory to the field. In this paper, we report an electrochemically driven intercalation process where an electrochemical reaction uses an electrolyte as a conductive medium as well as the intercalation source, which is followed by exfoliation and heating/drying via microwave irradiation, and applied to the working electrode of screen-printed electrodes/sensors (termed EDI-SPEs) for the first time. This novel methodology results in an increase of up to 85% of the sensor area (electrochemically active surface area, as evaluated using an outer-sphere redox probe). Upon further investigation, it is found that an increase in the electroactive area of the EDI-screen-printed based electrochemical sensing platforms is critically dependent upon the analyte and its associated electrochemical mechanism (i.e. adsorption vs. diffusion). Proof-of-concept for the electrochemical sensing of capsaicin, a measure of the hotness of chillies and chilli sauce, within both model aqueous solutions and a real sample (Tabasco sauce) is demonstrated in which the electroanalytical sensitivity (a plot of signal vs. concentration) is doubled when utilising EDI-SPEs over that of SPEs.

An Oxidase-Based Electrochemical Fluidic Sensor with High-Sensitivity and Low-Interference by On-Chip Oxygen Manipulation

Directory of Open Access Journals (Sweden)

Chang-Soo Kim

2012-06-01

Full Text Available Utilizing a simple fluidic structure, we demonstrate the improved performance of oxidase-based enzymatic biosensors. Electrolysis of water is utilized to generate bubbles to manipulate the oxygen microenvironment close to the biosensor in a fluidic channel. For the proper enzyme reactions to occur, a simple mechanical procedure of manipulating bubbles was developed to maximize the oxygen level while minimizing the pH change after electrolysis. The sensors show improved sensitivities based on the oxygen dependency of enzyme reaction. In addition, this oxygen-rich operation minimizes the ratio of electrochemical interference signal by ascorbic acid during sensor operation (i.e., amperometric detection of hydrogen peroxide. Although creatinine sensors have been used as the model system in this study, this method is applicable to many other biosensors that can use oxidase enzymes (e.g., glucose, alcohol, phenol, etc. to implement a viable component for in-line fluidic sensor systems.

Low temperature preparation of Ag-doped ZnO nanowire arrays for sensor and light-emitting diode applications

Science.gov (United States)

Lupan, O.; Viana, B.; Cretu, V.; Postica, V.; Adelung, R.; Pauporté, T.

2016-02-01

Transition metal doped-oxide semiconductor nanostructures are important to achieve enhanced and new properties for advanced applications. We describe the low temperature preparation of ZnO:Ag nanowire/nanorod (NW/NR) arrays by electrodeposition at 90 °C. The NWs have been characterized by SEM, EDX, transmittance and photoluminescence (PL) measurements. The integration of Ag in the crystal is shown. Single nanowire/nanorod of ZnO:Ag was integrated in a nanosensor structure leading to new and enhanced properties. The ultraviolet (UV) response of the nanosensor was investigated at room temperature. Experimental results indicate that ZnO:Ag (0.75 μM) nanosensor possesses faster response/recovery time and better response to UV light than those reported in literature. The sensor structure has been also shown to give a fast response for the hydrogen detection with improved performances compared to pristine ZnO NWs. ZnO:Ag nanowire/nanorod arrays electrochemically grown on p-type GaN single crystal layer is also shown to act as light emitter in LED structures. The emission wavelength is red-shifted compared to pristine ZnO NW array. At low Ag concentration a single UV-blue emission is found whereas at higher concentration of dopant the emission is broadened and extends up to the red wavelength range. Our study indicates that high quality ZnO:Ag NW/NR prepared at low temperature by electrodeposition can serve as building nanomaterials for new sensors and light emitting diodes (LEDs) structures with low-power consumption.

An electrochemical sensor for warfarin determination based on covalent immobilization of quantum dots onto carboxylated multiwalled carbon nanotubes and chitosan composite film modified electrode

International Nuclear Information System (INIS)

Gholivand, Mohammad Bagher; Mohammadi-Behzad, Leila

2015-01-01

A method is described for the construction of a novel electrochemical warfarin sensor based on covalent immobilization of CdS-quantum dots (CdS-QDs) onto carboxylated multiwalled carbon nanotubes/chitosan (CS) composite film on the surface of a glassy carbon electrode. The CdS-QDs/CS/MWCNTs were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, XRD analysis and electrochemical impedance spectroscopy (EIS). The sensor showed optimum anodic stripping response within 90 s at an accumulation potential of 0.75 V. The modified electrode was used to detect the concentration of warfarin with a wide linear range of 0.05–80 μM and a detection limit (S/N = 3) of 8.5 nM. The proposed sensor has good storage stability, repeatability and reproducibility and was successfully applied for the determination of warfarin in real samples such as urine, serum and milk. - Highlights: • A new sensitive sensor for warfarin determination was developed. • The sensor was constructed based on covalent immobilization of CdS-QDs on the chitosan/MWCNTs/GCE. • The parameters affecting the stripping analysis of warfarin were optimized. • The proposed sensor is used for trace determination of warfarin in urine, serum and milk

An electrochemical sensor for warfarin determination based on covalent immobilization of quantum dots onto carboxylated multiwalled carbon nanotubes and chitosan composite film modified electrode

Energy Technology Data Exchange (ETDEWEB)

Gholivand, Mohammad Bagher, E-mail: mbgholivand2013@gmail.com; Mohammadi-Behzad, Leila

2015-12-01

A method is described for the construction of a novel electrochemical warfarin sensor based on covalent immobilization of CdS-quantum dots (CdS-QDs) onto carboxylated multiwalled carbon nanotubes/chitosan (CS) composite film on the surface of a glassy carbon electrode. The CdS-QDs/CS/MWCNTs were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, XRD analysis and electrochemical impedance spectroscopy (EIS). The sensor showed optimum anodic stripping response within 90 s at an accumulation potential of 0.75 V. The modified electrode was used to detect the concentration of warfarin with a wide linear range of 0.05–80 μM and a detection limit (S/N = 3) of 8.5 nM. The proposed sensor has good storage stability, repeatability and reproducibility and was successfully applied for the determination of warfarin in real samples such as urine, serum and milk. - Highlights: • A new sensitive sensor for warfarin determination was developed. • The sensor was constructed based on covalent immobilization of CdS-QDs on the chitosan/MWCNTs/GCE. • The parameters affecting the stripping analysis of warfarin were optimized. • The proposed sensor is used for trace determination of warfarin in urine, serum and milk.

Construction of a zinc porphyrin-fullerene-derivative based nonenzymatic electrochemical sensor for sensitive sensing of hydrogen peroxide and nitrite.

Science.gov (United States)

Wu, Hai; Fan, Suhua; Jin, Xiaoyan; Zhang, Hong; Chen, Hong; Dai, Zong; Zou, Xiaoyong

2014-07-01

Enzymatic sensors possess high selectivity but suffer from some limitations such as instability, complicated modified procedure, and critical environmental factors, which stimulate the development of more sensitive and stable nonenzymatic electrochemical sensors. Herein, a novel nonenzymatic electrochemical sensor is proposed based on a new zinc porphyrin-fullerene (C60) derivative (ZnP-C60), which was designed and synthesized according to the conformational calculations and the electronic structures of two typical ZnP-C60 derivatives of para-ZnP-C60 (ZnP(p)-C60) and ortho-ZnP-C60 (ZnP(o)-C60). The two derivatives were first investigated by density functional theory (DFT) and ZnP(p)-C60 with a bent conformation was verified to possess a smaller energy gap and better electron-transport ability. Then ZnP(p)-C60 was entrapped in tetraoctylammonium bromide (TOAB) film and modified on glassy carbon electrode (TOAB/ZnP(p)-C60/GCE). The TOAB/ZnP(p)-C60/GCE showed four well-defined quasi-reversible redox couples with extremely fast direct electron transfer and excellent nonenzymatic sensing ability. The electrocatalytic reduction of H2O2 showed a wide linear range from 0.035 to 3.40 mM, with a high sensitivity of 215.6 μA mM(-1) and a limit of detection (LOD) as low as 0.81 μM. The electrocatalytic oxidation of nitrite showed a linear range from 2.0 μM to 0.164 mM, with a sensitivity of 249.9 μA mM(-1) and a LOD down to 1.44 μM. Moreover, the TOAB/ZnP(p)-C60/GCE showed excellent stability and reproducibility, and good testing recoveries for analysis of the nitrite levels of river water and rainwater. The ZnP(p)-C60 can be used as a novel material for the fabrication of nonenzymatic electrochemical sensors.

Electrochemical sensor for dopamine based on a novel graphene-molecular imprinted polymers composite recognition element

DEFF Research Database (Denmark)

Mao, Yan; Bao, Yu; Gan, Shiyu

2011-01-01

A novel composite of graphene sheets/Congo red-molecular imprinted polymers (GSCR-MIPs) was synthesized through free radical polymerization (FRP) and applied as a molecular recognition element to construct dopamine (DA) electrochemical sensor. The template molecules (DA) were firstly absorbed...... at the GSCR surface due to their excellent affinity, and subsequently, selective copolymerization of methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) was further achieved at the GSCR surface. Potential scanning was presented to extract DA molecules from the imprinted polymers film...

From Electrochemical Biosensors to Biomimetic Sensors Based on Molecularly Imprinted Polymers in Environmental Determination of Heavy Metals

Directory of Open Access Journals (Sweden)

Cosimino Malitesta

2017-07-01

Full Text Available Recent work relevant to heavy metal determination by inhibition-enzyme electrochemical biosensors and by selected biomimetic sensors based on molecularly imprinted polymers has been reviewed. General features and peculiar aspects have been evidenced. The replace of biological component by artificial receptors promises higher selectivity and stability, while biosensors keep their capability of producing an integrated response directly related to biological toxicity of the samples.

Preparation of Graphene Sheets by Electrochemical Exfoliation of Graphite in Confined Space and Their Application in Transparent Conductive Films.

Science.gov (United States)

Wang, Hui; Wei, Can; Zhu, Kaiyi; Zhang, Yu; Gong, Chunhong; Guo, Jianhui; Zhang, Jiwei; Yu, Laigui; Zhang, Jingwei

2017-10-04

A novel electrochemical exfoliation mode was established to prepare graphene sheets efficiently with potential applications in transparent conductive films. The graphite electrode was coated with paraffin to keep the electrochemical exfoliation in confined space in the presence of concentrated sodium hydroxide as the electrolyte, yielding ∼100% low-defect (the D band to G band intensity ratio, I D /I G = 0.26) graphene sheets. Furthermore, ozone was first detected with ozone test strips, and the effect of ozone on the exfoliation of graphite foil and the microstructure of the as-prepared graphene sheets was investigated. Findings indicate that upon applying a low voltage (3 V) on the graphite foil partially coated with paraffin wax that the coating can prevent the insufficiently intercalated graphite sheets from prematurely peeling off from the graphite electrode thereby affording few-layer (graphene sheets in a yield of as much as 60%. Besides, the ozone generated during the electrochemical exfoliation process plays a crucial role in the exfoliation of graphite, and the amount of defect in the as-prepared graphene sheets is dependent on electrolytic potential and electrode distance. Moreover, the graphene-based transparent conductive films prepared by simple modified vacuum filtration exhibit an excellent transparency and a low sheet resistance after being treated with NH 4 NO 3 and annealing (∼1.21 kΩ/□ at ∼72.4% transmittance).

