WorldWideScience

Sample records for integrated electrochemical detection

  1. Integration of Faradaic electrochemical impedance spectroscopy into a scalable surface plasmon biosensor for in tandem detection.

    Science.gov (United States)

    Hong, Brandon; Sun, Alexander; Pang, Lin; Venkatesh, A G; Hall, Drew; Fainman, Yeshaiahu

    2015-11-16

    We present an integrated label-free biosensor based on surface plasmon resonance (SPR) and Faradaic electrochemical impedance spectroscopy (f-EIS) sensing modalities, for the simultaneous detection of biological analytes. Analyte detection is based on the angular spectroscopy of surface plasmon resonance and the extraction of charge transfer resistance values from reduction-oxidation reactions at the gold surface, as responses to functionalized surface binding events. To collocate the measurement areas and fully integrate the modalities, holographically exposed thin-film gold SPR-transducer gratings are patterned into coplanar electrodes for tandem impedance sensing. Mutual non-interference between plasmonic and electrochemical measurement processes is shown, and using our scalable and compact detection system, we experimentally demonstrate biotinylated surface capture of neutravidin concentrations as low as 10 nM detection, with a 5.5 nM limit of detection.

  2. Fully integrated ready-to-use paper-based electrochemical biosensor to detect nerve agents.

    Science.gov (United States)

    Cinti, Stefano; Minotti, Clarissa; Moscone, Danila; Palleschi, Giuseppe; Arduini, Fabiana

    2017-07-15

    Paper-based microfluidic devices are gaining large popularity because of their uncontested advantages of simplicity, cost-effectiveness, limited necessity of laboratory infrastructure and skilled personnel. Moreover, these devices require only small volumes of reagents and samples, provide rapid analysis, and are portable and disposable. Their combination with electrochemical detection offers additional benefits of high sensitivity, selectivity, simplicity of instrumentation, portability, and low cost of the total system. Herein, we present the first example of an integrated paper-based screen-printed electrochemical biosensor device able to quantify nerve agents. The principle of this approach is based on dual electrochemical measurements, in parallel, of butyrylcholinesterase (BChE) enzyme activity towards butyrylthiocholine with and without exposure to contaminated samples. The sensitivity of this device is largely improved using a carbon black/Prussian Blue nanocomposite as a working electrode modifier. The proposed device allows an entirely reagent-free analysis. A strip of a nitrocellulose membrane, that contains the substrate, is integrated with a paper-based test area that holds a screen-printed electrode and BChE. Paraoxon, chosen as nerve agent simulant, is linearly detected down to 3µg/L. The use of extremely affordable manufacturing techniques provides a rapid, sensitive, reproducible, and inexpensive tool for in situ assessment of nerve agent contamination. This represents a powerful approach for use by non-specialists, that can be easily broadened to other (bio)systems.

  3. Integrated hybrid polystyrene-polydimethylsiloxane device for monitoring cellular release with microchip electrophoresis and electrochemical detection

    Science.gov (United States)

    Johnson, Alicia S.; Mehl, Benjamin T.; Martin, R. Scott

    2015-01-01

    In this work, a polystyrene (PS)-polydimethylsiloxane (PDMS) hybrid device was developed to enable the integration of cell culture with analysis by microchip electrophoresis and electrochemical detection. It is shown that this approach combines the fundamental advantages of PDMS devices (the ability to integrate pumps and valves) and PS devices (the ability to permanently embed fluidic tubing and electrodes). The embedded fused-silica capillary enables high temporal resolution measurements from off-chip cell culture dishes and the embedded electrodes provide close to real-time analysis of small molecule neurotransmitters. A novel surface treatment for improved (reversible) adhesion between PS and PDMS is described using a chlorotrimethylsilane stamping method. It is demonstrated that a Pd decoupler is efficient at handling the high current (and cathodic hydrogen production) resulting from use of high ionic strength buffers needed for cellular analysis; thus allowing an electrophoretic separation and in-channel detection. The separation of norepinephrine (NE) and dopamine (DA) in highly conductive biological buffers was optimized using a mixed surfactant system. This PS-PDMS hybrid device integrates multiple processes including continuous sampling from a cell culture dish, on-chip pump and valving technologies, microchip electrophoresis, and electrochemical detection to monitor neurotransmitter release from PC 12 cells. PMID:25663849

  4. Integrating Electrochemical Detection with Centrifugal Microfluidics for Real-Time and Fully Automated Sample Testing

    DEFF Research Database (Denmark)

    Andreasen, Sune Zoëga; Kwasny, Dorota; Amato, Letizia;

    2015-01-01

    Here we present a robust, stable and low-noise experimental set-up for performing electrochemical detection on a centrifugal microfluidic platform. By using a low-noise electronic component (electrical slip-ring) it is possible to achieve continuous, on-line monitoring of electrochemical experime......Here we present a robust, stable and low-noise experimental set-up for performing electrochemical detection on a centrifugal microfluidic platform. By using a low-noise electronic component (electrical slip-ring) it is possible to achieve continuous, on-line monitoring of electrochemical...

  5. Use of epoxy-embedded electrodes to integrate electrochemical detection with microchip-based analysis systems.

    Science.gov (United States)

    Selimovic, Asmira; Johnson, Alicia S; Kiss, István Z; Martin, R Scott

    2011-04-01

    A new method of fabricating electrodes for microchip devices that involves the use of Teflon molds and a commercially available epoxy to embed electrodes of various sizes and compositions is described. The resulting epoxy base can be polished to generate a fresh electrode and sealed against poly(dimethylsiloxane) (PDMS)-based fluidic structures. Microchip-based flow injection analysis was used to characterize the epoxy-embedded electrodes. It was shown that gold electrodes can be amalgamated with liquid mercury and the resulting mercury/gold electrode is used to selectively detect glutathione from lysed red blood cells. The ability to encapsulate multiple electrode materials of differing compositions enabled the integration of microchip electrophoresis with electrochemical detection. Finally, a unique feature of this approach is that the electrode connection is made from the bottom of the epoxy base. This enables the creation of three-dimensional gold pillar electrodes (65 μm in diameter and 27 μm in height) that can be integrated within a fluidic network. As compared with the use of a flat electrode of a similar diameter, the use of the pillar electrode led to improvements in both the sensitivity (72.1 pA/μM for the pillar versus 4.2 pA/μM for the flat electrode) and limit of detection (20 nM for the pillar versus 600 nM for the flat electrode), with catechol being the test analyte. These epoxy-embedded electrodes hold promise for the creation of inexpensive microfluidic devices that can be used to electrochemically detect biologically important analytes in a manner where the electrodes can be polished and a fresh electrode surface is generated as desired.

  6. Plasma Activation of Integrated Carbon Nanotube Electrodes for Electrochemical Detection of Catechol

    Institute of Scientific and Technical Information of China (English)

    WANG Shenggao; WANG Tao; LI Yanqiong; ZHAO Xiujian; HAN Jianjun; WANG Jianhua

    2007-01-01

    In this study,integrated multi-wall carbon nanotube (MWCNT) electrodes were prepared in the holes of glass directly by microwave plasma chemical vapour deposition (MWPCVD).The electrochemical behaviour of catechol at the integrated MWCNT electrodes was investigated.The oxygen plasma treated CNT electrodes had better electrochemical performance for the analysis of catechol than that of as-synthesized CNT electrodes.Both the as-synthesized CNTs and plasma treated CNTs were characterized by TEM(transmission electron microscopy,XPS(X-ray photoelectron spectroscopy) and Raman spectroscopy.The results revealed that the oxygen plasma activation is an effective method to enhance the electrochemical properties of CNT electrodes.

  7. A mini-electrochemical system integrated micropipet tip and pencil graphite electrode for detection of anticancer drug sensitivity in vitro.

    Science.gov (United States)

    Guo, Xiaoling; Wang, Qian; Li, Jinlian; Cui, Jiwen; Zhou, Shi; Hao, Sue; Wu, Dongmei

    2015-02-15

    Developing a reliable and cost-effective miniaturized electroanalysis tool is of vital importance for cell electrochemical analysis. In this work, a novel mini-electrochemical system has been constructed for trace detection of cell samples. The mini-electrochemical system was constructed by integrating a pencil graphite modified by threonine (PT/PGE) as working electrode, an Ag/AgCl (Sat'd) as reference electrode, platinum wire as counter electrode and a micropipet tip as electrochemical cell. The mini-electrochemical system not only saved dramatically usage of samples from 500 μL in traditional electrochemical system to 10 μL, but also possessed an adjustable active surface area by changing the length of PT/PGE immersed into the cell suspension from 3mm to 15 mm, and the linear equation was ipa = 2.25 l-2.64 (R(2) = 0.990). The system was successfully used in detection of MCF-7 cells, and a nonlinear exponent relationship between peak current and the cell number range from 3.0 × l0(3) to 7.0 × l0(6) cells mL(-1) was established firstly with the index equation ipa = 59.557 e (-C/1.709)-71.486 (R(2) = 0.954). Finally, the system was used for evaluating the sensitivity of cyclophosphamide on MCF-7 cell, and the result was corresponded well with that of MTT assay. The proposed system is sufficiently simple, cheap and easy operated, and could be applied in electrochemical detection of other biological samples.

  8. An integrated electrochemical device based on immunochromatographic test strip and enzyme labels for sensitive detection of disease-related biomarkers

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Zhexiang; Wang, Jun; Wang, Hua; Li, Yao Q.; Lin, Yuehe

    2012-05-30

    A novel electrochemical biosensing device that integrates an immunochromatographic test strip and a screen-printed electrode (SPE) connected to a portable electrochemical analyzer was presented for rapid, sensitive, and quantitative detection of disease-related biomarker in human blood samples. The principle of the sensor is based on sandwich immunoreactions between a biomarker and a pair of its antibodies on the test strip, followed by highly sensitive square-wave voltammetry (SWV) detection. Horseradish peroxidase (HRP) was used as a signal reporter for electrochemical readout. Hepatitis B surface antigen (HBsAg) was employed as a model protein biomarker to demonstrate the analytical performance of the sensor in this study. Some critical parameters governing the performance of the sensor were investigated in detail. The sensor was further utilized to detect HBsAg in human plasma with an average recovery of 91.3%. In comparison, a colorimetric immunochromatographic test strip assay (ITSA) was also conducted. The result shows that the SWV detection in the electrochemical sensor is much more sensitive for the quantitative determination of HBsAg than the colorimetric detection, indicating that such a sensor is a promising platform for rapid and sensitive point-of-care testing/screening of disease-related biomarkers in a large population

  9. Smart Integrated Sensor for Multiple Detections of Glucose and L-Lactate Using On-Chip Electrochemical System

    Directory of Open Access Journals (Sweden)

    Tomoyuki Yamazaki

    2011-01-01

    Full Text Available Multiple sensor electrodes, a supplementary electrode, a reference electrode, and signal-processing circuits were integrated on a single chip to develop a chip-shaped electrochemical sensing system. L-lactate and glucose were measured using on-chip working electrodes modified by polyion complex to immobilize lactate oxidase and glucose oxidase, respectively. Cyclic voltammetry measurements were conducted using an on-chip potentiostat. Selective and quantitative detection of glucose and L-lactate and the interference behavior were studied. Hydrogen peroxide generated by enzymatic reactions was detected by an increase in anodic oxidation current. Reaction currents at +0.7 V versus Ag/AgCl were used to obtain calibration plots. The measured dynamic ranges for L-lactate and glucose were 0.2–1.0 mM and 2.0–8.0 mM, respectively. The sensitivities were 65 nA/mM and 15 nA/mM, respectively, using a working electrode of 0.5 mm2. The 3σ detection limit was 0.19 mM and 1.1 mM, respectively. We have achieved multiple biomaterial detections on a circuit-equipped single chip. This integrated electrochemical sensor chip could be the best candidate for realizing point-of-care testing due to its portability and potential for mass production.

  10. Integrating Paper Chromatography with Electrochemical Detection for the Trace Analysis of TNT in Soil

    Directory of Open Access Journals (Sweden)

    Patrick Ryan

    2015-07-01

    Full Text Available We report on the development of an electrochemical probe for the trace analysis of 2,4,6-trinitrotoluene (TNT in soil samples. The probe is a combination of graphite electrodes, filter paper, with ethylene glycol and choline chloride as the solvent/electrolyte. Square wave chromatovoltammograms show the probes have a sensitivity for TNT of 0.75 nA/ng and a limit of detection of 100 ng. In addition, by taking advantage of the inherent paper chromatography step, TNT can be separated in both time and cathodic peak potential from 4-amino-dinitrotolene co-spotted on the probe or in soil samples with the presence of methyl parathion as a possible interferent.

  11. Integrating Paper Chromatography with Electrochemical Detection for the Trace Analysis of TNT in Soil.

    Science.gov (United States)

    Ryan, Patrick; Zabetakis, Daniel; Stenger, David A; Trammell, Scott A

    2015-07-14

    We report on the development of an electrochemical probe for the trace analysis of 2,4,6-trinitrotoluene (TNT) in soil samples. The probe is a combination of graphite electrodes, filter paper, with ethylene glycol and choline chloride as the solvent/electrolyte. Square wave chromatovoltammograms show the probes have a sensitivity for TNT of 0.75 nA/ng and a limit of detection of 100 ng. In addition, by taking advantage of the inherent paper chromatography step, TNT can be separated in both time and cathodic peak potential from 4-amino-dinitrotolene co-spotted on the probe or in soil samples with the presence of methyl parathion as a possible interferent.

  12. Clinical validation of integrated nucleic acid and protein detection on an electrochemical biosensor array for urinary tract infection diagnosis.

    Directory of Open Access Journals (Sweden)

    Ruchika Mohan

    Full Text Available BACKGROUND: Urinary tract infection (UTI is a common infection that poses a substantial healthcare burden, yet its definitive diagnosis can be challenging. There is a need for a rapid, sensitive and reliable analytical method that could allow early detection of UTI and reduce unnecessary antibiotics. Pathogen identification along with quantitative detection of lactoferrin, a measure of pyuria, may provide useful information towards the overall diagnosis of UTI. Here, we report an integrated biosensor platform capable of simultaneous pathogen identification and detection of urinary biomarker that could aid the effectiveness of the treatment and clinical management. METHODOLOGY/PRINCIPAL FINDINGS: The integrated pathogen 16S rRNA and host lactoferrin detection using the biosensor array was performed on 113 clinical urine samples collected from patients at risk for complicated UTI. For pathogen detection, the biosensor used sandwich hybridization of capture and detector oligonucleotides to the target analyte, bacterial 16S rRNA. For detection of the protein biomarker, the biosensor used an analogous electrochemical sandwich assay based on capture and detector antibodies. For this assay, a set of oligonucleotide probes optimized for hybridization at 37°C to facilitate integration with the immunoassay was developed. This probe set targeted common uropathogens including E. coli, P. mirabilis, P. aeruginosa and Enterococcus spp. as well as less common uropathogens including Serratia, Providencia, Morganella and Staphylococcus spp. The biosensor assay for pathogen detection had a specificity of 97% and a sensitivity of 89%. A significant correlation was found between LTF concentration measured by the biosensor and WBC and leukocyte esterase (p<0.001 for both. CONCLUSION/SIGNIFICANCE: We successfully demonstrate simultaneous detection of nucleic acid and host immune marker on a single biosensor array in clinical samples. This platform can be used for

  13. Integrated circuit-based electrochemical sensor for spatially resolved detection of redox-active metabolites in biofilms.

    Science.gov (United States)

    Bellin, Daniel L; Sakhtah, Hassan; Rosenstein, Jacob K; Levine, Peter M; Thimot, Jordan; Emmett, Kevin; Dietrich, Lars E P; Shepard, Kenneth L

    2014-01-01

    Despite advances in monitoring spatiotemporal expression patterns of genes and proteins with fluorescent probes, direct detection of metabolites and small molecules remains challenging. A technique for spatially resolved detection of small molecules would benefit the study of redox-active metabolites that are produced by microbial biofilms and can affect their development. Here we present an integrated circuit-based electrochemical sensing platform featuring an array of working electrodes and parallel potentiostat channels. 'Images' over a 3.25 × 0.9 mm(2) area can be captured with a diffusion-limited spatial resolution of 750 μm. We demonstrate that square wave voltammetry can be used to detect, identify and quantify (for concentrations as low as 2.6 μM) four distinct redox-active metabolites called phenazines. We characterize phenazine production in both wild-type and mutant Pseudomonas aeruginosa PA14 colony biofilms, and find correlations with fluorescent reporter imaging of phenazine biosynthetic gene expression.

  14. Integrated circuit-based electrochemical sensor for spatially resolved detection of redox-active metabolites in biofilms

    Science.gov (United States)

    Bellin, Daniel L.; Sakhtah, Hassan; Rosenstein, Jacob K.; Levine, Peter M.; Thimot, Jordan; Emmett, Kevin; Dietrich, Lars E. P.; Shepard, Kenneth L.

    2014-01-01

    Despite advances in monitoring spatiotemporal expression patterns of genes and proteins with fluorescent probes, direct detection of metabolites and small molecules remains challenging. A technique for spatially resolved detection of small molecules would benefit the study of redox-active metabolites produced by microbial biofilms, which can drastically affect colony development. Here we present an integrated circuit-based electrochemical sensing platform featuring an array of working electrodes and parallel potentiostat channels. “Images” over a 3.25 × 0.9 mm area can be captured with a diffusion-limited spatial resolution of 750 μm. We demonstrate that square wave voltammetry can be used to detect, identify, and quantify (for concentrations as low as 2.6 μM) four distinct redox-active metabolites called phenazines. We characterize phenazine production in both wild-type and mutant Pseudomonas aeruginosa PA14 colony biofilms, and find correlations with fluorescent reporter imaging of phenazine biosynthetic gene expression. PMID:24510163

  15. Integrating Electrochemical Detection with Centrifugal Microfluidics for Real-Time and Fully Automated Sample Testing

    DEFF Research Database (Denmark)

    Andreasen, Sune Zoëga; Kwasny, Dorota; Amato, Letizia

    2015-01-01

    experiments, even when the microfluidic disc is spinning at high velocities. Automated sample handling is achieved by designing a microfluidic system to release analyte sequentially, utilizing on-disc passive valving. In addition, the microfluidic system is designed to trap and keep the liquid sample...... stationary during analysis. In this way it is possible to perform cyclic voltammetry (CV) measurements at varying spin speeds, without altering the electrochemical response. This greatly simplifies the interpretation and quantification of data. Finally, real-time and continuous monitoring of an entire...

  16. Real-time, multiplexed electrochemical DNA detection using an active complementary metal-oxide-semiconductor biosensor array with integrated sensor electronics.

    Science.gov (United States)

    Levine, Peter M; Gong, Ping; Levicky, Rastislav; Shepard, Kenneth L

    2009-03-15

    Optical biosensing based on fluorescence detection has arguably become the standard technique for quantifying extents of hybridization between surface-immobilized probes and fluorophore-labeled analyte targets in DNA microarrays. However, electrochemical detection techniques are emerging which could eliminate the need for physically bulky optical instrumentation, enabling the design of portable devices for point-of-care applications. Unlike fluorescence detection, which can function well using a passive substrate (one without integrated electronics), multiplexed electrochemical detection requires an electronically active substrate to analyze each array site and benefits from the addition of integrated electronic instrumentation to further reduce platform size and eliminate the electromagnetic interference that can result from bringing non-amplified signals off chip. We report on an active electrochemical biosensor array, constructed with a standard complementary metal-oxide-semiconductor (CMOS) technology, to perform quantitative DNA hybridization detection on chip using targets conjugated with ferrocene redox labels. A 4 x 4 array of gold working electrodes and integrated potentiostat electronics, consisting of control amplifiers and current-input analog-to-digital converters, on a custom-designed 5 mm x 3 mm CMOS chip drive redox reactions using cyclic voltammetry, sense DNA binding, and transmit digital data off chip for analysis. We demonstrate multiplexed and specific detection of DNA targets as well as real-time monitoring of hybridization, a task that is difficult, if not impossible, with traditional fluorescence-based microarrays.

  17. Label-free Detection of Influenza Viruses using a Reduced Graphene Oxide-based Electrochemical Immunosensor Integrated with a Microfluidic Platform

    Science.gov (United States)

    Singh, Renu; Hong, Seongkyeol; Jang, Jaesung

    2017-02-01

    Reduced graphene oxide (RGO) has recently gained considerable attention for use in electrochemical biosensing applications due to its outstanding conducting properties and large surface area. This report presents a novel microfluidic chip integrated with an RGO-based electrochemical immunosensor for label-free detection of an influenza virus, H1N1. Three microelectrodes were fabricated on a glass substrate using the photolithographic technique, and the working electrode was functionalized using RGO and monoclonal antibodies specific to the virus. These chips were integrated with polydimethylsiloxane microchannels. Structural and morphological characterizations were performed using X-ray photoelectron spectroscopy and scanning electron microscopy. Electrochemical studies revealed good selectivity and an enhanced detection limit of 0.5 PFU mL-1, where the chronoamperometric current increased linearly with H1N1 virus concentration within the range of 1 to 104 PFU mL-1 (R2 = 0.99). This microfluidic immunosensor can provide a promising platform for effective detection of biomolecules using minute samples.

  18. Label-free Detection of Influenza Viruses using a Reduced Graphene Oxide-based Electrochemical Immunosensor Integrated with a Microfluidic Platform

    Science.gov (United States)

    Singh, Renu; Hong, Seongkyeol; Jang, Jaesung

    2017-01-01

    Reduced graphene oxide (RGO) has recently gained considerable attention for use in electrochemical biosensing applications due to its outstanding conducting properties and large surface area. This report presents a novel microfluidic chip integrated with an RGO-based electrochemical immunosensor for label-free detection of an influenza virus, H1N1. Three microelectrodes were fabricated on a glass substrate using the photolithographic technique, and the working electrode was functionalized using RGO and monoclonal antibodies specific to the virus. These chips were integrated with polydimethylsiloxane microchannels. Structural and morphological characterizations were performed using X-ray photoelectron spectroscopy and scanning electron microscopy. Electrochemical studies revealed good selectivity and an enhanced detection limit of 0.5 PFU mL−1, where the chronoamperometric current increased linearly with H1N1 virus concentration within the range of 1 to 104 PFU mL−1 (R2 = 0.99). This microfluidic immunosensor can provide a promising platform for effective detection of biomolecules using minute samples. PMID:28198459

  19. Integration of a Graphite/PMMA CompositeElectrode into a Poly(methyl methacrylate) (PMMA) Substrate for Electrochemical Detection in Microchips

    Science.gov (United States)

    Regel, Anne; Lunte, Susan

    2013-01-01

    Traditional fabrication methods for polymer microchips, the bonding of two substrates together to form the microchip, can make the integration of carbon electrodes difficult. We have developed a simple and inexpensive method to integrate graphite/PMMA composite electrodes (GPCEs) into a PMMA substrate. These substrates can be bonded to other PMMA layers using a solvent-assisted thermal bonding method. The optimal composition of the GPCEs for electrochemical detection was determined using cyclic voltammetry with dopamine as a test analyte. Using the optimized GPCEs in an all-PMMA flow cell with flow injection analysis, it was possible to detect 50 nM dopamine under the best conditions. These electrodes were also evaluated for the detection of dopamine and catechol following separation by microchip electrophoresis (ME). PMID:23670816

  20. Integration of a graphite/poly(methyl-methacrylate) composite electrode into a poly(methylmethacrylate) substrate for electrochemical detection in microchips.

    Science.gov (United States)

    Regel, Anne; Lunte, Susan

    2013-07-01

    Traditional fabrication methods for polymer microchips, the bonding of two substrates together to form the microchip, can make the integration of carbon electrodes difficult. We have developed a simple and inexpensive method to integrate graphite/PMMA composite electrodes (GPCEs) into a PMMA substrate. These substrates can be bonded to other PMMA layers using a solvent-assisted thermal bonding method. The optimal composition of the GPCEs for electrochemical detection was determined using cyclic voltammetry with dopamine as a test analyte. Using the optimized GPCEs in an all-PMMA flow cell with flow injection analysis, it was possible to detect 50 nM dopamine under the best conditions. These electrodes were also evaluated for the detection of dopamine and catechol following separation by MCE.

  1. Single-molecule detection in electrochemical nanogap devices

    NARCIS (Netherlands)

    Kang, Shuo

    2014-01-01

    This thesis presents results obtained during a research project aimed at realizing electrochemical single-molecule detection in water. By virtue of being inherently electrical in nature, electrochemical sensors are particularly well suited for integration with microelectronics compared to sensors ba

  2. 滤纸微流控设备集成电化学检测%Integration of Paper - based Microfluidic Devices with Electrochemical Detection

    Institute of Scientific and Technical Information of China (English)

    唐帆; 邢宏龙; 毕连花; 郑虎祥; 王伟

    2012-01-01

    近年来,人们发现滤纸微流控设备相比于传统的微流控设备来说具有一次性使用、制作简单且成本更低的优点。简单综述了微流控设备的发展现状以及滤纸和电化学检测的相关特点,着重阐明了滤纸在微流控电化学检测中的应用,同时与商品化的检测仪相结合,为微流控设备未来商品化打下了坚实的基础。%Paper - based microfluidic devices are found that they are disposable, easy - to - fabricate, and lower - cost compared to traditional microfluidic devices. This paper presented an overview on the present state of microtluidic devices and the related characteristics of filter paper and electrochemical detection. Filter paper applicated in microfluidie devices coupled with electro- chemical detection is mainly introduced. Meanwhile, the integration of commercial detector will establish a firm foundation for the commercialization of microfluidic devices in the future.

  3. Real-time, multiplexed electrochemical DNA detection using an active complementary metal-oxide-semiconductor biosensor array with integrated sensor electronics

    OpenAIRE

    2008-01-01

    Optical biosensing based on fluorescence detection has arguably become the standard technique for quantifying extents of hybridization between surface-immobilized probes and fluorophore-labeled analyte targets in DNA microarrays. However, electrochemical detection techniques are emerging which could eliminate the need for physically bulky optical instrumentation, enabling the design of portable devices for point-of-care applications. Unlike fluorescence detection, which can function well usin...

  4. Highly selective and sensitive electrochemical biosensor for ATP based on the dual strategy integrating the cofactor-dependent enzymatic ligation reaction with self-cleaving DNAzyme-amplified electrochemical detection.

    Science.gov (United States)

    Lu, Lu; Si, Jing Cao; Gao, Zhong Feng; Zhang, Yu; Lei, Jing Lei; Luo, Hong Qun; Li, Nian Bing

    2015-01-15

    A dual strategy that combines the adenosine triphosphate (ATP)-dependent enzymatic ligation reaction with self-cleaving DNAzyme-amplified electrochemical detection is employed to construct the biosensor. In this design, the methylene blue-labeled hairpin-structured DNA was self-assembled onto a gold electrode surface to prepare the modified electrode through the interaction of Au-S bond. In the procedure of ATP-dependent ligation reaction, when the specific cofactor ATP was added, the two split oligonucleotide fragments of 8-17 DNAzyme were linked by T4 DNA ligase and then released to hybridize with the labeled hairpin-structured DNA substrate. The linked 8-17 DNAzyme catalyzes the cleavage of the hairpin-structured substrate by the addition of Zn(2+), causing the methylene blue which contains high electrochemical activity to leave the surface of the gold electrode, therefore generating a dramatic decrease of electrochemical signal. The decrease of peak current was readily measured by square wave voltammetry and a relatively low detection limit (0.05 nM) was obtained with a linear response range from 0.1 to 1000 nM. By taking advantage of the highly specific cofactor dependence of the DNA ligation reaction, the proposed ligation-induced DNAzyme cascades demonstrate ultrahigh selectivity toward the target cofactor ATP. A catalytic and molecular beacons strategy is further adopted to amplify the electrochemical signal detection achieved by cycling and regenerating the 8-17 DNAzyme to realize enzymatic multiple turnover, thus one DNAzyme can catalyze the cleavage of several hairpin-structured substrates, which improves the sensitivity of the newly designed electrochemical sensing system.

  5. Exonuclease I-aided homogeneous electrochemical strategy for organophosphorus pesticide detection based on enzyme inhibition integrated with a DNA conformational switch.

    Science.gov (United States)

    Wang, Xiuzhong; Dong, Shanshan; Hou, Ting; Liu, Lei; Liu, Xiaojuan; Li, Feng

    2016-03-07

    A novel enzyme inhibition-based homogeneous electrochemical biosensing strategy was designed for an organophosphorus pesticide assay based on exploiting the resistance of a mercury ion-mediated helper probe (HP) toward nuclease-catalyzed digestion and the remarkable diffusivity difference between HPs and the mononucleotides toward a negatively charged indium tin oxide (ITO) electrode. In particular, the mercury ion-mediated T-Hg(2+)-T base pairs facilitate the HP labeled with methylene blue (MB) to fold into a hairpin structure, preventing its digestion by exonuclease I, and thus resulting in a low electrochemical response because of the large electrostatic repulsion between the negatively charged ITO electrode and the HPs. The competitive binding by a thiol group (-SH), produced in the hydrolysis reaction of acetylthiocholine (ACh) chloride with acetylcholinesterase (AChE), removes mercury ions from the base pairs, causing a nuclease-catalyzed digestion, and the subsequent electrochemical response increase due to the weak electrostatic repulsion between the product-mononucleotides and the ITO electrode. Mercury ion-mediated HPs were first designed for pesticide detection and diazinon was chosen as the model target. Under the optimal experimental conditions, the approach exhibited high sensitivity for diazinon detection with a detection limit of 0.25 μg L(-1). The satisfactory results in the determination of diazinon in real samples demonstrate that the method possesses great potential for detecting organophosphorus pesticides. This new approach is expected to promote the exploitation of mercury-mediated base pair-based homogenous electrochemical biosensors in biochemical studies and in the food safety field.

  6. Zeptomole electrochemical detection of metallothioneins.

    Directory of Open Access Journals (Sweden)

    Vojtech Adam

    Full Text Available BACKGROUND: Thiol-rich peptides and proteins possess a large number of biological activities and may serve as markers for numerous health problems including cancer. Metallothionein (MT, a small molecular mass protein rich in cysteine, may be considered as one of the promising tumour markers. The aim of this paper was to employ chronopotentiometric stripping analysis (CPSA for highly sensitive detection of MT. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we used adsorptive transfer stripping technique coupled with CPSA for detection of cysteine, glutathione oxidized and reduced, phytochelatin, bovine serum albumin, and metallothionein. Under the optimal conditions, we were able to estimate detection limits down to tens of fg per ml. Further, this method was applied to detect metallothioneins in blood serum obtained from patients with breast cancer and in neuroblastoma cells resistant and sensitive to cisplatin in order to show the possible role of metallothioneins in carcinogenesis. It was found that MT level in blood serum was almost twice higher as compared to the level determined in healthy individuals. CONCLUSIONS/SIGNIFICANCE: This paper brings unique results on the application of ultra-sensitive electroanalytical method for metallothionein detection. The detection limit and other analytical parameters are the best among the parameters of other techniques. In spite of the fact that the paper is mainly focused on metallothionein, it is worth mentioning that successful detection of other biologically important molecules is possible by this method. Coupling of this method with simple isolation methods such as antibody-modified paramagnetic particles may be implemented to lab-on-chip instrument.

  7. Nitroaromatic explosives detection using electrochemically exfoliated graphene

    Science.gov (United States)

    Yew, Ying Teng; Ambrosi, Adriano; Pumera, Martin

    2016-09-01

    Detection of nitroaromatic explosives is of paramount importance from security point of view. Graphene sheets obtained from the electrochemical anodic exfoliation of graphite foil in different electrolytes (LiClO4 and Na2SO4) were compared and tested as electrode material for the electrochemical detection of 2,4-dinitrotoluene (DNT) and 2,4,6-trinitrotoluene (TNT) in seawater. Voltammetry analysis demonstrated the superior electrochemical performance of graphene produced in LiClO4, resulting in higher sensitivity and linearity for the explosives detection and lower limit of detection (LOD) compared to the graphene obtained in Na2SO4. We attribute this to the presence of oxygen functionalities onto the graphene material obtained in LiClO4 which enable charge electrostatic interactions with the –NO2 groups of the analyte, in addition to π-π stacking interactions with the aromatic moiety. Research findings obtained from this study would assist in the development of portable devices for the on-site detection of nitroaromatic explosives.

  8. Trace Detection of Pentaerythritol Tetranitrate Using Electrochemical Gas Sensors

    OpenAIRE

    2014-01-01

    Selective and sensitive detection of trace amounts of pentaerythritol tetranitrate (PETN) is demonstrated. The screening system is based on a sampling/concentrator front end and electrochemical potentiometric gas sensor as the detector. A single sensor is operated in the dominant hydrocarbon (HC) and nitrogen oxides (NOx) mode by varying the sensor operating condition. The potentiometric sensor with integrated heaters was used to capture the signature of PETN. Quantitative measurements based ...

  9. Integrated Magneto-Electrochemical Sensor for Exosome Analysis.

    Science.gov (United States)

    Jeong, Sangmoo; Park, Jongmin; Pathania, Divya; Castro, Cesar M; Weissleder, Ralph; Lee, Hakho

    2016-02-23

    Extracellular vesicles, including exosomes, are nanoscale membrane particles that carry molecular information on parental cells. They are being pursued as biomarkers of cancers that are difficult to detect or serially follow. Here we present a compact sensor technology for rapid, on-site exosome screening. The sensor is based on an integrated magneto-electrochemical assay: exosomes are immunomagnetically captured from patient samples and profiled through electrochemical reaction. By combining magnetic enrichment and enzymatic amplification, the approach enables (i) highly sensitive, cell-specific exosome detection and (ii) sensor miniaturization and scale-up for high-throughput measurements. As a proof-of-concept, we implemented a portable, eight-channel device and applied it to screen extracellular vesicles in plasma samples from ovarian cancer patients. The sensor allowed for the simultaneous profiling of multiple protein markers within an hour, outperforming conventional methods in assay sensitivity and speed.

  10. Integrated Computational System for Electrochemical Device Design and Simulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Illinois Rocstar LLC proposes to develop and demonstrate the use of an integrated computational environment and infrastructure for electrochemical device design and...

  11. Lab-on-CMOS integration of microfluidics and electrochemical sensors.

    Science.gov (United States)

    Huang, Yue; Mason, Andrew J

    2013-10-07

    This paper introduces a CMOS-microfluidics integration scheme for electrochemical microsystems. A CMOS chip was embedded into a micro-machined silicon carrier. By leveling the CMOS chip and carrier surface to within 100 nm, an expanded obstacle-free surface suitable for photolithography was achieved. Thin film metal planar interconnects were microfabricated to bridge CMOS pads to the perimeter of the carrier, leaving a flat and smooth surface for integrating microfluidic structures. A model device containing SU-8 microfluidic mixers and detection channels crossing over microelectrodes on a CMOS integrated circuit was constructed using the chip-carrier assembly scheme. Functional integrity of microfluidic structures and on-CMOS electrodes was verified by a simultaneous sample dilution and electrochemical detection experiment within multi-channel microfluidics. This lab-on-CMOS integration process is capable of high packing density, is suitable for wafer-level batch production, and opens new opportunities to combine the performance benefits of on-CMOS sensors with lab-on-chip platforms.

  12. Recent developments in electrochemical detection for microchip capillary electrophoresis.

    Science.gov (United States)

    Vandaveer, Walter R; Pasas-Farmer, Stephanie A; Fischer, David J; Frankenfeld, Celeste N; Lunte, Susan M

    2004-11-01

    Significant progress in the development of miniaturized microfluidic systems has occurred since their inception over a decade ago. This is primarily due to the numerous advantages of microchip analysis, including the ability to analyze minute samples, speed of analysis, reduced cost and waste, and portability. This review focuses on recent developments in integrating electrochemical (EC) detection with microchip capillary electrophoresis (CE). These detection modes include amperometry, conductimetry, and potentiometry. EC detection is ideal for use with microchip CE systems because it can be easily miniaturized with no diminution in analytical performance. Advances in microchip format, electrode material and design, decoupling of the detector from the separation field, and integration of sample preparation, separation, and detection on-chip are discussed. Microchip CEEC applications for enzyme/immunoassays, clinical and environmental assays, as well as the detection of neurotransmitters are also described.

  13. Electrode substrate innovation for electrochemical detection in microchip electrophoresis.

    Science.gov (United States)

    Randviir, Edward P; Banks, Craig E

    2015-08-01

    Microchip electrophoresis (MCE) represents the next generation of miniaturised electrophoretic devices and carry benefits such as significant improvement in analysis times, lower consumption of reagents and samples, flexibility and procedural simplicity. The devices provide a separation method for complex sample matrices and an on-board detection method for the analytical determination of a target compound. The detection part of MCE is increasingly leaning towards electrochemical methods, thus the selectivity and sensitivity of detection in MCE is dependent upon the chosen working electrode composition in addition to operating conditions of the chip such as separation voltage. Given the current plethora of electrode materials that are available, there exists a possibility to creatively integrate electrodes into MCE. This review will overview the application of several electrode materials, from the old through to the new. A particular recent focus has been the selectivity element of MCEs overcome with the use of enzymes, carbon composites and screen-printed technologies.

  14. Electrochemical Detection of Multiple Bioprocess Analytes

    Science.gov (United States)

    Rauh, R. David

    2010-01-01

    An apparatus that includes highly miniaturized thin-film electrochemical sensor array has been demonstrated as a prototype of instruments for simultaneous detection of multiple substances of interest (analytes) and measurement of acidity or alkalinity in bioprocess streams. Measurements of pH and of concentrations of nutrients and wastes in cell-culture media, made by use of these instruments, are to be used as feedback for optimizing the growth of cells or the production of desired substances by the cultured cells. The apparatus is designed to utilize samples of minimal volume so as to minimize any perturbation of monitored processes. The apparatus can function in a potentiometric mode (for measuring pH), an amperometric mode (detecting analytes via oxidation/reduction reactions), or both. The sensor array is planar and includes multiple thin-film microelectrodes covered with hydrous iridium oxide. The oxide layer on each electrode serves as both a protective and electrochemical transducing layer. In its transducing role, the oxide provides electrical conductivity for amperometric measurement or pH response for potentiometric measurement. The oxide on an electrode can also serve as a matrix for one or more enzymes that render the electrode sensitive to a specific analyte. In addition to transducing electrodes, the array includes electrodes for potential control. The array can be fabricated by techniques familiar to the microelectronics industry. The sensor array is housed in a thin-film liquid-flow cell that has a total volume of about 100 mL. The flow cell is connected to a computer-controlled subsystem that periodically draws samples from the bioprocess stream to be monitored. Before entering the cell, each 100-mL sample is subjected to tangential-flow filtration to remove particles. In the present version of the apparatus, the electrodes are operated under control by a potentiostat and are used to simultaneously measure the pH and the concentration of glucose

  15. In-channel electrochemical detection in the middle of microchannel under high electric field.

    Science.gov (United States)

    Kang, Chung Mu; Joo, Segyeong; Bae, Je Hyun; Kim, Yang-Rae; Kim, Yongseong; Chung, Taek Dong

    2012-01-17

    We propose a new method for performing in-channel electrochemical detection under a high electric field using a polyelectrolytic gel salt bridge (PGSB) integrated in the middle of the electrophoretic separation channel. The finely tuned placement of a gold working electrode and the PGSB on an equipotential surface in the microchannel provided highly sensitive electrochemical detection without any deterioration in the separation efficiency or interference of the applied electric field. To assess the working principle, the open circuit potentials between gold working electrodes and the reference electrode at varying distances were measured in the microchannel under electrophoretic fields using an electrically isolated potentiostat. In addition, "in-channel" cyclic voltammetry confirmed the feasibility of electrochemical detection under various strengths of electric fields (∼400 V/cm). Effective separation on a microchip equipped with a PGSB under high electric fields was demonstrated for the electrochemical detection of biological compounds such as dopamine and catechol. The proposed "in-channel" electrochemical detection under a high electric field enables wider electrochemical detection applications in microchip electrophoresis.

  16. Thin film microelectrodes for electrochemical detection of neurotransmitters

    DEFF Research Database (Denmark)

    Larsen, Simon Tylsgaard

    An important signaling process in the nervous system is the release of chemical messengers called neurotransmitters from neurons. In this thesis alternative thin film electrode materials for applications targeting electrochemical detection of neurotransmitters in chip devices were evaluated...

  17. Trace Detection of Pentaerythritol Tetranitrate Using Electrochemical Gas Sensors

    Directory of Open Access Journals (Sweden)

    Praveen K. Sekhar

    2014-01-01

    Full Text Available Selective and sensitive detection of trace amounts of pentaerythritol tetranitrate (PETN is demonstrated. The screening system is based on a sampling/concentrator front end and electrochemical potentiometric gas sensor as the detector. A single sensor is operated in the dominant hydrocarbon (HC and nitrogen oxides (NOx mode by varying the sensor operating condition. The potentiometric sensor with integrated heaters was used to capture the signature of PETN. Quantitative measurements based on hydrocarbon and nitrogen oxide sensor responses indicated that the detector sensitivity scaled proportionally with the mass of the explosives (10 μg down to 200 ng. The ratio of the HC integrated peak area to the NOx integrated peak area is identified as an indicator of selectivity. The HC/NOx ratio is unique for PETN and has a range from 1.7 to 2.7. This detection technique has the potential to become an orthogonal technique to the existing explosive screening technologies for reducing the number of false positives/false negatives in a cost-effective manner.

  18. Electrochemical microfluidic biosensor for the detection of nucleic acid sequences.

    Science.gov (United States)

    Goral, Vasiliy N; Zaytseva, Natalya V; Baeumner, Antje J

    2006-03-01

    A microfluidic biosensor with electrochemical detection for the quantification of nucleic acid sequences was developed. In contrast to most microbiosensors that are based on fluorescence for signal generation, it takes advantage of the simplicity and high sensitivity provided by an amperometric and coulorimetric detection system. An interdigitated ultramicroelectrode array (IDUA) was fabricated in a glass chip and integrated directly with microchannels made of poly(dimethylsiloxane) (PDMS). The assembly was packaged into a Plexiglas housing providing fluid and electrical connections. IDUAs were characterized amperometrically and using cyclic voltammetry with respect to static and dynamic responses for the presence of a reversible redox couple-potassium hexacyanoferrate (ii)/hexacyanoferrate (iii) (ferri/ferrocyanide). A combined concentration of 0.5 microM of ferro/ferricyanide was determined as lower limit of detection with a dynamic range of 5 orders of magnitude. Background signals were negligible and the IDUA responded in a highly reversible manner to the injection of various volumes and various concentrations of the electrochemical marker. For the detection of nucleic acid sequences, liposomes entrapping the electrochemical marker were tagged with a DNA probe, and superparamagnetic beads were coated with a second DNA probe. A single stranded DNA target sequence hybridized with both probes. The sandwich was captured in the microfluidic channel just upstream of the IDUA via a magnet located in the outside housing. Liposomes were lysed using a detergent and the amount of released ferro/ferricyanide was quantified while passing by the IDUA. Optimal location of the magnet with respect to the IDUA was investigated, the effect of dextran sulfate on the hybridization reaction was studied and the amount of magnetic beads used in the assay was optimized. A dose response curve using varying concentrations of target DNA molecules was carried out demonstrating a limit of

  19. Electrochemical flow injection analysis of hydrazine in an excess of an active pharmaceutical ingredient: achieving pharmaceutical detection limits electrochemically.

    Science.gov (United States)

    Channon, Robert B; Joseph, Maxim B; Bitziou, Eleni; Bristow, Anthony W T; Ray, Andrew D; Macpherson, Julie V

    2015-10-06

    The quantification of genotoxic impurities (GIs) such as hydrazine (HZ) is of critical importance in the pharmaceutical industry in order to uphold drug safety. HZ is a particularly intractable GI and its detection represents a significant technical challenge. Here, we present, for the first time, the use of electrochemical analysis to achieve the required detection limits by the pharmaceutical industry for the detection of HZ in the presence of a large excess of a common active pharmaceutical ingredient (API), acetaminophen (ACM) which itself is redox active, typical of many APIs. A flow injection analysis approach with electrochemical detection (FIA-EC) is utilized, in conjunction with a coplanar boron doped diamond (BDD) microband electrode, insulated in an insulating diamond platform for durability and integrated into a two piece flow cell. In order to separate the electrochemical signature for HZ such that it is not obscured by that of the ACM (present in excess), the BDD electrode is functionalized with Pt nanoparticles (NPs) to significantly shift the half wave potential for HZ oxidation to less positive potentials. Microstereolithography was used to fabricate flow cells with defined hydrodynamics which minimize dispersion of the analyte and optimize detection sensitivity. Importantly, the Pt NPs were shown to be stable under flow, and a limit of detection of 64.5 nM or 0.274 ppm for HZ with respect to the ACM, present in excess, was achieved. This represents the first electrochemical approach which surpasses the required detection limits set by the pharmaceutical industry for HZ detection in the presence of an API and paves the wave for online analysis and application to other GI and API systems.

  20. HME powder detection using space sampling and electrochemical sensors

    Science.gov (United States)

    Cagan, Avi; Wang, Joseph; Cizek, Karel; Lu, Donglai; La Belle, Jeffrey

    2009-05-01

    A new concept for effective sampling and detecting HME powder traces is described. The collection is based on the particles mobility under rotation into an accumulation collector unit, followed by sequential transfer to the electrochemical detection system where surface washing yields a higher concentration at room temperature. The electrochemical detection of the peroxide explosives is based on photochemical degradation or acid treatment resulting in hydrogen peroxide which is sensed by a Prussian-blue (PB) modified strip electrode at a low potential. Nitrates such as Urea Nitrate are detected using unique reactions which generate one product which has a specific electrochemical signature. Nitroaromatics, nitramines and nitroesters are detected. The new "Add and Detect" procedure is operator independent and is the safest as the operator.

  1. Gold Cleaning Methods for Electrochemical Detection Applications

    DEFF Research Database (Denmark)

    Fischer, Lee MacKenzie; Tenje, Maria; Heiskanen, Arto

    2009-01-01

    ; hydrochloric acid potential cycling; dimethylamine borane reducing agent solutions at 25 and 65 degrees C; and a dilute form of Aqua Regia. Peak-current potential-differences obtained from cyclic voltammetry and charge transfer resistance obtained from electrochemical impedance spectroscopy, as well as X...

  2. Quantitative Label-Free Cell Proliferation Tracking with a Versatile Electrochemical Impedance Detection Platform

    DEFF Research Database (Denmark)

    Caviglia, Claudia; Carminati, M; Heiskanen, Arto

    2012-01-01

    optimal detection strategies. Electrochemical Impedance Spectroscopy (EIS) has been used to monitor and compare adhesion of different cell lines. HeLa cells and 3T3 fibroblasts have been cultured for 12 hours on interdigitated electrode arrays integrated into a tailor-made cell culture platform. Both...

  3. Mass spectrometric detection of short-lived drug metabolites generated in an electrochemical microfluidic chip.

    Science.gov (United States)

    van den Brink, Floris T G; Büter, Lars; Odijk, Mathieu; Olthuis, Wouter; Karst, Uwe; van den Berg, Albert

    2015-02-03

    The costs of drug development have been rising exponentially over the last six decades, making it essential to select drug candidates in the early drug discovery phases before proceeding to expensive clinical trials. Here, we present novel screening methods using an electrochemical chip coupled online to mass spectrometry (MS) or liquid chromatography (LC) and MS, to generate phase I and phase II drug metabolites and to demonstrate protein modification by reactive metabolites. The short transit time (∼4.5 s) between electrochemical oxidation and mass spectrometric detection, enabled by an integrated electrospray emitter, allows us to detect a short-lived radical metabolite of chlorpromazine which is too unstable to be detected using established test routines. In addition, a fast way to screen candidate drugs is established by recording real-time mass voltammograms, which allows one to identify the drug metabolites that are expected to be formed upon oxidation by applying a linear potential sweep and simultaneously detect oxidation products. Furthermore, detoxification of electrochemically generated reactive metabolites of paracetamol was mimicked by their adduct formation with the antioxidant glutathione. Finally, the potential toxicity of reactive metabolites can be investigated by the modification of proteins, which was demonstrated by modification of carbonic anhydrase I with electrochemically generated reactive metabolites of paracetamol. With this series of experiments, we demonstrate the potential of this electrochemical chip as a complementary tool for a variety of drug metabolism studies in the early stages of drug discovery.

  4. Electrochemical detection of telomeric quadruplex DNA using ferrocenyl naphthalene diimide.

    Science.gov (United States)

    Sato, Shinobu; Kondo, Hiroki; Nojima, Takahiko; Takenaka, Shigeori

    2005-01-01

    Ferrocenylnaphthalene diimide (FND) could strongly bind to the synthetic telomere DNA, 5'-CAT GGT GGT TTG GGT TAG GGT TAG GGT TAG GGT TAC CAC-3', at 0.1 M KCl. The binding affinity of FND for the telomere DNA was ten times higher than that for calf thymus DNA under the conditions employed. Circular dichroism spectra suggested that the telomere DNA can form a tetraplex structure and FND can bind to it. Oligonucleotide extended by telomerase on the electrode could also be detected electrochemically by using FND, thereby suggesting the possibility that telomerase activity may be detected electrochemically.

  5. Integrated electrochemical transistor as a fast recoverable gas sensor.

    Science.gov (United States)

    Lange, Ulrich; Mirsky, Vladimir M

    2011-02-14

    A new design of conductometric chemical sensors based on conducting polymers as chemosensitive elements was suggested. The sensor includes six electrodes. Four inner electrodes coated by chemosensitive polymer are used for simultaneous two- and four-point resistance measurements thus providing information on the bulk polymer resistance and on the resistance of the polymer/electrode contacts. Two outer electrodes wired to inner electrodes by polymeric electrolyte are used for electrical control of redox state of the chemosensitive polymer. The outer electrodes are connected to potentiostat as reference and counter electrodes. It allows us to control redox state of the inner (working) electrodes. This new measurement configuration, resembling chemosensitive electrochemical transistors, provides an internal test of the sensor integrity and an electrically driven sensor regeneration. It was tested as a sensor for the detection of nitrogen dioxide. Polythiophene or polyaniline was used as receptors. Cyclic voltammograms of these polymers on the sensor surface measured in air atmosphere were very similar to that measured in aqueous electrolyte. A control of conductivity of these chemosensitive polymers by electrical potential applied vs. incorporated reference electrode was demonstrated. This effect was used for the regeneration of the chemosensitive material after exposure to nitrogen dioxide: in comparison to usual chemiresistors displaying an irreversible behavior in such test even in the time scale of hours, a completely reversible sensor regeneration within few minutes was observed.

  6. A mediator embedded micro-immunosensing unit for electrochemical detection on viruses within physiological saline media

    Science.gov (United States)

    Pires, Nuno M. M.; Dong, Tao; Yang, Zhaochu; Høivik, Nils; Zhao, Xinyan

    2011-11-01

    To provide a time- and cost-saving alternative to the conventional methods for virus detection in biological media, this work presents an electrochemical micro-immunosensor based on the nickel hexacyanoferrate (NiHCF) redox mediator film coating the interdigitated microelectrodes (IDMEs). By chelation binding with no additional cross-linker, the 6xHis-tagged antibodies were immobilized on a NiHCF film. Secondly, an immunoassay response was enhanced by employing microbeads coated with 6xHis antibody. The electrochemical properties and the stability of the NiHCF film modified IDMEs were evaluated by cyclic voltammetry. The bead-induced impedance variations at the electrode film/electrolyte interface were characterized by electrochemical impedance spectroscopy and verified using FEM simulation. Experiments of virus detection were conducted through targeting the antigens of the vital infectious salmon viruses, such as infectious salmon anaemia virus, infectious pancreatic necrosis virus and salmonid alphavirus subtype 3. The micro-immunosensor exhibited detection limits as low as 10 pg ml-1 and detection sensitivities as high as 57.5 kΩ µM-1 within a physiological saline solution. Tests for multiple antigen-antibody interactions showed good detection specificity, as confirmed by ELISA. By incorporating the microfluidic network, electrochemical impedance micro-immunosensing units can be realized in a fully integrated platform for multiplex virus detection in tissue samples.

  7. Electrochemical Detection of Horseradish Peroxidase at Zeptomole Level

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An electrochemical method for determination of horseradish peroxidase (HRP) was developed using a capillary catalytic system. HRP can be measured in several minutes with a detection limit of 4.8×10-12 mol/L or 47 zmol (S/N=3).

  8. Electrochemical immunosensors for Salmonella detection in food

    Science.gov (United States)

    Pathogen detection is a critical point for the identification and the prevention of problems related to food safety. Failures at detecting contaminations in food may cause outbreaks with drastic consequences to public health. In spite of the real need for obtaining analytical results in the shortest...

  9. Single-Nanowire Electrochemical Probe Detection for Internally Optimized Mechanism of Porous Graphene in Electrochemical Devices.

    Science.gov (United States)

    Hu, Ping; Yan, Mengyu; Wang, Xuanpeng; Han, Chunhua; He, Liang; Wei, Xiujuan; Niu, Chaojiang; Zhao, Kangning; Tian, Xiaocong; Wei, Qiulong; Li, Zijia; Mai, Liqiang

    2016-03-09

    Graphene has been widely used to enhance the performance of energy storage devices due to its high conductivity, large surface area, and excellent mechanical flexibility. However, it is still unclear how graphene influences the electrochemical performance and reaction mechanisms of electrode materials. The single-nanowire electrochemical probe is an effective tool to explore the intrinsic mechanisms of the electrochemical reactions in situ. Here, pure MnO2 nanowires, reduced graphene oxide/MnO2 wire-in-scroll nanowires, and porous graphene oxide/MnO2 wire-in-scroll nanowires are employed to investigate the capacitance, ion diffusion coefficient, and charge storage mechanisms in single-nanowire electrochemical devices. The porous graphene oxide/MnO2 wire-in-scroll nanowire delivers an areal capacitance of 104 nF/μm(2), which is 4.0 and 2.8 times as high as those of reduced graphene oxide/MnO2 wire-in-scroll nanowire and MnO2 nanowire, respectively, at a scan rate of 20 mV/s. It is demonstrated that the reduced graphene oxide wrapping around the MnO2 nanowire greatly increases the electronic conductivity of the active materials, but decreases the ion diffusion coefficient because of the shielding effect of graphene. By creating pores in the graphene, the ion diffusion coefficient is recovered without degradation of the electron transport rate, which significantly improves the capacitance. Such single-nanowire electrochemical probes, which can detect electrochemical processes and behavior in situ, can also be fabricated with other active materials for energy storage and other applications in related fields.

  10. Interface Design for CMOS-Integrated Electrochemical Impedance Spectroscopy (EIS Biosensors

    Directory of Open Access Journals (Sweden)

    Arjang Hassibi

    2012-10-01

    Full Text Available Electrochemical Impedance Spectroscopy (EIS is a powerful electrochemical technique to detect biomolecules. EIS has the potential of carrying out label-free and real-time detection, and in addition, can be easily implemented using electronic integrated circuits (ICs that are built through standard semiconductor fabrication processes. This paper focuses on the various design and optimization aspects of EIS ICs, particularly the bio-to-semiconductor interface design. We discuss, in detail, considerations such as the choice of the electrode surface in view of IC manufacturing, surface linkers, and development of optimal bio-molecular detection protocols. We also report experimental results, using both macro- and micro-electrodes to demonstrate the design trade-offs and ultimately validate our optimization procedures.

  11. Interface design for CMOS-integrated Electrochemical Impedance Spectroscopy (EIS) biosensors.

    Science.gov (United States)

    Manickam, Arun; Johnson, Christopher Andrew; Kavusi, Sam; Hassibi, Arjang

    2012-10-29

    Electrochemical Impedance Spectroscopy (EIS) is a powerful electrochemical technique to detect biomolecules. EIS has the potential of carrying out label-free and real-time detection, and in addition, can be easily implemented using electronic integrated circuits (ICs) that are built through standard semiconductor fabrication processes. This paper focuses on the various design and optimization aspects of EIS ICs, particularly the bio-to-semiconductor interface design. We discuss, in detail, considerations such as the choice of the electrode surface in view of IC manufacturing, surface linkers, and development of optimal bio-molecular detection protocols. We also report experimental results, using both macro- and micro-electrodes to demonstrate the design trade-offs and ultimately validate our optimization procedures.

  12. Interface Design for CMOS-Integrated Electrochemical Impedance Spectroscopy (EIS) Biosensors

    Science.gov (United States)

    Manickam, Arun; Johnson, Christopher Andrew; Kavusi, Sam; Hassibi, Arjang

    2012-01-01

    Electrochemical Impedance Spectroscopy (EIS) is a powerful electrochemical technique to detect biomolecules. EIS has the potential of carrying out label-free and real-time detection, and in addition, can be easily implemented using electronic integrated circuits (ICs) that are built through standard semiconductor fabrication processes. This paper focuses on the various design and optimization aspects of EIS ICs, particularly the bio-to-semiconductor interface design. We discuss, in detail, considerations such as the choice of the electrode surface in view of IC manufacturing, surface linkers, and development of optimal bio-molecular detection protocols. We also report experimental results, using both macro- and micro-electrodes to demonstrate the design trade-offs and ultimately validate our optimization procedures. PMID:23202170

  13. New analytical portable instrument for microchip electrophoresis with electrochemical detection.

    Science.gov (United States)

    Fernández-la-Villa, Ana; Pozo-Ayuso, Diego F; Castaño-Alvarez, Mario

    2010-08-01

    A new portable instrument that includes a high voltage power supply, a bipotentiostat, and a chip holder has been especially developed for using microchips electrophoresis with electrochemical detection. The main unit of the instrument has dimensions of 150 x 165 x 70 mm (wxdxh) and consists of a four-outputs high voltage power supply with a maximum voltage of +/-3 KV and an acquisition system with two channels for dual amperometric (DC or pulsed amperometric detection) detection. Electrochemical detection has been selected as signal transduction method because it is relatively easily implemented, since nonoptical elements are required. The system uses a lithium-ion polymer battery and it is controlled from a desktop or laptop PC with a graphical user interface based on LabVIEW connected by serial RS232 or Bluetooth. The last part of the system consists of a reusable chip holder for housing the microchips, which contain all the electrical connections and reservoirs for making the work with microchips easy. The performance of the new instrument has been evaluated and compared with other commercially available apparatus using single- and dual-channel pyrex microchips for the separation of the neurotransmitters dopamine, epinephrine, and 3,4-dihydroxy-L-phenyl-alanine. The reduction of the size of the instrument has not affected the good performance of the separation and detection using microchips electrophoresis with electrochemical detection. Moreover, the new portable instrument paves the way for in situ analysis making the use of microchips electrophoresis easier.

  14. Electrochemical Dopamine Detection: Comparing Gold and Carbon Fiber Microelectrodes using Background Subtracted Fast Scan Cyclic Voltammetry

    OpenAIRE

    Zachek, Matthew K.; Hermans, Andre; Wightman, R. Mark; McCarty, Gregory S.

    2008-01-01

    Electrochemical detection is becoming increasingly important for the detection of biological species. Most current biological research with electrochemical detection is done with carbon fiber electrodes due to their many beneficial properties. The ability to build electrochemical sensor from noble metals instead of carbon fibers may be beneficial in developing inexpensive multiplexed electrochemical detection schemes. To advance understanding and to test the feasibility of using noble metal e...

  15. Novel sensors for detection of azide and dopamine: Electrochemical studies

    Science.gov (United States)

    Dalmia, Avinash

    Electrochemical amperometric sensors have been used sucessfully for monitoring a wide variety of hazardous species. Electrochemical studies of azides have been conducted at carbon, platinum and gold to evaluate their sensing properties. The differences in electrochemical behavior of azides at carbon, platinum and gold are elucidated with rotating disc, ring-disc and DEMS (Differential Electrochemical mass spectroscopy). It has been observed that the electrooxidation of azides at carbon electrode results in formation of only nitrogen, whereas at platinum electrode, the electrooxidation of azides results in formation of both nitrogen and nitrogen oxides. Gold in presence of azide ions undergoes electrooxidation forming soluble gold azide complexes at lower potentials and nitrogen and nitrogen oxides at higher potentials. It was demonstrated that azides are much more electroactive than hydrazoic acid. This work has implication for design of electrochemical sensors to detect and monitor azide ions. Gold electrodes modified with self assembled monolayers offer possibilities of sensors with higher selectivity, stability, fast response time and higher sensitivity. In the second part of this thesis, gold electrodes modified with SAM (self assembled monolayer) with acidic end group for selective detection of catecholamines were evaluated. SAM modified substrates have been characterized using different techniques, i.e., electrochemical desorption, capacitance measurements, angle resolved XPS measurements, potentiometric measurements and cyclic voltammetric measurements. The electrochemical desorption measurements show that the coverage of SAM molecules corresponds to a monolayer. Capacitance measurements demonstrate that the capacitance depends on the length, end group and defects present in monolayers. Angle resolved XPS has been demonstrated as a powerful tool for studying the anisotropic atomic distribution in monolayer film. The cyclic voltammetric measurements show that

  16. Nucleosides and ODN electrochemical detection onto boron doped diamond electrodes.

    Science.gov (United States)

    Fortin, Elodie; Chane-Tune, Jérôme; Mailley, Pascal; Szunerits, Sabine; Marcus, Bernadette; Petit, Jean-Pierre; Mermoux, Michel; Vieil, Eric

    2004-06-01

    Boron doped diamond (BDD) is a promising material for electroanalytical chemistry due mainly to its chemical stability, its high electrical conductivity and to the large amplitude of its electroactive window in aqueous media. The latter feature allowed us to study the direct oxidation of the two electroactive nucleosides, guanosine and adenosine. The BDD electrode was first activated by applying high oxidizing potentials, allowing to increase anodically its working potential window through the oxidation of CH surface groups into hydroxyl and carbonyl terminations. Guanosine (1.2 V vs. Ag/AgCl) and adenosine (1.5 V vs. Ag/AgCl) could then be detected electrochemically with an acceptable signal to noise ratio. The electrochemical signature of each oxidizable base was assessed using differential pulse voltammetry (DPV), in solutions containing one or both nucleosides. These experiments pointed out the existence of adsorption phenomena of the oxidized products onto the diamond surface. Scanning electrochemical microscopy (SECM) was used to investigate these adsorption effects at the microscopic scale. The usefulness of BDD electrodes for the direct electrochemical detection of synthetic oligonucleotides is also evidenced.

  17. Beyond graphene: Electrochemical sensors and biosensors for biomarkers detection.

    Science.gov (United States)

    Bollella, Paolo; Fusco, Giovanni; Tortolini, Cristina; Sanzò, Gabriella; Favero, Gabriele; Gorton, Lo; Antiochia, Riccarda

    2017-03-15

    Graphene's success has stimulated great interest and research in the synthesis and characterization of graphene-like 2D materials, single and few-atom-thick layers of van der Waals materials, which show fascinating and technologically useful properties. This review presents an overview of recent electrochemical sensors and biosensors based on graphene and on graphene-like 2D materials for biomarkers detection. Initially, we will outline different electrochemical sensors and biosensors based on chemically derived graphene, including graphene oxide and reduced graphene oxide, properly functionalized for improved performances and we will discuss the various strategies to prepare graphene modified electrodes. Successively, we present electrochemical sensors and biosensors based on graphene-like 2D materials, such as boron nitride (BN), graphite-carbon nitride (g-C3N4), transition metal dichalcogenides (TMDs), transition metal oxides and graphane, outlining how the new modified 2D nanomaterials will improve the electrochemical performances. Finally, we will compare the results obtained with different sensors and biosensors for the detection of important biomarkers such as glucose, hydrogen peroxide and cancer biomarkers and highlight the advantages and disadvantages of the use of graphene and graphene-like 2D materials in different sensing platforms. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. A nanocoaxial-based electrochemical sensor for the detection of cholera toxin.

    Science.gov (United States)

    Archibald, Michelle M; Rizal, Binod; Connolly, Timothy; Burns, Michael J; Naughton, Michael J; Chiles, Thomas C

    2015-12-15

    Sensitive, real-time detection of biomarkers is of critical importance for rapid and accurate diagnosis of disease for point of care (POC) technologies. Current methods do not allow for POC applications due to several limitations, including sophisticated instrumentation, high reagent consumption, limited multiplexing capability, and cost. Here, we report a nanocoaxial-based electrochemical sensor for the detection of bacterial toxins using an electrochemical enzyme-linked immunosorbent assay (ELISA) and differential pulse voltammetry (DPV) or square wave voltametry (SWV). The device architecture is composed of vertically-oriented, nanoscale coaxial electrodes in array format (~10(6) coaxes per square millimeter). The coax cores and outer shields serve as integrated working and counter electrodes, respectively, exhibiting a nanoscale separation gap corresponding to ~100 nm. Proof-of-concept was demonstrated for the detection of cholera toxin (CT). The linear dynamic range of detection was 10 ng/ml-1 µg/ml, and the limit of detection (LOD) was found to be 2 ng/ml. This level of sensitivity is comparable to the standard optical ELISA used widely in clinical applications, which exhibited a linear dynamic range of 10 ng/ml-1 µg/ml and a LOD of 1 ng/ml. In addition to matching the detection profile of the standard ELISA, the nanocoaxial array provides a simple electrochemical readout and a miniaturized platform with multiplexing capabilities for the simultaneous detection of multiple biomarkers, giving the nanocoax a desirable advantage over the standard method towards POC applications.

  19. Electrochemical impedance spectroscopy biosensor for detection of active botulinum neurotoxin

    Directory of Open Access Journals (Sweden)

    Jennifer Halliwell

    2014-12-01

    Full Text Available The standard method for the detection of botulinum neurotoxin is currently the mouse bioassay which is considered to be the most reliable method for the detection of the active form of this toxin. Despite this it is a time-consuming and expensive assay to run and as such many alternative assays have recently been proposed. Herein we report the development of two electrochemical assays for the detection of active botulinum neurotoxin in a pharmaceutical sample. Gold electrodes were modified with self-assembled monolayers of the SNARE protein SNAP-25 which is selectively cleaved by active botulinum neurotoxin A. Cyclic voltammetry and electrochemical impedance spectroscopy were performed on the modified working electrodes to observe changes to the layer on addition of the toxin. Both methods were able to distinguish the difference between the presence of the active toxin and a placebo containing the excipients of the pharmaceutical product. The electrochemical impedance spectroscopy assay also allowed for detection of the active toxin at concentrations as low as 25 fg/ml, with results being obtained in under an hour outperforming the mouse bioassay.

  20. Integrated Electrochemical Analysis System with Microfluidic and Sensing Functions

    Directory of Open Access Journals (Sweden)

    Hiroaki Suzuki

    2008-02-01

    Full Text Available An integrated device that carries out the timely transport of solutions andconducts electroanalysis was constructed. The transport of solutions was based oncapillary action in overall hydrophilic flow channels and control by valves that operateon the basis of electrowetting. Electrochemical sensors including glucose, lactate,glutamic oxaloacetic transaminase (GOT, glutamic pyruvic transaminase (GPT, pH,ammonia, urea, and creatinine were integrated. An air gap structure was used for theammonia, urea, and creatinine sensors to realize a rapid response. To enhance thetransport of ammonia that existed or was produced by the enzymatic reactions, the pHof the solution was elevated by mixing it with a NaOH solution using a valve based onelectrowetting. The sensors for GOT and GPT used a freeze-dried substrate matrix torealize rapid mixing. The sample solution was transported to required sensing sites atdesired times. The integrated sensors showed distinct responses when a sample solutionreached the respective sensing sites. Linear relationships were observed between theoutput signals and the concentration or the logarithm of the concentration of theanalytes. An interferent, L-ascorbic acid, could be eliminated electrochemically in thesample injection port.

  1. 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).

  2. Hybrid carbon nanomaterials for electrochemical detection of biomolecules

    Science.gov (United States)

    Laurila, Tomi

    2015-09-01

    Electrochemical detection of different biomolecules in vivo is a promising path towards in situ monitoring of human body and its functions. However, there are several major obstacles, such as sensitivity, selectivity and biocompatiblity, which must be tackled in order to achieve reliably and safely operating sensor devices. Here we show that by utilizing hybrid carbon materials as electrodes to detect two types of neurotransmitters, dopamine and glutamate, several advantages over commonly used electrode materials can be achieved. In particular, we will demonstrate here that it is possible to combine the properties of different carbon allotropes to obtain hybrid materials with greatly improved electrochemical performance. Three following examples of the approach are given: (i) diamond-like carbon (DLC) thin film electrodes with different layer thicknesses, (ii) multi-walled carbon nanotubes grown directly on top of DLC and (iii) carbon nanofibres synthesized on top of DLC thin films. Detailed structural and electrochemical characterization is carried out to rationalize the reasons behind the observed behvior. In addition, results from the atomistic simulations are utilized to obtain more information about the properties of the amorphous carbon thin films.

  3. Electrochemical Sensor for Explosives Precursors’ Detection in Water

    Directory of Open Access Journals (Sweden)

    Cloé Desmet

    2017-03-01

    Full Text Available Although all countries are intensifying their efforts against terrorism and increasing their mutual cooperation, terrorist bombing is still one of the greatest threats to society. The discovery of hidden bomb factories is of primary importance in the prevention of terrorism activities. Criminals preparing improvised explosives (IE use chemical substances called precursors. These compounds are released in the air and in the waste water during IE production. Tracking sources of precursors by analyzing air or wastewater can then be an important clue for bomb factories’ localization. We are reporting here a new multiplex electrochemical sensor dedicated to the on-site simultaneous detection of three explosive precursors, potentially used for improvised explosive device preparation (hereafter referenced as B01, B08, and B15, for security disclosure reasons and to avoid being detrimental to the security of the counter-explosive EU action. The electrochemical sensors were designed to be disposable and to combine ease of use and portability in a screen-printed eight-electrochemical cell array format. The working electrodes were modified with different electrodeposited metals: gold, palladium, and platinum. These different coatings giving selectivity to the multi-sensor through a “fingerprint”-like signal subsequently analyzed using partial least squares-discriminant analysis (PLS-DA. Results are given regarding the detection of the three compounds in a real environment and in the presence of potentially interfering species.

  4. Apolipoprotein B100 analysis in microchip with electrochemical detection

    Institute of Scientific and Technical Information of China (English)

    Cheng Cheng Liu; Yun Liu; Hui Xiang Wang; Yan Bo Qi; Peng Yuan Yang; Bao Hong Liu

    2011-01-01

    Apolipoprotein B100 (apoB-100) is a major protein of the cholesterol-rich low-density lipoprotein (LDL) and reflects a better assessment of total atherogenic burden to the vascular system than LDL. In this work, a simple and sensitive method has been developed to determine picoliter apoB-100s using the PMMA microfluidic chip coupled with electrochemical detection system. This method performs very well with a detectable linear range of 1-800 pg/mL and a detection limit of 1 pg/mL. A real serum sample has further been detected by this microchip-based biosensor. The results show that this kind of method is practicable and has the potential application in clinical analysis and diagnosis.

  5. Development of an aptasensor for electrochemical detection of exosomes.

    Science.gov (United States)

    Zhou, Qing; Rahimian, Ali; Son, Kyungjin; Shin, Dong-Sik; Patel, Tushar; Revzin, Alexander

    2016-03-15

    Exosomes are small (50-100 nm in diameter) vesicles secreted from various mammalian cells. Exosomes have been correlated with tumor antigens and anti-tumor immune responses and may represent cancer biomarkers. Herein, we report on the development of an aptamer-based electrochemical biosensor for quantitative detection of exosomes. Aptamers specific to exosome transmembrane protein CD63 were immobilized onto gold electrode surfaces and incorporated into a microfluidic system. Probing strands pre-labeled with redox moieties were hybridized onto aptamer molecules anchored on the electrode surface. In the presence of exosomes these beacons released probing strands with redox reporters causing electrochemical signal to decrease. These biosensors could be used to detect as few as 1×10(6) particles/mL of exosomes, which represents 100-fold decrease in the limit of detection compared to commercial immunoassays relying on anti-CD63 antibodies. Given the importance of exosome-mediated signal transmission among cells, our study may represent an important step towards development of a simple biosensor that detects exosomes without washing or labeling steps in complex media.

  6. Botulinum Neurotoxin Serotypes Detected by Electrochemical Impedance Spectroscopy

    Science.gov (United States)

    Savage, Alison C.; Buckley, Nicholas; Halliwell, Jennifer; Gwenin, Christopher

    2015-01-01

    Botulinum neurotoxin is one of the deadliest biological toxins known to mankind and is able to cause the debilitating disease botulism. The rapid detection of the different serotypes of botulinum neurotoxin is essential for both diagnosis of botulism and identifying the presence of toxin in potential cases of terrorism and food contamination. The modes of action of botulinum neurotoxins are well-established in literature and differ for each serotype. The toxins are known to specifically cleave portions of the SNARE proteins SNAP-25 or VAMP; an interaction that can be monitored by electrochemical impedance spectroscopy. This study presents a SNAP-25 and a VAMP biosensors for detecting the activity of five botulinum neurotoxin serotypes (A–E) using electrochemical impedance spectroscopy. The biosensors are able to detect concentrations of toxins as low as 25 fg/mL, in a short time-frame compared with the current standard methods of detection. Both biosensors show greater specificity for their compatible serotypes compared with incompatible serotypes and denatured toxins. PMID:25954998

  7. Botulinum Neurotoxin Serotypes Detected by Electrochemical Impedance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Alison C. Savage

    2015-05-01

    Full Text Available Botulinum neurotoxin is one of the deadliest biological toxins known to mankind and is able to cause the debilitating disease botulism. The rapid detection of the different serotypes of botulinum neurotoxin is essential for both diagnosis of botulism and identifying the presence of toxin in potential cases of terrorism and food contamination. The modes of action of botulinum neurotoxins are well-established in literature and differ for each serotype. The toxins are known to specifically cleave portions of the SNARE proteins SNAP-25 or VAMP; an interaction that can be monitored by electrochemical impedance spectroscopy. This study presents a SNAP-25 and a VAMP biosensors for detecting the activity of five botulinum neurotoxin serotypes (A–E using electrochemical impedance spectroscopy. The biosensors are able to detect concentrations of toxins as low as 25 fg/mL, in a short time-frame compared with the current standard methods of detection. Both biosensors show greater specificity for their compatible serotypes compared with incompatible serotypes and denatured toxins.

