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Sample records for resonance based immunosensor

  1. High-sensitive nonlinear detection of steroids by resonant double grating waveguide structures-based immunosensors

    NASA Astrophysics Data System (ADS)

    Muriano, Alejandro; Salvador, J.-Pablo; Galve, Roger; Marco, M.-Pilar; Thayil K. N., Anisha; Loza-Alvarez, Pablo; Soria, Silvia

    2011-01-01

    We report the non linear fluorescence real-time detection of methylboldenone, an androgenic anabolic steroid used illegally as growth promoter based on a resonant sensing chip: a double grating waveguide structure. The limit of detection of this synthetic steroid is two orders of magnitude lower than the Minimum Required Performance Limit required by the World Anti-Doping Agency. The immunoreagents have been have been immobilized onto the surface of the resonant sensor after being activated with phosphonohexanoic acid spacers. The developed immunosensor presents great potential as a robust sensing device for fast and early detection of illegal dopants and food contaminants.

  2. Side-polished fiber immunosensor based on surface plasmon resonance for detection of Legionella pneumophila

    NASA Astrophysics Data System (ADS)

    Tsao, Yu-Chia; Yang, Yi-Wen; Tsai, Woo-Hu; Yan, Tsong-Rong

    2008-02-01

    Side-polished fiber immunosensor based on surface plasmon resonance (SPR) onto self-assembled protein A layer was proposed for the detection of Legionella pneumophila. A self-assembled protein A layer on gold (Au) surface was fabricated by adsorbing a mixture of 11-mercaptoundecanoic acid (MUA) and activated by N-Ethyl-N'-(3-dimethylaminopropyl) carbodiimide/ N-Hydroxysuccinimide (EDC/NHS). The formation of self-assembled protein A and gold layer on side-polished surface and the binding of antibody and antigen in series were confirmed by SPR response on spectrum. The binding protein A layer can improve the sensitivity, which indirectly supports the configurations that antibody layer is immobilized on the binding protein A layer with a well-ordered orientation. The surface morphology analyses of self-assembled protein A layer on Au substrate and monoclonal antibody against L. pneumophila immobilized on protein A were demonstrated by SPR dip shifts on optical spectrum analyzer. The SPR fiber immunosensor for detection of L. pneumophila was developed and the detection limit was 10 CFU/ml with the SPR dip shift in wavelength from 1070 to 1105nm. The current fabrication technique of a SPR immunosensor using optical fiber for the detection of Legionella pneumophila could be applied to construct other biosensor.

  3. Surface plasmon resonance immunosensor for human cardiac troponin T based on self-assembled monolayer.

    PubMed

    Dutra, Rosa Fireman; Mendes, Renata Kelly; Lins da Silva, Valdinete; Kubota, Lauro Tatsuo

    2007-04-11

    The cardiac troponin T (cTnT) is specific biomarker important for trials of acute myocardial infarctions (AMI). In this paper, a SPR sensor in real time to detect the biomarker was developed on a commercially available surface plasmon resonance AUTOLAB SPIRIT. The cTnT receptor molecule was covalently immobilized on a gold substrate via a self-assembled monolayer (SAM) of thiols by using cysteamine-coupling chemistry. This biosensor presented a linear response range for cTnT between 0.05 and 4.5 ng/mL (r=0.997, p<0.01) with a good reproducibility (CV=4.4%). The effect of the cysteamine (CYS) concentrations on the SAM coated gold sensor was studied as a function of the amount of the immobilized cTnT monoclonal antibodies. Analysis using serum samples undiluted was carried out at room temperature showing a well agreement with the ECLIA methods and the sensor surface could be regenerated by using a solution of 1% (w/v) sodium dodecyl sulphate (SDS) without losing the sensor immunoreactivity. These studies open new perspectives of using SAM to develop regenerable immunosensor with a good reproducibility allowing its use in the clinical applications.