Application of commercial sensor manufacturing methods for NOx/NH3 mixed potential sensors for emissions control

Energy Technology Data Exchange (ETDEWEB)

Brosha, Eric L [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory; Nelson, Mark A [Los Alamos National Laboratory; Sekhar, Praveen [Los Alamos National Laboratory; Williamson, Todd [Los Alamos National Laboratory; Garzon, Fernando H [Los Alamos National Laboratory

2009-01-01

The purpose of this research effort is to develop a low cost on-board Nitrogen Oxide (NO{sub x})/Ammonia (NH{sub 3}) sensor that can not only be used for emissions control but has the potential to improve efficiency through better monitoring of the combustion process and feedback control in both vehicle and stationary systems. Over the past decade, Los AJamos National Laboratory (LANL) has developed a unique class of electrochemical gas sensors for the detection of carbon monoxide, hydrocarbons, hydrogen and nitrogen oxides. These sensors are based on the mixed-potential phenomenon and are a modification of the existing automotive lambda (oxygen) sensor and have the potential to meet the stringent sensitivity, selectivity and stability requirements of an on-board emissions/engine control sensor system. The current state of the art LANL technology is based on the stabilization of the electrochemical interfaces and relies on an externally heated, hand-made, tape cast device. We are now poised to apply our patented sensing principles in a mass production sensor platform that is more suitable for real world engine-out testing such as on dynamometers for vehicle applications and for exhaust-out testing in heavy boilers/SCR systems in power plants. In this present work, our goal is to advance towards commercialization of this technology by packaging the unique LANL sensor design in a standard automotive sensor-type platform. This work is being performed with the help of a leading US technical ceramics firm, utilizing commercial manufacturing techniques. Initial tape cast platforms with screen printed metal oxide and Pt sensor electrodes have shown promising results but also clearly show the need for us to optimize the electrode and electrolyte compositions/morphologies and interfaces of these devices in order to demonstrate a sensitive, selective, and stable NO{sub x} sensor. Our previous methods and routes to preparing stable and reproducible mixed potential sensors

An electrochemical sensor for gallic acid based on Fe{sub 2}O{sub 3}/electro-reduced graphene oxide composite: Estimation for the antioxidant capacity index of wines

Energy Technology Data Exchange (ETDEWEB)

Gao, Feng, E-mail: fgao1981@126.com [College of Chemistry and Environment, Fujian Province Key Laboratory of Morden Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China); Department of Chemistry, Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan); Zheng, Delun [College of Chemistry and Environment, Fujian Province Key Laboratory of Morden Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China); Tanaka, Hidekazu [Department of Chemistry, Graduate School of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan); Zhan, Fengping; Yuan, Xiaoning; Gao, Fei [College of Chemistry and Environment, Fujian Province Key Laboratory of Morden Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China); Wang, Qingxiang, E-mail: axiang236@126.com [College of Chemistry and Environment, Fujian Province Key Laboratory of Morden Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China)

2015-12-01

A highly sensitive electrochemical sensor for gallic acid (GA), an important polyphenolic compound, was fabricated using the hybrid material of chitosan (CS), fishbone-shaped Fe{sub 2}O{sub 3} (fFe{sub 2}O{sub 3}), and electrochemically reduced graphene oxide (ERGO) as the sensing matrix. The electrochemical characterization experiments showed that the CS–fFe{sub 2}O{sub 3}–ERGO modified glassy carbon electrode (CS–fFe{sub 2}O{sub 3}–ERGO/GCE) had large surface area, excellent electronic conductivity and high stability. The GA presented a superior electrochemical response on CS–fFe{sub 2}O{sub 3}–ERGO/GCE in comparison with the single-component modified electrode. The electrochemical mechanism and optimal test conditions of GA on the electrode surface were carefully investigated. Under the optimal conditions, the oxidation peak currents in differential pulse voltammetry (DPV) experiments exhibited a good linear relationship with the logarithmic values of GA concentration over the range from 1.0 × 10{sup −6} M to 1.0 × 10{sup −4} M. Based on signal-to-noise (S/N) characteristic of 3, the detection limit was estimated to be 1.5 × 10{sup −7} M. The proposed sensor has also been applied for estimating the antioxidant capacity index of real samples of red and white wines. - Highlights: • Fishbone-shaped Fe{sub 2}O{sub 3} (fFe{sub 2}O{sub 3}) nanoparticles were synthesized by a simple template-free solvothermal method. • The nanocomposite of fFe{sub 2}O{sub 3}, graphene and chitosan was used as the sensing platform for gallic acid. • The sensor shows a wide linear range and low detection limit for gallic acid. • The antioxidant capacity index of wines was successfully evaluated by the sensor.

Highly sensitive voltammetric sensor based on immobilization of bisphosphoramidate-derivative and quantum dots onto multi-walled carbon nanotubes modified gold electrode for the electrocatalytic determination of olanzapine

Energy Technology Data Exchange (ETDEWEB)

Mohammadi-Behzad, Leila [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Gholivand, Mohammad Bagher, E-mail: mbgholivand@yahoo.com [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Shamsipur, Mojtaba [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Gholivand, Khodayar [Department of Chemistry, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Barati, Ali [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Gholami, Akram [Department of Chemistry, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

2016-03-01

In the present paper, a new bisphosphoramidate derivative compound, 1, 4-bis(N-methyl)-benzene-bis(N-phenyl, N-benzoylphosphoramidate) (BMBPBP), was synthesized and used as a mediator for the electrocatalytic oxidation of olanzapine. The electro-oxidation of olanzapine at the surface of the BMBPBP/CdS-quantum dots/multi-walled carbon nanotubes (BMBPBP/CdS-QDs/MWCNTs) modified gold electrode was studied using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. This sensor showed an excellent electrocatalytic oxidation activity toward olanzapine at less positive potential, pronounced current response, and good sensitivity. The diffusion coefficient and kinetic parameters (such as electron transfer coefficient and the heterogeneous rate constant) were determined for olanzapine oxidation, using the electrochemical approaches. Surface morphology and electrochemical properties of the prepared modified electrode were investigated by scanning electron microscopy (SEM), cyclic voltammetry and electrochemical impedance spectroscopy techniques. The hydrodynamic amperometry at rotating modified electrode at constant potential versus reference electrode was used for detection of olanzapine. Under optimized conditions, the calibration plot was linear in the concentration range of 20 nM to 100 μM and detection limit was found to be 6 nM. The proposed method was successfully applied to the determination of olanzapine in pharmaceuticals and human serum samples. - Highlights: • A highly sensitive sensor for OLZ determination was developed. • The sensor constructed based on immobilization of BMBPBP on CdS-QDs/MWCNTs Au electrode • The morphology of the modified electrode was examined by SEM. • The prepared sensor shows stable electrochemical behavior at a wide pH range. • The proposed sensor is used for trace determination of OLZ in real samples.

Preparation of venlafaxine hydrochloride sustained-release tablets

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ZHANG Yang

2013-02-01

Full Text Available A novel non－enzymatic glucose sensor was developed by electrodepositing copper film onto the graphene(GR substrate.The morphologies and structures of the nanocomposites were characterized by field emission scanning electron microscope (FESEM.The electrochemical performances of the Cu/GR nanocomposite film were investigated.The Cu/GR nanocomposite film showed good electrocatalytic activity towards glucose oxidation in alkaline solution.The Cu/GR nanocomposite film-based sensor displayed a linear concentration range from 8×10-6 to 9.4×10-4 mol/L with the sensitivity of 0.225 A·L·mol-1 and the detection limit (S/N=3 of 2.5 μmol/L for the detection of glucose.With an enhanced electrocatalytic property,high sensitivity and good stability.The as-prepared sensor is promising for the future development of nonenzymatic sensors.

Preparation and characterization of poly(vinylidene fluoride) based composite electrolytes for electrochemical devices

International Nuclear Information System (INIS)

Karabelli, D.; Leprêtre, J.-C.; Cointeaux, L.; Sanchez, J.-Y.

2013-01-01

Highlights: • Macroporous PVdF based membranes for electrochemical applications were prepared with support materials. • Woven PET and PA fabrics and non-woven cellulose paper are used as support materials. • Porous structure of PVdF was obtained on the support material. • Interaction between the electrolyte solvent and the composite material played an important role on the mechanical properties. • Compared to the pure PVdF separators, enhanced mechanical strength was obtained for composite separators, without decreasing the ionic conductivity. -- Abstract: PVdF-based separators are very promising materials in electrochemical energy storage systems but they suffer from fairly poor mechanical properties. To overcome this drawback, composite PVdF separators were fabricated and characterized in electrolytes of Li-ion batteries and supercapacitors. Macroporous PVdF composite separators were prepared by phase inversion method using PA and PET, and non-woven cellulose as support layers. Ionic conductivity and thermomechanical analyses were performed using electrolytes of Li-ion batteries and supercapacitors. The composite approach allowed a tremendous increase of the mechanical performances of the separator (between 340 and 750 MPa) compared to the unreinforced PVdF separator (56 MPa), without compromising the ionic conductivities (up to 15.6 mS cm −1 )

Detection of Cu2+ in Water Based on Histidine-Gold Labeled Multiwalled Carbon Nanotube Electrochemical Sensor

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Rilong Zhu

2017-01-01

Full Text Available Based on the strong interaction between histidine and copper ions and the signal enhancement effect of gold-labeling carbon nanotubes, an electrochemical sensor is established and used to measure copper ions in river water. In this study the results show that the concentrations of copper ion have well linear relationship with the peak current in the range of 10−11–10−7 mol/L, and the limit of detection is 10−12 mol/L. When using this method to detect copper ions in the Xiangjiang River, the test results are consistent with the atomic absorption method. This study shows that the sensor is convenient to be used in daily monitoring of copper ions in river water.

Sensitive Determination of 6-Thioguanine Using Caffeic Acid-functionalized Fe3O4 Nanoparticles as an Electrochemical Sensor

Science.gov (United States)

Amir, Md.; Tunesi, Mawada M.; Soomro, Razium A.; Baykal, Abdülhadi; Kalwar, Nazar H.

2018-04-01

The study demonstrates the potential application of caffeic acid-functionalized magnetite nanoparticles (CA-Fe3O4 NPs) as an effective electrode modifying material for the electrochemical oxidation of the 6-thioguanine (6-TG) drug. The functionalized Fe3O4 NPs were prepared using simple wet-chemical methodology where the used caffeic acid acted simultaneously as growth controlling and functionalizing agent. The study discusses the influence of an effective functionalization on the signal sensitivity observed for the electro-oxidation of 6-TG over CA-Fe3O4 NPs in comparison to a glassy carbon electrode modified with bare and nicotinic acid (NA)-functionalized Fe3O4 NPs. The experiment results provided sufficient evidence to support the importance of favorable functionality to achieve higher signal sensitivity for the electro-oxidation of 6-TG. The presence of favorable interactions between the active functional moieties of caffeic acid and 6-TG synergized with the greater surface area of magnetic NPs produces a stable electro-oxidation signal within the working range of 0.01-0.23 μM with sensitive up to 0.001 μM. Additionally, the sensor showed the strong anti-interference potential against the common co-existing drug molecules such as benzoic acid, acetaminophen, epinephrine, norepinephrine, glucose, ascorbic acid and l-cysteine. In addition, the successful quantification of 6-TG from the commercial tablets obtained from local pharmacy further signified the practical capability of the discussed sensor.