  8. An electrochemical immunosensor for quantitative detection of ficolin-3

    Science.gov (United States)

    San, Lili; Zeng, Dongdong; Song, Shiping; Zuo, Xiaolei; Zhang, Huan; Wang, Chenguang; Wu, Jiarui; Mi, Xianqiang

    2016-06-01

    Diabetes mellitus (DM) is one of the most common metabolic disorders in the world, of which more than 90% is type-2 diabetes mellitus (T2DM). There is a rather urgent need for reliable, sensitive and quick detection techniques in clinical application of T2DM. Ficolin-3 is a potential biomarker of T2DM, because serum ficolin-3 levels are associated with insulin resistance and predict the incidence of T2DM. Herein, a sandwich-type electrochemical immunosensor was developed for the detection of ficolin-3 in human serum. Cyclic voltammetry and the amperometric current versus time were used to characterize the performance of the immunosensor. Under optimal conditions, the detection limitation of ficolin-3 was 100 ng ml-1 and the linear dynamic range was between 2 and 50 μg ml-1. The method has ideal accuracy, excellent stability and selectivity and has wide application prospects in clinical research.

  9. Rapid in situ detection of ultratrace 2,4-dinitrotoluene solids by a sandwiched paper-like electrochemical sensor.

    Science.gov (United States)

    Wang, Juan; Jin, Wei; Zhang, Xing; Hu, Chengguo; Luo, Qingying; Lin, Yi; Hu, Shengshui

    2014-08-19

    This work reported the rapid in situ detection of ultratrace 2,4-dinitrotoluene (DNT) solids on various substrates by a sandwiched paper-like electrochemical sensor. The sensor, prepared by a simple electroless deposition method without using special instruments, possessed a unique thin-film structure of an insulated polyvinylidene fluoride (PVDF) membrane in between two gold (Au) conducting layers. The resulting gold-PVDF sandwich (GPVDFS) array exhibited excellent flexibility, porosity and electrochemical performance as a highly integrated dual-electrode sensor platform. The infiltration of nonvolatile ionic liquid (IL) electrolytes containing ferrocene (Fc) into the GPVDFS array produced a paper-like electrochemical sensor, which can directly detect ultratrace DNT solids on various substrate surfaces (e.g., plant leaves, gloves and metal knives) with detection limit as low as 0.33 ng/mm(2). The critical role of Fc in the detection of DNT at this dual-electrode sensor was explored. The compensating electrochemical oxidation of Fc at the counter/reference electrode was found to be essential to the reduction of DNT at the working electrode when IL electrolytes were employed. The present work thus demonstrated the promising applications of paper-based porous electrode arrays in developing IL-based electrochemical sensors for the in situ detection of analyte solids in complicated environments.

  10. Indirect electrochemical detection of type-B trichothecene mycotoxins.

    Science.gov (United States)

    Hsueh, C C; Liu, Y; Freund, M S

    1999-09-15

    Trichothecene mycotoxins in animal feed and human food can cause fatalities in livestock and disease in humans. In addition, these toxins are suspected chemical warfare agents. Therefore, development of a simple and sensitive method for the screening of trichothecenes is important to prevent economic loss and health hazards. A simple and inexpensive method for the detection of type-B trichothecene mycotoxins has been developed in our laboratory. By hydrolyzing the toxin under basic conditions at 80 degrees C for 1 h it is possible to detect the toxin with simple electrochemical techniques. Deoxynivalenol (DON), commonly known as vomitoxin, was used as a representative compound for type-B trichothecenes in this detection scheme. The detection limit for DON using our procedures was determined to be 9.1 microM in solution, corresponding to 0.24 ppm in a 25-g grain sample if the final extraction volume is 2.2 mL. The linear dynamic detection range was determined to be from 0.32 ppm to greater than 32 ppm. In addition to standard solutions, this method was used on rice samples spiked with DON. It was demonstrated that there is no electrochemical interference from rice extract and that 1 ppm of DON in rice samples can be quantified. This method may be ideal for toxin screening in animal feeds or in runoff from sites that produce the compounds as chemical warfare agents. Since the active moiety in DON is common to virtually all type-B trichothecenes, our approach may be ideal for type-specific screening.

  11. An Electrochemical DNA Biosensor for the Detection of Salmonella Using Polymeric Films and Electrochemical Labels

    Science.gov (United States)

    Diaz Serrano, Madeline

    Waterborne and foodborne diseases are one of the principal public health problems worldwide. Microorganisms are the major agents of foodborne illness: pathogens such as Salmonella, Campylobacter jejuni and Escherichia coli, and parasites such as cryptosporidium. The most popular methods to detect Salmonella are based on culture and colony counting methods, ELISA, Gel electrophoresis and the polymerase chain reaction. Conventional detection methods are laborious and time-consuming, allowing for portions of the food to be distributed, marketed, sold and eaten before the analysis is done and the problem even detected. By these reasons, the rapid, easy and portable detection of foodborne organisms will facilitate the disease treatment. Our particular interest is to develop a nucleic acid biosensor (NAB) for the detection of pathogenic microorganisms in food and water samples. In this research, we report on the development of a NAB prototype using a polymer modified electrode surface together with sequences of different lengths for the OmpC gene from Salmonella as probes and Ferrocene-labeled target (Fc-ssDNA), Ferrocene-labeled tri(ethylene glycol) (Fc-PEG) and Ruthenium-Ferrocene (Ru-Fe) bimetallic complex as an electrochemical labels. We have optimized several PS films and anchored nucleic acid sequences with different lengths at gold and carbon surfaces. Non contact mode AFM and XPS were used to monitor each step of the NAB preparation, from polymer modification to oligos hybridization (conventional design). The hybridization reaction was followed electrochemically using a Fc-ssDNA and Fc-PEG in solution taking advantage of the morphological changes generated upon hybridization. We observed a small current at the potential for the Fe oxidation without signal amplification at +296 mV vs. Ag/AgCl for the Fc-ssDNA strategy and a small current at +524 mV for the Fc-PEG strategy. The immobilization, hybridization and signal amplification of Biotin- OmpC Salmonella genes

  12. Single Molecule Electrochemical Detection in Aqueous Solutions and Ionic Liquids.

    Science.gov (United States)

    Byers, Joshua C; Paulose Nadappuram, Binoy; Perry, David; McKelvey, Kim; Colburn, Alex W; Unwin, Patrick R

    2015-10-20

    Single molecule electrochemical detection (SMED) is an extremely challenging aspect of electroanalytical chemistry, requiring unconventional electrochemical cells and measurements. Here, SMED is reported using a "quad-probe" (four-channel probe) pipet cell, fabricated by depositing carbon pyrolytically into two diagonally opposite barrels of a laser-pulled quartz quadruple-barreled pipet and filling the open channels with electrolyte solution, and quasi-reference counter electrodes. A meniscus forms at the end of the probe covering the two working electrodes and is brought into contact with a substrate working electrode surface. In this way, a nanogap cell is produced whereby the two carbon electrodes in the pipet can be used to promote redox cycling of an individual molecule with the substrate. Anticorrelated currents generated at the substrate and tip electrodes, at particular distances (typically tens of nanometers), are consistent with the detection of single molecules. The low background noise realized in this droplet format opens up new opportunities in single molecule electrochemistry, including the use of ionic liquids, as well as aqueous solution, and the quantitative assessment and analysis of factors influencing redox cycling currents, due to a precisely known gap size.

  13. Multilevel electrochemical signal detections of metalloprotein heterolayers for bioelectronic device

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Yong-Ho; Yoo, Si-Youl; Lee, Taek [Department of Chemical and Biomolecular Engineering, Sogang University, 35 Baekbeom-ro(Sinsu-dong), Mapo-gu, Seoul 121-742 (Korea, Republic of); Lee, Hun Joo [Interdisciplinary Program of Integrated Biotechnology, Sogang University, 35 Baekbeomro(Sinsu-dong), Mapo-gu, Seoul 121-742 (Korea, Republic of); Min, Junhong [School of Integrative Engineering, Chung-Ang University, Heukseok-dong, Dongjak-gu, Seoul 156-756 (Korea, Republic of); Choi, Jeong-Woo, E-mail: jwchoi@sogang.ac.kr [Department of Chemical and Biomolecular Engineering, Sogang University, 35 Baekbeom-ro(Sinsu-dong), Mapo-gu, Seoul 121-742 (Korea, Republic of); Interdisciplinary Program of Integrated Biotechnology, Sogang University, 35 Baekbeomro(Sinsu-dong), Mapo-gu, Seoul 121-742 (Korea, Republic of)

    2014-01-31

    In the present study, we investigated the simultaneous detection of multilevel electrochemical signals from various metalloprotein heterolayers for the bioelectronic devices. A layer-by-layer assembly method based on simple electrostatic interaction was introduced to form protein bilayers. The gold substrate was modified with poly (ethylene glycol) thiol acid as the precursor, which introduced negative charges to the surface. Based on the isoelectric point, net-charge controlled metalloproteins by pH adjustment were sequentially immobilized on this negatively charged substrate. The degree of protein immobilization on the gold substrate was confirmed by surface plasmon resonance spectroscopy, and the surface topology changes due to the protein immobilization were confirmed by atomic force microscopy. Redox signals in the protein layers were measured by cyclic voltammetry. As a result, various redox signals generated from different metalloproteins on a single electrode were monitored. This proposed method for the detection of multi-level electrochemical signals can be directly applied to bioelectronic devices that store multi-information in a single electrode. - Highlights: • We fabricated heterolayers composed of various metalloproteins. • Metalloproteins were immobilized by layer-by-layer assembly. • The degree of immobilization was controlled by the net charge of metalloproteins. • Various redox signals generated from heterolayers were well monitored.

  14. Electrochemical immunochip sensor for aflatoxin M1 detection.

    Science.gov (United States)

    Parker, Charlie O; Lanyon, Yvonne H; Manning, Mary; Arrigan, Damien W M; Tothill, Ibtisam E

    2009-07-01

    An investigation into the fabrication, electrochemical characterization, and development of a microelectrode array (MEA) immunosensor for aflatoxin M(1) is presented in this paper. Gold MEAs (consisting of 35 microsquare electrodes with 20 microm x 20 microm dimensions and edge-to-edge spacing of 200 microm) together with on-chip reference and counter electrodes were fabricated using standard photolithographic methods. The MEAs were then characterized by cyclic voltammetry, and the behavior of the on-chip electrodes were evaluated. The microarray sensors were assessed for their applicability to the development of an immunosensor for the analysis of aflatoxin M(1) directly in milk samples. Following the sensor surface silanization, antibodies were immobilized by cross-linking with 1,4-phenylene diisothiocyanate (PDITC). Surface characterization was conducted by electrochemistry, fluorescence microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). A competitive enzyme linked immunosorbent assay (ELISA) assay format was developed on the microarray electrode surface using the 3,3,5',5'-tetramethylbenzidine dihyrochloride (TMB)/H(2)O(2) electrochemical detection scheme with horseradish peroxidase (HRP) as the enzyme label. The performance of the assay and the microarray sensor were characterized in pure buffer conditions before applying to the milk samples. With the use of this approach, the detection limit for aflatoxin M(1) in milk was estimated to be 8 ng L(-1), with a dynamic detection range of 10-100 ng L(-1), which meets present legislative limits of 50 ng L(-1). The milk interference with the sensor surface was also found to be minimal. These devices show high potential for development of a range of new applications which have previously only been detected using elaborate instrumentation.

  15. A bacteriophage endolysin-based electrochemical impedance biosensor for the rapid detection of Listeria cells.

    Science.gov (United States)

    Tolba, Mona; Ahmed, Minhaz Uddin; Tlili, Chaker; Eichenseher, Fritz; Loessner, Martin J; Zourob, Mohammed

    2012-12-21

    The objective of this study was to develop a biosensor using the cell wall binding domain (CBD) of bacteriophage-encoded peptidoglycan hydrolases (endolysin) immobilized on a gold screen printed electrode (SPE) and subsequent electrochemical impedance spectroscopy (EIS) for a rapid and specific detection of Listeria cells. The endolysin was amine-coupled to SPEs using EDC/NHS chemistry. The CBD-based electrode was used to capture and detect the Listeria innocua serovar 6b from pure culture and 2% artificially contaminated milk. In our study, the endolysin functionalized SPEs have been characterized using X-ray photoelectron spectroscopy (XPS). The integration of endolysin-based recognition for specific bacteria and EIS can be used for direct and rapid detection of Listeria cells with high specificity against non-Listeria cells with a limit of detection of 1.1 × 10(4) and 10(5) CFU mL(-1) in pure culture and 2% milk, respectively.

  16. Detection of microbiologically influenced corrosion by electrochemical noise transients

    NARCIS (Netherlands)

    Homborg, A.M.; Morales, C.F. Leon; Tinga, Tiedo; de Wit, J.H.W.; Mol, J.M.C.

    2014-01-01

    This work investigates the electrochemical processes involved in pitting corrosion induced by microbiologically influenced corrosion by using time-resolved instantaneous frequency information of electrochemical current noise (ECN) transients obtained from Hilbert spectra. In addition to the

  17. Electrochemical techniques for subsecond neurotransmitter detection in live rodents.

    Science.gov (United States)

    Hascup, Kevin N; Hascup, Erin R

    2014-08-01

    Alterations in neurotransmission have been implicated in numerous neurodegenerative and neuropsychiatric disorders, including Alzheimer disease, Parkinson disease, epilepsy, and schizophrenia. Unfortunately, few techniques support the measurement of real-time changes in neurotransmitter levels over multiple days, as is essential for ethologic and pharmacodynamic testing. Microdialysis is commonly used for these research paradigms, but its poor temporal and spatial resolution make this technique inadequate for measuring the rapid dynamics (milliseconds to seconds) of fast signaling neurotransmitters, such as glutamate and acetylcholine. Enzymatic microelectrode arrays (biosensors) coupled with electrochemical recording techniques have demonstrated fast temporal resolution (less than 1 s), excellent spatial resolution (micron-scale), low detection limits (≤200 nM), and minimal damage (50 to 100 μm) to surrounding brain tissue. Here we discuss the benefits, methods, and animal welfare considerations of using platinum microelectrodes on a ceramic substrate for enzyme-based electrochemical recording techniques for real-time in vivo neurotransmitter recordings in both anesthetized and awake, freely moving rodents.

  18. Electrochemical diamond sensors for TNT detection in water

    Energy Technology Data Exchange (ETDEWEB)

    Sanoit, J. de [CEA-LIST-DETECS, Laboratoire Capteur Diamant, CEA-Saclay, Gif-sur Yvette, F-91191 (France)], E-mail: jacques.desanoit@cea.fr; Vanhove, Emilie [CEA-LIST-DETECS, Laboratoire Capteur Diamant, CEA-Saclay, Gif-sur Yvette, F-91191 (France); Mailley, Pascal [INAC, SPrAM, CREAB (CEA-Grenoble), F-38021 (France); Bergonzo, Philippe [CEA-LIST-DETECS, Laboratoire Capteur Diamant, CEA-Saclay, Gif-sur Yvette, F-91191 (France)

    2009-10-01

    An electrochemically stabilized boron doped diamond electrode prepared by chemical vapour deposition (CVD) is used for electrochemical TNT sensing in aqueous solutions. Square wave voltammograms (SWVs) exhibit three highly resolved peaks at -0.47, -0.62 and -0.76 V vs. Ag-AgCl reference electrode, respectively. The current vs. TNT concentration plot shows a linear relationship with a same slope for the two first TNT peaks at {mu}g L{sup -1} and mg L{sup -1} concentration ranges. Detection and quantification limits of 10 and 25 {mu}g L{sup -1}, respectively, were obtained without any preconcentration step. Relative standard deviation (RSD) of less than 1% measured over 10 runs has been found for the -0.47 V peak current showing the very high stability of the electrode without any significant fouling effect. An interference study with nitro aromatic compounds of the same family (nitro toluene and dinitrotoluene) has shown that the -0.47 V reduction peak enables TNT discrimination. Measurement of TNT in a natural medium (sea water without any purification step except filtering) has been also investigated.

  19. Electrochemical genosensor for the rapid detection of GMO using loop-mediated isothermal amplification.

    Science.gov (United States)

    Ahmed, Minhaz Uddin; Saito, Masato; Hossain, M Mosharraf; Rao, S Ramachandara; Furui, Satoshi; Hino, Akihiro; Takamura, Yuzuru; Takagi, Masahiro; Tamiya, Eiichi

    2009-05-01

    In this study, we are reporting for the first time an efficient, accurate and inexpensive rapid detection system which employs the integration of isothermal amplification and subsequent analysis of unpurified amplicons by an electrochemical system. In our experiments, loop-mediated isothermal amplification (LAMP) with its higher efficiency than PCR was performed at a constant temperature (65 degrees C). Amplification products were combined with a redox active molecule Hoechst 33258 [H33258, 2'-(4-hydroxyphenyl)-5-(4-methyl-1-piperazinyl)-2,5'-bi(1H-benzimidazole)] and analyzed by a DNA stick (DS) which is integrated with a disposable electrochemical printed (DEP) chip using linear sweep voltammetry (LSV). The DNA minor groove binding of the H33258 molecule causes a significant drop in the peak current intensity of the H33258 oxidation. The phenomenon of DNA binding induced by H33258, in addition to changes in the anodic current peak, was used to detect maize CBH 351 variety (StarLink). Since laborious probe immobilization was not required, and amplification and detection were performed on a single device, our biosensor eliminates potential cross-contamination. We believe that this type of sensor will have an unprecedented impact for environmental protection.

  20. Integration of β-cyclodextrin into graphene quantum dot nano-structure and its application towards detection of Vitamin C at physiological pH: A new electrochemical approach

    Energy Technology Data Exchange (ETDEWEB)

    Shadjou, Nasrin, E-mail: Nasrin.Shadjou@gmail.com [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); Hasanzadeh, Mohammad, E-mail: mhmmd_hasanzadeh@yahoo.com [Drug Applied Research Center, Tabriz University of Medical Sciences, Tabriz 51664 (Iran, Islamic Republic of); Pharmaceutical Analysis Research Center and Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz 51664 (Iran, Islamic Republic of); Talebi, Faeze; Marjani, Ahmad Poursattar [Department of Chemistry, Faculty of Science, Urmia University, Urmia 57154 (Iran, Islamic Republic of)

    2016-10-01

    For the first time, β-Cyclodextrin (β-CD) attachment to graphene quantum dot (GQD) structure was performed using simultaneous electrodeposition of GQD and β-CD on the surface of glassy carbon electrode (GCE). Cyclic voltammetry at potential range − 1.0 to 1.0 V from mixture of GQD and β-CD produced a well-defined β-CD-GQD deposited on the surface of glassy carbon electrode. β-CD-GQD modified GCE was used as a new electrocatalytical nanocomposite towards electrooxidation of Vitamin C (as sample analyte). The synergistic effects and the catalytic activity of the β-CD-GQD modified GCE were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) chronoamperometry (CA) and square wave voltammetry (SWV). The process of oxidation involved and its kinetics were established by using cyclic voltammetry, chronoamperometry techniques. It has been found that in the course of an anodic potential sweep the electro-oxidation of Vitamin C is catalyzed by synergetic effect of β-CD and GQD through a mediated electron transfer mechanism. Therefore, β-CD-GQDs promote the rate of oxidation by increasing the peak current. The cyclic voltammetric results indicate that β-CD-GQDs-GCE can remarkably enhance electroactivity towards the oxidation of Vitamin C in buffer solution. We have illustrated that the as-obtained β-CD-GQDs-GCE exhibited a much higher electrocatalytical behavior than GQDs for the electrooxidation and detection of Vitamin C which was about two fold higher than for GQDs. The electrochemical behavior was further exploited as detection scheme for the Vitamin C electrooxidation by square wave voltammetry. - Graphical abstract: Stable electroactive modified electrode using electrodeposition of GQD in the presence β-CD was prepared by cyclic voltammetry. It was found that the β-CD-GQD-GCE exhibit good catalytic activity for the oxidation of Vitamin C at a reduced overpotential and it has a significant high response for Vitamin C oxidation

  1. Bismuth nanoparticles integration into heavy metal electrochemical stripping sensor.

    Science.gov (United States)

    Cadevall, Miquel; Ros, Josep; Merkoçi, Arben

    2015-08-01

    Between their many applications bismuth nanoparticles (BiNPs) are showing interest as pre-concentrators in heavy metals detection while being applied as working electrode modifiers used in electrochemical stripping analysis. From the different reported methods to synthesize BiNPs we are focused on the typical polyol method, largely used in these types of metallic and semi-metallic nanoparticles. This study presents the strategy for an easy control of the shape and size of BiNPs including nanocubes, nanosferes and triangular nanostructures. To improve the BiNP size and shape, different reducing agents (ethylene glycol or sodium hypophosphite) and stabilizers (polyvinyl pyrrolidone, PVP, in different amounts) have been studied. The efficiency of BiNPs for heavy metals analysis in terms of detection sensitivity while being used as modifiers of screen-printed carbon electrodes including the applicability of the developed device in real sea water samples is shown. A parallel study between the obtained nanoparticles and their performance in heavy metal sensing has been described in this communication.

  2. The electrochemical detection of droplets in microfluidic devices.

    Science.gov (United States)

    Liu, Shujuan; Gu, Yunfeng; Le Roux, Rudolph B; Matthews, Sinéad M; Bratton, Daniel; Yunus, Kamran; Fisher, Adrian C; Huck, Wilhelm T S

    2008-11-01

    This paper presents a new electrochemical method for the detection and characterisation of aqueous droplets in an organic carrier fluid (1,2-dichloroethane) formed in flow-focusing microfluidic devices. The devices consist of a conventional flow-focusing channel 250 microm wide and 250 microm deep cast out of poly(dimethylsiloxane) (PDMS) which is sealed onto a glass substrate containing a set of microelectrodes 100 microm long. Chronoamperometric analysis of a suitable electrolyte contained in the organic phase is presented for characterising the droplet frequency and size. This chronoamperometric method is then extended to a dual working electrode approach in order to determine the velocity of the droplet. Good agreement between experimental measurements and theory was observed.

  3. A Fully Integrated and Miniaturized Heavy-metal-detection Sensor Based on Micro-patterned Reduced Graphene Oxide

    OpenAIRE

    2016-01-01

    For this paper, a fully integrated and highly miniaturized electrochemical sensor was designed and fabricated on a silicon substrate. A solvothermal-assisted reduced graphene oxide named “TRGO” was then successfully micro-patterned using a lithography technique, followed by the electrodeposition of bismuth (Bi) on the surface of the micro-patterned TRGO for the electrochemical detection of heavy metal ions. The fully integrated electrochemical micro-sensor was then measured and evaluated for ...

  4. Electrochemical detection of single cancer and healthy cell collisions on a microelectrode.

    Science.gov (United States)

    Dick, Jeffrey E

    2016-09-18

    The electrochemical detection of single cancer cells and healthy cells is reported. Detection was achieved by monitoring the consumption of a single cell's contents upon its collisions with a microelectrode in the presence of surfactant. The electrochemical response between acute lymphoblastic lymphoma T-cells and healthy thymocytes differed by two orders of magnitude.

  5. Ultrasensitive Electrochemical Detection of mRNA Using Branched DNA Amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Xun; Liu, Guodong; Wang, Shengfu; Lin, Yuehe; Zhang, Aiguo; Zhang, Lurong; Ma, Yunqing

    2008-11-01

    We describe here an ultrasensitive electrochemical detection of m RNA protocol without RNA purification and PCR amplification. The new m RNA electrical detection capability is coupled to the amplification feature of branched DNA (bDNA) technology and with the nagnetic beads based electrochemical bioassay.

  6. Multiplexed electrochemical protein detection and translation to personalized cancer diagnostics.

    Science.gov (United States)

    Rusling, James F

    2013-06-04

    Measuring diagnostic panels of multiple proteins promises a new, personalized approach to early detection and therapy of diseases like cancer. Levels of biomarker proteins in patient serum can provide a continually updated record of disease status. Research in electrochemical detection of proteins has produced exquisitely sensitive approaches. Most utilize ELISA-like sandwich immunoassays incorporating various aspects of nanotechnology. Several of these ultrasensitive methodologies have been extended to microfluidic multiplexed protein detection, but engineered solutions are needed to measure more proteins in a single device from a small patient sample such as a drop of blood or tissue lysate. To achieve clinical or point-of-care (POC) use, simplicity and low cost are essential. In multiplexed microfluidic immunoassays, required reagent additions and washing steps pose a significant problem calling for creative engineering. A grand challenge is to develop a general cancer screening device to accurately measure 50-100 proteins in a simple, cost-effective fashion. This will require creative solutions to simplified reagent addition and multiplexing.

  7. A reduced graphene oxide based electrochemical biosensor for tyrosine detection.

    Science.gov (United States)

    Wei, Junhua; Qiu, Jingjing; Li, Li; Ren, Liqiang; Zhang, Xianwen; Chaudhuri, Jharna; Wang, Shiren

    2012-08-24

    In this paper, a 'green' and safe hydrothermal method has been used to reduce graphene oxide and produce hemin modified graphene nanosheet (HGN) based electrochemical biosensors for the determination of l-tyrosine levels. The as-fabricated HGN biosensors were characterized by UV-visible absorption spectra, fluorescence spectra, Fourier transform infrared spectroscopy (FTIR) spectra and thermogravimetric analysis (TGA). The experimental results indicated that hemin was successfully immobilized on the reduced graphene oxide nanosheet (rGO) through π-π interaction. TEM images and EDX results further confirmed the attachment of hemin on the rGO nanosheet. Cyclic voltammetry tests were carried out for the bare glass carbon electrode (GCE), the rGO electrode (rGO/GCE), and the hemin-rGO electrode (HGN/GCE). The HGN/GCE based biosensor exhibits a tyrosine detection linear range from 5 × 10(-7) M to 2 × 10(-5) M with a detection limitation of 7.5 × 10(-8) M at a signal-to-noise ratio of 3. The sensitivity of this biosensor is 133 times higher than that of the bare GCE. In comparison with other works, electroactive biosensors are easily fabricated, easily controlled and cost-effective. Moreover, the hemin-rGO based biosensors demonstrate higher stability, a broader detection linear range and better detection sensitivity. Study of the oxidation scheme reveals that the rGO enhances the electron transfer between the electrode and the hemin, and the existence of hemin groups effectively electrocatalyzes the oxidation of tyrosine. This study contributes to a widespread clinical application of nanomaterial based biosensor devices with a broader detection linear range, improved stability, enhanced sensitivity and reduced costs.

  8. Detection of 1,5-Anhydroglucitol by Electrochemical Impedance Spectroscopy

    Science.gov (United States)

    Adamson, Teagan L.; Cook, Curtiss B.

    2014-01-01

    Multiple markers are used to assess glycemic control in patients with diabetes mellitus (DM). New technology that permits simultaneous detection of multiple biomarkers combined with those used at the point of care indicative of glycemic control, including glycemic variability determined from 1,5-anhydroglucitol measurement, could provide better management and further insight into the disease. This platform was based on previous research involving glucose detection and uses electrochemical impedance spectroscopy to detect a range of 1,5-anhydroglucitol concentrations at an optimal binding frequency. The enzyme pyranose oxidase was fixed to gold electrodes while a sine wave of sweeping frequencies was induced in purified solutions and in variable presence of whole blood. The optimal binding frequency for the detection of 1,5-anhydroglucitol was found to be 3.71 kHz. The impedance response compared to the concentration of target present was found to have a logarithmic slope of 7.04 with an R-squared value of 0.96. This response includes 2 experimental sets, a single test of a low concentration range and a high concentration range with 5 replicates. The relative standard deviation of the high range varied from 28% to 27% from lowest to highest concentrations. Best detection in complex solutions was found in lower blood concentrations of 0.5% and 1%, but maintained relatively high accuracy in concentrations 5% and 10%. The sensor platform was successfully evaluated at a high dynamic range of 1,5-AG in purified solutions. In the presence of whole blood, lowest percentages yielded the best results indicating that filtering interferents may be necessary in final device architecture. PMID:24876587

  9. Electrochemical biosensors for rapid detection of Escherichia coli O157:H7.

    Science.gov (United States)

    Xu, Meng; Wang, Ronghui; Li, Yanbin

    2017-01-01

    Electrochemical biosensors have shown great promise in the development of rapid methods for the detection of foodborne pathogens and have been intensively studied over the past two decades. The scope of this review is to summarize the advancements made in the development of electrochemical biosensors for the rapid detection of one of the most common foodborne pathogens, Escherichia coli O157:H7. The article is intended to include different configurations of electrochemical biosensors based on the sensing principles and measured electrical parameters, as well as the latest improvements of technology in the progress of electrochemical biosensor development to detect E. coli O157:H7. By discussing the current and future trend based on some of excellent published literatures and reviews, this survey is hoped to illustrate a broad and comprehensive understanding of electrochemical biosensors for the detection of foodborne pathogens.

  10. A Chemically Synthesized Capture Agent Enables the Selective, Sensitive, and Robust Electrochemical Detection of Anthrax Protective Antigen

    Science.gov (United States)

    2014-08-01

    A Chemically Synthesized Capture Agent Enables the Selective, Sensitive, and Robust Electrochemical Detection of Anthrax Protective Antigen...A Chemically Synthesized Capture Agent Enables the Selective, Sensitive, and Robust Electrochemical Detection of Anthrax Protective Antigen...AND SUBTITLE A Chemically Synthesized Capture Agent Enables the Selective, Sensitive, and Robust Electrochemical Detection of Anthrax Protective

  11. 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.

  12. A compact multifunctional microfluidic platform for exploring cellular dynamics in real-time using electrochemical detection

    DEFF Research Database (Denmark)

    Zor, Kinga; Heiskanen, Arto; Caviglia, Claudia

    2014-01-01

    and electrochemical analysis platform with in-built fluid handling and detection, enabling complete cell based assays comprising on-line electrode cleaning, sterilization, surface functionalization, cell seeding, cultivation and electrochemical real-time monitoring of cellular dynamics. To demonstrate the versatility...

  13. Electrochemical impedance spectroscopy based-on interferon-gamma detection

    Science.gov (United States)

    Li, Guan-Wei; Kuo, Yi-Ching; Tsai, Pei-I.; Lee, Chih-Kung

    2014-03-01

    Tuberculosis (TB) is an ancient disease constituted a long-term menace to public health. According to World Health Organization (WHO), mycobacterium tuberculosis (MTB) infected nearly a third of people of the world. There is about one new TB occurrence every second. Interferon-gamma (IFN-γ) is associated with susceptibility to TB, and interferongamma release assays (IGRA) is considered to be the best alternative of tuberculin skin test (TST) for diagnosis of latent tuberculosis infection (LTBI). Although significant progress has been made with regard to the design of enzyme immunoassays for IFN-γ, adopting this assay is still labor-intensive and time-consuming. To alleviate these drawbacks, we used IFN-γ antibody to facilitate the detection of IFN-γ. An experimental verification on the performance of IGRA was done in this research. We developed two biosensor configurations, both of which possess high sensitivity, specificity, and rapid IFN-γ diagnoses. The first is the electrochemical method. The second is a circular polarization interferometry configuration, which incorporates two light beams with p-polarization and s-polarization states individually along a common path, a four photo-detector quadrature configuration to arrive at a phase modulated ellipsometer. With these two methods, interaction between IFN-γ antibody and IFN-γ were explored and presented in detail.

  14. Smart portable electrophoresis instrument based on multipurpose microfluidic chips with electrochemical detection.

    Science.gov (United States)

    Fernández-la-Villa, Ana; Sánchez-Barragán, Dámaso; Pozo-Ayuso, Diego F; Castaño-Álvarez, Mario

    2012-09-01

    A second generation of a battery-powered portable electrophoresis instrument for the use of ME with electrochemical detection was developed. As the first-generation, the main unit of the instrument (150 mm × 165 mm × 95 mm) consists of four-outputs high-voltage power supply (HVPS) with maximum voltage of 3 KV and acquisition system (bipotentiostat) containing 2-channels for dual electrochemical detection. A new reusable microfluidic platform was designed in order to incorporate the microchips with the portable instrument. In this case, the platform is integrated to the main unit of the instrument so that it is not necessary to have any external cable for the interconnection of both parts, making the use of the complete system easier. The new platform contains all the electrical connections for the HVPS and bipotentiostat, as well as fluidic ports for driving the solutions. The microfluidic electrophoresis instrument is controlled by means of a user-friendly interface from a computer. The possibility of wireless connection (Bluetooth®) allows the use of the instrument without any external cable improving the portability. Therefore, the second generation brings a more compact and integrated electrophoresis instrument for "in situ" applications using microfluidic chips in an easy way. The performance of the electrophoresis system was initially evaluated using single- and dual-channel SU-8/Pyrex microchips with different models of integrated electrodes including microelectrodes and interdigitated arrays. The method was tested in different analytical applications such as separation of neurotransmitters, chlorophenols, purine derivatives, vitamins, polyphenolic acids, and flavones.

  15. A Fully Integrated and Miniaturized Heavy-metal-detection Sensor Based on Micro-patterned Reduced Graphene Oxide

    National Research Council Canada - National Science Library

    Xuan, Xing; Hossain, Md Faruk; Park, Jae Yeong

    2016-01-01

    .... The fully integrated electrochemical micro-sensor was then measured and evaluated for the detection of cadmium and lead-heavy metal ions in an acetic-acid buffered solution using the square wave...

  16. Electrochemical Detection of a Dengue-related Oligonucleotide Sequence Using Ferrocenium as a Hybridization Indicator

    OpenAIRE

    José Luiz de Lima-Filho; Duarte Miguel França dos Prazeres; ernando Rodrigues Ribeiro Teles

    2007-01-01

    A simple method for electrochemical detection of a synthetic 20-bp oligonucleotide sequence related with dengue virus genome was developed. A complimentary DNA probe sequence was electrostatically immobilized onto a glassy carbon electrode modified with chitosan. Electrochemical detection of hybridization between probe and target was performed by cyclic voltammetry, using ferrocene (Fc+) as a hybridization label. After hybridization, the peak current response of Fc+ oxidation increased around...

  17. Design and Electrochemical Study of Platinum-Based Nanomaterials for Sensitive Detection of Nitric Oxide in Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Maduraiveeran Govindhan

    2016-11-01

    Full Text Available The extensive physiological and regulatory roles of nitric oxide (NO have spurred the development of NO sensors, which are of critical importance in neuroscience and various medical applications. The development of electrochemical NO sensors is of significant importance, and has garnered a tremendous amount of attention due to their high sensitivity and selectivity, rapid response, low cost, miniaturization, and the possibility of real-time monitoring. Nanostructured platinum (Pt-based materials have attracted considerable interest regarding their use in the design of electrochemical sensors for the detection of NO, due to their unique properties and the potential for new and innovative applications. This review focuses primarily on advances and insights into the utilization of nanostructured Pt-based electrode materials, such as nanoporous Pt, Pt and PtAu nanoparticles, PtAu nanoparticle/reduced graphene oxide (rGO, and PtW nanoparticle/rGO-ionic liquid (IL nanocomposites, for the detection of NO. The design, fabrication, characterization, and integration of electrochemical NO sensing performance, selectivity, and durability are addressed. The attractive electrochemical properties of Pt-based nanomaterials have great potential for increasing the competitiveness of these new sensors and open up new opportunities in the creation of novel NO-sensing technologies for biological and medical applications.

  18. A Mini-Electrochemical System with Integrated Micropipet Tip and Pencil Graphite Electrode for Measuring Cytotoxicity.

    Science.gov (United States)

    Wu, Dong-Mei; Guo, Xiao-Ling; Wang, Qian; Li, Jin-Lian; Cui, Ji-Wen; Zhou, Shi; Hao, Su-E

    2017-01-01

    A novel mini-electrochemical system has been developed for evaluating cytotoxicity of anticancer drugs based on trace cell samples. The mini-electrochemical system was integrated by using pencil graphite modified with threonine as working electrode, an Ag/AgCl reference electrode and a micropipet tip as electrochemical cell. The mini-electrochemical system dramatically reduces sample volumes from 500 μL in a traditional electrochemical system to 10 μL, and exhibits excellent electrocatalytic activity toward oxidation of purine from MCF-7 cells due to increased sensitivity provided by threonine. Moreover, the relationship between peak current and the cell concentration in the range from 3.0 × l0(3) to 7.0 × l0(6) cells/mL was studied, and a nonlinear exponential relationship between them was established over a wide concentration range. In evaluating the effect of anticancer drugs on cell viability, the results of drug cytotoxicity test based on cyclophosphamide were in close agreement with classical 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assays. The proposed device is so simple, cheap, and easy to operate that it could be applied to single-use applications. The mini-electrochemical system proved to be a useful tool and can be applied to electrochemical studies of cancer cells as well as other biological samples such as proteins and DNA.

  19. Electrochemical materials and processes in Si integrated circuit technology

    Energy Technology Data Exchange (ETDEWEB)

    Dubin, V.M. [Intel Corp., Components Research, Hillsboro, OR 97124 (United States)]. E-mail: valery.m.dubin@intel.com; Akolkar, R. [Intel Corp., Components Research, Hillsboro, OR 97124 (United States); Cheng, C.C. [Intel Corp., Components Research, Hillsboro, OR 97124 (United States); Chebiam, R. [Intel Corp., Components Research, Hillsboro, OR 97124 (United States); Fajardo, A. [Intel Corp., Components Research, Hillsboro, OR 97124 (United States); Gstrein, F. [Intel Corp., Components Research, Hillsboro, OR 97124 (United States)

    2007-02-10

    Various technical issues related to feature scaling and recent electrochemical technologies advances for on-chip copper interconnects at Intel are reviewed. Effects of additives on electroplating, as well as performance of novel Cu direct plating on ruthenium liner are discussed. An electroless cobalt capping layer of Cu lines, which led to increased electromigration resistance, has been characterized. The potential application of carbon nanotubes as future interconnects materials, their properties and controlled placement by using dielectrophoresis are also reviewed.

  20. 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.

  1. Electrochemical affinity biosensors for detection of mycotoxins: A review.

    Science.gov (United States)

    Vidal, Juan C; Bonel, Laura; Ezquerra, Alba; Hernández, Susana; Bertolín, Juan R; Cubel, Carlota; Castillo, Juan R

    2013-11-15

    This review discusses the current state of electrochemical biosensors in the determination of mycotoxins in foods. Mycotoxins are highly toxic secondary metabolites produced by molds. The acute toxicity of these results in serious human and animal health problems, although it has been only since early 1960s when the first studied aflatoxins were found to be carcinogenic. Mycotoxins affect a broad range of agricultural products, most important cereals and cereal-based foods. A majority of countries, mentioning especially the European Union, have established preventive programs to control contamination and strict laws of the permitted levels in foods. Official methods of analysis of mycotoxins normally requires sophisticated instrumentation, e.g. liquid chromatography with fluorescence or mass detectors, combined with extraction procedures for sample preparation. For about sixteen years, the use of simpler and faster analytical procedures based on affinity biosensors has emerged in scientific literature as a very promising alternative, particularly electrochemical (i.e., amperometric, impedance, potentiometric or conductimetric) affinity biosensors due to their simplicity and sensitivity. Typically, electrochemical biosensors for mycotoxins use specific antibodies or aptamers as affinity ligands, although recombinant antibodies, artificial receptors and molecular imprinted polymers show potential utility. This article deals with recent advances in electrochemical affinity biosensors for mycotoxins and covers complete literature from the first reports about sixteen years ago.

  2. Microfluidic Arrayed Lab-On-A-Chip for Electrochemical Capacitive Detection of DNA Hybridization Events.

    Science.gov (United States)

    Ben-Yoav, Hadar; Dykstra, Peter H; Bentley, William E; Ghodssi, Reza

    2017-01-01

    A microfluidic electrochemical lab-on-a-chip (LOC) device for DNA hybridization detection has been developed. The device comprises a 3 × 3 array of microelectrodes integrated with a dual layer microfluidic valved manipulation system that provides controlled and automated capabilities for high throughput analysis of microliter volume samples. The surface of the microelectrodes is functionalized with single-stranded DNA (ssDNA) probes which enable specific detection of complementary ssDNA targets. These targets are detected by a capacitive technique which measures dielectric variation at the microelectrode-electrolyte interface due to DNA hybridization events. A quantitative analysis of the hybridization events is carried out based on a sensing modeling that includes detailed analysis of energy storage and dissipation components. By calculating these components during hybridization events the device is able to demonstrate specific and dose response sensing characteristics. The developed microfluidic LOC for DNA hybridization detection offers a technology for real-time and label-free assessment of genetic markers outside of laboratory settings, such as at the point-of-care or in-field environmental monitoring.

  3. Polymer based biosensor for rapid electrochemical detection of virus infection of human cells

    DEFF Research Database (Denmark)

    Kiilerich-Pedersen, Katrine; Poulsen, Claus R.; Jain, Titoo

    2011-01-01

    The demand in the field of medical diagnostics for simple, cost efficient and disposable devices is growing. Here, we present a label free, all-polymer electrochemical biosensor for detection of acute viral disease. The dynamics of a viral infection in human cell culture was investigated in a micro...... fluidic system on conductive polymer PEDOT:TsO microelectrodes by electrochemical impedance spectroscopy and video time lapse microscopy.Employing this sensitive, real time electrochemical technique, we could measure the immediate cell response to cytomegalovirus, and detect an infection within 3h, which...... is several hours before the cytopathic effect is apparent with conventional imaging techniques. Atomic force microscopy and scanning ion conductance microscopy imaging consolidate the electrochemical measurements by demonstrating early virus induced changes in cell morphology of apparent programmed cell...

  4. CD/AuNPs/MWCNTs based electrochemical sensor for quercetin dual-signal detection.

    Science.gov (United States)

    Kan, Xianwen; Zhang, Tingting; Zhong, Min; Lu, Xiaojing

    2016-03-15

    A dual-signal strategy was developed in the present work for quercetin (QR) electrochemical recognition and detection. Mercapto-β-cyclodextrin (HS-β-CD) self-assembled on gold nanoparticles and multi-walled carbon nanotubes modified electrode surface to fabricate an electrochemical sensor. Scanning electron microscope, electrochemical impedance spectroscopy, and cyclic voltammetry were employed to characterize the preparation process of the sensor. Hydroquinone (HQ) was chosen as an electrochemical marker for QR detection due to its small molecular size for the formation of inclusion with HS-β-CD. The results of UV-vis and differential pulse voltammetry demonstrate that the added QR can replace the included HQ in CD cavities, resulting in the dual-signal in electrochemical experiments composed of the decrease of oxidized current of HQ and the increase of oxidized current of QR. Compared with the sensor for QR detection in the absence of HQ, the sensor based dual-signal strategy exhibited a higher sensitivity with a wider detection range from 5.0 × 10(-9) to 7.0 × 10(-6)mol/L. With good selectivity, reproducibility, and stability, the sensor was applied for real samples detection with satisfactory results. The proposed dual-signal strategy can be readily extended to the selective recognition and sensitive detection of other molecules.

  5. New advances in electrochemical biosensors for the detection of toxins: Nanomaterials, magnetic beads and microfluidics systems. A review

    Energy Technology Data Exchange (ETDEWEB)

    Reverté, Laia [IRTA, Carretera Poble Nou km. 5.5, 43540 Sant Carles de la Ràpita, Tarragona (Spain); Prieto-Simón, Beatriz [ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Future Industries Institute, University of South Australia, SA 5095 (Australia); Campàs, Mònica, E-mail: monica.campas@irta.cat [IRTA, Carretera Poble Nou km. 5.5, 43540 Sant Carles de la Ràpita, Tarragona (Spain)

    2016-02-18

    The use of nanotechnology in bioanalytical devices has special advantages in the detection of toxins of interest in food safety and environmental applications. The low levels to be detected and the small size of toxins justify the increasing number of publications dealing with electrochemical biosensors, due to their high sensitivity and design versatility. The incorporation of nanomaterials in their development has been exploited to further increase their sensitivity, providing simple and fast devices, with multiplexed capabilities. This paper gives an overview of the electrochemical biosensors that have incorporated carbon and metal nanomaterials in their configurations for the detection of toxins. Biosensing systems based on magnetic beads or integrated into microfluidics systems have also been considered because of their contribution to the development of compact analytical devices. The roles of these materials, the methods used for their incorporation in the biosensor configurations as well as the advantages they provide to the analyses are summarised. - Highlights: • Nanomaterials improve the performance of electrochemical biosensors. • Carbon nanomaterials can act as electrocatalysts or label supports in biosensors. • Metal nanomaterials can act as nanostructured supports or labels in biosensors. • Magnetic beads are exploited as immobilisation supports and/or label carriers.

  6. Recent advances in DNA-based electrochemical biosensors for heavy metal ion detection: A review.

    Science.gov (United States)

    Saidur, M R; Aziz, A R Abdul; Basirun, W J

    2017-04-15

    The presence of heavy metal in food chains due to the rapid industrialization poses a serious threat on the environment. Therefore, detection and monitoring of heavy metals contamination are gaining more attention nowadays. However, the current analytical methods (based on spectroscopy) for the detection of heavy metal contamination are often very expensive, tedious and can only be handled by trained personnel. DNA biosensors, which are based on electrochemical transduction, is a sensitive but inexpensive method of detection. The principles, sensitivity, selectivity and challenges of electrochemical biosensors are discussed in this review. This review also highlights the major advances of DNA-based electrochemical biosensors for the detection of heavy metal ions such as Hg(2+), Ag(+), Cu(2+) and Pb(2+).

  7. Neural Cell Chip Based Electrochemical Detection of Nanotoxicity

    Directory of Open Access Journals (Sweden)

    Md. Abdul Kafi

    2015-07-01

    Full Text Available Development of a rapid, sensitive and cost-effective method for toxicity assessment of commonly used nanoparticles is urgently needed for the sustainable development of nanotechnology. A neural cell with high sensitivity and conductivity has become a potential candidate for a cell chip to investigate toxicity of environmental influences. A neural cell immobilized on a conductive surface has become a potential tool for the assessment of nanotoxicity based on electrochemical methods. The effective electrochemical monitoring largely depends on the adequate attachment of a neural cell on the chip surfaces. Recently, establishment of integrin receptor specific ligand molecules arginine-glycine-aspartic acid (RGD or its several modifications RGD-Multi Armed Peptide terminated with cysteine (RGD-MAP-C, C(RGD4 ensure farm attachment of neural cell on the electrode surfaces either in their two dimensional (dot or three dimensional (rod or pillar like nano-scale arrangement. A three dimensional RGD modified electrode surface has been proven to be more suitable for cell adhesion, proliferation, differentiation as well as electrochemical measurement. This review discusses fabrication as well as electrochemical measurements of neural cell chip with particular emphasis on their use for nanotoxicity assessments sequentially since inception to date. Successful monitoring of quantum dot (QD, graphene oxide (GO and cosmetic compound toxicity using the newly developed neural cell chip were discussed here as a case study. This review recommended that a neural cell chip established on a nanostructured ligand modified conductive surface can be a potential tool for the toxicity assessments of newly developed nanomaterials prior to their use on biology or biomedical technologies.

  8. Electrochemical detection on electrowetting-on-dielectric digital microfluidic chip.

    Science.gov (United States)

    Karuwan, Chanpen; Sukthang, Kreeta; Wisitsoraat, Anurat; Phokharatkul, Ditsayut; Patthanasettakul, Viyapol; Wechsatol, Wishsanuruk; Tuantranont, Adisorn

    2011-06-15

    In this work, the use of three-electrode electrochemical sensing system with an electrowetting-on-dielectric (EWOD) digital microfluidic device is reported for quantitative analysis of iodide. T-junction EWOD mixer device was designed using arrays of 50-μm spaced square electrodes for mixing buffer reagent and analyte droplets. For fabrication of EWOD chips, 5-μm thick silver EWOD electrodes were formed on a glass substrate by means of sputtering and lift-off process. PDMS and Teflon thin films were then coated on the electrodes by spin coating to yield hydrophobic surface. An external three-electrode system consisting of Au working, Ag reference and Pt auxiliary wires were installed over EWOD electrodes at the end of T-junction mixer. In experiment, a few-microliter droplets of Tris buffer and iodide solutions were moved toward the mixing junction and transported toward electrochemical electrodes by EWOD process. A short processing time within seconds was achieved at EWOD applied voltage of 300V. The analyte droplets mixed with different concentrations were successfully analyzed by cyclic voltametry. Therefore, the combination of EWOD digital microfluidic and electrochemical sensing system has successfully been demonstrated for rapid chemical analysis with minimal reagent consumption.

  9. Electrochemical DNA sandwich assay with a lipase label for attomole detection of DNA

    DEFF Research Database (Denmark)

    Ferapontova, Elena; Hansen, Majken Nørgaard; Saunders, Aaron Marc

    2010-01-01

    A fast and sensitive electrochemical lipase-based sandwich hybridization assay for detection of attomole levels of DNA has been developed. A combination of magnetic beads, used for pre-concentration and bioseparation of the analyte with a lipase catalyst label allowed detection of DNA with a limit...

  10. Electrochemical behaviorof carbon paste electrode modified with Carbon Nanofibers: Application to detection of Bisphenol A

    Directory of Open Access Journals (Sweden)

    N.Achargui

    2016-12-01

    Full Text Available The electrochemical behavior of carbon paste electrode modified with carbon nanofibers has been studied using cyclic voltammetry (CV, electrochemical impedance spectroscopy (EIS and scaning electron microscopy. The response of modified electrodein ferroferricyanidesolutionshows reversible behavior and significant increment in current value compared to the bare CPE indicating that CNFs act as efficient electron mediator to catalyze reactions at the surface. The modified electrode has been used to study the electrochemical response of bisphenol Ausing different electrochemical techniques such as cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry and square wave voltammetry. The oxidation peak of BPA was observed at about 0.53 V in phosphate buffer solution at pH 6.7. The oxidation peak current of BPA varied linearly with concentration over a wide range of 5µmol L-1 to 400 µmol L-1 and the detection limit of this method was found to be 0.55 µmol L-1

  11. Synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel for electrochemical detection of dopamine.

    Science.gov (United States)

    Li, Ruiyi; Yang, Tingting; Li, Zaijun; Gu, Zhiguo; Wang, Guangli; Liu, Junkang

    2017-02-15

    Integration of noble metal nanomaterials on graphene nanosheets potentially paves one way to improve their electronic, chemical and electrochemical properties. The study reported synthesis of palladium@gold nanoalloys/nitrogen and sulphur-functionalized multiple graphene aerogel composite (Pd@Au/N,S-MGA). The as-prepared composite offers a well-defined three-dimensional architecture with rich of mesopores. The Pd@Au nanoalloys were dispersed on the graphene framework networks and their active sites were fully exposed. The unique structure achieves to ultra high electron/ion conductivity, electrocatalytic activity and structural stability. The sensor based on the Pd@Au/N,S-MGA creates ultrasensitive electrochemical response towards dopamine due to significantly electrochemical synergy between Pd, Au and N,S-MGA. Its differential pulse voltammetric signal linearly increases with the increase of dopamine concentration in the range from 1.0 × 10(-9) M to 4.0 × 10(-5) M with the detection limit of 3.6 × 10(-10) M (S/N = 3). The analytical method provides the advantage of sensitivity, reproducibility, rapidity and long-term stability. It has been successfully applied in the detection of trace dopamine in biological samples. The study also opens a window on the electronic properties of graphene aerogel and metal nanomaterials as well their nanohybrids to meet needs of further applications as nanoelectronics in diagnosis, bioanalysis and catalysis.

  12. Electrochemical detection of Hg (II) ions using EDTA-PANI/SWNTs nanocomposite modified SS electrode

    Science.gov (United States)

    Deshmukh, M. A.; Patil, H. K.; Shirsat, M. D.; Ramanavicius, A.

    2017-05-01

    Detection of Hg (II) ions using EDTA modified polyaniline (PANI) and single walled carbon nanotubes (SWNTs) nanocomposite (PANI/SWNTs) was performed electrochemically via cyclic voltammetry (CV) technique. Dodecyl benzene sulphonic next step, PANI/SWNTs nanocomposite was modified acid sodium salt (DBSA) was used as a surfactant during this synthesis to get uniform suspension SWNTs. In the by EDTA solution containing crosslinking agent 1-ethyl-3(3-(dimethylamino) propyl) - carbodiimide (EDC) utilizing dip coating technique. The sensitivity of EDTA modified PANI/SWNTs nanocomposite towards Hg (II) ions was investigated. Differential pulse voltammetry (DPV) technique was applied for the electrochemical detection of Hg (II) ions.

  13. A New Dual-electrode and Multi-channel Electrochemical DetectionSystem for Capillary Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    Bing Yi YANG; Jin Yuan MO; Rong LAI

    2004-01-01

    A new type of dual-electrode and multi-channel electrochemical detection technology for capillary electrophoresis is described in this paper. Two detectors(the amperometric detector and the conductometric detector)or two conductometric detectors are connected to the same capillary electrophoresis system. The whole system possesses the advantages of the two electrochemical detectors including sparing time,improving the analytical speed and expanding the sample range.The working electrode and detector cell are handled easily.The system was applied to sample detection with satisfactory results.

  14. Determination of urinary vanillylmandelic acid by liquid chromatography with electrochemical detection.

    Science.gov (United States)

    Moleman, P; Borstrok, J J

    1983-05-01

    We describe an improved method for the assay of urinary vanillylmandelic acid by "high-performance" liquid chromatography, with electrochemical detection. A 1-mL aliquot of urine is acidified and extracted with ethyl acetate, then the ethyl acetate extract is extracted with phosphate buffer, pH 8.5. An acidified aliquot of the phosphate extract is injected into a reversed-phase column and vanillylmandelic acid is detected electrochemically. The between-day CV is 5-6% for concentrations ranging from 10 to 75 mumol/L. We also discuss the critical steps for extraction and calibration.

  15. Electrochemical impedance spectroscopy in chromatography paper and its application to latex bead detection

    Science.gov (United States)

    Iwahara, Shohei; Miki, Masashi; Hori, Fumitaka; Uno, Shigeyasu

    2014-01-01

    The principle of the quantitative immunochromatographic strip test (IST) is proposed. Electrochemical impedance spectroscopy is shown to be capable of detecting latex beads in chromatography paper, where latex beads can serve as a label in IST. Measurements to examine the impedance changes in the absence and presence of latex beads are conducted. In the presence of latex beads, an increase of 12.5% in the bulk solution resistance is observed. This indicates that the latex-bead-labeled antigen-antibody complex can be detected electrochemically by actual IST.

  16. Fast and sensitive detection of foodborne pathogen using electrochemical impedance analysis, urease catalysis and microfluidics.

    Science.gov (United States)

    Chen, Qi; Wang, Dan; Cai, Gaozhe; Xiong, Yonghua; Li, Yuntao; Wang, Maohua; Huo, Huiling; Lin, Jianhan

    2016-12-15

    Early screening of pathogenic bacteria is a key to prevent and control of foodborne diseases. In this study, we developed a fast and sensitive bacteria detection method integrating electrochemical impedance analysis, urease catalysis with microfluidics and using Listeria as model. The Listeria cells, the anti-Listeria monoclonal antibodies modified magnetic nanoparticles (MNPs), and the anti-Listeria polyclonal antibodies and urease modified gold nanoparticles (AuNPs) were incubated in a fluidic separation chip with active mixing to form the MNP-Listeria-AuNP-urease sandwich complexes. The complexes were captured in the separation chip by applying a high gradient magnetic field, and the urea was injected to resuspend the complexes and hydrolyzed under the catalysis of the urease on the complexes into ammonium ions and carbonate ions, which were transported into a microfluidic detection chip with an interdigitated microelectrode for impedance measurement to determine the amount of the Listeria cells. The capture efficiency of the Listeria cells in the separation chip was ∼93% with a shorter time of 30min due to the faster immuno-reaction using the active magnetic mixing. The changes on both impedance magnitude and phase angle were demonstrated to be able to detect the Listeria cells as low as 1.6×10(2)CFU/mL. The detection time was reduced from original ∼2h to current ∼1h. The recoveries of the spiked lettuce samples ranged from 82.1% to 89.6%, indicating the applicability of this proposed biosensor. This microfluidic impedance biosensor has shown the potential for online, automatic and sensitive bacteria separation and detection.

  17. Automated microfluidic platform of bead-based electrochemical immunosensor integrated with bioreactor for continual monitoring of cell secreted biomarkers.

    Science.gov (United States)

    Riahi, Reza; Shaegh, Seyed Ali Mousavi; Ghaderi, Masoumeh; Zhang, Yu Shrike; Shin, Su Ryon; Aleman, Julio; Massa, Solange; Kim, Duckjin; Dokmeci, Mehmet Remzi; Khademhosseini, Ali

    2016-04-21

    There is an increasing interest in developing microfluidic bioreactors and organs-on-a-chip platforms combined with sensing capabilities for continual monitoring of cell-secreted biomarkers. Conventional approaches such as ELISA and mass spectroscopy cannot satisfy the needs of continual monitoring as they are labor-intensive and not easily integrable with low-volume bioreactors. This paper reports on the development of an automated microfluidic bead-based electrochemical immunosensor for in-line measurement of cell-secreted biomarkers. For the operation of the multi-use immunosensor, disposable magnetic microbeads were used to immobilize biomarker-recognition molecules. Microvalves were further integrated in the microfluidic immunosensor chip to achieve programmable operations of the immunoassay including bead loading and unloading, binding, washing, and electrochemical sensing. The platform allowed convenient integration of the immunosensor with liver-on-chips to carry out continual quantification of biomarkers secreted from hepatocytes. Transferrin and albumin productions were monitored during a 5-day hepatotoxicity assessment in which human primary hepatocytes cultured in the bioreactor were treated with acetaminophen. Taken together, our unique microfluidic immunosensor provides a new platform for in-line detection of biomarkers in low volumes and long-term in vitro assessments of cellular functions in microfluidic bioreactors and organs-on-chips.

  18. Automated microfluidic platform of bead-based electrochemical immunosensor integrated with bioreactor for continual monitoring of cell secreted biomarkers

    Science.gov (United States)

    Riahi, Reza; Shaegh, Seyed Ali Mousavi; Ghaderi, Masoumeh; Zhang, Yu Shrike; Shin, Su Ryon; Aleman, Julio; Massa, Solange; Kim, Duckjin; Dokmeci, Mehmet Remzi; Khademhosseini, Ali

    2016-04-01

    There is an increasing interest in developing microfluidic bioreactors and organs-on-a-chip platforms combined with sensing capabilities for continual monitoring of cell-secreted biomarkers. Conventional approaches such as ELISA and mass spectroscopy cannot satisfy the needs of continual monitoring as they are labor-intensive and not easily integrable with low-volume bioreactors. This paper reports on the development of an automated microfluidic bead-based electrochemical immunosensor for in-line measurement of cell-secreted biomarkers. For the operation of the multi-use immunosensor, disposable magnetic microbeads were used to immobilize biomarker-recognition molecules. Microvalves were further integrated in the microfluidic immunosensor chip to achieve programmable operations of the immunoassay including bead loading and unloading, binding, washing, and electrochemical sensing. The platform allowed convenient integration of the immunosensor with liver-on-chips to carry out continual quantification of biomarkers secreted from hepatocytes. Transferrin and albumin productions were monitored during a 5-day hepatotoxicity assessment in which human primary hepatocytes cultured in the bioreactor were treated with acetaminophen. Taken together, our unique microfluidic immunosensor provides a new platform for in-line detection of biomarkers in low volumes and long-term in vitro assessments of cellular functions in microfluidic bioreactors and organs-on-chips.

  19. Compact Electrochemical System Using On-Chip Sensor Electrodes and Integrated Devices

    Science.gov (United States)

    Yamazaki, Tomoyuki; Ikeda, Takaaki; Ishida, Makoto; Sawada, Kazuaki

    2011-04-01

    We report a compact electrochemical sensing system to implement cyclic voltammetry. This type of sensor needs a working electrode, counter electrode, and reference electrode, all of which were integrated on a single chip. The electrochemical system also needs a potentiostat and an input voltage-generating circuit, which were developed using on-chip active devices and a few discrete passive components. This is the first sensor system incorporating electrode-side input voltage generation for electrochemical measurements using an on-chip operational amplifier, which replaces a bulky external voltage controller. A continuous cyclic voltammetry measurement was conducted with a well-studied ferricyanide solution to demonstrate the operation of the intelligent sensor chip. A clear peak was observed and linearity to the target chemical concentration was obtained between the peak height and concentration of the ferricyanide solution. With potential for mass production and small size, this sensor chip could be the best candidate to realize point-of-care testing. This sensor chip is a milestone of a fully integrated electrochemical sensor chip.

  20. Electrochemical impedance immunosensor for the detection of cardiac biomarker Myogobin (Mb) in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Rajesh, E-mail: rajesh_csir@yahoo.com; Sharma, V.; Tanwar, V.K.; Mishra, S.K.; Biradar, A.M.

    2010-11-30

    A label-free, electrochemical impedance immunosensor based on surface modified thin flat gold wire electrode is reported for the quantitative detection of cardiac biomarker Myoglobin in aqueous solution. The protein antibody, ab-Mb, was covalently immobilized through a self assembled monolayer of 11-mercaptoundecanoic acid (MUA) and 3-mercapto propionic acid (MPA) via carbodiimide coupling reaction using N-(3-dimethylaminopropyl)-N'-ethyl carbodiimide hydrochloride (EDC) and N-Hydroxy Succinamide (NHS). The immunosensor (ab-Mb/MUA-MPA/Au) was characterized by electrochemical techniques. The electrochemical performance of the immunosensor was studied by electrochemical impedance spectroscopy. The immunosensor showed an increased electrontransfer resistance on coupling with biomarker protein antigen, ag-Mb, in the presence of a redox probe [Fe (CN){sub 6}]{sup 3-/4-}. The modified Au electrode immunosensor exhibits an electrochemical impedance response to antigen, ag-Mb concentrations in a linear range from 10 ng to 650 ng mL{sup -1} with a lowest detection limit of 5.2 ng mL{sup -1}.

  1. Label-Free Toxin Detection by Means of Time-Resolved Electrochemical Impedance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Paul Takhistov

    2010-01-01

    Full Text Available The real-time detection of trace concentrations of biological toxins requires significant improvement of the detection methods from those reported in the literature. To develop a highly sensitive and selective detection device it is necessary to determine the optimal measuring conditions for the electrochemical sensor in three domains: time, frequency and polarization potential. In this work we utilized a time-resolved electrochemical impedance spectroscopy for the detection of trace concentrations of Staphylococcus enterotoxin B (SEB. An anti-SEB antibody has been attached to the nano-porous aluminum surface using 3-aminopropyltriethoxysilane/glutaraldehyde coupling system. This immobilization method allows fabrication of a highly reproducible and stable sensing device. Using developed immobilization procedure and optimized detection regime, it is possible to determine the presence of SEB at the levels as low as 10 pg/mL in 15 minutes.

  2. Label-Free Toxin Detection by Means of Time-Resolved Electrochemical Impedance Spectroscopy

    Science.gov (United States)

    Chai, Changhoon; Takhistov, Paul

    2010-01-01

    The real-time detection of trace concentrations of biological toxins requires significant improvement of the detection methods from those reported in the literature. To develop a highly sensitive and selective detection device it is necessary to determine the optimal measuring conditions for the electrochemical sensor in three domains: time, frequency and polarization potential. In this work we utilized a time-resolved electrochemical impedance spectroscopy for the detection of trace concentrations of Staphylococcus enterotoxin B (SEB). An anti-SEB antibody has been attached to the nano-porous aluminum surface using 3-aminopropyltriethoxysilane/glutaraldehyde coupling system. This immobilization method allows fabrication of a highly reproducible and stable sensing device. Using developed immobilization procedure and optimized detection regime, it is possible to determine the presence of SEB at the levels as low as 10 pg/mL in 15 minutes. PMID:22315560

  3. Analysis of Ascorbic Acid in Single Human Neutrophils by Electrochemical Detection

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Ascorbic acid in individual human neutrophils was determined by capillary zone electrophoresis with electrochemical detection. In order to overcome the influence of the adsorption of the substances in cells on the inner surface wall of the capillary on the migration time and the number of theoretical plates, a procedure for treating capillaries has been described.

  4. Target-specific capture enhances sensitivity of electrochemical detection of bacterial pathogens.

    Science.gov (United States)

    Patel, Mayank; Gonzalez, Rodrigo; Halford, Colin; Lewinski, Michael A; Landaw, Elliot M; Churchill, Bernard M; Haake, David A

    2011-12-01

    We report the concentration and purification of bacterial 16S rRNA by the use of a biotinylated DNA target-specific capture (TSC) probe. For both cultivated bacterial and urine specimens from urinary tract infection patients, TSC resulted in a 5- to 8-fold improvement in the sensitivity of bacterial detection in a 16S rRNA electrochemical sensor assay.

  5. Electrochemical detection of single molecules using abiotic nanopores having electrically tunable dimensions

    Science.gov (United States)

    Sansinena, Jose-Maria; Redondo, Antonio; Olazabal, Virginia; Hoffbauer, Mark A.; Akhadov, Elshan A.

    2009-12-29

    A barrier structure for use in an electrochemical stochastic membrane sensor for single molecule detection. The sensor is based upon inorganic nanopores having electrically tunable dimensions. The inorganic nanopores are formed from inorganic materials and an electrically conductive polymer. Methods of making the barrier structure and sensing single molecules using the barrier structure are also described.

  6. A novel M-shape electrochemical aptasensor for ultrasensitive detection of tetracyclines.

    Science.gov (United States)

    Taghdisi, Seyed Mohammad; Danesh, Noor Mohammad; Ramezani, Mohammad; Abnous, Khalil

    2016-11-15

    Analytical techniques for detection and quantitation of tetracyclines in food products are greatly in demand. In this study, a novel electrochemical aptasensor was designed for ultrasensitive and selective detection of tetracyclines, based on M-shape structure of aptamer (Apt)-complementary strands of aptamer (CSs) complex, exonuclease I (Exo I) and gold electrode. The aptasensor was developed to make a noticeable electrochemical difference in the absence and presence of tetracycline. In the absence of tetracycline, the M-shape structure, which acts as a gate and barrier for the access of redox probe to the surface of gold electrode remains intact, leading to a weak electrochemical signal. Upon addition of tetracycline, Apt leaves CSs, resulting in disassembly of M-shape structure and following the addition of Exo I, a strong electrochemical signal was observed. The developed analytical assay indicated high selectivity toward tetracycline with a limit of detection (LOD) as low as 450 pM. Moreover, the designed aptasensor was effectively used for the detection of tetracycline in milk and serum samples with LODs of 740 and 710 pM, respectively.

  7. Electrochemical detection of single molecules using abiotic nanopores having electrically tunable dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Sansinena, Jose-Maria; Redondo, Antonio; Olazabal, Virginia; Hoffbauer, Mark A.

    2017-09-12

    A barrier structure for use in an electrochemical stochastic membrane sensor for single molecule detection. The sensor is based upon inorganic nanopores having electrically tunable dimensions. The inorganic nanopores are formed from inorganic materials and an electrically conductive polymer. Methods of making the barrier structure and sensing single molecules using the barrier structure are also described.

  8. Electrochemical detection of single molecules using abiotic nanopores having electrically tunable dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Sansinena, Jose-Maria; Redondo, Antonio; Olazabal, Virginia; Hoffbauer, Mark A.; Akhadov, Elshan A.

    2017-07-18

    A barrier structure for use in an electrochemical stochastic membrane sensor for single molecule detection. The sensor is based upon inorganic nanopores having electrically tunable dimensions. The inorganic nanopores are formed from inorganic materials and an electrically conductive polymer. Methods of making the barrier structure and sensing single molecules using the barrier structure are also described.

  9. Electrochemical OFF-ON ratiometric chemodosimeters for the selective and rapid detection of fluoride.

    Science.gov (United States)

    Mani, Veerappan; Li, Wen-Yung; Gu, Jiun-An; Lin, Chun-Mao; Huang, Sheng-Tung

    2015-01-01

    We have described two "OFF-ON electrochemical latent ratiometric redox chemodosimeters", 1,4-Bis(tert-butyldimethylsiloxy)benzene (H2Q') and 1,4-Bis (tert-butyldimet hylsiloxy)-2-methoxybenzene (MH2Q') for the selective detection of inorganic fluoride. The electrochemical signals of hydroquinone (H2Q) and o-methoxy hydroquinone (MH2Q) within this latent redox probes (H2Q' and MH2Q') were completely masked by protecting their hydroxyl group as silylether (OFF state). The externally added fluoride ions triggered the deprotection of H2Q' and MH2Q' and unmasked the electrochemical properties of H2Q and MH2Q respectively. The electrochemical reporters (H2Q and MH2Q) presented a pair of redox peaks at the electrode surface (ON state) and the peak currents are linearly dependent with the concentration of fluoride which leading to the ratiometric detection of fluoride. The limit of detection (signal-to-noise ratio=3) observed for the probes are 23.8 µM and 2.38 µM for H2Q' and MH2Q' respectively. The deprotection is highly selective for fluoride over other anions investigated. The probes are highly stable and the proposed approach offers rapid response time and promising practical applicability. The proposed strategy holds great promise for the commencement of new H2Q based electrochemical probes by tuning the electrochemical behavior of H2Q. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Carbide-Derived Carbon Films for Integrated Electrochemical Energy Storage

    Science.gov (United States)

    Heon, Min

    Active RFID tags, which can communicate over tens or even hundreds of meters, MEMS devices of several microns in size, which are designed for the medical and pharmaceutical purposes, and sensors working in wireless monitoring systems, require microscale power sources that are able to provide enough energy and to satisfy the peak power demands in those applications. Supercapacitors have not been an attractive candidate for micro-scale energy storage, since most nanoporous carbon electrode materials are not compatible with micro-fabrication techniques and have failed to meet the requirements of high volumetric energy density and small form factor for power supplies for integrated circuits or microelectronic devices or sensors. However, supercapacitors can provide high power density, because of fast charging/discharging, which can enable self-sustaining micro-modules when combined with energy-harvesting devices, such as solar cell, piezoelectric or thermoelectric micro-generators. In this study, carbide-derived carbon (CDC) films were synthesized via vacuum decomposition of carbide substrates and gas etching of sputtered carbide thin films. This approach allowed manufacturing of porous carbon films on SiC and silicon substrates. CDC films were studied for micro-supercapacitor electrodes, and showed good double layer capacitance. Since the gas etching technique is compatible with conventional micro-device fabrication processes, it can be implemented to manufacture integrated on-chip supercapacitors on silicon wafers.

  11. In-Channel-Grown Polypyrrole Nanowire for the Detection of DNA Hybridization in an Electrochemical Microfluidic Biosensor

    Directory of Open Access Journals (Sweden)

    Thi Luyen Tran

    2015-01-01

    Full Text Available A triple electrode setup with a Pt pseudo-reference electrode integrated in a polydimethylsiloxane- (PDMS- based microchamber was designed and fabricated. The integrated electrodes were deposited onto SiO2/Si substrate by sputtering. The PDMS microchamber was patterned using an SU-8 mold and sealed with electrodes in oxygen plasma. Polypyrrole nanowires (PPy NWs were electrochemically grown in situ at an accurate position of the working electrode in the sealed microchamber instead of in an open system. The DNA probe sequences were simply introduced into the channel to form bonds with the nanowires. A detection limit of 20 pM was achieved using a lock-in amplifier. The electrochemical characteristics produced by the hybridization of DNA strands in the microchamber showed a good signal/noise ratio and high sensitivity. Measurement of the DNA sensor in narrow space also required much less volume of the analytical sample compared with that in an open measuring cell. Results showed that this simple system can potentially fabricate nanostructures and detect bio/chemical molecules in a sealed system.

  12. Capillary electrophoresis-electrochemical detection microchip device and supporting circuits

    Science.gov (United States)

    Jackson, Douglas J.; Roussel, Jr., Thomas J.; Crain, Mark M.; Baldwin, Richard P.; Keynton, Robert S.; Naber, John F.; Walsh, Kevin M.; Edelen, John. G.

    2008-03-18

    The present invention is a capillary electrophoresis device, comprising a substrate; a first channel in the substrate, and having a buffer arm and a detection arm; a second channel in the substrate intersecting the first channel, and having a sample arm and a waste arm; a buffer reservoir in fluid communication with the buffer arm; a waste reservoir in fluid communication with the waste arm; a sample reservoir in fluid communication with the sample arm; and a detection reservoir in fluid communication with the detection arm. The detection arm and the buffer arm are of substantially equal length.

  13. Off surface matrix based on-chip electrochemical biosensor platform for protein biomarker detection in undiluted serum.

    Science.gov (United States)

    Arya, Sunil K; Kongsuphol, Patthara; Park, Mi Kyoung

    2017-06-15

    The manuscript describes a concept of using off surface matrix modified with capturing biomolecule for on-chip electrochemical biosensing. 3D matrix made by laser engraving of polymethyl methacrylate (PMMA) sheet as off surface matrix was integrated in very close vicinity of the electrode surface. Laser engraving and holes in PMMA along with spacing from surface provide fluidic channel and incubation chamber. Covalent binding of capturing biomolecule (anti-TNF-α antibody) on off-surface matrix was achieved via azide group activity of 4-fluoro-3-nitro-azidobenzene (FNAB), which act as cross-linker and further covalently binds to anti-TNF-α antibody via thermal reaction. Anti-TNF-α/FNAB/PMMA matrix was then integrated over comb structured gold electrode array based sensor chip. Separate surface modification followed by integration of sensor helped to prevent the sensor chip surface from fouling during functionalization. Nonspecific binding was prevented using starting block T20 (PBS). Results for estimating protein biomarker (TNF-α) in undiluted serum using Anti-TNF-α/FNAB/PMMA/Au reveal that system can detect TNF-α in 100pg/ml to 100ng/ml range with high sensitivity of 119nA/(ng/ml), with negligible interference from serum proteins and other cytokines. Thus, use of off surface matrix may provide the opportunity to electrochemically sense biomarkers sensitively to ng/ml range with negligible nonspecific binding and false signal in undiluted serum.

  14. Development of an Automated DNA Detection System Using an Electrochemical DNA Chip Technology

    Science.gov (United States)

    Hongo, Sadato; Okada, Jun; Hashimoto, Koji; Tsuji, Koichi; Nikaido, Masaru; Gemma, Nobuhiro

    A new compact automated DNA detection system Genelyzer™ has been developed. After injecting a sample solution into a cassette with a built-in electrochemical DNA chip, processes from hybridization reaction to detection and analysis are all operated fully automatically. In order to detect a sample DNA, electrical currents from electrodes due to an oxidization reaction of electrochemically active intercalator molecules bound to hybridized DNAs are detected. The intercalator is supplied as a reagent solution by a fluid supply unit of the system. The feasibility test proved that the simultaneous typing of six single nucleotide polymorphisms (SNPs) associated with a rheumatoid arthritis (RA) was carried out within two hours and that all the results were consistent with those by conventional typing methods. It is expected that this system opens a new way to a DNA testing such as a test for infectious diseases, a personalized medicine, a food inspection, a forensic application and any other applications.

  15. Dual amplified electrochemical immunosensor for highly sensitive detection of Pantoea stewartii sbusp. stewartii.

    Science.gov (United States)

    Zhao, Yuan; Liu, Liqiang; Kong, Dezhao; Kuang, Hua; Wang, Libing; Xu, Chuanlai

    2014-12-10

    Accurate and highly sensitive detection of Pantoea stewartii sbusp. stewartii-NCPPB 449 (PSS) is urgently required for international shipments due to tremendous agricultural economic losses. Herein, a dual amplified electrochemical sandwich immunosensor for PSS detection was developed, utilizing the good specificity and low cost of electrochemical immunoassay, the favorable conductivity and large specific surface area of gold nanoparticles (Au NPs), and the excellent catalytic ability of and horseradish peroxidase (HRP). A linear curve between current response and PSS concentration was established, and the limit of detection (LOD) was 7.8 × 10(3) cfu/mL, which is 20 times lower than that for conventional enzyme-linked immunosorbent assay (ELISA). This strategy is a useful approach for the highly sensitive detection of plant pathogenic bacterium.

  16. Sensitive electrochemical detection of horseradish peroxidase at disposable screen-printed carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ai Cheng; Liu, Guodong; Heng, Chew-Kiat; Tan, Swee-Nign; Lim, Tit-Meng; Lin, Yuehe

    2008-09-10

    A rapid, simple and sensitive electrochemical assay of horseradish peroxidase (HRP) performed on disposable screen-printed carbon electrode was developed. HRP activities were monitored by square-wave voltammetric (SWV) measuring the electroactive enzymatic product in the presence of o-aminophenol and hydrogen peroxide substrate solution. SWV analysis demonstrated a greater sensitivity and shorter analysis time than the widely used amperometric and differential-pulsed voltammetric methods. The voltammetric characteristics of substrate and enzymatic product as well as the parameters of SWV analysis were optimized. Under optimized conditions, a linear response for HRP from 0.003 - 0.1 U/mL and a detection limit of 0.002 U/mL (1.25×10-15 mol in 25 µL) were obtained with a good precision (RSD = 8%; n = 6). This rapid and sensitive HRP assay with microliters-assay volume could be readily integrated to portable devices and point-of-care (POC) diagnosis applications.

  17. Recent Advance in the Electrochemical Detection of Sulphide and Sulphhydryl Species

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This article aims at providing a critical review of some most recent developments in the electrochemical detection and measurement of hydrogen sulphide and the related species, which are of great significance to a variety of industries and in environmental moitoring. The molecular recognition processes are initiated by using either an organic precursor or a catalytic complex, leading to extensive ranges of detection. A series of advanced chemical and simulation techniques are used to probe the mechanistic details of the analytical chemistry involved.

  18. Identification of pathogenic microbial cells and spores by electrochemical detection on a biochip

    OpenAIRE

    Andresen Heiko; Gabig-Ciminska Magdalena; Albers Joerg; Hintsche Rainer; Enfors Sven-Olof

    2004-01-01

    Abstract Background Bacillus cereus constitutes a significant cause of acute food poisoning in humans. Despite the recent development of different detection methods, new effective control measures and better diagnostic tools are required for quick and reliable detection of pathogenic micro-organisms. Thus, the objective of this study was to determine a simple method for rapid identification of enterotoxic Bacillus strains. Here, a special attention is given to an electrochemical biosensor sin...

  19. Integrating electrochemical oxidation into forward osmosis process for removal of trace antibiotics in wastewater.

    Science.gov (United States)

    Liu, Pengxiao; Zhang, Hanmin; Feng, Yujie; Shen, Chao; Yang, Fenglin

    2015-10-15

    During the rejection of trace pharmaceutical contaminants from wastewater by forward osmosis (FO), disposal of the FO concentrate was still an unsolved issue. In this study, by integrating the advantages of forward osmosis and electrochemical oxidation, a forward osmosis process with the function of electrochemical oxidation (FOwEO) was established for the first time to achieve the aim of rejection of trace antibiotics from wastewater and treatment of the concentrate at the same time. Results demonstrated that FOwEO (current density J=1 mA cm(-2)) exhibited excellent rejections of antibiotics (>98%) regardless of different operation conditions, and above all, antibiotics in the concentrate were well degraded (>99%) at the end of experiment (after 3h). A synergetic effect between forward osmosis and electrochemical oxidation was observed in FOwEO, which lies in that antibiotic rejections by FO were enhanced due to the degradation of antibiotics in the concentrate, while the electrochemical oxidation capacity was improved in the FOwEO channel, of which good mass transfer and the assist of indirect oxidation owing to the reverse NaCl from draw solution were supposed to be the mechanism. This study demonstrated that the FOwEO has the capability to thoroughly remove trace antibiotics from wastewater.

  20. A miniaturized silicon based device for nucleic acids electrochemical detection

    Directory of Open Access Journals (Sweden)

    Salvatore Petralia

    2015-12-01

    The system and the method here reported offer better advantages in term of analytical performances compared to the standard commercial optical-based real-time PCR systems, with the additional incomes of being potentially cheaper and easier to integrate in a miniaturized device.

  1. An electrochemical immunosensor based on interdigitated array microelectrode for the detection of chlorpyrifos.

    Science.gov (United States)

    Cao, Yaoyao; Sun, Xia; Guo, Yemin; Zhao, Wenping; Wang, Xiangyou

    2015-02-01

    An electrochemical immunosensor based on interdigitated array microelectrodes (IDAMs) was developed for sensitive, specific and rapid detection of chlorpyrifos. Anti-chlorpyrifos monoclonal antibodies were orientedly immobilized onto the gold microelectrode surface through protein A. Chlorpyrifos were then captured by the immobilized antibody, resulting in an impedance change in the IDAMs surface. Electrochemical impedance spectroscopy was used in conjunction with the fabricated sensor to detect chlorpyrifos. Under optimum conditions, the impedance value change of chlorpyrifos was proportional to its concentrations in the range of 10(0)-10(5) ng/mL. The detection limit was found to be 0.014 ng/mL for chlorpyrifos. The proposed chlorpyrifos immunosensor could be used as a screening method in pesticide determination for the analysis of environmental, agricultural and pharmaceutical samples due to its rapidity, sensitivity and low cost.

  2. Screen Printed Carbon Electrode Based Electrochemical Immunosensor for the Detection of Dengue NS1 Antigen

    Directory of Open Access Journals (Sweden)

    Om Parkash

    2014-11-01

    Full Text Available An electrochemical immunosensor modified with the streptavidin/biotin system on screen printed carbon electrodes (SPCEs for the detection of the dengue NS1 antigen was developed in this study. Monoclonal anti-NS1 capture antibody was immobilized on streptavidin-modified SPCEs to increase the sensitivity of the assay. Subsequently, a direct sandwich enzyme linked immunosorbent assay (ELISA format was developed and optimized. An anti-NS1 detection antibody conjugated with horseradish peroxidase enzyme (HRP and 3,3,5,5'-tetramethybezidine dihydrochloride (TMB/H2O2 was used as an enzyme mediator. Electrochemical detection was conducted using the chronoamperometric technique, and electrochemical responses were generated at −200 mV reduction potential. The calibration curve of the immunosensor showed a linear response between 0.5 µg/mL and 2 µg/mL and a detection limit of 0.03 µg/mL. Incorporation of a streptavidin/biotin system resulted in a well-oriented antibody immobilization of the capture antibody and consequently enhanced the sensitivity of the assay. In conclusion, this immunosensor is a promising technology for the rapid and convenient detection of acute dengue infection in real serum samples.

  3. Electrochemical chip-based genomagnetic assay for detection of high-risk human papillomavirus DNA.

    Science.gov (United States)

    Bartosik, Martin; Durikova, Helena; Vojtesek, Borivoj; Anton, Milan; Jandakova, Eva; Hrstka, Roman

    2016-09-15

    Cervical cancer, being the fourth leading cause of cancer death in women worldwide, predominantly originates from a persistent infection with a high-risk human papillomavirus (HPV). Detection of DNA sequences from these high-risk strains, mostly HPV-16 and HPV-18, represents promising strategy for early screening, which would help to identify women with higher risk of cervical cancer. In developing countries, inadequate screening options lead to disproportionately high mortality rates, making a fast and inexpensive detection schemes highly important. Electrochemical sensors and assays offer an alternative to current methods of detection. We developed an electrochemical-chip based assay, in which target HPV DNA is captured via magnetic bead-modified DNA probes, followed by an antidigoxigenin-peroxidase detection system at screen-printed carbon electrode chips, enabling parallel measurements of eight samples simultaneously. We show sensitive detection in attomoles of HPV DNA, selective discrimination between HPV-16 and HPV-18 and good reproducibility. Most importantly, we show application of the assay into both cancer cell lines and cervical smears from patients. The electrochemical results correlated well with standard methods, making this assay potentially applicable in clinical practice.

  4. Highly sensitive dual mode electrochemical platform for microRNA detection

    Science.gov (United States)

    Jolly, Pawan; Batistuti, Marina R.; Miodek, Anna; Zhurauski, Pavel; Mulato, Marcelo; Lindsay, Mark A.; Estrela, Pedro

    2016-11-01

    MicroRNAs (miRNAs) play crucial regulatory roles in various human diseases including cancer, making them promising biomarkers. However, given the low levels of miRNAs present in blood, their use as cancer biomarkers requires the development of simple and effective analytical methods. Herein, we report the development of a highly sensitive dual mode electrochemical platform for the detection of microRNAs. The platform was developed using peptide nucleic acids as probes on gold electrode surfaces to capture target miRNAs. A simple amplification strategy using gold nanoparticles has been employed exploiting the inherent charges of the nucleic acids. Electrochemical impedance spectroscopy was used to monitor the changes in capacitance upon any binding event, without the need for any redox markers. By using thiolated ferrocene, a complementary detection mode on the same sensor was developed where the increasing peaks of ferrocene were recorded using square wave voltammetry with increasing miRNA concentration. This dual-mode approach allows detection of miRNA with a limit of detection of 0.37 fM and a wide dynamic range from 1 fM to 100 nM along with clear distinction from mismatched target miRNA sequences. The electrochemical platform developed can be easily expanded to other miRNA/DNA detection along with the development of microarray platforms.

  5. Electrochemical biosensor for Mycobacterium tuberculosis DNA detection based on gold nanotubes array electrode platform.

    Science.gov (United States)

    Torati, Sri Ramulu; Reddy, Venu; Yoon, Seok Soo; Kim, CheolGi

    2016-04-15

    The template assisted electrochemical deposition technique was used for the synthesis of gold nanotubes array (AuNTsA). The morphological structure of the synthesized AuNTsA was observed by scanning electron microscopy and found that the individual nanotubes are around 1.5 μm in length with a diameter of 200 nm. Nanotubes are vertically aligned to the Au thick film, which is formed during the synthesis process of nanotubes. The electrochemical performance of the AuNTsA was compared with the bare Au electrode and found that AuNTsA has better electron transfer surface than bare Au electrode which is due to the high surface area. Hence, the AuNTsA was used as an electrode for the fabrication of DNA hybridization biosensor for detection of Mycobacterium Tuberculosis DNA. The DNA hybridization biosensor constructed by AuNTsA electrode was characterized by cyclic voltammetry technique with Fe(CN)6(3-/4-) as an electrochemical redox indicator. The selectivity of the fabricated biosensor was illustrated by hybridization with complementary DNA and non-complementary DNA with probe DNA immobilized AuNTsA electrode using methylene blue as a hybridization indicator. The developed electrochemical DNA biosensor shows good linear range of complementary DNA concentration from 0.01 ng/μL to 100 ng/μL with high detection limit.

  6. Immobilization-free electrochemical DNA detection with anthraquinone-labeled pyrrolidinyl peptide nucleic acid probe.

    Science.gov (United States)

    Kongpeth, Jutatip; Jampasa, Sakda; Chaumpluk, Piyasak; Chailapakul, Orawon; Vilaivan, Tirayut

    2016-01-01

    Electrochemical detection provides a simple, rapid, sensitive and inexpensive method for DNA detection. In traditional electrochemical DNA biosensors, the probe is immobilized onto the electrode. Hybridization with the DNA target causes a change in electrochemical signal, either from the intrinsic signal of the probe/target or through a label or a redox indicator. The major drawback of this approach is the requirement for probe immobilization in a controlled fashion. In this research, we take the advantage of different electrostatic properties between PNA and DNA to develop an immobilization-free approach for highly sequence-specific electrochemical DNA sensing on a screen-printed carbon electrode (SPCE) using a square-wave voltammetric (SWV) technique. Anthraquinone-labeled pyrrolidinyl peptide nucleic acid (AQ-PNA) was employed as a probe together with an SPCE that was modified with a positively-charged polymer (poly quaternized-(dimethylamino-ethyl)methacrylate, PQDMAEMA). The electrostatic attraction between the negatively-charged PNA-DNA duplex and the positively-charged modified SPCE attributes to the higher signal of PNA-DNA duplex than that of the electrostatically neutral PNA probe, resulting in a signal change. The calibration curve of this proposed method exhibited a linear range between 0.35 and 50 nM of DNA target with a limit of detection of 0.13 nM (3SD(blank)/Slope). The sub-nanomolar detection limit together with a small sample volume required (20 μL) allowed detection of DNA. With the high specificity of the pyrrolidinyl PNA probe used, excellent discrimination between complementary and various single-mismatched DNA targets was obtained. An application of this new platform for a sensitive and specific detection of isothermally-amplified shrimp's white spot syndrome virus (WSSV) DNA was successfully demonstrated.

  7. Conservation laws and path-independent integrals in mechanical-diffusion-electrochemical reaction coupling system

    Science.gov (United States)

    Yu, Pengfei; Wang, Hailong; Chen, Jianyong; Shen, Shengping

    2017-07-01

    In this study, the conservation laws οf dissipative mechanical-diffusion-electrochemical reaction system are systematically obtained based on Noether's theorem. According to linear, irreversible thermodynamics, dissipative phenomena can be described by an irreversible force and an irreversible flow. Additionally, the Lagrange function, L and the generalized Hamilton least-action principle are proposed to be used to obtain the conservation integrals. A group of these integrals, including the J-, M-, and L-integrals, can be then obtained using the classical Noether approach for dissipative processes. The relation between the J-integral and the energy release rate is illustrated. The path-independence of the J-integral is then proven. The J-integral, derived based on Noether's theorem, is a line integral, contrary to the propositions of existing published works that describe it both as a line and an area integral. Herein, we prove that the outcomes are identical, and identify the physical meaning of the area integral, a concept that was not explained previously. To show that the J-integral can dominate the distribution of the corresponding field quantities, an example of a partial, stress-diffusion coupling process is disscussed.

  8. Evaluation of an integrated continuous stirred microbial electrochemical reactor: Wastewater treatment, energy recovery and microbial community.

    Science.gov (United States)

    Wang, Haiman; Qu, Youpeng; Li, Da; Zhou, Xiangtong; Feng, Yujie

    2015-11-01

    A continuous stirred microbial electrochemical reactor (CSMER) was developed by integrating anaerobic digestion (AD) and microbial electrochemical system (MES). The system was capable of treating high strength artificial wastewater and simultaneously recovering electric and methane energy. Maximum power density of 583±9, 562±7, 533±10 and 572±6 mW m(-2) were obtained by each cell in a four-independent circuit mode operation at an OLR of 12 kg COD m(-3) d(-1). COD removal and energy recovery efficiency were 87.1% and 32.1%, which were 1.6 and 2.5 times higher than that of a continuous stirred tank reactor (CSTR). Larger amount of Deltaproteobacteria (5.3%) and hydrogenotrophic methanogens (47%) can account for the better performance of CSMER, since syntrophic associations among them provided more degradation pathways compared to the CSTR. Results demonstrate the CSMER holds great promise for efficient wastewater treatment and energy recovery.

  9. Heteronanojunctions with atomic size control using a lab-on-chip electrochemical approach with integrated microfluidics.

    Science.gov (United States)

    Lunca Popa, P; Dalmas, G; Faramarzi, V; Dayen, J F; Majjad, H; Kemp, N T; Doudin, B

    2011-05-27

    A versatile tool for electrochemical fabrication of heteronanojunctions with nanocontacts made of a few atoms and nanogaps of molecular spacing is presented. By integrating microfluidic circuitry in a lab-on-chip approach, we keep control of the electrochemical environment in the vicinity of the nanojunction and add new versatility for exchanging and controlling the junction's medium. Nanocontacts made of various materials by successive local controlled depositions are demonstrated, with electrical properties revealing sizes reaching a few atoms only. Investigations on benchmark molecular electronics material, trapped between electrodes, reveal the possibility to create nanogaps of size matching those of molecules. We illustrate the interest of a microfluidic approach by showing that exposure of a fabricated molecular junction to controlled high solvent flows can be used as a reliability criterion for the presence of molecular entities in a gap.

  10. Bioluminescent bioreporter integrated circuit detection methods

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, Michael L.; Paulus, Michael J.; Sayler, Gary S.; Applegate, Bruce M.; Ripp, Steven A.

    2005-06-14

    Disclosed are monolithic bioelectronic devices comprising a bioreporter and an OASIC. These bioluminescent bioreporter integrated circuit are useful in detecting substances such as pollutants, explosives, and heavy-metals residing in inhospitable areas such as groundwater, industrial process vessels, and battlefields. Also disclosed are methods and apparatus for detection of particular analytes, including ammonia and estrogen compounds.

  11. Integration of control and fault detection

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Stoustrup, J.

    The integrated design of control and fault detection is studied. The result of the analysis is that it is possible to separate the design of the controller and the filter for fault detection in the case where the nominal model can be assumed to be fairly accurate. In the uncertain case, however...

  12. Electrochemical Methods for Human Growth Hormone Doping Detection

    OpenAIRE

    2015-01-01

    Human Growth Hormone (GH) is produced by the anterior pituitary gland and promotes growth of tissue through direct uptake at target tissue sites, or alternatively, by regulating production of insulin-like growth factor-1. The World Anti-Doping Agency considers GH a performance enhancing substance, so the use of GH by athletes is prohibited in most sports. The current immunoassay for GH detection is suboptimal for routine screening of blood samples because of the large resources required for c...

  13. Highly sensitive detection of cancer cells with an electrochemical cytosensor based on boronic acid functional polythiophene.

    Science.gov (United States)

    Dervisevic, Muamer; Senel, Mehmet; Sagir, Tugba; Isik, Sevim

    2017-04-15

    The detection of cancer cells through important molecular recognition target such as sialic acid is significant for the clinical diagnosis and treatment. There are many electrochemical cytosensors developed for cancer cells detection but most of them have complicated fabrication processes which results in poor reproducibility and reliability. In this study, a simple, low-cost, and highly sensitive electrochemical cytosensor was designed based on boronic acid-functionalized polythiophene. In cytosensors fabrication simple single-step procedure was used which includes coating pencil graphite electrode (PGE) by means of electro-polymerization of 3-Thienyl boronic acid and Thiophen. Electrochemical impedance spectroscopy and cyclic voltammetry were used as an analytical methods to optimize and measure analytical performances of PGE/P(TBA0.5Th0.5) based electrode. Cytosensor showed extremely good analytical performances in detection of cancer cells with linear rage of 1×10(1) to 1×10(6) cellsmL(-1) exhibiting low detection limit of 10 cellsmL(-1) and incubation time of 10min. Next to excellent analytical performances, it showed high selectivity towards AGS cancer cells when compared to HEK 293 normal cells and bone marrow mesenchymal stem cells (BM-hMSCs). This method is promising for future applications in early stage cancer diagnosis.

  14. Evaluation of Hydrophilized Graphite Felt for Electrochemical Heavy Metals Detection (Pb2+, Hg2+

    Directory of Open Access Journals (Sweden)

    Laila Bouabdalaoui

    2015-01-01

    Full Text Available Hydrophilized graphite felt has been used, for the first time, for the electrochemical detection of Hg2+ ions both as single metal species and via its simultaneous detection with Pb2+. To do so, square wave voltammetry (SWV method was developed with alginate modified graphite felt as working electrode. The structure of the graphite felt such as its high porosity and specific surface area coupled with its good electrical conductivity allows achieving large peak currents via the SWV method, suggesting that the alginate coating helps to preconcentrate metals at the carbon surface. The as-described electrode has low cost, it is easy to manipulate, and the electrochemical analysis can be performed by simple immersion of the felt in the metal solution.

  15. Highly specific and sensitive electrochemical genotyping via gap ligation reaction and surface hybridization detection.

    Science.gov (United States)

    Huang, Yong; Zhang, Yan-Li; Xu, Xiangmin; Jiang, Jian-Hui; Shen, Guo-Li; Yu, Ru-Qin

    2009-02-25

    This paper developed a novel electrochemical genotyping strategy based on gap ligation reaction with surface hybridization detection. This strategy utilized homogeneous enzymatic reactions to generate molecular beacon-structured allele-specific products that could be cooperatively annealed to capture probes stably immobilized on the surface via disulfide anchors, thus allowing ultrasensitive surface hybridization detection of the allele-specific products through redox tags in close proximity to the electrode. Such a unique biphasic architecture provided a universal methodology for incorporating enzymatic discrimination reactions in electrochemical genotyping with desirable reproducibility, high efficiency and no interferences from interficial steric hindrance. The developed technique was demonstrated to show intrinsic high sensitivity for direct genomic analysis, and excellent specificity with discriminativity of single nucleotide variations.

  16. Nanomaterials-Based Sensing Strategies for Electrochemical Detection of MicroRNAs

    Directory of Open Access Journals (Sweden)

    Ning Xia

    2014-07-01

    Full Text Available MicroRNAs (miRNAs play important functions in post-transcriptional regulation of gene expression. They have been regarded as reliable molecular biomarkers for many diseases including cancer. However, the content of miRNAs in cells can be low down to a few molecules per cell. Thus, highly sensitive analytical methods for miRNAs detection are desired. Recently, electrochemical biosensors have held great promise as devices suitable for point-of-care diagnostics and multiplexed platforms for fast, simple and low-cost nucleic acid analysis. Signal amplification by nanomaterials is one of the most popular strategies for developing ultrasensitive assay methods. This review surveys the latest achievements in the use of nanomaterials to detect miRNAs with a focus on electrochemical techniques.

  17. Polyaniline/Prussian Blue Composite Film Electrochemical Biosensors for Cholesterol Detection

    Institute of Scientific and Technical Information of China (English)

    LI, Jian-Ping(李建平); PENG,Tu-Zhi(彭图治)

    2002-01-01

    An electrochemical biosensor fabricated by immobilization of cholesterol oxidase (ChOx) in a polyaniline (PAN)/prussian blue (PB) conductive layer of glassy carbon electrode has been prepared, based on the detection of hydrogen peroxide produced by ChOx at -0.05 V. The properties of the biosensor were investigated and the measurement conditions for cholesterol were optimized. A linear relationship between electrochemical signal and cholesterol concentration in a range of 1 ×10-6-8 × 10-5 mol/L was observed. It is one of the most sensitive sensors for cholesterol determination, since a low detection limit of 1.8 × 10-7 mol/L was found. Good properties of the biosensor were attributed to high activity of ChOx and effective electro-catalysis of PB modifier in the composite layer on electrode surface.

  18. Polyaniline/Prussian Blue Composite Film Electrochemical Biosensors for Cholesterol Detection

    Institute of Scientific and Technical Information of China (English)

    李建平; 彭图治

    2002-01-01

    An electrochemical biosensor fabricated by immobilization of cholesterol oxidase(ChOx) in a poayaniline (PAN)/prussian blue(PB) conductive layer of glassy carbon electrode has been prepared,based on the detection of hydrogen peroxide produced by ChOx at-0.05v.The properties of the biosensor were investigated and the measurement conditions for cholesterol were optimized.A linear relationship between electrochemical signal and cholesterol concentration in a range of 1×10-6—8×10-5mol/L was observed.It is one of the most sensitive sensors for cholesterol determination,since a low detection limit of 1.8×10-7mol/L was found.Good properties of the biosensor were attributed to high activity of ChOx and effective electro-catalysis of PB modifier in the composite layer on electrode surface.

  19. Electrochemical studies of cystine modified self-assembled monolayer for Escherichia coli detection

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Chandra Mouli; Sumana, Gajjala [Department of Science and Technology Centre on Biomolecular Electronics, Biomedical Instrumentation Section, Materials Physics and Engineering Division, National Physical Laboratory (Council of Scientific and Industrial Research), Dr. K. S. Krishnan Marg, New Delhi 110012 (India); Sood, K.N. [Electron Microscope Section, Division of Material Characterization, National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012 (India); Malhotra, B.D., E-mail: bansi.malhotra@gmail.co [Department of Science and Technology Centre on Biomolecular Electronics, Biomedical Instrumentation Section, Materials Physics and Engineering Division, National Physical Laboratory (Council of Scientific and Industrial Research), Dr. K. S. Krishnan Marg, New Delhi 110012 (India)

    2010-11-30

    An electrochemical DNA biosensor based on cystine modified self-assembled monolayer (cys-SAM) onto gold electrode (AuE) has been fabricated for Escherichia coli (E. coli) detection. This biosensing electrode has been characterized using scanning electron microscopy (SEM), FT-IR spectroscopy, cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under the optimum conditions, this DNA biosensor can be used to detect complementary target DNA concentration in the range of 1 x 10{sup -6} M to 1 x 10{sup -20} M within 60 s of hybridization time at 25 {sup o}C and has been found to be stable for about four months when stored at 4 {sup o}C.

  20. 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.

  1. Microelectromechanical system-based electrochemical seismic sensors with an anode and a cathode integrated on one chip

    Science.gov (United States)

    Deng, T.; Sun, Z.; Li, G.; Chen, J.; Chen, D.; Wang, J.

    2017-02-01

    This paper presents a microelectromechanical system (MEMS)-based electrochemical seismic sensor with an anode and a cathode integrated on a single chip. The proposed approach decreases the number of requested wafers as the sensing unit from seven to two. In addition, no alignment and no bonding among the electrodes are needed, significantly simplifying the fabrication process. The experimental results indicate that the proposed device produced a sensitivity of 5771.7 V (m s-1)-1 at 1.4 Hz and a noise level of  -163 dB (i.e. 7.1 (nm s-1)/Hz1/2) at 1 Hz. Moreover, the proposed device effectively responds to random ground motions, enabling the detection of low-frequency seismic motions caused by earthquake events.

  2. Complexes of carbon nanotubes with oligonucleotides in thin Langmuir-Blodgett films to detect electrochemically hybridization

    Science.gov (United States)

    Egorov, A. S.; Egorova, V. P.; Krylova, H. V.; Lipnevich, I. V.; Orekhovskaya, T. I.; Veligura, A. A.; Govorov, M. I.; Shulitsky, B. G.

    2014-10-01

    Self-assembled complexes consisting of thin multi-walled carbon nanotubes (MWCNTs) and DNA-oligonucleotides which are able to a cooperative binding to complementary oligonucleotides have been investigated. It was establised a high-performance charge transport in nanostructured Langmuir-Blodgett complexes thin MWCNTs/DNA. A method to electrochemically detect DNA hybridization on the self-organized structures has been proposed.

  3. Electrochemical paper-based peptide nucleic acid biosensor for detecting human papillomavirus.

    Science.gov (United States)

    Teengam, Prinjaporn; Siangproh, Weena; Tuantranont, Adisorn; Henry, Charles S; Vilaivan, Tirayut; Chailapakul, Orawon

    2017-02-01

    A novel paper-based electrochemical biosensor was developed using an anthraquinone-labeled pyrrolidinyl peptide nucleic acid (acpcPNA) probe (AQ-PNA) and graphene-polyaniline (G-PANI) modified electrode to detect human papillomavirus (HPV). An inkjet printing technique was employed to prepare the paper-based G-PANI-modified working electrode. The AQ-PNA probe baring a negatively charged amino acid at the N-terminus was immobilized onto the electrode surface through electrostatic attraction. Electrochemical impedance spectroscopy (EIS) was used to verify the AQ-PNA immobilization. The paper-based electrochemical DNA biosensor was used to detect a synthetic 14-base oligonucleotide target with a sequence corresponding to human papillomavirus (HPV) type 16 DNA by measuring the electrochemical signal response of the AQ label using square-wave voltammetry before and after hybridization. It was determined that the current signal significantly decreased after the addition of target DNA. This phenomenon is explained by the rigidity of PNA-DNA duplexes, which obstructs the accessibility of electron transfer from the AQ label to the electrode surface. Under optimal conditions, the detection limit of HPV type 16 DNA was found to be 2.3 nM with a linear range of 10-200 nM. The performance of this biosensor on real DNA samples was tested with the detection of PCR-amplified DNA samples from the SiHa cell line. The new method employs an inexpensive and disposable device, which easily incinerated after use and is promising for the screening and monitoring of the amount of HPV-DNA type 16 to identify the primary stages of cervical cancer.

  4. Development of an electrochemically integrated SR-GIXRD flow cell to study FeCO3 formation kinetics

    Science.gov (United States)

    Burkle, D.; De Motte, R.; Taleb, W.; Kleppe, A.; Comyn, T.; Vargas, S. M.; Neville, A.; Barker, R.

    2016-10-01

    An electrochemically integrated Synchrotron Radiation-Grazing Incidence X-Ray Diffraction (SR-GIXRD) flow cell for studying corrosion product formation on carbon steel in carbon dioxide (CO2)-containing brines typical of oil and gas production has been developed. The system is capable of generating flow velocities of up to 2 m/s at temperatures in excess of 80 °C during SR-GIXRD measurements of the steel surface, enabling flow to be maintained over the course of the experiment while diffraction patterns are being collected. The design of the flow cell is presented, along with electrochemical and diffraction pattern transients collected from an initial experiment which examined the precipitation of FeCO3 onto X65 carbon steel in a CO2-saturated 3.5 wt. % NaCl brine at 80 °C and 0.1 m/s. The flow cell is used to follow the nucleation and growth kinetics of FeCO3 using SR-GIXRD linked to the simultaneous electrochemical response of the steel surface which were collected in the form of linear polarisation resistance measurements to decipher in situ corrosion rates. The results show that FeCO3 nucleation could be detected consistently and well before its inhibitive effect on the general corrosion rate of the system. In situ measurements are compared with ex situ scanning electron microscopy (SEM) observations showing the development of an FeCO3 layer on the corroding steel surface over time confirming the in situ interpretations. The results presented demonstrate that under the specific conditions evaluated, FeCO3 was the only crystalline phase to form in the system, with no crystalline precursors being apparent. The numerous capabilities of the flow cell are highlighted and presented in this paper.

  5. 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.

  6. Label-free electrochemical impedance detection of kinase and phosphatase activities using carbon nanofiber nanoelectrode arrays

    Science.gov (United States)

    Li, Yifen; Syed, Lateef; Liu, Jianwei; Hua, Duy H.; Li, Jun

    2012-01-01

    We demonstrate the feasibility of a label-free electrochemical method to detect the kinetics of phosphorylation and dephosphorylation of surface-attached peptides catalyzed by kinase and phosphatase, respectively. The peptides with a sequence specific to c-Src tyrosine kinase and protein tyrosine phosphatase 1B (PTP1B) were first validated with ELISA-based protein tyrosine kinase assay and then functionalized on vertically aligned carbon nanofiber (VACNF) nanoelectrode arrays (NEAs). Real-time electrochemical impedance spectroscopy (REIS) measurements showed reversible impedance changes upon the addition of c-Src kinase and PTP1B phosphatase. Only a small and unreliable impedance variation was observed during the peptide phosphorylation, but a large and fast impedance decrease was observed during the peptide dephosphorylation at different PTP1B concentrations. The REIS data of dephosphorylation displayed a well-defined exponential decay following the Michaelis-Menten heterogeneous enzymatic model with a specific constant, kcat/Km, of (2.1 ± 0.1) × 107 M−1 s−1. Consistent values of the specific constant was measured at PTP1B concentration varying from 1.2 to 2.4 nM with the corresponding electrochemical signal decay constant varying from 38.5 to 19.1 s. This electrochemical method can be potentially used as a label-free method for profiling enzyme activities in fast reactions. PMID:22935373

  7. PMMA-based capillary electrophoresis electrochemical detection microchip fabrication

    Science.gov (United States)

    Horng, Ray-Hua; Han, Pin; Chen, Hung-Yu; Lin, Kuan-Wen; Tsai, Tung-Mung; Zen, Jyh-Myng

    2005-01-01

    In this paper, a 50 µm (depth) × 50 µm (width) microfluidic channel is made on a poly(methyl methacrylate) (PMMA) substrate using thick photoresist. Openings were drilled for buffer reservoirs on an additional piece of PMMA. A final PMMA/patterned photoresist/PMMA sandwich configuration was completed using a bonding process. The thick photoresist was used as the adhesion layer and also as the microfluidic system. Using screen-printed technology for carbon and silver electrode fabrication, the microchip electrophoretic device functions were demonstrated. Successful detection of uric acid and L-ascorbic acid (the main components in human urine) validates the functionality of the proposed system. Successful ascorbic and uric acid separation in a sample from a urine donor who had consumed 500 mg of vitamins verified the proposed biochip.

  8. Label-free and highly sensitive electrochemical detection of E. coli based on rolling circle amplifications coupled peroxidase-mimicking DNAzyme amplification.

    Science.gov (United States)

    Guo, Yuna; Wang, Yu; Liu, Su; Yu, Jinghua; Wang, Hongzhi; Wang, Yalin; Huang, Jiadong

    2016-01-15

    In this work, a simple, label-free, low cost electrochemical biosensor for highly sensitive and selective detection of Escherichia coli has been developed on the basis of rolling circle amplification (RCA) coupled peroxidase-mimicking DNAzyme amplification. A aptamer-primer probe (APP) containing anti-E. coli aptamer and a primer sequence complementary to a circular probe, which includes two G-quadruplex units, is used for recognizing target and triggering RCA-based polymerase elongation. Due to RCA coupled DNAzyme amplification strategy, the presence of target E. coli leads to the formation of numerous G-quadruplex oligomers on electrode, which folds into G-quadruplex/hemin complexs with the help of K(+) and hemin, thus generating extremely strong catalytic activity toward H2O2 and giving a remarkably strong electrochemical response. As far as we know, this work is the first time that RCA coupled peroxidase-mimicking DNAzyme amplification technique have been integrated into electrochemical assay for detecting pathogenic bacteria. Under optimal conditions, the proposed biosensor exhibits ultrahigh sensitivity toward E. coli with detection limits of 8cfumL(-1) and a detection range of 5 orders of magnitude. Besides, our biosensor also shows high selectivity toward target E. coli and has the advantages in its rapidness, low cost, simplified operations without the need of electrochemical labeling steps and additional labile reagents. Hence, the RCA coupled peroxidase-mimicking DNAzyme amplification-based electrochemical method might create a useful and practical platform for detecting E. coli and related food safety analysis and clinical diagnosis. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. An electrochemical DNA biosensor based on Oracet Blue as a label for detection of Helicobacter pylori.

    Science.gov (United States)

    Hajihosseini, Saeedeh; Nasirizadeh, Navid; Hejazi, Mohammad Saeid; Yaghmaei, Parichereh

    2016-10-01

    An innovative method of a DNA electrochemical biosensor based on Oracet Blue (OB) as an electroactive label and gold electrode (AuE) for detection of Helicobacter pylori, was offered. A single-stranded DNA probe with a thiol modification was covalently immobilized on the surface of the AuE by forming an Au-S bond. Differential pulse voltammetry (DPV) was used to monitor DNA hybridization by measuring the electrochemical signals of reduction of the OB binding to double-stranded DNA (ds-DNA). Our results showed that OB-based DNA biosensor has a decent potential for detection of single-base mismatch in target DNA. Selectivity of the proposed DNA biosensor was further confirmed in the presence of non-complementary and complementary DNA strands. Under optimum conditions, the electrochemical signal had a linear relationship with the concentration of the target DNA ranging from 0.3nmolL(-1) to 240.0nmolL(-1), and the detection limit was 0.17nmolL(-1), whit a promising reproducibility and repeatability.

  10. Detection of Interferon gamma using graphene and aptamer based FET-like electrochemical biosensor.

    Science.gov (United States)

    Farid, Sidra; Meshik, Xenia; Choi, Min; Mukherjee, Souvik; Lan, Yi; Parikh, Devanshi; Poduri, Shripriya; Baterdene, Undarmaa; Huang, Ching-En; Wang, Yung Yu; Burke, Peter; Dutta, Mitra; Stroscio, Michael A

    2015-09-15

    One of the primary goals in the scientific community is the specific detection of proteins for the medical diagnostics and biomedical applications. Interferon-gamma (IFN-γ) is associated with the tuberculosis susceptibility, which is one of the major health problems globally. We have therefore developed a DNA aptamer-based electrochemical biosensor that is used for the detection of IFN-γ with high selectivity and sensitivity. A graphene monolayer-based FET-like structure is incorporated on a PDMS substrate with the IFN-γ aptamer attached to graphene. Addition of target molecule induces a change in the charge distribution in the electrolyte, resulting in increase in electron transfer efficiency that was actively sensed by monitoring the change in current from the device. Change in current appears to be highly sensitive to the IFN-γ concentrations ranging from nanomolar (nM) to micromolar (μM) range. The detection limit of our IFN-γ electrochemical biosensor is found to be 83 pM. Immobilization of aptamer on graphene surface is verified using unique structural approach by Atomic Force Microscopy. Such simple and sensitive electrochemical biosensor has potential applications in infectious disease monitoring, immunology and cancer research in the future.

  11. Electrochemical biosensors based on nanofibres for cardiac biomarker detection: A comprehensive review.

    Science.gov (United States)

    Rezaei, Babak; Ghani, Mozhdeh; Shoushtari, Ahmad Mousavi; Rabiee, Mohammad

    2016-04-15

    The vital importance of early and accurate diagnosis of cardiovascular diseases (CVDs) to prevent the irreversible damage or even death of patients has driven the development of biosensor devices for detection and quantification of cardiac biomarkers. Electrochemical biosensors offer rapid sensing, low cost, portability and ease of use. Over the past few years, nanotechnology has contributed to a tremendous improvement in the sensitivity of biosensors. In this review, the authors summarise the state-of-the-art of the application of one particular type of nanostructured material, i.e. nanofibres, for use in electrochemical biosensors for the ultrasensitive detection of cardiac biomarkers. A new way of classifying the nanofibre-based electrochemical biosensors according to the electrical conductance and the type of nanofibres is presented. Some key data from each article reviewed are highlighted, including the mechanism of detection, experimental conditions and the response range of the biosensor. The primary aim of this review is to emphasise the prospects for nanofibres for the future development of biosensors in diagnosis of CVDs as well as considering how to improve their characteristics for application in medicine.

  12. Development of an electrochemical immunoassay for detection of gatifloxacin in swine urine

    Institute of Scientific and Technical Information of China (English)

    Jian YI; Meng MENG; Zhong-qiu LIU; Jin-fang ZHI; Yuan-yang ZHANG; Jing XU; Ya-bin WANG; Jin-ting LIU; Ri-mo XI

    2012-01-01

    To detect gatifloxacin (GAT) residue in swine urine,an electrochemical immunoassay was established.An indirect competitive immunoassay was developed,in which the coating antigen is immobilized in an enzyme-linked immunosorbent assay (ELISA) plate and GAT residue from the sample competes with the limited binding sites in added anti-GAT antibody.Horseradish peroxidase (HRP) conjugated to goat anti-rabbit IgG was used as the enzymatic label.A carbon fiber working electrode was constructed and current signals were detected by using hydrogen peroxide as a substrate and hydroquinone as an electrochemical mediator.The electrochemical immunoassay was evaluated by analysis of GAT in buffer or swine urine and an average value of half inhibition concentration (IC50) of 8.9 ng/ml was obtained.Excellent specificity of the antibody was achieved with little cross-reaction with Iomefloxacin (3.0%),ciprofloxacin (3.0%),and ofloxacin (1.9%) among commonly used (fiuoro)quinolones.In conclusion,the immunoassay system developed in this research can be used as a rapid,powerful and on-site analytical tool to detect GAT residue in foods and food products.

  13. Plasma-Modified, Epitaxial Fabricated Graphene on SiC for the Electrochemical Detection of TNT

    Directory of Open Access Journals (Sweden)

    Scott A. Trammell

    2016-08-01

    Full Text Available Using square wave voltammetry, we show an increase in the electrochemical detection of trinitrotoluene (TNT with a working electrode constructed from plasma modified graphene on a SiC surface vs. unmodified graphene. The graphene surface was chemically modified using electron beam generated plasmas produced in oxygen or nitrogen containing backgrounds to introduce oxygen or nitrogen moieties. The use of this chemical modification route enabled enhancement of the electrochemical signal for TNT, with the oxygen treatment showing a more pronounced detection than the nitrogen treatment. For graphene modified with oxygen, the electrochemical response to TNT can be fit to a two-site Langmuir isotherm suggesting different sites on the graphene surface with different affinities for TNT. We estimate a limit of detection for TNT equal to 20 ppb based on the analytical standard S/N ratio of 3. In addition, this approach to sensor fabrication is inherently a high-throughput, high-volume process amenable to industrial applications. High quality epitaxial graphene is easily grown over large area SiC substrates, while plasma processing is a rapid approach to large area substrate processing. This combination facilitates low cost, mass production of sensors.

  14. Development of a lab-on-chip electrochemical immunosensor for detection of Polycyclic Aromatic Hydrocarbons (PAH) in environmental water

    Science.gov (United States)

    Felemban, Shifa; Vazquez, Patricia; Dehnert, Jan; Goridko, Vadim; Tijero, Maria; Moore, Eric

    2017-06-01

    The work described in this manuscript focuses on how the integration of immunoassay techniques in combination with electrochemical detection can provide a portable and very accurate solution for detection of water pollutants that are detrimental for human health. In particular, we focus our work on the quantification of polycyclic aromatic hydrocarbons (PAHs) in polluted water. Our integrative approach facilitates a real-time detection of this family of organic compounds, by reducing the time of analysis to less than one hour. Additionally, the use of a lab-on-a-chip platform delivers a portable solution that could be used in situ. Optimization of a displacement assay that investigates the presence and concentration of Benzo[a]pyrene in water, allows with the miniaturization of the standard ELISA format into a highly accurate system that provides fast results. The limits of detection obtained are comparable to those of available state-of-the art tools, and achieve the values set by European Drinking Water Directive, 0.10ng/l, as the limit for PAHs in drinking water.

  15. Selective detection of endotoxin using an impedance aptasensor with electrochemically deposited gold nanoparticles.

    Science.gov (United States)

    Su, Wenqiong; Kim, Sung-Eun; Cho, MiSuk; Nam, Jae-Do; Choe, Woo-Seok; Lee, Youngkwan

    2013-01-01

    Using a single-stranded DNA (ssDNA) aptamer exhibiting high binding affinity (Kd = 12 nM) to endotoxin as a probe, an impedance sensor where aptamer-conjugated gold nanoparticles (AuNPs) were electrochemically deposited on a gold electrode was fabricated and its performance in regard to endotoxin detection assessed. AuNPs have been employed widely as biosensors because of their unique physical and chemical properties. In order to maximize the performance of the impedance aptasensor on endotoxin detection, some critical factors affecting aptamer conjugation to AuNPs and target recognition ability (i.e. concentrations of aptamer coupled with AuNPs, pH, ion strength and cation effect at the time of aptamer-endotoxin interaction) were optimized. Electrochemical impendence spectroscopy, cyclic voltametry, atomic force microscope, scanning electron microscope and quartz crystal microbalance were employed to characterize all the modification/detection procedures during the sensor fabrication. The developed aptasensor showed a broad linear dynamic detection range (0.01-10.24 ng/ml) with a very low detection limit for endotoxin (0.005 ng/ml), despite the presence of several biomolecules (e.g. plasmid DNA, RNA, serum albumin, Glc and sucrose) known to interfere with other endotoxin assays. The demonstrated aptasensor required a detection time of only 10 min, providing a simple and fast analytical method to specifically detect endotoxin from complex biological liqors.

  16. Electrochemical detection of leukemia oncogenes using enzyme-loaded carbon nanotube labels

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ai Cheng; Du, Dan; Chen, Baowei; Heng, Chew-Kiat; Lim, Tit-Meng; Lin, Yuehe

    2014-09-07

    Here we describe an ultrasensitive electrochemical nucleic acids assay amplified by carbon nanotubes (CNTs)-based labels for the detection of human acute lymphocytic leukemia (ALL) related p185 BCR-ABL fusion transcript. The carboxylated CNTs were functionalized with horseradish peroxidase (HRP) molecules and target-specific detection probes (DP) via diimide-activated amidation, and used to label and amplify target hybridization signal. The activity of captured HRP was monitored by square-wave voltammetry measuring the electroactive enzymatic product in the presence of 2-aminophenol and hydrogen peroxide substrate solution. The effect of DP and HRP loading of the CNT-based labels on its signal-to-noise ratio of electrochemical detection was studied systematically for the first time. Under optimized conditions, the signal-amplified assay achieved a detection limit of 83 fM targets oligonuecleotides and a 4-order wide dynamic range of target concentration. The resulting assay allowed a robust discrimination between the perfect match and a three-base mismatch sequence. When subjected to full-length (491 bp) DNA oncogene, the approach demonstrated a detection limit of approximately 33 pg of the target gene. The high sensitivity and specificity of assay enabled PCR-free detection of target transcripts in as little as 65 ng of mRNA extracted from positive ALL cell lines SUP-B15, in comparison to those obtained from negative cell lines HL-60. The approach holds promise for simple, low cost and ultrasensitive electrochemical nucleic acids detection in portable devices, point-of-care and early disease diagnostic applications.

  17. Methylene blue not ferrocene: Optimal reporters for electrochemical detection of protease activity.

    Science.gov (United States)

    González-Fernández, Eva; Avlonitis, Nicolaos; Murray, Alan F; Mount, Andrew R; Bradley, Mark

    2016-10-15

    Electrochemical peptide-based biosensors are attracting significant attention for the detection and analysis of proteins. Here we report the optimisation and evaluation of an electrochemical biosensor for the detection of protease activity using self-assembled monolayers (SAMs) on gold surfaces, using trypsin as a model protease. The principle of detection was the specific proteolytic cleavage of redox-tagged peptides by trypsin, which causes the release of the redox reporter, resulting in a decrease of the peak current as measured by square wave voltammetry. A systematic enhancement of detection was achieved through optimisation of the properties of the redox-tagged peptide; this included for the first time a side-by-side study of the applicability of two of the most commonly applied redox reporters used for developing electrochemical biosensors, ferrocene and methylene blue, along with the effect of changing both the nature of the spacer and the composition of the SAM. Methylene blue-tagged peptides combined with a polyethylene-glycol (PEG) based spacer were shown to be the best platform for trypsin detection, leading to the highest fidelity signals (characterised by the highest sensitivity (signal gain) and a much more stable background than that registered when using ferrocene as a reporter). A ternary SAM (T-SAM) configuration, which included a PEG-based dithiol, minimised the non-specific adsorption of other proteins and was sensitive towards trypsin in the clinically relevant range, with a Limit of Detection (LoD) of 250pM. Kinetic analysis of the electrochemical response with time showed a good fit to a Michaelis-Menten surface cleavage model, enabling the extraction of values for kcat and KM. Fitting to this model enabled quantitative determination of the solution concentration of trypsin across the entire measurement range. Studies using an enzyme inhibitor and a range of real world possible interferents demonstrated a selective response to trypsin

  18. New Hydrodynamic Electrochemical Arrangement for Cadmium Ions Detection Using Thick-Film Chemical Sensor Electrodes

    Directory of Open Access Journals (Sweden)

    Rene Kizek

    2006-11-01

    Full Text Available Miniaturization and integration of chemical devices into modules that aredimensionally comparable with electronic chips (Lab on Chip is nowadays developingworldwide. The aim of our work was to suggest and optimize the best conditions forfabrication of TFT sensor due to its sensitivity and low experimental deviations. Newelectrochemical analytical device was developed to ensure certain known mass transport toelectrodes, which is the most limiting process that influencing the response quality of thesensor. The device consists from rotating conic vessel for measured sample and stick-inthick-film sensor. The sensors responses were tested under trace analysis of cadmium.Measurements were done also with the others electrochemical arrangements to comparewith the new one. The sensor output current response dependence on the liquid velocity andgeometrical arrangement within using standard electrochemical couple of potassiumferrocyanide-ferricyanide is presented. We found out that the new device with controlledflow of electrolyte to sensor worked properly and gave satisfactory results.

  19. A novel electrochemical immunosensor based on magnetosomes for detection of staphylococcal enterotoxin B in milk.

    Science.gov (United States)

    Wu, Longyun; Gao, Bo; Zhang, Fang; Sun, Xiulan; Zhang, Yinzhi; Li, Zaijun

    2013-03-15

    In this paper, a novel electrochemical immunosensor to detect staphylococcal enterotoxin B based on bio-magnetosomes, polyaniline nano-gold composite and 1,2-dimethyl-3-butylimidazolium hexafluorophosphate ionic liquid, was developed, and found to exhibit high sensitivity and stability. The specific antibody to staphylococcal enterotoxin B conjugated with the magnetosomes showed rapid immunoreactions and good dispersion, which contributed to the formation of a nanostructurally smooth and dense film on the surface of a gold electrode. Polyaniline nano-gold composite and 1,2-dimethyl-3-butylimidazolium hexafluorophosphate ionic liquid were used to modify the electrode as mediators to improve the electron transfer and offer an excellent biocompatible microenvironment for the antibody to retain its activity to enhance the response of the electrochemical sensor. Under optimal conditions, the developed immunosensor showed a good linear response in the range from 0.05 to 5 ng/mL (R(2)=0.9957) with a detection limit as low as 0.017 ng/mL, compared with the one without magnetosomes (0.05-5 ng/mL, 0.033 ng/mL), this developed immunosensor showed a wider response range and a reduced detection limit. And a good specificity with little adsorption to staphylococcal enterotoxin A, C and Na(+), K(+), Ca(2+) was obtained. Moreover, the immunosensor exhibited a good long-time stability at 4 °C reaching up to 60 days, which showed a relatively long working life. Meanwhile the immunosensor could be regenerated four times using NaOH elution. The sensor also displayed a good repeatability with a relative standard deviation of 5.02% for staphylococcal enterotoxin B detection (1 ng/mL, n=9). Furthermore, high recoveries in milk samples from 81% to 118% were achieved and successfully applied to milk sample detection. The obtained results demonstrate that the developed electrochemical immunosensor is a promising tool for the detection of staphylococcal enterotoxin B in food.

  20. Measurement of oxidized and methylated DNA bases by HPLC with electrochemical detection.

    Science.gov (United States)

    Kaur, H; Halliwell, B

    1996-08-15

    Oxidative DNA damage is thought to be an important contributor to cancer development and to be affected by dietary constituents, so its accurate measurement is important. DNA methylation is recognized as an important mechanism affecting gene expression. In the present paper we describe an HPLC-with-electrochemical-detection procedure that allows rapid and sensitive measurement of four oxidized (2,6-diamino-4-hydroxy-5-formamidopyrimidine, 5-hydroxyuracil, 8-hydroxyguanine, 8-hydroxyadenine) and three methylated (7-methylguanine, 1-methylguanine, O6-methylguanine) bases in acid hydrolysates of DNA. Guanine was also detected, but was clearly separated from the other bases.

  1. Overview of Electrochemical DNA Biosensors: New Approaches to Detect the Expression of Life

    Directory of Open Access Journals (Sweden)

    Todd West

    2009-04-01

    Full Text Available DNA microarrays are an important tool with a variety of applications in gene expression studies, genotyping, pharmacogenomics, pathogen classification, drug discovery, sequencing and molecular diagnostics. They are having a strong impact in medical diagnostics for cancer, toxicology and infectious disease applications. A series of papers have been published describing DNA biochips as alternative to conventional microarray platforms to facilitate and ameliorate the signal readout. In this review, we will consider the different methods proposed for biochip construction, focusing on electrochemical detection of DNA. We also introduce a novel single-stranded DNA platform performing high-throughput SNP detection and gene expression profiling.

  2. Detection of Nitroaromatic Explosives Using an Electrical- Electrochemical and Optical Hybrid Sensor

    Science.gov (United States)

    Diaz Aguilar, Alvaro

    In today's world there is a great need for sensing methods as tools to provide critical information to solve today's problems in security applications. Real time detection of trace chemicals, such as explosives, in a complex environment containing various interferents using a portable device that can be reliably deployed in a field has been a difficult challenge. A hybrid nanosensor based on the electrochemical reduction of trinitrotoluene (TNT) and the interaction of the reduction products with conducting polymer nanojunctions in an ionic liquid was fabricated. The sensor simultaneously measures the electrochemical current from the reduction of TNT and the conductance change of the polymer nanojunction caused from the reduction product. The hybrid detection mechanism, together with the unique selective preconcentration capability of the ionic liquid, provides a selective, fast, and sensitive detection of TNT. The sensor, in its current form, is capable of detecting parts per trillion level TNT in the presence of various interferents within a few minutes. A novel hybrid electrochemical-colorimetric (EC-C) sensing platform was also designed and fabricated to meet these challenges. The hybrid sensor is based on electrochemical reactions of trace explosives, colorimetric detection of the reaction products, and unique properties of the explosives in an ionic liquid (IL). This approach affords not only increased sensitivity but also selectivity as evident from the demonstrated null rate of false positives and low detection limits. Using an inexpensive webcam a detection limit of part per billion in volume (ppbV) has been achieved and demonstrated selective detection of explosives in the presence of common interferences (perfumes, mouth wash, cleaners, petroleum products, etc.). The works presented in this dissertation, were published in the Journal of the American Chemical Society (JACS, 2009) and Nano Letters (2010), won first place in the National Defense Research

  3. Nanomaterial based electrochemical sensors for in vitro detection of small molecule metabolites.

    Science.gov (United States)

    Xiao, Fei; Wang, Lu; Duan, Hongwei

    2016-01-01

    Small molecule metabolites secreted by pathological processes can act as molecular biomarkers for clinical diagnosis. In vitro detection of the metabolites such as glucose and reactive oxygen species is of great significance for precise screening, monitoring and prognosis of metabolic disorders and relevant diseases such as cancer, and has been under intense research and development in clinical chemistry and molecular diagnostics. In this review, we summarize recent developments in nanomaterial based electrochemical (bio)sensors for in vitro detection of glucose and reactive oxygen species and the progress in utilizing lightweight and flexible electrodes and micro/nanoscale electrodes for flexible and miniaturized sensors. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Direct electrochemical sensor for label-free DNA detection based on zero current potentiometry.

    Science.gov (United States)

    Wu, Nai-ying; Gao, Wei; He, Xu-lun; Chang, Zhu; Xu, Mao-tian

    2013-01-15

    A direct electrochemical DNA biosensor based on zero current potentiometry was fabricated by immobilization of ssDNA onto gold nanoparticles (AuNPs) coated pencil graphite electrode (PGE). One ssDNA/AuNPs/PGE was connected in series between clips of working and counter electrodes of a potentiostat, and then immersed into the solution together with a reference electrode, establishing a novel DNA biosensor for specific DNA detection. The variation of zero current potential difference (ΔE(zcp)) before and after hybridization of the self-assembled probe DNA with the target DNA was used as a signal to characterize and quantify the target DNA sequence. The whole DNA biosensor fabrication process was characterized by cyclic voltammetry and electrochemical impedance spectroscopy with the use of ferricyanide as an electrochemical redox indicator. Under the optimized conditions, ΔE(zcp) was linear with the concentrations of the complementary target DNA in the range from 10nM to 1μM, with a detection limit of 6.9nM. The DNA biosensor showed a good reproducibility and selectivity. Prepared DNA biosensor is facile and sensitive, and it eliminates the need of using exogenous reagents to monitor the oligonucleotides hybridization.

  5. Sensitive Electrochemical Detection of Dopamine With a Nitrogen-doped Graphene Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Wencheng Wang

    2016-09-01

    Full Text Available In this paper nitrogen-doped graphene (NG nanosheets were used as the modifier on the surface of glassy carbon electrode (GCE. The modified electrode (NG/GCE was further applied to the sensitive detection of dopamine (DA by voltammetric method. Due to the unique properties of NG such as large surface area and excellent electrocatalytic activity, electrochemical response of DA was greatly enhanced on NG/GCE with a pair of well-defined redox peaks appeared on cyclic voltammogram. Electrochemical behaviors of DA on NG/GCE were carefully investigated with the electrochemical parameters calculated. Under the selected conditions the oxidation peak currents of DA had a good linear relationship with its concentration in the range from 8.0×10–7 mol L–1 to 8.0×10–4 mol L–1 with a detection limit of 2.55×10–7 mol L–1 (3σ. The proposed method was further applied to the DA injection samples determination with satisfactory results. This work is licensed under a Creative Commons Attribution 4.0 International License.

  6. Label-free detection of C-reactive protein using an electrochemical DNA immunoassay

    Directory of Open Access Journals (Sweden)

    Temsiri Songjaroen

    2016-05-01

    Full Text Available A label-free electrochemical immunoassay that combines DNA-directed immobilization (DDI with electrochemical impedance spectroscopy (EIS on microwire sensors is reported for the detection of C-reactive protein (CRP. CRP is an acute-phase protein that is strongly correlated with systemic inflammation. Since inflammation plays a role in pathogenesis of cardiovascular diseases, CRP can be used to predict the likelihood of coronary events. To demonstrate the new chemistry, 25-μm Au electrodes were modified with single strand DNA (ssDNA and exposed to a solution containing complementary ssDNA conjugated to monoclonal anti-CRP. The charge-transfer resistance of the [Fe(CN6]3−/4− redox couple was used to determine the CRP concentration after binding. A stepwise increase in the charge transfer resistance was observed using EIS for each modification step, ssDNA, ssDNA-anti-CRP hybridization and the final CRP capture. Cyclic voltammetry (CV was used to verify the EIS results, and showed an increase in peak potential splitting in a similar stepwise manner for each modification step. Finally, fluorescence microscopy was used to confirm the DNA hybridization and CRP binding. Standard addition of CRP revealed that EIS could be used to detect CRP at clinically relevant levels in serum samples. This new form of electrochemical DNA immunoassay (eDI has significant potential as a simple, label-free sensor for proteins in microfluidic devices.

  7. Glycated hemoglobin detection with electrochemical sensing amplified by gold nanoparticles embedded N-doped graphene nanosheet.

    Science.gov (United States)

    Jain, Utkarsh; Chauhan, Nidhi

    2017-03-15

    In the diabetic patients the level of glucose must be determined without any short term fluctuations. The level of Glycated hemoglobin (HbA1c) is accordingly examined for checking diabetes mellitus. HbA1c is considered one of the primarily factor to discern the concentration of average plasma glucose over a long-drawn-out period. In our work, we describe a construction of biosensor which is based on fructosyl amino-acid oxidase (FAO) immobilized nitrogen-doped graphene/gold nanoparticles (AuNPs)/fluorine doped tin oxide (FTO) glass electrode. This constructed biosensor exhibits a wide linear range of 0.3 to 2000μM in response to HbA1c at +0.2V. Consequently, the detection limit of 0.2μM and good stability (4 months) were achieved. The electrocatalytic activity of this sensor was good as a result of synergistic effect of graphene and AuNPs (2D and 0D nanomaterials). The charge transfer resistance was decreased which was observed by electrochemical impedance spectroscopy (EIS) study. The graphene/AuNPs composites film reveals a distinguished electrochemical response to fructosyl valine (FV) which demonstrates a promising application for electrochemical detection of HbA1c in human blood samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. A Zinc Oxide Nanoflower-Based Electrochemical Sensor for Trace Detection of Sunset Yellow

    Science.gov (United States)

    Ya, Yu; Jiang, Cuiwen; Li, Tao; Liao, Jie; Fan, Yegeng; Wei, Yuning; Yan, Feiyan; Xie, Liping

    2017-01-01

    Zinc oxide nanoflower (ZnONF) was synthesized by a simple process and was used to construct a highly sensitive electrochemical sensor for the detection of sunset yellow (SY). Due to the large surface area and high accumulation efficiency of ZnONF, the ZnONF-modified carbon paste electrode (ZnONF/CPE) showed a strong enhancement effect on the electrochemical oxidation of SY. The electrochemical behaviors of SY were investigated using voltammetry with the ZnONF-based sensor. The optimized parameters included the amount of ZnONF, the accumulation time, and the pH value. Under optimal conditions, the oxidation peak current was linearly proportional to SY concentration in the range of 0.50–10 μg/L and 10–70 μg/L, while the detection limit was 0.10 μg/L (signal-to-noise ratio = 3). The proposed method was used to determine the amount of SY in soft drinks with recoveries of 97.5%–103%, and the results were in good agreement with the results obtained by high-performance liquid chromatography. PMID:28282900

  9. Rapid and simple electrochemical detection of morphine on graphene-palladium-hybrid-modified glassy carbon electrode.

    Science.gov (United States)

    Atta, Nada F; Hassan, Hagar K; Galal, Ahmed

    2014-11-01

    A hybrid of reduced graphene oxide-palladium (RGO-Pd) nano- to submicron-scale particles was simultaneously chemically prepared using microwave irradiation. The electrochemical investigation of the resulting hybrid was achieved using cyclic voltammetry and differential pulse voltammetry. RGO-Pd had a higher current response than unmodified RGO toward the oxidation of morphine. Several factors that can affect the electrochemical response were studied, including accumulation time and potential, Pd loading, scan rate, and pH of electrolyte. At the optimum conditions, the concentration of morphine was determined using differential pulse voltammetry in a linear range from 0.34 to 12 μmol L(-1) and from 14 to 100 μmol L(-1), with detection limits of 12.95 nmol L(-1) for the first range. The electrode had high sensitivity toward morphine oxidation in the presence of dopamine (DA) and of the interference compounds ascorbic acid (AA) and uric acid (UA). Electrochemical determination of morphine in a spiked urine sample was performed, and a low detection limit was obtained. Validation conditions including reproducibility, sensitivity, and recovery were evaluated successfully in the determination of morphine in diluted human urine.

  10. Solid-state probe based electrochemical aptasensor for cocaine: a potentially convenient, sensitive, repeatable, and integrated sensing platform for drugs.

    Science.gov (United States)

    Du, Yan; Chen, Chaogui; Yin, Jianyuan; Li, Bingling; Zhou, Ming; Dong, Shaojun; Wang, Erkang

    2010-02-15

    Aptamers, which are artificial oligonucleotides selected in vitro, have been employed to design novel biosensors (i.e., aptasensors). In this work, we first constructed a label-free electrochemical aptasensor introducing a probe immobilization technique by the use of a layer-by-layer (LBL) self-assembled multilayer with ferrocene-appended poly(ethyleneimine) (Fc-PEI) on an indium tin oxide (ITO) array electrode for detection of cocaine. The Fc-PEI and gold nanoparticles (AuNPs) were LBL assembled on the electrode surface via electrostatic interaction. Then, cocaine aptamer fragments, SH-C2, were covalently labeled onto the outermost AuNP layer. When the target cocaine and cocaine aptamer C1 were present simultaneously, the SH-C2 layer hybridized partly with C1 to bind the cocaine, which led to a decreased differential pulse voltammetry (DPV) signal of Fc-PEI. This DPV signal change could be used to sensitively detect cocaine with the lowest detectable concentration down to 0.1 microM and the detection range up to 38.8 microM, which falls in the the expected range for medical use of detecting drug abuse involving cocaine. Meanwhile, the sensor was specific to cocaine in complex biologic fluids such as human plasma, human saliva, etc. The sensing strategy had general applicability, and the detection of thrombin could also be realized, displayed a low detection limit, and exhibited worthiness to other analytes. The aptasensor based on the array electrode held promising potential for integration of the sensing ability in multianalysis for simultaneous detection.

  11. Electrochemical detection of carbidopa using a ferrocene-modified carbon nanotube paste electrode

    Directory of Open Access Journals (Sweden)

    FATEMEH KARIMI

    2009-12-01

    Full Text Available A chemically modified carbon paste electrode (MCPE containing ferrocene (FC and carbon nanotubes (CNT was constructed. The electrochemical behavior and stability of the MCPE were investigated by cyclic voltammetry. The electrocatalytic activity of the MCPE was investigated and it showed good characteristics for the oxidation of carbidopa (CD in phosphate buffer solution (PBS. A linear concentration range of 5 to 600 μM CD, with a detection limit of 3.6±0.17 μM CD, was obtained. The diffusion coefficient of CD and the transfer coefficient ( were also determined. The MCPE showed good reproducibility, remarkable long-term stability and especially good surface renewability by simple mechanical polishing. The results showed that this electrode could be used as an electrochemical sensor for the determination of CD in real samples, such as urine samples.

  12. Electrochemical Immunosensor Based on Fe3O4/PANI/AuNP Detecting Interface for Carcinoembryonic Antigen Biomarker

    Science.gov (United States)

    Amarasiri, Chamali; Nguyen, Thanh Binh; Nguyen, Loc Thai; Thu, Vu Thi; Thuy, Nguyen Thi My; Dai Lam, Tran

    2017-10-01

    A low-cost screen-printed carbon electrode (SPCE) modified with Fe3O4, gold nanoparticles (AuNPs), and polyaniline (PANI) has been developed for rapid measurement of carcinoembryonic antigen (CEA) biomarker. The electrode surface was covered with Fe3O4 nanoparticles by drop coating then with PANI via electropolymerization. The resulting surface was further modified by AuNPs via electrodeposition. Key factors affecting the electrochemical behavior and sensing performance of the electrode were investigated. The results demonstrated that Fe3O4 mass loading of 2 mg/cm2 and 15 cycles of PANI polymerization were optimal for electrochemical measurement of CEA biomarker. In addition, compared with bare SPCE, coating the electrode surface with PANI, Fe3O4/PANI, and Fe3O4/PANI/AuNP significantly enhanced the peak oxidation current by approximately 16%, 52%, and 93%, respectively. The sensors exhibited linear trends with CEA concentration from 0 ng/mL to 10 ng/mL. The limit of detection and sensitivity of the electrode were estimated to be 0.25 ng/mL and 0.3827 μA/ng mL-1, respectively. Such sensors could be easily integrated into microfluidic platforms and could serve as a low-cost, rapid, point-of-care measurement method for CEA cancer biomarker.

  13. Enhanced electrochemical detection of ketorolac tromethamine at polypyrrole modified glassy carbon electrode.

    Science.gov (United States)

    Santhosh, Padmanabhan; Senthil Kumar, Nagarajan; Renukadevi, Murugesan; Gopalan, Anantha Iyengar; Vasudevan, Thiyagarajan; Lee, Kwang-Pill

    2007-04-01

    A glassy carbon electrode modified with a coating of polypyrrole (Ppy) exhibited an attractive performance for the detection and determination of a non-steroidal and non-narcotic analgesic compound, ketorolac tromethamine (KT). Cyclic voltammetry, differential pulse and square wave voltammetry were used in a combined way to identify the electrochemical characteristics and to optimize the conditions for detection. For calibrating and estimating KT, square-wave voltammetry was mainly used. The drug shows a well-defined peak at -1.40 V vs. Ag/AgCl in the acetate buffer (pH 5.5). The existence of Ppy on the surface of the electrode gives higher electrochemical active sites at the electrode for the detection of KT and preconcentrate KT by adsorption. The square-wave stripping voltammetric response depends on the excitation signal and the accumulation time. The calibration curve is linear in the range 1 x 10(-11) to 1 x 10(-7) M with a detection limit of 1.0 x 10(-12) M. Applicability to serum samples was also demonstrated. A detection limit of 1.0 ng ml for serum was observed. Square-wave voltammetry shows superior performance over UV spectroscopy and other techniques.

  14. Magnetic Electrochemical Immunoassays with Quantum Dot Labels for Detection of Phosphorylated Acetylcholinesterase in Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hua; Wang, Jun; Timchalk, Charles; Lin, Yuehe

    2008-11-01

    A new magnetic electrochemical immunoassay has been developed as a tool for biomonitoring exposures to organophosphate (OP) compounds, e.g., insecticides and chemical nerve agents, by directly detecting organophosphorylated acetylcholinesterase (OP-AChE). This immunoassay uniquely incorporates highly efficient magnetic separation with ultrasensitive square wave voltammetry (SWV) analysis with quantum dots (QDs) as labels. A pair of antibodies was used to achieve the specific recognition of OP-AChE that was prepared with paraoxon as an OP model agent. Antiphosphoserine polyclonal antibodies were anchored on amorphous magnetic particles preferably chosen to capture OP-AChE from the sample matrixes by binding their phosphoserine moieties that were exposed through unfolding the protein adducts. This was validated by electrochemical examinations and enzyme-linked immunosorbent assays. Furthermore, antihuman AChE monoclonal antibodies were labeled with cadmium-source QDs to selectively recognize the captured OP-AChE, as characterized by transmission electron microscopy. The subsequent electrochemical SWV analysis of the cadmium component released by acid from the coupled QDs was conducted on disposable screen-printed electrodes. Experimental results indicated that the SWV-based immunoassays could yield a linear response over a broad concentration range of 0.3-300 ng/mL OP-AChE in human plasma with a detection limit of 0.15 ng/mL. Such a novel electrochemical immunoassay holds great promise as a simple, selective, sensitive, and field-deployable tool for the effective biomonitoring and diagnosis of potential exposures to nerve agents and pesticides.

  15. Integrated nuclear techniques to detect illicit materials

    Energy Technology Data Exchange (ETDEWEB)

    DeVolpi, A.

    1997-10-01

    This paper discusses the problem of detecting explosives in the context of an object being transported for illicit purposes. The author emphasizes that technologies developed for this particular application have payoffs in many related problem areas. The author discusses nuclear techniques which can be applied to this detection problem. These include: x-ray imaging; neutronic interrogation; inelastic neutron scattering; fieldable neutron generators. He discusses work which has been done on the applications of these technologies, including results for detection of narcotics. He also discusses efforts to integrate these techniques into complementary systems which offer improved performance.

  16. Integrated Lateral Flow Test Strip with Electrochemical Sensor for Quantification of Phosphorylated Cholinesterase: Biomarker of Exposure to Organophosphorus Agents

    Energy Technology Data Exchange (ETDEWEB)

    Du, Dan; Wang, Jun; Wang, Limin; Lu, Donglai; Lin, Yuehe

    2012-02-08

    An integrated lateral flow test strip with electrochemical sensor (LFTSES) device with rapid, selective and sensitive response for quantification of exposure to organophosphorus (OP) pesticides and nerve agents has been developed. The principle of this approach is based on parallel measurements of post-exposure and baseline acetylcholinesterase (AChE) enzyme activity, where reactivation of the phosphorylated AChE is exploited to enable measurement of total amount of AChE (including inhibited and active) which is used as a baseline for calculation of AChE inhibition. Quantitative measurement of phosphorylated adduct (OP-AChE) was realized by subtracting the active AChE from the total amount of AChE. The proposed LFTSES device integrates immunochromatographic test strip technology with electrochemical measurement using a disposable screen printed electrode which is located under the test zone. It shows linear response between AChE enzyme activity and enzyme concentration from 0.05 to 10 nM, with detection limit of 0.02 nM. Based on this reactivation approach, the LFTSES device has been successfully applied for in vitro red blood cells inhibition studies using chlorpyrifos oxon as a model OP agent. This approach not only eliminates the difficulty in screening of low-dose OP exposure because of individual variation of normal AChE values, but also avoids the problem in overlapping substrate specificity with cholinesterases and avoids potential interference from other electroactive species in biological samples. It is baseline free and thus provides a rapid, sensitive, selective and inexpensive tool for in-field and point-of-care assessment of exposures to OP pesticides and nerve agents.

  17. Electrochemical detection of amaranth in food based on the enhancement effect of carbon nanotube film.

    Science.gov (United States)

    Wang, Peng; Hu, Xiaozhong; Cheng, Qin; Zhao, Xiaoya; Fu, Xiaofang; Wu, Kangbing

    2010-12-08

    Amaranth is widely added to food and can cause many adverse health effects when it is excessively consumed. Therefore, the monitoring of amaranth is quite important. Herein, an electrochemical sensor for the sensitive and rapid detection of amaranth was reported using multiwall carbon nanotube (MWNT) as the sensing film. Due to the large surface area and high accumulation efficiency, the MWNT sensor showed a strong enhancement effect on the oxidation of amaranth, and greatly increased the current signal. The detection conditions such as pH value, amount of MWNT, accumulation potential and time were optimized. The linear range is from 40 nM to 0.8 μM, and the limit of detection is 35 nM. Finally, the new sensor was successfully employed to detect amaranth in soft drinks, and the results were tested by high-performance liquid chromatography.

  18. Determination of diarylheptanoids from Alpinia officinarum (Lesser Galangal) by HPLC with photodiode array and electrochemical detection.