Modification of glassy carbon electrode with poly(hydroxynaphthol blue)/multi-walled carbon nanotubes composite and construction a new voltammetric sensor for the simultaneous determination of hydroquinone, catechol, and resorcinol

Science.gov (United States)

Daneshinejad, Hassan; Arab Chamjangali, Mansour; Goudarzi, Nasser; Hossain Amin, Amir

2018-03-01

A novel voltammetric sensor is developed based on a poly(hydroxynaphthol blue)/multi-walled carbon nanotubes-modified glassy carbon electrode for the simultaneous determination of the dihydroxybenzene isomers hydroquinone (HQ), catechol (CC), and resorcinol (RS). The preparation and basic electrochemical performance of the sensor are investigated in details. The electrochemical behavior of the dihydroxybenzene isomers at the sensor is studied by the cyclic and differential pulse voltammetric techniques. The results obtained show that this new electrochemical sensor exhibits an excellent electro-catalytic activity towards oxidation of the three isomers. The mechanism of this electro-catalytic activity is discussed. Using the optimum parameters, limit of detection obtained 0.24, 0.24, and 0.26 μmol L-1 for HQ, CC, and RS, respectively. The modified electrode is also successfully applied to the simultaneous determination of dihydroxybenzene in water samples.

Alizarin red S functionalized mesoporous silica modified glassy carbon electrode for electrochemical determination of anthracene

International Nuclear Information System (INIS)

Liu, Shan; Wei, Maochao; Zheng, Xiangli; Xu, Shuai; Xia, Fangquan; Zhou, Changli

2015-01-01

Highlights: • Alizarin red S-SBA15 composite was prepared and characterized. • A novel sensing platform was constructed for anthracene determination. • The proposed sensor exhibited high sensitivity and low detection limit for detecting anthracene. • This method can be applied to the practical detection of anthracene in waste water. - Abstract: In the paper, a novel and sensitive electrochemical sensor based on modification of electroactive alizarin red S functionalized mesoporous silica material SBA15 onto glassy carbon electrode (ARS-SBA15/GCE) was developed. Alizarin red S, called electrochemical probe that can selectively recognize polycyclic aromatic hydrocarbons (PAHs), as tools for the detection of tricyclic aromatic hydrocarbon anthracene. The morphology and interface property of ARS modified SBA15 (ARS-SBA15) were examined by transmission electron microscopy (TEM) and fourier transform infrared spectroscopy (FTIR). Taking advantage of the π-π stacking force between alizarin red S and anthracene, the ARS-SBA15/GCE sensor could detect anthracene quantitatively in a wide range of 1.0 pM–10.0 nM and a low detection limit of 0.5 pM (S/N = 3). Other PAHs, such as naphthalene, phenanthrene, pyrene, and benzo[a]pyrene show little interference on the detection. Consequently, a simple and sensitive electrochemical method was proposed for the determination of anthracene, which can be used to determine anthracene in waste water samples. The electrochemical method provides a general tool that complements the commonly used spectroscopic methods and immune method for the detection of PAHs

Robust high temperature oxygen sensor electrodes

DEFF Research Database (Denmark)

Lund, Anders

Platinum is the most widely used material in high temperature oxygen sensor electrodes. However, platinum is expensive and the platinum electrode may, under certain conditions, suffer from poisoning, which is detrimental for an oxygen sensor. The objective of this thesis is to evaluate electrode...... materials as candidates for robust oxygen sensor electrodes. The present work focuses on characterising the electrochemical properties of a few electrode materials to understand which oxygen electrode processes are limiting for the response time of the sensor electrode. Three types of porous platinum......-Dansensor. The electrochemical properties of the electrodes were characterised by electrochemical impedance spectroscopy (EIS), and the structures were characterised by x-ray diffraction and electron microscopy. At an oxygen partial pressures of 0.2 bar, the response time of the sensor electrode was determined by oxygen...

The pharmacokinetic study of rutin in rat plasma based on an electrochemically reduced graphene oxide modified sensor

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Pei Zhang

2016-04-01

Full Text Available An electrochemical method based on a directly electrochemically reduced graphene oxide (ERGO film coated on a glassy carbon electrode (GCE was developed for the rapid and convenient determination of rutin in plasma. ERGO was modified on the surface of GCE by one-step electro-deposition method. Electrochemical behavior of rutin on ERGO/GCE indicated that rutin underwent a surface-controlled quasi-reversible process and the electrochemical parameters such as charge transfer coefficient (α, electron transfer number (n and electrode reaction standard rate constant (ks were 0.53, 2 and 3.4 s−1, respectively. The electrochemical sensor for rutin in plasma provided a wide linear response range of 4.70×10−7−1.25×10−5 M with the detection limit (s/n=3 of 1.84×10−8 M. The assay was successfully used to the pharmacokinetic study of rutin. The pharmacokinetic parameters such as elimination rate half-life (t1/2, area under curve (AUC, and plasma clearance (CL were calculated to be 3.345±0.647 min, 5750±656.0 µg min/mL, and 5.891±0.458 mL/min/kg, respectively. The proposed method utilized a small sample volume of 10 μL and had no complicated sample pretreatment (without deproteinization, which was simple, eco-friendly, and time- and cost-efficient for rutin pharmacokinetic studies.

Electrochemical dopamine sensor based on P-doped graphene: Highly active metal-free catalyst and metal catalyst support.

Science.gov (United States)

Chu, Ke; Wang, Fan; Zhao, Xiao-Lin; Wang, Xin-Wei; Tian, Ye

2017-12-01

Heteroatom doping is an effective strategy to enhance the catalytic activity of graphene and its hybrid materials. Despite a growing interest of P-doped graphene (P-G) in energy storage/generation applications, P-G has rarely been investigated for electrochemical sensing. Herein, we reported the employment of P-G as both metal-free catalyst and metal catalyst support for electrochemical detection of dopamine (DA). As a metal-free catalyst, P-G exhibited prominent DA sensing performances due to the important role of P doping in improving the electrocatalytic activity of graphene toward DA oxidation. Furthermore, P-G could be an efficient supporting material for loading Au nanoparticles, and resulting Au/P-G hybrid showed a dramatically enhanced electrocatalytic activity and extraordinary sensing performances with a wide linear range of 0.1-180μM and a low detection limit of 0.002μM. All these results demonstrated that P-G might be a very promising electrode material for electrochemical sensor applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Ultrasensitive and simultaneous detection of hydroquinone, catechol and resorcinol based on the electrochemical co-reduction prepared Au-Pd nanoflower/reduced graphene oxide nanocomposite

International Nuclear Information System (INIS)

Chen, Yuan; Liu, Xiaoying; Zhang, Si; Yang, Liuqing; Liu, Meiling; Zhang, Youyu; Yao, Shouzhuo

2017-01-01

A simple and efficient eletrochemical sensing platform for simultaneous detection of hydroquinone (HQ), catechol (CC) and resorcinol (RC) based on the Au-Pd bimetallic and graphene is described in this paper. The Au-Pd reduced graphene oxide (Au-Pd NF/rGO) was prepared by the electrochemical co-reduction deposition via cyclic voltammetry method (CV). The Au-Pd NF/rGO nanocomposite was examined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and electrochemical methods CV and differential pulse voltammety (DPV) study showed that the three dihydroxybenzene isomers can be catalytically oxidized and discriminated simultaneously on the Au-Pd NF/rGO/GCE. The presence of Pd makes the performance of the sensor superior to that of in the absence of it. Owing to the integrated superior conductivity and excellent catalytic property of Au-Pd NF/rGO, the sensitive and simultaneous detection of HQ, CC and RC was realized in the individual or triple-components solution based on the as proposed Au-Pd NF/rGO/GCE, which shows wide linear range and low detection limit. The detection of them in tap water, river water and lake water were also successfully performed and good recovery was obtained.

Sample preparation and electrochemical data of Co3O4 working electrode for seawater splitting

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Malkeshkumar Patel

2017-10-01

Full Text Available In this data article, we presented the electrochemical data of the working electrode made of Co3O4 semi-transparent film. Electrochemically stable, porous nature of Kirkendall-diffusion grown Co3O4 films were applied to generate hydrogen from the seawater splitting (Patel et al., 2017 [1]. The data presented in this article includes the photograph of prepared samples, polarization curves for water oxidation and Tafel plot, linear sweep voltammetry measurements under the pulsed light condition in 0.1 M Na2S2O3 electrolyte, and transient photoresponses with natural sea water. Moreover, seawater splitting using the Co3O4 working electrode is demonstrated.

One pot synthesis of dandelion-like polyaniline coated gold nanoparticles composites for electrochemical sensing applications.

Science.gov (United States)

Lu, Zhiwei; Dai, Wanlin; Liu, Baichen; Mo, Guangquan; Zhang, Junjun; Ye, Jiaping; Ye, Jianshan

2018-04-18

In this work, we report a facile and green strategy for one pot and in-situ synthesis of a dandelion-like conductive polyaniline coated gold nanoparticle nanocomposites (Au@PANI). The Au@PANI was characterized by SEM, TEM, XRD, TGA, FTIR, UV-vis and conductivity measurement, respectively. Newly-designed Au@PANI materials possessed a significantly high conductivity and strong adsorption capability. Thus, the Au@PANI modified glassy carbon electrode (GCE) was utilized for construct a novel electrochemical sensor for the simultaneous assay of Pb 2+ and Cu 2+ using square wave anodic stripping voltammetry (SWASV). Under the optimized conditions, an excellent electrochemical response in the simultaneous of Pb 2+ and Cu 2+ with detection limit of 0.003 and 0.008 μM (S/N = 3), respectively. Moreover, the prepared sensors realized an excellent reproducibility, repeatability and long term stability, as well as reliable practical assays in real water samples. Besides, the possible formation mechanism and sensing mechanism of Au@PANI nanocomposites have been discussed in detail. We believe this study provides a novel method of fabrication of noble metal nanoparticles decorated conducting polymer materials for the electrochemical sensing applications. Copyright © 2018 Elsevier Inc. All rights reserved.

Fabrication of an electrochemical sensor for determination of doxorubicin in human plasma and its interaction with DNA

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Reza Hajian

2017-02-01

Full Text Available In this work, an electrochemical sensor was fabricated for determination of an anthracycline, doxorubicin (DOX as a chemotherapy drug in plasma based on multi-walled carbon nanotubes modified platinum electrode (Pt/MWCNTs. DOX was effectively accumulated on the surface of modified electrode and generated a pair of redox peaks at around 0.522 and 0.647 V (vs. Ag/AgCl in Britton Robinson (B-R buffer (pH 4.0, 0.1 M. The electrochemical parameters including pH, type of buffer, accumulation time, amount of modifier and scan rate were optimized. Under the optimized conditions, there was a linear correlation between cathodic peak current and concentration of DOX in the range of 0.05–4.0 µg/mL with the detection limit of 0.002 µg/mL. The number of electron transfers (n and electron transfer-coefficient (α were estimated as 2.0 and 0.25, respectively. The constructed sensor displayed excellent precision, sensitivity, repeatability and selectivity in the determination of doxorubicin in plasma. Moreover, cyclic voltammetry studies of DOX in the presence of DNA showed an intercalation mechanism with binding constant (Kb of 1.12×105 L/mol.

Evaluation of Aquatic Environments Using a Sensorial System Based on Conducting Polymers and its Potential Application in Electrochemical Sensors

Directory of Open Access Journals (Sweden)

Nelson Consolin Filho

2008-06-01

Full Text Available A sensor array consisted of interdigitated gold electrodes modified with nanostructured ultra-thin films of conducting polymers was used to evaluate different water samples from three distinct reservoirs, located in the São Paulo State, Brazil, according to their eutrophic level, i.e. oligotrophic, eutrophic and hypereutrophic. These reservoirs samples presented different eutrophic levels. The sensor array data were processed and analyzed by using PCA (principal component analysis. In the near future, this will be a reliable and straightforward method to analyze water samples based on the concept of global selectivity and electrochemical impedance.

Facile preparation of self-healing superhydrophobic CeO2 surface by electrochemical processes

Science.gov (United States)

Nakayama, Katsutoshi; Hiraga, Takuya; Zhu, Chunyu; Tsuji, Etsushi; Aoki, Yoshitaka; Habazaki, Hiroki

2017-11-01

Herein we report simple electrochemical processes to fabricate a self-healing superhydrophobic CeO2 coating on Type 304 stainless steel. The CeO2 surface anodically deposited on flat stainless steel surface is hydrophilic, although high temperature-sintered and sputter-deposited CeO2 surface was reported to be hydrophobic. The anodically deposited hydrophilic CeO2 surface is transformed to hydrophobic during air exposure. Specific accumulation of contaminant hydrocarbon on the CeO2 surface is responsible for the transformation to hydrophobic state. The deposition of CeO2 on hierarchically rough stainless steel surface produces superhydrophobic CeO2 surface, which also shows self-healing ability; the surface changes to superhydrophilic after oxygen plasma treatment but superhydrophobic state is recovered repeatedly by air exposure. This work provides a facile method for preparing a self-healing superhydrophobic surface using practical electrochemical processes.

ELECTROCHEMICAL SYNTHEZIS AND CHARACTERIZATION OF POLYPYRROLE FOR DODECYLSULFATE SENSOR MEMBRANE

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Abdul Haris Watoni

2010-06-01

Full Text Available A conducting polymer, polypyrrole, has been electrochemically synthesized from pyrrole monomer using cyclic voltammetry technique in aqueous solution in the presence of HDS dopant and KNO3 supporting electrolyte. The polymer was deposited on the surface of an Au-wire and the modified electrode obtained was then used as dodecylsulfate (DS- ion sensor electrode. The best performance PPy-DS modified-Au electrode conditioned in the air system without HDS or SDS solution gave linear potential response for the concentration range of 1.0 x 10-5 - 1.0 x 10-3 M, sensitivity of 54.5 mV/decade, detection limit of 1.0 x 10-5 M, and response time of 23 - 30 second.  The electrode showed good selectivity towards other anions, therefore can be used to determine SDS concentration in real samples system without any change of the samples matrix.   Keywords: polypyrrole, SDS, cyclic voltammetry

Electrochemical preparation of hematite nanostructured films for solar hydrogen production

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Ebadzadeh T.

2012-10-01

Full Text Available Photoelectrochemical water splitting is a clean and promising technique for using a renewable source of energy, i.e., solar energy, to produce hydrogen. In this work electrochemical formation of iron oxyhydroxide and its conversion to hematite (α- Fe2O3 through thermal treatment have been studied. Oxyhydroxide iron compounds have been prepared onto SnO2/F covered glass substrate by potential cycling with two different potential sweep rate values; then calcined at 520 °C in air to obtain α-Fe2O3 nanostrutured films for their implementation as photoanode in a photoelectrochemical cell. X-ray diffraction analysis allowed finding that iron oxides films have nanocrystalline character. Scanning electron microscopy revealed that films have nanostructured morphology. The obtained results are discussed considering the influence of potential sweep rate employed during the preparation of iron oxyhydroxide film on optical, structural and morphological properties of hematite nanostructured films. Results show that films have acceptable characteristics as photoanode in a photoelectrochemical cell for hydrogen generation from water.

Tape-cast sensors and method of making

Science.gov (United States)

Mukundan, Rangachary [Santa Fe, NM; Brosha, Eric L [Los Alamos, NM; Garzon, Fernando H [Santa Fe, NM

2009-08-18

A method of making electrochemical sensors in which an electrolyte material is cast into a tape. Prefabricated electrodes are then partially embedded between two wet layers of the electrolyte tape to form a green sensor, and the green sensor is then heated to sinter the electrolyte tape around the electrodes. The resulting sensors can be used in applications such as, but not limited to, combustion control, environmental monitoring, and explosive detection. A electrochemical sensor formed by the tape-casting method is also disclosed.

Hydrogen peroxide sensor: Uniformly decorated silver nanoparticles on polypyrrole for wide detection range

International Nuclear Information System (INIS)

Nia, Pooria Moozarm; Meng, Woi Pei; Alias, Y.

2015-01-01

Graphical abstract: - Highlights: • Electrochemical method was used for depositing silver nanoparticles and polypyrrole. • Silver nanoparticles (25 nm) were uniformly decorated on electrodeposited polypyrrole. • (Ag(NH 3 ) 2 OH) precursor showed better electrochemical performance than (AgNO 3 ). • The sensor showed superior performance toward H 2 O 2 . - Abstract: Electrochemically synthesized polypyrrole (PPy) decorated with silver nanoparticles (AgNPs) was prepared and used as a nonenzymatic sensor for hydrogen peroxide (H 2 O 2 ) detection. Polypyrrole was fabricated through electrodeposition, while silver nanoparticles were deposited on polypyrrole by the same technique. The field emission scanning electron microscopy (FESEM) images showed that the electrodeposited AgNPs were aligned along the PPy uniformly and the mean particle size of AgNPs is around 25 nm. The electrocatalytic activity of AgNPs-PPy-GCE toward H 2 O 2 was studied using chronoamperometry and cyclic voltammetry. The first linear section was in the range of 0.1–5 mM with a limit of detection of 0.115 μmol l −1 and the second linear section was raised to 120 mM with a correlation factor of 0.256 μmol l −1 (S/N of 3). Moreover, the sensor presented excellent stability, selectivity, repeatability and reproducibility. These excellent performances make AgNPs-PPy/GCE an ideal nonenzymatic H 2 O 2 sensor.

The preparation and electrochemical performances of LiFePO4-multiwalled nanotubes composite cathode materials for lithium ion batteries

International Nuclear Information System (INIS)

Feng Yan

2010-01-01

LiFePO 4 -MWCNTs (multi-walled carbon nanotubes) composite cathode materials were prepared by mixing LiFePO 4 and MWCNTs in ethanol followed by heat-treatment at 500 deg. C for 5 h. The structural, morphology and electrochemical performances of LiFePO 4 -MWCNTs composite materials were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), galvanostatic charge-discharge cycle tests, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicated that MWCNTs adding improved the electronic conductivity, the discharge capacity, cycle stability and lithium ion diffusion kinetics of LiFePO 4 , but MWCNTs adding did not charge the orthorhombic olivine-type structure of LiFePO 4 . In all these prepared LiFePO 4 with x wt.% MWCNTs (x = 4, 7, 10) composites, 7 wt.% MWCNTs adding composite cathode shows the best electrochemical performance, which gets an initial discharge capacity of 152.7 mAh g -1 at 0.18 C discharge rates with capacity retention ratio of 97.77% after 100 cycles.

Facile hydrothermal synthesis of polyhedral Fe3O4 nanocrystals, influencing factors and application in the electrochemical detection of H2O2

International Nuclear Information System (INIS)

Yuan Kefeng; Ni Yonghong; Zhang Li

2012-01-01

Highlights: ► Fe 3 O 4 polyhedra had been successfully synthesized by a facile hydrothermal technology. ► The as-obtained product exhibited the room-temperature ferrimagnetic property. ► The final product could be prepared into an electrochemical sensor for the detection of H 2 O 2 . - Abstract: Polyhedral Fe 3 O 4 nanocrystals have been successfully synthesized by a facile hydrothermal technique, employing FeSO 4 ·7H 2 O, N 2 H 4 and NH 3 ·H 2 O as the reactants without the assistance of any surfactant. The phase of the as-obtained Fe 3 O 4 was characterized by X-ray powder diffraction (XRD) and further proved by Rietveld refinement of XRD data. Energy dispersive spectrometry (EDS) and scanning electron microscopy (SEM) were used for the composition and morphology analyses of the final product. Some factors influencing the formation of polyhedral Fe 3 O 4 nanocrystals were systematically investigated, including the reaction temperature and time, and the original volume ratio of NH 3 ·H 2 O/N 2 H 4 ·H 2 O. It was found that the as-prepared Fe 3 O 4 polyhedra exhibited a good electrochemical property in 0.1 M phosphate buffer solution (PBS) with pH 7.0 and could be prepared into an electrochemical sensor for the detection of H 2 O 2 . The linear response range of the sensor was 10.0 × 10 −6 to 140.0 × 10 −6 M and a sensitivity was 11.05 μA/mM. Furthermore, the room-temperature magnetic property of the product was also investigated.

Liquid-phase exfoliated graphene as highly-sensitive sensor for simultaneous determination of endocrine disruptors: Diethylstilbestrol and estradiol

Energy Technology Data Exchange (ETDEWEB)

Hu, Lintong; Cheng, Qin [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Chen, Danchao; Ma, Ming [Ningbo Entry-exit Inspection and Quarantine Bureau of China, Ningbo 315012 (China); Wu, Kangbing, E-mail: kbwu@hust.edu.cn [Key Laboratory for Large-Format Battery Materials and System, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

2015-02-11

Graphical abstract: - Highlights: • A novel electrochemical sensor was developed for diethylstilbestrol and estradiol. • Graphene prepared by solvent exfoliation greatly enhances the detection sensitivity. • The newly-developed method has promising application and the accuracy is good. - Abstract: It is quite important to develop convenient and rapid analytical methods for trace levels of endocrine disruptors because they heavily affect health and reproduction of humans and animals. Herein, graphene was easily prepared via one-step exfoliation using N-methyl-2-pyrrolidone as solvent, and then used to construct an electrochemical sensor for highly-sensitive detection of diethylstilbestrol (DES) and estradiol (E2). On the surface of prepared graphene film, two independent and greatly-increased oxidation waves were observed at 0.28 V and 0.49 V for DES and E2. The remarkable signal enlargements indicated that the detection sensitivity was improved significantly. The influences of pH value, amount of graphene and accumulation time on the oxidation signals of DES and E2 were discussed. As a result, a highly-sensitive and rapid electrochemical method was newly developed for simultaneous detection of DES and E2. The values of detection limit were evaluated to be 10.87 nM and 4.9 nM for DES and E2. Additionally, this new method was successfully used in lake water samples and the accuracy was satisfactory.

Smart electrochemical biosensors: From advanced materials to ultrasensitive devices

Energy Technology Data Exchange (ETDEWEB)

Sadik, Omowunmi A., E-mail: osadik@binghamton.ed [Department of Chemistry, Center for Advanced Sensors and Environmental Monitoring (CASE), State University of New York-Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States); Mwilu, Samuel K.; Aluoch, Austin [Department of Chemistry, Center for Advanced Sensors and Environmental Monitoring (CASE), State University of New York-Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States)

2010-05-30

The specificity, simplicity, and inherent miniaturization afforded by advances in modern electronics have allowed electrochemical sensors to rival the most advanced optical protocols. One major obstacle in implementing electrochemistry for studying biomolecular reaction is its inadequate sensitivity. Recent reports however showed unprecedented sensitivities for biomolecular recognition using enhanced electronic amplification provided by new classes of electrode materials (e.g. carbon nanotubes, metal nanoparticles, and quantum dots). Biosensor technology is one area where recent advances in nanomaterials are pushing the technological limits of electrochemical sensitivities, thus allowing for the development of new sensor chemistries and devices. This work focuses on our recent work, based on metal-enhanced electrochemical detection, and those of others in combining advanced nanomaterials with electrochemistry for the development of smart sensors for proteins, nucleic acids, drugs and cancer cells.