    Science.gov (United States)

    Liu, Zhihua; Sang, Shengmin; Hartman, Thomas G; Ho, Chi-Tang; Rosen, Robert T

    2005-01-01

    Normal-phase column chromatography followed by semi-preparative reversed-phase HPLC has been used to isolate, from the rhizomes of Alpinia officinarum, five diarylheptanoids identified as 5-hydroxy-7-(4"-hydroxy-3"-methoxyphenyl)-1-phenyl-3-heptanone, 5-methoxy-7-(4"-hydroxy-3"-methoxyphenyl)-1-phenyl-3-heptanone, 7-(4"-hydroxyphenyl)-1-phenylhept-4-en-3-one, 7-(4"-hydroxy-3"-methoxyphenyl)-1-phenyl-hept-4-en-3-one, 1,7-diphenylhept-4-en-3-one. The levels of these five diarylheptanoids in root material were determined quantitatively by HPLC with UV detection and the assay methods so developed were simple, rapid and accurate. Four of the diarylheptanoids could also be detected by HPLC with electrochemical detection (ECD) in the oxidative mode, and ECD was found to have a higher sensitivity than photodiode array detection.

  19. Multiplexed Electrochemical Detection of Yersinia Pestis and Staphylococcal Enterotoxin B using an Antibody Microarray

    Directory of Open Access Journals (Sweden)

    Jason Wojciechowski

    2010-04-01

    Full Text Available The CombiMatrix antibody microarray is a versatile, sensitive detection platform based on the generation and transduction of electrochemical signals following antigen binding to surface antibodies. The sensor chip described herein is comprised of microelectrodes coupled to an adjacent bio-friendly matrix coated with antibodies to the biological pathogens Yersinia pestis and Bacillus anthracis, and the bacterial toxin staphylococcal enterotoxin B (SEB. Using this system, we were able to detect SEB and inactivated Y. pestis individually as well as in two-plex assays at concentrations as low as 5 pg/mL and 106 CFU/mL, respectively. We also introduce super avidin-biotin system (SABS as a viable and effective means to enhance assay signal responses and lower detection limits. Together these technologies represent substantial advances in point-of-care and point-of-use detection applications.

  20. Electrochemical Affinity Biosensors Based on Disposable Screen-Printed Electrodes for Detection of Food Allergens.

    Science.gov (United States)

    Vasilescu, Alina; Nunes, Gilvanda; Hayat, Akhtar; Latif, Usman; Marty, Jean-Louis

    2016-11-05

    Food allergens are proteins from nuts and tree nuts, fish, shellfish, wheat, soy, eggs or milk which trigger severe adverse reactions in the human body, involving IgE-type antibodies. Sensitive detection of allergens in a large variety of food matrices has become increasingly important considering the emergence of functional foods and new food manufacturing technologies. For example, proteins such as casein from milk or lysozyme and ovalbumin from eggs are sometimes used as fining agents in the wine industry. Nonetheless, allergen detection in processed foods is a challenging endeavor, as allergen proteins are degraded during food processing steps involving heating or fermentation. Detection of food allergens was primarily achieved via Enzyme-Linked Immuno Assay (ELISA) or by chromatographic methods. With the advent of biosensors, electrochemical affinity-based biosensors such as those incorporating antibodies and aptamers as biorecognition elements were also reported in the literature. In this review paper, we highlight the success achieved in the design of electrochemical affinity biosensors based on disposable screen-printed electrodes towards detection of protein allergens. We will discuss the analytical figures of merit for various disposable screen-printed affinity sensors in relation to methodologies employed for immobilization of bioreceptors on transducer surface.

  1. In situ DNA amplification with magnetic primers for the electrochemical detection of food pathogens.

    Science.gov (United States)

    Lermo, A; Campoy, S; Barbé, J; Hernández, S; Alegret, S; Pividori, M I

    2007-04-15

    A sensitive and selective genomagnetic assay for the electrochemical detection of food pathogens based on in situ DNA amplification with magnetic primers has been designed. The performance of the genomagnetic assay was firstly demonstrated for a DNA synthetic target by its double-hybridization with both a digoxigenin probe and a biotinylated capture probe, and further binding to streptavidin-modified magnetic beads. The DNA sandwiched target bound on the magnetic beads is then separated by using a magneto electrode based on graphite-epoxy composite. The electrochemical detection is finally achieved by an enzyme marker, anti-digoxigenin horseradish peroxidase (HRP). The novel strategy was used for the rapid and sensitive detection of polymerase chain reaction (PCR) amplified samples. Promising resultants were also achieved for the DNA amplification directly performed on magnetic beads by using a novel magnetic primer, i.e., the up PCR primer bound to magnetic beads. Moreover, the magneto DNA biosensing assay was able to detect changes at single nucleotide polymorphism (SNP) level, when stringent hybridization conditions were used. The reliability of the assay was tested for Salmonella spp., the most important pathogen affecting food safety.

  2. Electrically active magnetic nanoparticles as novel concentrator and electrochemical redox transducer in Bacillus anthracis DNA detection.

    Science.gov (United States)

    Pal, Sudeshna; Alocilja, Evangelyn C

    2010-12-15

    Magnetic polymer nanostructures are a new class of multifunctional nanomaterials that are recently being explored in biosensor devices. In this paper, for the first time we report the novel application of electrically active magnetic (EAM) nanoparticles as concentrator of DNA targets as well as electrochemical transducers for detection of the Bacillus anthracis protective antigen A (pag A) gene. The EAM nanoparticles are synthesized by chemical polymerization and have dimensions of 80-100 nm. The biosensor detection encompasses two sets of DNA probes that are specific to the target gene: the detector probe labeled with the EAM nanoparticles and the biotinylated capture probe. The DNA targets are double hybridized to the detector and the capture probes and concentrated from nonspecific DNA fragments by applying a magnetic field. Subsequently, the DNA sandwiched targets (EAM-detector probe-DNA target-capture probe-biotin) are captured on streptavidin modified screen printed carbon electrodes through the biotinylated capture probes. Detection is achieved electrochemically by measuring the oxidation-reduction signal of the EAM nanoparticles. Preliminary results indicate that the biosensor is able to detect the redox signal of the EAM nanoparticles at DNA concentrations as low as 0.01 ng/μl.

  3. Electrochemical detection of protein based on hybridization chain reaction-assisted formation of copper nanoparticles.

    Science.gov (United States)

    Zhao, Jing; Hu, Suisui; Cao, Ya; Zhang, Bin; Li, Genxi

    2015-04-15

    In this paper, we report an electrochemical method for highly sensitive and specific detection of protein based on hybridization chain reaction (HCR)-assisted formation of copper nanoparticles by using small molecule such as folate-linked DNA as probe. In the presence of target protein, taking folate receptor (FR) as the model protein in this study, its binding with folate can protect the probe DNA from exonuclease I-catalyzed degradation, thus the probe DNA can be immobilized onto the electrode surface through the hybridization with capture DNA, triggering HCR on the electrode surface. Subsequently, copper nanoparticles can be formed on the electrode surface by using long duplex DNA oligomers from HCR as templates. Furthermore, copper ions released from acid-dissolution of copper nanoparticles can catalyze the oxidation of ο-phenylenediamine by dissolved oxygen, leading to significant electrochemical responses. As a result, our method can sensitively detect FR in the linear range from 0.01ng/mL to 100ng/mL with a detection limit of 3pg/mL. It can also specifically distinguish the target protein in both buffer and complex serum samples. Since many other proteins can be assayed by changing the corresponding small molecule, this method may be promising for the development of the technique for protein detections. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Multiresidue analysis of phenylurea herbicides in environmental waters by capillary electrophoresis using electrochemical detection.

    Science.gov (United States)

    Chicharro, M; Bermejo, E; Sánchez, A; Zapardiel, A; Fernandez-Gutierrez, A; Arraez, D

    2005-05-01

    A rapid multiresidue method has been developed for the analysis of seven phenylurea herbicides in the presence of two s-triazines in environmental waters. A simple end-column electrochemical detector was used in combination with a commercially-available capillary electrophoresis instrument with UV detection. The determination of phenylurea pesticides using micellar electrokinetic capillary chromatography with electrochemical detection represents the first such determination that has been reported. In both detection systems, linear ranges were obtained for the seven phenylurea herbicides at concentrations lower than 2.0x10(-5) mol l(-1), in 0.020 mol l(-1) phosphoric acid at pH 7.0 and containing 0.020 mol l(-1) of sodium dodecylsulfate, in order to obtain selectivity in the additional separation by a micellar distribution process. Under these conditions a detection limit lower than 5.0x10(-6) mol l(-1) (0.25 pmol of pesticide) was achieved for most of them. The pesticides were resolved in less than 30 min.

  5. Label-free signal-on aptasensor for sensitive electrochemical detection of arsenite.

    Science.gov (United States)

    Cui, Lin; Wu, Jie; Ju, Huangxian

    2016-05-15

    A signal-on aptasensor was fabricated for highly sensitive and selective electrochemical detection of arsenite with a label-free Ars-3 aptamer self-assembled on a screen-printed carbon electrode (SPCE) via Au-S bond. The Ars-3 aptamer could adsorb cationic polydiallyldimethylammonium (PDDA) via electrostatic interaction to repel other cationic species. In the presence of arsenite, the change of Ars-3 conformation due to the formation of Ars-3/arsenite complex led to less adsorption of PDDA, and the complex could adsorb more positively charged [Ru(NH3)6](3+) as an electrochemically active indicator on the aptasensor surface, which produced a sensitive "turn-on" response. The target-induced structure switching could be used for sensitive detection of arsenite with a linear range from 0.2 nM to 100 nM and a detection limit down to 0.15 nM. Benefiting from Ars-3 aptamer, the proposed system exhibited excellent specificity against other heavy metal ions. The SPCE-based aptasensor exhibited the advantages of low cost and simple fabrication, providing potential application of arsenite detection in environment.

  6. Electrochemical Detection of Sequence-Specific DNA with the Amplification of Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    Yuzhong Zhang

    2011-01-01

    Full Text Available A sensitive electrochemical DNA biosensor was prepared based on mercaptoacetic acid (MAA/gold nanoparticles (AuNPs modified electrode. Probe DNA (NH2-DNA was covalently linked to the carboxyl group of MAA in the presence of 1-ethyl-3-(3-dimethylaminopropyl carbodiimide hydrochloride (EDC and N-hydroxyl-succinimide (NHS. Scanning electron microscopy (SEM and electrochemical impedance spectra (EIS were used to investigate the film assembly process. The DNA hybridization events were monitored by differential pulse voltammetry (DPV, and adriamycin was used as the electrochemical indicator. Also the factors influencing the performance of the DNA hybridization were investigated in detail. Under the optimal conditions, the signal was linearly changed with target DNA concentration increased from 5.0 × 10−13 to 1.0 × 10−9 M and had a detection limit of 1.7 × 10−13 M (signal/noise ratio of 3. In addition, the DNA biosensor showed good reproducibility and stability during DNA assay.

  7. Electrochemical analysis of gold-coated magnetic nanoparticles for detecting immunological interaction

    Science.gov (United States)

    Pham, Thao Thi-Hien; Sim, Sang Jun

    2010-01-01

    An electrochemical impedance immunosensor was developed for detecting the immunological interaction between human immunoglobulin (IgG) and protein A from Staphylococcus aureus based on the immobilization of human IgG on the surface of modified gold-coated magnetic nanoparticles. The nanoparticles with an Au shell and Fe oxide cores were functionalized by a self-assembled monolayer of 11-mercaptoundecanoic acid. The electrochemical analysis was conducted on the modified magnetic carbon paste electrodes with the nanoparticles. The magnetic nanoparticles were attached to the surface of the magnetic carbon paste electrodes via magnetic force. The cyclic voltammetry technique and electrochemical impedance spectroscopy measurements of the magnetic carbon paste electrodes coated with magnetic nanoparticles-human IgG complex showed changes in its alternating current (AC) response both after the modification of the surface of the electrode and the addition of protein A. The immunological interaction between human IgG on the surface of the modified magnetic carbon paste electrodes and protein A in the solution could be successfully monitored.

  8. Electrochemical analysis of gold-coated magnetic nanoparticles for detecting immunological interaction

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Thao Thi-Hien; Sim, Sang Jun, E-mail: simsj@skku.ed [Sungkyunkwan University, Nano-optics and Biomolecular Engineering National Laboratory, Department of Chemical Engineering (Korea, Republic of)

    2010-01-15

    An electrochemical impedance immunosensor was developed for detecting the immunological interaction between human immunoglobulin (IgG) and protein A from Staphylococcus aureus based on the immobilization of human IgG on the surface of modified gold-coated magnetic nanoparticles. The nanoparticles with an Au shell and Fe oxide cores were functionalized by a self-assembled monolayer of 11-mercaptoundecanoic acid. The electrochemical analysis was conducted on the modified magnetic carbon paste electrodes with the nanoparticles. The magnetic nanoparticles were attached to the surface of the magnetic carbon paste electrodes via magnetic force. The cyclic voltammetry technique and electrochemical impedance spectroscopy measurements of the magnetic carbon paste electrodes coated with magnetic nanoparticles-human IgG complex showed changes in its alternating current (AC) response both after the modification of the surface of the electrode and the addition of protein A. The immunological interaction between human IgG on the surface of the modified magnetic carbon paste electrodes and protein A in the solution could be successfully monitored.

  9. Electrochemical detection of nitrite on poly(pyronin Y)/graphene nanocomposites modified ITO substrate

    Science.gov (United States)

    Şinoforoğlu, Mehmet; Dağcı, Kader; Alanyalıoğlu, Murat; Meral, Kadem

    2016-06-01

    The present study reports on an easy preparation of poly(pyronin Y)/graphene (poly(PyY)/graphene) nanocomposites thin films on indium tin oxide coated glass substrates (ITO). The thin films of poly(PyY)/graphene nanocomposites are prepared by a novel method consisting of three steps; (i) preparation of graphene oxide (GO) thin films on ITO by spin-coating method, (ii) self-assembly of PyY molecules from aqueous solution onto the GO thin film, (iii) surface-confined electropolymerization (SCEP) of the adsorbed PyY molecules on the GO thin film. The as-prepared poly(PyY)/graphene nanocomposites thin films are characterized by using electroanalytical and spectroscopic techniques. Afterwards, the graphene-based polymeric dye thin film on ITO is used as an electrode in an electrochemical cell. Its performance is tested for electrochemical detection of nitrite. Under optimized conditions, the electrocatalytical effect of the nanocomposites thin film through electrochemical oxidation of nitrite is better than that of GO coated ITO.

  10. Electrochemical magneto immunosensor for the detection of anti-TG2 antibody in celiac disease.

    Science.gov (United States)

    Kergaravat, Silvina V; Beltramino, Luis; Garnero, Nidia; Trotta, Liliana; Wagener, Marta; Isabel Pividori, Maria; Hernandez, Silvia R

    2013-10-15

    An electrochemical magneto immunosensor for the detection of anti-transglutaminase antibodies (ATG2) in celiac disease was developed. The immunological reaction is performed on magnetic beads (MBs) as a solid support in which the transglutaminase enzyme (TG2) is covalently immobilized (TG2-MB) and then ATG2 were revealed by an antibody labeled with peroxidase. The electrochemical response of the enzymatic reaction with o-phenilendiamine and H₂O₂ as substrates by square wave voltammetry was correlated with the ATG2. Graphite-epoxi composite cylindrical electrodes and screen printed electrodes were used as transducers in the immunosensor. A total number of 29 sera from clinically confirmed cases of celiac disease and 19 negative control sera were tested by the electrochemical magneto immunosensor. The data were submitted to the receiver-operating characteristic plot (ROC) analysis which indicated that 16.95 units was the most effective cut-off value (COV) to discriminate correctly between celiac and non-celiac patients. Using this point for prediction, sensitivity was found to be 100%, while specificity was 84%.

  11. Detection of 2D phase transitions at the electrode/electrolyte interface using electrochemical impedance spectroscopy

    Science.gov (United States)

    Tymoczko, Jakub; Colic, Viktor; Bandarenka, Aliaksandr S.; Schuhmann, Wolfgang

    2015-01-01

    The capacitance of the electric double layer, CDL, formed at the electrode/electrolyte interface is generally determined by electrochemical impedance spectroscopy (EIS). However, CDL values obtained using EIS data often depend on the ac frequency of the potential perturbation used in EIS. The reasons for the observed frequency dispersions can be various, and hence extracting valuable information about the status of the electrified interface is not possible with the required certainty. In this work, using well-understood electrochemical systems, namely Pt(111) electrodes in contact with a series of acidic sulfate ions containing electrolytes, we provide strong evidence that 2D phase transitions in the adsorbate layers and, in general, structural effects at the electrode/electrolyte interface are in many cases responsible for the frequency dispersion of the double layer capacitance. These empirical findings open new opportunities for the detection and evaluation of 2D phase transition processes and other structural effects using EIS, even in presence of simultaneously occurring electrochemical processes. However, further theoretical elaboration of this effect is necessary.

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

    Science.gov (United States)

    Peng, Donglai; Hu, Bin; Kang, Mengmeng; Wang, Minghua; He, Linghao; Zhang, Zhihong; Fang, Shaoming

    2016-12-01

    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 Cu2+ 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 Cu2+ 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 Cu2+ resulting from the strong coordination chemistry between Cu2+ and RBH. The as-developed sensor towards detecting Cu2+ 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 Cu2+ detection. Therefore, the new strategy of the RBH-based electrochemical sensor exhibits great potential application in environment treatment and protection.

  13. Conveniently assembling dithiocarbamate and gold nanoparticles onto the gold electrode: A new type of electrochemical sensors for biomolecule detection

    Science.gov (United States)

    Li, Maoguo; Gao, Feng; Yang, Ping; Wang, Lun; Fang, Bin

    Dithiocarbamate and gold nanoparticles have been successfully assembled onto the surface of the gold electrode and a novel ultrastable chemical modified electrode (CME) was fabricated conveniently. The as-prepared CME was investigated by electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM) and quartz crystal microbalance (QCM), and its electrochemical behaviors for catalytic oxidation of dopamine (DA) was also observed by cyclic voltammetry (CV) and amperometric i- t curve. The results indicated that the novel surface has endowed the electrode with not only ultrastability but also the advantages of organic ligands and gold nanoparticles, which open up a new way to design high efficient and utility electrochemical sensors for biomolecule detection.

  14. Electrospun manganese (III) oxide nanofiber based electrochemical DNA-nanobiosensor for zeptomolar detection of dengue consensus primer.

    Science.gov (United States)

    Tripathy, Suryasnata; Krishna Vanjari, Siva Rama; Singh, Vikrant; Swaminathan, S; Singh, Shiv Govind

    2017-04-15

    Nanoscale biosensors, owing to their high-sensitivity and extremely low limits-of-detection, have enabled the realization of highly complex and sophisticated miniaturized platforms for several important healthcare applications, the most predominant one being disease diagnosis. In particular, nanomaterial facilitated electrochemical detection of DNA hybridization has had an exceptional impact on fields such as genetics and cancerous mutation detection Here we report an ultrasensitive electrochemical platform using electrospun semi-conducting Manganese (III) Oxide (Mn2O3) nanofibers for DNA Hybridization detection. The proposed platform coalesces the inherent advantages of metal-oxide nanofibers and electrochemical transduction techniques, resulting in label-free zeptomolar detection of DNA hybridization. As proof of concept, we demonstrate zeptomolar detection of Dengue consensus primer (limit of detection: 120×10(-21)M) both in control as well as spiked serum samples. Our reported detection limit is superior in comparison with previously reported electrochemical DNA hybridization sensors for Dengue virus detection, spanning both labeled and label-free transductions. This ultra-sensitivity, we believe, is a result of synthesizing a low bandgap electrospun metal-oxide nanomaterial corresponding to a specific oxidation state of Manganese. This methodology can be extended for detection of any hybridization of interest by simply adapting an appropriate functionalization protocol and thus is very generic in nature. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Convection of tin in a Bridgman system. II - An electrochemical method for detecting flow regimes

    Science.gov (United States)

    Sears, B.; Fripp, A. L.; Debnam, W. J., Jr.; Woodell, G. A.; Anderson, T. J.; Narayanan, R.

    1992-01-01

    An ampoule was designed in order to obtain local flow behavior of the flow fields for convection of tin in a vertical Bridgman configuration. Multiple electrochemical cells were located along the periphery of the ampoule. Oxygen was titrated into the ampoule at one of the cell locations using a potentiostat and the concentration of oxygen was monitored at the other cell locations by operating the cells in a galvanic mode. Onset of oscillations were detected by means of thermocouples. We conclude that the flows are generally three dimensional for an aspect ratio of 5. Results on oscillations concurred with those of earlier workers. Suggestions for improved designs were made.

  16. A Study on Tannic Acid-doped Polypyrrole Films on Gold Electrodes for Selective Electrochemical Detection of Dopamine

    OpenAIRE

    Shouzhuo Yao; Yunlong Li; Zhili Li; Qingji Xie; Ling Jiang

    2005-01-01

    Tannic acid-doped polypyrrole (PPY/TA) films have been grown on gold electrodes for selective electrochemical detection of dopamine (DA). Electrochemical quartz crystal microbalance (EQCM) studies revealed that, in vivid contrast to perchlorate-doped polypyrrole films (PPY/ClO4 -), the redox switching of PPY/TA films in aqueous solutions involved only cation transport if the solution pH was greater than 3∼4. The PPY/TA Au electrodes also exhibited attractive permselectivity for electroactive ...

  17. Ultrasensitive Detection of Ferulic Acid Using Poly(diallyldimethylammonium chloride Functionalized Graphene-Based Electrochemical Sensor

    Directory of Open Access Journals (Sweden)

    Lin-jie Liu

    2014-01-01

    Full Text Available The electrochemical redox of ferulic acid (FA was investigated systematically by cyclic voltammetry (CV with a poly(diallyldimethylammonium chloride functionalized graphene-modified glassy carbon electrode (PDDA-G/GCE as a working electrode. A simple and sensitive differential pulse voltammetry (DPV technique was proposed for the direct quantitative determination of FA in Angelica sinensis and spiked human urine samples for the first time. The dependence of the intensities of currents and potentials on nature of the supporting electrolyte, pH, scan rate, and concentration was investigated. Under optimal conditions, the proposed sensor exhibited excellent electrochemical sensitivity to FA, and the oxidation peak current was proportional to FA concentration in the range of 8.95×10-8 M ~5.29×10-5 M, with a relatively low detection limit of 4.42×10-8 M. This fabricated sensor also displayed acceptable reproducibility, long-term stability, and high selectivity with negligible interferences from common interfering species. Besides, it was applied to detect FA in Angelica sinensis and biological samples with satisfactory results, making it a potential alternative tool for the quantitative detection of FA in pharmaceutical analysis.

  18. Selective detection of dopamine with an all PEDOT:PSS Organic Electrochemical Transistor

    Science.gov (United States)

    Gualandi, Isacco; Tonelli, Domenica; Mariani, Federica; Scavetta, Erika; Marzocchi, Marco; Fraboni, Beatrice

    2016-10-01

    An all PEDOT:PSS Organic Electrochemical Transistor (OECT) has been developed and used for the selective detection of dopamine (DA) in the presence of interfering compounds (ascorbic acid, AA and uric acid, UA). The selective response has been implemented using a potentiodynamic approach, by varying the operating gate voltage and the scan rate. The trans-conductance curves allow to obtain a linear calibration plot for AA, UA and DA and to separate the redox waves associated to each compound; for this purpose, the scan rate is an important parameter to achieve a good resolution. The sensitivities and limits of detection obtained with the OECT have been compared with those obtained by potential step amperometric techniques (cyclic voltammetry and differential pulse voltammetry), employing a PEDOT:PSS working electrode: our results prove that the all-PEDOT:PSS OECT sensitivities and limits of detection are comparable or even better than those obtained by DPV, a technique that employs a sophisticate potential wave and read-out system in order to maximize the performance of electrochemical sensors and that can hardly be considered a viable readout method in practical applications.

  19. Disordered array of Au covered Silicon nanowires for SERS biosensing combined with electrochemical detection

    Science.gov (United States)

    Convertino, Annalisa; Mussi, Valentina; Maiolo, Luca

    2016-04-01

    We report on highly disordered array of Au coated silicon nanowires (Au/SiNWs) as surface enhanced Raman scattering (SERS) probe combined with electrochemical detection for biosensing applications. SiNWs, few microns long, were grown by plasma enhanced chemical vapor deposition on common microscope slides and covered by Au evaporated film, 150 nm thick. The capability of the resulting composite structure to act as SERS biosensor was studied via the biotin-avidin interaction: the Raman signal obtained from this structure allowed to follow each surface modification step as well as to detect efficiently avidin molecules over a broad range of concentrations from micromolar down to the nanomolar values. The metallic coverage wrapping SiNWs was exploited also to obtain a dual detection of the same bioanalyte by electrochemical impedance spectroscopy (EIS). Indeed, the SERS signal and impedance modifications induced by the biomolecule perturbations on the metalized surface of the NWs were monitored on the very same three-electrode device with the Au/SiNWs acting as both working electrode and SERS probe.

  20. Direct electrochemical stripping detection of cystic-fibrosis-related DNA linked through cadmium sulfide quantum dots

    Science.gov (United States)

    Marin, Sergio; Merkoçi, Arben

    2009-02-01

    Electrochemical detection of a cadmium sulfide quantum dots (CdS QDs)-DNA complex connected to paramagnetic microbeads (MB) was performed without the need for chemical dissolving. The method is based on dropping 20 µl of CdS QD-DNA-MB suspension on the surface of a screen-printed electrode. It is followed by magnetic collection on the surface of the working electrode and electrochemical detection using square-wave voltammetry (SWV), giving a well-shaped and sensitive analytical signal. A cystic-fibrosis-related DNA sequence was sandwiched between the two DNA probes. One DNA probe is linked via biotin-streptavidin bonding with MB and the other one via thiol groups with the CdS QD used as tags. Nonspecific signals of DNA were minimized using a blocking agent and the results obtained were successfully employed in a model DNA sensor with an interest in future applications in the clinical field. The developed nanoparticle biosensing system may offer numerous opportunities in other fields where fast, low cost and efficient detection of small volume samples is required.

  1. Graphene electrode modified with electrochemically reduced graphene oxide for label-free DNA detection.

    Science.gov (United States)

    Li, Bing; Pan, Genhua; Avent, Neil D; Lowry, Roy B; Madgett, Tracey E; Waines, Paul L

    2015-10-15

    A novel printed graphene electrode modified with electrochemically reduced graphene oxide was developed for the detection of a specific oligonucleotide sequence. The graphene oxide was immobilized onto the surface of a graphene electrode via π-π bonds and electrochemical reduction of graphene oxide was achieved by cyclic voltammetry. A much higher redox current was observed from the reduced graphene oxide-graphene double-layer electrode, a 42% and 36.7% increase, respectively, in comparison with that of a bare printed graphene or reduced graphene oxide electrode. The good electron transfer activity is attributed to a combination of the large number of electroactive sites in reduced graphene oxide and the high conductivity nature of graphene. The probe ssDNA was further immobilized onto the surface of the reduced graphene oxide-graphene double-layer electrode via π-π bonds and then hybridized with its target cDNA. The change of peak current due to the hybridized dsDNA could be used for quantitative sensing of DNA concentration. It has been demonstrated that a linear range from 10(-7)M to 10(-12)M is achievable for the detection of human immunodeficiency virus 1 gene with a detection limit of 1.58 × 10(-13)M as determined by three times standard deviation of zero DNA concentration.

  2. Amine functionalized graphene oxide/CNT nanocomposite for ultrasensitive electrochemical detection of trinitrotoluene.

    Science.gov (United States)

    Sablok, Kavita; Bhalla, Vijayender; Sharma, Priyanka; Kaushal, Roohi; Chaudhary, Shilpa; Suri, C Raman

    2013-03-15

    Binding of electron-deficient trinitrotoluene (TNT) to the electron rich amine groups on a substrate form specific charge-transfer Jackson-Meisenheimer (JM) complex. In the present work, we report formation of specific JM complex on amine functionalized reduced graphene oxide/carbon nanotubes- (a-rGO/CNT) nanocomposite leading to sensitive detection of TNT. The CNT were dispersed using graphene oxide that provides excellent dispersion by attaching to CNT through its hydrophobic domains and solubilizes through the available OH and COOH groups on screen printed electrode (SPE). The GO was reduced electrochemically to form reduced graphene that remarkably increases electrochemical properties owing to the intercalation of high aspect CNT on graphene flakes as shown by TEM micrograph. The surface amine functionalization of dropcasted and rGO/CNT was carried out using a bi-functional cross linker ethylenediamine. The extent of amine functionalization on modified electrodes was confirmed using energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS) and confocal microscopy. The FTIR and Raman spectra further suggested the formation of JM complex between amine functionalized electrodes and TNT leading to a shift in peak intensity together with peak broadening. The a-rGO/CNT nanocomposite prepared electrode surface leads to ultra-trace detection of TNT upto 0.01 ppb with good reproducibility (n=3). The a-rGO/CNT sensing platform could be an alternate for sensitive detection of TNT explosive for various security and environmental applications.

  3. Methionine – Au Nanoparticle Modified Glassy Carbon Electrode: a Novel Platform for Electrochemical Detection of Hydroquinone

    Directory of Open Access Journals (Sweden)

    Jiahong HE

    2014-12-01

    Full Text Available A high sensitive electrochemical sensor based on methionine/gold nanoparticles (MET/AuNPs modified glassy carbon electrode (GCE was fabricated for the quantitative detection of hydroquinone (HQ. The as-modified electrode was characterized by scanning electron microscopy (SEM and X-ray diffraction (XRD techniques. The electrochemical performance of the sensor to HQ was investigated by using cyclic and differential pulse voltammetry, which revealed its excellent electrocatalytic activity and reversibility towards HQ. The separation of anodic and cathodic peak (∆Ep was decreased from 471 mV to 75 mV. The anodic peak current achieved under the optimum conditions was linear with the HQ concentration ranging from 8 μM to 400 μM with the detection limit 0.12 μM (3σ. The as-fabricated sensor also showed a good selectivity towards HQ without demonstrating interference from other coexisting species. Furthermore, the sensor showed a good performance for HQ detection in environmental water, which suggests its potential practical application. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6477

  4. Redox cycling amplified electrochemical detection of DNA hybridization: application to pathogen E. coli bacterial RNA.

    Science.gov (United States)

    Walter, Anne; Wu, Jie; Flechsig, Gerd-Uwe; Haake, David A; Wang, Joseph

    2011-03-09

    An electrochemical genosensor in which signal amplification is achieved using p-aminophenol (p-AP) redox cycling by nicotinamide adenine dinucleotide (NADH) is presented. An immobilized thiolated capture probe is combined with a sandwich-type hybridization assay, using biotin as a tracer in the detection probe, and streptavidin-alkaline phosphatase as reporter enzyme. The phosphatase liberates the electrochemical mediator p-AP from its electrically inactive phosphate derivative. This generated p-AP is electrooxidized at an Au electrode modified self-assembled monolayer to p-quinone imine (p-QI). In the presence of NADH, p-QI is reduced back to p-AP, which can be re-oxidized on the electrode and produce amplified signal. A detection limit of 1 pM DNA target is offered by this simple one-electrode, one-enzyme format redox cycling strategy. The redox cycling design is applied successfully to the monitoring of the 16S rRNA of E. coli pathogenic bacteria, and provides a detection limit of 250 CFU μL(-1). Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Aptamer/quantum dot-based simultaneous electrochemical detection of multiple small molecules

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Haixia [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Jiang Bingying [School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400040 (China); Xiang Yun, E-mail: yunatswu@swu.edu.cn [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Zhang Yuyong; Chai Yaqin [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Yuan Ruo, E-mail: yuanruo@swu.edu.cn [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)

    2011-03-04

    A novel strategy for 'signal on' and sensitive one-spot simultaneous detection of multiple small molecular analytes based on electrochemically encoded barcode quantum dot (QD) tags is described. The target analytes, adenosine triphosphate (ATP) and cocaine, respectively, are sandwiched between the corresponding set of surface-immobilized primary binding aptamers and the secondary binding aptamer/QD bioconjugates. The captured QDs yield distinct electrochemical signatures after acid dissolution, whose position and size reflect the identity and level, respectively, of the corresponding target analytes. Due to the inherent amplification feature of the QD labels and the 'signal on' detection scheme, as well as the sensitive monitoring of the metal ions released upon acid dissolution of the QD labels, low detection limits of 30 nM and 50 nM were obtained for ATP and cocaine, respectively, in our assays. Our multi-analyte sensing system also shows high specificity to target analytes and promising applicability to complex sample matrix, which makes the proposed assay protocol an attractive route for screening of small molecules in clinical diagnosis.

  6. Electrochemical Sandwich Immunoassay for the Ultrasensitive Detection of Human MUC1 Cancer Biomarker

    Directory of Open Access Journals (Sweden)

    Zahra Taleat

    2013-01-01

    Full Text Available A new electrochemical sandwich immunoassay for the ultrasensitive detection of human MUC1 cancer biomarker using protein G-functionalized magnetic beads (MBs and graphite-based screen-printed electrodes (SPEs was developed. Magnetic beads were employed as the platforms for the immobilization and immunoreaction process. A pair of primary and secondary antibodies was used to capture the MUC1 protein. After labeling with a third antibody conjugated with horseradish peroxidase (HRP, the resulting conjugate was trapped at the surface of the graphite-based SPEs and MUC1 determination was carried out by differential pulse voltammetry (DPV at 0.4 V upon H2O2 addition using acetaminophen (APAP as the redox mediator. A linear relationship was obtained for the detection of human MUC1 over a range of 0–25 ppb with the lowest detection limit of 1.34 ppb when HRP was applied as a label. Preliminary experiments were performed using disposable electrochemical sensors in order to optimize some parameters (i.e., incubation times, concentrations, and blocking agent.

  7. Nickel nanoparticle-modified electrode for ultra-sensitive electrochemical detection of insulin.

    Science.gov (United States)

    Yu, Yanan; Guo, Meisong; Yuan, Mengwei; Liu, Weitong; Hu, Jingbo

    2016-03-15

    An ultra-sensitive electrochemical sensor for the detection of insulin was fabricated, using low-cost and environmentally friendly nickel nanoparticles (NiNPs) by ion implantation. The morphology and structure of the NiNPs are characterized by scanning electron microscopy (SEM), revealing diameters ranging from 4 to 8 nm. The insulin assay performances were evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (I-t). The NiNPs-modified indium tin oxide electrode (NiNPs/ITO) showed excellent analytical features, including ultra-high sensitivity (2140 μAμM(-1)) for detecting low concentrations of insulin, an incredibly low detection limit (10 pM) and a wide dynamic range (100 pM to 2400 pM and 1 nM to 125 nM). In addition, the NiNPs/ITO electrode was also used to analyze the insulin concentration in bovine insulin injections. The NiNPs/ITO electrode is expected to be used as a potential biosensor for insulin.

  8. Integration of Acoustic Detection Equipment into ANTARES

    CERN Document Server

    Lahmann, R; Graf, K; Hoessl, J; Kappes, A; Karg, T; Katz, U; Naumann, C; Salomon, K

    2005-01-01

    The ANTARES group at the University of Erlangen is working towards the integration of a set of acoustic sensors into the ANTARES Neutrino Telescope. With this setup, tests of acoustic particle detection methods and background studies shall be performed. The ANTARES Neutrino Telescope, which is currently being constructed in the Mediterranean Sea, will be equipped with the infrastructure to accommodate a 3-dimensional array of photomultipliers for the detection of Cherenkov light. Within this infrastructure, the required resources for acoustic sensors are available: Bandwidth for the transmission of the acoustic data to the shore, electrical power for the off-shore electronics and physical space to install the acoustic sensors and to route the connecting cables (transmitting signals and power) into the electronics containers. It will be explained how the integration will be performed with minimal modifications of the existing ANTARES design and which setup is foreseen for the acquisition of the acoustic data.

  9. A disposable electrochemical sensor based on protein G for High-Density Lipoprotein (HDL) detection.

    Science.gov (United States)

    Chammem, H; Hafaid, I; Bohli, N; Garcia, A; Meilhac, O; Abdelghani, A; Mora, L

    2015-11-01

    In this work, two biosensors were developed for the detection of High-Density Lipoproteins (HDL) particles, which are biomarkers inversely correlated with cardiovascular risk and which represent therapeutic targets for atherosclerosis. The electrochemical properties of the grafted antibody on interdigitated gold electrode were achieved by Impedance Spectroscopy (IS). The used deposition method was based on oriented antibody Anti-ApoA1 with an intermediate thin layer of protein G. The developed biosensor was able to detect both native plasma HDL and reconstituted HDL (rHDL) particles respectively with the detection limit of 50n g/mL and 1 ng/mL, respectively. Dynamic contact angle and atomic force microscopy were used. The developed biosensors are able to differentiate the HDL particles according to their differences in size and interactions with the immobilized antibody.

  10. Detection of methotrexate in a flow system using electrochemical impedance spectroscopy and multivariate data analysis.

    Science.gov (United States)

    Tesfalidet, Solomon; Geladi, Paul; Shimizu, Kenichi; Lindholm-Sethson, Britta

    2016-03-31

    Methotrexate (MTX), a common pharmaceutical drug in cancer therapy and treatment of rheumatic diseases, is known to cause severe adverse side effects at high dose. As the side effect may be life threatening, there is an urgent need for a continuous, bed-side monitoring of the nominal MTX serum level in a patient while the chemical is being administered. This article describes a detection of MTX using a flow system that consists two modified gold electrodes. Interaction of MTX with the antibodies fixed on the electrode surface is detected by electrochemical impedance spectroscopy and evaluated using singular value decomposition (SVD). The key finding of this work is that the change in the electrode capacitance is found to be quantitative with respect to the concentration of MTX. Moreover a calibration curve constructed using the principal component regression method has a linear range of six orders of magnitude and a detection limit of 1.65 × 10(-10) M.

  11. Ultrasensitive Label-free Electrochemical Immunosensor based on Multifunctionalized Graphene Nanocomposites for the Detection of Alpha Fetoprotein

    Science.gov (United States)

    Wang, Yaoguang; Zhang, Yong; Wu, Dan; Ma, Hongmin; Pang, Xuehui; Fan, Dawei; Wei, Qin; Du, Bin

    2017-01-01

    In this work, a novel label-free electrochemical immunosensor was developed for the quantitative detection of alpha fetoprotein (AFP). Multifunctionalized graphene nanocomposites (TB-Au-Fe3O4-rGO) were applied to modify the electrode to achieve the amplification of electrochemical signal. TB-Au-Fe3O4-rGO includes the advantages of graphene, ferroferric oxide nanoparticles (Fe3O4 NPs), gold nanoparticles (Au NPs) and toluidine blue (TB). As a kind of redox probe, TB can produce the electrochemical signal. Graphene owns large specific surface area, high electrical conductivity and good adsorption property to load a large number of TB. Fe3O4 NPs have good electrocatalytic performance towards the redox of TB. Au NPs have good biocompatibility to capture the antibodies. Due to the good electrochemical performance of TB-Au-Fe3O4-rGO, the effective and sensitive detection of AFP was achieved by the designed electrochemical immunosensor. Under optimal conditions, the designed immunosensor exhibited a wide linear range from 1.0 × 10−5 ng/mL to 10.0 ng/mL with a low detection limit of 2.7 fg/mL for AFP. It also displayed good electrochemical performance including good reproducibility, selectivity and stability, which would provide potential applications in the clinical diagnosis of other tumor markers. PMID:28186128

  12. Disposable Carbon Dots Modified Screen Printed Carbon Electrode Electrochemical Sensor Strip for Selective Detection of Ferric Ions

    Directory of Open Access Journals (Sweden)

    Shao Chien Tan

    2017-01-01

    Full Text Available A disposable electrochemical sensor strip based on carbon nanodots (C-Dots modified screen printed carbon electrode (SPCE was fabricated for selective detection of ferric ions (Fe3+ in aqueous solution. C-Dots of mean diameters within the range of 1–7 nm were synthesized electrochemically from spent battery carbon rods. The analytical performance of this electrochemical sensor strip was characterized using cyclic voltammetry (CV and electrochemical impedance spectroscopy (EIS. The deposition of C-Dots had enhanced the electron-transfer kinetics and current intensity of the SPCE remarkably by 734% as compared to that of unmodified SPCE. Under optimized conditions, the electrochemical sensor strip exhibited a linear detection range of 0.5 to 25.0 ppm Fe3+ with a limit of detection (LOD of 0.44±0.04 ppm (at S/N ratio = 3. Validation of results by the electrochemical sensor strip was done by comparing analysis results obtained using an Atomic Absorption Spectrometer (AAS.

  13. Fermi detected blazars seen by INTEGRAL

    CERN Document Server

    Beckmann, V; Soldi, S

    2009-01-01

    Multiwavelength observations are essential to constrain physical parameters of the blazars observed by Fermi/LAT. Among the 187 AGN significantly detected in public INTEGRAL data above 20 keV by the imager IBIS/ISGRI, 20 blazars were detected. 15 of these sources allowed significant spectral extraction. They show hard X-ray spectra with an average photon index of 2.1+-0.1 and a hard X-ray luminosity of L(20-100 keV) = 1.3e46 erg/s. 15 of the INTEGRAL blazars are also visible in the first 16 months of the Fermi/LAT data, thus allowing to constrain the inverse Compton branch in these cases. Among others, we analyse the LAT data of four blazars which were not included in the Fermi LAT Bright AGN Sample based on the first 3 months of the mission: QSO B0836+710, H 1426+428, RX J1924.8-2914, and PKS 2149-306. Especially for blazars during bright outbursts, as already observed simultaneously by INTEGRAL and Fermi (e.g. 3C 454.3 and Mrk 421), INTEGRAL provides unique spectral coverage up to several hundred keV. We pr...

  14. Palladium Nanoparticle Incorporated Porous Activated Carbon: Electrochemical Detection of Toxic Metal Ions.

    Science.gov (United States)

    Veerakumar, Pitchaimani; Veeramani, Vediyappan; Chen, Shen-Ming; Madhu, Rajesh; Liu, Shang-Bin

    2016-01-20

    A facile method has been developed for fabricating selective and sensitive electrochemical sensors for the detection of toxic metal ions, which invokes incorporation of palladium nanoparticles (Pd NPs) on porous activated carbons (PACs). The PACs, which were derived from waste biomass feedstock (fruit peels), possess desirable textural properties and porosities favorable for dispersion of Pd NPs (ca. 3-4 nm) on the graphitic PAC substrate. The Pd/PAC composite materials so fabricated were characterized by a variety of different techniques, such as X-ray diffraction, field-emission transmission electron microscopy, gas physisorption/chemisorption, thermogravimetric analysis, and Raman, Fourier-transform infrared, and X-ray photon spectroscopies. The Pd/PAC-modified glassy carbon electrodes (GCEs) were exploited as electrochemical sensors for the detection of toxic heavy metal ions, viz., Cd(2+), Pb(2+), Cu(2+), and Hg(2+), which showed superior performances for both individual as well as simultaneous detections. For simultaneous detection of Cd(2+), Pb(2+), Cu(2+), and Hg(2+), a linear response in the ion concentration range of 0.5-5.5, 0.5-8.9, 0.5-5.0, and 0.24-7.5 μM, with sensitivity of 66.7, 53.8, 41.1, and 50.3 μA μM(-1) cm(-2), and detection limit of 41, 50, 66, and 54 nM, respectively, was observed. Moreover, the Pd/PAC-modified GCEs also show perspective applications in detection of metal ions in real samples, as illustrated in this study for a milk sample.

  15. Electrochemical detection of p-aminophenol by flexible devices based on multi-wall carbon nanotubes dispersed in electrochemically modified Nafion.

    Science.gov (United States)

    Scandurra, Graziella; Antonella, Arena; Ciofi, Carmine; Saitta, Gaetano; Lanza, Maurizio

    2014-05-21

    A conducting composite prepared by dispersing multi-walled carbon nanotubes (MWCNTs) into a host matrix consisting of Nafion, electrochemically doped with copper, has been prepared, characterized and used to modify one of the gold electrodes of simply designed electrochemical cells having copier grade transparency sheets as substrates. Electrical measurements performed in deionized water show that the Au/Nafion/Au-MWCNTs-Nafion:Cu cells can be successfully used in order to detect the presence of p-aminophenol (PAP) in water, without the need for any supporting electrolyte. The intensity of the redox peaks arising when PAP is added to deionized water is found to be linearly related to the analyte in the range from 0.2 to 1.6 µM, with a detection limit of 90 nM and a sensitivity of 7 µA·(µM(-1))·cm(-2).

  16. Electrochemical Detection of p-Aminophenol by Flexible Devices Based on Multi-Wall Carbon Nanotubes Dispersed in Electrochemically Modified Nafion

    Directory of Open Access Journals (Sweden)

    Graziella Scandurra

    2014-05-01

    Full Text Available A conducting composite prepared by dispersing multi-walled carbon nanotubes (MWCNTs into a host matrix consisting of Nafion, electrochemically doped with copper, has been prepared, characterized and used to modify one of the gold electrodes of simply designed electrochemical cells having copier grade transparency sheets as substrates. Electrical measurements performed in deionized water show that the Au/Nafion/Au-MWCNTs–Nafion:Cu cells can be successfully used in order to detect the presence of p-aminophenol (PAP in water, without the need for any supporting electrolyte. The intensity of the redox peaks arising when PAP is added to deionized water is found to be linearly related to the analyte in the range from 0.2 to 1.6 µM, with a detection limit of 90 nM and a sensitivity of 7 µA·(µM−1·cm−2.

  17. Detection EGFR exon 19 status of lung cancer patients by DNA electrochemical biosensor.

    Science.gov (United States)

    Xu, Xiong-Wei; Weng, Xiu-Hua; Wang, Chang-Lian; Lin, Wei-Wei; Liu, Ai-Lin; Chen, Wei; Lin, Xin-Hua

    2016-06-15

    Epidermal growth factor receptor (EGFR) exon 19 mutation status is a very important prediction index for tyrosine kinase inhibitors (TKIs) therapy. In this paper, we constructed a superior selective sandwich-type electrochemical biosensor to detect in-frame deletions in exon 19 of EGFR in real samples of patients with non-small cell lung carcinoma. Based on the characteristics of different hybridization efficiency in different hybridization phase conditions, different region around EGFR exon 19 deletion hotspots was selected to design DNA probes to improve biosensor performance. The results confirm that alteration of deletion location in target deliberately according to different hybridization phase is able to improve selectivity of sandwich-type DNA biosensor. Satisfactory discrimination ability can be achieved when the deletions are located in the capture probe interaction region. In order to improve efficiency of ssDNA generation from dsDNA, we introduce Lambda exonuclease (λ-exo) to sandwich-type biosensor system. EGFR exon 19 statuses of clinical real samples from lung cancer patients can be discriminated successfully by the proposed method. Our research would make the electrochemical biosensor be an excellent candidate for EGFR detection for lung cancer patients.

  18. Multichannel bipotentiostat integrated with a microfluidic platform for electrochemical real-time monitoring of cell cultures.

    Science.gov (United States)

    Vergani, Marco; Carminati, Marco; Ferrari, Giorgio; Landini, Ettore; Caviglia, Claudia; Heiskanen, Arto; Comminges, Clément; Zór, Kinga; Sabourin, David; Dufva, Martin; Dimaki, Maria; Raiteri, Roberto; Wollenberger, Ulla; Emneus, Jenny; Sampietro, Marco

    2012-10-01

    An electrochemical detection system specifically designed for multi-parameter real-time monitoring of stem cell culturing/differentiation in a microfluidic system is presented. It is composed of a very compact 24-channel electronic board, compatible with arrays of microelectrodes and coupled to a microfluidic cell culture system. A versatile data acquisition software enables performing amperometry, cyclic voltammetry and impedance spectroscopy in each of the 12 independent chambers over a 100 kHz bandwidth with current resolution down to 5 pA for 100 ms measuring time. The design of the platform, its realization and experimental characterization are reported, with emphasis on the analysis of impact of input capacitance (i.e., microelectrode size) and microfluidic pump operation on current noise. Programmable sequences of successive injections of analytes (ferricyanide and dopamine) and rinsing buffer solution as well as the impedimetric continuous tracking for seven days of the proliferation of a colony of PC12 cells are successfully demonstrated.

  19. Graphene/SnO2 nanocomposite-modified electrode for electrochemical detection of dopamine

    Directory of Open Access Journals (Sweden)

    R. Nurzulaikha

    2015-09-01

    Full Text Available A graphene-tin oxide (G-SnO2 nanocomposite was prepared via a facile hydrothermal route using graphene oxide and Sn precursor solution without addition of any surfactant. The hydrothermally synthesized G-SnO2 nanocomposite was characterized using a field emission scanning electron microscope (FESEM, high resolution transmission electron microscope (HRTEM, X-ray diffraction (XRD, and energy dispersive spectroscopy (EDS. A homogeneous deposition of SnO2 nanoparticles with an average particle size of 10 nm on the graphene was observed in the FESEM and HRTEM images. The G-SnO2 nanocomposite was used to fabricate a modified electrode for the electrochemical detection of dopamine (DA in the presence of ascorbic acid (AA. Differential pulse voltammetry (DPV showed a limit of detection (LoD of 1 μM (S/N = 3 in the presence of ascorbic acid (AA.

  20. Electrochemical Detecting Lung Cancer-Associated Antigen Based on Graphene-Gold Nanocomposite

    Directory of Open Access Journals (Sweden)

    Zheng Wei

    2017-03-01

    Full Text Available Using a Au nanoparticle/reduced graphene oxide composite (AuNP-RGO, a signal-enhanced electrochemical immunosensor without label was created to detect neuron-specific enolase (NSE. Furthermore, an environmentally-friendly method was developed to prepare AuNP-RGO by employing chitosan (CS, which served as reducing and stabilizing agent. We showed that the sensitivity of the immunosensor designed in this report was remarkably enhanced because of the numerous active sites in the sensor provided by the AuNP-RGO nanostructure. For the quantification of NSE, the immunosensor exhibited a positive linear relationship with the concentration in the range of 0.1 to 2000 ng/mL, where the limit of the detection was 0.05 ng/mL.

  1. DNA duplex membrane effect for the electrochemical detection of single-base DNA mutations

    Institute of Scientific and Technical Information of China (English)

    Luo Chunxiong; Mao Yongdong; Ouyang Qi

    2006-01-01

    Here we report a new method to detect DNA point mutations.The method is based on the formation and deformation of double-stranded DNA(dsDNA)membranes on a gold surface.It can encage reporter molecules between the gold surface and the double-stranded DNA or keep them away from the gold surface.In these systems,Fe(CN)63- was used as the reporter.As the temperature increases,a sharp electrochemical signal change in the melting curve of wild-type dsDNA appears.At a special temperature,the and single base mutation target.Thus,the system provides a simple and sensitive method to detect DNA point mutations without labeling targets.

  2. Development of electrochemical impedance spectroscopy based sensing system for DEHP detection

    KAUST Repository

    Zia, Asif I.

    2011-11-01

    This research work presents a real time and non invasive technique to detect Di(2-ethylhexyl) phthalate (DEHP)content in purified water and quantify its concentration by Electrochemical Impedance Spectroscopy(E.I.S.). Planar Inter-digital capacitive sensor is employed to evaluate conductivity, permeability and dielectric properties of material under test. This sensor, consisting of inter-digitated microelectrodes, is fabricated on silicon substrate using thin-film Microelectromechanical system (MEMS) based semiconductor device fabrication technology. Impedance spectrums are obtained with various concentrations of DEHP in purified water by using an electric circuit in order to extract sample conductance. Relationship of sample conductance with DEHP concentration is studied in this research work which enables us to show the ability of E.I.S. to detect DEHP concentration in water and hence can be applied in water treatment process for contamination quantification. © 2011 IEEE.

  3. Eco-friendly electrochemical lab-on-paper for heavy metal detection.

    Science.gov (United States)

    Medina-Sánchez, Mariana; Cadevall, Miquel; Ros, Josep; Merkoçi, Arben

    2015-11-01

    A disposable electrochemical lateral flow paper-based sensing device for heavy metal detection is proposed. The quantification of lead and cadmium in aqueous samples is demonstrated in a range from 10 to 100 ppb with a limit of detection of 7 and 11 ppb respectively. Moreover, the platform itself, which is made of paper, served as a sample pretreatment material due to its filtering properties. Real samples, especially in which the matrix is usually turbid and would in principle need a previous filtration, are successfully analyzed. This lab-on-paper device is simple, low cost, easy to fabricate, and portable, being a promising tool for new point-of-care applications in environmental monitoring, public health, and food safety.

  4. LDHs as electrode materials for electrochemical detection and energy storage: supercapacitor, battery and (bio)-sensor.

    Science.gov (United States)

    Mousty, Christine; Leroux, Fabrice

    2012-11-01

    From an exhaustive overview based on applicative academic literature and patent domain, the relevance of Layered Double Hydroxide (LDHs) as electrode materials for electrochemical detection of organic molecules having environmental or health impact and energy storage is evaluated. Specifically the focus is driven on their application as supercapacitor, alkaline or lithium battery and (bio)-sensor. Inherent to the high versatility of their chemical composition, charge density, anion exchange capability, LDH-based materials are extensively studied and their performances for such applications are reported. Indeed the analytical characteristics (sensitivity and detection limit) of LDH-based electrodes are scrutinized, and their specific capacity or capacitance as electrode battery or supercapacitor materials, are detailed.

  5. Electrochemical DNA biosensor for detection of porcine oligonucleotides using ruthenium(II) complex as intercalator label redox

    Science.gov (United States)

    Halid, Nurul Izni Abdullah; Hasbullah, Siti Aishah; Ahmad, Haslina; Heng, Lee Yook; Karim, Nurul Huda Abd; Harun, Siti Norain

    2014-09-01

    A DNA biosensor detection of oligonucleotides via the interactions of porcine DNA with redox active complex based on the electrochemical transduction is described. A ruthenium(II) complex, [Ru(bpy)2(PIP)]2+, (bpy = 2,2'bipyridine, PIP = 2-phenylimidazo[4,5-f[[1,10-phenanthroline]) as DNA label has been synthesized and characterized by 1H NMR and mass spectra. The study was carried out by covalent bonding immobilization of porcine aminated DNA probes sequences on screen printed electrode (SPE) modified with succinimide-acrylic microspheres and [Ru(bpy)2(PIP)]2+ was used as electrochemical redox intercalator label to detect DNA hybridization event. Electrochemical detection was performed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) over the potential range where the ruthenium (II) complex was active. The results indicate that the interaction of [Ru(bpy)2(PIP)]2+ with hybridization complementary DNA has higher response compared to single-stranded and mismatch complementary DNA.

  6. Aluminium bismuthate nanorods and the electrochemical performance for detection of tartaric acid

    Energy Technology Data Exchange (ETDEWEB)

    Pei, L.Z., E-mail: lzpei@ahut.edu.cn [Key Lab of Materials Science and Processing of Anhui Province, School of Materials Science and Engineering, Anhui University of Technology, Ma' anshan, Anhui 243002 (China); Wei, T.; Lin, N.; Fan, C.G. [Key Lab of Materials Science and Processing of Anhui Province, School of Materials Science and Engineering, Anhui University of Technology, Ma' anshan, Anhui 243002 (China); Yang, Zao, E-mail: yangzao888@tom.com [National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, Sichuan 610064 (China)

    2016-09-15

    Aluminium bismuthate nanorods had been synthesized by a facile hydrothemral method. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations showed that the lengh and diameter were 2–10 μm and 50–200 nm, respectively. X-ray diffraction (XRD) and high-resolution TEM (HRTEM) showed that the nanorods were composed of single crystalline orthorhombic Al{sub 4}Bi{sub 2}O{sub 9} phase. The aluminium bismuthate nanorods could be explained by the nucleation and crystalline growth process based on the products obtained from different hydrothermal conditions. Aluminium bismuthate nanorods modified glassy carbon electrode (GCE) was fabricated for the electrochemical detection of tartaric acid (TA) in neutral solution. A pair of semi-reversible redox peaks located at −0.08 V and −0.53 V, respectively were observed. The current intensity of the cyclic voltammogram (CV) peak increased linearly obviously with increasing the scan rate and TA concentration. The detection limit and linear range were 0.64 μM and 0.001–2 mM, respectively with the correlation coefficient of 0.995. The aluminium bismuthate nanorods modified GCE had good reproducibility and stability for the detection of TA. - Highlights: • Aluminium bismuthate nanorods were synthesized by a facile hydrothermal process. • The size of aluminium bismuthate nanorods could be controlled by growth conditions. • Aluminium bismuthate nanorods showed good electrochemical performance for the detection of tartaric acid. • Aluminium bismuthate nanorods modified GCE had good reproducibility and stability.

  7. 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.

  8. Label-free electrochemical immunosensor based on cerium oxide nanowires for Vibrio cholerae O1 detection

    Energy Technology Data Exchange (ETDEWEB)

    Tam, Phuong Dinh, E-mail: phuongdinhtam@gmail.com; Thang, Cao Xuan, E-mail: thang.caoxuan@hust.edu.vn

    2016-01-01

    This paper developed a label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application. The CeO{sub 2} nanowires were synthesized by hydrothermal reaction. The immobilization of Anti-V. cholerae O1 onto CeO{sub 2} nanowire-deposited sensor was performed via an amino ester, which was created by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and sulfo-N-hydroxysuccinimide. The electrochemical responses of the immunosensor were studied by electrochemical impedance spectroscopy with [Fe (CN) {sub 6}] {sup 3−/4−} as redox probe. A linear response in electron transfer resistance for cell of V. cholerae O1 concentration was found in the range of 1.0 × 10{sup 2} CFU/mL to 1.0 × 10{sup 4} CFU/mL. The detection limit of the immunosensor was 1.0 × 10{sup 2} CFU/mL. The immunosensor sensitivity was 56.82 Ω/CFU·mL{sup −1}. Furthermore, the parameters affecting immunosensor response were also investigated, as follows: pH value, immunoreaction time, incubation temperature, and anti-V. cholerae O1 concentration. - Highlights: • A label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application was developed. • A linear response was found in the range of 1.0 × 10{sup 2} CFU/mL to 1.0 × 10{sup 4} CFU/mL. • The detection limit of the immunosensor was 1.0 × 10{sup 2} CFU/mL. • The immunosensor sensitivity was 56.82 Ω/CFU.mL{sup −1}.

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

    Science.gov (United States)

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

    2013-06-01

    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.

  10. Identification of pathogenic microbial cells and spores by electrochemical detection on a biochip

    Directory of Open Access Journals (Sweden)

    Andresen Heiko

    2004-04-01

    Full Text Available Abstract Background Bacillus cereus constitutes a significant cause of acute food poisoning in humans. Despite the recent development of different detection methods, new effective control measures and better diagnostic tools are required for quick and reliable detection of pathogenic micro-organisms. Thus, the objective of this study was to determine a simple method for rapid identification of enterotoxic Bacillus strains. Here, a special attention is given to an electrochemical biosensor since it meets the requirements of minimal size, lower costs and decreased power consumption. Results A bead-based sandwich hybridization system was employed in conjugation with electric chips for detection of vegetative cells and spores of Bacillus strains based on their toxin-encoding genes. The system consists of a silicon chip based potentiometric cell, and utilizes paramagnetic beads as solid carriers of the DNA probes. The specific signals from 20 amol of bacterial cell or spore DNA were achieved in less than 4 h. The method was also successful when applied directly to unpurified spore and cell extract samples. The assay for the haemolytic enterotoxin genes resulted in reproducible signals from B. cereus and B. thuringiensis while haemolysin-negative B. subtilis strain did not yield any signal. Conclusions The sensitivity, convenience and specificity of the system have shown its potential. In this respect an electrochemical detection on a chip enabling a fast characterization and monitoring of pathogens in food is of interest. This system can offer a contribution in the rapid identification of bacteria based on the presence of specific genes without preceding nucleic acid amplification.

  11. Detection of bar gene encoding phosphinothricin herbicide resistance in plants by electrochemical biosensor.

    Science.gov (United States)

    Ligaj, Marta; Tichoniuk, Mariusz; Filipiak, Marian

    2008-11-01

    An electrochemical biosensor for the detection of bar gene coding phosphinothricin herbicide resistance is presented. The detection was based on hybridization reaction between the specific to bar gene 19-mer probe immobilized on the electrode surface and complementary DNA in a sample. Single-stranded DNA probe specific to bar gene was covalently attached by 5'-phosphate end to the surface of carbon paste electrode. Outer layer of a conventional CPE was provided with carboxyl groups of stearic acid. ssDNA was coupled to the electrode through ethylenediamine with the use of water-soluble 1-ethyl-3(3'-dimethylaminopropyl)-carbodiimide and N-hydroxy-sulfosuccinimide as activating reagents. Hybridization reaction at the electrode surface was detected via Co(bpy)(3)(3+), which possess a much higher affinity to the resulting DNA duplex compared to ssDNA probe. Detection limit of the sensor was 0.1 microM of target DNA fragments and its response was linear from 5 to 20 microM. Hybridization event was also detected by measuring guanine peak but this approach presented distinctly higher detection limit (1 muM) and lower reproducibility. Complete time of one measurement with the use of the biosensor including covalent attachment of ethylenediamine (linker) and ssDNA probe to the electrode, hybridization with target and interaction with electroactive indicator was about 70 min.

  12. Zinc oxide/redox mediator composite films-based sensor for electrochemical detection of important biomolecules.

    Science.gov (United States)

    Tang, Chun-Fang; Kumar, S Ashok; Chen, Shen-Ming

    2008-09-15

    Electrochemical oxidation of serotonin (SN) onto zinc oxide (ZnO)-coated glassy carbon electrode (GCE) results in the generation of redox mediators (RMs) that are strongly adsorbed on electrode surface. The electrochemical properties of zinc oxide-electrogenerated redox mediator (ZnO/RM) (inorganic/organic) hybrid film-coated electrode has been studied using cyclic voltammetry (CV). The scanning electron microscope (SEM), atomic force microscope (AFM), and electrochemical techniques proved the immobilization of ZnO/RM core/shell microparticles on the electrode surface. The GCE modified with ZnO/RM hybrid film showed two reversible redox peaks in acidic solution, and the redox peaks were found to be pH dependent with slopes of -62 and -60 mV/pH, which are very close to the Nernst behavior. The GCE/ZnO/RM-modified electrode exhibited excellent electrocatalytic activity toward the oxidations of ascorbic acid (AA), dopamine (DA), and uric acid (UA) in 0.1M phosphate buffer solution (PBS, pH 7.0). Indeed, ZnO/RM-coated GCE separated the anodic oxidation waves of DA, AA, and UA with well-defined peak separations in their mixture solution. Consequently, the GCE/ZnO/RMs were used for simultaneous detection of DA, AA, and UA in their mixture solution. Using CV, calibration curves for DA, AA, and UA were obtained over the range of 6.0 x 10(-6) to 9.6 x 10(-4)M, 1.5 x 10(-5) to 2.4 x 10(-4)M, and 5.0 x 10(-5) to 8 x 10(-4)M with correlation coefficients of 0.992, 0.991, and 0.989, respectively. Moreover, ZnO/RM-modified GCE had good stability and antifouling properties.

  13. Toxicity detection of sodium nitrite, borax and aluminum potassium sulfate using electrochemical method

    Institute of Scientific and Technical Information of China (English)

    Dengbin Yu; Daming Yong; Shaojun Dong

    2013-01-01

    Based on the inhibition effect on the respiratory chain activity of microorganisms by toxicants,an electrochemical method has been developed to measure the current variation of a mediator in the presence of microorganisms contacted with a toxicant.Microelectrode arrays were adopted in this study,which can accelerate the mass transfer rate of an analyte to the electrode and also increase the total current signal,resulting in an improvement in detection sensitivity.We selected Escherichia coli as the testee and the standard glucoseglutamic acid as an exogenous material.Under oxygen restriction,the experiments in the presence of toxicant were performed at optimum conditions (solution pH 7.0,37℃ and reaction for 3 hr).The resulting solution was then separated from the suspended microorganisms and was measured by an electrochemical method,using ferricyanide as a mediator.The current signal obtained represents the re oxidation of ferrocyanide,which was transformed to inhibiting efficiency,IC50,as a quantitative measure of toxicity.The IC50 values measured were 410,570 and 830 mg/L for sodium nitrite,borax and aluminum potassium sulfate,respectively.The results show that the toxicity sequence for these three food additives is consistent with the value reported by other methods.Furthermore,the order of damage degree to the microorganism was also observed to be:sodium nitrite > borax > aluminum potassium sulfate >blank,according to the atomic force microscopy images of E.coli after being incubated for 3 hr with the toxic compound in buffer solutions.The electrochemical method is expected to be a sensitive and simple alternative to toxicity screening for chemical food additives.

  14. An integrated microfluidic analysis microsystems with bacterial capture enrichment and in-situ impedance detection

    Science.gov (United States)

    Liu, Hai-Tao; Wen, Zhi-Yu; Xu, Yi; Shang, Zheng-Guo; Peng, Jin-Lan; Tian, Peng

    2017-09-01

    In this paper, an integrated microfluidic analysis microsystems with bacterial capture enrichment and in-situ impedance detection was purposed based on microfluidic chips dielectrophoresis technique and electrochemical impedance detection principle. The microsystems include microfluidic chip, main control module, and drive and control module, and signal detection and processing modulet and result display unit. The main control module produce the work sequence of impedance detection system parts and achieve data communication functions, the drive and control circuit generate AC signal which amplitude and frequency adjustable, and it was applied on the foodborne pathogens impedance analysis microsystems to realize the capture enrichment and impedance detection. The signal detection and processing circuit translate the current signal into impendence of bacteria, and transfer to computer, the last detection result is displayed on the computer. The experiment sample was prepared by adding Escherichia coli standard sample into chicken sample solution, and the samples were tested on the dielectrophoresis chip capture enrichment and in-situ impedance detection microsystems with micro-array electrode microfluidic chips. The experiments show that the Escherichia coli detection limit of microsystems is 5 × 104 CFU/mL and the detection time is within 6 min in the optimization of voltage detection 10 V and detection frequency 500 KHz operating conditions. The integrated microfluidic analysis microsystems laid the solid foundation for rapid real-time in-situ detection of bacteria.

  15. Nitrogen-doped multiple graphene aerogel/gold nanostar as the electrochemical sensing platform for ultrasensitive detection of circulating free DNA in human serum.

    Science.gov (United States)

    Ruiyi, Li; Ling, Liu; Hongxia, Bei; Zaijun, Li

    2016-05-15

    Graphene aerogel has attracted increasing attention due to its large specific surface area, high-conductivity and electronic interaction. The paper reported a facile synthesis of nitrogen-doped multiple graphene aerogel/gold nanostar (termed as N-doped MGA/GNS) and its use as the electrochemical sensing platform for detection of double stranded (dsDNA). On the one hand, the N-doped MGA offers a much better electrochemical performance compared with classical graphene aerogel. Interestingly, the performance can be enhanced by only increasing the cycle number of graphene oxide gelation. On the other hand, the hybridization with GNS further enhances the electrocatalytic activity towards Fe(CN)6(3-/4-). In addition, the N-doped MGA/GNS provides a well-defined three-dimensional architecture. The unique structure make it is easy to combine with dsDNA to form the electroactive bioconjugate. The integration not only triggers an ultrafast DNA electron and charge transfer, but also realizes a significant synergy between N-doped MGA, GNS and dsDNA. As a result, the electrochemical sensor based on the hybrid exhibits highly sensitive differential pulse voltammetric response (DPV) towards dsDNA. The DPV signal linearly increases with the increase of dsDNA concentration in the range from 1.0×10(-)(21) g ml(-)(1) to 1.0×10(-16) g ml(-1) with the detection limit of 3.9×10(-22) g ml(-1) (S/N=3). The sensitivity is much more than that of all reported DNA sensors. The analytical method was successfully applied in the electrochemical detection of circulating free DNA in human serum. The study also opens a window on the electrical properties of multiple graphene aerogel and DNA as well their hybrids to meet the needs of further applications as special nanoelectronics in molecule diagnosis, bioanalysis and catalysis.

  16. Maximum Temperature Detection System for Integrated Circuits

    Science.gov (United States)

    Frankiewicz, Maciej; Kos, Andrzej

    2015-03-01

    The paper describes structure and measurement results of the system detecting present maximum temperature on the surface of an integrated circuit. The system consists of the set of proportional to absolute temperature sensors, temperature processing path and a digital part designed in VHDL. Analogue parts of the circuit where designed with full-custom technique. The system is a part of temperature-controlled oscillator circuit - a power management system based on dynamic frequency scaling method. The oscillator cooperates with microprocessor dedicated for thermal experiments. The whole system is implemented in UMC CMOS 0.18 μm (1.8 V) technology.

  17. Detection of hepatitis B virus DNA with a paper electrochemical sensor.

    Science.gov (United States)

    Li, Xiang; Scida, Karen; Crooks, Richard M

    2015-09-01

    Here we show that a simple paper-based electrochemical sensor, fabricated by paper folding, is able to detect a 30-base nucleotide sequence characteristic of DNA from the hepatitis B virus (HBV) with a detection limit of 85 pM. This device is based on design principles we have reported previously for detecting proteins via a metalloimmunoassay. It has four desirable attributes. First, its design combines simple origami (paper folding) assembly, the open structure of a hollow-channel paper analytical device to accommodate micrometer-scale particles, and a convenient slip layer for timing incubation steps. Second, two stages of amplification are achieved: silver nanoparticle labels provide a maximum amplification factor of 250 000 and magnetic microbeads, which are mobile solid-phase supports for the capture probes, are concentrated at a detection electrode and provide an additional ∼25-fold amplification. Third, there are no enzymes or antibodies used in the assay, thereby increasing its speed, stability, and robustness. Fourth, only a single sample incubation step is required before detection is initiated.

  18. Electrochemical detection of point mutation based on surface ligation reaction and biometallization.

    Science.gov (United States)

    Zhang, Peng; Chu, Xia; Xu, Xiangmin; Shen, Guoli; Yu, Ruqin

    2008-05-15

    A highly sensitive electrochemical method for point mutation detection based on surface enzymatic ligation reaction and biometallization is demonstrated. In this method the surface-immobilized allele-specific probe, complementary to the mutant target, undergoes allele-specific ligation with the 5'-phosphorylated ligation probe in the presence of the mutant oligonucleotide target and E. coli DNA ligase. If there is an allele mismatch, no ligation takes place. After thermal treatment at 90 degrees C, the formed duplex melts apart, which merely allows the ligation product to remain on the electrode surface. Then, biotinylated detection probes hybridize with the ligation product. With the binding of streptavidin-alkaline phosphatase (SA-ALP) to the biotinylated probes, a non-reductive substrate of alkaline phosphatase, ascorbic acid 2-phosphate (AA-P), can be converted into ascorbic acid (AA) at the electrode surface. Silver ions in solution are then reduced by AA, resulting in the deposition of silver metal onto the electrode surface. Linear sweep voltammetry (LSV) is used to detect the amount of deposited silver. The proposed approach has been successfully implemented for the identification of single base mutation in codon 12 of K-ras oncogene target with a detection limit of 80fM, demonstrating that this method provides a highly specific, sensitive and cost-efficient approach for point mutation detection.

  19. Molybdenum disulfide for ultra-low detection of free radicals: electrochemical response and molecular modeling

    Science.gov (United States)

    Gupta, Ankur; Rawal, Takat B.; Neal, Craig J.; Das, Soumen; Rahman, Talat S.; Seal, Sudipta

    2017-06-01

    Two-dimensional (2D) molybdenum disulfide (MoS2) offers attractive properties due to its band gap modulation and has led to significant research-oriented applications (i.e. DNA and protein detection, cell imaging (fluorescent label) etc.). In biology, detection of free radicals (i.e. reactive oxygen species and reactive nitrogen (NO*) species are very important for early discovery and treatment of diseases. Herein, for the first time, we demonstrate the ultra-low (pico-molar) detection of pharmaceutically relevant free radicals using MoS2 for electrochemical sensing. We present pico- to nano- molar level sensitivity in smaller MoS2 with S-deficiency as revealed by x-ray photoelectron spectroscopy. Furthermore, the detection mechanism and size-dependent sensitivity have been investigated by density functional theory (DFT) showing the change in electronic density of states of Mo atoms at edges which lead to the preferred adsorption of H2O2 on Mo edges. The DFT analysis signifies the role of size and S-deficiency in the higher catalytic activity of smaller MoS2 particles and, thus, ultra-low detection.

  20. Detection of parathyroid hormone using an electrochemical impedance biosensor based on PAMAM dendrimers.

    Science.gov (United States)

    Özcan, Hakkı Mevlüt; Sezgintürk, Mustafa Kemal

    2015-01-01

    This paper presents a novel hormone-based impedimetric biosensor to determine parathyroid hormone (PTH) level in serum for diagnosis and monitoring treatment of hyperparathyroidism, hypoparathyroidism and thyroid cancer. The interaction between PTH and the biosensor was investigated by an electrochemical method. The biosensor was based on the gold electrode modified by 12-mercapto dodecanoic (12MDDA). Antiparathyroid hormone (anti-PTH) was covalently immobilized on to poly amidoamine dendrimer (PAMAM) which was bound to a 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide/N-hydroxysuccinimide (EDC/NHS) couple, self-assembled monolayer structure from one of the other NH2 sites. The immobilization of anti-PTH was monitored by electrochemical impedance spectroscopy, cyclic voltammetry and scanning electron microscope techniques. After the optimization studies of immobilization materials such as 12MDDA, EDC-NHS, PAMAM, and glutaraldehyde, the performance of the biosensor was investigated in terms of linearity, sensitivity, repeatability, and reproducibility. PTH was detected within a linear range of 10-60 fg/mL. Finally the described biosensor was used to monitor PTH levels in artificial serum samples.