Smart electrochemical biosensors: From advanced materials to ultrasensitive devices

International Nuclear Information System (INIS)

Sadik, Omowunmi A.; Mwilu, Samuel K.; Aluoch, Austin

2010-01-01

The specificity, simplicity, and inherent miniaturization afforded by advances in modern electronics have allowed electrochemical sensors to rival the most advanced optical protocols. One major obstacle in implementing electrochemistry for studying biomolecular reaction is its inadequate sensitivity. Recent reports however showed unprecedented sensitivities for biomolecular recognition using enhanced electronic amplification provided by new classes of electrode materials (e.g. carbon nanotubes, metal nanoparticles, and quantum dots). Biosensor technology is one area where recent advances in nanomaterials are pushing the technological limits of electrochemical sensitivities, thus allowing for the development of new sensor chemistries and devices. This work focuses on our recent work, based on metal-enhanced electrochemical detection, and those of others in combining advanced nanomaterials with electrochemistry for the development of smart sensors for proteins, nucleic acids, drugs and cancer cells.

Palladium nanoparticles in electrochemical sensing of trace terazosin in human serum and pharmaceutical preparations

Energy Technology Data Exchange (ETDEWEB)

Sefid-sefidehkhan, Yasaman [Department of Chemistry, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Nekoueian, Khadijeh [Laboratory of Green Chemistry, Faculty of Technology, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Amiri, Mandana, E-mail: mandanaamiri@uma.ac.ir [Department of Chemistry, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Sillanpaa, Mika [Laboratory of Green Chemistry, Faculty of Technology, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli (Finland); Eskandari, Habibollah [Department of Chemistry, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of)

2017-06-01

In this approach, palladium nanoparticle film was simply fabricated on the surface of carbon paste electrode by electrochemical deposition method. The film was characterized using scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The prepared electrode exhibited an excellent electrocatalytic activity toward detection of trace amounts of terazosin, which is an antihypertensive drug. Under the optimum experimental conditions, a linear range of 1.0 × 10{sup −8}–1.0 × 10{sup −3} mol L{sup −1} with a detection limit of 1.9 × 10{sup −9} mol L{sup −1} was obtained for determination of terazosin using differential pulse voltammetry as a sensitive method. The efficiency of palladium nanoparticle film on the surface of carbon paste electrode successfully proved for determination of terazosin in pharmaceutical sample and human serum sample with promising recovery results. The effect of some foreign species has been studied. - Highlights: • PdNPs were simply fabricated by electrochemical deposition. • PdNPs exhibited an excellent electrocatalytic activity toward oxidation of terazosin. • Terazosin has been determined in pharmaceutical sample and human serum sample.

Reliable clinical serum analysis with reusable electrochemical sensor: Toward point-of-care measurement of the antipsychotic medication clozapine.

Science.gov (United States)

Kang, Mijeong; Kim, Eunkyoung; Winkler, Thomas E; Banis, George; Liu, Yi; Kitchen, Christopher A; Kelly, Deanna L; Ghodssi, Reza; Payne, Gregory F

2017-09-15

Clozapine is one of the most promising medications for managing schizophrenia but it is under-utilized because of the challenges of maintaining serum levels in a safe therapeutic range (1-3μM). Timely measurement of serum clozapine levels has been identified as a barrier to the broader use of clozapine, which is however challenging due to the complexity of serum samples. We demonstrate a robust and reusable electrochemical sensor with graphene-chitosan composite for rapidly measuring serum levels of clozapine. Our electrochemical measurements in clinical serum from clozapine-treated and clozapine-untreated schizophrenia groups are well correlated to centralized laboratory analysis for the readily detected uric acid and for the clozapine which is present at 100-fold lower concentration. The benefits of our electrochemical measurement approach for serum clozapine monitoring are: (i) rapid measurement (≈20min) without serum pretreatment; (ii) appropriate selectivity and sensitivity (limit of detection 0.7μM); (iii) reusability of an electrode over several weeks; and (iv) rapid reliability testing to detect common error-causing problems. This simple and rapid electrochemical approach for serum clozapine measurements should provide clinicians with the timely point-of-care information required to adjust dosages and personalize the management of schizophrenia. Copyright © 2017 Elsevier B.V. All rights reserved.

Method of preparing porous, rigid ceramic separators for an electrochemical cell. [Patent application

Science.gov (United States)

Bandyopadhyay, G.; Dusek, J.T.

Porous, rigid separators for electrochemical cells are prepared by first calcining particles of ceramic material at temperatures above about 1200/sup 0/C for a sufficient period of time to reduce the sinterability of the particles. A ceramic powder that has not been calcined is blended with the original powder to control the porosity of the completed separator. The ceramic blend is then pressed into a sheet of the desired shape and sintered at a temperature somewhat lower than the calcination temperature. Separator sheets of about 1 to 2.5 mm thickness and 30 to 70% porosity can be prepared by this technique. Ceramics such as yttria, magnesium oxide, and magnesium-aluminium oxide have advantageously been used to form separators by this method.

Origin of the different behavior of some platinum decorated nanocarbons towards the electrochemical oxidation of hydrogen peroxide

International Nuclear Information System (INIS)

Malara, A.; Leonardi, S.G.; Bonavita, A.; Fazio, E.; Stelitano, S.; Neri, G.; Neri, F.; Santangelo, S.

2016-01-01

The electrochemical behavior of different platinum-decorated nanocarbons (Pt@C) towards the oxidation of hydrogen peroxide (H_2O_2) was investigated. Three different types of nanocarbons were considered: i) carbon black, ii) dahlia-like carbon nanohorns and iii) carbon nanotubes, which included both commercial (single-wall and multi-wall) and laboratory prepared (multi-wall) samples. Shape and size distribution of the platinum nanoparticles and morphology of the nanocarbons were analyzed by transmission electron microscopy. Their nanostructure was investigated by micro-Raman spectroscopy, while elemental composition of the samples and chemical bonding states were studied by X-ray photoelectron spectroscopy. Electrochemical behavior towards H_2O_2 oxidation was evaluated by means of cyclic voltammetry modifying the working screen-printed carbon electrode surface with the prepared Pt@C nanocomposites. Data obtained suggest that the size and dispersion of the Pt nanoparticles play a key role in increasing the sensitivity towards H_2O_2 detection. Thanks to the presence of smaller and more dispersed platinum particles and of a greater amount of platinum hydroxide, acting as intermediary in the H_2O_2 oxidation process, Pt@dahlia-like carbon nanohorns result to be the most promising platform for the development of H_2O_2 electrochemical sensors. - Highlights: • Different nanocarbons are decorated with Pt nanoparticles by wet impregnation method. • Pt@C-based hybrids are tested as active materials for sensing of hydrogen peroxide. • Sensor based on Pt@dahlia-like carbon nanohorns is the most performing device. • The origin of the different electrochemical behaviour is investigated. • Pt@C sensing performances are correlated with their structural and surface properties.

Cellulose-based graft copolymers prepared by simplified electrochemically mediated ATRP

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P. Chmielarz

2017-02-01

Full Text Available Brush-shaped block copolymer with a dual hydrophilic poly(acrylic acid-block-poly(oligo(ethylene glycol acrylate (PAA-b-POEGA arms was synthesized for the first time via a simplified electrochemically mediated ATRP (seATRP under both constant potential electrolysis and constant current electrolysis conditions, utilizing only 30 ppm of catalyst complex. The polymerization conditions were optimized to provide fast reactions while employing low catalyst concentrations and preparation of cellulose-based brush-like copolymers with narrow molecular weight distributions. The results from proton nuclear magnetic resonance (1H NMR spectral studies support the formation of cellulose-based graft (copolymers. It is expected that these new polymer brushes may find application as pH- and thermo-sensitive drug delivery systems.

Fabrication of electrochemical theophylline sensor based on manganese oxide nanoparticles/ionic liquid/chitosan nanocomposite modified glassy carbon electrode

International Nuclear Information System (INIS)

MansouriMajd, Samira; Teymourian, Hazhir; Salimi, Abdollah; Hallaj, Rahman

2013-01-01

In this study, the preparation of a glassy carbon (GC) electrode modified with chitosan/NH 2 -ionic liquid/manganese oxide nanoparticles (Chit/NH 2 -IL/MnO x ) was described for electrocatalytic detection of theophylline (TP). First, chitosan hydrogel (Chit) was electrodeposited on the GC electrode surface at a constant potential (−1.5 V) in acidic solution. Then, the previously synthesized amine-terminated 1-(3-Aminopropyl)-3-methylimidazolium bromide ionic liquid (NH 2 -IL) was covalently attached to the modified electrode via glutaraldehyde (GA) as linking agent. Finally, manganese oxide (MnO x ) nanoparticles were electrodeposited onto the Chit/NH 2 -IL film by potential cycling between −1.0 and 1.7 V in Mn(CH 3 COO) 2 ·4H 2 O neutral aqueous solution. Electrochemical behavior of the modified electrode was evaluated by cyclic voltammetry (CV) technique. The charge transfer coefficient (α) and electron transfer rate constant (k s ) for MnOOH/MnO 2 redox couple were calculated to be 0.35 and 1.62 s −1 , respectively. The resulting system brings new capabilities for electrochemical sensing through combining the advantages of IL and MnO x nanoparticles. The differential pulse voltammetric (DPV) results indicated the high ability of GC/Chit/NH 2 -IL/MnO x modified electrode to catalyze the oxidation of TP. DPV determination of TP in acetate buffer solution (pH 5) gave linear responses over the concentration range up to 120 μM with the detection limit of 50 nM and sensitivity of 804 nA μM −1 . Furthermore, the applicability of the sensor for TP analysis in pharmaceutical samples has been successfully demonstrated

Electrochemical preparation of iron cuboid nanoparticles and their catalytic properties for nitrite reduction

International Nuclear Information System (INIS)

Chen Yanxin; Chen Shengpei; Chen Qingsong; Zhou Zhiyou; Sun Shigang

2008-01-01

Iron cuboid nanoparticles supported on glassy carbon (denoted nm-Fe/GC) were prepared by electrochemical deposition under cyclic voltammetric (CV) conditions. The structure and composition of the Fe nanomaterials were characterized by scanning electron microscopy (SEM), selected area electron diffraction (SAED), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). The results demonstrated that the Fe cuboid nanoparticles are dispersed discretely on GC substrate with an average size ca. 171 nm, and confirmed that the electrochemical synthesized nanocubes are single crystals of pure Fe. The catalytic properties of the Fe cuboid nanoparticles towards nitrite electroreduction were investigated, and enhanced electrocatalytic activity of the Fe nanocubes has been determined. In comparison with the data obtained on a bulk-Fe electrode, the onset potential of nitrite reduction on nm-Fe/GC is positively sifted by 100 mV, and the steady reduction current density is enhanced about 2.4-3.2 times

Impact Analysis of Temperature and Humidity Conditions on Electrochemical Sensor Response in Ambient Air Quality Monitoring.

Science.gov (United States)

Wei, Peng; Ning, Zhi; Ye, Sheng; Sun, Li; Yang, Fenhuan; Wong, Ka Chun; Westerdahl, Dane; Louie, Peter K K

2018-01-23

The increasing applications of low-cost air sensors promises more convenient and cost-effective systems for air monitoring in many places and under many conditions. However, the data quality from such systems has not been fully characterized and may not meet user expectations in research and regulatory uses, or for use in citizen science. In our study, electrochemical sensors (Alphasense B4 series) for carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO₂), and oxidants (O x ) were evaluated under controlled laboratory conditions to identify the influencing factors and quantify their relation with sensor outputs. Based on the laboratory tests, we developed different correction methods to compensate for the impact of ambient conditions. Further, the sensors were assembled into a monitoring system and tested in ambient conditions in Hong Kong side-by-side with regulatory reference monitors, and data from these tests were used to evaluate the performance of the models, to refine them, and validate their applicability in variable ambient conditions in the field. The more comprehensive correction models demonstrated enhanced performance when compared with uncorrected data. One over-arching observation of this study is that the low-cost sensors may promise excellent sensitivity and performance, but it is essential for users to understand and account for several key factors that may strongly affect the nature of sensor data. In this paper, we also evaluated factors of multi-month stability, temperature, and humidity, and considered the interaction of oxidant gases NO₂ and ozone on a newly introduced oxidant sensor.