  1. Electrochemical detection of 17beta-estradiol using DNA aptamer immobilized gold electrode chip.

    Science.gov (United States)

    Kim, Yeon Seok; Jung, Ho Sup; Matsuura, Toshihiko; Lee, Hea Yeon; Kawai, Tomoji; Gu, Man Bock

    2007-05-15

    An electrochemical detection method for chemical sensing has been developed using a DNA aptamer immobilized gold electrode chip. DNA aptamers specifically binding to 17beta-estradiol were selected by the SELEX (Systematic Evolution of Ligands by EXponential enrichment) process from a random ssDNA library, composed of approximately 7.2 x 10(14) DNA molecules. Gold electrode chips were employed to evaluate the electrochemical signals generated from interactions between the aptamers and the target molecules. The DNA aptamer immobilization on the gold electrode was based on the avidin-biotin interaction. The cyclic voltametry (CV) and square wave voltametry (SWV) values were measured to evaluate the chemical binding to aptamer. When 17beta-estradiol interacted with the DNA aptamer, the current decreased due to the interference of bound 17beta-estradiol with the electron flow produced by a redox reaction between ferrocyanide and ferricyanide. In the negative control experiments, the current decreased only mildly due to the presence of other chemicals.

  2. Bare and boron-doped cubic silicon carbide nanowires for electrochemical detection of nitrite sensitively.

    Science.gov (United States)

    Yang, Tao; Zhang, Liqin; Hou, Xinmei; Chen, Junhong; Chou, Kuo-Chih

    2016-04-25

    Fabrication of eletrochemical sensors based on wide bandgap compound semiconductors has attracted increasing interest in recent years. Here we report for the first time electrochemical nitrite sensors based on cubic silicon carbide (SiC) nanowires (NWs) with smooth surface and boron-doped cubic SiC NWs with fin-like structure. Multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) were used to characterize SiC and boron-doped SiC NWs. As for the electrochemical behavior of both SiC NWs electrode, the cyclic voltammetric results show that both SiC electrodes exhibit wide potential window and excellent electrocatalytic activity toward nitrite oxidation. Differential pulse voltammetry (DPV) determination reveals that there exists a good linear relationship between the oxidation peak current and the concentration in the range of 50-15000 μmoL L(-1) (cubic SiC NWs) and 5-8000 μmoL L(-1) (B-doped cubic SiC NWs) with the detection limitation of 5 and 0.5 μmoL L(-1) respectively. Compared with previously reported results, both as-prepared nitrite sensors exhibit wider linear response range with comparable high sensitivity, high stability and reproducibility.

  3. Electrochemical detection of acetaminophen on the functionalized MWCNTs modified electrode using layer-by-layer technique

    Energy Technology Data Exchange (ETDEWEB)

    Manjunatha, Revanasiddappa [Chemistry Research Centre, S.S.M.R.V. Degree College, IV ' T' Block, Jayanagar, Bangalore 560041 (India); Nagaraju, Dodahalli Hanumantharayudu [Mechanical Engineering Department, National University of Singapore, 119615 (Singapore); Suresh, Gurukar Shivappa, E-mail: sureshssmrv@yahoo.co.in [Chemistry Research Centre, S.S.M.R.V. Degree College, IV ' T' Block, Jayanagar, Bangalore 560041 (India); Melo, Jose Savio; D' Souza, Stanislaus F. [Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Venkatesha, Thimmappa Venkatarangaiah [Department of Chemistry, Kuvempu University, Jnanasahyadri, Shimoga 577451 (India)

    2011-07-30

    A selective electrochemical method is fabricated via layer-by-layer (LBL) method using both positively and negatively charged multi walled carbon nanotubes (MWCNTs) on poly (diallyldimetheylammonium chloride) (PDDA)/poly styrene sulfonate (PSS) modified graphite electrode, for the determination of acetaminophen (ACT) in the presence of dopamine (DA) and high concentration of ascorbic acid (AA). The modified electrode was characterized by cyclic voltammetry (CV) electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Experimental conditions such as pH, accumulation potential and time, effect of potential sweep rates and interferents were studied. In CV well defined peaks for AA, ACT and DA are obtained at 24, 186 and 374 mV, respectively. The separations of peaks were 210, 188 and 398 mV between AA and DA, DA and ACT and AA and ACT, respectively. The diffusion coefficient was calculated by chronocoulometric. Chronoamperometric studies showed the linear relationship between oxidation peak current and concentration of ACT in the range 25-400 {mu}M (R = 0.9991). The detection limit was 5 x 10{sup -7} mol/L. The proposed method gave satisfactory results in the determination of ACT in pharmaceutical and human serum samples.

  4. Mismatch detection in DNA monolayers by atomic force microscopy and electrochemical impedance spectroscopy

    Directory of Open Access Journals (Sweden)

    Maryse D. Nkoua Ngavouka

    2016-02-01

    Full Text Available Background: DNA hybridization is at the basis of most current technologies for genotyping and sequencing, due to the unique properties of DNA base-pairing that guarantee a high grade of selectivity. Nonetheless the presence of single base mismatches or not perfectly matched sequences can affect the response of the devices and the major challenge is, nowadays, to distinguish a mismatch of a single base and, at the same time, unequivocally differentiate devices read-out of fully and partially matching sequences.Results: We present here two platforms based on different sensing strategies, to detect mismatched and/or perfectly matched complementary DNA strands hybridization into ssDNA oligonucleotide monolayers. The first platform exploits atomic force microscopy-based nanolithography to create ssDNA nano-arrays on gold surfaces. AFM topography measurements then monitor the variation of height of the nanostructures upon biorecognition and then follow annealing at different temperatures. This strategy allowed us to clearly detect the presence of mismatches. The second strategy exploits the change in capacitance at the interface between an ssDNA-functionalized gold electrode and the solution due to the hybridization process in a miniaturized electrochemical cell. Through electrochemical impedance spectroscopy measurements on extended ssDNA self-assembled monolayers we followed in real-time the variation of capacitance, being able to distinguish, through the difference in hybridization kinetics, not only the presence of single, double or triple mismatches in the complementary sequence, but also the position of the mismatched base pair with respect to the electrode surface.Conclusion: We demonstrate here two platforms based on different sensing strategies as sensitive and selective tools to discriminate mismatches. Our assays are ready for parallelization and can be used in the detection and quantification of single nucleotide mismatches in microRNAs or

  5. Nanomaterial-based Electrochemical Sensors for the Detection of Glucose and Cholesterol

    Science.gov (United States)

    Ahmadalinezhad, Asieh

    Electrochemical detection methods are highly attractive for the monitoring of glucose, cholesterol, cancer, infectious diseases, and biological warfare agents due to their low cost, high sensitivity, functionality despite sample turbidity, easy miniaturization via microfabrication, low power requirements, and a relatively simple control infrastructure. The development of implantable biosensors is laden with great challenges, which include longevity and inherent biocompatibility, coupled with the continuous monitoring of analytes. Deficiencies in any of these areas will necessitate their surgical replacement. In addition, random signals arising from non-specific adsorption events can cause problems in diagnostic assays. Hence, a great deal of effort has been devoted to the specific control of surface structures. Nanotechnology involves the creation and design of structures with at least one dimension that is below 100 nm. The optical, magnetic, and electrical properties of nanostructures may be manipulated by altering their size, shape, and composition. These attributes may facilitate improvements in biocompatibility, sensitivity and the specific attachment of biomaterials. Thus, the central theme of this dissertation pertains to highlighting the critical roles that are played by the morphology and intrinsic properties of nanomaterials when they are applied in the development of electrochemical biosensors. For this PhD project, we initially designed and fabricated a novel amperometric glucose biosensor based on the immobilization of glucose oxidase (GOx) on a Prussian blue modified nanoporous gold surface, which exhibited a rapid response and a low detection limit of 2.5 microM glucose. The sensitivity of the biosensor was found to be very high (177 microA/mM) and the apparent Michaelis--Menten constant was calculated to be 2.1 mM. Our study has demonstrated that nanoporous gold provides an excellent matrix for enzyme immobilization. To adopt these advanced

  6. Electrochemical Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Gang; Lin, Yuehe

    2008-07-20

    Sensitive and selective detection techniques are of crucial importance for capillary electrophoresis (CE), microfluidic chips, and other microfluidic systems. Electrochemical detectors have attracted considerable interest for microfluidic systems with features that include high sensitivity, inherent miniaturization of both the detection and control instrumentation, low cost and power demands, and high compatibility with microfabrication technology. The commonly used electrochemical detectors can be classified into three general modes: conductimetry, potentiometry, and amperometry.

  7. 电化学检测微全分析系统%Micro Total Analysis System with Electrochemical Detection

    Institute of Scientific and Technical Information of China (English)

    刘继锋; 曹卫东; 汪尔康

    2001-01-01

    介绍了安培、线性扫描、方波、吸附溶出伏安法、库仑法、电导和电势法、电化学发光、电化学传感器等电化学方法在微全分析系统(μ-TAS)中的应用,并指出了电化学检测微全分析系统的发展方向。%Electrochemistry offers a considerable promise for detection in micro total analysis system(μ-TAS). Such detection has remarkable sensitivity, tunable selectivity, and low-volume requirements. Due to the inherent miniaturization of electrochemical devices, low-power requirements, low cost and high compatibility with advanced micromachining and microfabrication technologies, electrochemical detection is most attractive for μ-TAS. Electrochemical detection methods, such as amperometric, linear-scan, square-wave, and adsorptive-stripping voltammetric, coulometric, conductivity, potentiometric, electrochemiluminecent detection and electrochemical sensor, have been widely used in μ-TAS.

  8. In-Channel-Grown Polypyrrole Nanowire for the Detection of DNA Hybridization in an Electrochemical Microfluidic Biosensor

    OpenAIRE

    2015-01-01

    A triple electrode setup with a Pt pseudo-reference electrode integrated in a polydimethylsiloxane- (PDMS-) based microchamber was designed and fabricated. The integrated electrodes were deposited onto SiO2/Si substrate by sputtering. The PDMS microchamber was patterned using an SU-8 mold and sealed with electrodes in oxygen plasma. Polypyrrole nanowires (PPy NWs) were electrochemically grown in situ at an accurate position of the working electrode in the sealed microchamber instead of in an ...

  9. Molecularly imprinted polymer based electrochemical detection of L-cysteine at carbon paste electrode.

    Science.gov (United States)

    Aswini, K K; Vinu Mohan, A M; Biju, V M

    2014-04-01

    A methacrylic acid (MAA) based molecularly imprinted polymer (MIP) modified carbon paste electrode (CPE) was developed for electrochemical detection of L-cysteine (Cys). Characterisation of MIP was done with FTIR and the modified electrode with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). CV, DPV and impedance analysis demonstrated that the modified electrode is responsive towards the target molecule. The optimum percentage composition of MIP for MIP/CPE and the effect of pH towards the electrode response for Cys were studied. The detection of Cys in the range of 2×10(-8) to 18×10(-8)M at MIP/CPE was monitored by DPV with a limit of detection of 9.6nM and R(2) of 0.9974. Also, various physiological interferents such as ascorbic acid, L-tryptophan, D-glucose, D-cysteine and L-cysteine were found to have little effect on DPV response at MIP/CPE. The utility of the electrode was proved by the effective detection of Cys from tap water and human blood plasma samples with reproducible results.

  10. Electrochemical Detection of Fluoroquinolone Antibiotics in Milk Using a Magneto Immunosensor

    Directory of Open Access Journals (Sweden)

    Daniel G. Pinacho

    2014-08-01

    Full Text Available An amperometric magneto-immunosensor (AMIS for the detection of residues of fluoroquinolone antibiotics in milk samples is described for the first time. The immunosensor presented combines magnetic beads biomodified with an antibody with a broad recognition profile of fluoroquinolones, a haptenized enzyme and a magnetic graphite–epoxy composite (m-GEC electrode. After the immunochemical reaction with specific enzyme tracer, the antibody biomodified magnetic beads are easily captured by an electrode made of graphite-epoxy composite containing a magnet, which also acts as transducer for the electrochemical detection. In spite of the complexity of milk, the use of magnetic beads allows elimination of potential interferences caused by the matrix components; hence the AMIS could perform quantitative measurements, directly in these samples, without any additional sample cleanup or extraction step. The immunosensor is able to detect up to seven different fluoroquinolones far below the MRLs defined by the UE for milk; for example ciprofloxacin is detected directly in milk with an IC50 of 0.74 µg/L and a LOD of 0.009 µg/L. This strategy offers great promise for rapid, simple, cost-effective, and on-site analysis fluoroquinolones in complex samples.

  11. Zepto-molar electrochemical detection of Brucella genome based on gold nanoribbons covered by gold nanoblooms

    Science.gov (United States)

    Rahi, Amid; Sattarahmady, Naghmeh; Heli, Hossein

    2015-12-01

    Gold nanoribbons covered by gold nanoblooms were sonoelectrodeposited on a polycrystalline gold surface at -1800 mV (vs. AgCl) with the assistance of ultrasound and co-occurrence of the hydrogen evolution reaction. The nanostructure, as a transducer, was utilized to immobilize a Brucella-specific probe and fabrication of a genosensor, and the process of immobilization and hybridization was detected by electrochemical methods, using methylene blue as a redox marker. The proposed method for detection of the complementary sequence, sequences with base-mismatched (one-, two- and three-base mismatches), and the sequence of non-complementary sequence was assayed. The fabricated genosensor was evaluated for the assay of the bacteria in the cultured and human samples without polymerase chain reactions (PCR). The genosensor could detect the complementary sequence with a calibration sensitivity of 0.40 μA dm3 mol-1, a linear concentration range of 10 zmol dm-3 to 10 pmol dm-3, and a detection limit of 1.71 zmol dm-3.

  12. Determination of Nicotine in Tobacco by Capillary Electrophoresis with Electrochemical Detection

    Institute of Scientific and Technical Information of China (English)

    SUN Jin-ying; XU Xiao-yu; YU Huan; YOU Tian-yan

    2012-01-01

    A sensitive,simple and low-cost method based on capillary electrophoresis(CE) with electrochemical(EC) detection at a carbon fiber microdisk electrode(CFE) was developed for the determination of nicotine.Effects of detection potential,concentration and pH value of the phosphate buffer,and injection time as well as separation voltage were investigated.Under the optimized conditions:a detection potential of 1.20 V,40 mmol/L phosphate buffer(pH 2.0),a sample injection time of 10 s at 10 kV and a separation voltage of 16 kV,the linear range obtained was from 5.0× 10 7 mol/L to 1.0× 10-4 mol/L with a correlation coefficient of 0.9989 and the limit of detection(LOD,S/N=3)obtained was 5.0× 10-8 mol/L.The method was also used to determine the nicotine in cigarettes.Nicotine amount ranged from 0.211 mg/g to 0.583 mg/g in the pipe tobacco of seven brands of cigarette and the amount in one cigarette varied from 0.136 mg/cigarette to 0.428 mg/cigarette.

  13. A Graphene and Aptamer Based Liquid Gated FET-Like Electrochemical Biosensor to Detect Adenosine Triphosphate.

    Science.gov (United States)

    Mukherjee, Souvik; Meshik, Xenia; Choi, Min; Farid, Sidra; Datta, Debopam; Lan, Yi; Poduri, Shripriya; Sarkar, Ketaki; Baterdene, Undarmaa; Huang, Ching-En; Wang, Yung Yu; Burke, Peter; Dutta, Mitra; Stroscio, Michael A

    2015-12-01

    Here we report successful demonstration of a FET-like electrochemical nano-biosensor to accurately detect ultralow concentrations of adenosine triphosphate. As a 2D material, graphene is a promising candidate due to its large surface area, biocompatibility, and demonstrated surface binding chemistries and has been employed as the conducting channel. A short 20-base DNA aptamer is used as the sensing element to ensure that the interaction between the analyte and the aptamer occurs within the Debye length of the electrolyte (PBS). Significant increase in the drain current with progressive addition of ATP is observed whereas for control experiments, no distinct change in the drain current occurs. The sensor is found to be highly sensitive in the nanomolar (nM) to micromolar ( μM) range with a high sensitivity of 2.55 μA (mM) (-1), a detection limit as low as 10 pM, and it has potential application in medical and biological settings to detect low traces of ATP. This simplistic design strategy can be further extended to efficiently detect a broad range of other target analytes.

  14. Synthesis, spectroscopic and electrochemical studies of phosphoryl and carbomethoxyphenyl substituted corroles, and their anion detection properties.

    Science.gov (United States)

    Yadav, Pinky; Sankar, Muniappan

    2014-10-21

    The synthesis, electrochemical studies and anion detection properties of triphosphoryl () and triester corroles () are reported and compared with triphenylcorrole (). These corroles exhibited typical acid-base binding behaviour in CH3CN and were converted to monoprotonated and dianionic species, respectively. has shown a ∼30 fold lower Keq value for monoprotonation than that of in a TFA-CH3CN medium. The detection ability of these corroles was also tested in acetonitrile towards various anions. The observed spectral changes in free-base corroles () are due to anion-induced deprotonation rather than the hydrogen bonding interaction between the imino protons of the corrole moiety with anions. and have shown higher equilibrium constants with F(-) ions (4.7 × 10(3) fold higher for and 9.7 × 10(3) fold higher for ) as compared to and are able to detect 0.06 μM of F(-) ions. The Cu(iii) and Ag(iii) complexes of and exhibited an anodic shift of ∼250 mV in first ring oxidation and ∼100-150 mV in metal centred reduction as compared to the Cu(iii) and Ag(iii) complexes of . The anodic shift in the redox potentials, lower protonation constants and lower detection limit of anions have been explained in terms of the electron-withdrawing nature of the diethylphosphite and carbomethoxy substituents at the meso-phenyl positions of the corrole ring.

  15. Electrochemical DNA sandwich biosensor based on enzyme amplified microRNA-21 detection and gold nanoparticles.

    Science.gov (United States)

    Mandli, Jihane; Mohammadi, Hasna; Amine, Aziz

    2017-08-01

    In this work, a novel electrochemical biosensor for miRNA-21 determination, involving a sandwich hybridization assay onto gold nanoparticles modified pencil graphite electrode (PGE) and enzyme signal amplification was reported. The thiol terminated capture probe 1 (SH-P1) was immobilized on the electrode through AuS interaction. In the presence of target miRNA-21, SH-P1 hybridized with the first part of the target, however, the second part hybridizes with a biotinylated probe P2 (B-P2). Then, a streptavidin-conjugated alkaline phosphatase was immobilized by a specific binding of avidin-B-P2. The enzyme catalyzed the electro-inactive α-naphtyl phosphate to an electro-active α-naphtol. The miRNA-21 detection was achieved through the changes of α-naphtol oxidation signals observed at +0.12V vs Ag/AgCl with Differential Pulse Voltammetry. Under the optimal detection conditions, the biosensor exhibited selective and sensitive detection with a linear range from 200pM to 388nM and the detection limit was 100pM (10fmol in 100μL). Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Electrochemical detection of fluoroquinolone antibiotics in milk using a magneto immunosensor.

    Science.gov (United States)

    Pinacho, Daniel G; Sánchez-Baeza, Francisco; Pividori, María-Isabel; Marco, María-Pilar

    2014-08-28

    An amperometric magneto-immunosensor (AMIS) for the detection of residues of fluoroquinolone antibiotics in milk samples is described for the first time. The immunosensor presented combines magnetic beads biomodified with an antibody with a broad recognition profile of fluoroquinolones, a haptenized enzyme and a magnetic graphite-epoxy composite (m-GEC) electrode. After the immunochemical reaction with specific enzyme tracer, the antibody biomodified magnetic beads are easily captured by an electrode made of graphite-epoxy composite containing a magnet, which also acts as transducer for the electrochemical detection. In spite of the complexity of milk, the use of magnetic beads allows elimination of potential interferences caused by the matrix components; hence the AMIS could perform quantitative measurements, directly in these samples, without any additional sample cleanup or extraction step. The immunosensor is able to detect up to seven different fluoroquinolones far below the MRLs defined by the UE for milk; for example ciprofloxacin is detected directly in milk with an IC50 of 0.74 µg/L and a LOD of 0.009 µg/L. This strategy offers great promise for rapid, simple, cost-effective, and on-site analysis fluoroquinolones in complex samples.

  17. Detection of Greenhouse Gas Precursors from Diesel Engines Using Electrochemical and Photoacoustic Sensors

    Directory of Open Access Journals (Sweden)

    Aline Rocha

    2010-11-01

    Full Text Available Atmospheric pollution is one of the worst threats to modern society. The consequences derived from different forms of atmospheric pollution vary from the local to the global scale, with deep impacts on climate, environment and human health. Several gaseous pollutants, even when present in trace concentrations, play a fundamental role in important processes that occur in atmosphere. Phenomena such as global warming, photochemical smog formation, acid rain and the depletion of the stratospheric ozone layer are strongly related to the increased concentration of certain gaseous species in the atmosphere. The transport sector significantly produces atmospheric pollution, mainly when diesel oil is used as fuel. Therefore, new methodologies based on selective and sensitive gas detection schemes must be developed in order to detect and monitor pollutant gases from this source. In this work, CO2 Laser Photoacoustic Spectroscopy was used to evaluate ethylene emissions and electrochemical analyzers were used to evaluate the emissions of CO, NOx and SO2 from the exhaust of diesel powered vehicles (rural diesel with 5% of biodiesel, in this paper called only diesel at different engine rotation speeds. Concentrations in the range 6 to 45 ppmV for ethylene, 109 to 1,231 ppmV for carbon monoxide, 75 to 868 ppmV for nitrogen oxides and 3 to 354 ppmV for sulfur dioxide were obtained. The results indicate that the detection techniques used were sufficiently selective and sensitive to detect the gaseous species mentioned above in the ppmV range.

  18. Rapid and sensitive measurements of nitrate ester explosives using microchip electrophoresis with electrochemical detection.

    Science.gov (United States)

    Piccin, Evandro; Dossi, Nicolò; Cagan, Avi; Carrilho, Emanuel; Wang, Joseph

    2009-03-01

    This article describes an effective microchip protocol based on electrophoretic-separation and electrochemical detection for highly sensitive and rapid measurements of nitrate ester explosives, including ethylene glycol dinitrate (EGDN), pentaerythritol tetranitrate (PETN), propylene glycol dinitrate (PGDN) and glyceryl trinitrate (nitroglycerin, NG). Factors influencing the separation and detection processes were examined and optimized. Under the optimal separation conditions obtained using a 15 mM borate buffer (pH 9.2) containing 20 mM SDS, and applying a separation voltage of 1500 V, the four nitrate ester explosives were separated within less than 3 min. The glassy-carbon amperometric detector (operated at -0.9 V vs. Ag/AgCl) offers convenient cathodic detection down to the picogram level, with detection limits of 0.5 ppm and 0.3 ppm for PGDN and for NG, respectively, along with good repeatability (RSD of 1.8-2.3%; n = 6) and linearity (over the 10-60 ppm range). Such effective microchip operation offers great promise for field screening of nitrate ester explosives and for supporting various counter-terrorism surveillance activities.

  19. Electrochemical impedance immunosensor for rapid detection of stressed pathogenic Staphylococcus aureus bacteria.

    Science.gov (United States)

    Bekir, Karima; Barhoumi, Houcine; Braiek, Mohamed; Chrouda, Amani; Zine, Nadia; Abid, Nabil; Maaref, Abdelrazek; Bakhrouf, Amina; Ouada, Hafedh Ben; Jaffrezic-Renault, Nicole; Mansour, Hedi Ben

    2015-10-01

    In this work, we report the adaptation of bacteria to stress conditions that induce instability of their cultural, morphological, and enzymatic characters, on which the identification of pathogenic bacteria is based. These can raise serious issues during the characterization of bacteria. The timely detection of pathogens is also a subject of great importance. For this reason, our objective is oriented towards developing an immunosensing system for rapid detection and quantification of Staphylococcus aureus. Polyclonal anti-S. aureus are immobilized onto modified gold electrode by self-assembled molecular monolayer (SAM) method. The electrochemical performances of the developed immunosensor were evaluated by impedance spectroscopy through the monitoring of the charge transfer resistance at the modified solid/liquid interface using ferri-/ferrocyanide as redox probe. The developed immunosensor was applied to detect stressed and resuscitate bacteria. As a result, a stable and reproducible immunosensor with sensitivity of 15 kΩ/decade and a detection limit of 10 CFU/mL was obtained for the S. aureus concentrations ranging from 10(1) to 10(7) CFU/mL. A low deviation in the immunosensor response (±10 %) was signed when it is exposed to stressed and not stressed bacteria.

  20. Modified Electrodes Used for Electrochemical Detection of Metal Ions in Environmental Analysis

    Directory of Open Access Journals (Sweden)

    Gregory March

    2015-04-01

    Full Text Available Heavy metal pollution is one of the most serious environmental problems, and regulations are becoming stricter. Many efforts have been made to develop sensors for monitoring heavy metals in the environment. This review aims at presenting the different label-free strategies used to develop electrochemical sensors for the detection of heavy metals such as lead, cadmium, mercury, arsenic etc. The first part of this review will be dedicated to stripping voltammetry techniques, on unmodified electrodes (mercury, bismuth or noble metals in the bulk form, or electrodes modified at their surface by nanoparticles, nanostructures (CNT, graphene or other innovative materials such as boron-doped diamond. The second part will be dedicated to chemically modified electrodes especially those with conducting polymers. The last part of this review will focus on bio-modified electrodes. Special attention will be paid to strategies using biomolecules (DNA, peptide or proteins, enzymes or whole cells.

  1. Ultrasensitive cDNA detection of dengue virus RNA using electrochemical nanoporous membrane-based biosensor.

    Directory of Open Access Journals (Sweden)

    Varun Rai

    Full Text Available A nanoporous alumina membrane-based ultrasensitive DNA biosensor is constructed using 5'-aminated DNA probes immobilized onto the alumina channel walls. Alumina nanoporous membrane-like structure is carved over platinum wire electrode of 76 µm diameter dimension by electrochemical anodization. The hybridization of complementary target DNA with probe DNA molecules attached inside the pores influences the pore size and ionic conductivity. The biosensor demonstrates linear range over 6 order of magnitude with ultrasensitive detection limit of 9.55×10(-12 M for the quantification of ss-31 mer DNA sequence. Its applicability is challenged against real time cDNA PCR sample of dengue virus serotype1 derived from asymmetric PCR. Excellent specificity down to one nucleotide mismatch in target DNA sample of DENV3 is also demonstrated.

  2. Determination of barnidipine in human serum and dog plasma by HPLC with electrochemical detection.

    Science.gov (United States)

    Takamura, K; Abdel-Wadood, H M; Kusu, F; Rafaat, I H; Saleh, G A; el-Rabbat, N A; Otagiri, M

    1995-10-01

    Barnidipine is a 1,4-dihydropyridine calcium antagonist. HPLC was conducted on a polybutadiene coated alumina column using an alkaline mobile phase and an electrochemical detector to determine the content of this drug in serum and plasma. A good linear relationship between barnidipine concentration and peak height was found in 5-500 ng/ml with a correlation coefficient of 0.998. The detection limit was 1 ng/ml. The within-day and day-to-day variations were examined for control human serum. Relative standard deviation of within-day assay for serum spiked with 10 ng/ml barnidipine.HCl was 6.9% and the recovery was 104%. A pharmacokinetic study was made in which the time course of barnidipine in dog plasma was followed.

  3. Measurement of serum pralidoxime methylsulfate (Contrathion) by high-performance liquid chromatography with electrochemical detection.

    Science.gov (United States)

    Houzé, Pascal; Borron, Stephen W; Scherninski, François; Bousquet, Bernard; Gourmel, Bernard; Baud, Frédéric

    2005-01-05

    Pralidoxime methylsulfate (Contrathion) is widely used to treat organophosphate poisoning. Despite animal and human studies, the usefulness of Contrathion therapy remains a matter of debate. Therapeutic dosage regimens need to be clarified and availability of a reliable method for plasma pralidoxime quantification would be helpful in this process. We here describe a high-performance liquid chromatography technique with electrochemical detection to measure pralidoxime concentrations in human serum using guanosine as an internal standard. The assay was linear between 0.25 and 50 microg mL(-1) with a quantification limit of 0.2 microg mL(-1). The analytical precision was satisfactory, with variation coefficients lower 10%. This assay was applied to the analysis of a serum from an organophosphorate poisoned patient and treated by Contrathion infusions (100 and 200 mg h(-1)) after a loading dose (400 mg).

  4. UV-nanoimprint lithography as a tool to develop flexible microfluidic devices for electrochemical detection.

    Science.gov (United States)

    Chen, Juhong; Zhou, Yiliang; Wang, Danhui; He, Fei; Rotello, Vincent M; Carter, Kenneth R; Watkins, James J; Nugen, Sam R

    2015-07-21

    Research in microfluidic biosensors has led to dramatic improvements in sensitivities. Very few examples of these devices have been commercially successful, keeping this methodology out of the hands of potential users. In this study, we developed a method to fabricate a flexible microfluidic device containing electrowetting valves and electrochemical transduction. The device was designed to be amenable to a roll-to-roll manufacturing system, allowing a low manufacturing cost. Microchannels with high fidelity were structured on a PET film using UV-NanoImprint Lithography (UV-NIL). The electrodes were inkjet-printed and photonically sintered on second flexible PET film. The film containing electrodes was bonded directly to the channel-containing layer to form sealed fluidic device. Actuation of the multivalve system with food dye in PBS buffer was performed to demonstrate automated fluid delivery. The device was then used to detect Salmonella in a liquid sample.

  5. Graphene Paper Decorated with a 2D Array of Dendritic Platinum Nanoparticles for Ultrasensitive Electrochemical Detection of Dopamine Secreted by Live Cells.

    Science.gov (United States)

    Zan, Xiaoli; Bai, Hongwei; Wang, Chenxu; Zhao, Faqiong; Duan, Hongwei

    2016-04-01

    To circumvent the bottlenecks of non-flexibility, low sensitivity, and narrow workable detection range of conventional biosensors for biological molecule detection (e.g., dopamine (DA) secreted by living cells), a new hybrid flexible electrochemical biosensor has been created by decorating closely packed dendritic Pt nanoparticles (NPs) on freestanding graphene paper. This innovative structural integration of ultrathin graphene paper and uniform 2D arrays of dendritic NPs by tailored wet chemical synthesis has been achieved by a modular strategy through a facile and delicately controlled oil-water interfacial assembly method, whereby the uniform distribution of catalytic dendritic NPs on the graphene paper is maximized. In this way, the performance is improved by several orders of magnitude. The developed hybrid electrode shows a high sensitivity of 2 μA cm(-2) μM(-1), up to about 33 times higher than those of conventional sensors, a low detection limit of 5 nM, and a wide linear range of 87 nM to 100 μM. These combined features enable the ultrasensitive detection of DA released from pheochromocytoma (PC 12) cells. The unique features of this flexible sensor can be attributed to the well-tailored uniform 2D array of dendritic Pt NPs and the modular electrode assembly at the oil-water interface. Its excellent performance holds much promise for the future development of optimized flexible electrochemical sensors for a diverse range of electroactive molecules to better serve society.

  6. Graphene Paper Decorated with a 2D Array of Dendritic Platinum Nanoparticles for Ultrasensitive Electrochemical Detection of Dopamine Secreted by Live Cells

    Science.gov (United States)

    Zan, Xiaoli; Wang, Chenxu

    2016-01-01

    Abstract To circumvent the bottlenecks of non‐flexibility, low sensitivity, and narrow workable detection range of conventional biosensors for biological molecule detection (e.g., dopamine (DA) secreted by living cells), a new hybrid flexible electrochemical biosensor has been created by decorating closely packed dendritic Pt nanoparticles (NPs) on freestanding graphene paper. This innovative structural integration of ultrathin graphene paper and uniform 2D arrays of dendritic NPs by tailored wet chemical synthesis has been achieved by a modular strategy through a facile and delicately controlled oil–water interfacial assembly method, whereby the uniform distribution of catalytic dendritic NPs on the graphene paper is maximized. In this way, the performance is improved by several orders of magnitude. The developed hybrid electrode shows a high sensitivity of 2 μA cm−2 μm −1, up to about 33 times higher than those of conventional sensors, a low detection limit of 5 nm, and a wide linear range of 87 nm to 100 μm. These combined features enable the ultrasensitive detection of DA released from pheochromocytoma (PC 12) cells. The unique features of this flexible sensor can be attributed to the well‐tailored uniform 2D array of dendritic Pt NPs and the modular electrode assembly at the oil–water interface. Its excellent performance holds much promise for the future development of optimized flexible electrochemical sensors for a diverse range of electroactive molecules to better serve society. PMID:26918612

  7. Analysis of nitroguanidine in Aqueous Solutions by HPLC (High Performance Liquid Chromatography) with electrochemical Detection and Voltammetry

    Science.gov (United States)

    1987-04-01

    The nitroguanidine was analyzed by high performance liquid chromatography (HPLC) with electrochemical detection at a hanging miercury drop electrode...previously reported on the application of solid sorbent collection techniques to the analysis of several explosives in water by high performance liquid chromatography (HPLC

  8. Electrochemical Detection of Alkaline Phosphatase in BALB/c Mouse Fetal Liver Stromal Cells with Capillary Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    Xue Mei SUN; Dong LI; Zeng Liang BAI; Wen Rui JIN

    2004-01-01

    A method for determination of alkaline phosphatase (ALP) in BALB/c mouse fetal liver stromal cells has been described based on the catalytic reaction. After the cell extract is incubated with the substrate disodium phenyl phosphate, the reaction product phenol generated by ALP is determined by capillary electrophoresis with electrochemical detection.

  9. Determination of Amino Acids in Single Human Lymphocytes after On-capillary Derivatization by Capillary Zone Electrophoresis with Electrochemical Detection

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Amino acids in individual human lymphocytes were determined by capillary zone electrophoresis with electrochemical detection after on-capillary derivatization. In order to inject cells easily, a cell injector was designed. Four amino acids (serine, alanine, taurine, and glycine) in single human lymphocytes have been identified. Quantitation has been accomplished through the use of calibration curves.

  10. Integration of paper-based microfluidic devices with commercial electrochemical readers

    OpenAIRE

    Whitesides, George M.; Nie, Zhihong; Deiss, Frédérique; Liu, Xinyu; Akbulut, Ozge

    2010-01-01

    The combination of simple Electrochemical Micro-Paper-based Analytical Devices (E\\(\\mu\\)PADs) with commercially available glucometers allows rapid, quantitative electrochemical analysis of a number of compounds relevant to human health (e.g., glucose, cholesterol, lactate, and alcohol) in blood or urine.

  11. Electrochemical Protein Cleavage in a Microfluidic Cell with Integrated Boron Doped Diamond Electrodes

    NARCIS (Netherlands)

    van den Brink, Floris T G; Zhang, Tao; Ma, Liwei; Bomer, Johan; Odijk, Mathieu; Olthuis, Wouter; Permentier, Hjalmar P; Bischoff, Rainer; van den Berg, Albert

    2016-01-01

    Specific electrochemical cleavage of peptide bonds at the C-terminal side of tyrosine and tryptophan generates peptides amenable to liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis for protein identification. To this end we developed a microfluidic electrochemical cell of 160 nL vo

  12. Electrochemical detection of commercial silver nanoparticles: identification, sizing and detection in environmental media

    Science.gov (United States)

    Stuart, E. J. E.; Tschulik, K.; Omanović, D.; Cullen, J. T.; Jurkschat, K.; Crossley, A.; Compton, R. G.

    2013-11-01

    The electrochemistry of silver nanoparticles contained in a consumer product has been studied. The redox properties of silver particles in a commercially available disinfectant cleaning spray were investigated via cyclic voltammetry before particle-impact voltammetry was used to detect single particles in both a typical aqueous electrolyte and authentic seawater media. We show that particle-impact voltammetry is a promising method for the detection of nanoparticles that have leached into the environment from consumer products, which is an important development for the determination of risks associated with the incorporation of nanotechnology into everyday products.

  13. Synthesis of Au/Graphene Oxide Composites for Selective and Sensitive Electrochemical Detection of Ascorbic Acid

    Science.gov (United States)

    Song, Jian; Xu, Lin; Xing, Ruiqing; Li, Qingling; Zhou, Chunyang; Liu, Dali; Song, Hongwei

    2014-12-01

    In this work, we present a novel ascorbic acid (AA) sensor applied to the detection of AA in human sera and pharmaceuticals. A series of Au nanoparticles (NPs) and graphene oxide sheets (Au NP/GO) composites were successfully synthesized by reduction of gold (III) using sodium citrate. Then the Au NP/GO composites were used to construct nonenzymatic electrodes in practical AA measurement. The electrode that has the best performance presents attractive analytical features, such as a low working potential of +0.15 V, a high sensitivity of 101.86 μA mM-1 cm-2 to AA, a low detection limit of 100 nM, good reproducibility and excellent selectivity. And more,it was also employed to accurately and practically detect AA in human serum and clinical vitamin C tablet with the existence of some food additive. The enhanced AA electrochemical properties of the Au NP/GO modified electrode in our work can be attributed to the improvement of electroactive surface area of Au NPs and the synergistic effect from the combination of Au NPs and GO sheets. This work shows that the Au NP/GO/GCEs hold the prospect for sensitive and selective determination of AA in practical clinical application.

  14. Electrochemical detection of aqueous Ag+ based on Ag+-assisted ligation reaction

    Science.gov (United States)

    Miao, Peng; Han, Kun; Wang, Bidou; Luo, Gangyin; Wang, Peng; Chen, Mingli; Tang, Yuguo

    2015-03-01

    In this work, a novel strategy to fabricate a highly sensitive and selective biosensor for the detection of Ag+ is proposed. Two DNA probes are designed and modified on a gold electrode surface by gold-sulfur chemistry and hybridization. In the presence of Ag+, cytosine-Ag+-cytosine composite forms and facilitates the ligation event on the electrode surface, which can block the release of electrochemical signals labeled on one of the two DNA probes during denaturation process. Ag+ can be sensitively detected with the detection limit of 0.1 nM, which is much lower than the toxicity level defined by U.S. Environmental Protection Agency. This biosensor can easily distinguish Ag+ from other interfering ions and the performances in real water samples are also satisfactory. Moreover, the two DNA probes are designed to contain the recognition sequences of a nicking endonuclease, and the ligated DNA can thus be cleaved at the original site. Therefore, the electrode can be regenerated, which allows the biosensor to be reused for additional tests.

  15. Dual detection of nitrate and mercury in water using disposable electrochemical sensors.

    Science.gov (United States)

    Bui, Minh-Phuong N; Brockgreitens, John; Ahmed, Snober; Abbas, Abdennour

    2016-11-15

    Here we report a disposable, cost effective electrochemical paper-based sensor for the detection of both nitrate and mercury ions in lake water and contaminated agricultural runoff. Disposable carbon paper electrodes were functionalized with selenium particles (SePs) and gold nanoparticles (AuNPs). The AuNPs served as a catalyst for the reduction of nitrate ions using differential pulse voltammetry techniques. The AuNPs also served as a nucleation sites for mercury ions. The SePs further reinforced this mercury ion nucleation due to their high binding affinity to mercury. Differential pulse stripping voltammetry techniques were used to further enhance mercury ion accumulation on the modified electrode. The fabricated electrode was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electrochemistry techniques. The obtained results show that the PEG-SH/SePs/AuNPs modified carbon paper electrode has a dual functionality in that it can detect both nitrate and mercury ions without any interference. The modified carbon paper electrode has improved the analytical sensitivity of nitrate and mercury ions with limits of detection of 8.6µM and 1.0ppb, respectively. Finally, the modified electrode was used to measure nitrate and mercury in lake water samples.

  16. Development of an Electrochemical Biosensor for the Detection of Aflatoxin M1 in Milk

    Directory of Open Access Journals (Sweden)

    Jean-Louis Marty

    2010-10-01

    Full Text Available We have developed an electrochemical immunosensor for the detection of ultratrace amounts of aflatoxin M1 (AFM1 in food products. The sensor was based on a competitive immunoassay using horseradish peroxidase (HRP as a tag. Magnetic nanoparticles coated with antibody (anti-AFM1 were used to separate the bound and unbound fractions. The samples containing AFM1 were incubated with a fixed amount of antibody and tracer [AFM1 linked to HRP (conjugate] until the system reached equilibrium. Competition occurs between the antigen (AFM1 and the conjugate for the antibody. Then, the mixture was deposited on the surface of screen-printed carbon electrodes, and the mediator [5-methylphenazinium methyl sulphate (MPMS] was added. The enzymatic response was measured amperometrically. A standard range (0, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.3, 0.4 and 0.5 ppb of AFM1-contaminated milk from the ELISA kit was used to obtain a standard curve for AFM1. To test the detection sensitivity of our sensor, samples of commercial milk were supplemented at 0.01, 0.025, 0.05 or 0.1 ppb with AFM1. Our immunosensor has a low detection limit (0.01 ppb, which is under the recommended level of AFM1 [0.05 µg L-1 (ppb], and has good reproducibility.

  17. A sensitive, label-free electrochemical detection of telomerase activity without modification or immobilization.

    Science.gov (United States)

    Liu, Xu; Wei, Min; Xu, Ensheng; Yang, Haitang; Wei, Wei; Zhang, Yuanjian; Liu, Songqin

    2017-05-15

    Telomerase has become one of the most typical tumor marker because it is closely related to cancers. In this paper, a simple label-free electrochemical detection of telomerase activity by using methylene blue (MB) as a G-quadruplex binding probe was proposed, avoiding commonly used complex label procedures, nano-probe synthesis, complicated electrode modification, probe immobilization or signal amplification. In the presence of telomerase substrate (TS) primer, the binding of MB on primer was weak. When repeats of (TTAGGG) were extended on the TS primer under the action of telomerase, they formed multiple G-quadruplexes with the help of K(+). As a result, a large amount of MB bounded to multiple G-quadruplexes because they have more strong interaction with G-quadruplexes than TS primer. As a result, the diffusion current of MB decreased sharply, which was strongly dependent on the telomerase activity. The DPV current change has a linear correlation with the logarithm of HeLa cell number in the range of 10-10,000 cells, with the detection limit of 3 cells. The high sensitivity was due to the formed multiple G-quadruplexes. Using indium tin oxide (ITO) as working electrode without modification ensured the good reproducibility of the method. The method was also simple, rapid, and has been successfully applied in the telomerase activity detection in urine with good selectivity and reproducibility, which is significant for cancer diagnosis, anticancer drugs screening, and cancer therapy evaluation.

  18. Simultaneous determination of quinolones for veterinary use by high-performance liquid chromatography with electrochemical detection.

    Science.gov (United States)

    Rodríguez Cáceres, M I; Guiberteau Cabanillas, A; Galeano Díaz, T; Martínez Cañas, M A

    2010-02-01

    A selective method based on high-performance liquid chromatography with electrochemical detection (HPLC-ECD) has been developed to enable simultaneous determination of three fluoroquinolones (FQs), namely danofloxacin (DANO), difloxacin (DIFLO) and sarafloxacin (SARA). The fluoroquinolones are separated on a Novapack C-18 column and detected in a high sensitivity amperometric cell at a potential of +0.8 V. Solid-phase extraction was used for the extraction of the analytes in real samples. The range of concentration examined varied from 10 to 150 ng g(-1) for danofloxacin, from 25 to 100 ng g(-1) for sarafloxacin and from 50 to 315 ng g(-1) for difloxacin, respectively. The method presents detection limits under 10 ng g(-1) and recoveries around 90% for the three analytes have been obtained in the experiments with fortified samples. This HPLC-ECD approach can be useful in the routine analysis of antibacterial residues being less expensive and less complicated than other more powerful tools as hyphenated techniques.

  19. An Electrochemical Detection of Metallothioneins at the Zeptomole Level in Nanolitre Volumes

    Directory of Open Access Journals (Sweden)

    Rene Kizek

    2008-04-01

    Full Text Available An Electrochemical Detection of Metallothioneins at the Zeptomole Level in Nanolitre VolumesWe report on improvement of the adsorptive transfer stripping technique (AdTS coupled with the differential pulse voltammetry Brdicka reaction to determine a thiol-protein. The current technique has been unable to generate reproducible results when analyzing very low sample volumes (nanolitres. This obstacle can be overcome technically by modifying the current transfer technique including cooling step of the adsorbed analyte. We tested the technique on determination of a promising tumour disease marker protein called metallothionein (MT. The detection limit (3 S/N of MT was evaluated as 500 zeptomoles per 500 nL (1 pM and the quantification limit (10 S/N as 1,500 zeptomoles per 500 nL (3 pM. Further, the improved AdTS technique was utilized to analyze blood serum samples from patients with breast cancer. Based on the results obtained it can be concluded that the improved technique can be used to detect a thiolprotein in very low sample volumes and can also prevent interferences during the washing and transferring step.

  20. A superstructure-based electrochemical assay for signal-amplified detection of DNA methyltransferase activity.

    Science.gov (United States)

    Zhang, Hui; Yang, Yin; Dong, Huilei; Cai, Chenxin

    2016-12-15

    DNA methyltransferase (MTase) activity is highly correlated with the occurrence and development of cancer. This work reports a superstructure-based electrochemical assay for signal-amplified detection of DNA MTase activity using M.SssI as an example. First, low-density coverage of DNA duplexes on the surface of the gold electrode was achieved by immobilized mercaptohexanol, followed by immobilization of DNA duplexes. The duplex can be cleaved by BstUI endonuclease in the absence of DNA superstructures. However, the cleavage is blocked after the DNA is methylated by M.SssI. The DNA superstructures are formed with the addition of helper DNA. By using an electroactive complex, RuHex, which can bind to DNA double strands, the activity of M.SssI can be quantitatively detected by differential pulse voltammetry. Due to the high site-specific cleavage by BstUI and signal amplification by the DNA superstructure, the biosensor can achieve ultrasensitive detection of DNA MTase activity down to 0.025U/mL. The method can be used for evaluation and screening of the inhibitors of MTase, and thus has potential in the discovery of methylation-related anticancer drugs.

  1. Quality Analysis of Herbal Medicine Products Prepared from Herba Sarcandrae by Capillary Electrophoresis with Electrochemical Detection

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xiao-guang; SUN Jin-ying; ZHU De-rong; YUAN Bai-qing; YOU Tian-yan

    2008-01-01

    A capillary electrophoresis with electrochemical detection(CE-ED)method was developed for the quality analysis of herbal medicine products prepared from the sanle herb of Herba Sarcandrae:Fufang Caoshanhu tablets,Qingrexiaoyanning capsules,and Xuekang oral liquids.Under the optimal analysis conditions,the low detection limit[1.0×10-7mol/L(S/N=3)]and the wide linear range(1.0×10-7-1.0×10-4 mol/L)were obtained for quality standard compound of isofraxidin.The precisions of the peak current and the migration time(as RSDs)for the real sample analysis were 2.0%-2.6%,and 1.2%-1.8%for isofraxidin,respectively.The contents of isofraxidin detected were 15.77 μg/tablet,0.48 mg/capsule,1.2 mg/ampoule(Jiangxi),and 0.44 mg/ampoule(Dalian)for Fufang Canshanhu tablets,Qingrexiao yanning capsules,and Xuekang oral liquids from different manufacturers,respectively.Quality estimate Was conducted by comparing the contents of isofraxidin in the herbal medicine products with the demanded values of Chinese pharmacopeia.In addition,based on their own unique CE-ED profiles(namely,CE-ED electropherograrns)the Xuekang oral liquids from the different manufacturers could be easily identified.

  2. Determination of textile dyes by means of non-aqueous capillary electrophoresis with electrochemical detection.

    Science.gov (United States)

    Peláez-Cid, Alejandra-Alicia; Blasco-Sancho, Sonia; Matysik, Frank-Michael

    2008-06-15

    Eight textile dye compounds including five cationic dyes, namely, basic blue 41, basic blue 9, basic green 4, basic violet 16 and basic violet 3, and three anionic dyes, acid green 25, acid red 1 and acid blue 324, were separated and detected by non-aqueous capillary electrophoresis (NACE) with electrochemical detection. Simultaneous separations of acid and basic dyes were performed using an acetonitrile-based buffer. Particular attention was paid to the determination of basic textile dyes. The optimized electrophoresis buffer for the separation of basic dyes was a solvent mixture of acetonitrile/methanol (75:25, v/v) containing 1 M acetic acid and 10 mM sodium acetate. The limits of detection for the basic dyes were in the range of 0.1-0.7 microg mL(-1). An appropriate solid-phase extraction procedure was developed for the pre-treatment of aqueous samples with different matrices. This analytical approach was successfully applied to various water samples including river and lake water which were spiked with textile dyes.

  3. A portable electrochemical magnetoimmunosensor for detection of sulfonamide antimicrobials in honey.

    Science.gov (United States)

    Muriano, A; Pinacho, D-G; Chabottaux, V; Diserens, J-M; Granier, B; Stead, S; Sanchez Baeza, F; Pividori, M I; Marco, M-P

    2013-09-01

    A new electrochemical magnetoimmunosensor (EMIS) has been developed for the screening of residues of sulfonamide antimicrobials in honey samples. The immunosensor is able to detect up to ten different sulfonamide congeners at levels below the action points established in some European countries (25 μg kg(-1)) after a hydrolysis step in which the sulfonamides are released from the corresponding conjugates formed in samples of this type. In spite of the complexity of the sample after the hydrolysis procedure, the EMIS could perform quantitative measurements, directly in these samples, without any additional sample cleanup or extraction step. For example, sulfapyridine, used as a reference, can be detected in hydrolyzed honey with a limit of detection (IC90) of 0.1 ± 0.03 μg kg(-1). Considering that the use of antibiotics for bee treatment is prohibited in the European Union, the immunosensor presented here could be an excellent screening tool. Moreover, several samples can be processed in parallel, which facilitates the analysis, reducing the necessity to use more costly confirmatory methods for just screening. As a proof of concept, a set of blind honey samples (spiked and incurred) were analyzed and the results were compared with those obtained by high-performance liquid chromatography-tandem mass spectrometry, demonstrating the potential of the EMIS as a screening tool.

  4. Generation of Small Single Domain Nanobody Binders for Sensitive Detection of Testosterone by Electrochemical Impedance Spectroscopy.

    Science.gov (United States)

    Li, Guanghui; Zhu, Min; Ma, Lu; Yan, Junrong; Lu, Xiaoling; Shen, Yanfei; Wan, Yakun

    2016-06-01

    A phage display library of variable domain of the heavy chain only antibody or nanobody (Nb) was constructed after immunizing a bactrian camel with testosterone. With the smaller molecular size (15 kDa), improved solubility, good stability, high affinity, specificity, and lower immunogenicity, Nbs are a promising tool in the next generation of diagnosis and medical applications. Testosterone is a reproductive hormone, playing an important role in normal cardiac function and being the highly predictive marker for many diseases. Herein, a simple and sensitive immunosensor based on electrochemical impedance spectroscopy (EIS) and Nbs was successfully developed for the determination of testosterone. We successfully isolated the antitestosterone Nbs from an immune phage display library. Moreover, one of the Nbs was biotinylated according to in vivo BirA system, which showed the highest production yield and the most stable case. Further, the EIS immunosensor was set up for testosterone detection by applying the biotinylated antitestosterone Nb. As a result, the biosensor exhibited a linear working range from 0.05 to 5 ng mL(-1) with a detection limit of 0.045 ng mL(-1). In addition, the proposed immunosensor was successfully applied in determining testosterone in serum samples. In conclusion, the proposed immunosensor revealed high specificity of testosterone detection and showed as a potential approach for sensitive and accurate diagnosis of testosterone.

  5. An integrated control and readout circuit for implantable multi-target electrochemical biosensing.

    Science.gov (United States)

    Ghoreishizadeh, Sara S; Baj-Rossi, Camilla; Cavallini, Andrea; Carrara, Sandro; De Micheli, Giovanni

    2014-12-01

    We describe an integrated biosensor capable of sensing multiple molecular targets using both cyclic voltammetry (CV) and chronoamperometry (CA). In particular, we present our custom IC to realize voltage control and current readout of the biosensors. A mixed-signal circuit block generates sub-Hertz triangular waveform for the biosensors by means of a direct-digital-synthesizer to control CV. A current to pulse-width converter is realized to output the data for CA measurement. The IC is fabricated in 0.18 μm technology. It consumes 220 μW from 1.8 V supply voltage, making it suitable for remotely-powered applications. Electrical measurements show excellent linearity in sub- μA current range. Electrochemical measurements including CA measurements of glucose and lactate and CV measurements of the anti-cancer drug Etoposide have been acquired with the fabricated IC and compared with a commercial equipment. The results obtained with the fabricated IC are in good agreement with those of the commercial equipment for both CV and CA measurements.

  6. Integrated Electrochemical Processes for CO2 Capture and Conversion to Commodity Chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Hatton, T. Alan [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Jamison, Timothy [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2013-09-30

    The Massachusetts Institute of Technology (MIT) and Siemens Corporations (SCR) are developing new chemical synthesis processes for commodity chemicals from CO2. The process is assessed as a novel chemical sequestration technology that utilizes CO2 from dilute gas streams generated at industrial carbon emitters as a raw material to produce useful commodity chemicals. Work at Massachusetts Institute of Technology (MIT) commenced on October 1st, 2010, and finished on September 30th, 2013. During this period, we have investigated and accomplished five objectives that mainly focused on converting CO2 into high-value chemicals: 1) Electrochemical assessment of catalytic transformation of CO2 and epoxides to cyclic carbonates; 2) Investigation of organocatalytic routes to convert CO2 and epoxide to cyclic carbonates; 3) Investigation of CO2 Capture and conversion using simple olefins under continuous flow; 4) Microwave assisted synthesis of cyclic carbonates from olefins using sodium bicarbonates in a green pathway; 5) Life cycle analyses of integrated chemical sequestration process. In this final report, we will describe the detailed study performed during the three year period and findings and conclusions drawn from our research.

  7. Highly Sensitive Bacteria Quantification Using Immunomagnetic Separation and Electrochemical Detection of Guanine-Labeled Secondary Beads

    Directory of Open Access Journals (Sweden)

    Harikrishnan Jayamohan

    2015-05-01

    Full Text Available In this paper, we report the ultra-sensitive indirect electrochemical detection of E. coli O157:H7 using antibody functionalized primary (magnetic beads for capture and polyguanine (polyG oligonucleotide functionalized secondary (polystyrene beads as an electrochemical tag. Vacuum filtration in combination with E. coli O157:H7 specific antibody modified magnetic beads were used for extraction of E. coli O157:H7 from 100 mL samples. The magnetic bead conjugated E. coli O157:H7 cells were then attached to polyG functionalized secondary beads to form a sandwich complex (magnetic bead/E. coli secondary bead. While the use of magnetic beads for immuno-based capture is well characterized, the use of oligonucleotide functionalized secondary beads helps combine amplification and potential multiplexing into the system. The antibody functionalized secondary beads can be easily modified with a different antibody to detect other pathogens from the same sample and enable potential multiplexing. The polyGs on the secondary beads enable signal amplification up to 10\\(^{8}\\ guanine tags per secondary bead (\\(7.5\\times10^{6}\\ biotin-FITC per secondary bead, 20 guanines per oligonucleotide bound to the target (E. coli. A single-stranded DNA probe functionalized reduced graphene oxide modified glassy carbon electrode was used to bind the polyGs on the secondary beads. Fluorescent imaging was performed to confirm the hybridization of the complex to the electrode surface. Differential pulse voltammetry (DPV was used to quantify the amount of polyG involved in the hybridization event with tris(2,2'-bipyridineruthenium(II (Ru(bpy\\(_{3}^{2+}\\ as the mediator. The amount of polyG signal can be correlated to the amount of E. coli O157:H7 in the sample. The method was able to detect concentrations of E. coli O157:H7 down to 3 CFU/100 mL, which is 67 times lower than the most sensitive technique reported in literature. The signal to noise ratio for this work was 3

  8. Micro and nanoscale electrochemical systems for reagent generation, coupled electrokinetic transport and enhanced detection

    Science.gov (United States)

    Contento, Nicholas M.

    Chemical analysis is being performed in devices operated at ever decreasing length scales in order to harness the fundamental benefits of micro and nanoscale phenomena while minimizing operating footprint and sample size. The advantages of moving traditional sample or chemical processing steps (e.g. separation, detection, and reaction) into micro- and nanofluidic devices have been demonstrated, and they arise from the relatively rapid rates of heat and mass transport at small length scales. The use of electrochemical methods in micro/nanoscale systems to control and improve these processes holds great promise. Unfortunately, much is still not understood about the coupling of multiple electrode driven processes in a confined environment nor about the fundamental changes in device performance that occur as geometries approach the nanoscale regime. At the nanoscale a significant fraction of the sample volume is in close contact with the device surface, i.e. most of the sample is contained within electronic or diffusion layers associated with surface charge or surface reactions, respectively. The work presented in this thesis aims to understand some fundamental different behaviors observed in micro/nanofluidic structures, particularly those containing one or more embedded, metallic electrode structures. First, a quantitative method is devised to describe the impact of electric fields on electrochemistry in multi-electrode micro/nanofluidic systems. Next the chemical manipulation of small volumes (≤ 10-13 L) in micro/nanofluidic structures is explored by creating regions of high pH and high dissolved gas (H 2) concentration through the electrolysis of H2O. Massively parallel arrays of nanochannel electrodes, or embedded annular nanoband electrodes (EANEs), are then studied with a focus on achieving enhanced signals due to coupled electrokinetic and electrochemical effects. In EANE devices, electroosmotic flow results from the electric field generated between the

  9. Construction and application of electrochemical sensors for the detection of naphthol

    Directory of Open Access Journals (Sweden)

    Jujie REN

    2016-02-01

    Full Text Available A poly(L-cysteine/graphene oxide composite modified glassy carbon naphthol electrode is constructed, which is used for simultaneous determination of 1-naphthol (1-NAP and 2-naphthol (2-NAP. The electrochemical behavior of 1-NAP and 2-NAP on the modified electrode are investigated by cyclic voltammetry (CV and differential pulse voltammetry (DPV, and the conditions to modify the electrode and to detect naphthol isomers are optimized. The results show that the modified electrode has an excellent electrocatalytic activity in the oxidation of the naphthol in phosphate buffered solution of 0.1 mol/L PBS (pH 7.5. The difference of oxidation peak potential between 1-naphthol and 2-naphthol could reach 0182 V, which is almost large enough to achieve the simultaneous detection for 1-naphthol and 2-naphthol in a mixture solution. Under optimized experimental conditions, differential pulse voltammetry is adopted to detect naphthol isomer. It is found that the oxidation peak currents of 1-NAP and 2-NAP show a good linear relationship with the concentration in the range of 2~40 μmol/L and 1~40 μmol/L, respectively. The detection limits (S/N=3 for 1-NAP and 2-NAP are 0.19 μmol/L and 0.12 μmol/L, respectively. The modified electrode shows good stability and reproducibility and has strong anti-interference ability in the detection. The electrode is applied to determine 1-NAP and 2-NAP in real water samples, and the average recoveries are in the range of 98.9% to 101.7% and 97.7% to 102.1%, respectively.

  10. Rapid Electrochemical Detection and Identification of Microbiological and Chemical Contaminants for Manned Spaceflight Project

    Science.gov (United States)

    Pierson, Duane; Botkin, Douglas; Gazda, Daniel

    2014-01-01

    Microbial control in the spacecraft environment is a daunting task, especially in the presence of human crew members. Currently, assessing the potential crew health risk associated with a microbial contamination event requires return of representative environmental samples that are analyzed in a ground-based laboratory. It is therefore not currently possible to quickly identify microbes during spaceflight. This project addresses the unmet need for spaceflight-compatible microbial identification technology. The electrochemical detection and identification platform is expected to provide a sensitive, specific, and rapid sample-to-answer capability for in-flight microbial monitoring that can distinguish between related microorganisms (pathogens and non-pathogens) as well as chemical contaminants. This will dramatically enhance our ability to monitor the spacecraft environment and the health risk to the crew. Further, the project is expected to eliminate the need for sample return while significantly reducing crew time required for detection of multiple targets. Initial work will focus on the optimization of bacterial detection and identification. The platform is designed to release nucleic acids (DNA and RNA) from microorganisms without the use of harmful chemicals. Bacterial DNA or RNA is captured by bacteria-specific probe molecules that are bound to a microelectrode, and that capture event can generate a small change in the electrical current (Lam, et al. 2012. Anal. Chem. 84(1): 21-5.). This current is measured, and a determination is made whether a given microbe is present in the sample analyzed. Chemical detection can be accomplished by directly applying a sample to the microelectrode and measuring the resulting current change. This rapid microbial and chemical detection device is designed to be a low-cost, low-power platform anticipated to be operated independently of an external power source, characteristics optimal for manned spaceflight and areas where power

  11. Selective Electrochemical Detection of Ciprofloxacin with a Porous Nafion/Multiwalled Carbon Nanotube Composite Film Electrode.

    Science.gov (United States)

    Gayen, Pralay; Chaplin, Brian P

    2016-01-27

    This study focuses on the development of electrochemical sensors for the detection of Ciprofloxacin (CFX) in natural waters and wastewater effluents. The sensors are prepared by depositing a layer of multiwalled carbon nanotubes (MWCNTs) dispersed in a porous Nafion film on to a boron-doped diamond (BDD) electrode substrate. The porous-Nafion-MWCNT/BDD electrode enhanced detection of CFX due to selective adsorption, which was accomplished by a combination of electrostatic attraction at -SO3(-) sites in the porous Nafion film and the formation of charge assisted hydrogen bonding between CFX and -COOH MWCNT surface functional groups. By contrast, the bare BDD electrode did not show any activity for CFX oxidation. The sensors were selective for CFX detection in the presence of other antibiotics (i.e., amoxicillin) and other nontarget water constituents (i.e., Cl(-), Ca(2+), humic acid, sodium dodecylbenzenesulfonate, salicylic acid, 4-aminobenzoic acid, and 4-hydroxybenzoic acid). A limit of detection of 5 nM (S/N = 5.04 ± 0.26) in a 0.1 M KH2PO4 supporting electrolyte (pH = 4.5) was obtained using differential pulse voltammetry. The linear dynamic ranges with respect to CFX concentration were 0.005-0.05 μM and 0.05-10 μM, and the sensitivities were 41 ± 5.2 μA μM(-1) and 2.1 ± 0.22 μA μM(-1), respectively. Sensor fouling was observed at high concentrations of some organic compounds such as 1 mM 4-aminobenzoic acid and 4-hydroxybenzoic acid. However, a short cathodic treatment fully restores sensor response. The results indicate that these sensors have application in detecting CFX in natural waters and wastewater effluents.

  12. Electrochemical enzyme biosensors based on calcium phosphate materials for tyramine detection in food samples.

    Science.gov (United States)

    Sánchez-Paniagua López, Marta; Redondo-Gómez, Esther; López-Ruiz, Beatriz

    2017-12-01

    Electrochemical tyrosinase biosensors for tyramine determination were developed by the immobilization of the enzyme in calcium phosphate materials (CaPs) followed by cross-linking with glutaraldehyde. Tyramine was detected by the electrochemical reduction at -0.1V of the o- enzymatically-formed dopaquinone. Three different CaPs were explored as immobilization systems, monetite, brushite and brushite cement. Biosensors based on brushite matrices provide better analytical properties than the monetite one. Compared to brushite, a 10-fold increase of sensitivity was obtained with the brushite cement-based biosensor, which highlights the effect of brushite crystal formation in the presence of the enzyme in the biosensor performance. Several variables involved in the enzyme immobilization method such as glutaraldehyde cross-linking time, PPO/brushite ratio and thickness of the brushite-enzyme film were investigated. Furthermore, the effects of pH and temperature on biosensor performance were also optimized. Brushite cement-PPO-GA biosensor resulted in a reliable, highly sensitive, fast, inexpensive and easy analytical method for tyramine detection. Under optimal conditions (time of 15min, a ratio of 1.0 and 50μg of the brushite-enzyme mixture, 20°C and pH 6,0), a linear range of 5.8 × 10(-7) to 1.6 × 10(-5), sensitivity 1.50 × 10(3)mAM(-1) cm(-2), detection limit, 4.85 × 10(-8)M and a response time, 6s were obtained. The suitability of the proposed biosensor to determine the tyramine content in cheese samples has been explored. The mean analytical recovery of added tyramine in gouda and brie cheeses were found to be 95.5±5.8 and 96.9±7.5 respectively. A study of the tyramine content evolution over the course of a week under inadequate storage showed the importance of monitoring the degradation of certain foods. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Analysis of microdialysate monoamines, including noradrenaline, dopamine and serotonin, using capillary ultra-high performance liquid chromatography and electrochemical detection.

    Science.gov (United States)

    Ferry, Barbara; Gifu, Elena-Patricia; Sandu, Ioana; Denoroy, Luc; Parrot, Sandrine

    2014-03-01

    Electrochemical methods are very often used to detect catecholamine and indolamine neurotransmitters separated by conventional reverse-phase high performance liquid chromatography (HPLC). The present paper presents the development of a chromatographic method to detect monoamines present in low-volume brain dialysis samples using a capillary column filled with sub-2μm particles. Several parameters (repeatability, linearity, accuracy, limit of detection) for this new ultrahigh performance liquid chromatography (UHPLC) method with electrochemical detection were examined after optimization of the analytical conditions. Noradrenaline, adrenaline, serotonin, dopamine and its metabolite 3-methoxytyramine were separated in 1μL of injected sample volume; they were detected above concentrations of 0.5-1nmol/L, with 2.1-9.5% accuracy and intra-assay repeatability equal to or less than 6%. The final method was applied to very low volume dialysates from rat brain containing monoamine traces. The study demonstrates that capillary UHPLC with electrochemical detection is suitable for monitoring dialysate monoamines collected at high sampling rate.

  14. Development of advanced carbon based composite electrodes for the detection and the degradation of organic pollutants in water via electrochemical/photoelectrochemical processes

    OpenAIRE

    2014-01-01

    Ph.D. (Chemistry) In this study, carbon based electrode materials such as glassy carbon, graphene, diamond and exfoliated graphite were explored as suitable electrode materials for electrochemical detection, electrochemical and photoelectrochemical degradation of organic water pollutants. Graphene modified glassy carbon electrode sensor was developed for bisphenol A. Cyclic voltammetry was used to study the electrochemical properties of the prepared graphene- modified glassy carbon electro...

  15. Lab-on-a-chip for rapid electrochemical detection of nerve agent Sarin

    DEFF Research Database (Denmark)

    Tan, Hsih-Yin; Loke, Weng Keong; Nguyen, Nam-Trung

    2014-01-01

    , sensitive and easy to use portable test kit would be of interest to first responders investigating such attacks. We report here an amperometric-based approach for detecting trace amounts of Sarin in water samples using a screen-printed electrode (SPE) integrated in a microfluidic chip. Enzymatic inhibition...

  16. Sensitive detection of hydrocarbon gases using electrochemically Pd-modified ZnO chemiresistors.

    Science.gov (United States)

    Dilonardo, Elena; Penza, Michele; Alvisi, Marco; Cassano, Gennaro; Di Franco, Cinzia; Palmisano, Francesco; Torsi, Luisa; Cioffi, Nicola

    2017-01-01

    Pristine and electrochemically Pd-modified ZnO nanorods (ZnO NRs) were proposed as active sensing layers in chemiresistive gas sensors for hydrocarbon (HC) gas detection (e.g., CH4, C3H8, C4H10). The presence of Pd nanoparticles (NPs) on the surface of ZnO NRs, obtained after the thermal treatment at 550 °C, was revealed by morphological and surface chemical analyses, using scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. The effect of the Pd catalyst on the performance of the ZnO-based gas sensor was evaluated by comparing the sensing results with those of pristine ZnO NRs, at an operating temperature of 300 °C and for various HC gas concentrations in the range of 30-1000 ppm. The Pd-modified ZnO NRs showed a higher selectivity and sensitivity compared to pristine ZnO NRs. The mean sensitivity of Pd-modified ZnO NRs towards the analyzed HCs gases increased with the length of the hydrocarbon chain of the target gas molecule. Finally, the evaluation of the selectivity revealed that the presence or the absence of metal nanoparticles on ZnO NRs improves the selectivity in the detection of specific HCs gaseous molecules.

  17. Identification of upper respiratory tract pathogens using electrochemical detection on an oligonucleotide microarray.

    Directory of Open Access Journals (Sweden)

    Michael J Lodes

    Full Text Available Bacterial and viral upper respiratory infections (URI produce highly variable clinical symptoms that cannot be used to identify the etiologic agent. Proper treatment, however, depends on correct identification of the pathogen involved as antibiotics provide little or no benefit with viral infections. Here we describe a rapid and sensitive genotyping assay and microarray for URI identification using standard amplification and hybridization techniques, with electrochemical detection (ECD on a semiconductor-based oligonucleotide microarray. The assay was developed to detect four bacterial pathogens (Bordetella pertussis, Streptococcus pyogenes, Chlamydia pneumoniae and Mycoplasma pneumoniae and 9 viral pathogens (adenovirus 4, coronavirus OC43, 229E and HK, influenza A and B, parainfluenza types 1, 2, and 3 and respiratory syncytial virus. This new platform forms the basis for a fully automated diagnostics system that is very flexible and can be customized to suit different or additional pathogens. Multiple probes on a flexible platform allow one to test probes empirically and then select highly reactive probes for further iterative evaluation. Because ECD uses an enzymatic reaction to create electrical signals that can be read directly from the array, there is no need for image analysis or for expensive and delicate optical scanning equipment. We show assay sensitivity and specificity that are excellent for a multiplexed format.

  18. Determination of Active Ingredients of Hawthorn by Capillary Electrophoresis with Electrochemical Detection

    Institute of Scientific and Technical Information of China (English)

    TANG Zhu-Xing; ZENG Yi-Kun; ZHOU Yun; ZANG Shu-Liang; HE Pin-Gang; FANG Yu-Zhi

    2006-01-01

    A method based on capillary electrophoresis with electrochemical detection has been developed for the separation and determination of epicatechin, kaempferol, chlorogenic acid, 4-hydroxybenzoic acid, quercetin and protocatechuic acid in hawthorn for the first time. The effects of working electrode potential, pH and concentration of running buffer, separation voltage and injection time on CE-ED were investigated. Under the optimum conditions,the analytes could be separated in a 60 mmol·L-1 borate buffer (pH 8.7) within 21 min. A 300 μm diameter carbon disk electrode has a good response at +0.95 V (vs. SCE) for all analytes. The response was linear over three orders of magnitude with detection limits (S/N=3) ranging from 3×10-8 to2×10-7 g·mL-1 for the analytes. The method has been successfully applied to the analysis of real sample, with satisfactory results.

  19. A simple preparation of graphite/gelatin composite for electrochemical detection of dopamine.

    Science.gov (United States)

    Rajkumar, Chellakannu; Thirumalraj, Balamurugan; Chen, Shen-Ming; Chen, His-An

    2017-02-01

    In this study, we demonstrate a simple preparation of graphite (GR) sheets assisted with gelatin (GLN) polypeptide composite was developed for sensitive detection of dopamine (DA) sensor. The GR/GLN composite was prepared by GR powder in GLN solution (5mg/mL) via sonication process. The prepared GR/GLN composite displays well dispersion ability in biopolymer matrix and characterized via scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS) studies. The GR/GLN modified electrode showed an excellent electrocatalytic activity toward the oxidation of DA, suggesting that the successful formation of GR sheets crosslinked with the functional groups of GLN polypeptide. In addition, the GR/GLN modified electrode achieved a wide linear response ranging from 0.05 to 79.5μM with a detection limit of 0.0045μM. The calculated analytical sensitivity of the sensor was 1.36±0.02μAμM(-1)cm(-2). Conversely, the modified electrode demonstrates a good storage stability, reproducibility and repeatability. In addition, the sensor manifests the determination of DA in human serum and urine samples for practical applications. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Disposable electrochemical DNA-array for PCR amplified detection of hazelnut allergens in foodstuffs.

    Science.gov (United States)

    Bettazzi, Francesca; Lucarelli, Fausto; Palchetti, Ilaria; Berti, Francesca; Marrazza, Giovanna; Mascini, Marco

    2008-04-28

    An electrochemical low-density DNA-array has been designed and implemented to be used in combination with polymerase chain reaction (PCR) in order to investigate the presence of hazelnut major allergens (Cor a 1.04, Cor a 1.03) in foodstuff. Unmodified PCR products were captured at the sensor interface via sandwich hybridization with surface-tethered probes and biotinylated signalling probes. The resulting biotinylated hybrids were coupled with a streptavidin-alkaline phosphatase conjugate and then exposed to a alpha-naphthyl phosphate solution. Differential pulse voltammetry was finally used to detect the alpha-naphthol signal. The detection limits for Cor a 1.03 and Cor a 1.04 were 0.3 and 0.1 nmol L(-1), respectively (R.S.D. 10%). The optimized conditions were used to test several commercially available foodstuffs, claiming to contain or not the targeted nuts. The results were compared with those obtained with classical ELISA tests.

  1. Sensitive detection of hydrocarbon gases using electrochemically Pd-modified ZnO chemiresistors

    Science.gov (United States)

    Alvisi, Marco; Cassano, Gennaro; Di Franco, Cinzia; Palmisano, Francesco; Torsi, Luisa

    2017-01-01

    Summary Pristine and electrochemically Pd-modified ZnO nanorods (ZnO NRs) were proposed as active sensing layers in chemiresistive gas sensors for hydrocarbon (HC) gas detection (e.g., CH4, C3H8, C4H10). The presence of Pd nanoparticles (NPs) on the surface of ZnO NRs, obtained after the thermal treatment at 550 °C, was revealed by morphological and surface chemical analyses, using scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. The effect of the Pd catalyst on the performance of the ZnO-based gas sensor was evaluated by comparing the sensing results with those of pristine ZnO NRs, at an operating temperature of 300 °C and for various HC gas concentrations in the range of 30–1000 ppm. The Pd-modified ZnO NRs showed a higher selectivity and sensitivity compared to pristine ZnO NRs. The mean sensitivity of Pd-modified ZnO NRs towards the analyzed HCs gases increased with the length of the hydrocarbon chain of the target gas molecule. Finally, the evaluation of the selectivity revealed that the presence or the absence of metal nanoparticles on ZnO NRs improves the selectivity in the detection of specific HCs gaseous molecules. PMID:28144567

  2. Synthesis of Ag nanoparticles for the electrochemical detection of anticancer drug flutamide

    Institute of Scientific and Technical Information of China (English)

    Farzaneh Ahmadi; Jahan Bakhsh Raoof; Reza Ojani; Mehdi Baghayeri; Moslem Mansour Lakouraj; Hamed Tashakkorian

    2015-01-01

    Ag nanoparticles were synthesized on the surface of a glassy carbon electrode modified with p‐tert‐butylcalix[4]arene and p‐tert‐butylcalix[6]arene by the deposition of Ag+at an open circuit potential followed by the electrochemical reduction of the Ag+. The presence of the calixarene layer on the electrode surface controlled the particle size and prevented agglomeration. Cyclic voltam‐metry showed that the Ag nanoparticles on the modified glassy carbon electrode had good catalytic ability for the reduction of flutamide. The effects of calixarene concentration, potential applied for the reduction of Ag+, number of calixarene layers, and pH value on the electrocatalytic activity of the Ag nanoparticles were investigated. The modified electrode had a linear range in differential pulse voltammetry of 10−1000 µmol/L with a detection limit of 9.33 µmol/L for flutamide at an S/N=3. The method was applied to the detection of flutamide in practical samples.

  3. Edge promoted ultrasensitive electrochemical detection of organic bio-molecules on epitaxial graphene nanowalls.

    Science.gov (United States)

    Kumar Roy, Pradip; Ganguly, Abhijit; Yang, Wei-Hsun; Wu, Chien-Ting; Hwang, Jih-Shang; Tai, Yian; Chen, Kuei-Hsien; Chen, Li-Chyong; Chattopadhyay, Surojit

    2015-08-15

    We report the simultaneous electrochemical detection of dopamine (DA), uric acid (UA) and ascorbic acid (AA) on three dimensional (3D) unmodified 'as-grown' epitaxial graphene nanowall arrays (EGNWs). The 3D few layer EGNWs, unlike the 2D planar graphene, offers an abundance of vertically oriented nano-graphitic-edges that exhibit fast electron-transfer kinetics and high electroactive surface area to geometrical area (EAA/GA≈134%), as evident from the Fe(CN)6(3-/4-) redox kinetic study. The hexagonal sp(2)-C domains, on the basal plane of the EGNWs, facilitate efficient adsorption via spontaneous π-π interaction with the aromatic rings in DA and UA. Such affinity together with the fast electron kinetics enables simultaneous and unambiguous identification of individual AA, DA and UA from their mixture. The unique edge dominant EGNWs result in an unprecedented low limit of detection (experimental) of 0.033 nM and highest sensitivity of 476.2 µA/µM/cm(2), for UA, which are orders of magnitude higher than comparable existing reports. A reaction kinetics based modeling of the edge-oriented 3D EGNW system is proposed to illustrate the superior electro-activity for bio-sensing applications.

  4. Detecting proton exchange membrane fuel cell hydrogen leak using electrochemical impedance spectroscopy method

    Science.gov (United States)

    Mousa, Ghassan; Golnaraghi, Farid; DeVaal, Jake; Young, Alan

    2014-01-01

    When a proton exchange membrane (PEM) fuel cell runs short of hydrogen, it suffers from a reverse potential fault that, when driven by neighboring cells, can lead to anode catalyst degradation and holes in the membrane due to local heat generation. As a result, hydrogen leaks through the electrically-shorted membrane-electrode assembly (MEA) without being reacted, and a reduction in fuel cell voltage is noticed. Such voltage reduction can be detected by using electrochemical impedance spectroscopy (EIS). To fully understand the reverse potential fault, the effect of hydrogen crossover leakage in a commercial MEA is measured by EIS at different differential pressures between the anode and cathode. Then the signatures of these leaky cells were compared with the signatures of a no-leaky cells at different oxygen concentrations with the same current densities. The eventual intent of this early stage work is to develop an on-board diagnostics system that can be used to detect and possibly prevent cell reversal failures, and to permit understanding the status of crossover or transfer leaks versus time in operation.

  5. Aptamer-based biosensor for label-free detection of ethanolamine by electrochemical impedance spectroscopy.

    Science.gov (United States)

    Liang, Gang; Man, Yan; Jin, Xinxin; Pan, Ligang; Liu, Xinhui

    2016-09-14

    A label-free sensing assay for ethanolamine (EA) detection based on G-quadruplex-EA binding interaction is presented by using G-rich aptamer DNA (Ap-DNA) and electrochemical impedance spectroscopy (EIS). The presence of K(+) induces the Ap-DNA to form a K(+)-stabilized G-quadruplex structure which provides binding sites for EA. The sensing mechanism was further confirmed by circular dichroism (CD) spectroscopy and EIS measurement. As a result, the charge transfer resistance (RCT) is strongly increased as demonstrated by using the ferro/ferricyanide ([Fe(CN)6](3-/4-)) as a redox probe. Under the optimized conditions, a linear relationship between ΔRCT and EA concentration was obtained over the range of 0.16 nM and 16 nM EA, with a detection limit of 0.08 nM. Interference by other selected chemicals with similar structure was negligible. Analytical results of EA spiked into tap water and serum by the sensor suggested the assay could be successfully applied to real sample analysis. With the advantages of high sensitivity, selectivity and simple sensor construction, this method is potentially suitable for the on-site monitoring of EA contamination.

  6. Integrating Microbial Electrochemical Technology with Forward Osmosis and Membrane Bioreactors: Low-Energy Wastewater Treatment, Energy Recovery and Water Reuse

    KAUST Repository

    Werner, Craig M.

    2014-06-01

    Wastewater treatment is energy intensive, with modern wastewater treatment processes consuming 0.6 kWh/m3 of water treated, half of which is required for aeration. Considering that wastewater contains approximately 2 kWh/m3 of energy and represents a reliable alternative water resource, capturing part of this energy and reclaiming the water would offset or even eliminate energy requirements for wastewater treatment and provide a means to augment traditional water supplies. Microbial electrochemical technology is a novel technology platform that uses bacteria capable of producing an electric current outside of the cell to recover energy from wastewater. These bacteria do not require oxygen to respire but instead use an insoluble electrode as their terminal electron acceptor. Two types of microbial electrochemical technologies were investigated in this dissertation: 1) a microbial fuel cell that produces electricity; and 2) a microbial electrolysis cell that produces hydrogen with the addition of external power. On their own, microbial electrochemical technologies do not achieve sufficiently high treatment levels. Innovative approaches that integrate microbial electrochemical technologies with emerging and established membrane-based treatment processes may improve the overall extent of wastewater treatment and reclaim treated water. Forward osmosis is an emerging low-energy membrane-based technology for seawater desalination. In forward osmosis water is transported across a semipermeable membrane driven by an osmotic gradient. The microbial osmotic fuel cell described in this dissertation integrates a microbial fuel cell with forward osmosis to achieve wastewater treatment, energy recovery and partial desalination. This system required no aeration and generated more power than conventional microbial fuel cells using ion exchange membranes by minimizing electrochemical losses. Membrane bioreactors incorporate semipermeable membranes within a biological wastewater

  7. A Fully Integrated and Miniaturized Heavy-metal-detection Sensor Based on Micro-patterned Reduced Graphene Oxide

    Science.gov (United States)

    Xuan, Xing; Hossain, Md. Faruk; Park, Jae Yeong

    2016-09-01

    For this paper, a fully integrated and highly miniaturized electrochemical sensor was designed and fabricated on a silicon substrate. A solvothermal-assisted reduced graphene oxide named “TRGO” was then successfully micro-patterned using a lithography technique, followed by the electrodeposition of bismuth (Bi) on the surface of the micro-patterned TRGO for the electrochemical detection of heavy metal ions. The fully integrated electrochemical micro-sensor was then measured and evaluated for the detection of cadmium and lead-heavy metal ions in an acetic-acid buffered solution using the square wave anodic stripping voltammetry (SWASV) technique. The fabricated micro-sensor exhibited a linear detection range of 1.0 μg L-1 to 120.0 μg L-1 for both of the metal ions, and detection limits of 0.4 μg L-1 and 1.0 μg L-1 were recorded for the lead and cadmium (S/N = 3), respectively. Drinking-water samples were used for the practical assessment of the fabricated micro-sensor, and it showed an acceptable detection performance regarding the metal ions.

  8. Electrochemical detection of uric acid using ruthenium-dioxide-coated carbon nanotube directly grown onto Si wafer

    Science.gov (United States)

    Shih, Yi-Ting; Lee, Kuei-Yi; Lin, Chung-Kuang

    2015-12-01

    Carbon nanotubes (CNTs) directly grown onto a Si substrate by thermal chemical vapor deposition were used in uric acid (UA) detection. The process is simple and formation is easy without the need for additional chemical treatments. However, CNTs lack selectivity and sensitivity to UA. To enhance the electrochemical analysis, ruthenium oxide was used as a catalytic mediator in the modification of electrodes. The electrochemical results show that RuO2 nanostructures coated onto CNTs can strengthen the UA signal. The peak currents of RuO2 nanostructures coated onto CNTs linearly increase with increasing UA concentration, meaning that they can work as electrodes for UA detection. The lowest detection limit and highest sensitivity were 55 nM and 4.36 µA/µM, respectively. Moreover, the characteristics of RuO2 nanostructures coated onto CNTs were examined by scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy.

  9. Copper sulfide nanoparticle-decorated graphene as a catalytic amplification platform for electrochemical detection of alkaline phosphatase activity.

    Science.gov (United States)

    Peng, Juan; Han, Xiao-Xia; Zhang, Qing-Chun; Yao, Hui-Qin; Gao, Zuo-Ning

    2015-06-01

    Copper sulfide nanoparticle-decorated graphene sheet (CuS/GR) was successfully synthesized and used as a signal amplification platform for electrochemical detection of alkaline phosphatase activity. First, CuS/GR was prepared through a microwave-assisted hydrothermal approach. The CuS/GR nanocomposites exhibited excellent electrocatalytic activity toward the oxidation of ALP hydrolyzed products such as 1-naphthol, which produced a current response. Thus, a catalytic amplification platform based on CuS/GR nanocomposite for electrochemical detection of ALP activity was designed using 1-naphthyl phosphate as a model substrate. The current response increased linearly with ALP concentration from 0.1 to 100 U L(-1) with a detection limit of 0.02 U L(-1). The assay was applied to estimate ALP activity in human serum samples with satisfactory results. This strategy may find widespread and promising applications in other sensing systems that involves ALP.

  10. Novel nanoarchitectures for electrochemical biosensing

    Science.gov (United States)

    Archibald, Michelle M.

    Sensitive, real-time detection of biomarkers is of critical importance for rapid and accurate diagnosis of disease for point-of-care (POC) technologies. Current methods, while sensitive, do not adequately allow for POC applications due to several limitations, including complex instrumentation, high reagent consumption, and cost. We have investigated two novel nanoarchitectures, the nanocoax and the nanodendrite, as electrochemical biosensors towards the POC detection of infectious disease biomarkers to overcome these limitations. The nanocoax architecture is composed of vertically-oriented, nanoscale coaxial electrodes, with coax cores and shields serving as integrated working and counter electrodes, respectively. The dendritic structure consists of metallic nanocrystals extending from the working electrode, increasing sensor surface area. Nanocoaxial- and nanodendritic-based electrochemical sensors were fabricated and developed for the detection of bacterial toxins using an electrochemical enzyme-linked immunosorbent assay (ELISA) and differential pulse voltammetry (DPV). Proof-of-concept was demonstrated for the detection of cholera toxin (CT). Both nanoarchitectures exhibited levels of sensitivity that are comparable to the standard optical ELISA used widely in clinical applications. In addition to matching the detection profile of the standard ELISA, these electrochemical nanosensors provide a simple electrochemical readout and a miniaturized platform with multiplexing capabilities toward POC implementation. Further development as suggested in this thesis may lead to increases in sensitivity, enhancing the attractiveness of the architectures for future POC devices.

  11. Real-time automatic detection electrochemical sensor based on collaborative computing with SoC%基于片上系统协同计算的实时自动检测电化学传感器

    Institute of Scientific and Technical Information of China (English)

    魏斌; 林楠; 李跃新

    2015-01-01

    针对应用于生物体内特征物质检测与跟踪的电化学传感器的智能化和集成化问题,提出了一种基于片上系统的支持实时数据自动检测的电化学传感器。将应用于电化学传感器结构,通过将测量样品、检测溶液接口、多电极和检测传导器等单元集成在片上系统,结合信号转换和电源装置,实现电化学传感器的独立计算、存储和通信功能。通过实现待测量物多电极、检测溶液电极子和单片机逻辑控制的协同计算满足自动检测需求。基于数据整合与自动化处理,设计了支持实时数据检测的电化学传感器。验证结果表明:在数据检测精度和实时性方面所提方案明显优于传统的非片上系统电化学传感器。%Aiming at intelligence and integration problems of electrochemical sensor for detecting and tracking of feature substances in body of living things,put forward a kind of electrochemical sensor supported system on chip for real-time data automatic detection. The structure is applied to electrochemical sensor,measured samples, detecting solution interface,multi-electrode and detection transmitter and other units are integrated in SoC, combined detected with signal conversion and power device,to achieve independent computation,storage and communication function of electrochemical sensors. Through realization of collaborative calculation of multi-electrode of object to be measured,test solution electrode and MCU logic control,to meet the demand of automatic detection. Based on data integration and automation processing,design electrochemical sensor to support real-time data detection. Test results show that,the proposed scheme is superior to the traditional electrochemical sensor in data detection precision and real-time.

  12. 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

  13. Counterfeit integrated circuits detection and avoidance

    CERN Document Server

    Tehranipoor, Mark (Mohammad); Forte, Domenic

    2015-01-01

    This timely and exhaustive study offers a much-needed examination of the scope and consequences of the electronic counterfeit trade.  The authors describe a variety of shortcomings and vulnerabilities in the electronic component supply chain, which can result in counterfeit integrated circuits (ICs).  Not only does this book provide an assessment of the current counterfeiting problems facing both the public and private sectors, it also offers practical, real-world solutions for combatting this substantial threat.   ·      Helps beginners and practitioners in the field by providing a comprehensive background on the counterfeiting problem; ·      Presents innovative taxonomies for counterfeit types, test methods, and counterfeit defects, which allows for a detailed analysis of counterfeiting and its mitigation; ·      Provides step-by-step solutions for detecting different types of counterfeit ICs; ·      Offers pragmatic and practice-oriented, realistic solutions to counterfeit IC d...

  14. Detection of Hepatitis C core antibody by dual-affinity yeast chimera and smartphone-based electrochemical sensing.

    Science.gov (United States)

    Aronoff-Spencer, Eliah; Venkatesh, A G; Sun, Alex; Brickner, Howard; Looney, David; Hall, Drew A

    2016-12-15

    Yeast cell lines were genetically engineered to display Hepatitis C virus (HCV) core antigen linked to gold binding peptide (GBP) as a dual-affinity biobrick chimera. These multifunctional yeast cells adhere to the gold sensor surface while simultaneously acting as a "renewable" capture reagent for anti-HCV core antibody. This streamlined functionalization and detection strategy removes the need for traditional purification and immobilization techniques. With this biobrick construct, both optical and electrochemical immunoassays were developed. The optical immunoassays demonstrated detection of anti-HCV core antibody down to 12.3pM concentrations while the electrochemical assay demonstrated higher binding constants and dynamic range. The electrochemical format and a custom, low-cost smartphone-based potentiostat ($20 USD) yielded comparable results to assays performed on a state-of-the-art electrochemical workstation. We propose this combination of synthetic biology and scalable, point-of-care sensing has potential to provide low-cost, cutting edge diagnostic capability for many pathogens in a variety of settings.

  15. Detection of the Lipopeptide Pam3CSK4 Using a Hybridized Toll-like Receptor Electrochemical Sensor.

    Science.gov (United States)

    She, Zhe; Topping, Kristin; Ma, Tianxiao; Zhao, Tiantian; Zhou, Wenxia; Kamal, Ajar; Ahmadi, Soha; Kraatz, Heinz-Bernhard

    2017-04-12

    Electrochemical detection of Pam3CSK4, a synthetic triacylated lipopeptide that mimics the structural moieties of its natural Gram negative bacterial pathogen-associated molecular pattern (PAMP) counterpart, has been achieved using hybridized toll-like receptors (TLR) combining TLR1 and TLR2 onto a single sensor surface. These sensors represent the first hybridized TLR sensors. The limit of detection for Pam3CSK4 attained was 7.5 μg/mL, which is within the same order of magnitude for that of the more labor-intensive and time-consuming cell-assay technique, 2.0 μg/mL. The results gathered in these electrochemical experiments show that sensors fabricated by immobilizing a mixture of cooperative TLR1 and -2 generate higher responses when exposed to the analyte in comparison to the control sensors fabricated using pure TLR1 or -2 standalone. A PAMP selectivity test was carried out in line with our inspiration from the mammalian innate immune response. TLRs1-5 as standalone biorecognition elements and the hybridized "TLR1 and 2" sensor surface were investigated, understanding the known TLR-PAMP interactions, through the exploitation of this electrochemical sensor fabrication technique. The experimental result is consistent with observations from previously published in vivo and in vitro studies, and it is the first demonstration of the simultaneous evaluation of electrochemical responses from multiple, unique fabricated TLR sensor surfaces against the same analyte.

  16. Rapid prototyping of microfluidic devices with integrated wrinkled gold micro-/nano textured electrodes for electrochemical analysis.

    Science.gov (United States)

    Gabardo, C M; Adams-McGavin, R C; Vanderfleet, O M; Soleymani, L

    2015-08-21

    Fully-integrated electro-fluidic systems with micro-/nano-scale features have a wide range of applications in lab-on-a-chip systems used for biosensing, biological sample processing, and environmental monitoring. Rapid prototyping of application-specific electro-fluidic systems is envisioned to facilitate the testing, validation, and market translation of several lab-on-a-chip systems. Towards this goal, we developed a rapid prototyping process for creating wrinkled micro-/nano-textured electrodes on shrink memory polymers, fabricating microfluidics using molds patterned by a craft-cutter, and bonding electrical and fluidic circuitries using a PDMS partial curing method optimized for creating void-free bonds at the side walls and surfaces of tall (>5 μm) micro-/nano-textured wrinkled electrodes. The resulting electro-fluidic devices, featuring closely spaced high topography electrodes for electrochemical analysis, can withstand flow-rates and burst pressures larger than 25 mL min(-1) and 125 kPa, respectively. In addition, the fully-integrated electrochemical flow-cell developed here demonstrates excellent electrochemical behaviour, with negligible scan to scan variation for over 100 cyclic voltammetry scans, and expected redox signatures measured under various voltage scan rates and fluidic flow rates.

  17. Simultaneous electrochemical detection of dopamine and uric acid over ceria supported three dimensional gold nanoclusters

    Science.gov (United States)

    Palanisamy, Sivakumar

    2014-12-01

    CeO2 is well known for being an active material to support the growth of Au nanoclusters (Au NCs). In this work, three dimensional (3D) Au NCs were deposited on three different shaped CeO2 nanostructures such as nanoparticles (NPs), nanorod arrays (NRAs) and nanoflowers (NFs) modified Ti substrate for electrochemical simultaneous detection of dopamine (DA) and uric acid (UA). The electrodeposition of 3D Au NCs were carried out via cyclic voltammetric (CV) method at over-potential, while CeO2 nanostructures were deposited by galvanostatic constant current method under the optimized conditions. The morphology and elemental composition analysis of 3D Au NCs with CeO2 nanostructures were characterized by SEM, XRD, XPS and EDAX measurements. The electrocatalytic activity of 3D Au NCs on different CeO2 supports were thoroughly investigated by using voltammetric and amperometric techniques. According to the obtained results, CeO2 NPs supported 3D Au NCs (3D Au NCs@CeO2 NPs) displayed strong signal for DA as compared to that of CeO2 NRAs (3D Au NCs@CeO2 NRAs) and CeO2 NFs supported 3D Au NCs (3D Au NCs@CeO2 NFs). In addition, the 3D Au NCs@CeO2 NPs electrode resulted in more sensitive and simultaneous detection of DA in the presence of excess UA. Thus, the 3D Au NCs@CeO2 NPs electrode can practically be applied for the detection of DA using biological samples.

  18. Detection of estradiol at an electrochemical immunosensor with a Cu UPD|DTBP-Protein G scaffold.

    Science.gov (United States)

    Liu, Xiaoqiang; Wang, Xinhai; Zhang, Jiamei; Feng, Heqing; Liu, Xiuhua; Wong, Danny K Y

    2012-05-15

    A copper monolayer was formed on a gold electrode surface via underpotential deposition (UPD) method to construct a Cu UPD|DTBP-Protein G immunosensor for the sensitive detection of 17β-estradiol. Copper UPD monolayer can minimize the non-specific adsorption of biological molecules on the immunosensor surface and enhance the binding efficiency between immunosensor surface and thiolated Protein G. The crosslinker DTBP (Dimethyl 3,3'-dithiobispropionimidate · 2HCl) has strong ability to immobilize Protein G molecules on the electrode surface and the immobilized Protein G provides an orientation-controlled binding of antibodies. A monolayer of propanethiol was firstly self-assembled on the gold electrode surface, and a copper monolayer was deposited via UPD on the propanethiol modified electrode. Propanethiol monolayer helps to stabilize the copper monolayer by pushing the formation and stripping potentials of the copper UPD monolayer outside the potential range in which copper monolayer can be damaged easily by oxygen in air. A droplet DTBP-Protein G was then applied on the modified electrode surface followed by the immobilization of estradiol antibody. Finally, a competitive immunoassay was conducted between estradiol-BSA (bovine serum albumin) conjugate and free estradiol for the limited binding sites of estradiol antibody. Square wave voltammetry (SWV) was employed to monitor the electrochemical reduction current of ferrocenemethanol and the SWV current decreased with the increase of estradiol-BSA conjugate concentration at the immunosensor surface. Calibration of immunosensors in waste water samples spiked with 17β-estradiol yielded a linear response up to ≈ 2200 pg mL(-1), a sensitivity of 3.20 μA/pg mL(-1) and a detection limit of 12 pg mL(-1). The favorable characteristics of the immunosensors such as high selectivity, sensitivity and low detection limit can be attributed to the Cu UPD|DTBP-Protein G scaffold.

  19. Probing the electrochemical behaviour of SWCNT-cobalt nanoparticles and their electrocatalytic activities towards the detection of nitrite at acidic and physiological pH conditions

    CSIR Research Space (South Africa)

    Adekunle, AS

    2010-05-01

    Full Text Available The electrochemical decoration of edge plane pyrolytic graphite electrode (EPPGE) with cobalt and cobalt oxide nanoparticles integrated with and without single-walled carbon nanotubes (SWCNTs) is described. Successful modification of the electrodes...

  20. Design and adaptation of miniaturized electrochemical devices integrating carbon nanotube-based sensors to commercial CE equipment.

    Science.gov (United States)

    Arribas, Alberto Sánchez; Moreno, Mónica; Bermejo, Esperanza; Angeles Lorenzo, M; Zapardiel, Antonio; Chicharro, Manuel

    2009-10-01

    The design of new electrochemical devices integrating carbon nanotube sensors and their adaptation to commercial CE equipments are described. One of these designs was made for using commercial screen-printed electrodes, whereas the second was projected for coupling commercial glassy carbon electrodes. The electrochemical characterization of these devices revealed that their hydrodynamic behaviour is strongly influenced by the electrode modification with multi-wall carbon nanotubes that provided faster and/or more sensitive signals. The analytical applicability of these devices was illustrated for the CZE separation of chlorinated phenols and the MEKC separation of endocrine disruptors, where the use of carbon nanotube sensors has proved to be advantageous when compared with unmodified ones, with good electrocatalytic properties combined with acceptable background currents and a remarkable resistance to passivation.

  1. A 3D Microfluidic Chip for Electrochemical Detection of Hydrolysed Nucleic Bases by a Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Jana Vlachova

    2015-01-01

    Full Text Available Modification of carbon materials, especially graphene-based materials, has wide applications in electrochemical detection such as electrochemical lab-on-chip devices. A glassy carbon electrode (GCE modified with chemically alternated graphene oxide was used as a working electrode (glassy carbon modified by graphene oxide with sulphur containing compounds and Nafion for detection of nucleobases in hydrolysed samples (HCl pH = 2.9, 100 °C, 1 h, neutralization by NaOH. It was found out that modification, especially with trithiocyanuric acid, increased the sensitivity of detection in comparison with pure GCE. All processes were finally implemented in a microfluidic chip formed with a 3D printer by fused deposition modelling technology. As a material for chip fabrication, acrylonitrile butadiene styrene was chosen because of its mechanical and chemical stability. The chip contained the one chamber for the hydrolysis of the nucleic acid and another for the electrochemical detection by the modified GCE. This chamber was fabricated to allow for replacement of the GCE.

  2. Development of electrochemical immunosensors based on different serum antibody immobilization methods for detection of Japanese encephalitis virus

    Science.gov (United States)

    Tran, Quang Huy; Hanh Nguyen, Thi Hong; Mai, Anh Tuan; Thuy Nguyen, Thi; Khue Vu, Quang; Nga Phan, Thi

    2012-03-01

    This paper describes the development of electrochemical immunosensors based on human serum antibodies with different immobilization methods for detection of Japanese encephalitis virus (JEV). Human serum containing anti-JEV antibodies was used to immobilize onto the surface of silanized interdigitated electrodes by four methods: direct adsorption (APTES-serum), covalent binding with a cross linker of glutaraldehyde (APTES-GA-serum), covalent binding with a cross linker of glutaraldehyde combined with anti-human IgG (APTES-GA-anti-HIgG-serum) and covalent binding with a cross linker of glutaraldehyde combined with a bioaffinity of protein A (APTES-GA-PrA-serum). Atomic force microscopy was used to verify surface characteristics of the interdigitated electrodes before and after treatment with serum antibodies. The output signal of the immunosensors was measured by the change of conductivity resulting from the specific binding of JEV antigens and serum antibodies immobilized on the electrodes, with the help of horseradish peroxidase (HRP)-labeled secondary antibody against JEV. The results showed that the APTES-GA-PrA-serum method provided the highest signal of the electrochemical immunosensor for detection of JEV antigens, with the linear range from 25 ng ml-1 to 1 μg ml-1, and the limit of detection was about 10 ng ml-1. This study shows a potential development of novel electrochemical immunosensors applied for virus detection in clinical samples in case of possible outbreaks.

  3. Electrochemical DNA probe for Hg(2+) detection based on a triple-helix DNA and Multistage Signal Amplification Strategy.

    Science.gov (United States)

    Wang, Huan; Zhang, Yihe; Ma, Hongmin; Ren, Xiang; Wang, Yaoguang; Zhang, Yong; Wei, Qin

    2016-12-15

    In this work, an ultrasensitive electrochemical sensor was developed for detection of Hg(2+). Gold nanoparticles decorated bovine serum albumin reduction of graphene oxide (AuNP-BSA-rGO) were used as subsurface material for the immobilization of triple-helix DNA. The triple-helix DNA containing a thiol labelled single-stranded DNA (sDNA) and a thymine-rich DNA (T-rich DNA), which could be unwinded in the present of Hg(2+) to form more stable thymine-Hg(2+)-thymine (T-Hg(2+)-T) complex. T-Hg(2+)-T complex was then removed and the sDNA was left on the electrode. At this time, gold nanoparticle carrying thiol labelled cytosine-rich complementary DNA (cDNA-AuNP) could bind with the free sDNA. Meanwhile, the other free cDNA on AuNP could bind with each other in the present of Ag(+) to form the stable cytosine-Ag(+)-cytosine (C-Ag(+)-C) complex and circle amplification. Plenty of C-Ag(+)-C could form silver nanoclusters by electrochemical reduction and the striping signal of Ag could be measured for purpose of the final electrochemical detection of Hg(2+). This sensor could detect Hg(2+) over a wide concentration range from 0.1 to 130nM with a detection limit of 0.03nM.

  4. Aptamer-MIP hybrid receptor for highly sensitive electrochemical detection of prostate specific antigen.

    Science.gov (United States)

    Jolly, Pawan; Tamboli, Vibha; Harniman, Robert L; Estrela, Pedro; Allender, Chris J; Bowen, Jenna L

    2016-01-15

    This study reports the design and evaluation of a new synthetic receptor sensor based on the amalgamation of biomolecular recognition elements and molecular imprinting to overcome some of the challenges faced by conventional protein imprinting. A thiolated DNA aptamer with established affinity for prostate specific antigen (PSA) was complexed with PSA prior to being immobilised on the surface of a gold electrode. Controlled electropolymerisation of dopamine around the complex served to both entrap the complex, holding the aptamer in, or near to, it's binding conformation, and to localise the PSA binding sites at the sensor surface. Following removal of PSA, it was proposed that the molecularly imprinted polymer (MIP) cavity would act synergistically with the embedded aptamer to form a hybrid receptor (apta-MIP), displaying recognition properties superior to that of aptamer alone. Electrochemical impedance spectroscopy (EIS) was used to evaluate subsequent rebinding of PSA to the apta-MIP surface. The apta-MIP sensor showed high sensitivity with a linear response from 100pg/ml to 100ng/ml of PSA and a limit of detection of 1pg/ml, which was three-fold higher than aptamer alone sensor for PSA. Furthermore, the sensor demonstrated low cross-reactivity with a homologous protein (human Kallikrein 2) and low response to human serum albumin (HSA), suggesting possible resilience to the non-specific binding of serum proteins.

  5. Characterization of Screen-Printed Organic Electrochemical Transistors to Detect Cations of Different Sizes

    Directory of Open Access Journals (Sweden)

    Laura Contat-Rodrigo

    2016-09-01

    Full Text Available A novel screen-printing fabrication method was used to prepare organic electrochemical transistors (OECTs based on poly(3,4-ethylenedioxythiophene doped with polysterene sulfonate (PEDOT:PSS. Initially, three types of these screen-printed OECTs with a different channel and gate areas ratio were compared in terms of output characteristics, transfer characteristics, and current modulation in a phosphate buffered saline (PBS solution. Results confirm that transistors with a gate electrode larger than the channel exhibit higher modulation. OECTs with this geometry were therefore chosen to investigate their ion-sensitive properties in aqueous solutions of cations of different sizes (sodium and rhodamine B. The effect of the gate electrode was additionally studied by comparing these all-PEDOT:PSS transistors with OECTs with the same geometry but with a non-polarizable metal gate (Ag. The operation of the all-PEDOT:PSS OECTs yields a response that is not dependent on a Na+ or rhodamine concentration. The weak modulation of these transistors can be explained assuming that PEDOT:PSS behaves like a supercapacitor. In contrast, the operation of Ag-Gate OECTs yields a response that is dependent on ion concentration due to the redox reaction taking place at the gate electrode with Cl− counter-ions. This indicates that, for cation detection, the response is maximized in OECTs with non-polarizable gate electrodes.

  6. Electrochemical detection of interaction between capsaicin and nucleic acids in comparison to agarose gel electrophoresis.

    Science.gov (United States)

    Yilmaz, Nilay; Eksin, Ece; Karacicek, Bilge; Eraç, Yasemin; Erdem, Arzum

    2017-10-15

    In this study, the biomolecular interaction occurred between nucleic acids and Capsaicin (CPS), the active compound in chilli peppers, which has been reported to have anti-carcinogenic properties, was investigated for the first time herein using disposable electrochemical biosensor. It is aimed to perform the surface-confined interaction between CPS and different types of nucleic acids and under this aim, the experimental conditions were optimized; such as, the concentration of CPS and DNA, DNA immobilization time and interaction time etc. The detection limit of DNA was estimated based on guanine oxidation signal in the linear concentration range of DNA from 1 to 5 μg/mL, and it was found to be 0.62 μg/mL. The effect of time-dependent manner from 1 min to 30 min on the interaction of CPS with nucleic acids was explored upon to the changes at guanine signal coming from double stranded DNA and cDNA as well as PCR samples. The interaction of CPS with double stranded DNA was also determined by agarose gel electrophoresis. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Dynamics of an electrochemical biosensor for the detection of toxic substances in water

    Science.gov (United States)

    Simon, Laurent; Ospina, Juan

    2016-05-01

    A proposed analytical method focuses on electrolyte transport to the electrode of an electrochemical cell. The recombinant Escherichia coli whole-cell biosensor detects toxicity in water based on a set of biochemical reactors. Previous contributions elucidated the kinetics of product formation and validated a mathematical model for its diffusion in the chamber. This work introduces an approach to investigate the dynamics of the probe using Laplace transforms and an effective time constant. The transfer function between the electrolyte production and the total current revealed a faster response for larger electrode radii. Both the first-order and effective time constants increased with the chamber height and radius. Separation of variables yields closed-form solutions and helps estimate the kinetics of p-aminophenol generation. When the bacteria were exposed to phenol concentrations of 1.6, 8.3 and 16 ppm, the corresponding overall rate constants were 5.11x10-7, 1.13x10-6 and 1.99x10-6 (product concentration unit/s2), respectively. In addition to parameter estimation, the method can be applied to perform sensitivity analysis and aid manufacturers in meeting design specifications of biosensors.

  8. Application of liquid chromatography method with electrochemical detection for bioequivalence study of trimetazidine in human plasma.

    Science.gov (United States)

    Grabowski, Tomasz; Swierczewska, Anna; Borucka, Beata; Sawicka, Renata; Sasinowska-Motyl, Małgorzata; Gumułka, Stanisław Witold

    2012-01-01

    A method to estimate trimetazidine (CAS: 13171-25-0) levels in human plasma by means of HPLC with electrochemical detection was developed. Trimethoprim (CAS: 26807-65-8) was used as an internal standard. This method of analysis was fully validated according to the guidelines of the United States Food and Drug Administration, European Medicines Agency and Organization for Economic Co-operation and Development and Good Laboratory Practice rules. The accuracy and precision of the developed method were found to be satisfactory and stability studies showed acceptable variation (below 15%) of trimetazidine concentrations when samples were stored frozen at -75 degrees C for 54 days. The developed method was successfully used for a comparative 2 x 2 period, crossover bioequivalence study of two extended-release preparations of trimetazidine performed on 24 healthy volunteers at the steady state after multiple dosing of 35 mg twice daily for 4 days and a single 35 mg dose on the 5th day and after a single dose of 35 mg under fasting or postprandial conditions.

  9. DNA Hybridization Sensors Based on Electrochemical Impedance Spectroscopy as a Detection Tool

    Directory of Open Access Journals (Sweden)

    Jin-Young Park

    2009-11-01

    Full Text Available Recent advances in label free DNA hybridization sensors employing electrochemical impedance spectroscopy (EIS as a detection tool are reviewed. These sensors are based on the modulation of the blocking ability of an electrode modified with a probe DNA by an analyte, i.e., target DNA. The probe DNA is immobilized on a self-assembled monolayer, a conducting polymer film, or a layer of nanostructures on the electrode such that desired probe DNA would selectively hybridize with target DNA. The rate of charge transfer from the electrode thus modified to a redox indicator, e.g., [Fe(CN6]3–/4–, which is measured by EIS in the form of charge transfer resistance (Rct, is modulated by whether or not, as well as how much, the intended target DNA is selectively hybridized. Efforts made to enhance the selectivity as well as the sensitivity of DNA sensors and to reduce the EIS measurement time are briefly described along with brief future perspectives in developing DNA sensors.

  10. DNA Hybridization Sensors Based on Electrochemical Impedance Spectroscopy as a Detection Tool

    Science.gov (United States)

    Park, Jin-Young; Park, Su-Moon

    2009-01-01

    Recent advances in label free DNA hybridization sensors employing electrochemical impedance spectroscopy (EIS) as a detection tool are reviewed. These sensors are based on the modulation of the blocking ability of an electrode modified with a probe DNA by an analyte, i.e., target DNA. The probe DNA is immobilized on a self-assembled monolayer, a conducting polymer film, or a layer of nanostructures on the electrode such that desired probe DNA would selectively hybridize with target DNA. The rate of charge transfer from the electrode thus modified to a redox indicator, e.g., [Fe(CN)6]3−/4−, which is measured by EIS in the form of charge transfer resistance (Rct), is modulated by whether or not, as well as how much, the intended target DNA is selectively hybridized. Efforts made to enhance the selectivity as well as the sensitivity of DNA sensors and to reduce the EIS measurement time are briefly described along with brief future perspectives in developing DNA sensors. PMID:22303136

  11. Reversible Electrochemical Sensor for Detection of High-Charge Density Polyanion Contaminants in Heparin.

    Science.gov (United States)

    Lester, Jacob; Chandler, Timothy; Gemene, Kebede L

    2015-11-17

    We present a simple, rapid, and inexpensive electrochemical sensor based on a reversible pulsed chronopotentiometric polyanion-selective membrane electrode for the detection and quantification of oversulfated chondroitin sulfate (OSCS) and other high charge-density polyanions that could potentially be used to adulterate heparin. The membrane is free of ion exchanger and is formulated with plasticized poly(vinyl chloride) (PVC) and an inert lipophilic salt, tridodecylmethylammonium-dinonylnaphthaline sulfonate (TDMA-DNNS). The neutral salt is used to reduce membrane resistance and to ensure reversibility of the sensor. More importantly, TDMA(+) is used as the recognition element for the polyanions. Here an anodic galvanostatic current pulse is applied across the membrane to cause the extraction of the polyanions from the sample into the membrane and potential is measured at the sample-membrane interface. The measured electromotive force (emf) is proportional to the concentration and the charge density of the polyanions. High charge-density polyanion contaminants and impurities in heparin can be detected using this method since the overall equilibrium potential response of polyions increases with increasing charge density of the polyions. Here, first the potential response of pure heparin is measured at a saturation concentration, the concentration beyond which further addition of heparin does not produce a change in potential response. Then the potential response of heparin tainted with different quantities of the high charge-density contaminant is measured at a fixed total polyion concentration (heparin concentration + contaminant concentration). The latter gives a greater negative potential response due to the presence of the high charge-density contaminant. The increase in the negative potential response can be used for detection and quantification of high charge-density contaminants in heparin. We demonstrate here that 0.3% (w/w) OSCS as well as 0.1% (w

  12. Three-dimensional nitrogen-doped graphene as an ultrasensitive electrochemical sensor for the detection of dopamine.

    Science.gov (United States)

    Feng, Xiaomiao; Zhang, Yu; Zhou, Jinhua; Li, Yi; Chen, Shufen; Zhang, Lei; Ma, Yanwen; Wang, Lianhui; Yan, Xiaohong

    2015-02-14

    Three-dimensional nitrogen-doped graphene (3D N-doped graphene) was prepared through chemical vapor deposition (CVD) by using porous nickel foam as a substrate. As a model, a dopamine biosensor was constructed based on the 3D N-doped graphene porous foam. Electrochemical experiments exhibited that this biosensor had a remarkable detection ability with a wide linear detection range from 3 × 10(-6) M to 1 × 10(-4) M and a low detection limit of 1 nM. Moreover, the fabricated biosensor also showed an excellent anti-interference ability, reproducibility, and stability.

  13. Electrochemical Detection of Amyloid-β Oligomers Based on the Signal Amplification of a Network of Silver Nanoparticles.

    Science.gov (United States)

    Xia, Ning; Wang, Xin; Zhou, Binbin; Wu, Yangyang; Mao, Wenhui; Liu, Lin

    2016-08-03

    Amyloid-β oligomers (AβOs) are the most important toxic species in the brain of Alzheimer's disease (AD) patient. AβOs, therefore, are considered reliable molecular biomarkers for the diagnosis of AD. Herein, we reported a simple and sensitive electrochemical method for the selective detection of AβOs using silver nanoparticles (AgNPs) as the redox reporters and PrP(95-110), an AβOs-specific binding peptide, as the receptor. Specifically, adamantine (Ad)-labeled PrP(95-110), denoted as Ad-PrP(95-110), induced the aggregation and color change of AgNPs and the follow-up formation of a network of Ad-PrP(95-110)-AgNPs. Then, Ad-PrP(95-110)-AgNPs were anchored onto a β-cyclodextrin (β-CD)-covered electrode surface through the host-guest interaction between Ad and β-CD, thus producing an amplified electrochemical signal through the solid-state Ag/AgCl reaction by the AgNPs. In the presence of AβOs, Ad-PrP(95-110) interacted specifically with the AβOs, thus losing the capability to bind AgNPs and to induce the formation of an AgNPs-based network on the electrode surface. Consequently, the electrochemical signal decreased with an increase in the concentration of AβOs in the range of 20 pM to 100 nM. The biosensor had a detection limit of 8 pM and showed no response to amyloid-β monomers (AβMs) and fibrils (AβFs). On the basis of the well-defined and amplified electrochemical signal of the AgNPs-based network architecture, these results should be valuable for the design of novel electrochemical biosensors by marrying specific receptors.

  14. Microfluidic chip integrated with flexible PDMS-based electrochemical cytosensor for dynamic analysis of drug-induced apoptosis on HeLa cells.

    Science.gov (United States)

    Cao, Jun-Tao; Zhu, Ying-Di; Rana, Rohit Kumar; Zhu, Jun-Jie

    2014-01-15

    A novel microfluidic platform integrated with a flexible PDMS-based electrochemical cytosensor was developed for real-time monitoring of the proliferation and apoptosis of HeLa cells. The PDMS-gold film, which had a conductive smooth surface and was semi-transparent, facilitated electrochemical measurements and optical microscope observations. We observed distinct increases and decreases in peak current intensity, corresponding to cell proliferation in culture medium and apoptosis in the presence of an anticancer drug, respectively. This electrochemical analysis method permitted real-time, label-free monitoring of cell behavior, and the electrochemical results were confirmed with optical microscopy. The flexible microfluidic electrochemical platform presented here is suitable for on-site monitoring of cell behavior in microenvironments.

  15. Specific and Sensitive Isothermal Electrochemical Biosensor for Plant Pathogen DNA Detection with Colloidal Gold Nanoparticles as Probes

    Science.gov (United States)

    Lau, Han Yih; Wu, Haoqi; Wee, Eugene J. H.; Trau, Matt; Wang, Yuling; Botella, Jose R.

    2017-01-01

    Developing quick and sensitive molecular diagnostics for plant pathogen detection is challenging. Herein, a nanoparticle based electrochemical biosensor was developed for rapid and sensitive detection of plant pathogen DNA on disposable screen-printed carbon electrodes. This 60 min assay relied on the rapid isothermal amplification of target pathogen DNA sequences by recombinase polymerase amplification (RPA) followed by gold nanoparticle-based electrochemical assessment with differential pulse voltammetry (DPV). Our method was 10,000 times more sensitive than conventional polymerase chain reaction (PCR)/gel electrophoresis and could readily identify P. syringae infected plant samples even before the disease symptoms were visible. On the basis of the speed, sensitivity, simplicity and portability of the approach, we believe the method has potential as a rapid disease management solution for applications in agriculture diagnostics.

  16. Detection of the oxygen consumption rate of migrating zebrafish by electrochemical equalization systems.

    Science.gov (United States)

    Yasukawa, Tomoyuki; Koide, Masahiro; Tatarazako, Norihisa; Abe, Ryoko; Shiku, Hitoshi; Mizutani, Fumio; Matsue, Tomokazu

    2014-01-07

    A novel measurement system to determine oxygen consumption rates via respiration in migrating Zebrafish (Danio rerio) has been developed. A signal equalization system was adapted to detect oxygen in a chamber with one fish, because typical electrochemical techniques cannot measure respiration activities for migrating organisms. A closed chamber was fabricated using a pipet tip attached to a Pt electrode, and a columnar Vycor glass tip was used as the salt bridge. Pt electrode, which was attached to the chamber with one zebrafish, and Ag electrode were immersed in 10 mM potassium iodide (KI), and both the electrodes were connected externally to form a galvanic cell. Pt and Ag electrodes act as the cathode and anode to reduce oxygen and oxidize silver, respectively, allowing the deposition of insoluble silver iodide (AgI). The AgI acts as the signal source accumulated on the Ag electrode by conversion of oxygen. The amount of AgI deposited on the Ag electrode was determined by cathodic stripping voltammetry. The presence of zebrafish or its embryo led to a decrease in the stripping currents generated by a 10 min conversion of oxygen to AgI. The conversion of oxygen to AgI is disturbed by the migration of the zebrafish and allows the detection of different equalized signals corresponding to respiration activity. The oxygen consumption rates of the zebrafish and its embryo were estimated and determined to be ∼4.1 and 2.4 pmol·s(-1), respectively. The deposited AgI almost completely disappeared with a single stripping process. The signal equalization system provides a method to determine the respiration activities for migrating zebrafish and could be used to estimate environmental risk and for effective drug screening.

  17. Electrochemical detection of HbA1c, a marker [correction of maker] for diabetes, using a flow immunoassay system.

    Science.gov (United States)

    Tanaka, Tsuyoshi; Tsukube, Shoko; Izawa, Kojiro; Okochi, Mina; Lim, Tae-Kyu; Watanabe, Shugo; Harada, Manabu; Matsunaga, Tadashi

    2007-04-15

    An on-chip electrochemical flow immunoassay system for the detection of hemoglobin A1c (HbA1c) was developed using anti-human hemoglobin (Hb) IgG labeled with ferrocene monocarboxylic acid (Fc-COOH) and boronate-affinity chromatography. An on-chip column packed with boronate-activated agarose beads was used for the separation of HbA1c from both non-glycated Hb and free antibody. Anti-human Hb IgG conjugated to Fc-COOH (Fc-IgG) was used for the electrochemical detection of HbA1c. The assay procedure included immunoreactions with Fc-IgG and HbA1c, separation of immunocomplexes by boronate affinity, and electrochemical detection of Fc-IgG-HbA1c immunocomplexes. The immunoreaction mixtures were injected onto a boronate-affinity column. HbA1c-antibody complexes were then trapped onto the column by the affinity of HbA1c to boronic acid. Subsequently, elution buffer containing sorbitol was applied to elute HbA1c-antibody complexes and a current was detected by applying 600 mV versus Ag/AgCl. The elution signal was an estimation of the HbA1c amount. A linear correlation between the increase of current and HbA1c concentration was obtained up to an HbA1c concentration of 500 microg/ml. The HbA1c flow immunoassay was successfully achieved using hemolysates. This electrochemical flow immunoassay system enabled us to construct a novel point-of-care testing device for the monitoring of glycated proteins including HbA1c.

  18. Dendrimer-encapsulated copper as a novel oligonucleotides label for sensitive electrochemical stripping detection of DNA hybridization.

    Science.gov (United States)

    Gao, Huan; Jiang, Xue; Dong, Yang-Jun; Tang, Wan-Xin; Hou, Cong; Zhu, Ning-Ning

    2013-10-15

    This paper describes the synthesis and characterization of a novel electrochemical label for sensitive electrochemical stripping detection of DNA hybridization based on dendrimer-encapsulated copper. The generation 4.5 (G 4.5) carboxyl-terminated poly(amidoamine) dendrimer with a trimesyl core was used as a template for synthesis of Cu²⁺/dendrimer nanocomposites (Cu-DNCs). Ratios of Cu²⁺/dendrimer were optimized in order to obtain stable nanocomposites with maximal copper loading in the interior of a polymeric shell. Cu-DNCs labeled DNA probe was employed for determining a target ssDNA immobilized on multi-walled carbon nanotubes-modified glassy carbon electrode (GCE) based on a specific hybridization reaction. The hybridization events were monitored by electrochemical detection of Cu anchored on the hybrids after the release in a diluted nitric acid by anodic stripping differential pulse voltammetry (ASDPV). The results showed that only a complementary sequence could form a dsDNA with the Cu-DNCs DNA probe and give an obvious electrochemical signal. The non-complementary sequence exhibited negligible signal change compared with the blank measurement (means: the electrode containing no target DNA incubating in hybridization buffer solution containing Cu-DNCs DNA probe for a certain time). The use of Cu encapsulated-dendrimer as tags and ASDPV for the detection of the released Cu ions could enhance the hybridization signal, and result in the increase of the sensitivity for the target DNA. Under the conditions employed here, the detection limit for measuring the full complementary sequence is down to pM level. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Electrochemical DNA biosensor for detection of porcine oligonucleotides using ruthenium(II) complex as intercalator label redox

    Energy Technology Data Exchange (ETDEWEB)

    Halid, Nurul Izni Abdullah; Hasbullah, Siti Aishah; Heng, Lee Yook; Karim, Nurul Huda Abd [School of Chemical Sciences and Food Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan (Malaysia); Ahmad, Haslina; Harun, Siti Norain [Chemistry Department, Faculty of Science, Universiti Putra Malaysia, 43400, Serdang, Selangor (Malaysia)

    2014-09-03

    A DNA biosensor detection of oligonucleotides via the interactions of porcine DNA with redox active complex based on the electrochemical transduction is described. A ruthenium(II) complex, [Ru(bpy){sub 2}(PIP)]{sup 2+}, (bpy = 2,2′bipyridine, PIP = 2-phenylimidazo[4,5-f[[1,10-phenanthroline]) as DNA label has been synthesized and characterized by 1H NMR and mass spectra. The study was carried out by covalent bonding immobilization of porcine aminated DNA probes sequences on screen printed electrode (SPE) modified with succinimide-acrylic microspheres and [Ru(bpy){sub 2}(PIP)]{sup 2+} was used as electrochemical redox intercalator label to detect DNA hybridization event. Electrochemical detection was performed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) over the potential range where the ruthenium (II) complex was active. The results indicate that the interaction of [Ru(bpy){sub 2}(PIP)]{sup 2+} with hybridization complementary DNA has higher response compared to single-stranded and mismatch complementary DNA.

  20. 4-Fluoro-3-nitrophenyl grafted gold electrode based platform for label free electrochemical detection of interleukin-2 protein.

    Science.gov (United States)

    Arya, Sunil K; Park, Mi Kyoung

    2014-11-15

    A new platform based on 4-Fluoro-3-nitrophenyl (FNP) grafted gold disk electrode prepared via electrochemical reduction of 4-fluoro-3-nitrobenzene diazonium ion has been developed and utilized for biosensor fabrication. Anti-interleukin-2 (anti-IL2) antibody has been covalently immobilized onto FNP/Au surface and utilized for label free electrochemical impedance based detection of cytokine IL2. FNP acts as a bridge (cross-linker) between gold surface and anti-IL2, where fluoro group of FNP undergoes nucleophilic substitution by amino group of biomolecule and results in its covalent immobilization. The immobilization process and fabricated electrode have been characterized using contact angle (CA) measurements, cyclic voltammetry (CV) and electrochemical impedance (EIS) technique. CV studies show that FNP grafted surface provides conductive surface for anti-IL2 immobilization. The EIS response of studies as a function of IL2 concentrations exhibits a detection in linear range from 1 pg ml(-1) to 10 ng ml(-1) with minimum detectable concentration of 1 pg ml(-1). The electrode has been found to be selective against other cytokine molecules.

  1. Fast differentiation of meats from fifteen animal species by liquid chromatography with electrochemical detection using copper nanoparticle plated electrodes.

    Science.gov (United States)

    Chou, Chi-Chung; Lin, Show-Ping; Lee, Kuo-Ming; Hsu, Cheng-Teng; Vickroy, Thomas W; Zen, Jyh-Myng

    2007-02-01

    A simple, rapid and reliable method based on high-performance liquid chromatography with electrochemical detection was developed to routinely differentiate among meat products from fifteen food animal species. Samples from cattle, pigs, goats, deer, horses, chickens, ducks, ostriches, salmon, cod, shrimp, crabs, scallops, bullfrogs and alligators each exhibited unique electrochemical profiles. Species-specific markers exhibited reproducible peak retention times with coefficients of variation less then 6% across different runs, body regions and subjects. The method requires no derivatization or extraction steps and may be applicable to fresh or cooked meats. Incubation of fresh beef, pork or chicken at room temperature for 24h or repeated freezing and thawing changed the intensity but not the pattern of species-specific peaks. In conclusion, this method appears suitable for rapid differentiation of meats from various food animal species and demonstrates the utility of electrochemical detection to supplement existing immunochemical and molecular biological methods. The possibility of using this method to detect adulteration and degradative changes of meat proteins is discussed.

  2. Innovative approach for the electrochemical detection of non-electroactive organophosphorus pesticides using oxime as electroactive probe

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Jing; Hou, Juying; Jiang, Jianxia; Ai, Shiyun, E-mail: ashy@sdau.edu.cn

    2015-07-23

    Highlights: • Novel approach for electrochemical detection of non-electroactive OPs was proposed. • PAM was used as electroactive probe for the first time. • The detection system displayed high sensitivity and promptness. • The developed sensor was used in real samples with satisfactory results. - Abstract: An innovative approach for sensitive and simple electrochemical detection of non-electroactive organophosphorus pesticides (OPs) was described in this report. The novel strategy emphasized the fabrication of an oxime-based sensor via attaching pralidoxime (PAM) on graphene quantum dots (GQDs) modified glassy carbon electrode. The introduction of GQDs significantly increased the effective electrode area, and then enlarged the immobilization quantity of PAM. Thus, the oxidation current of PAM was obviously increased. Relying on the nucleophilic substitution reaction between oxime and OPs, fenthion was detected using PAM as the electroactive probe. Under optimum conditions, the difference of oxidation current of PAM was proportional to fenthion concentration over the range from 1.0 × 10{sup −11} M to 5.0 × 10{sup −7} M with a detection limit of 6.8 × 10{sup −12} M (S/N = 3). Moreover, the favorable detection performance in water and soil samples heralded the promising applications in on-site OPs detection.

  3. Electrochemical genosensor array for the simultaneous detection of multiple high-risk human papillomavirus sequences in clinical samples

    Energy Technology Data Exchange (ETDEWEB)

    Civit, Laia [Nanobiotechnology and Bioanalysis Group, Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, 43007 Tarragona (Spain); Fragoso, Alex, E-mail: alex.fragoso@urv.cat [Nanobiotechnology and Bioanalysis Group, Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, 43007 Tarragona (Spain); Hoelters, Sebastian; Duerst, Matthias [Department for Gynecology, Jena University Hospital, Friedrich-Schiller-University Jena, D-07743 Jena (Germany); O' Sullivan, Ciara K., E-mail: ciara.osullivan@urv.cat [Nanobiotechnology and Bioanalysis Group, Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, 43007 Tarragona (Spain); Institucio Catalana de Recerca i Estudis Avancats, Passeig Lluis Companys 23, 08010 Barcelona (Spain)

    2012-02-17

    Highlights: Black-Right-Pointing-Pointer High-risk human papillomavirus is detected in virtually all-invasive cervical cancers. Black-Right-Pointing-Pointer Electrochemical genosensor for simultaneous detection of multiple high-risk HPV applied to cervical scrape samples. Black-Right-Pointing-Pointer Excellent correlation with HPV genotyping carried out within a hospital laboratory. - Abstract: An electrochemical genosensor array for the simultaneous detection of three high-risk human papillomavirus (HPV) DNA sequences, HPV16, 18 and 45, exhibiting high sensitivity and selectivity is presented. The electrodes of a 4 Multiplication-Sign 4 array were modified via co-immobilization of a 1:100 (mol/mol) mixture of a thiolated probe and an oligoethyleneglycol-terminated bipodal thiol. Detection of synthetic and PCR products was carried out in a sandwich type format, with the target hybridized between a surface immobilized probe and a horseradish peroxidase-labelled secondary reporter probe. The detection limits obtained in the detection of each individual target were in the pM range, allowing the application of this sensor for the detection of samples obtained from PCR amplification of cervical scrape samples. The results obtained exhibited an excellent correlation with the HPV genotyping carried out within a hospital laboratory. Multiplexing and cross-reactivity studies demonstrated high selectivity over potential interfering sequences, facilitating application of the developed platform for the high-throughput screening of multiple high-risk DNA sequences.

  4. Enhancing graphene/CNT based electrochemical detection using magneto-nanobioprobes

    OpenAIRE

    sprotocols

    2015-01-01

    Authors: Priyanka Sharma, V Bhalla, E Senthil Prasad, V Dravid, G Shekhawat & C. Raman Suri ### Abstract This protocol describes an optimized signal amplification strategy to develop an ultra-sensitive magneto-electrochemical biosensing platform. The new protocol combines the advantages of carbon nanotube (CNT) and reduced graphene oxide (rGO) together with electrochemical bursting of magnetic nanoparticles. The method involves synthesis of gold-iron (Au/Fe) nano-structures func...

  5. Enhancing graphene/CNT based electrochemical detection using magneto-nanobioprobes

    OpenAIRE

    sprotocols

    2015-01-01

    Authors: Priyanka Sharma, V Bhalla, E Senthil Prasad, V Dravid, G Shekhawat & C. Raman Suri ### Abstract This protocol describes an optimized signal amplification strategy to develop an ultra-sensitive magneto-electrochemical biosensing platform. The new protocol combines the advantages of carbon nanotube (CNT) and reduced graphene oxide (rGO) together with electrochemical bursting of magnetic nanoparticles. The method involves synthesis of gold-iron (Au/Fe) nano-structures func...

  6. Microscale electrodes integrated on COP for real sample Campylobacter spp. detection.

    Science.gov (United States)

    Morant-Miñana, M Carmen; Elizalde, J

    2015-08-15

    Campylobacter spp. are responsible for acute bacterial diseases in human worldwide. Nowadays campilobacteriosis is considered the most common foodborne illness in the European Union. In this paper the first electrochemical genosensor based on thin-film gold electrodes deposited onto Cyclo Olefin Polymer (COP) substrates was fabricated for the detection of Campylobacter spp in food matrices. The sensing element is characterized by several surface techniques and the sensitivity of the biosensor have been studied. A good linear relationship was obtained for the concentrations of PCR amplicon of Campylobacter spp. between 1 and 25 nM with a limit of detection (LOD) of 90 pM. Real samples have been validated with poultry meat samples and results were comparable with the PCR product samples. This is the last step for the fabrication of a Lab on a Chip (LOC), a biodevice integrating DNA sensor technology into microfluidic system, believed to perform an automated and complete assay, including sample preparation, PCR amplification, and electrochemical detection of Campylobacter spp. in raw poultry meat samples.

  7. An integrated platform for gas-diffusion separation and electrochemical determination of ethanol on fermentation broths

    Energy Technology Data Exchange (ETDEWEB)

    Giordano, Gabriela Furlan [Microfabrication Laboratory, Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP 13083-970 (Brazil); Department of Analytical Chemistry, Institute of Chemistry – UNICAMP, Campinas, SP 13083-970 (Brazil); National Institute of Science and Technology of Bioanalytics, Institute of Chemistry – UNICAMP, Campinas, SP 13083-970 (Brazil); Vieira, Luis Carlos Silveira; Gobbi, Angelo Luiz [Microfabrication Laboratory, Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP 13083-970 (Brazil); Lima, Renato Sousa [Microfabrication Laboratory, Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP 13083-970 (Brazil); Department of Analytical Chemistry, Institute of Chemistry – UNICAMP, Campinas, SP 13083-970 (Brazil); National Institute of Science and Technology of Bioanalytics, Institute of Chemistry – UNICAMP, Campinas, SP 13083-970 (Brazil); Kubota, Lauro Tatsuo, E-mail: kubota@iqm.unicamp.br [Department of Analytical Chemistry, Institute of Chemistry – UNICAMP, Campinas, SP 13083-970 (Brazil); National Institute of Science and Technology of Bioanalytics, Institute of Chemistry – UNICAMP, Campinas, SP 13083-970 (Brazil)

    2015-05-22

    Highlights: • Integrated platform was developed to determine ethanol in fermentation broths. • The designed system integrates gas diffusion separation with voltammetric detection. • Detector relied on Ni(OH){sub 2}-modified electrode stabilized by Co{sup 2+} and Cd{sup 2+} insertion. • Separation was made by PTFE membrane separating sample from electrolyte (receptor). • Despite the sample complexity, accurate tests were achieved by direct interpolation. - Abstract: An integrated platform was developed for point-of-use determination of ethanol in sugar cane fermentation broths. Such analysis is important because ethanol reduces its fuel production efficiency by altering the alcoholic fermentation step when in excess. The custom-designed platform integrates gas diffusion separation with voltammetric detection in a single analysis module. The detector relied on a Ni(OH){sub 2}-modified electrode. It was stabilized by uniformly depositing cobalt and cadmium hydroxides as shown by XPS measurements. Such tests were in accordance with the hypothesis related to stabilization of the Ni(OH){sub 2} structure by insertion of Co{sup 2+} and Cd{sup 2+} ions in this structure. The separation step, in turn, was based on a hydrophobic PTFE membrane, which separates the sample from receptor solution (electrolyte) where the electrodes were placed. Parameters of limit of detection and analytical sensitivity were estimated to be 0.2% v/v and 2.90 μA % (v/v){sup −1}, respectively. Samples of fermentation broth were analyzed by both standard addition method and direct interpolation in saline medium based-analytical curve. In this case, the saline solution exhibited ionic strength similar to those of the samples intended to surpass the tonometry colligative effect of the samples over analyte concentration data by attributing the reduction in quantity of diffused ethanol vapor majorly to the electrolyte. The approach of analytical curve provided rapid, simple and accurate

  8. Electrochemical construction

    Science.gov (United States)

    Einstein, Harry; Grimes, Patrick G.

    1983-08-23

    An electrochemical cell construction features a novel co-extruded plastic electrode in an interleaved construction with a novel integral separator-spacer. Also featured is a leak and impact resistant construction for preventing the spill of corrosive materials in the event of rupture.

  9. A digital microfluidic device with integrated nanostructured microelectrodes for electrochemical immunoassays.

    Science.gov (United States)

    Rackus, Darius G; Dryden, Michael D M; Lamanna, Julian; Zaragoza, Alexandre; Lam, Brian; Kelley, Shana O; Wheeler, Aaron R

    2015-01-01

    Nanostructured microelectrodes (NMEs) are three-dimensional electrodes that have superb sensitivity for electroanalysis. Here we report the integration of NMEs with the versatile fluid-handling system digital microfluidics (DMF), for eventual application to distributed diagnostics outside of the laboratory. In the new methods reported here, indium tin oxide DMF top plates were modified to include Au NMEs as well as counter and pseudoreference electrodes. The new system was observed to outperform planar sensing electrodes of the type that are typically integrated with DMF. A rubella virus (RV) IgG immunoassay was developed to evaluate the diagnostic potential for the new system, relying on magnetic microparticles coated with RV particles and analysis by differential pulse voltammetry. The limit of detection of the assay (0.07 IU mL(-1)) was >100× below the World Health Organization defined cut-off for rubella immunity. The sensitivity of the integrated device and its small size suggest future utility for distributed diagnostics.

  10. A bi-directional electrochemically driven micro liquid dosing system with integrated sensor/actuator electrodes

    NARCIS (Netherlands)

    Bohm, S.; Olthuis, Wouter; Bergveld, Piet

    2000-01-01

    In this contribution a micro liquid dosing system is presented, which allows bi-directional manipulation of fluids (i.e. pushing out and pulling in of liquids) by the electrochemical generation and removal of gas bubbles. Bi-directionality is obtained by reversal of the actuation current thereby

  11. Simultaneous Detection and Estimation of Catechol, Hydroquinone, and Resorcinol in Binary and Ternary Mixtures Using Electrochemical Techniques.

    Science.gov (United States)

    Hossain, Md Uzzal; Rahman, Md Toufiqur; Ehsan, Md Qamrul

    2015-01-01

    Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were performed with a glassy carbon electrode (GCE) modified with polyglutamic acid (PGA) on the three dihydroxybenzene isomers, catechol (CT), hydroquinone (HQ), and resorcinol (RS). At bare GCE, these isomers exhibited voltammograms with highly overlapped redox peaks that impeded their simultaneous detection in binary and ternary mixtures. On the contrary, at PGA modified GCE binary and ternary mixtures of the dihydroxybenzene isomers showed well-resolved redox peaks in both CV and DPV experiments. This resolving ability of PGA modified GCE proves its potential to be exploited as an electrochemical sensor for the simultaneous detection of these isomers.

  12. Simultaneous Detection and Estimation of Catechol, Hydroquinone, and Resorcinol in Binary and Ternary Mixtures Using Electrochemical Techniques

    Directory of Open Access Journals (Sweden)

    Md. Uzzal Hossain

    2015-01-01

    Full Text Available Cyclic voltammetry (CV and differential pulse voltammetry (DPV were performed with a glassy carbon electrode (GCE modified with polyglutamic acid (PGA on the three dihydroxybenzene isomers, catechol (CT, hydroquinone (HQ, and resorcinol (RS. At bare GCE, these isomers exhibited voltammograms with highly overlapped redox peaks that impeded their simultaneous detection in binary and ternary mixtures. On the contrary, at PGA modified GCE binary and ternary mixtures of the dihydroxybenzene isomers showed well-resolved redox peaks in both CV and DPV experiments. This resolving ability of PGA modified GCE proves its potential to be exploited as an electrochemical sensor for the simultaneous detection of these isomers.

  13. Label-free, electrochemical detection of methicillin-resistant staphylococcus aureus DNA with reduced graphene oxide-modified electrodes

    KAUST Repository

    Wang, Zhijuan

    2011-05-01

    Reduced graphene oxide (rGO)-modified glassy carbon electrode is used to detect the methicillin-resistant Staphylococcus aureus (MRSA) DNA by using electrochemical impedance spectroscopy. Our experiments confirm that ssDNA, before and after hybridization with target DNA, are successfully anchored on the rGO surface. After the probe DNA, pre-adsorbed on rGO electrode, hybridizes with target DNA, the measured impedance increases dramatically. It provides a new method to detect DNA with high sensitivity (10-13M, i.e., 100 fM) and selectivity. © 2011 Elsevier B.V.

  14. A Label-Free Electrochemical Immunosensor for Carbofuran Detection Based on a Sol-Gel Entrapped Antibody

    Directory of Open Access Journals (Sweden)

    Qingqing Li

    2011-10-01

    Full Text Available In this study, an anti-carbofuran monoclonal antibody (Ab was immobilized on the surface of a glassy carbon electrode (GCE using silica sol-gel (SiSG technology. Thus, a sensitive, label-free electrochemical immunosensor for the direct determination of carbofuran was developed. The electrochemical performance of immunoreaction of antigen with the anti-carbofuran monoclonal antibody was investigated by cyclic voltammetry (CV and electrochemical impedance spectroscopy (EIS, in which phosphate buffer solution containing [Fe(CN6]3−/4− was used as the base solution for test. Because the complex formed by the immunoreaction hindered the diffusion of [Fe(CN6]3−/4− on the electrode surface, the redox peak current of the immunosensor in the CV obviously decreased with the increase of the carbofuran concentration. The pH of working solution, the concentration of Ab and the incubation time of carbofuran were studied to ensure the sensitivity and conductivity of the immunosensor. Under the optimal conditions, the linear range of the proposed immunosensor for the determination of carbofuran was from 1 ng/mL to 100 μg/mL and from 50 μg/mL to 200 μg/mL with a detection limit of 0.33 ng/mL (S/N = 3. The proposed immunosensor exhibited good high sensitivity and stability, and it was thus suitable for trace detection of carbofuran pesticide residues.

  15. A label-free electrochemical immunosensor for carbofuran detection based on a sol-gel entrapped antibody.

    Science.gov (United States)

    Sun, Xia; Du, Shuyuan; Wang, Xiangyou; Zhao, Wenping; Li, Qingqing

    2011-01-01

    In this study, an anti-carbofuran monoclonal antibody (Ab) was immobilized on the surface of a glassy carbon electrode (GCE) using silica sol-gel (SiSG) technology. Thus, a sensitive, label-free electrochemical immunosensor for the direct determination of carbofuran was developed. The electrochemical performance of immunoreaction of antigen with the anti-carbofuran monoclonal antibody was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), in which phosphate buffer solution containing [Fe(CN)(6)](3-/4-) was used as the base solution for test. Because the complex formed by the immunoreaction hindered the diffusion of [Fe(CN)(6)](3-/4-) on the electrode surface, the redox peak current of the immunosensor in the CV obviously decreased with the increase of the carbofuran concentration. The pH of working solution, the concentration of Ab and the incubation time of carbofuran were studied to ensure the sensitivity and conductivity of the immunosensor. Under the optimal conditions, the linear range of the proposed immunosensor for the determination of carbofuran was from 1 ng/mL to 100 μg/mL and from 50 μg/mL to 200 μg/mL with a detection limit of 0.33 ng/mL (S/N = 3). The proposed immunosensor exhibited good high sensitivity and stability, and it was thus suitable for trace detection of carbofuran pesticide residues.

  16. CdSe/ZnS quantum dots based electrochemical immunoassay for the detection of phosphorylated bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Pinwattana, Kulwadee; Wang, Jun; Lin, Chiann Tso; Wu, Hong; Du, Dan; Lin, Yuehe; Chailapakul, Orawon

    2010-11-15

    A CdSe/ZnS quantum dot (QD) based electrochemical immunoassay of phosphorylated bovine serum albumin as a protein biomarker is presented. The QDs were used as labels and were conjugated with the secondary anti-phosphoserine antibody in a heterogeneous sandwich immunoassay. First, the primary BSA antibody was immobilized on polystyrene microwells, followed by the addition of BSA-OP. After that, the QD-labeled anti-phosphoserine antibody was added into microwells for immunorecognition. Finally, the bound QD was dissolved in an acid-dissolution step and was detected by electrochemical stripping analysis. The measured current responses were proportional to the concentration of BSA-OP. Under optimal conditions, the voltammetric response was linear over the range of 0.5 - 500 ng mL-1 of BSA-OP, with a detection limit of 0.5 ng mL-1 at a deposition potential of -1.2 V for 120 s. It also shows good reproducibility with a relative standard deviation of 8.6% of six times determination of 25 ng mL-1 of BSA-OP. This QD-based electrochemical immunoassay offers great promise for simple and cost-effective analysis of protein biomarkers.

  17. Dual-responsive immunosensor that combines colorimetric recognition and electrochemical response for ultrasensitive detection of cancer biomarkers.

    Science.gov (United States)

    Hong, Wooyoung; Lee, Sooyeon; Cho, Youngnam

    2016-12-15

    We developed a nanoroughened, biotin-doped polypyrrole immunosensor for the detection of tumor markers through dual-signal (electrochemical and colorimetric) channels, electrochemical and colorimetric, that demonstrates remarkable analytical performance. A rapid, one-step electric field-mediated method was employed to fabricate the immunosensor with nanoscale roughness by simply modulating the applied electrical potential. We demonstrated the successful detection of three tumor markers (CA125, CEA, and PSA) via the double enzymatic signal amplifications in the presence of a target antigen, ultimately leading to desired diagnostic accuracy and reliability. The addition of multiple horseradish peroxidase (HRP)- and antibody-labeled nanoparticles greatly amplified the signal and simplified the measurement of cancer biomarker proteins by sequentially magnifying electrochemical and colorimetric signals in a single platform. The two parallel assays performed using the proposed immunosensor have yielded highly consistent and reproducible results. Additionally, for the analysis of plasma samples in a clinical setting, the values obtained with our immunosensor were validated by correlating the results with those of a standard radioimmunoassay (RIA), which obtained very similar clinically valid responses.

  18. Electroless deposition of Au nanoparticles on reduced graphene oxide/polyimide film for electrochemical detection of hydroquinone and catechol

    Science.gov (United States)

    Shen, Xuan; Xia, Xiaohong; Du, Yongling; Wang, Chunming

    2017-09-01

    An electrochemical sensor for determination of hydroquinone (HQ) and catechol (CC) was developed using Au nanoparticles (AuNPs) fabricated on reduced graphene oxide/polyimide (PI/RGO) film by electroless deposition. The electrochemical behaviors of HQ and CC at PI/RGO-AuNPs electrode were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Under the optimized condition, the current responses at PI/RGO-AuNPs electrode were linear over ranges from 1 to 654 mol/L for HQ and from 2 to 1289 mol/L for CC, with the detection limits of 0.09 and 0.2 mol/L, respectively. The proposed electrode exhibited good reproducibility, stability and selectivity. In addition, the proposed electrode was successfully applied in the determination of HQ and CC in tap water and the Yellow River samples.

  19. Single electrode electrochemical detection in hybrid poly(dimethylsiloxane)/glass multichannel micro devices

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Ney Henrique; Almeida, Andre Luis de Jesus de; Piazzeta, Maria Helena de Oliveira; Gobbia, Angelo Luiz [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas, SP (Brazil). Lab. de Microfabricacao; Jesus, Dosil Pereira de [Instituto Nacional de Ciencia e Tecnologia em Bioanalitica (INCTBio), Campinas, SP (Brazil); Deblire, Ariane; Silva, Jose Alberto Fracassi da [Universidade Estadual de Campinas (IQ/UNICAMP), SP (Brazil). Inst. de Quimica

    2009-07-01

    The fabrication process of a novel multichannel {mu}TAS based on PDMS and glass materials and with fully-integrated electrodes for amperometric detection has been described. Using the facilities of the Microfabrication Lab. (LMF) at Brazilian Synchrotron Light Laboratory (LNLS), soft-lithography, lift-off and O{sub 2} plasma surface activation sealing techniques were employed for rapid proto typing of cost effective PDMS/glass microchips. Fast calibration procedures were possible for the electro oxidation of hydroquinone, thiocyanate, and acetaminophen using Au and Cu electrodes. (author)

  20. Specific Magnetic Isolation of E6 HPV16 Modified Magnetizable Particles Coupled with PCR and Electrochemical Detection.