Impact Analysis of Temperature and Humidity Conditions on Electrochemical Sensor Response in Ambient Air Quality Monitoring

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Peng Wei

2018-01-01

Full Text Available The increasing applications of low-cost air sensors promises more convenient and cost-effective systems for air monitoring in many places and under many conditions. However, the data quality from such systems has not been fully characterized and may not meet user expectations in research and regulatory uses, or for use in citizen science. In our study, electrochemical sensors (Alphasense B4 series for carbon monoxide (CO, nitric oxide (NO, nitrogen dioxide (NO2, and oxidants (Ox were evaluated under controlled laboratory conditions to identify the influencing factors and quantify their relation with sensor outputs. Based on the laboratory tests, we developed different correction methods to compensate for the impact of ambient conditions. Further, the sensors were assembled into a monitoring system and tested in ambient conditions in Hong Kong side-by-side with regulatory reference monitors, and data from these tests were used to evaluate the performance of the models, to refine them, and validate their applicability in variable ambient conditions in the field. The more comprehensive correction models demonstrated enhanced performance when compared with uncorrected data. One over-arching observation of this study is that the low-cost sensors may promise excellent sensitivity and performance, but it is essential for users to understand and account for several key factors that may strongly affect the nature of sensor data. In this paper, we also evaluated factors of multi-month stability, temperature, and humidity, and considered the interaction of oxidant gases NO2 and ozone on a newly introduced oxidant sensor.

Impact Analysis of Temperature and Humidity Conditions on Electrochemical Sensor Response in Ambient Air Quality Monitoring

Science.gov (United States)

Ning, Zhi; Ye, Sheng; Sun, Li; Yang, Fenhuan; Wong, Ka Chun; Westerdahl, Dane; Louie, Peter K. K.

2018-01-01

The increasing applications of low-cost air sensors promises more convenient and cost-effective systems for air monitoring in many places and under many conditions. However, the data quality from such systems has not been fully characterized and may not meet user expectations in research and regulatory uses, or for use in citizen science. In our study, electrochemical sensors (Alphasense B4 series) for carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO2), and oxidants (Ox) were evaluated under controlled laboratory conditions to identify the influencing factors and quantify their relation with sensor outputs. Based on the laboratory tests, we developed different correction methods to compensate for the impact of ambient conditions. Further, the sensors were assembled into a monitoring system and tested in ambient conditions in Hong Kong side-by-side with regulatory reference monitors, and data from these tests were used to evaluate the performance of the models, to refine them, and validate their applicability in variable ambient conditions in the field. The more comprehensive correction models demonstrated enhanced performance when compared with uncorrected data. One over-arching observation of this study is that the low-cost sensors may promise excellent sensitivity and performance, but it is essential for users to understand and account for several key factors that may strongly affect the nature of sensor data. In this paper, we also evaluated factors of multi-month stability, temperature, and humidity, and considered the interaction of oxidant gases NO2 and ozone on a newly introduced oxidant sensor. PMID:29360749

A novel voltammetric sensor for ascorbic acid based on molecularly imprinted poly(o-phenylenediamine-co-o-aminophenol).

Science.gov (United States)

Kong, Yong; Shan, Xueling; Ma, Jianfeng; Chen, Meilan; Chen, Zhidong

2014-01-27

A molecularly imprinted copolymer, poly(o-phenylenediamine-co-o-aminophenol) (PoPDoAP), was prepared as a new ascorbic acid (AA) sensor. The copolymer was synthesized by incorporation of AA as template molecules during the electrochemical copolymerization of o-phenylenediamine and o-aminophenol, and complementary sites were formed after the copolymer was electrochemically reduced in ammonium aqueous solution. The molecularly imprinted copolymer sensor exhibited a high sensitivity and selectivity toward AA. Differential pulse voltammograms (DPVs) showed a linear concentration range of AA from 0.1 to 10 mM, and the detection limit was calculated to be 36.4 μM. Compared to conventional polyaniline-based AA sensors, the analytical performance of the imprinted copolymer sensor was improved due to the broadened usable pH range of PoPDoAP (from pH 1.0 to pH 8.0). The sensor also exhibited a good reproducibility and stability. And it has been successfully applied in the determination of AA in real samples, including vitamin C tablet and orange juices, with satisfactory results. Copyright © 2013 Elsevier B.V. All rights reserved.

Electrochemical Detection with Preconcentration: Nitroenergetic Contaminants

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Brandy J. Johnson

2014-06-01

Full Text Available This effort evaluated the potential of two prototype devices for enhanced electrochemical detection of 2,4,6-trinitrotoluene (TNT and dinitrotoluene (DNT following preconcentration using an organosilicate sorbent. The bench-scale prototype provides adsorption of the targets from aqueous solution followed by elution in a mixture of methanol and potassium chloride (KCl. Following elution, the eluant is diluted using an aqueous KCl solution to provide sufficient electrolyte for electrochemical analysis. Concentrations of methanol greater than 50% were detrimental to sensor performance and lifetime. Calibration of the electrochemical sensor was completed and results of electrochemical analysis were compared to those of HPLC analysis over a range of concentrations and in varied matrices. TNT detection was found to be consistent and detection limits were improved from 200 ppb to 3 ppb depending on the sample volume utilized. DNT detection showed higher variability and significantly greater false response rates. On the basis of these results, a second, more advanced, prototype was developed and utilized in limited field trials with the intention of moving the technology toward in situ applications.

The preparation and properties of a novel electrolyte of electrochemical double layer capacitors based on LiPF6 and acetamide

International Nuclear Information System (INIS)

Li Qi; Zuo Xiaoxi; Liu Jiansheng; Xiao Xin; Shu Dong; Nan Junmin

2011-01-01

A novel electrolyte applied in electrochemical double-layer capacitors (EDLCs) has been prepared based on lithium hexafluorophosphate (LiPF 6 ) and acetamide and subsequently characterized by differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), electrochemical techniques and so on. The mixtures of LiPF 6 and acetamide at the molar ratios of 1:4 to 1:6 exist as liquids below 25 °C, which is attributed to the melting point depression of mixture and the coordination of the polar groups (C=O and NH groups) of acetamide with Li + and PF 6 − ions. The strong interaction between LiPF 6 and acetamide results in the rupture of the electrovalent bond of LiPF 6 and the breakage of hydrogen bonds among the acetamide molecules, leading to the formation of a liquid electrolyte. The LiPF 6 /acetamide electrolyte with a molar ratio of 1:5.5 exhibits a 5.2 V electrochemical window and suitable ionic conductivity at room temperature. In particular, the coin-type cells with carbon electrodes and LiPF 6 /acetamide electrolyte possess high thermal stability and electrochemical properties, showing that the as-prepared LiPF 6 /acetamide electrolyte is a promising candidate for EDLCs.

Poly(3,6-diamino-9-ethylcarbazole) based molecularly imprinted polymer sensor for ultra-sensitive and selective detection of 17-β-estradiol in biological fluids.

Science.gov (United States)

Liu, Weilu; Li, Haifeng; Yu, Shangmin; Zhang, Jiaxing; Zheng, Weihua; Niu, Liting; Li, Gengen

2018-05-01

In this work, we reported the synthesis of 3, 6-diamino-9-ethylcarbazole and its application as a new monomer for preparation of molecularly imprinted polymer (MIP) electrochemical sensor. The as prepared MIP sensor exhibited ultrahigh sensitivity and selectivity for the detection of 17-β-estradiol in attomolar levels (1 × 10 -18 molL -1 ). The sensor works by detecting the change of the interfacial impedance that is derived from recognition of 17-β-estradiol on the MIP layer. The MIP sensor based on 3, 6-diamino-9-ethylcarbazole monomer revealed better performance than that of unmodified carbazole monomer. The monomer/template ratio, electropolymerization scanning cycles, and the incubation pH values were optimised in order to obtain the best detection efficiency. Under the optimised condition, the MIP sensor exhibits a wide linear range from 1aM to 10μM (1 × 10 -18 ̶ 1 × 10 -5 molL -1 ). A low detection limit of 0.36aM (3.6 × 10 -19 molL -1 ) and a good selectivity towards structurally similar compounds were obtained. The proposed MIP sensor also exhibits long-term stability and applicability in human serum samples. These advantages enabled this MIP sensor to be a promising alternative of electrochemical sensor and may be extended to detection of other endogenous compounds. Copyright © 2018 Elsevier B.V. All rights reserved.

A new way for preparing superconducting materials: the electrochemical oxidation of La2CuO4

International Nuclear Information System (INIS)

Wattiaux, A.; Park, J.C.; Grenier, J.C.; Pouchard, M.

1990-01-01

The electrochemical oxidation in alkaline medium is described as a new way for preparing superconducting oxides at room temperature. The application of this method to La 2 CuO 4 gave rise to a metallic material with a superconducting behaviour below 39 K and whose physical and chemical features appear as quite promising [fr

Citrus maxima (Pomelo) juice mediated eco-friendly synthesis of ZnO nanoparticles: Applications to photocatalytic, electrochemical sensor and antibacterial activities

Science.gov (United States)

Pavithra, N. S.; Lingaraju, K.; Raghu, G. K.; Nagaraju, G.

2017-10-01

In the present work, Zinc oxide nanoparticles (ZnO Nps) have been successfully prepared through a simple, effective and low cost solution combustion method using Zn (NO3)2·6H2O as an oxidizer, chakkota (Common name = Pomelo) fruit juice as novel fuel. X-ray diffraction pattern indicates the hexagonal wurtzite structure with average crystallite size of 22 nm. ZnO Nps were characterized with the aid of different spectroscopic techniques such as Raman spectroscopy, Fourier Transform Infrared spectroscopy, Photoluminescence and UV-Visible spectroscopy. FTIR shows characteristic ZnO vibrational mode at 393 cm- 1. SEM images show that the particles are agglomerated. TEM image shows the size of the particles are about 10-20 nm. Further, in order to establish practical applicability of the synthesized ZnO Nps, photocatalytic degradation of methylene blue (MB) dye as a model system was studied in presence of UV (665 nm) light. In addition to this, the antibacterial activity was screen against 3 bacterial strains and electrochemical sensor performance towards the quantification of dopamine at nano molar concentrations was also explored.

Construction of an Electrochemical Sensor Based on Carbon Nanotubes/Gold Nanoparticles for Trace Determination of Amoxicillin in Bovine Milk

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Aliyu Muhammad

2016-01-01

Full Text Available In this work, a novel electrochemical sensor was fabricated for determination of amoxicillin in bovine milk samples by decoration of carboxylated multi-walled carbon nanotubes (MWCNTs with gold nanoparticles (AuNPs using ethylenediamine (en as a cross linker (AuNPs/en-MWCNTs. The constructed nanocomposite was homogenized in dimethylformamide and drop casted on screen printed electrode. Field emission scanning electron microscopy (FESEM, energy dispersive X-Ray (EDX, X-Ray diffraction (XRD and cyclic voltammetry were used to characterize the synthesized nanocomposites. The results show that the synthesized nanocomposites induced a remarkable synergetic effect for the oxidation of amoxicillin. Effect of some parameters, including pH, buffer, scan rate, accumulation potential, accumulation time and amount of casted nanocomposites, on the sensitivity of fabricated sensor were optimized. Under the optimum conditions, there was two linear calibration ranges from 0.2–10 µM and 10–30 µM with equations of Ipa (µA = 2.88C (µM + 1.2017; r = 0.9939 and Ipa (µA = 0.88C (µM + 22.97; r = 0.9973, respectively. The limit of detection (LOD and limit of quantitation (LOQ were calculated as 0.015 µM and 0.149 µM, respectively. The fabricated electrochemical sensor was successfully applied for determination of Amoxicillin in bovine milk samples and all results compared with high performance liquid chromatography (HPLC standard method.