    Science.gov (United States)

    Jimenez Jimenez, Ana Maria; Ruttkay-Nedecky, Branislav; Dostalova, Simona; Krejcova, Ludmila; Michalek, Petr; Richtera, Lukas; Adam, Vojtech

    2016-05-05

    The majority of carcinomas that were developed due to the infection with human papillomavirus (HPV) are caused by high-risk HPV types, HPV16 and HPV18. These HPV types contain the E6 and E7 oncogenes, so the fast detection of these oncogenes is an important point to avoid the development of cancer. Many different HPV tests are available to detect the presence of HPV in biological samples. The aim of this study was to design a fast and low cost method for HPV identification employing magnetic isolation, polymerase chain reaction (PCR) and electrochemical detection. These assays were developed to detect the interactions between E6-HPV16 oncogene and magnetizable particles (MPs) using commercial Dynabeads M-280 Streptavidin particles and laboratory-synthesized "homemade" particles called MANs (MAN-37, MAN-127 and MAN-164). The yields of PCR amplification of E6-HPV16 oncogene bound on the particles and after the elution from the particles were compared. A highest yield of E6-HPV16 DNA isolation was obtained with both MPs particles commercial M-280 Streptavidin and MAN-37 due to reducing of the interferents compared with the standard PCR method. A biosensor employing the isolation of E6-HPV16 oncogene with MPs particles followed by its electrochemical detection can be a very effective technique for HPV identification, providing simple, sensitive and cost-effective analysis.

  1. Specific Magnetic Isolation of E6 HPV16 Modified Magnetizable Particles Coupled with PCR and Electrochemical Detection

    Directory of Open Access Journals (Sweden)

    Ana Maria Jimenez Jimenez

    2016-05-01

    Full Text Available The majority of carcinomas that were developed due to the infection with human papillomavirus (HPV are caused by high-risk HPV types, HPV16 and HPV18. These HPV types contain the E6 and E7 oncogenes, so the fast detection of these oncogenes is an important point to avoid the development of cancer. Many different HPV tests are available to detect the presence of HPV in biological samples. The aim of this study was to design a fast and low cost method for HPV identification employing magnetic isolation, polymerase chain reaction (PCR and electrochemical detection. These assays were developed to detect the interactions between E6-HPV16 oncogene and magnetizable particles (MPs using commercial Dynabeads M-280 Streptavidin particles and laboratory-synthesized “homemade” particles called MANs (MAN-37, MAN-127 and MAN-164. The yields of PCR amplification of E6-HPV16 oncogene bound on the particles and after the elution from the particles were compared. A highest yield of E6-HPV16 DNA isolation was obtained with both MPs particles commercial M-280 Streptavidin and MAN-37 due to reducing of the interferents compared with the standard PCR method. A biosensor employing the isolation of E6-HPV16 oncogene with MPs particles followed by its electrochemical detection can be a very effective technique for HPV identification, providing simple, sensitive and cost-effective analysis.

  2. A novel label-free microfluidic paper-based immunosensor for highly sensitive electrochemical detection of carcinoembryonic antigen.

    Science.gov (United States)

    Wang, Yang; Xu, Huiren; Luo, Jinping; Liu, Juntao; Wang, Li; Fan, Yan; Yan, Shi; Yang, Yue; Cai, Xinxia

    2016-09-15

    In this work, a highly sensitive label-free paper-based electrochemical immunosensor employing screen-printed working electrode (SPWE) for detection of carcinoembryonic antigen (CEA) was fabricated. In order to raise the detection sensitivity and immobilize anti-CEA, amino functional graphene (NH2-G)/thionine (Thi)/gold nanoparticles (AuNPs) nanocomposites were synthesized and coated on SPWE. The principle of the immunosensor determination was based on the fact that the decreased response currents of Thi were proportional to the concentrations of corresponding antigens due to the formation of antibody-antigen immunocomplex. Experimental results revealed that the immunoassay enabled the determination of standard CEA solutions with linear working ranges of 50pgmL(-1) to 500ngmL(-1), the limit of detections for CEA is 10pgmL(-1) (S/N=3) and its corresponding correlation coefficients were 0.996. Furthermore, the proposed immunosensor could be used for the determination of clinical serum samples. A large number of clinical serum samples were detected and the relative errors between measured values and reference concentrations were calculated. Results showed that this novel paper-based electrochemical immunosensor could provide a new platform for low cost, sensitive, specific, and point-of-care diagnosis in cancer detection.

  3. Detection of ESAT-6 by a label free miniature immuno-electrochemical biosensor as a diagnostic tool for tuberculosis.

    Science.gov (United States)

    Diouani, Mohamed Fethi; Ouerghi, Oussama; Refai, Amira; Belgacem, Kamel; Tlili, Chaker; Laouini, Dhafer; Essafi, Makram

    2017-05-01

    Tuberculosis is a worldwide disease considered as a major health problem with high morbidity and mortality rates. Poor detection of Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis remains a major obstacle to the global control of this disease. Here we report the development of a new test based on the detection of the major virulent factor of Mtb, namely the early secreted antigenic target 6-kDa protein or ESAT-6. A label free electrochemical immunosensor using an anti-ESAT-6 monoclonal antibody as a bio-receptor is described herein. Anti-ESAT-6 antibodies were first covalently immobilized on the surface of a gold screen-printed electrode functionalized via a self-assembled thiol monolayer. Interaction between the bio-receptor and ESAT-6 antigen was evaluated by square wave voltammetry method using [Fe(CN)6](3-/4-) as redox probe. The detection limit of ESAT-6 antigen was 7ng/ml. The immunosensor has also been able to detect native ESAT-6 antigen secreted in cell culture filtrates of three pathogenic strains of Mtb (CDC1551, H37RV and H8N8). Overall, this work describes an immune-electrochemical biosensor, based on ESAT-6 antigen detection, as a useful diagnostic tool for tuberculosis. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. A novel electrochemical aptasensor based on single-walled carbon nanotubes, gold electrode and complimentary strand of aptamer for ultrasensitive detection of cocaine.

    Science.gov (United States)

    Taghdisi, Seyed Mohammad; Danesh, Noor Mohammad; Emrani, Ahmad Sarreshtehdar; Ramezani, Mohammad; Abnous, Khalil

    2015-11-15

    Cocaine is a strong central nervous system stimulant and one of the most commonly abused drugs. In this study, an electrochemical aptasensor was designed for sensitive and selective detection of cocaine, based on single-walled carbon nanotubes (SWNTs), gold electrode and complimentary strand of aptamer (CS). This electrochemical aptasensor inherits properties of SWNTs and gold such as large surface area and high electrochemical conductivity, as well as high affinity and selectivity of aptamer toward its target and the stronger interaction of SWNTs with single-stranded DNA (ssDNA) than double-stranded DNA (dsDNA). In the absence of cocaine, a little amount of SWNTs bind to Aptamer-CS-modified electrode, so that the electrochemical signal is weak. In the presence of cocaine, aptamer binds to cocaine, leaves the surface of electrode. So that, a large amount of SWNTs bind to CS-modified electrode, generating to a strong electrochemical signal. The designed electrochemical aptasensor showed good selectivity toward cocaine with a limit of detection (LOD) as low as 105 pM. Moreover, the fabricated electrochemical aptasensor was successfully applied to detect cocaine in serum with a LOD as low as 136 pM.

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

    Science.gov (United States)

    Palanisamy, Selvakumar; Thirumalraj, Balamurugan; Chen, Shen-Ming; Wang, Yi-Ting; Velusamy, Vijayalakshmi; Ramaraj, Sayee Kannan

    2016-09-01

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

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

    Science.gov (United States)

    Palanisamy, Selvakumar; Thirumalraj, Balamurugan; Chen, Shen-Ming; Wang, Yi-Ting; Velusamy, Vijayalakshmi; Ramaraj, Sayee Kannan

    2016-01-01

    We report a novel and sensitive amperometric sensor for chlorpromazine (CPZ) based on reduced graphene oxide (RGO) and polydopamine (PDA) composite modified glassy carbon electrode. The RGO@PDA composite was prepared by electrochemical reduction of graphene oxide (GO) with PDA. The RGO@PDA composite modified electrode shows an excellent electro-oxidation behavior to CPZ when compared with other modified electrodes such as GO, RGO and GO@PDA. Amperometric i-t method was used for the determination of CPZ. Amperometry result shows that the RGO@PDA composite detects CPZ in a linear range from 0.03 to 967.6 μM. The sensor exhibits a low detection limit of 0.0018 μM with the analytical sensitivity of 3.63 ± 0.3 μAμM–1 cm–2. The RGO@PDA composite shows its high selectivity towards CPZ in the presence of potentially interfering drugs such as metronidazole, phenobarbital, chlorpheniramine maleate, pyridoxine and riboflavin. In addition, the fabricated RGO@PDA modified electrode showed an appropriate recovery towards CPZ in the pharmaceutical tablets. PMID:27650697

  7. A novel LTCC electrochemical cell construction and characterization: a detection compartment for portable devices.

    Science.gov (United States)

    Pesquero, Naira Canevarolo; Gongora-Rubio, Mário Ricardo; Yamanaka, Hideko

    2013-08-07

    In this work we described for the first time the construction of a 25 μL electrochemical cell from low temperature co-fired ceramic (LTCC) material and carbon screen-printed electrode applicable in portable devices. Firstly, a carbon screen-printed electrode was prepared and characterized by cyclic voltammetry and scanning electron microscopy. Afterwards carbon polymeric film and metal pastes were dropped into the LTCC cell cavities in order to determine the device electrodes, and this arrangement was also electrochemically characterized. The great advantage of this promising device is the simple construction method and its widespread applicability in reusable portable devices.

  8. Detecting transforming growth factor-β release from liver cells using an aptasensor integrated with microfluidics.

    Science.gov (United States)

    Matharu, Zimple; Patel, Dipali; Gao, Yandong; Haque, Amranul; Zhou, Qing; Revzin, Alexander

    2014-09-02

    We developed a cell-culture/biosensor platform consisting of aptamer-modified Au electrodes integrated with reconfigurable microfluidics for monitoring of transforming growth factor-beta 1 (TGF-β1), an important inflammatory and pro-fibrotic cytokine. Aptamers were thiolated, labeled with redox reporters, and self-assembled on gold surfaces. The biosensor was determined to be specific for TGF-β1 with an experimental detection limit of 1 ng/mL and linear range extending to 250 ng/mL. Upon determining figures of merit, aptasensor was miniaturized and integrated with human hepatic stellate cells inside microfluidic devices. Reconfigurable microfluidics were developed to ensure that seeding of "sticky" stromal cells did not foul the electrode and compromise sensor performance. This microsystem with integrated aptasensors was used to monitor TGF-β1 release from activated stellate cells over the course of 20 h. The electrochemical response went down upon infusing anti-TGF-β1 antibodies into the microfluidic devices containing activated stellate cells. To further validate aptasensor responses, stellate cells were stained for markers of activation (e.g., alpha smooth muscle actin) and were also tested for presence of TGF-β1 using enzyme linked immunosorbent assay (ELISA). Given the importance of TGF-β1 as a fibrogenic signal, a microsystem with integrated biosensors for local and continuous detection of TGF-β1 may prove to be an important tool to study fibrosis of the liver and other organs.

  9. Ultrasensitive nanostructure sensor arrays on flexible substrates for multiplexed and simultaneous electrochemical detection of a panel of cardiac biomarkers.

    Science.gov (United States)

    Radha Shanmugam, Nandhinee; Muthukumar, Sriram; Chaudhry, Shajee; Anguiano, Jonathan; Prasad, Shalini

    2017-03-15

    Multiplexed detection of protein biomarkers offers new opportunities for early diagnosis and efficient treatment of complex diseases. Cardiovascular diseases (CVDs) has the highest mortality risk in USA and Europe with 15-20 million cases being reported annually. Cardiac Troponins (T and I) are well established protein biomarkers associated with heart muscle damage and point-of-care monitoring of both these two biomarkers has significant benefits on patient care. A flexible disposable electrochemical biosensor device comprising of vertically oriented zinc oxide (ZnO) nanostructures was developed for rapid and simultaneous screening of cardiac Troponin-I (cTnI) and cardiac-Troponin-T (cTnT) in a point-of-care sensor format. The biosensors were designed by selective hydrothermal growth of ZnO nanostructures onto the working electrodes of polyimide printed circuit board platforms, resulting in the generation of high density nanostructure ZnO arrays based electrodes. The size, density and surface terminations of the nanostructures were leveraged towards achieving surface confinement of the target cTnT and cTnI molecules on to the electrode surface. Multiplexing and simultaneous detection was achieved through sensor platform design comprising of arrays of Troponin functionalized ZnO nanostructure electrodes. The sensitivity and specificity of the biosensor was characterized using two types of electrochemical techniques; electrochemical impedance spectroscopy (EIS) and Mott-Schottky analysis on the same sensor platform to demonstrate multi-configurable modes. Limit of detection of 1pg/mL in human serum was achieved for both cTnI and cTnT. Cross reactivity analysis showed the selectivity of detecting cTnT and cTnI in human serum with wide dynamic range.

  10. Ultrasensitive electrochemical aptasensor based on sandwich architecture for selective label-free detection of colorectal cancer (CT26) cells.

    Science.gov (United States)

    Hashkavayi, Ayemeh Bagheri; Raoof, Jahan Bakhsh; Ojani, Reza; Kavoosian, Saeid

    2017-06-15

    Colorectal cancer is one of the most common cancers in the world and has no effective treatment. Therefore, development of new methods for early diagnosis is instantly required. Biological recognition probes such as synthetic receptor and aptamer is one of the candidate recognition layers to detect important biomolecules. In this work, an electrochemical aptasensor was developed by fabricating an aptamer-cell-aptamer sandwich architecture on an SBA-15-3-aminopropyltriethoxysilane (SBA-15-pr-NH2) and Au nanoparticles (AuNPs) modified graphite screen printed electrode (GSPE) surface for the selective, label-free detection of CT26 cancer cells. Based on the incubation of the thiolated aptamer with CT26 cells, the electron-transfer resistance of Fe (CN)6(3-/4-) redox couple increased considerably on the aptasensor surface. The results obtained from cyclic voltammetry and electrochemical impedance spectroscopy studies showed that the fabricated aptasensor can specifically identify CT26 cells in the concentration ranges of 10-1.0×10(5)cells/mL and 1.0×10(5)-6.0×10(6) cells/mL, respectively, with a detection limit of 2cells/mL. Applying the thiol terminated aptamer (5TR1) as a recognition layer led to a sensor with high affinity for CT26 cancer cells, compared to control cancer cells of AGS cells, VERO Cells, PC3 cells and SKOV-3 cells. Therefore a simple, rapid, label free, inexpensive, excellent, sensitive and selective electrochemical aptasensor based on sandwich architecture was developed for detection of CT26 Cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Capture, isolation and electrochemical detection of industrially-relevant engineered aerosol nanoparticles using poly (amic) acid, phase-inverted, nano-membranes

    Energy Technology Data Exchange (ETDEWEB)

    Okello, Veronica A. [Department of Chemistry, Center for Advanced Sensors and Environmental Systems (CASE), State University of New York at Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States); Gass, Samuel; Pyrgiotakis, Georgios [Center for Nanotechnology and Nanotoxicology, Harvard School of Public Health, Department of Environmental Health, 665 Huntington Avenue, Boston, MA 02115-6021 (United States); Du, Nian; Lake, Andrew; Kariuki, Victor [Department of Chemistry, Center for Advanced Sensors and Environmental Systems (CASE), State University of New York at Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States); Sotiriou, Georgios A. [Center for Nanotechnology and Nanotoxicology, Harvard School of Public Health, Department of Environmental Health, 665 Huntington Avenue, Boston, MA 02115-6021 (United States); Addolorato, Jessica [Department of Chemistry, Center for Advanced Sensors and Environmental Systems (CASE), State University of New York at Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States); Demokritou, Philip, E-mail: pdemokri@hsph.harvard.edu [Center for Nanotechnology and Nanotoxicology, Harvard School of Public Health, Department of Environmental Health, 665 Huntington Avenue, Boston, MA 02115-6021 (United States); Sadik, Omowunmi A., E-mail: osadik@binghamton.edu [Department of Chemistry, Center for Advanced Sensors and Environmental Systems (CASE), State University of New York at Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States)

    2014-08-30

    Graphical abstract: - Highlights: • Exposure level assessment of aerosol nanoparticles reported using Harvard's VENGES. • Device equipped with pi-conjugated conducting PAA membrane filters/sensor arrays. • PAA membrane motifs used to capture, isolate and detect the nanoparticles. • Manipulating the PAA delocalized π electron enabled electrocatalytic detection. • Fe{sub 2}O{sub 3}, ZnO and TiO{sub 2} quantified using impedance spectroscopy and cyclic voltammetry. - Abstract: Workplace exposure to engineered nanoparticles (ENPs) is a potential health and environmental hazard. This paper reports a novel approach for tracking hazardous airborne ENPs by applying online poly (amic) acid membranes (PAA) with offline electrochemical detection. Test aerosol (Fe{sub 2}O{sub 3}, TiO{sub 2} and ZnO) nanoparticles were produced using the Harvard (Versatile Engineered Generation System) VENGES system. The particle morphology, size and elemental composition were determined using SEM, XRD and EDS. The PAA membrane electrodes used to capture the airborne ENPs were either stand-alone or with electron-beam gold-coated paper substrates. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to conceptually illustrate that exposure levels of industry-relevant classes of airborne nanoparticles could be captured and electrochemically detected at PAA membranes filter electrodes. CV parameters showed that PAA catalyzed the reduction of Fe{sub 2}O{sub 3} to Fe{sup 2+} with a size-dependent shift in reduction potential (E{sup 0}). Using the proportionality of peak current to concentration, the amount of Fe{sub 2}O{sub 3} was found to be 4.15 × 10{sup −17} mol/cm{sup 3} PAA electrodes. Using EIS, the maximum phase angle (Φ{sub max}) and the interfacial charge transfer resistance (R{sub ct}) increased significantly using 100 μg and 1000 μg of TiO{sub 2} and ZnO respectively. The observed increase in Φ{sub max} and R{sub ct} at increasing

  12. Development of a novel biosensor using cationic antimicrobial Peptide and nickel phthalocyanine ultrathin films for electrochemical detection of dopamine.

    Science.gov (United States)

    Zampa, Maysa F; Araújo, Inês Maria de S; Dos Santos Júnior, José Ribeiro; Zucolotto, Valtencir; Leite, José Roberto de S A; Eiras, Carla

    2012-01-01

    The antimicrobial peptide dermaseptin 01 (DS 01), from the skin secretion of Phyllomedusa hypochondrialis frogs, was immobilized in nanostructured layered films in conjunction with nickel tetrasulfonated phthalocyanines (NiTsPc), widely used in electronic devices, using layer-by-layer technique. The films were used as a biosensor to detect the presence of dopamine (DA), a neurotransmitter associated with diseases such as Alzheimer's and Parkinson's, with detection limits in the order of 10(-6) mol L(-1). The use of DS 01 in LbL film generated selectivity in the detection of DA despite the presence of ascorbic acid found in biological fluids. This work is the first to report that the antimicrobial peptide and NiTsPc LbL film exhibits electroanalytical activity to DA oxidation. The selectivity in the detection of DA is a fundamental aspect for the development of electrochemical sensors with potential applications in the biomedical and pharmaceutical industries.

  13. Development of a Novel Biosensor Using Cationic Antimicrobial Peptide and Nickel Phthalocyanine Ultrathin Films for Electrochemical Detection of Dopamine

    Directory of Open Access Journals (Sweden)

    Maysa F. Zampa

    2012-01-01

    Full Text Available The antimicrobial peptide dermaseptin 01 (DS 01, from the skin secretion of Phyllomedusa hypochondrialis frogs, was immobilized in nanostructured layered films in conjunction with nickel tetrasulfonated phthalocyanines (NiTsPc, widely used in electronic devices, using layer-by-layer technique. The films were used as a biosensor to detect the presence of dopamine (DA, a neurotransmitter associated with diseases such as Alzheimer's and Parkinson's, with detection limits in the order of 10−6 mol L−1. The use of DS 01 in LbL film generated selectivity in the detection of DA despite the presence of ascorbic acid found in biological fluids. This work is the first to report that the antimicrobial peptide and NiTsPc LbL film exhibits electroanalytical activity to DA oxidation. The selectivity in the detection of DA is a fundamental aspect for the development of electrochemical sensors with potential applications in the biomedical and pharmaceutical industries.

  14. A Sensitive and Selective Label-Free Electrochemical DNA Biosensor for the Detection of Specific Dengue Virus Serotype 3 Sequences

    Directory of Open Access Journals (Sweden)

    Natália Oliveira

    2015-07-01

    Full Text Available Dengue fever is the most prevalent vector-borne disease in the world, with nearly 100 million people infected every year. Early diagnosis and identification of the pathogen are crucial steps for the treatment and for prevention of the disease, mainly in areas where the co-circulation of different serotypes is common, increasing the outcome of dengue hemorrhagic fever (DHF and dengue shock syndrome (DSS. Due to the lack of fast and inexpensive methods available for the identification of dengue serotypes, herein we report the development of an electrochemical DNA biosensor for the detection of sequences of dengue virus serotype 3 (DENV-3. DENV-3 probe was designed using bioinformatics software and differential pulse voltammetry (DPV was used for electrochemical analysis. The results showed that a 22-m sequence was the best DNA probe for the identification of DENV-3. The optimum concentration of the DNA probe immobilized onto the electrode surface is 500 nM and a low detection limit of the system (3.09 nM. Moreover, this system allows selective detection of DENV-3 sequences in buffer and human serum solutions. Therefore, the application of DNA biosensors for diagnostics at the molecular level may contribute to future advances in the implementation of specific, effective and rapid detection methods for the diagnosis dengue viruses.

  15. A Sensitive and Selective Label-Free Electrochemical DNA Biosensor for the Detection of Specific Dengue Virus Serotype 3 Sequences.

    Science.gov (United States)

    Oliveira, Natália; Souza, Elaine; Ferreira, Danielly; Zanforlin, Deborah; Bezerra, Wessulla; Borba, Maria Amélia; Arruda, Mariana; Lopes, Kennya; Nascimento, Gustavo; Martins, Danyelly; Cordeiro, Marli; Lima-Filho, José

    2015-07-01

    Dengue fever is the most prevalent vector-borne disease in the world, with nearly 100 million people infected every year. Early diagnosis and identification of the pathogen are crucial steps for the treatment and for prevention of the disease, mainly in areas where the co-circulation of different serotypes is common, increasing the outcome of dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Due to the lack of fast and inexpensive methods available for the identification of dengue serotypes, herein we report the development of an electrochemical DNA biosensor for the detection of sequences of dengue virus serotype 3 (DENV-3). DENV-3 probe was designed using bioinformatics software and differential pulse voltammetry (DPV) was used for electrochemical analysis. The results showed that a 22-m sequence was the best DNA probe for the identification of DENV-3. The optimum concentration of the DNA probe immobilized onto the electrode surface is 500 nM and a low detection limit of the system (3.09 nM). Moreover, this system allows selective detection of DENV-3 sequences in buffer and human serum solutions. Therefore, the application of DNA biosensors for diagnostics at the molecular level may contribute to future advances in the implementation of specific, effective and rapid detection methods for the diagnosis dengue viruses.

  16. An electrochemical DNA biosensor based on nitrogen-doped graphene/Au nanoparticles for human multidrug resistance gene detection.

    Science.gov (United States)

    Chen, Mei; Hou, Changjun; Huo, Danqun; Bao, Jing; Fa, Huanbao; Shen, Caihong

    2016-11-15

    Multidrug resistance (MDR) has become a major obstacle to the adequate treatment of cancer patients; thus, there is an urgent need for exploring new strategies for early diagnosis of MDR in clinic. Here, we report a novel electrochemical biosensor based on nitrogen-doped graphene nanosheets functionalized with Au nanoparticles (N-G/Au) for sensitive and selective DNA detection. The highly conductive nanocomposite layer was characterized by using scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and cyclic voltammetry. DNA with thiol groups at the 5' end was immobilized on the N-G/Au surface via the strong Au-S bond. Differential pulse voltammetry was applied to monitor the target DNA hybridization event using methylene blue as an electrochemical indicator. Under optimal conditions, the biosensor could detect target DNA down to 3.12×10(-15)M with a linear range from 1.0×10(-14) to 1.0×10(-7)M, showing high sensitivity. Further, the sensing strategy was successfully used for detecting MDR1 DNA in real clinical samples. These results will aid in developing a new portable detection system for MDR that will allow effective diagnosis in the early stages of related cancer. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. A novel electrochemical aptasensor based on arch-shape structure of aptamer-complimentary strand conjugate and exonuclease I for sensitive detection of streptomycin.

    Science.gov (United States)

    Mohammad Danesh, Noor; Ramezani, Mohammad; Sarreshtehdar Emrani, Ahmad; Abnous, Khalil; Taghdisi, Seyed Mohammad

    2016-01-15

    Detection and quantitation of antibiotic residues in blood serum and animal foodstuffs are of great significance. In this study, an electrochemical aptasensor was developed for sensitive and selective detection of streptomycin, based on exonuclease I (Exo I), complimentary strand of aptamer (CS), Arch-shape structure of aptamer (Apt)-CS conjugate and gold electrode. The designed aptasensor inherits characteristics of gold including large surface area and high electrochemical conductivity, as well as high sensitivity and selectivity of aptamer toward its target, property of Arch-shape structure of Apt-CS conjugate to act as a gate and barrier for the access of redox probe to the surface of electrode and the function of Exo I as an enzyme which selectively digests the 3'-end of single stranded DNA (ssDNA). In the absence of streptomycin the gate remains closed. Thus, the electrochemical signal is weak. Upon addition of streptomycin, the Apt leaves the CS and binds to streptomycin and the Arch-shape structure is disassembled. Then, Exo I addition leads to a strong electrochemical signal. The designed electrochemical aptasensor exhibited high selectivity toward streptomycin with a limit of detection (LOD) as low as 11.4nM. Moreover, the developed electrochemical aptasensor was successfully used to detect streptomycin in milk and serum with LODs of 14.1 and 15.3nM, respectively.

  18. Electrochemical oxidation and cleavage of peptides analyzed with on-line mass spectrometric detection

    NARCIS (Netherlands)

    Permentier, H.P.; Jurva, U; Barroso, B.; Bruins, A.P.

    2003-01-01

    An on-line electrochernistry/electrospray mass spectrometry system (EC/MS) is described that allows fast analysis of the oxidation products of peptides. A range of peptides was oxidized in an electrochemical cell by application of a potential ramp from 0 to 1.5 V during passage of the sample. Electr

  19. Sensitive Electrochemical Detection of Native and Aggregated -Synuclein Protein Involved in Parkinson's Disease

    NARCIS (Netherlands)

    Masarik, Michal; Stobiecka, Agata; Kizek, René; Jelen, Frantisek; Pechan, Zdenk; Hoyer, Wolfgang; Subramaniam, Vinod; Palecek, Emil

    2004-01-01

    The aggregation of α-synuclein, a 14 kDa protein, is involved in several human neurodegenerative disorders, including Parkinson's disease. We studied native and in vitro aggregated α-synuclein by circular dichroism (CD), atomic force microscopy (AFM) and electrochemical methods. We used constant cur

  20. Localization of proteins in paint cross-sections by scanning electrochemical microscopy as an alternative immunochemical detection technique

    Energy Technology Data Exchange (ETDEWEB)

    Sciutto, Giorgia; Prati, Silvia [Microchemistry and Microscopy Art Diagnostic Laboratory, University of Bologna, Via Guaccimanni 42, Ravenna 48121 (Italy); Department of Chemistry “G. Ciamician”, University of Bologna, Via Selmi, Bologna 2 40126 (Italy); Mazzeo, Rocco, E-mail: rocco.mazzeo@unibo.it [Microchemistry and Microscopy Art Diagnostic Laboratory, University of Bologna, Via Guaccimanni 42, Ravenna 48121 (Italy); Department of Chemistry “G. Ciamician”, University of Bologna, Via Selmi, Bologna 2 40126 (Italy); Zangheri, Martina; Roda, Aldo; Bardini, Luca; Valenti, Giovanni; Rapino, Stefania [Department of Chemistry “G. Ciamician”, University of Bologna, Via Selmi, Bologna 2 40126 (Italy); Marcaccio, Massimo, E-mail: massimo.marcaccio@unibo.it [Department of Chemistry “G. Ciamician”, University of Bologna, Via Selmi, Bologna 2 40126 (Italy)

    2014-06-01

    Highlights: • Advanced immuno-electrochemical detection of proteins in paint samples by SECM. • Analysis performed directly on cross-section with high spatial resolution. • Identification of HRP catalytic activity for a selective location of analyte. • Satisfactory results were obtained for aged real samples. • The way forward for an extensive application of SECM in conservation science is shown. - Abstract: The qualitative identification of proteinaceous substances, as well as their location within a complex paint stratigraphy, is one of the most challenging issues in the characterization of painting materials. Nevertheless, information on paint components represent a crucial task for studies concerning both the ancient painting techniques adopted and the state of conservation, being fundamental investigations for the selection of appropriate conservation actions. The present research was aimed at developing a new detection approach for the immunochemical localization of ovalbumin in paint cross-sections based on the use of scanning electrochemical microscopy (SECM). The immunochemical analyses were performed using an anti-ovalbumin primary antibody and a secondary antibody labelled with horseradish peroxidase (HRP). SECM measurements were performed in feedback mode using benzoquinone (BQ)/hydroquinone (H{sub 2}Q) redox couple. In presence of hydrogen peroxide (H{sub 2}O{sub 2}), HRP catalyzes the re-oxidation of H{sub 2}Q to BQ and the increment of BQ concentration in correspondence of the target protein was detected by SECM through the electrochemical reduction of the regenerated BQ at the microelectrode. Indeed, the localization of ovalbumin was possible thanks to a clear discrimination of SECM currents, achieved by the comparison of the measurements recorded before and after H{sub 2}O{sub 2} administration, based on the HRP on/off approach. The method was evaluated both on samples from standard mocks-up and on a historical sample, collected from a

  1. Electrochemical hydride generation atomic fluorescence spectrometry for detection of tin in canned foods using polyaniline-modified lead cathode.

    Science.gov (United States)

    Jiang, Xianjuan; Gan, Wuer; Wan, Lingzhong; Deng, Yun; Yang, Qinghua; He, Youzhao

    2010-12-15

    An electrochemical hydride generation system with polyaniline-modified lead cathode was developed for tin determination by coupling with atomic fluorescence spectrometry. The tin fluorescence signal intensity was improved evidently as the polyaniline membrane could facilitate the transformation process from atomic tin to the SnH(4) and prevent the aggradation of Sn atom on Pb electrode surface. The effects of experimental parameters and interferences have been studied. The limit of detection (LOD) was 1.5 ng mL(-1) (3σ) and the relative standard deviation (RSD) was 3.3% for 11 consecutive measurements of 50 ng mL(-1) Sn(IV) standard solution.

  2. Determination of methyldibromoglutaronitrile in cosmetic products by high-performance liquid chromatography with electrochemical detection. Method validation

    DEFF Research Database (Denmark)

    Rastogi, Suresh Chandra; Zachariae, Claus; Johansen, Jeanne D

    2004-01-01

    An increased frequency of contact allergy to methyldibromoglutaronitrile (MDBGN), a commonly used preservative in cosmetics and other consumer products, has been reported in recent years. A high-performance liquid chromatography (HPLC) method for the determination of MDBGN in cosmetic products has...... been validated in the present study. The identification is performed by reductive electrochemical detection of the bromine present in the molecule. The method is suitable for compliance testing of cosmetic products as well as for the research to support clinical and epidemiological studies....

  3. Uniform chromatographic conditions for quantifying urinary catecholamines, metanephrines, vanillylmandelic acid, 5-hydroxyindoleacetic acid, by liquid chromatography, with electrochemical detection.

    Science.gov (United States)

    Parker, N C; Levtzow, C B; Wright, P W; Woodard, L L; Chapman, J F

    1986-08-01

    Uniform liquid-chromatographic conditions were developed such that we could quantify norepinephrine, epinephrine, normetanephrine, metanephrine, vanillylmandelic acid, and 5-hydroxyindoleacetic acid in urine by using a single mobile phase of monochloroacetic acid and citric acid, 0.1 mol/L each. All compounds were separated on a C18 column and detected electrochemically at a potential of +0.800 V. Optimization of these uniform chromatographic conditions significantly shortens the changeover time required from one assay to another, resulting in a substantial savings of time and cost to the laboratory.

  4. The Polypyrrole/Multiwalled Carbon Nanotube Modified Au Microelectrode for Sensitive Electrochemical Detection of Trace Levels of Pb2+

    Directory of Open Access Journals (Sweden)

    Xuxing Zhu

    2017-03-01

    Full Text Available The sensitive detection of trace levels of heavy metal ions such as Pb2+ is of significant importance due to the health hazard they pose. In this paper, we present a polypyrrole (PPy/multiwalled carbon nanotube (MWCNT-modified Au microelectrode. The PPy/MWCNT composite film was electrochemically deposited on the microelectrode by cyclic voltammetry (CV. The composite film was investigated by scanning electron microscope (SEM, CV, and electrochemical impedance spectroscopy (EIS, and the results show that this film presents a uniformly distributed and web-like entangled structure and good conductivity. Differential pulse stripping voltammetry (DPSV was applied to determine trace levels of Pb2+. Experimental conditions including accumulation time and deposition potential were optimized. In optimal conditions, the PPy/MWCNT-modified microelectrode performed sensitive detection of Pb2+ within a concentration range from 1 to 100 μg·L−1, and the limit of detection was 0.65 μg·L−1 at the signal-to-noise ratio of three.

  5. Electrochemical detection of Bisphenol A with high sensitivity and selectivity using recombinant protein-immobilized graphene electrodes.

    Science.gov (United States)

    Kim, Kwang Su; Jang, Ji-ryang; Choe, Woo-Seok; Yoo, Pil J

    2015-09-15

    A novel Bisphenol A (4,4'-isopropylidenediphenol, BPA) sensor was developed harnessing an electrochemical platform comprising a layer-by-layer assembled reduced graphene oxide (rGO) electrode and a designer probe specifically recognizing BPA. The BPA detection probe, a recombinant protein (LacI-BPA), was constructed by fusing a disulfide-constrained high affinity BPA binding peptide (CKSLENSYC) to the C-terminus of Lac repressor (LacI). Following expression and purification, the LacI-BPA was heat-denatured on-purpose to facilitate its direct adhesion on the rGO electrode surface via pi-stacking interaction. When the performance of the fabricated BPA sensor (LacI-BPA/rGO) was assessed by electrochemical impedance spectroscopy (EIS), it showed a wide linear dynamic range of BPA detection spanning from 100 fM to 10nM. Moreover, our BPA sensor exhibited negligible cross reactivity to BPA analogs such as Bisphenol S (BPS) and Bisphenol F (BPF) and almost complete spike recovery of BPA from plastic extracts containing various potential interferents. With these merits, the BPA sensor developed in the present study is expected to find practical application in selective and sensitive detection of BPA from diverse sample solutions.

  6. Electrospun polyamide 6/poly(allylamine hydrochloride) nanofibers functionalized with carbon nanotubes for electrochemical detection of dopamine.

    Science.gov (United States)

    Mercante, Luiza A; Pavinatto, Adriana; Iwaki, Leonardo E O; Scagion, Vanessa P; Zucolotto, Valtencir; Oliveira, Osvaldo N; Mattoso, Luiz H C; Correa, Daniel S

    2015-03-04

    The use of nanomaterials as an electroactive medium has improved the performance of bio/chemical sensors, particularly when synergy is reached upon combining distinct materials. In this paper, we report on a novel architecture comprising electrospun polyamide 6/poly(allylamine hydrochloride) (PA6/PAH) nanofibers functionalized with multiwalled carbon nanotubes, used to detect the neurotransmitter dopamine (DA). Miscibility of PA6 and PAH was sufficient to form a single phase material, as indicated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), leading to nanofibers with no beads onto which the nanotubes could adsorb strongly. Differential pulse voltammetry was employed with indium tin oxide (ITO) electrodes coated with the functionalized nanofibers for the selective electrochemical detection of dopamine (DA), with no interference from uric acid (UA) and ascorbic acid (AA) that are normally present in biological fluids. The response was linear for a DA concentration range from 1 to 70 μmol L(-1), with detection limit of 0.15 μmol L(-1) (S/N = 3). The concepts behind the novel architecture to modify electrodes can be potentially harnessed in other electrochemical sensors and biosensors.

  7. A novel label-free electrochemical immunosensor based on functionalized nitrogen-doped graphene quantum dots for carcinoembryonic antigen detection.

    Science.gov (United States)

    Yang, Yuying; Liu, Qing; Liu, Yan; Cui, Jianjian; Liu, Hui; Wang, Ping; Li, Yueyun; Chen, Lei; Zhao, Zengdian; Dong, Yunhui

    2017-04-15

    A novel and ultrasensitive label-free electrochemical immunosensor was fabricated for quantitative detection of carcino-embryonic antigen (CEA). The nitrogen-doped graphene quantum dots (N-GQDs) supported PtPd bimetallic nanoparticles (PtPd/N-GQDs) were synthesized by a simple and green hydrothermal procedure. Subsequently, PtPd/N-GQDs functionalized Au nanoparticles (PtPd/N-GQDs@Au) were prepared successfully via a self-assembly approach. Because of the synergetic effect present in PtPd/N-GQDs@Au, this novel nanocomposites has shown excellent electrocatalytic activity towards hydrogen peroxide (H2O2) reduction. Featuring good biocompatibility, excellent conductivity and large surface area, PtPd/N-GQDs@Au was applied as transducing materials to efficiently conjugate capture antibodies and amplify electrochemical signal. Under the optimal conditions, the proposed immunosensor was used for the detection of CEA with wide dynamic range in the range from 5 fg/mL to 50ng/mL with a low detection limit of 2fg/mL (S/N=3). Furthermore, this label-free immunosensor possesses high sensitivity, special selectivity and long-term stability, which shows promising application in bioassay analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Electrochemical Sensors Based on Screen-Printed Electrodes: The Use of Phthalocyanine Derivatives for Application in VFA Detection

    Science.gov (United States)

    Ndiaye, Amadou L.; Delile, Sébastien; Brunet, Jérôme; Varenne, Christelle; Pauly, Alain

    2016-01-01

    Here, we report on the use of electrochemical methods for the detection of volatiles fatty acids (VFAs), namely acetic acid. We used tetra-tert-butyl phthalocyanine (PcH2-tBu) as the sensing material and investigated its electroanalytical properties by means of cyclic voltammetry (CV) and square wave voltammetry (SWV). To realize the electrochemical sensing system, the PcH2-tBu has been dropcast-deposited on carbon (C) orgold (Au)screen-printed electrodes (SPEs) and characterized by cyclic voltammetry and scanning electron microscopy (SEM). The SEM analysis reveals that the PcH2-tBu forms mainly aggregates on the SPEs. The modified electrodes are used for the detection of acetic acid and present a linear current increase when the acetic acid concentration increases. The Cmodified electrode presents a limit of detection (LOD) of 25.77 mM in the range of 100 mM–400 mM, while the Aumodified electrode presents an LOD averaging 40.89 mM in the range of 50 mM–300 mM. When the experiment is realized in a buffered condition, theCmodified electrode presents a lower LOD, which averagesthe 7.76 mM. A pronounced signal decay attributed to an electrode alteration is observed in the case of the gold electrode. This electrode alteration severely affects the coating stability. This alteration is less perceptible in the case of the carbon electrode. PMID:27598214

  9. Electrochemical Sensors Based on Screen-Printed Electrodes: The Use of Phthalocyanine Derivatives for Application in VFA Detection

    Directory of Open Access Journals (Sweden)

    Amadou L. Ndiaye

    2016-09-01

    Full Text Available Here, we report on the use of electrochemical methods for the detection of volatiles fatty acids (VFAs, namely acetic acid. We used tetra-tert-butyl phthalocyanine (PcH2-tBu as the sensing material and investigated its electroanalytical properties by means of cyclic voltammetry (CV and square wave voltammetry (SWV. To realize the electrochemical sensing system, the PcH2-tBu has been dropcast-deposited on carbon (C orgold (Auscreen-printed electrodes (SPEs and characterized by cyclic voltammetry and scanning electron microscopy (SEM. The SEM analysis reveals that the PcH2-tBu forms mainly aggregates on the SPEs. The modified electrodes are used for the detection of acetic acid and present a linear current increase when the acetic acid concentration increases. The Cmodified electrode presents a limit of detection (LOD of 25.77 mM in the range of 100 mM–400 mM, while the Aumodified electrode presents an LOD averaging 40.89 mM in the range of 50 mM–300 mM. When the experiment is realized in a buffered condition, theCmodified electrode presents a lower LOD, which averagesthe 7.76 mM. A pronounced signal decay attributed to an electrode alteration is observed in the case of the gold electrode. This electrode alteration severely affects the coating stability. This alteration is less perceptible in the case of the carbon electrode.

  10. Label-free electrochemical immunosensor based on gold-silicon carbide nanocomposites for sensitive detection of human chorionic gonadotrophin.

    Science.gov (United States)

    Yang, Long; Zhao, Hui; Fan, Shuangmei; Deng, Shuangsheng; Lv, Qi; Lin, Jie; Li, Can-Peng

    2014-07-15

    Uniform and highly dispersed gold-silicon carbide (Au@SiC) nanocomposites were prepared via simple way and used for fabrication of label-free electrochemical immunosensor for sensitive detection of human chorionic gonadotrophin (hCG). Using Au@SiC as electrode material and using ferricyanide as mediator, the proposed immunosensor provides a simple and economic method with higher sensitivity and a wider concentration range for detection of hCG. Under the optimal condition, the approach provided a good linear response range from 0.1 to 5 IU/L and 5 to 1000 IU/L with a low detection limit of 0.042 IU/L. The immunosensor showed good selectivity, acceptable stability and reproducibility. Satisfactory results were obtained for determination of hCG in human serum samples. The proposed method provides a promising platform of clinical immunoassay for other biomolecules. In addition, the bio-functionalization of SiC combined with other nanomaterials will provide promising approach for electrochemical sensing and biosensing platform.

  11. Signal-on electrochemical detection of antibiotics at zeptomole level based on target-aptamer binding triggered multiple recycling amplification.

    Science.gov (United States)

    Wang, Hongzhi; Wang, Yu; Liu, Su; Yu, Jinghua; Guo, Yuna; Xu, Ying; Huang, Jiadong

    2016-06-15

    In the work, a signal-on electrochemical DNA sensor based on multiple amplification for ultrasensitive detection of antibiotics has been reported. In the presence of target, the ingeniously designed hairpin probe (HP1) is opened and the polymerase-assisted target recycling amplification is triggered, resulting in autonomous generation of secondary target. It is worth noting that the produced secondary target could not only hybridize with other HP1, but also displace the Helper from the electrode. Consequently, methylene blue labeled HP2 forms a "close" probe structure, and the increase of signal is monitored. The increasing current provides an ultrasensitive electrochemical detection for antibiotics down to 1.3 fM. To our best knowledge, such work is the first report about multiple recycling amplification combing with signal-on sensing strategy, which has been utilized for quantitative determination of antibiotics. It would be further used as a general strategy associated with more analytical techniques toward the detection of a wide spectrum of analytes. Thus, it holds great potential for the development of ultrasensitive biosensing platform for the applications in bioanalysis, disease diagnostics, and clinical biomedicine.

  12. Electrochemical detection of hydrogen peroxide on platinum-containing tetrahedral amorphous carbon sensors and evaluation of their biofouling properties.

    Science.gov (United States)

    Tujunen, Noora; Kaivosoja, Emilia; Protopopova, Vera; Valle-Delgado, Juan José; Österberg, Monika; Koskinen, Jari; Laurila, Tomi

    2015-10-01

    Hydrogen peroxide is the product of various enzymatic reactions, and is thus typically utilized as the analyte in biosensors. However, its detection with conventional materials, such as noble metals or glassy carbon, is often hindered by slow kinetics and biofouling of the electrode. In this study electrochemical properties and suitability to peroxide detection as well as ability to resist biofouling of Pt-doped ta-C samples were evaluated. Pure ta-C and pure Pt were used as references. According to the results presented here it is proposed that combining ta-C with Pt results in good electrocatalytic activity towards H2O2 oxidation with better tolerance towards aqueous environment mimicking physiological conditions compared to pure Pt. In biofouling experiments, however, both the hybrid material and Pt were almost completely blocked after immersion in protein-containing solutions and did not produce any peaks for ferrocenemethanol oxidation or reduction. On the contrary, it was still possible to obtain clear peaks for H2O2 oxidation with them after similar treatment. Moreover, quartz crystal microbalance experiment showed less protein adsorption on the hybrid sample compared to Pt which is also supported by the electrochemical biofouling experiments for H2O2 detection.

  13. Ultrasensitive electrochemical detection of secretoneurin based on Pb(2+)-decorated reduced graphene oxide-tetraethylene pentamine as a label.

    Science.gov (United States)

    Yuan, Guolin; Chen, Huali; Xia, Chunyong; Gao, Liuliu; Yu, Chao

    2015-07-15

    In this work, a novel electrochemical immunosensor for the detection of secretoneurin (SN), which uses metal ion functionalised reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) as a label, is reported for the first time. rGO-TEPA contains a large number of amino groups, which makes it an ideal templet for the loading of metal ions. rGO-TEPA-Pb(2+) was employed to immobilise secondary secretoneurin (SN) antibody (Ab2), and the resulting nanocomposite (Ab2-rGO-TEPA-Pb(2+)) was used as a trace tag for signal amplification. A modified electrode consisting of functionalised graphene nanosheets (Au@GS) was used as a substrate to immobilise the antibodies. Under the optimal conditions, the immunoassay exhibited high sensitivity, acceptable stability and reproducibility with a wide linear range from 0.001 to 100ngmL(-1) (R=0.996), and an ultra-low detection limit of 0.33pgmL(-1) (S/N=3). Furthermore, the immunosensor could be employed to detect SN in clinical serum samples. The proposed sensing strategy enriches the electrochemical immunoassay and exhibits potential for the point-of-care diagnostic application of the clinical screening of biomarkers.

  14. Magnetic Bead/Gold Nanoparticle Double-Labeled Primers for Electrochemical Detection of Isothermal Amplified Leishmania DNA.

    Science.gov (United States)

    de la Escosura-Muñiz, Alfredo; Baptista-Pires, Luis; Serrano, Lorena; Altet, Laura; Francino, Olga; Sánchez, Armand; Merkoçi, Arben

    2016-01-13

    A novel methodology for the isothermal amplification of Leishmania DNA using labeled primers combined with the advantages of magnetic purification/preconcentration and the use of gold nanoparticle (AuNP) tags for the sensitive electrochemical detection of such amplified DNA is developed. Primers labeled with AuNPs and magnetic beads (MBs) are used for the first time for the isothermal amplification reaction, being the amplified product ready for the electrochemical detection. The electrocatalytic activity of the AuNP tags toward the hydrogen evolution reaction allows the rapid quantification of the DNA on screen-printed carbon electrodes. Amplified products from the blood of dogs with Leishmania (positive samples) are discriminated from those of healthy dogs (blank samples). Quantitative studies demonstrate that the optimized method allows us to detect less than one parasite per microliter of blood (8 × 10(-3) parasites in the isothermal amplification reaction). This pioneering approach is much more sensitive than traditional methods based on real-time polymerase chain reaction (PCR), and is also more rapid, cheap, and user-friendly.

  15. Label-free electrochemical impedance biosensor to detect human interleukin-8 in serum with sub-pg/ml sensitivity.

    Science.gov (United States)

    Sharma, R; Deacon, S E; Nowak, D; George, S E; Szymonik, M P; Tang, A A S; Tomlinson, D C; Davies, A G; McPherson, M J; Wälti, C

    2016-06-15

    Biosensors with high sensitivity and short time-to-result that are capable of detecting biomarkers in body fluids such as serum are an important prerequisite for early diagnostics in modern healthcare provision. Here, we report the development of an electrochemical impedance-based sensor for the detection in serum of human interleukin-8 (IL-8), a pro-angiogenic chemokine implicated in a wide range of inflammatory diseases. The sensor employs a small and robust synthetic non-antibody capture protein based on a cystatin scaffold that displays high affinity for human IL-8 with a KD of 35 ± 10 nM and excellent ligand specificity. The change in the phase of the electrochemical impedance from the serum baseline, ∆θ(ƒ), measured at 0.1 Hz, was used as the measure for quantifying IL-8 concentration in the fluid. Optimal sensor signal was observed after 15 min incubation, and the sensor exhibited a linear response versus logarithm of IL-8 concentration from 900 fg/ml to 900 ng/ml. A detection limit of around 90 fg/ml, which is significantly lower than the basal clinical levels of 5-10 pg/ml, was observed. Our results are significant for the development of point-of-care and early diagnostics where high sensitivity and short time-to-results are essential.

  16. Comparison of Electrochemical Immunosensors and Aptasensors for Detection of Small Organic Molecules in Environment, Food Safety, Clinical and Public Security

    Directory of Open Access Journals (Sweden)

    Benoit Piro

    2016-02-01

    Full Text Available We review here the most frequently reported targets among the electrochemical immunosensors and aptasensors: antibiotics, bisphenol A, cocaine, ochratoxin A and estradiol. In each case, the immobilization procedures are described as well as the transduction schemes and the limits of detection. It is shown that limits of detections are generally two to three orders of magnitude lower for immunosensors than for aptasensors, due to the highest affinities of antibodies. No significant progresses have been made to improve these affinities, but transduction schemes were improved instead, which lead to a regular improvement of the limit of detections corresponding to ca. five orders of magnitude over these last 10 years. These progresses depend on the target, however.

  17. Comparison of Electrochemical Immunosensors and Aptasensors for Detection of Small Organic Molecules in Environment, Food Safety, Clinical and Public Security

    Science.gov (United States)

    Piro, Benoit; Shi, Shihui; Reisberg, Steeve; Noël, Vincent; Anquetin, Guillaume

    2016-01-01

    We review here the most frequently reported targets among the electrochemical immunosensors and aptasensors: antibiotics, bisphenol A, cocaine, ochratoxin A and estradiol. In each case, the immobilization procedures are described as well as the transduction schemes and the limits of detection. It is shown that limits of detections are generally two to three orders of magnitude lower for immunosensors than for aptasensors, due to the highest affinities of antibodies. No significant progresses have been made to improve these affinities, but transduction schemes were improved instead, which lead to a regular improvement of the limit of detections corresponding to ca. five orders of magnitude over these last 10 years. These progresses depend on the target, however. PMID:26938570

  18. Rapid separation of strychnine and brucine on a dynamically modified poly(dimethylsiloxane) microchip followed by electrochemical detection.

    Science.gov (United States)

    Zhang, Q L; Xu, J J; Lian, H Z; Li, X Y; Chen, H Y

    2006-01-01

    A method has been developed for rapidly separating and detecting strychnine and brucine using a poly(dimethysiloxane) (PDMS) microchip and electrochemical (EC) detection. PDMS microchannels dynamically modified by Brij35 are shown to be more efficient than native ones. The two analytes are well separated within 90 s in 70 mmol/L acetate buffer (pH 5.5) containing 0.01% (v/v) Brij35. Detection limits were found to be 1.0 micromol/L for strychnine and 0.2 micromol/L for brucine at S/N = 3. The method was used to determine trace strychnine and brucine in rat serum, and the results obtained correlate well with those obtained via high-performance liquid chromatography (HPLC).

  19. Highly sensitive assay for the measurement of serotonin in microdialysates using capillary high-performance liquid chromatography with electrochemical detection.

    Science.gov (United States)

    Parrot, Sandrine; Lambás-Señas, Laura; Sentenac, Sabine; Denoroy, Luc; Renaud, Bernard

    2007-05-01

    A highly sensitive isocratic capillary high-performance liquid chromatographic (HPLC) method with electrochemical detection (ED) for the simultaneous measurement of serotonin (5-hydroxytryptamine, 5-HT) and its metabolite 5-hydroxyindole-3-acetic acid (5-HIAA) in microdialysates has been developed using a 0.5 mm i.d. capillary column and a 11-nL detection cell. This method, validated on both pharmacological and analytical bases, can be performed using injection volumes as low as 1 microL. The limits of detection were 5.6 x 10(-11)mol/L and 3.0 x 10(-9)mol/L for 5-HT and 5-HIAA. Several applications of the present method are given on microdialysates from rodent brain and human spinal cord.

  20. A Nonenzymatic Electrochemical Immunosensor for Ultrasensitive Detection of Tumor Biomarkers Based on Palladium Nanoparticles Conjugated Reduced Graphene Nanosheets.

    Science.gov (United States)

    Li, WenTing; Li, YiSong; Wu, YongKang; Liao, JinFeng; Qi, TingTing; Li, He; Li, Jun; Zhang, XiaoNing; Qian, ZhiYong

    2015-11-01

    A nonenzymatic electrochemical immunosensor based on palladium nanoparticles conjugated reduced graphene nanosheets (Pd-GS) for sensitive detection of cancer biomarker a-fetoprotein (AFP) is described. Primary antibody-AFP (Ab1) was immobilized onto the surface of reduced graphene nanosheets (rGO) through an amidation reaction between the carboxylic acid group of the rGO and the available amine groups of Ab1. Pd-GS which was prepared by one-spot synthesis is employed to immobilize secondary antibody (Ab2). The resulting Pd-GS-Ab2 conjugate was used as a label for the immunosensor to detect AFP. The amplified immunoassay exhibits high sensitivity, wide linear rang (0.01-10 ng/mL), low detection limit (3.0 pg/mL), acceptable stability and reproducibility. And such immunosensor also shows good recovery in the assay results for AFP in human serum samples.

  1. Detection of magnetising inrush current using real time integration method

    Science.gov (United States)

    Ling, P. C. Y.; Basak, A.

    1990-01-01

    A technique of predicting magnetising inrush currents in transformers is described. Computed results show an inconsistency in second harmonic decay resulting detection failure while using conventional second harmonic techniques. A new detection scheme using real time integration values of the inrush current is proposed to provide reliable relay operation.

  2. A kinetic study of ferrocenium cation decomposition utilizing an integrated electrochemical methodology composed of cyclic voltammetry and amperometry.

    Science.gov (United States)

    Singh, Archana; Chowdhury, Debarati Roy; Paul, Amit

    2014-11-21

    A novel, easy, quick, and inexpensive integrated electrochemical methodology composed of cyclic voltammetry and amperometry has been developed for the determination of the kinetic stability of higher oxidation states for inorganic complexes. In this study, ferrocene and its derivatives have been used as model systems and the corresponding ferrocenium cations were generated in situ during the electrochemical experiments to determine their kinetic stabilities. The study found that the ferrocenium cations decompose following the first-order kinetics at 27 ± 3 °C in the presence of ambient oxygen and water. The half-lives of the ferrocenium, carboxylate ferrocenium, and decamethyl ferrocenium cations were found to be 1.27 × 10(3), 1.52 × 10(3), and ≫11.0 × 10(3) s, respectively, in acetonitrile solvent having a 0.5 M tetrabutylammonium hexafluorophosphate electrolyte. These results are in agreement with the previous reports, i.e. the ferrocenium cation is unstable whereas the decamethyl ferrocenium cation has superior stability. The new methodology has been established by performing various experiments using different concentrations of ferrocene, variable scan rates in cyclic voltammetry, different time periods for amperometry, and in situ spectroelectrochemical experiments.

  3. Integrated circuit authentication hardware Trojans and counterfeit detection

    CERN Document Server

    Tehranipoor, Mohammad; Zhang, Xuehui

    2013-01-01

    This book describes techniques to verify the authenticity of integrated circuits (ICs). It focuses on hardware Trojan detection and prevention and counterfeit detection and prevention. The authors discuss a variety of detection schemes and design methodologies for improving Trojan detection techniques, as well as various attempts at developing hardware Trojans in IP cores and ICs. While describing existing Trojan detection methods, the authors also analyze their effectiveness in disclosing various types of Trojans, and demonstrate several architecture-level solutions. 

  4. Multistage audiovisual integration of speech: dissociating identification and detection

    DEFF Research Database (Denmark)

    Eskelund, Kasper; Tuomainen, Jyrki; Andersen, Tobias

    2011-01-01

    Speech perception integrates auditory and visual information. This is evidenced by the McGurk illusion where seeing the talking face influences the auditory phonetic percept and by the audiovisual detection advantage where seeing the talking face influences the detectability of the acoustic speech...... signal. Here we show that identification of phonetic content and detection can be dissociated as speech-specific and non-specific audiovisual integration effects. To this end, we employed synthetically modified stimuli, sine wave speech (SWS), which is an impoverished speech signal that only observers...

  5. Decoding Network Structure in On-Chip Integrated Flow Cells with Synchronization of Electrochemical Oscillators

    Science.gov (United States)

    Jia, Yanxin; Kiss, István Z.

    2017-04-01

    The analysis of network interactions among dynamical units and the impact of the coupling on self-organized structures is a challenging task with implications in many biological and engineered systems. We explore the coupling topology that arises through the potential drops in a flow channel in a lab-on-chip device that accommodates chemical reactions on electrode arrays. The networks are revealed by analysis of the synchronization patterns with the use of an oscillatory chemical reaction (nickel electrodissolution) and are further confirmed by direct decoding using phase model analysis. In dual electrode configuration, a variety coupling schemes, (uni- or bidirectional positive or negative) were identified depending on the relative placement of the reference and counter electrodes (e.g., placed at the same or the opposite ends of the flow channel). With three electrodes, the network consists of a superposition of a localized (upstream) and global (all-to-all) coupling. With six electrodes, the unique, position dependent coupling topology resulted spatially organized partial synchronization such that there was a synchrony gradient along the quasi-one-dimensional spatial coordinate. The networked, electrode potential (current) spike generating electrochemical reactions hold potential for construction of an in-situ information processing unit to be used in electrochemical devices in sensors and batteries.

  6. Decoding Network Structure in On-Chip Integrated Flow Cells with Synchronization of Electrochemical Oscillators

    Science.gov (United States)

    Jia, Yanxin; Kiss, István Z.

    2017-01-01

    The analysis of network interactions among dynamical units and the impact of the coupling on self-organized structures is a challenging task with implications in many biological and engineered systems. We explore the coupling topology that arises through the potential drops in a flow channel in a lab-on-chip device that accommodates chemical reactions on electrode arrays. The networks are revealed by analysis of the synchronization patterns with the use of an oscillatory chemical reaction (nickel electrodissolution) and are further confirmed by direct decoding using phase model analysis. In dual electrode configuration, a variety coupling schemes, (uni- or bidirectional positive or negative) were identified depending on the relative placement of the reference and counter electrodes (e.g., placed at the same or the opposite ends of the flow channel). With three electrodes, the network consists of a superposition of a localized (upstream) and global (all-to-all) coupling. With six electrodes, the unique, position dependent coupling topology resulted spatially organized partial synchronization such that there was a synchrony gradient along the quasi-one-dimensional spatial coordinate. The networked, electrode potential (current) spike generating electrochemical reactions hold potential for construction of an in-situ information processing unit to be used in electrochemical devices in sensors and batteries. PMID:28387237

  7. Magnetic controllable biorecognition process of doxorubicin detected by electrochemical contact angle measurement.

    Science.gov (United States)

    Zhou, Jian; Zhang, Renyun; Li, Xiaomao; Gutmann, Sebastian; Lv, Gang; Wang, Xuemei

    2007-08-01

    Fe3O4 nanoparticles are the most commonly used magnetic materials with promising applications in biomedical and biochemical engineering. In this study, a novel application of the tetraheptylammonium capped Fe3O4 nanoparticles in controllable biorecognition process of anticancer drug doxorubicin through combination with external static magnetic field has been demonstrated. Our AFM and electrochemical studies illustrate that the presence of the tetraheptylammonium capped Fe3O4 nanoparticles could promote the binding behavior of doxorubicin to DNA. And the results of the electrochemical contact angle measurements indicate that the controllable biomolecular recognition of doxorubicin could be readily achieved by combining these functionalized Fe3O4 nanoparticles with changing the positions of external magnetic field.

  8. Determination of methyldibromoglutaronitrile in cosmetic products by high performance liquid chromatography with electrochemical detection.

    Science.gov (United States)

    Rooselaar, J; Weyland, J W

    1993-02-01

    Synopsis A method for the determination of methyldibromoglutaronitrile in cosmetic products is described. Reversed phase high performance liquid chromatography and reductive electrochemical detection is employed to provide for improved selectivity and detectability compared to alternative methods. The method detects 0.002% methyldibromoglutaronitrile in cosmetic products and has a linear range from 0.006 up to 0.06%, which can easily be extended to the legally allowed limit of 0.1% by means of a simple dilution step. At a level of 0.03% the coefficient of variation was estimated to be 1.7%. Recoveries measured were between 98 and 100%. The method has been subjected to a ruggedness test, which indicated that it was stable, but slightly sensitive for a decrease in the detection potential. More than 130 cosmetic products have been analysed using the method. In 19 samples methyldibromoglutaronitrile was detected in concentrations varying between 0.002% and 0.030%. Résumé Une méthode a été mise au point pour la détermination du methyldibromoglutaronitrile, un conservateur cosmétique dont l'utilisation est croissante. La méthode utilise la chromatographie liquide à haute performance avec détection électrochimique pour permettre une amélioration de la détection et de la spécificité. Selon une procédure simple, le methyldibromoglutaronitrile est séparé sur une colonne 100 RP8 (lichosphere MERCK) avec une phase mobile constituee d'eau et d'acétone (60/40 v/v) avec un ajout de sulfate de sodium et du chlorure de sodium pour obtenir des concentrations de 0.02 M et 0.002 M respectivement. Une électrode en or a été utilisée pour la détection avec un potentiel de fonctionnement de -0.6 V réductif. Une détection par pulsation a été nécessaire pour obtenir une réponse stable. Le détecteur a été programmé pourgarder l'électrode pour 10 ms à 1 V, 10 ms à-1 V (réductif) et à-0.6 V pour 100 ms, ce potentiel a été utilisé comme mesure. Des

  9. Multistage audiovisual integration of speech: dissociating identification and detection

    DEFF Research Database (Denmark)

    Eskelund, Kasper; Tuomainen, Jyrki; Andersen, Tobias

    2011-01-01

    Speech perception integrates auditory and visual information. This is evidenced by the McGurk illusion where seeing the talking face influences the auditory phonetic percept and by the audiovisual detection advantage where seeing the talking face influences the detectability of the acoustic speech...... signal. Here we show that identification of phonetic content and detection can be dissociated as speech-specific and non-specific audiovisual integration effects. To this end, we employed synthetically modified stimuli, sine wave speech (SWS), which is an impoverished speech signal that only observers...... informed of its speech-like nature recognize as speech. While the McGurk illusion only occurred for informed observers the audiovisual detection advantage occurred for naïve observers as well. This finding supports a multi-stage account of audiovisual integration of speech in which the many attributes...

  10. Evaluation of the BYG Carba Test, a New Electrochemical Assay for Rapid Laboratory Detection of Carbapenemase-Producing Enterobacteriaceae

    Science.gov (United States)

    Yunus, Sami; Massart, Marion; Huang, Te-Din; Glupczynski, Youri

    2015-01-01

    Accurate detection of carbapenemase-producing Enterobacteriaceae (CPE) constitutes a major laboratory diagnostic challenge. We evaluated an electrochemical technique (the BYG Carba test) which allows detection of CPE in less than 35 min. The BYG Carba test was first validated in triplicate against 57 collection isolates with previously characterized β-lactam resistance mechanisms (OXA-48, n = 12; KPC, n = 8; NDM, n = 8; VIM, n = 8; IMP, n = 3; GIM, n = 1; GES-6, n = 1; no carbapenemase, n = 16) and against a panel of 10 isolates obtained from the United Kingdom National External Quality Assessment Service (NEQAS). The test was then evaluated prospectively against 324 isolates referred to the national reference center for suspicion of CPE. The BYG Carba test results were compared with those obtained with the Carba NP test using multiplex PCR sequencing as the gold standard. Of the 57 collection and the 10 NEQAS isolates, all but one GES-6-producing isolate were correctly identified by the Carba BYG test. Among the 324 consecutive Enterobacteriaceae isolates tested prospectively, 146 were confirmed as noncarbapenemase producers by PCR while 178 harbored a carbapenemase gene (OXA-48, n = 117; KPC, n = 25; NDM, n = 23; and VIM, n = 13). Prospectively, in comparison with PCR results, the BYG Carba test displayed 95% sensitivity and 100% specificity versus 89% and 100%, respectively, for the Carba NP test. The BYG Carba test is a novel, rapid, and efficient assay based on an electro-active polymer biosensing technology discriminating between CPE and non-CPE. The precise electrochemical signal (electrochemical impedance variations) allows the establishment of real-time objective measurement and interpretation criteria which should facilitate the accreditation process of this technology. PMID:26637378

  11. Simultaneous electrochemical detection of ascorbic acid, dopamine and uric acid based on graphene anchored with Pd-Pt nanoparticles.

    Science.gov (United States)

    Yan, Jun; Liu, Shi; Zhang, Zhenqin; He, Guangwu; Zhou, Ping; Liang, Haiying; Tian, Lulu; Zhou, Xuemin; Jiang, Huijun

    2013-11-01

    Pd-Pt bimetallic nanoparticles anchored on functionalized reduced graphene oxide (RGO) nanomaterials were synthesized via a one-step in situ reduction process, in which Pt and Pd ions were first attached to poly(diallyldimethylammonium chloride) (PDDA) functionalized graphene oxide (GO) sheets, and then the encased metal ions and GO were subjected to simultaneous reduction by ethylene glycol. The as-prepared Pd3Pt1/PDDA-RGO nanocomposites were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and electrochemical methods. In addition, an electrochemical sensor based on the graphene nanocomposites was fabricated for the simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA) in their ternary mixture. Three well-separated voltammetric peaks along with remarkable increasing electro-oxidation currents were obtained in differential pulse voltammetry (DPV) measurements. Under the optimized conditions, there were linear relationships between the peak currents and the concentrations in the range of 40-1200 μM for AA, 4-200 μM for DA and 4-400 μM for UA, with the limit of detection (LOD) (based on S/N=3) of 0.61, 0.04 and 0.10 μM for AA, DA and UA, respectively. This improved electrochemical performance can be attributed to the synergistic effect of metallic nanoparticles and RGO and the combination of the bimetallic nanoparticles. Furthermore, the practical electroanalytical utility of the sensor was demonstrated by the determination of AA, DA and together with UA in human urine and blood serum samples with satisfactory results. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Simultaneous Electrochemical Detection of Dopamine and Ascorbic Acid Using an Iron Oxide/Reduced Graphene Oxide Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Teo Peik-See

    2014-08-01

    Full Text Available The fabrication of an electrochemical sensor based on an iron oxide/graphene modified glassy carbon electrode (Fe3O4/rGO/GCE and its simultaneous detection of dopamine (DA and ascorbic acid (AA is described here. The Fe3O4/rGO nanocomposite was synthesized via a simple, one step in-situ wet chemical method and characterized by different techniques. The presence of Fe3O4 nanoparticles on the surface of rGO sheets was confirmed by FESEM and TEM images. The electrochemical behavior of Fe3O4/rGO/GCE towards electrocatalytic oxidation of DA was investigated by cyclic voltammetry (CV and differential pulse voltammetry (DPV analysis. The electrochemical studies revealed that the Fe3O4/rGO/GCE dramatically increased the current response against the DA, due to the synergistic effect emerged between Fe3O4 and rGO. This implies that Fe3O4/rGO/GCE could exhibit excellent electrocatalytic activity and remarkable electron transfer kinetics towards the oxidation of DA. Moreover, the modified sensor electrode portrayed sensitivity and selectivity for simultaneous determination of AA and DA. The observed DPVs response linearly depends on AA and DA concentration in the range of 1–9 mM and 0.5–100 µM, with correlation coefficients of 0.995 and 0.996, respectively. The detection limit of (S/N = 3 was found to be 0.42 and 0.12 µM for AA and DA, respectively.

  13. Evaluation of the BYG Carba Test, a New Electrochemical Assay for Rapid Laboratory Detection of Carbapenemase-Producing Enterobacteriaceae.

    Science.gov (United States)

    Bogaerts, Pierre; Yunus, Sami; Massart, Marion; Huang, Te-Din; Glupczynski, Youri

    2016-02-01

    Accurate detection of carbapenemase-producing Enterobacteriaceae (CPE) constitutes a major laboratory diagnostic challenge. We evaluated an electrochemical technique (the BYG Carba test) which allows detection of CPE in less than 35 min. The BYG Carba test was first validated in triplicate against 57 collection isolates with previously characterized β-lactam resistance mechanisms (OXA-48, n = 12; KPC, n = 8; NDM, n = 8; VIM, n = 8; IMP, n = 3; GIM, n = 1; GES-6, n = 1; no carbapenemase, n = 16) and against a panel of 10 isolates obtained from the United Kingdom National External Quality Assessment Service (NEQAS). The test was then evaluated prospectively against 324 isolates referred to the national reference center for suspicion of CPE. The BYG Carba test results were compared with those obtained with the Carba NP test using multiplex PCR sequencing as the gold standard. Of the 57 collection and the 10 NEQAS isolates, all but one GES-6-producing isolate were correctly identified by the Carba BYG test. Among the 324 consecutive Enterobacteriaceae isolates tested prospectively, 146 were confirmed as noncarbapenemase producers by PCR while 178 harbored a carbapenemase gene (OXA-48, n = 117; KPC, n = 25; NDM, n = 23; and VIM, n = 13). Prospectively, in comparison with PCR results, the BYG Carba test displayed 95% sensitivity and 100% specificity versus 89% and 100%, respectively, for the Carba NP test. The BYG Carba test is a novel, rapid, and efficient assay based on an electro-active polymer biosensing technology discriminating between CPE and non-CPE. The precise electrochemical signal (electrochemical impedance variations) allows the establishment of real-time objective measurement and interpretation criteria which should facilitate the accreditation process of this technology.

  14. Multifeature Fusion Vehicle Detection Algorithm Based on Choquet Integral

    Directory of Open Access Journals (Sweden)

    Wenhui Li

    2014-01-01

    Full Text Available Vision-based multivehicle detection plays an important role in Forward Collision Warning Systems (FCWS and Blind Spot Detection Systems (BSDS. The performance of these systems depends on the real-time capability, accuracy, and robustness of vehicle detection methods. To improve the accuracy of vehicle detection algorithm, we propose a multifeature fusion vehicle detection algorithm based on Choquet integral. This algorithm divides the vehicle detection problem into two phases: feature similarity measure and multifeature fusion. In the feature similarity measure phase, we first propose a taillight-based vehicle detection method, and then vehicle taillight feature similarity measure is defined. Second, combining with the definition of Choquet integral, the vehicle symmetry similarity measure and the HOG + AdaBoost feature similarity measure are defined. Finally, these three features are fused together by Choquet integral. Being evaluated on public test collections and our own test images, the experimental results show that our method has achieved effective and robust multivehicle detection in complicated environments. Our method can not only improve the detection rate but also reduce the false alarm rate, which meets the engineering requirements of Advanced Driving Assistance Systems (ADAS.

  15. Electrochemical detection of tobramycin or gentamicin according to the European Pharmacopoeia analytical method.

    Science.gov (United States)

    Ghinami, C; Giuliani, V; Menarini, A; Abballe, F; Travaini, S; Ladisa, T

    2007-01-12

    Tobramycin and gentamicin are two aminoglycosidic antibiotics used in lung infection, ophthalmic treatments as well as in skin infections. Pharmaceutical companies which produce remedies containing tobramycin and gentamicin need an analytical method for their internal quality control. For several years a simple chromatographic method based on anion exchange separation coupled with amperometric detection was proposed for aminoglycosides. This analytical approach was partially used in the last edition of the European Pharmacopoeia (EP) for tobramycin and gentamicin analysis. In fact they use integrated pulsed amperometric detection (IPAD) on a gold electrode while the separation is obtained on a polymeric wide pore reversed phase instead of anion exchange in alkaline conditions. Such coupling seems to be cumbersome and not so easy to realize and to reproduce from one laboratory to another. Besides, the described method lacks some of the details as important as the waveform steps duration. Unfortunately the quality control (QC) laboratories have to use exactly the method described in the EP, so they complained about the troubles. Therefore, the EP authors published recently a paper regarding the guidelines for good practice in the method application, but the suggestion was not yet resolutive. In our work we evaluated the eluent composition and the kind of amperometric cell, work electrode diameter and cell volume. Mainly we optimized the amperometric waveform. In addition, for tobramycin analysis another chromatographic phase was explored in order to achieve better efficiency and to separate all the impurities confirming the effectiveness of the detection. The conditions described in the paper seem to allow the analyst to operate in conformity with the EP method.

  16. Application of peptide nucleic acids containing azobenzene self-assembled electrochemical biosensors in detecting DNA sequences

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Hybridization of peptide nucleic acids probe containing azobenzene (NH2-TNT4, N-PNAs) with DNA was performed by covalently immobilizing of NH2-TNT4 in sequence on the 3-mercaptopropionic acid self-assembled monolayer modified gold electrode with the helps of N-(3-dimethylaminopropy1)-N’-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), and the hybrid was coded as N-PNAs/DNA. Using [Fe(CN)6]4-/3- (1:1) as the electrochemical indicator, the electrochemical properties of the N-PNAs self-assembled monolayer (N-PNAs-SAMs) and N-PNAs/DNA hybridization system under the conditions of before and after UV light irradiation were characterized with cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectra (EIS). Results showed that the redox currents decreased with the increase of irradiation time, suggesting that the ability of the charge transfer on the electrode surface was weakened and the conformation of hybrid system had been changed, and the control of PNAs/DNA hybridization could be realized by UV light irradiation.

  17. Rational design and one-step formation of multifunctional gel transducer for simple fabrication of integrated electrochemical biosensors.