Electrochemical sensor based on molecularly imprinted polymer film via sol-gel technology and multi-walled carbon nanotubes-chitosan functional layer for sensitive determination of quinoxaline-2-carboxylic acid.

Science.gov (United States)

Yang, Yukun; Fang, Guozhen; Liu, Guiyang; Pan, Mingfei; Wang, Xiaomin; Kong, Lingjie; He, Xinlei; Wang, Shuo

2013-09-15

Quinoxaline-2-carboxylic acid (QCA) is difficult to measure since only trace levels are present in commercial meat products. In this study, a rapid, sensitive and selective molecularly imprinted electrochemical sensor for QCA determination was successfully constructed by combination of a novel modified glassy carbon electrode (GCE) and differential pulse voltammetry (DPV). The GCE was fabricated via stepwise modification of multi-walled carbon nanotubes (MWNTs)-chitosan (CS) functional composite and a sol-gel molecularly imprinted polymer (MIP) film on the surface. MWNTs-CS composite was used to enhance the electron transfer rate and expand electrode surface area, and consequently amplify QCA reduction electrochemical response. The imprinted mechanism and experimental parameters affecting the performance of MIP film were discussed in detail. The resulting MIP/sol-gel/MWNTs-CS/GCE was characterized using various electrochemical methods involving cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and DPV. The sensor using MIP/sol-gel/MWNTs-CS/GCE as working electrode showed a linear current response to the target QCA concentration in the wide range from 2.0×10(-6) to 1.0×10(-3)molL(-1) with a low detection limit of 4.4×10(-7)molL(-1) (S/N=3). The established sensor with excellent reproductivity and stability was applied to evaluate commercial pork products. At five concentration levels, the recoveries and standard deviations were calculated as 93.5-98.6% and 1.7-3.3%, respectively, suggesting the proposed sensor is promising for the accurate quantification of QCA at trace levels in meat samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Continuous fatigue crack monitoring of bridges: Long-Term Electrochemical Fatigue Sensor (LTEFS)

Science.gov (United States)

Moshier, Monty A.; Nelson, Levi; Brinkerhoff, Ryan; Miceli, Marybeth

2016-04-01

Fatigue cracks in steel bridges degrade the load-carrying capacity of these structures. Fatigue damage accumulation caused by the repetitive loading of everyday truck traffic can cause small fatigue cracks initiate. Understanding the growth of these fatigue cracks is critical to the safety and reliability of our transportation infrastructure. However, modeling fatigue in bridges is difficult due to the nature of the loading and variations in connection integrity. When fatigue cracks reach critical lengths failures occur causing partial or full closures, emergency repairs, and even full structural failure. Given the aging US highway and the trend towards asset management and life extension, the need for reliable, cost effective sensors and monitoring technologies to alert bridge owners when fatigue cracks are growing is higher than ever. In this study, an innovative Long-Term Electrochemical Fatigue Sensor (LTEFS) has been developed and introduced to meet the growing NDT marketplace demand for sensors that have the ability to continuously monitor fatigue cracks. The performance of the LTEFS has been studied in the laboratory and in the field. Data was collected using machined specimens with different lengths of naturally initiated fatigue cracks, applied stress levels, applied stress ratios, and for both sinusoidal and real-life bridge spectrum type loading. The laboratory data was evaluated and used to develop an empirically based algorithm used for crack detection. Additionally, beta-tests on a real bridge structure has been completed. These studies have conclusively demonstrated that LTEFS holds great potential for long-term monitoring of fatigue cracks in steel structures

Design and Operation of an Electrochemical Methanol Concentration Sensor for Direct Methanol Fuel Cell Systems

Science.gov (United States)

Narayanan, S. R.; Valdez, T. I.; Chun, W.

2000-01-01

The development of a 150-Watt packaged power source based on liquid feed direct methanol fuel cells is being pursued currently at the Jet propulsion Laboratory for defense applications. In our studies we find that the concentration of methanol in the fuel circulation loop affects the electrical performance and efficiency the direct methanol fuel cell systems significantly. The practical operation of direct methanol fuel cell systems, therefore, requires accurate monitoring and control of methanol concentration. The present paper reports on the principle and demonstration of an in-house developed electrochemical sensor suitable for direct methanol fuel cell systems.

Graphene–palladium nanowires based electrochemical sensor using ZnFe2O4–graphene quantum dots as an effective peroxidase mimic

International Nuclear Information System (INIS)

Liu, Weiyan; Yang, Hongmei; Ma, Chao; Ding, Ya-nan; Ge, Shenguang; Yu, Jinghua; Yan, Mei

2014-01-01

Highlights: • The nanohybrid ZnFe 2 O 4 /GQDs was developed by assembling the GQDs on the ZnFe 2 O 4 through a photo-Fenton reaction. • The ZnFe 2 O 4 /GQDs exhibited higher peroxidase-like activity and better stability than each individual and HRP. • An electrochemical sensor was fabricated using ZnFe 2 O 4 /GQDs nanohybrid as a mimic enzymatic to detect DNA. • Graphene and Pd nanowires were modified on the glassy carbon electrode, which improved the electronic transfer rate. - Abstract: We proposed an electrochemical DNA sensor by using peroxidase-like magnetic ZnFe 2 O 4 –graphene quantum dots (ZnFe 2 O 4 /GQDs) nanohybrid as a mimic enzymatic label. Aminated graphene and Pd nanowires were successively modified on glassy carbon electrode, which improved the electronic transfer rate as well as increased the amount of immobilized capture ssDNA (S1). The nanohybrid ZnFe 2 O 4 /GQDs was prepared by assembling the GQDs on the surface of ZnFe 2 O 4 through a photo-Fenton reaction, which was not only used as a mimic enzyme but also as a carrier to label complementary ssDNA (S3). By synergistically integrating highly catalytically activity of nano-sized GQDs and ZnFe 2 O 4 , the nanohybrid possessed highly-efficient peroxidase-like catalytic activity which could produce a large current toward the reduction of H 2 O 2 for signal amplification. Thionine was used as an excellent electron mediator. Compared with traditional enzyme labels, the mimic enzyme ZnFe 2 O 4 /GQDs exhibited many advantages such as environment friendly and better stability. Under the optimal conditions, the approach provided a wide linear range from 10 −16 to 5 × 10 −9 M and low detection limit of 6.2 × 10 −17 M. The remarkable high catalytic capability could allow the nanohybrid to replace conventional peroxidase-based assay systems. The new, robust and convenient assay systems can be widely utilized for the identification of other target molecules

Metal/Metal Oxide Differential Electrode pH Sensors

Science.gov (United States)

West, William; Buehler, Martin; Keymeulen, Didier

2007-01-01

Solid-state electrochemical sensors for measuring the degrees of acidity or alkalinity (in terms of pH values) of liquid solutions are being developed. These sensors are intended to supplant older electrochemical pH sensors that include glass electrode structures and reference solutions. The older sensors are fragile and subject to drift. The present developmental solid-state sensors are more rugged and are expected to be usable in harsh environments. The present sensors are based on a differential-electrode measurement principle. Each sensor includes two electrodes, made of different materials, in equilibrium with the solution of interest.

Prussian blue mediated amplification combined with signal enhancement of ordered mesoporous carbon for ultrasensitive and specific quantification of metolcarb by a three-dimensional molecularly imprinted electrochemical sensor.

Science.gov (United States)

Yang, Yukun; Cao, Yaoyu; Wang, Xiaomin; Fang, Guozhen; Wang, Shuo

2015-02-15

In this work, we presented a three-dimensional (3D) molecularly imprinted electrochemical sensor (MIECS) with novel strategy for ultrasensitive and specific quantification of metolcarb based on prussian blue (PB) mediated amplification combined with signal enhancement of ordered mesoporous carbon. The molecularly imprinted polymers were synthesized by electrochemically induced redox polymerization of para aminobenzoic acid (p-ABA) in the presence of template metolcarb. Ordered mesoporous carbon material (CMK-3) was introduced to enhance the electrochemical response by improving the structure of the modified electrodes and facilitating charge transfer processes of PB which was used as an inherent electrochemical active probe. The modification process for the working electrodes of the MIECS was characterized by scanning electron microscope (SEM) and cyclic voltammetry (CV), and several important parameters controlling the performance of the MIECS were investigated and optimized in detail. The MIECS with 3D structure had the advantages of ease of preparation, high porous surface structure, speedy response, ultrasensitivity, selectivity, reliable stability, good reproducibility and repeatability. Under the optimal conditions, the MIECS offered an excellent current response for metolcarb in the linear response range of 5.0 × 10(-10)-1.0 × 10(-4) mol L(-1) and the limit of detection (LOD) was calculated to be 9.3 × 10 (-11)mol L(-1) (S/N = 3). The proposed MIECS has been successfully applied for the determination of metolcarb in real samples with satisfactory recoveries. Furthermore, the construction route of this ultrasensitive 3D MIECS may provide a guideline for the determination of non-electroactive analytes in environmental control and food safety. Copyright © 2014 Elsevier B.V. All rights reserved.

Electrochemical performance of trimethylolpropane trimethylacrylate-based gel polymer electrolyte prepared by in situ thermal polymerization

International Nuclear Information System (INIS)

Zhou, Dong; Fan, Li-Zhen; Fan, Huanhuan; Shi, Qiao

2013-01-01

Cross-linked trimethylolpropane trimethylacrylate-based gel polymer electrolytes (GPE) were prepared by in situ thermal polymerization. The ionic conductivity of the GPEs are >10 −3 S cm −1 at 25 °C, and continuously increased with the increase of liquid electrolyte content. The GPEs have excellent electrochemical stability up to 5.0 V versus Li/Li + . The LiCoO 2 |TMPTMA-based GPE|graphite cells exhibit an initial discharge capacity of 129 mAh g −1 at the 0.2C, and good cycling stability with around 83% capacity retention after 100 cycles. Both the simple fabricating process of polymer cell and outstanding electrochemical performance of such new GPE make it potentially one of the most promising electrolyte materials for next generation lithium ion batteries

Design, Fabrication and Experimental Validation of a Novel Dry-Contact Sensor for Measuring Electroencephalography Signals without Skin Preparation

Directory of Open Access Journals (Sweden)

Chin-Teng Lin

2011-05-01

Full Text Available In the present study, novel dry-contact sensors for measuring electro-encephalography (EEG signals without any skin preparation are designed, fabricated by an injection molding manufacturing process and experimentally validated. Conventional wet electrodes are commonly used to measure EEG signals; they provide excellent EEG signals subject to proper skin preparation and conductive gel application. However, a series of skin preparation procedures for applying the wet electrodes is always required and usually creates trouble for users. To overcome these drawbacks, novel dry-contact EEG sensors were proposed for potential operation in the presence or absence of hair and without any skin preparation or conductive gel usage. The dry EEG sensors were designed to contact the scalp surface with 17 spring contact probes. Each probe was designed to include a probe head, plunger, spring, and barrel. The 17 probes were inserted into a flexible substrate using a one-time forming process via an established injection molding procedure. With these 17 spring contact probes, the flexible substrate allows for high geometric conformity between the sensor and the irregular scalp surface to maintain low skin-sensor interface impedance. Additionally, the flexible substrate also initiates a sensor buffer effect, eliminating pain when force is applied. The proposed dry EEG sensor was reliable in measuring EEG signals without any skin preparation or conductive gel usage, as compared with the conventional wet electrodes.