    Science.gov (United States)

    Yu, Ping; Zhou, Heng; Cheng, Hanjun; Qian, Qin; Mao, Lanqun

    2011-07-15

    This study demonstrates a new strategy to simplify the biosensor fabrication and thus minimize the biosensor-to-biosensor deviation through rational design and one-step formation of a multifunctional gel electronic transducer integrating all elements necessitated for efficiently transducing the biorecognition events to signal readout, by using glucose dehydrogenase (GDH) based electrochemical biosensor as an example. To meet the requirements for preparing integrated biosensors and retaining electronic and ionic conductivities for electronically transducing process, ionic liquids (ILs) with enzyme cofactor (i.e., oxidized form of nicotinamide adenine dinucleotide) as the anion were synthesized and used to form a bucky gel with single-walled carbon nanotubes, in which methylene green electrocatalyst was stably encapsulated for the oxidation of nicotinamide adenine dinucleotide. With such kind of rationally designed and one-step-formed multifunctional gel as the electronic transducer, the GDH-based electrochemical biosensors were simply fabricated by polishing the electrodes onto the gel followed by enzyme immobilization. This capability greatly simplifies the biosensor fabrication, prolongs the stability of the biosensors, and, more remarkably, minimizes the biosensor-to-biosensor deviation. The relative standard deviations obtained both with one electrode for the repeated measurements of glucose and with the different electrodes prepared with the same method for the concurrent measurements of glucose with the same concentration were 3.30% (n = 7) and 4.70% (n = 6), respectively. These excellent properties of the multifunctional gel-based biosensors substantially enable them to well-satisfy the pressing need of rapid measurements, for example, environmental monitoring, food analysis, and clinical diagnoses.

  18. 3D CFD Electrochemical and Heat Transfer Model of an Integrated-Planar Solid Oxide Electrolysis Cells

    Energy Technology Data Exchange (ETDEWEB)

    Grant Hawkes; James E. O' Brien

    2008-10-01

    A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created to model high-temperature electrolysis cell performance and steam electrolysis in a new novel integrated planar porous-tube supported solid oxide electrolysis cell (SOEC). The model is of several integrated planar cells attached to a ceramic support tube. This design is being evaluated with modeling at the Idaho National Laboratory. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified for this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, activation over-potential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Mean per-cell area-specific-resistance (ASR) values decrease with increasing current density. Predicted mean outlet hydrogen and steam concentrations vary linearly with current density, as expected. Effects of variations in operating temperature, gas flow rate, cathode and anode exchange current density, and contact resistance from the base case are presented. Contour plots of local electrolyte temperature, current density, and Nernst potential indicated the effects of heat transfer, reaction cooling/heating, and change in local gas composition. Results are discussed for using this design in the electrolysis mode. Discussion of thermal neutral voltage, enthalpy of reaction, hydrogen production, cell thermal efficiency, cell electrical efficiency, and Gibbs free energy are discussed and reported herein.

  19. Electrochemical sensing platform amplified with a nanobiocomposite of L-phenylalanine ammonia-lyase enzyme for the detection of capsaicin.

    Science.gov (United States)

    Sabela, Myalowenkosi I; Mpanza, Thabani; Kanchi, Suvardhan; Sharma, Deepali; Bisetty, Krishna

    2016-09-15

    The present study involves the development of a sensitive electrochemical biosensor for the determination of capsaicin extracted from chilli fruits, based on a novel signal amplification strategy using enzyme technology. For the first time, platinum electrode modified with multiwalled carbon nanotubes where phenylalanine ammonia-lyase enzyme was immobilized using nafion was characterized by attenuated total reflectance infrared spectroscopy, transmittance electron microscopy and thermo-gravimetric analysis supported by computational methods. Cyclic and differential pulse voltammetry measurements were performed to better understand the redox mechanism of capsaicin. The performance of the developed electrochemical biosensor was tested using spiked samples with recoveries ranging from 98.9 to 99.6%. The comparison of the results obtained from bare and modified platinum electrodes revealed the sensitivity of the developed biosensor, having a detection limit (S/N=3) of 0.1863µgmL(-1) and electron transfer rate constant (ks) of 3.02s(-1). Furthermore, adsorption and ligand-enzyme docking studies were carried out to better understand the redox mechanisms supported by density functional theory calculations. These results revealed that capsaicin forms hydrogen bonds with GLU355, GLU541, GLU586, ARG and other amino acids of the hydrophobic channel of the binding sites thereby facilitating the redox reaction for the detection of capsaicin.

  20. Label-Free Electrochemical Detection of the Specific Oligonucleotide Sequence of Dengue Virus Type 1 on Pencil Graphite Electrodes

    Science.gov (United States)

    Souza, Elaine; Nascimento, Gustavo; Santana, Nataly; Ferreira, Danielly; Lima, Manoel; Natividade, Edna; Martins, Danyelly; Lima-Filho, José

    2011-01-01

    A biosensor that relies on the adsorption immobilization of the 18-mer single-stranded nucleic acid related to dengue virus gene 1 on activated pencil graphite was developed. Hybridization between the probe and its complementary oligonucleotides (the target) was investigated by monitoring guanine oxidation by differential pulse voltammetry (DPV). The pencil graphite electrode was made of ordinary pencil lead (type 4B). The polished surface of the working electrode was activated by applying a potential of 1.8 V for 5 min. Afterward, the dengue oligonucleotides probe was immobilized on the activated electrode by applying 0.5 V to the electrode in 0.5 M acetate buffer (pH 5.0) for 5 min. The hybridization process was carried out by incubating at the annealing temperature of the oligonucleotides. A time of five minutes and concentration of 1 μM were found to be the optimal conditions for probe immobilization. The electrochemical detection of annealing between the DNA probe (TS-1P) immobilized on the modified electrode, and the target (TS-1T) was achieved. The target could be quantified in a range from 1 to 40 nM with good linearity and a detection limit of 0.92 nM. The specificity of the electrochemical biosensor was tested using non-complementary sequences of dengue virus 2 and 3. PMID:22163916

  1. Flow Injection Analysis with Electrochemical Detection for Rapid Identification of Platinum-Based Cytostatics and Platinum Chlorides in Water

    Directory of Open Access Journals (Sweden)

    Marketa Kominkova

    2014-02-01

    Full Text Available Platinum-based cytostatics, such as cisplatin, carboplatin or oxaliplatin are widely used agents in the treatment of various types of tumors. Large amounts of these drugs are excreted through the urine of patients into wastewaters in unmetabolised forms. This phenomenon leads to increased amounts of platinum ions in the water environment. The impacts of these pollutants on the water ecosystem are not sufficiently investigated as well as their content in water sources. In order to facilitate the detection of various types of platinum, we have developed a new, rapid, screening flow injection analysis method with electrochemical detection (FIA-ED. Our method, based on monitoring of the changes in electrochemical behavior of analytes, maintained by various pH buffers (Britton-Robinson and phosphate buffer and potential changes (1,000, 1,100 and 1,200 mV offers rapid and cheap selective determination of platinum-based cytostatics and platinum chlorides, which can also be present as contaminants in water environments.

  2. Flow injection analysis with electrochemical detection for rapid identification of platinum-based cytostatics and platinum chlorides in water.

    Science.gov (United States)

    Kominkova, Marketa; Heger, Zbynek; Zitka, Ondrej; Kynicky, Jindrich; Pohanka, Miroslav; Beklova, Miroslava; Adam, Vojtech; Kizek, Rene

    2014-02-04

    Platinum-based cytostatics, such as cisplatin, carboplatin or oxaliplatin are widely used agents in the treatment of various types of tumors. Large amounts of these drugs are excreted through the urine of patients into wastewaters in unmetabolised forms. This phenomenon leads to increased amounts of platinum ions in the water environment. The impacts of these pollutants on the water ecosystem are not sufficiently investigated as well as their content in water sources. In order to facilitate the detection of various types of platinum, we have developed a new, rapid, screening flow injection analysis method with electrochemical detection (FIA-ED). Our method, based on monitoring of the changes in electrochemical behavior of analytes, maintained by various pH buffers (Britton-Robinson and phosphate buffer) and potential changes (1,000, 1,100 and 1,200 mV) offers rapid and cheap selective determination of platinum-based cytostatics and platinum chlorides, which can also be present as contaminants in water environments.

  3. Nanofabrication of Metallic Nanostructures and Integration with Light Detection Devices

    Science.gov (United States)

    Huang, Liang

    Metallic nanostructures have been investigated with various applications especially for integration with light detection devices. The incident light can be manipulated by those nanostructures to enhance light absorption therefor improve device performance. However, previous studies focused on optical design. The electrical properties of these integrated light detection devices have not been fully considered. The photon generated carriers transport and collection are critical for light detection devices as well. An optimized device platform considering from both the optical and electrical aspects to fully utilize these nanostructures is highly desired for future light detection devices. This dissertation targeted on three objectives, beginning with the fabrication process development of various nanostructures on different substrates. High quality nanostructures were achieved with minimum 20nm gap and 45nm line width. The second objective was developing the metallic fishnet nanostructures integrated Schottky contact a-Si solar cell to improve both light absorption and photon generated carrier collection. The fishnet was designed as the light trapping structure and 2D connected top contact to collect carriers. The third objective was developing metallic nanostructures integrated GeSn photodetectors. The H shape nano antennas were integrated on GeSn photodetectors. Multiple resonant absorption peaks at infrared range were observed using spectroscopic ellipsometry. However, there was no obvious photoresponse value improvement of developed solar cells and H shape antennas integrated GeSn photodetectors. For further investigation, interdigitated electrodes integrated GeSn photodetectors were designed. With less carrier transit time, the responsivity value of the integrated Ge0.991Sn0.009 photodetector was 72muA/W at 1.55mum at room temperature which was 6 times higher comparing to device without integration. Meanwhile, with the increased carrier life time by decreasing

  4. Electrochemical detection of benzo(a)pyrene and related DNA damage using DNA/hemin/nafion–graphene biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Yongnian, E-mail: ynni@ncu.edu.cn [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China); Department of Chemistry, Nanchang University, Nanchang 330031 (China); Wang, Pingping; Song, Haiyan [Department of Chemistry, Nanchang University, Nanchang 330031 (China); Lin, Xiaoyun [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China); Department of Chemistry, Nanchang University, Nanchang 330031 (China); Kokot, Serge, E-mail: s.kokot@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, Brisbane 4001 (Australia)

    2014-04-01

    Graphical abstract: A novel electrochemical biosensor, DNA/hemin/nafion–graphene/GCE, was constructed to quantitatively study the DNA damage induced by the metabolite of benzo(a)pyrene in the presence of H{sub 2}O{sub 2}. - Highlights: • Construction of a novel DNA/hemin/nafion-graphene/GCE biosensor. • DNA damage induced by the benzo(a)pyrene metabolite was detected. • DPV analysis of benzo(a)pyrene provided a quantitative estimate of DNA damage. • Hemin/H{sub 2}O{sub 2} system could mimic the cytochrome P450 to metabolize benzo(a)pyrene. - Abstract: A novel electrochemical biosensor, DNA/hemin/nafion–graphene/GCE, was constructed for the analysis of the benzo(a)pyrene PAH, which can produce DNA damage induced by a benzo(a)pyrene (BaP) enzyme-catalytic product. This biosensor was assembled layer-by-layer, and was characterized with the use of cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and atomic force microscopy. Ultimately, it was demonstrated that the hemin/nafion–graphene/GCE was a viable platform for the immobilization of DNA. This DNA biosensor was treated separately in benzo(a)pyrene, hydrogen peroxide (H{sub 2}O{sub 2}) and in their mixture, respectively, and differential pulse voltammetry (DPV) analysis showed that an oxidation peak was apparent after the electrode was immersed in H{sub 2}O{sub 2}. Such experiments indicated that in the presence of H{sub 2}O{sub 2}, hemin could mimic cytochrome P450 to metabolize benzo(a)pyrene, and a voltammogram of its metabolite was recorded. The DNA damage induced by this metabolite was also detected by electrochemical impedance and ultraviolet spectroscopy. Finally, a novel, indirect DPV analytical method for BaP in aqueous solution was developed based on the linear metabolite versus BaP concentration plot; this method provided a new, indirect, quantitative estimate of DNA damage.

  5. Hetero-enzyme-based two-round signal amplification strategy for trace detection of aflatoxin B1 using an electrochemical aptasensor.

    Science.gov (United States)

    Zheng, Wanli; Teng, Jun; Cheng, Lin; Ye, Yingwang; Pan, Daodong; Wu, Jingjing; Xue, Feng; Liu, Guodong; Chen, Wei

    2016-06-15

    An electrochemical aptasensor for trace detection of aflatoxin B1 (AFB1) was developed by using an aptamer as the recognition unit while adopting the telomerase and EXO III based two-round signal amplification strategy as the signal enhancement units. The telomerase amplification was used to elongate the ssDNA probes on the surface of gold nanoparticles, by which the signal response range of the signal-off model electrochemical aptasensor could be correspondingly enlarged. Then, the EXO III amplification was used to hydrolyze the 3'-end of the dsDNA after the recognition of target AFB1, which caused the release of bounded AFB1 into the sensing system, where it participated in the next recognition-sensing cycle. With this two-round signal amplified electrochemical aptasensor, target AFB1 was successfully measured at trace concentrations with excellent detection limit of 0.6*10(-4)ppt and satisfied specificity due to the excellent affinity of the aptamer against AFB1. Based on this designed two-round signal amplification strategy, both the sensing range and detection limit were greatly improved. This proposed ultrasensitive electrochemical aptasensor method was also validated by comparison with the classic instrumental methods. Importantly, this hetero-enzyme based two-round signal amplified electrochemical aptasensor offers a great promising protocol for ultrasensitive detection of AFB1 and other mycotoxins by replacing the core recognition sequence of the aptamer.

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

    Directory of Open Access Journals (Sweden)

    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.

  7. Graphene oxide functionalized with silver@silica-polyethylene glycol hybrid nanoparticles for direct electrochemical detection of quercetin.

    Science.gov (United States)

    Veerapandian, Murugan; Seo, Yeong-Tai; Yun, Kyusik; Lee, Min-Ho

    2014-08-15

    A direct electrochemical detection of quercetin based on functionalized graphene oxide modified on gold-printed circuit board chip was demonstrated in this study. Functionalized graphene oxide materials are prepared by the covalent reaction of graphene oxide with silver@silica-polyethylene glycol nanoparticles (~12.35nm). Functionalized graphene oxide electrode shows a well-defined voltammetric response in phosphate buffered saline and catalyzes the oxidation of quercetin to quinone without the need of an enzyme. Significantly, the functionalized graphene oxide modified electrode exhibited a higher sensitivity than pristine gold-printed circuit board and graphene oxide electrodes, a wide concentration range of 7.5 to 1040nM and detection limit of 3.57nM. Developed biosensor platform is selective toward quercetin in the presence of an interferent molecule.

  8. A disposable immunomagnetic electrochemical sensor based on functionalised magnetic beads on gold surface for the detection of atrazine

    Energy Technology Data Exchange (ETDEWEB)

    Helali, Saloua [Centre de Genie Electrique de Lyon, CEGELY, Ecole Centrale de Lyon, 36 Av. Guy de Collongue, 69134 Ecully Cedex (France) and Unite de Recherche de Physique des Semiconducteurs et Capteurs, IPEST, La Marsa, Tunis (Tunisia)]. E-mail: saloua_helali@yahoo.fr; Martelet, Claude [Centre de Genie Electrique de Lyon, CEGELY, Ecole Centrale de Lyon, 36 Av. Guy de Collongue, 69134 Ecully Cedex (France); Abdelghani, Adnane [Unite de Recherche de Physique des Semiconducteurs et Capteurs, IPEST, La Marsa, Tunis (Tunisia); Maaref, Mhamed Ali [Unite de Recherche de Physique des Semiconducteurs et Capteurs, IPEST, La Marsa, Tunis (Tunisia); Jaffrezic-Renault, Nicole [Centre de Genie Electrique de Lyon, CEGELY, Ecole Centrale de Lyon, 36 Av. Guy de Collongue, 69134 Ecully Cedex (France)

    2006-07-15

    A disposable immunomagnetic electrochemical sensor involving magnetic particles was developed and applied for the detection of atrazine. The sensor was based on a magnetic monolayer of magnetic particles coated with streptavidin, formed on a gold electrode after application of a magnetic field. The magnetic monolayer was characterized using faradaic impedance spectroscopy, cyclic voltammetry and atomic force microscopy (AFM) techniques. The magnetic monolayer formation leads to an important change in constant phase element due to a change in thickness. AFM images show that the magnetic monolayer is formed and is very dense. The atrazine interacts with biotinyl-Fab fragment K47 and the immunoreaction was characterized by impedance spectroscopy. A decrease in electron transfer resistance was observed which could be attributed to rearrangements in the magnetic monolayer. This approach leads to a sensitive detection of atrazine, acting as an antigen, with a good linear response in the range 10-600 ng/ml.

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

    Science.gov (United States)

    Zhu, Rilong; Zhou, Gangqiang; Tang, Fengxia; Wang, Yeyao

    2017-01-01

    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.

  10. Electrochemical Detection of Hydroxylamine via Au-Pt Alloy Nanoparticle-modified Single-walled Carbon Nanotube Electrodes.

    Science.gov (United States)

    Geng, Yanfang; Ko, Euna; Tran, Van-Khue; Chung, Woo Sung; Park, Chan Ho; Kim, Min Ki; Jin, Ga Hyun; Seong, Gi Hun

    2017-01-01

    In the present study, we developed an electrochemical sensor for highly sensitive detection of hydroxylamine using Au-Pt alloy nanoparticles. Au-Pt alloy nanoparticles were electrochemically deposited on a working electrode made of single-walled carbon nanotubes. The framework composition in the Au-Pt alloy nanoparticle was easily controlled by adjusting the Au(3+):Pt(4+) composition ratio in the precursor solution. Morphological and chemical characterizations of the resulting Au-Pt alloy nanoparticles were performed using field emission scanning electron microscopy, X-ray diffraction, and energy dispersion X-ray spectroscopy. When the Au(3+):Pt(4+) ratio in the precursor solution was 1:5, the ratio of Au:Pt atom in alloy nanoparticle was about 6:4. Au60Pt40 alloy nanoparticles were found to have the optimum synthetic ratio for hydroxylamine detection. The electrocatalytic performance of Au-Pt alloy nanoparticles in the presence of hydroxylamine was also characterized using cyclic voltammetry, differential pulse voltammetry, and chronoamperometry. In the chronoamperometric detection of hydroxylamine, the sensor exhibited a detection limit of 0.80 μM (S/N = 3) and a high sensitivity of 184 μA mM(-1) cm(-2). Moreover, the amperometric response of the sensor in 1 mM hydroxylamine was stable for a long time (450 s). Long-term stability tests showed that the current responses to hydroxylamine were 96, 91 and 85% of the initial signal value after storage for 5, 10, and 20 days, respectively.

  11. Electrochemical biosensors for detection of point mutation based on surface ligation reaction and oligonucleotides modified gold nanoparticles.

    Science.gov (United States)

    Wang, Qing; Yang, Lijuan; Yang, Xiaohai; Wang, Kemin; He, Leiliang; Zhu, Jinqing

    2011-03-04

    An electrochemical method for point mutation detection based on surface ligation reaction and oligonucleotides (ODNs) modified gold nanoparticles (AuNPs) was demonstrated. Point mutation identification was achieved using Escherichia coli DNA ligase. This system for point mutation detection relied on a sandwich assay comprising capture ODN immobilized on Au electrodes, target ODN and ligation ODN. Because of the sequence-specific surface reactions of E. coli DNA ligase, the ligation ODN covalently linked to the capture ODN only in the presence of a perfectly complementary target ODN. The presence of ligation products on Au electrode was detected using chronocoulometry through hybridization with reporter ODN modified AuNPs. The use of AuNPs improved the sensitivity of chronocoulometry in this approach, a detection limit of 0.9 pM complementary ODN was obtained. For single base mismatched ODN (smODN), a negligible signal was observed. Even if the concentration ratio of complementary ODN to smODN was decreased to 1:1000, a detectable signal was observed. This work may provide a specific, sensitive and cost-efficient approach for point mutant detection.

  12. Direct electrochemical detection of PCR product based on charge transfer through DNA

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hongtao; ZHANG Zhijie; JU Huangxian

    2005-01-01

    @@ Human genome project and genetic identification for inherited diseases will definitely have a profound impact on the diagnosis of diseases[1], which calls for rapid and accurate assays of DNA. Among different types of sensors, electrochemical DNA biosensors offer a promising alternative means[2,3]. Recent efforts to elucidate the mechanism of charge transfer in DNA have demonstrated that the charge transfer is sensitive to the perturbation in base stack[4,5]. Long-range charge transfer in DNA therefore has been showing great potential application in the development of DNA-based biosensors, especially in the study of single nucleotide polymorphs[7―10].

  13. Colorimetric and electrochemical Pb2+ detection by imine-bridged tetrathiafulvalene-pyridine derivatives

    Institute of Scientific and Technical Information of China (English)

    TUNG; ChenHo

    2009-01-01

    Imine-bridged TTF-π-pyridine derivatives, 2NTTF, 3NTTF and 4NTTF, were synthesized and the cation-binding study was performed. It is noted that with the addition of the micromolar concentration of Pb2+ to the solution, these compounds display remarkable changes in solution color, 1H NMR spectra and electrochemical properties. The nitrogen atom of the imine-bridge in 2NTTF not only serves as a π-conjugated spacer but also participates in the sensing and coordinating properties.

  14. Solid state synthesis of copper tungstate nanoparticles and its electrochemical detection of 4-chlorophenol

    Science.gov (United States)

    Muthamizh, S.; Suresh, R.; Giribabu, K.; Manigandan, R.; Kumar, S. Praveen; Munusamy, S.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

    2014-04-01

    Copper tungstate (CuWO4) nanoparticles were prepared by Solid state synthesis. The CuWO4 nanoparticles were synthesized by reacting 1:1 mole ratio of copper chloride and sodium tungstate. The XRD pattern reveals that the synthesized CuWO4 has anorthic (triclinic) structure. In addition, the average grain size, lattice parameter values were also calculated using XRD data. The FT-IR analysis confirm the presence of Cu-O and W-O bonds in CuWO4 nanoparticles. The electrochemical sensing behavior of CuWO4 nanoparticles towards 4-chlorophenol was investigated using cyclic voltammetry.

  15. Electrochemical branched-DNA assay for polymerase chain reaction-free detection and quantification of oncogenes in messenger RNA.

    Science.gov (United States)

    Lee, Ai-Cheng; Dai, Ziyu; Chen, Baowei; Wu, Hong; Wang, Jun; Zhang, Aiguo; Zhang, Lurong; Lim, Tit-Meng; Lin, Yuehe

    2008-12-15

    We describe a novel electrochemical branched-DNA (bDNA) assay for polymerase chain reaction (PCR)-free detection and quantification of p185 BCR-ABL leukemia fusion transcripts in the population of messenger ribonucleic acid (mRNA) extracted from cell lines. The bDNA amplifier carrying high loading of alkaline phosphatase (ALP) tracers was used to amplify the target signal. The targets were captured on microplate well surfaces through cooperative sandwich hybridization prior to the labeling of bDNA. The activity of captured ALP was monitored by square-wave voltammetric (SWV) analysis of the electroactive enzymatic product in the presence of 1-naphthyl phosphate. The voltammetric characteristics of substrate and enzymatic product as well as the parameters of SWV analysis were systematically optimized. A detection limit of 1 fM (1 x 10(-19) mol of target transcripts in 100 microL) and a 3-order-wide dynamic range of target concentration were achieved by the electrochemical bDNA assay. Such limit corresponded to approximately 17 fg of the p185 BCR-ABL fusion transcripts. The specificity and sensitivity of assay enabled direct detection of target transcripts in as little as 4.6 ng of mRNA population without PCR amplification. In combination with the use of a well-quantified standard, the electrochemical bDNA assay was capable of direct use for a PCR-free quantitative analysis of target transcripts in mRNA population. A mean transcript copy number of 62,900/ng of mRNA was determined, which was at least 50-fold higher than that of real-time quantitative PCR (qPCR). The finding was consistent with the underestimation of targets by qPCR reported earlier. In addition, the unique design based on bDNA technology increases the assay specificity as only the p185 BCR-ABL fusion transcripts will respond to the detection. The approach thus provides a simple, sensitive, accurate, and quantitative tool alternative to the qPCR for early disease diagnosis.

  16. Sensitive electrochemical aptamer cytosensor for highly specific detection of cancer cells based on the hybrid nanoelectrocatalysts and enzyme for signal amplification.

    Science.gov (United States)

    Sun, Duanping; Lu, Jing; Zhong, Yuwen; Yu, Yanyan; Wang, Yu; Zhang, Beibei; Chen, Zuanguang

    2016-01-15

    Human cancer is becoming a leading cause of death in the world and the development of a straightforward strategy for early detection of cancer is urgently required. Herein, a sandwich-type electrochemical aptamer cytosensor was developed for detection of human liver hepatocellular carcinoma cells (HepG2) based on the hybrid nanoelectrocatalysts and enzyme for signal amplification. The thiolated TLS11a aptamers were used as a selective bio-recognition element, attached to the gold nanoparticles (AuNPs) modified the glassy carbon electrode (GCE) surface. Meanwhile, the electrochemical nanoprobes were fabricated through the G-quadruplex/hemin/aptamer complexes and horseradish peroxidase (HRP) immobilized on the surfaces of Au@Pd core-shell nanoparticle-modified magnetic Fe3O4/MnO2 beads (Fe3O4/MnO2/Au@Pd). After the target cells were captured, the hybrid nanoprobes were further assembled to form an aptamer-cell-nanoprobes sandwich-like system on the electrode surface. Then, hybrid Fe3O4/MnO2/Au@Pd nanoelectrocatalysts, G-quadruplex/hemin HRP-mimicking DNAzymes and the natural HRP enzyme efficiently catalyzed the oxidation of hydroquinone (HQ) with H2O2, amplifying the electrochemical signals and improving the detection sensitivity. This electrochemical cytosensor delivered a wide detection range of 1×10(2)-1×10(7)cellsmL(-1), high sensitivity with a low detection limit of 15cellsmL(-1), good selectivity and repeatability. Finally, an electrochemical reductive desorption method was performed to break gold-thiol bond and desorb the components on the AuNPs/GCE for regenerating the cytosensor. These results have demonstrated that the electrochemical cytosensor has the potential to be a feasible tool for cost-effective cancer cell detection in early cancer diagnosis.

  17. Lab-on-a-disc platform for screening of genetically modified E. coli cells via cell-free electrochemical detection of p-Coumaric acid

    DEFF Research Database (Denmark)

    Sanger, Kuldeep; Zor, Kinga; Jendresen, Christian Bille

    2017-01-01

    obtained from the electrochemical measurements showed good correlation with high performance liquid chromatographic analysis. The developed LoD system offers fast and easy detection of pHCA, enabling screening of genetically modified organisms based on the quantity of produced secondary metabolites....... filtration and electrochemical detection units, the sample filtration was performed by rotating the disc using a programmable closed-loop stepper motor. The electrodes, patterned on plastic substrate, were connected through a printed circuit board to the slip ring using a robust magnetic clamping system...

  18. An Electrochromatography Chip with Integrated Waveguides for UV Absorbance Detection

    DEFF Research Database (Denmark)

    Gustafsson, Omar; Mogensen, Klaus Bo; Ohlsson, Pelle Daniel

    2008-01-01

    A silicon-based microchip for electrochromatographic separations is presented. Apart from a microfluidic network, the microchip has integrated UV-transparent waveguides for detection and integrated couplers for optical fibers on the chip, yielding the most complete chromatography microchip to date...... in terms of the integration of optical components. The microfluidic network and the optical components are fabricated in a single etching step in silicon and subsequently thermally oxidized. The separation column consists of a regular array of microfabricated solid support structures with a monolayer...

  19. Integrating the multifunction necessary for electrochemical energy storage into energy- and size-scalable ultraporous nanoarchitectures

    Science.gov (United States)

    Rolison, Debra

    2012-02-01

    Designing high performance energy-storage devices that combine nanometric feature size with well-wired transport paths requires an architectural perspective. We chose carbon aerogel-like nanofoam papers as attractive plug-and-play electrode substrates because of such desirable properties as high specific surface area, electronic conductivity, and through-connected pore structure. Achieving this blend of desirable properties requires an optimal balance of critical architectural features: (1) open, 3D interconnected macropores sized at 100 to 300 nm (a difficult-to-obtain size range in porous carbons) and (2) pore walls of a size that reduce dead weight and volume (preferably ca. 20-nm wall thickness for 100- to 300-nm voids), yet retain mechanical strength and flexibility without compromising electronic conductivity (preferably ca. 20 S/cm). Carbon nanofoam papers provide a low cost and scalable nanocomposite that exists within this ``Goldilocks zone'' of desirable properties and which has catalyzed breakthroughs in our work with asymmetric electrochemical capacitors, air cathodes for metal/air batteries, lithium-ion batteries, 3D batteries, and semifuel cells. New charge-storage or catalytic functionality is imparted to internal carbon walls simply by transporting reactants within the 3D macroporous. Self-limiting modification strategies allow us to incorporate conformal, nanoscopic ``paints'' of metal (Mn, Ti, Ru, Fe) or polymer (redox-active or electron insulating) or to specifically adsorb metal nanoparticles (Pt, Au, Pd, Ag) throughout the macroscopic thickness (0.07 to 0.3 mm) of carbon nanofoam papers as dictated by the requirements of a specific end application. For instance, modification with 10-nm MnOx increases the mass-, geometric-, and volume-normalized capacitance (2- to 10-fold) relative to the native carbon nanofoam without significantly altering its high-rate character and provides a structure that can be used in an asymmetric electrochemical

  20. Hazards of Secondary Bromadiolone Intoxications Evaluated using High-performance Liquid Chromatography with Electrochemical Detection

    Directory of Open Access Journals (Sweden)

    René Kizek

    2007-07-01

    Full Text Available This study reported on the possibility of intoxications of non-target wild animalsassociated with use of bromadiolone as the active component of rodenticides withanticoagulation effects. A laboratory test was done with earthworms were exposed tobromadiolone-containing granules under the conditions specified in the modified OECD207 guideline. No mortality of earthworms was observed during the fourteen days longexposure. When the earthworms from the above test became a part of the diet of commonvoles in the following experiment, no mortality of consumers was observed too. However,electrochemical analysis revealed higher levels of bromadiolone in tissues fromearthworms as well as common voles compared to control animals. There were determinedcomparable levels of bromadiolone in the liver tissue of common voles after primary(2.34±0.10 μg/g and secondary (2.20±0.53 μg/g intoxication. Therefore, the risk ofsecondary intoxication of small mammalian species feeding on bromadiolone-containing earthworms is the same as of primary intoxication through baited granules. Bromadiolone bio-accumulation in the food chain was monitored using the newly developed analytical procedure based on the use of a liquid chromatography coupled with electrochemical detector (HPLC-ED. The HPLC-ED method allowed to determine the levels of bromadiolone in biological samples and is therefore suitable for examining the environmental hazards of this substance.

  1. Plasmonic Imaging of Electrochemical Reactions of Single Nanoparticles.

    Science.gov (United States)

    Fang, Yimin; Wang, Hui; Yu, Hui; Liu, Xianwei; Wang, Wei; Chen, Hong-Yuan; Tao, N J

    2016-11-15

    systems and nanoscale materials with high throughput. The plasmonic approach has two imaging modes: electrochemical current imaging and interfacial impedance imaging. The former images local electrochemical current associated with electrochemical reactions (faradic current), and the latter maps local interfacial impedance, including nonfaradic contributions (e.g., double layer charging). The plasmonic imaging technique can perform voltammetry (cyclic or square wave) in an analogous manner to the traditional electrochemical methods. It can also be integrated with bright field, dark field, and fluorescence imaging capabilities in one optical setup to provide additional capabilities. To date the plasmonic imaging technique has found various applications, including mapping of heterogeneous surface reactions, analysis of trace substances, detection of catalytic reactions, and measurement of graphene quantum capacitance. The plasmonic and other emerging optical imaging techniques (e.g., dark field and fluorescence microscopy), together with the scanning probe-based electrochemical imaging and single nanoparticle analysis techniques, provide new capabilities for one to study single nanoparticle electrochemistry with unprecedented spatial and temporal resolutions. In this Account, we focus on imaging of electrochemical reactions at single nanoparticles.

  2. Review of Electrochemical Detection Methods on Trace Heavy Metals%痕量重金属电化学检测综述

    Institute of Scientific and Technical Information of China (English)

    朱果逸

    2013-01-01

    检测水环境重金属的发展方向为现场、快速、实时、在线、连续和自动化测量.由此传感器的微型化、集成化和分析仪器的便携化、自动化是发展的必然趋势.本文综述了电化学分析重金属的方法、仪器.实现多种元素的同时测量,与其他分析方法相比,电化学溶出伏安法的仪器设备简单,便于携带和操作,灵敏度和准确度高,选择性好,运行费用低,体积小,易于实现微型、在线、快速和自动化检测.%Detection of heavy metals in water environment development direction for the scene,fast,real-time,online,continuous and automated measurements.Thus miniaturization of sensors,integration and portable analytical instruments,automation is the inevitable trend of development.In this paper,a method of electrochemical analysis of heavy metals,instruments.Achieve a variety of elements measured simultaneously with other analytical methods,electrochemical stripping voltammetry of simple equipment,easy to carry and operate,sensitivity and accuracy,selectivity,low cost,small size,easy to implement micro,online,fast and automated testing.

  3. An electrochemical biosensor for rapid detection of E. coli O157:H7 with highly efficient bi-functional glucose oxidase-polydopamine nanocomposites and Prussian blue modified screen-printed interdigitated electrodes.

    Science.gov (United States)

    Xu, Meng; Wang, Ronghui; Li, Yanbin

    2016-09-21

    The presence of pathogenic bacteria in foods has always been a great threat to the wellbeing of people and the revenue of food manufacturers. Therefore, the demand for advanced detection methods that can sensitively and rapidly detect these pathogens has been of great importance. This study reports an electrochemical biosensor for rapid detection of E. coli O157:H7 with the integration of bifunctional glucose oxidase (GOx)-polydopamine (PDA) based polymeric nanocomposites (PMNCs) and Prussian blue (PB) modified screen-printed interdigitated microelectrodes (SP-IDMEs). The core-shell magnetic beads (MBs)-GOx@PDA PMNCs were first synthesized by the self-polymerization of dopamine (DA). Gold nanoparticles (AuNPs) were dispersed on the surface of PMNCs through biochemical synthesis to achieve further highly efficient adsorption of antibodies (ABs) and GOx. The final product ABs/GOxext/AuNPs/MBs-GOx@PDA PMNCs served as the carrier to separate target bacteria from food matrices as well as the amplifier for electrochemical measurement. The unbound PMNCs were separated by a filtration step and transferred into glucose solution to allow the enzymatic reaction to occur. The change of the current response was measured with an electrochemical detector using PB-modified SP-IDMEs. The constructed biosensor has been proven to be able to detect E. coli O157:H7 with the detection limit of 10(2) cfu ml(-1). The bifunctional PMNCs contain a high load of enzyme and can optimally utilize the binding sites on bacterial cells, which efficiently amplify the signals for measurement. The biosensor in this study exhibited good specificity, reproducibility, and stability and is expected to have a great impact on applications in the detection of foodborne pathogens.

  4. Investigation of the utility of complementary electrochemical detection techniques to examine the in vitro affinity of bacterial flagellins for a toll-like receptor 5 biosensor.

    Science.gov (United States)

    She, Zhe; Topping, Kristin; Shamsi, Mohtashim H; Wang, Nan; Chan, Nora W C; Kraatz, Heinz-Bernhard

    2015-04-21

    An initial investigation of the fabrication of a novel biosensor utilizing toll-like receptor 5 (TLR5) has been conducted. The detection assay using this sensor platform has been carried out using two complementary electrochemical techniques. The electrochemical properties of the modified bare gold surface following TLR5 immobilization were characterized. The electrochemical response to changes in the sensor film resistance and electron charge-transfer permittivity triggered by independent exposures to flagellins from Salmonella typhimurium (S. typhimurium) and Bacillus subtilis (B. subtilis) were examined and observed. The quantified film resistance data gathered using electrochemical impedance spectroscopy (EIS) over a macroscopic scale are in significant agreement with the corresponding electron charge-transfer permittivity measured locally by scanning electrochemical microscopy (SECM). Unlike other sensors that exploit pathogen recognition elements, TLR5 biosensors have the potential to carry out broad-spectrum detection of flagellated bacterial pathogens in near real time. This broad-spectrum detection platform is a significant step toward the development of fast, inexpensive clinical tools for early warning diagnoses and immediate on-site treatment.

  5. 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.

  6. Improved electrochemical detection of biogenic amines in Aplysia using base-hydrolyzed cellulose-coated carbon fiber microelectrodes.

    Science.gov (United States)

    Marinesco, Stéphane; Carew, Thomas J

    2002-05-30

    A major challenge with electrochemical techniques in vivo, using carbon-fiber microelectrodes, is to achieve sufficient sensitivity to detect the low concentrations of transmitters released by neurons. In particular, when an electrode is inserted into living tissue, its sensitivity is usually substantially decreased as a result of the degradation of the carbon surface by proteins. Here, we show that this decrease can be significantly attenuated by coating the electrode with cellulose acetate. The cellulose film offers a steric barrier that prevents macromolecules from diffusing to the carbon surface and its porosity can be progressively increased by controlled hydrolysis. We compared different cellulose-coated electrodes, either non-hydrolysed or hydrolyzed, in 0.08 N KOH for 10-30 min. We found that dopamine and serotonin detection was blocked by non-hydrolysed cellulose films, but that hydrolysis restored optimal detection similar to uncoated electrodes. Moreover, cellulose films (hydrolyzed for 20 min) significantly diminished electrode degradation in vivo and allowed reliable detection of fast concentration changes with coated electrodes is approximately 20 min with our protocol and carbon fiber electrodes prepared with this method offer improved sensitivity for the detection of biogenic amines.

  7. Analysis of amphetamines in urine with liquid-liquid extraction by capillary electrophoresis with simultaneous electrochemical and electrochemiluminescence detection.

    Science.gov (United States)

    Sun, Jinying; Xu, Xiaoyu; Wang, Chunyan; You, Tianyan

    2008-10-01

    Amphetamines including methamphetamine, 3,4-methylenedioxyamphetamine and 3,4-methylenedioxymethamphetamine were separated and detected by CE using simultaneous electrochemical (EC) and electrochemiluminescence (ECL) detection (CE-EC/ECL). Factors that influenced the separation and detection performance, such as the detection potential, the pH value and concentration of the running buffer, the separation voltage and the pH of the detection buffer, were investigated. LODs of 3.3x10(-8) mol/L (0.16 fmol), 1.6x10(-7) mol/L (0.78 fmol) and 3.3x10(-8) mol/L (0.16 fmol) were obtained for methamphetamine, 3,4-methylenedioxyamphetamine and 3,4-methylenedioxymethamphetamine, respectively. For practical application, a liquid-liquid extraction with ethyl acetate procedure was developed for urine sample pretreatment and extraction efficiencies higher than 90% were obtained. The established simultaneous CE-EC/ECL was successfully applied for urine sample analysis.

  8. Label-free electrochemical aptasensor constructed by layer-by-layer technology for sensitive and selective detection of cancer cells.

    Science.gov (United States)

    Wang, Tianshu; Liu, Jiyang; Gu, Xiaoxiao; Li, Dan; Wang, Jin; Wang, Erkang

    2015-07-02

    Here, a cytosensor was constructed with ferrocene-appended poly(allylamine hydrochloride) (Fc-PAH) functionalized graphene (Fc-PAH-G), poly(sodium-p-styrenesulfonate) (PSS) and aptamer (AS1411) by layer-by-layer assembly technology. The hybrid nanocomposite Fc-PAH-G not only brings probes on the electrode and also promotes electron transfer between the probes and the substrate electrode. Meanwhile, LBL technology provides more effective probes to enhance amplified signal for improving the sensitivity of the detection. While AS1411 forming G-quardruplex structure and binding cancer cells, the current response of the sensing electrode decreased due to the insulating properties of cellular membrane. Differential pulse voltammetry (DPV) was performed to investigate the electrochemical detection of HeLa cells attributing to its sensitivity of the current signal change. The as-prepared aptasensor showed a high sensitivity and good stability, a widely detection range from 10 to 10(6) cells/mL with a detection limit as low as 10 cells/mL for the detection of cancer cells.

  9. The electrochemical oxidation of homocysteine at boron-doped diamond electrodes with application to HPLC amperometric detection.

    Science.gov (United States)

    Chailapakul, O; Siangproh, W; Sarada, B V; Terashima, C; Rao, Tata N; Tryk, D A; Fujishima, A

    2002-09-01

    The electrochemical oxidation of homocysteine was studied at as-deposited and anodized (oxidized) boron-doped diamond (BDD) thin film electrodes with cyclic voltammetry, flow injection analysis and high-pressure liquid chromatography with amperometric detection. At anodized boron-doped diamond electrodes, highly reproducible, well-defined cyclic voltammograms for homocysteine oxidation were obtained in acidic media, while as-deposited diamond did not provide a detectable signal. In alkaline media, however, the oxidation response was obtained both at as-deposited and anodized diamond electrodes. The potential sweep rate dependence of homocysteine oxidation (peak currents for 1 mM homocysteine linearly proportional to v(1/2), within the range of 0.01 to 0.3 V s(-1)) indicates that the oxidation involves a diffusing species, with negligible adsorption on the BDD surface at this concentration. In the flow system, BDD exhibited a highly reproducible amperometric response, with a peak variation less than 2%. An extremely low detection limit (1 nM) was obtained at 1.6 V vs. Ag/AgCl. In addition, the determination of homocysteine in a standard mixture with aminothiols and disulfide compounds by means of isocratic reverse-phase HPLC with amperometric detection at diamond electrodes has been investigated. The results showed excellent separation, with a detection limit of 1 pmol and a linear range of three orders of magnitude.

  10. Novel electrochemical immune sensor based on Hep-PGA-PPy nanoparticles for detection of α-Fetoprotein in whole blood.

    Science.gov (United States)

    Xu, Tingting; Chi, Bo; Gao, Jian; Chu, Meilin; Fan, Wenlu; Yi, Meihui; Xu, Hong; Mao, Chun

    2017-07-18

    A simple and accurate immune sensor for quantitative detection of α-Fetoprotein (AFP) was developed based on the immobilization of antigen on the surface of Hep-PGA-PPy nanoparticles modified glassy carbon electrodes (GCE). The obtained Hep-PGA-PPy nanoparticles were characterized by fourier transform infrared (FT-IR) spectra and transmission electron microscopy (TEM). And the blood compatibility of Hep-PGA-PPy nanoparticles was investigated by in vitro coagulation tests, hemolysis assay and whole blood adhesion tests. Combining the conductive property of polypyrrole (PPy) and the biocompatibility of heparin (Hep), the Hep-PGA-PPy nanoparticles could improve not only the anti-biofouling effect the electrode, but also improved the electrochemical properties of the immune sensor. Under optimal conditions, the proposed immune sensor could detect AFP in a linear range from 0.1 to 100 ng mL(-1) with a detection limit of 0.099 ng mL(-1) at the signal-to-noise ratio of 3, and it also possessed good reproducibility and storage stability. Furthermore, the detection of AFP in five human blood samples also showed satisfactory accuracy with low relative errors. Thus, the developed immune sensor which showed acceptable reproducibility, selectivity, stability and accuracy could be potentially used for the detection of whole blood samples directly. Copyright © 2017. Published by Elsevier B.V.

  11. Improved electrochemical performances of polyaniline nanotubes-poly-L-lysine composite for label-free impedance detection of DNA hybridization

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A sensitive label-free DNA hybridization biosensing platform was fabricated based on the synergistic effect of polyaniline nanotubes (PANInt) and poly-L-lysine (pLys).The composite of pLys and PANInt was coated onto the carbon paste electrode (CPE) to form a uniform and very stable nanocomposite membrane.The pLys in the composite film not only acts as a membrane to retain good electron transfer capability of PANInt even at physiological pH,but also possesses fine biocompatibility for bio-analytes.DNA probes with negatively charged phosphate groups were readily linked to the positively charged pLys surface due to the strong electrostatic affinity.The synergistic effect of PANInt and pLys could significantly enhance the sensitivity of DNA hybridization recognition.The phosphinothricin acetyltransferase (PAT) gene fragment from transgenic corn and the polymerase chain reaction amplification of the terminator of nopaline synthase gene from the real sample of a kind of transgenic soybean were detected by this DNA electrochemical biosensor via label-free impedance method.This stable composite gives convenient permselectivity properties as a transducer material for the design of modern electrochemical impedance biosensor using [Fe(CN)6]3-/4as an indicator.

  12. One pot electrochemical synthesis of poly(melamine) entrapped gold nanoparticles composite for sensitive and low level detection of catechol.

    Science.gov (United States)

    Palanisamy, Selvakumar; Ramaraj, Sayee Kannan; Chen, Shen-Ming; Chiu, Te-Wei; Velusamy, Vijayalakshmi; Yang, Thomas C K; Chen, Tse-Wei; Selvam, Sonadevi

    2016-12-29

    A simple and cost effective synthesis of nanomaterials with advanced physical and chemical properties have received much attention to the researchers, and is of interest to the researchers from different disciplines. In the present work, we report a simple and one pot electrochemical synthesis of poly(melamine) entrapped gold nanoparticles (PM-AuNPs) composite. The PM-AuNPs composite was prepared by a single step electrochemical method, wherein the AuNPs and PM were simultaneously fabricated on the electrode surface. The as-prepared materials were characterized by various physicochemical methods. The PM-AuNPs composite modified electrode was used as an electrocatalyst for oxidation of catechol (CC) due to its well-defined redox behavior and enhanced electro-oxidation ability towards CC than other modified electrodes. Under optimized conditions, the differential pulse voltammetry (DPV) was used for the determination of CC. The DPV response of CC was linear over the concentration ranging from 0.5 to 175.5μM with a detection limit of 0.011μM. The PM-AuNPs composite modified electrode exhibits the high selectivity in the presence of range of potentially interfering compounds including dihydroxybenzene isomers. The sensor shows excellent practicality in CC containing water samples, which reveals the potential ability of PM-AuNPs composite modified electrode towards the determination of CC in real samples.

  13. A compact analytical formalism for current transients in electrochemical systems

    CERN Document Server

    Nair, Pradeep R

    2011-01-01

    Micro and nanostructured electrodes form an integral part of a wide variety of electrochemical systems for biomolecule detection, batteries, solar cells, scanning electrochemical microscopy, etc. Given the complexity of the electrode structures, the Butler-Volmer formalism of redox reactions, and the diffusion transport of redox species, it is hardly surprising that only a few problems are amenable to closed form, compact analytical solutions. While numerical solutions are widely used, it is often difficult to integrate the insights gained to the design and optimization of electrochemical systems. In this article, we develop a comprehensive analytical formalism for current transients that not only anticipate the response of complex electrode structures to complicated voltammetry measurements, but also intuitively interpret diverse experiments such as redox detection of molecules at nanogap electrodes, scanning electrochemical microscopy, etc. The results from the analytical model, well supported through detai...

  14. An Electrochemical Strategy using Multifunctional Nanoconjugates for Efficient Simultaneous Detection of Escherichia coli O157: H7 and Vibrio cholerae O1

    Science.gov (United States)

    Li, Yan; Xiong, Ya; Fang, Lichao; Jiang, Lili; Huang, Hui; Deng, Jun; Liang, Wenbin; Zheng, Junsong

    2017-01-01

    The rapid and accurate quantification of the pathogenic bacteria is extremely critical to decrease the bacterial infections in all areas related to health and safety. We have developed an electrochemical strategy for simultaneous ultrasensitive detection of E. coli O157:H7 and Vibrio cholerae O1. This approach was based on the specific immune recognition of different pathogenic bacteria by multifunctional nanoconjugates and subsequent signal amplification. By employing the proposed biosensor, the concentrations of these pathogenic bacteria could be established on a single interface in a single run with improved sensitivity and accuracy. The successful approach of the simultaneous detection and quantification of two bacteria by an electrochemical biosensor demonstrated here could be readily expanded for the estimation of a variety of other pathogenic bacteria, proteins, and nucleotides. Because of their high sensitivity, electrochemical biosensors may represent a new avenue for early diagnosis of diseases. PMID:28382165

  15. Integrated polymer waveguides for absorbance detection in chemical analysis systems

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; El-Ali, Jamil; Wolff, Anders

    2003-01-01

    . The emphasis of this paper is on the signal-to-noise ratio of the detection and its relation to the sensitivity. Two absorbance cells with an optical path length of 100 μm and 1000 μm were characterized and compared in terms of sensitivity, limit of detection and effective path length for measurements......A chemical analysis system for absorbance detection with integrated polymer waveguides is reported for the first time. The fabrication procedure relies on structuring of a single layer of the photoresist SU-8, so both the microfluidic channel network and the optical components, which include planar...

  16. Bioluminescent bioreporter integrated circuit devices and methods for detecting ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, Michael L [Knoxville, TN; Paulus, Michael J [Knoxville, TN; Sayler, Gary S [Blaine, TN; Applegate, Bruce M [West Lafayette, IN; Ripp, Steven A [Knoxville, TN

    2007-04-24

    Monolithic bioelectronic devices for the detection of ammonia includes a microorganism that metabolizes ammonia and which harbors a lux gene fused with a heterologous promoter gene stably incorporated into the chromosome of the microorganism and an Optical Application Specific Integrated Circuit (OASIC). The microorganism is generally a bacterium.

  17. Detection of orbital angular momentum using a photonic integrated circuit.

    Science.gov (United States)

    Rui, Guanghao; Gu, Bing; Cui, Yiping; Zhan, Qiwen

    2016-06-20

    Orbital angular momentum (OAM) state of photons offer an attractive additional degree of freedom that has found a variety of applications. Measurement of OAM state, which is a critical task of these applications, demands photonic integrated devices for improved fidelity, miniaturization, and reconfiguration. Here we report the design of a silicon-integrated OAM receiver that is capable of detecting distinct and variable OAM states. Furthermore, the reconfiguration capability of the detector is achieved by applying voltage to the GeSe film to form gratings with alternate states. The resonant wavelength for arbitrary OAM state is demonstrated to be tunable in a quasi-linear manner through adjusting the duty cycle of the gratings. This work provides a viable approach for the realization of a compact integrated OAM detection device with enhanced functionality that may find important applications in optical communications and information processing with OAM states.

  18. Simple and fast screening of G-quadruplex ligands with electrochemical detection system.

    Science.gov (United States)

    Fan, Qiongxuan; Li, Chao; Tao, Yaqin; Mao, Xiaoxia; Li, Genxi

    2016-11-01

    Small molecules that may facilitate and stabilize the formation of G-quadruplexes can be used for cancer treatments, because the G-quadruplex structure can inhibit the activity of telomerase, an enzyme over-expressed in many cancer cells. Therefore, there is considerable interest in developing a simple and high-performance method for screening small molecules binding to G-quadruplex. Here, we have designed a simple electrochemical approach to screen such ligands based on the fact that the formation and stabilization of G-quadruplex by ligand may inhibit electron transfer of redox species to electrode surface. As a proof-of-concept study, two types of classical G-quadruplex ligands, TMPyP4 and BRACO-19, are studied in this work, which demonstrates that this method is fast and robust and it may be applied to screen G-quadruplex ligands for anticancer drugs testing and design in the future.

  19. Correlated Electrochemical and Optical Detection Reveals the Chemical Reactivity of Individual Silver Nanoparticles.

    Science.gov (United States)

    Brasiliense, Vitor; Patel, Anisha N; Martinez-Marrades, Ariadna; Shi, Jian; Chen, Yong; Combellas, Catherine; Tessier, Gilles; Kanoufi, Frédéric

    2016-03-16

    Electrochemical (EC) impacts of single nanoparticles (NPs) on an ultramicroelectrode are coupled with optics to identify chemical processes at the level of individual NPs. While the EC signals characterize the charge transfer process, the optical monitoring gives a complementary picture of the transport and chemical transformation of the NPs. This is illustrated in the case of electrodissolution of Ag NPs. In the simplest case, the optically monitored dissolution of individual NPs is synchronized with individual EC spikes. Optics then validates in situ the concept of EC nanoimpacts for sizing and counting of NPs. Chemical complexity is introduced by using a precipitating agent, SCN(-), which tunes the overall electrodissolution kinetics. Particularly, the charge transfer and dissolution steps occur sequentially as the synchronicity between the EC and optical signals is lost. This demonstrates the level of complexity that can be revealed from such electrochemistry/optics coupling.

  20. Colorimetric Integrated PCR Protocol for Rapid Detection of Vibrio parahaemolyticus

    Science.gov (United States)

    Cheng, Kewen; Pan, Daodong; Teng, Jun; Yao, Li; Ye, Yingwang; Xue, Feng; Xia, Fan; Chen, Wei

    2016-01-01

    Rapid detection of pathogens is of great significance for food safety and disease diagnosis. A new colorimetric method for rapid and easy detection of Vibrio parahaemolyticus (V. parahaemolyticus or Vp) has been developed in this research. A specific sequence was designed and integrated with the forward primer for molecular detection of Vp. This specific sequence was tested and treated as the horseradish peroxidase (HRP)-mimicking DNAzyme and could be amplified during the polymerase chain reaction (PCR) process. The products of PCR including the sequence of HRP-mimicking DNAzyme could produce the distinguished color in the presence of catalysis substrates. The optical signal of the catalysis reaction, which is in a linear relationship with the initial template of Vp, could be determined with the naked eye or measured with Ultraviolet-visible (UV-vis) for qualitative and quantitative detections, respectively. Based on the optical signal intensity, rapid and easy detection of Vp was successfully achieved with satisfied sensitivity and specificity. Furthermore, the detection of tdh, trh, tlh and toxR virulence genes of two Vp species (Vp 33847 and Vp 17802) were all performed successfully with this developed colorimetric integrated PCR protocol, which demonstrated potential applicability for the rapid detection of other bacteria. PMID:27690041

  1. Colorimetric Integrated PCR Protocol for Rapid Detection of Vibrio parahaemolyticus

    Directory of Open Access Journals (Sweden)

    Kewen Cheng

    2016-09-01

    Full Text Available Rapid detection of pathogens is of great significance for food safety and disease diagnosis. A new colorimetric method for rapid and easy detection of Vibrio parahaemolyticus (V. parahaemolyticus or Vp has been developed in this research. A specific sequence was designed and integrated with the forward primer for molecular detection of Vp. This specific sequence was tested and treated as the horseradish peroxidase (HRP-mimicking DNAzyme and could be amplified during the polymerase chain reaction (PCR process. The products of PCR including the sequence of HRP-mimicking DNAzyme could produce the distinguished color in the presence of catalysis substrates. The optical signal of the catalysis reaction, which is in a linear relationship with the initial template of Vp, could be determined with the naked eye or measured with Ultraviolet-visible (UV-vis for qualitative and quantitative detections, respectively. Based on the optical signal intensity, rapid and easy detection of Vp was successfully achieved with satisfied sensitivity and specificity. Furthermore, the detection of tdh, trh, tlh and toxR virulence genes of two Vp species (Vp 33847 and Vp 17802 were all performed successfully with this developed colorimetric integrated PCR protocol, which demonstrated potential applicability for the rapid detection of other bacteria.

  2. Ultrasensitive electrochemical immunosensor based on horseradish peroxidase (HRP)-loaded silica-poly(acrylic acid) brushes for protein biomarker detection.

    Science.gov (United States)

    Zhao, Yan; Zheng, Yiqun; Kong, Rongmei; Xia, Lian; Qu, Fengli

    2016-01-15

    We report an ultrasensitive electrochemical immunosensor designed for the detection of protein biomarkers using horseradish peroxidase (HRP)-loaded silica-poly(acrylic acid) brushes (SiO2-SPAABs) as labels. HRP could be efficiently and stably accommodated in the three-dimensional architecture of the SiO2-SPAABs and the SiO2-SPAABs-HRP exhibited high catalytic performance towards o-phenylenediamine (OPD) oxidation in the presence of H2O2, which resulted in significant differential pulse voltammetric (DPV) response change and color change. Using human IgG (HIgG) as a model analyte, a sandwich-type immunosensor was constructed. In particular, graphene oxide (GO) and SiO2-SPAABs-HRP were used to immobilize capture antibody (Ab1) and bind a layer of detection antibody (Ab2), respectively. The current biosensor exhibited a good linear response of HIgG from 100pg/mL to 100μg/mL with a detection limit of 50pg/mL (S/N=5). The sensitivity was 6.70-fold higher than the conventional enzyme-linked immunosorbent assays. The immunosensor results were validated through the detection of HIgG in serum samples.

  3. Effective seed-assisted synthesis of gold nanoparticles anchored nitrogen-doped graphene for electrochemical detection of glucose and dopamine.

    Science.gov (United States)

    Thanh, Tran Duy; Balamurugan, Jayaraman; Lee, Seung Hee; Kim, Nam Hoon; Lee, Joong Hee

    2016-07-15

    A novel gold nanoparticle-anchored nitrogen-doped graphene (AuNP/NG) nanohybrid was synthesized through a seed-assisted growth method, as an effective electrocatalyst for glucose and dopamine detection. The AuNP/NG nanohybrids exhibited high sensitivity and selectivity toward glucose and dopamine sensing applications. The as-synthesized nanohybrids exhibited excellent catalytic activity toward glucose, with a linear response throughout the concentration range from 40μM to 16.1mM, a detection limit of 12μM, and a short response time (∼ 10s). It also exhibited an excellent response toward DA, with a wide detection range from 30nM to 48μM, a low detection limit of 10nM, and a short response time (∼ 8s). Furthermore, it also showed long-term stability and high selectivity for the target analytes. These results imply that such nanohybrids show a great potential for electrochemical biosensing application.

  4. Simultaneous determination of three curcuminoids in Curcuma longa L. by high performance liquid chromatography coupled with electrochemical detection

    Institute of Scientific and Technical Information of China (English)

    Yuling Long; Wenpeng Zhang; Fang Wang; Zilin Chen

    2014-01-01

    A novel method for analysis of three active components curcumin, demethoxycurcumin and bisdemethoxycurcumin in Curcuma longa L. was developed by HPLC coupled with electrochemical detection. Three curcuminoids were well separated on a C18 column and detected with high sensitivity. A mobile phase containing acetonitrile and 10 mM Na2HPO4-H3PO4 (pH 5.0) (50:50, v/v) was used. Good linearity was obtained in the range of 0.208-41.6, 0.197-39.4, and 0.227-114μM for curcumin, demethoxycurcumin and bisdemethoxycurcumin respectively. The limit of detection reached up to 10 ? 8 M, which was lower than that by UV detection. The relative standard deviations (RSDs) ranged from 1.06%to 1.88%for intra-day precision and from 4.30%to 5.79%for inter-day precision, respectively. The proposed method has been applied in real herb sample and recoveries ranging from 86.3%to 111%were obtained.

  5. Single domain antibody coated gold nanoparticles as enhancer for Clostridium difficile toxin detection by electrochemical impedance immunosensors

    Science.gov (United States)

    Zhu, Zanzan; Shi, Lianfa; Feng, Hanping; Zhou, H. Susan

    2016-01-01

    This work presents a sandwich-type electrochemical impedance immunosensor for detecting Clostridium difficile toxin A (TcdA) and toxin B (TcdB). Single domain antibody conjugated gold nanoparticles were applied to amplify the detection signal. Gold nanoparticles (Au NPs) were characterized by transmission electron microscopy and UV–vis spectra. The electron transfer resistance (Ret) of the working electrode surface was used as a parameter in the measurement of the biosensor. With the increase of the concentration of toxins from 1 pg/mL to 100 pg/mL, a linear relationship was observed between the relative electron transfer resistance and toxin concentration. In addition, the detection signal was enhanced due to the amplification effect. The limit of detection for TcdA and TcdB was found to be 0.61 pg/mL and 0.60 pg/mL respectively at a signal-to-noise ratio of 3 (S/N = 3). This method is simple, fast and ultrasensitive, thus possesses a great potential for clinical applications in the future. PMID:25460611

  6. Biomarker differences between cadaveric grafts used in human orthotopic liver transplantation as identified by coulometric electrochemical array detection (CEAD) metabolomics.

    Science.gov (United States)

    Perera, M Thamara P R; Higdon, Roger; Richards, Douglas A; Silva, Michael A; Murphy, Nick; Kolker, Eugene; Mirza, Darius F

    2014-12-01

    Metabolomics in systems biology research unravels intracellular metabolic changes by high throughput methods, but such studies focusing on liver transplantation (LT) are limited. Microdialysate samples of liver grafts from donors after circulatory death (DCD; n=13) and brain death (DBD; n=27) during cold storage and post-reperfusion phase were analyzed through coulometric electrochemical array detection (CEAD) for identification of key metabolomics changes. Metabolite peak differences between the graft types at cold phase, post-reperfusion trends, and in failed allografts, were identified against reference chromatograms. In the cold phase, xanthine, uric acid, and kynurenine were overexpressed in DCD by 3-fold, and 3-nitrotyrosine (3-NT) and 4-hydroxy-3-methoxymandelic acid (HMMA) in DBD by 2-fold (pidentification of overexpression of kynurenine in DCD grafts and in failed allografts is unique. Further studies should examine kynurenine as a potential biomarker predicting graft function, its causation, and actions on subsequent clinical outcomes.

  7. Biofunctionalization of Polyoxometalates with DNA Primers, Their Use in the Polymerase Chain Reaction (PCR) and Electrochemical Detection of PCR Products.

    Science.gov (United States)

    Debela, Ahmed M; Ortiz, Mayreli; Beni, Valerio; Thorimbert, Serge; Lesage, Denis; Cole, Richard B; O'Sullivan, Ciara K; Hasenknopf, Bernold

    2015-12-01

    The bioconjugation of polyoxometalates (POMs), which are inorganic metal oxido clusters, to DNA strands to obtain functional labeled DNA primers and their potential use in electrochemical detection have been investigated. Activated monooxoacylated polyoxotungstates [SiW11 O39 {Sn(CH2 )2 CO}](8-) and [P2 W17 O61 {Sn(CH2 )2 CO}](6-) have been used to link to a 5'-NH2 terminated 21-mer DNA forward primer through amide coupling. The functionalized primer was characterized by using a battery of techniques, including electrophoresis, mass spectrometry, as well as IR and Raman spectroscopy. The functionality of the POM-labeled primers was demonstrated through hybridization with a surface-immobilized probe. Finally, the labeled primers were successfully used in the polymerase chain reaction (PCR) and the PCR products were characterized by using electrophoresis.

  8. Electrochemical hydride generation atomic fluorescence spectrometry for detection of tin in canned foods using polyaniline-modified lead cathode

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Xianjuan [Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Gan Wuer, E-mail: wgan@ustc.edu.cn [Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wan Lingzhong; Deng Yun; Yang Qinghua; He Youzhao [Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2010-12-15

    An electrochemical hydride generation system with polyaniline-modified lead cathode was developed for tin determination by coupling with atomic fluorescence spectrometry. The tin fluorescence signal intensity was improved evidently as the polyaniline membrane could facilitate the transformation process from atomic tin to the SnH{sub 4} and prevent the aggradation of Sn atom on Pb electrode surface. The effects of experimental parameters and interferences have been studied. The limit of detection (LOD) was 1.5 ng mL{sup -1} (3{sigma}) and the relative standard deviation (RSD) was 3.3% for 11 consecutive measurements of 50 ng mL{sup -1} Sn(IV) standard solution.

  9. Self-assembled monolayers of stearic imidazoline on copper electrodes detected using electrochemical measurements, XPS, molecular simulation and FTIR

    Institute of Scientific and Technical Information of China (English)

    LIU XiuYu; MA HouYi; MIAO Shuai; ZHOU Min

    2009-01-01

    A type of imidazoline inhibitor was synthesized using stearic acid and diethylenetriamine (DETA) as raw materials. Self-assembled monolayers (SAMs) of stearic imidazoline (IM) were prepared on copper surface. The copper electrode modified by IM was detected by electrochemical impedance spectros-copy (EIS), Tafel polarization curves, X-ray photoelectron spectroscopy (XPS) and Fourial transform reflection spectroscopy (FTIR). The biggest inhibition efficiency for copper corrosion of IM was 99% in NaCI solution according to EIS results. The XPS results provided evidence that the IM was adsorbed on copper surface. The theoretical calculations of molecular simulation supported the experimental re-sults and showed that the IM molecules were tilted at an angle to the copper surface.

  10. Label-free electrochemical aptasensor constructed by layer-by-layer technology for sensitive and selective detection of cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Tianshu [College of Physics, Jilin University, Changchun, Jilin 130012 (China); State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); Liu, Jiyang; Gu, Xiaoxiao; Li, Dan [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); Wang, Jin, E-mail: jin.wang.1@stonybrook.edu [College of Physics, Jilin University, Changchun, Jilin 130012 (China); State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China); Department of Chemistry, Physics and Applied Mathematics, State University of New York at Stony Brook, Stony Brook, NY 11794-3400 (United States); Wang, Erkang, E-mail: ekwang@ciac.jl.cn [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022 (China)

    2015-07-02

    Highlights: • Fc-PAH was modified on the surface of graphene to prepare hybid nanocomposite (Fc-PAH-G). • A cytosensor was constructed with Fc-PAH-G, PSS and aptamer AS1411 by LBL technology. • The sensing interface introduced more redox probe and enhanced current signal on electrode. • The sensor showed a detection range of 10–10{sup 6} cells/mL with a detection limit of 10 cells/mL. - Abstract: Here, a cytosensor was constructed with ferrocene-appended poly(allylamine hydrochloride) (Fc-PAH) functionalized graphene (Fc-PAH-G), poly(sodium-p-styrenesulfonate) (PSS) and aptamer (AS1411) by layer-by-layer assembly technology. The hybrid nanocomposite Fc-PAH-G not only brings probes on the electrode and also promotes electron transfer between the probes and the substrate electrode. Meanwhile, LBL technology provides more effective probes to enhance amplified signal for improving the sensitivity of the detection. While AS1411 forming G-quardruplex structure and binding cancer cells, the current response of the sensing electrode decreased due to the insulating properties of cellular membrane. Differential pulse voltammetry (DPV) was performed to investigate the electrochemical detection of HeLa cells attributing to its sensitivity of the current signal change. The as-prepared aptasensor showed a high sensitivity and good stability, a widely detection range from 10 to 10{sup 6} cells/mL with a detection limit as low as 10 cells/mL for the detection of cancer cells.

  11. Electrodeposition of gold-platinum alloy nanoparticles on carbon nanotubes as electrochemical sensing interface for sensitive detection of tumor marker

    Energy Technology Data Exchange (ETDEWEB)

    Li Ya [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Yuan Ruo, E-mail: yuanruo@swu.edu.cn [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Chai Yaqin; Song Zhongju [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)

    2011-07-30

    Graphical abstract: Electrodeposition of gold-platinum alloy (Au-PtNPs) on carbon nanotubes as electrochemical sensing interface and HRP as blocking agent for the fabrication of high sensitive immunosensor. Display Omitted Highlights: > In this work, we proposed a novel electrochemical sensing surface. > The sensing surface possessed larger electro-active areas and higher conductivity due to the introduction of MWCNTs. > The signal could be amplified effectively by synergetic catalysis effect of Au-PtNPs and HRP towards the reduction of H{sub 2}O{sub 2}. > Biomolecules could be immobilized on the surface of Au-PtNPs tightly with the bioactivity kept well. > The simple fabrication method provided a new potential for the future development of practical devices for clinical diagnosis application. - Abstract: A novel electrochemical sensing interface, electrodeposition of gold-platinum alloy nanoparticles (Au-PtNPs) on carbon nanotubes, was proposed and used to fabricate a label-free amperometric immunosensor. On the one hand, the multiwalled carbon nanotubes (MWCNTs) could increase active area of the electrode and enhance the electron transfer ability between the electrode and redox probe; on the other hand, the Au-PtNPs not only could be used to assemble biomolecules with bioactivity kept well, but also could further facilitate the shuttle of electrons. In the meanwhile, horseradish peroxidase (HRP) instead of bovine serum albumin (BSA) was employed to block the possible remaining active sites and avoid the nonspecific adsorption. With the synergetic catalysis effect of Au-PtNPs and HRP towards the reduction of hydrogen peroxide (H{sub 2}O{sub 2}), the signal could be amplified and the sensitivity could be enhanced. Using alpha-fetoprotein (AFP) as model analyte, the fabricated immunosensor exhibited two wide linear ranges in the concentration ranges of 0.5-20 ng mL{sup -1} and 20-200 ng mL{sup -1} with a detection limit of 0.17 ng mL{sup -1} at a signal-to-noise of

  12. A Study on Tannic Acid-doped Polypyrrole Films on Gold Electrodes for Selective Electrochemical Detection of Dopamine

    Directory of Open Access Journals (Sweden)

    Shouzhuo Yao

    2005-04-01

    Full Text Available Tannic acid-doped polypyrrole (PPY/TA films have been grown on goldelectrodes for selective electrochemical detection of dopamine (DA. Electrochemicalquartz crystal microbalance (EQCM studies revealed that, in vivid contrast toperchlorate-doped polypyrrole films (PPY/ClO4-, the redox switching of PPY/TA filmsin aqueous solutions involved only cation transport if the solution pH was greater than3~4. The PPY/TA Au electrodes also exhibited attractive permselectivity forelectroactive cations, namely, effectively blocking the electrochemical reactions ofanionic ferricyanide and ascorbic acid (AA while well retaining the electrochemicalactivities of hexaammineruthenium (III and dopamine as cationic species. A 500 HzPPY/TA film could effectively block the redox current of up to 5.0 mM AA. Thecoexistence of ascorbic acid in the measurement solution notably enhanced the currentsignal for dopamine oxidation, due probably to the chemical regeneration of dopaminethrough an ascorbic acid-catalyzed reduction of the electro-oxidation product ofdopamine (EC’ mechanism, and the greatest amplification was found at an ascorbic acidconcentration of 1.0 mM. The differential pulse voltammetry peak current for DAoxidation was linear with DA concentration in the range of 0 to 10 μM, with sensitivityof 0.125 and 0.268 μA/μM, as well as lower detection limit of 2.0 and 0.3 μM in a PBSsolution without AA and with 1.0 mM coexisting AA, respectively.

  13. Electrochemical detection of vascular endothelial growth factors (VEGFs) using VEGF antibody fragments modified Au NPs/ITO electrode.

    Science.gov (United States)

    Kim, Gang-Il; Kim, Kyung-Woo; Oh, Min-Kyu; Sung, Yun-Mo

    2010-03-15

    A new electrochemical technique for the detection of vascular endothelial growth factors (VEGFs) as a cancer-related biomarker is presented in this paper. Gold nanoparticles (Au NPs) were self-assembled onto an indium tin oxide (ITO) electrode to prepare a modified sandwich type electrochemical immunoassay platform. VEGF antibodies were cleaved into two half-fragments by 2-mercaptoethylamine-HCl (2-MEA) and the fragments were immobilized onto the Au NP substrates by their thiol groups. Through this strategy, randomly oriented attachment of antibodies was prevented which frequently occurs in a general use of whole antibody and reduces the number of available sites for the attachment of target molecules. VEGF target molecules were applied to the immunoelectrodes and they combined with the antibody fragments covering the Au NP electrode, forming antigen-antibody complexes. Then, ferrocene-tagged antibodies, which release electrons under a proper applied potential, were added to the system and they combined with the VEGF molecules pre-attached to the antibody fragments. The redox current of ferrocene measured by the differential pulse voltammetry (DPV) increased almost linearly from 1.27 x 10(-4) to 4.17 x 10(-4)A according to the increase in the concentration of the VEGF target molecules from 100 to 600 pg/ml. The measured current values represent the concentration of the VEGF since they are proportional to the number of ferrocene molecules which is in turn proportional to the concentration of VEGF target molecules. Using this modified sandwich immunoassay with the Au NP/ITO electrode, VEGFs as low as 100 pg/ml were detected with high specificity.

  14. Poly(zwitterionic liquids) functionalized polypyrrole/graphene oxide nanosheets for electrochemically detecting dopamine at low concentration

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Hui; Liang, Jiachen; Ji, Chunguang; Zhang, Haifeng; Pei, Qi; Zhang, Yuyang; Zhang, Yu [Liaoning Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036 (China); Hisaeda, Yoshio [Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Song, Xi-Ming, E-mail: songlab@lnu.edu.cn [Liaoning Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036 (China); Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan)

    2016-08-01

    Poly(3-(1-vinylimidazolium-3-yl)propane-1-sulfonate) (PVIPS), a novel kind of poly(zwitterionic liquids) (PZILs) containing both imidazolium cation and sulfonate anion, was successfully modified on the surface of polypyrrole/graphene oxide nanosheets (PPy/GO) by covalent bonding. The obtained novel PZILs functionalized PPy/GO nanosheets (PVIPS/PPy/GO) modified glassy carbon electrode (GCE) presented the excellent electrochemical catalytic activity towards dopamine (DA) with high stability, sensitivity, selectivity and wide linear range (40–1220 nM), especially having a lower detection limit (17.3 nM). The excellent analytical performance is attributed to the strongly negative charges on the surface of modified GCE in aqueous solution, which is different from conventional poly(ionic liquids) modified GCE. DA cations could be quickly enriched on the electrode surface by electrostatic interaction in solution due to the existence of −SO{sub 3}{sup −} groups with negative charge at the end of pendant groups in zwitterionic PVIPS, resulting in a change of the electrons transmission mode in the oxidation of DA, that is, from a typical diffusion-controlled process at conventional poly(1-vinyl-3-ethylimidazole bromide) (PVEIB)/PPy/GO modified GCE to a typical surface-controlled process. - Graphical Abstract: Novel poly(zwitterionic liquids) functionalized polypyrrole/graphene oxide nanosheets were successfully synthesized and presented an excellent performance for determination to DA. Display Omitted - Highlights: • Zwitterionic PVIPS functionalized PPy/GO nanosheets were successfully synthesized. • Their surface charge property has been obviously changed to electronegativity. • The excellent electrochemical catalytic activities towards DA were achieved. • −SO{sub 3}{sup −} groups with negative charge changed the transmission mode of electrons. • PVIPS/PPy/GO can act as an electrode material for detecting DA at low concentration.