A novel screen-printed mast cell-based electrochemical sensor for detecting spoilage bacterial quorum signaling molecules (N-acyl-homoserine-lactones) in freshwater fish.

Science.gov (United States)

Jiang, Donglei; Liu, Yan; Jiang, Hui; Rao, Shengqi; Fang, Wu; Wu, Mangang; Yuan, Limin; Fang, Weiming

2018-04-15

A novel screen-printed cell-based electrochemical sensor was developed to assess bacterial quorum signaling molecules, N-acylhomoserine lactones (AHLs). Screen-printed carbon electrode (SPCE), which possesses excellent properties such as low-cost, disposable and energy-efficient, was modified with multi-walled carbon nanotubes (MWNTs) to improve electrochemical signals and enhance the sensitivity. Rat basophilic leukemia (RBL-2H3) mast cells encapsulated in alginate/graphene oxide (NaAgl/GO) hydrogel were immobilized on the MWNTs/SPCE to serve as recognition element. Electrochemical impedance spectroscopy (EIS) was employed to record the cell impedance signal as-influenced by Pseudomonas aeruginosa quorum-sensing molecule, N-3-oxododecanoyl homoserine lactone (3OC 12 -HSL). Experimental results show that 3OC 12 -HSL caused a significant decrease in cell viability in a dose dependent manner. The EIS value decreased with concentrations of 3OC 12 -HSL in the range of 0.1-1μM, and the detection limit for 3OC 12 -HSL was calculated to be 0.094μM. These results were confirmed via cell viability, SEM, TEM analysis. Next, the sensor was successfully applied to monitoring the production of AHLs by spoilage bacteria in three different freshwater fish juice samples which efficiently proved the practicability of this cell based method. Therefore, the proposed cell sensor may serve as an innovative and effective approach to the measurement of quorum signaling molecule and thus provides a new avenue for real-time monitoring the spoilage bacteria in freshwater fish production. Copyright © 2017 Elsevier B.V. All rights reserved.

An electrochemical dopamine sensor based on the ZnO/CuO nanohybrid structures.

Science.gov (United States)

Khun, K; Ibupoto, Z H; Liu, X; Mansor, N A; Turner, A P F; Beni, V; Willander, M

2014-09-01

The selective detection of dopamine (DA) is of great importance in the modern medicine because dopamine is one of the main regulators in human behaviour. In this study, ZnO/CuO nanohybrid structures, grown on the gold coated glass substrate, have been investigated as a novel electrode material for the electrochemical detection of dopamine. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques were used for the material characterization and the obtained results are in good agreement. The selective determination of dopamine was demonstrated by cyclic voltammetry (CV) and amperometric experiments. The amperometric response was linear for dopamine concentrations between 1.0 x 10(-3) and 8.0 mM with a sensitivity of 90.9 μA mM(-1) cm(-2). The proposed dopamine biosensor is very stable, selective over common interferents as glucose, uric acid and ascorbic acid, and also good reproducibility was observed for seven electrodes. Moreover, the dopamine sensor exhibited a fast response time of less than 10 s. The wide range and acceptable sensitivity of the presented dopamine sensor provide the possible application in analysing the dopamine from the real samples.

Non-enzymatic hydrogen peroxide detection at NiO nanoporous thin film- electrodes prepared by physical vapor deposition at oblique angles

International Nuclear Information System (INIS)

Salazar, Pedro; Rico, Victor; González-Elipe, Agustín R.

2017-01-01

Highlights: • A non-enzymatic sensor for H 2 O 2 detection based on nickel thin film is reported. • Nanostructured nickel thin films are prepared by physical vapor deposition at oblique angles. • Main analytical parameters were obtained under optimal operation conditions. • Sensors depict an outstanding selectivity and a high stability. • Sensors are successfully used to determine H 2 O 2 in antiseptic solutions. - Abstract: In this work we report a non-enzymatic sensor for hydrogen peroxide (H 2 O 2 ) detection based on nanostructured nickel thin films prepared by physical vapor deposition at oblique angles. Porous thin films deposited on ITO substrates were characterized by X-ray diffraction analysis, scanning electron microcopy (SEMs), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques such as Cyclic Voltammetry (CV) and Constant Potential Amperometry (CPA). The microstructure of the thin films consisted of inclined and separated Ni nanocolumns forming a porous thin layer of about 500 nm thickness. Prior to their use, the films surface was electrochemically modified and the chemical state studied by CV and XPS analysis. These techniques also showed that Ni 2+ /Ni 3+ species were involved in the electrochemical oxidation and detection of H 2 O 2 in alkaline medium. Main analytical parameters such as sensitivity (807 mA M −1 cm −2 ), limit of detection (3.22 μM) and linear range (0.011–2.4 mM) were obtained under optimal operation conditions. Sensors depicted an outstanding selectivity and a high stability and they were successfully used to determine H 2 O 2 concentration in commercial antiseptic solutions.

Sensitive electrochemical sensors for simultaneous determination of ascorbic acid, dopamine, and uric acid based on Au@Pd-reduced graphene oxide nanocomposites

Science.gov (United States)

Jiang, Jingjing; Du, Xuezhong

2014-09-01

Sensitive electrochemical sensors were fabricated with reduced graphene oxide-supported Au@Pd (Au@Pd-RGO) nanocomposites by one-step synthesis for individual and simultaneous determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA) with low detection limits and wide concentration ranges. From the Au@Pd-RGO-modified electrodes, well-separated oxidation peaks and enhanced peak currents of AA, DA, and UA were observed owing to the superior conductivity of RGO and the excellent catalytic activity of Au@Pd nanoparticles. For individual detection, the linear responses of AA, DA, and UA were in the concentration ranges of 0.1-1000, 0.01-100, and 0.02-500 μM with detection limits of 0.02, 0.002, and 0.005 μM (S/N = 3), respectively. For simultaneous detection by synchronous change of the concentrations of AA, DA, and UA, the linear response ranges were 1-800, 0.1-100, and 0.1-350 μM with detection limits of 0.28, 0.024, and 0.02 μM (S/N = 3), respectively. The fabricated sensors were further applied to the detection of AA, DA, and UA in urine samples. The Au@Pd-RGO nanocomposites have promising applications in highly sensitive and selective electrochemical sensing.Sensitive electrochemical sensors were fabricated with reduced graphene oxide-supported Au@Pd (Au@Pd-RGO) nanocomposites by one-step synthesis for individual and simultaneous determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA) with low detection limits and wide concentration ranges. From the Au@Pd-RGO-modified electrodes, well-separated oxidation peaks and enhanced peak currents of AA, DA, and UA were observed owing to the superior conductivity of RGO and the excellent catalytic activity of Au@Pd nanoparticles. For individual detection, the linear responses of AA, DA, and UA were in the concentration ranges of 0.1-1000, 0.01-100, and 0.02-500 μM with detection limits of 0.02, 0.002, and 0.005 μM (S/N = 3), respectively. For simultaneous detection by synchronous change of the

A Review on Direct Electrochemistry of Catalase for Electrochemical Sensors

Directory of Open Access Journals (Sweden)

Periasamy Arun Prakash

2009-03-01

Full Text Available Catalase (CAT is a heme enzyme with a Fe(III/II prosthetic group at its redox centre. CAT is present in almost all aerobic living organisms, where it catalyzes the disproportionation of H2O2 into oxygen and water without forming free radicals. In order to study this catalytic mechanism in detail, the direct electrochemistry of CAT has been investigated at various modified electrode surfaces with and without nanomaterials. The results show that CAT immobilized on nanomaterial modified electrodes shows excellent catalytic activity, high sensitivity and the lowest detection limit for H2O2 determination. In the presence of nanomaterials, the direct electron transfer between the heme group of the enzyme and the electrode surface improved significantly. Moreover, the immobilized CAT is highly biocompatible and remains extremely stable within the nanomaterial matrices. This review discusses about the versatile approaches carried out in CAT immobilization for direct electrochemistry and electrochemical sensor development aimed as efficient H2O2 determination. The benefits of immobilizing CAT in nanomaterial matrices have also been highlighted.

Nanomaterial-based Electrochemical Sensors for the Detection of Glucose and Cholesterol

Science.gov (United States)

Ahmadalinezhad, Asieh

designed glucose biosensor exhibits a wide linear range, up to 18 mM glucose, as well as high sensitivity and selectivity. Glucose measurements of human serum using the developed biosensor showed excellent agreement with the data recorded by a commercial blood glucose monitoring assay. Finally, we fabricated an enzyme-free glucose sensor based on nanoporous palladium-cadmium (PdCd) networks. A hydrothermal method was applied in the synthesis of PdCd nanomaterials. The effect of the composition of the PdCd nanomaterials on the performance of the electrode was investigated by cyclic voltammetry (CV). Amperometric studies showed that the nanoporous PdCd electrode was responsive to the direct oxidation of glucose with high electrocatalytic activity. The sensitivity of the sensor for continuous glucose monitoring was 146.21 microAmM--1cm--2, with linearity up to 10 mM and a detection limit of 0.05 mM. In summary, the electrochemical biosensors proposed in my PhD study exhibited high sensitivity and selectivity for the continuous monitoring of analytes in the presence of common interference species. Our results have shown that the performance of the biosensors is significantly dependent on the dimensions and morphologies of nanostructured materials. The unique nanomaterials-based platforms proposed in this dissertation open the door to the design and fabrication of high-performance electrochemical biosensors for medical diagnostics.

Hydrogen peroxide sensor: Uniformly decorated silver nanoparticles on polypyrrole for wide detection range

Energy Technology Data Exchange (ETDEWEB)

Nia, Pooria Moozarm, E-mail: pooriamn@yahoo.com; Meng, Woi Pei, E-mail: pmwoi@um.edu.my; Alias, Y., E-mail: yatimah70@um.edu.my

2015-12-01

Graphical abstract: - Highlights: • Electrochemical method was used for depositing silver nanoparticles and polypyrrole. • Silver nanoparticles (25 nm) were uniformly decorated on electrodeposited polypyrrole. • (Ag(NH{sub 3}){sub 2}OH) precursor showed better electrochemical performance than (AgNO{sub 3}). • The sensor showed superior performance toward H{sub 2}O{sub 2}. - Abstract: Electrochemically synthesized polypyrrole (PPy) decorated with silver nanoparticles (AgNPs) was prepared and used as a nonenzymatic sensor for hydrogen peroxide (H{sub 2}O{sub 2}) detection. Polypyrrole was fabricated through electrodeposition, while silver nanoparticles were deposited on polypyrrole by the same technique. The field emission scanning electron microscopy (FESEM) images showed that the electrodeposited AgNPs were aligned along the PPy uniformly and the mean particle size of AgNPs is around 25 nm. The electrocatalytic activity of AgNPs-PPy-GCE toward H{sub 2}O{sub 2} was studied using chronoamperometry and cyclic voltammetry. The first linear section was in the range of 0.1–5 mM with a limit of detection of 0.115 μmol l{sup −1} and the second linear section was raised to 120 mM with a correlation factor of 0.256 μmol l{sup −1} (S/N of 3). Moreover, the sensor presented excellent stability, selectivity, repeatability and reproducibility. These excellent performances make AgNPs-PPy/GCE an ideal nonenzymatic H{sub 2}O{sub 2} sensor.

Nanomaterials for electrochemical sensing and biosensing