  4. Direct detection of orchid viruses using nanorod-based fiber optic particle plasmon resonance immunosensor.

    PubMed

    Lin, Hsing-Ying; Huang, Chen-Han; Lu, Sin-Hong; Kuo, I-Ting; Chau, Lai-Kwan

    2014-01-15

    A fiber optic particle plasmon resonance (FOPPR) immunosensor is developed for label-free detection of orchid viruses that use gold nanorods (AuNRs) as the sensing material. The AuNRs are employed to create a near-infrared sensing window to solve the color interference problem of sample matrix for direct sensing of target analyte. This work cannot be achieved using gold nanospheres (AuNSs) because the signal of sample color absorption largely overlaps the signal of molecular recognition events in the visible spectrum, making the signal interpretation much more difficult. The AuNRs are immobilized on the unclad fiber core surface, and functionalized by antibodies which can specifically recognize the corresponding Cymbidium mosaic virus (CymMV) or Odontoglossum ringspot virus (ORSV) for rapid viral infection diagnosis. The refractive index resolution of the AuNR-FOPPR sensor is estimated to be 8×10(-6) RIU. The limits of detection (LODs) for CymMV and ORSV in leaf saps are 48 and 42 pg/mL, respectively, which are better than the LODs of 1200 pg/mL for both viruses obtained by enzyme-linked immunosorbent assay (ELISA). Exploiting the AuNR-FOPPR sensing strategy not only solves the color interference problem encountered by using AuNSs, but provides faster analysis, better reproducibility, and lower detection limit than ELISA. The sensor can distinguish between healthy and infected orchids in 10 min, and can further provide the quantitative analysis of infection level. It is potentially applicable to the quality control of orchid cultivation industry, but not limited to this, especially for creating special spectral sensing window for particular samples.

  5. Rapid and sensitive detection of microcystin by immunosensor based on nuclear magnetic resonance.

    PubMed

    Ma, Wei; Chen, Wei; Qiao, Ruirui; Liu, Chunyan; Yang, Chunhui; Li, Zhuokun; Xu, Dinghua; Peng, Chifang; Jin, Zhengyu; Xu, Chuanlai; Zhu, Shuifang; Wang, Libing

    2009-09-15

    A stable and sensitive toxin residues immunosensor based on the relaxation of magnetic nanoparticles was developed. The method was performed in one reaction and offered sensitive, fast detection of target toxin residues in water. The target analyte, microcystin-LR (MC-LR) in Tai lake water, competed with the antigens on the surface of the magnetic nanoparticles and then influenced the formation of aggregates of the magnetic nanoparticles. Accordingly, the magnetic relaxation time of the magnetic nanoparticles was changed under the effect of the target analyte. The calibration curve was deduced at different concentrations of the target analyte. The limit of detection (LOD) of MC-LR was 0.6 ng g(-1) and the detection range was 1-18 ng g(-1). Another important feature of the developed method was the easy operation: only two steps were needed (1) to mix the magnetic nanoparticle solution with the sample solution and (2) read the results through the instrument. Therefore, the developed method may be a useful tool for toxin residues sensing and may find widespread applications.

  6. Fluorescence-based reversible immunosensors

    NASA Astrophysics Data System (ADS)

    Issachar, David; Rao, Srivasta V.; Ho, Winston; Kempen, Lothar U.; Wang, Allan Z.; Gasca, Rebecca; Lieberman, Robert A.

    1999-02-01

    All immunosensors currently described in literature are irreversible. Intelligent Optical Systems, Inc. has developed a revolutionary method for producing reversible immunosensors. In this method, the antibody and a labeled analog (structurally and functionally similar to the antigen) are coimmobilized on the sensor surface. Under equilibrium conditions, the labeled analog interacts with immobilized antibody to produce a sensor response. However, in the presence of antigen (analyte), the equilibrium is disturbed as the analyte competes for the binding sites of the immobilized antibody. This produces a measurable sensor response. The equilibrium is shifted back by washing the analyte away with a wash buffer, and the bound analog interacts with the immobilized antibody. Polarization and intensity based measurements are used to design the analog. Photoinduced electron transfer is used to create fluorescent analogs that provide enhancements in fluorescence intensity that can be measured. This principle can be extended to the detection of bacteria.

  7. A Surface Plasmon Resonance-Based Immunosensors for Sensitive Detection of Heroin

    NASA Astrophysics Data System (ADS)

    Wu, Zhong-cheng; Chen, Wen-ge; Wang, Lian-chao; Ge, Yu; Yu, Cheng-duan; Fang, Ting-jian

    2000-12-01

    A simple technique for sensitive detection of heroin based on surface-plasmon-resonance has been theoretically and experimentally investigated. The experiment was realized by using an anti-MO monoclonal antibody and a morphine (MO)-bovine serum albumin (MO-BSA) conjugate (antigen). The reason for using MO-BSA in the detection of heroine was also discussed. MO-BSA was immobilized on a gold thin film of SPR sensor chip by physical adsorption. The configuration of the device is allowed to be further miniaturized, which is required for the construction of a portable SPR device in the application of in-situ analysis.

  8. Development of a sensitive surface plasmon resonance immunosensor for detection of 2,4-dinitrotoluene with a novel oligo (ethylene glycol)-based sensor surface.

    PubMed

    Nagatomo, Kazutaka; Kawaguchi, Toshikazu; Miura, Norio; Toko, Kiyoshi; Matsumoto, Kiyoshi

    2009-09-15

    A surface plasmon resonance (SPR) immunosensor for detection of 2,4-dinitrotoluene (2,4-DNT), which is a signature compound of 2,4,6-trinitrotoluene-related explosives, was developed by using a novel oligo (ethylene glycol) (OEG)-based sensor surface. A rabbit polyclonal antibody against 2,4-DNT (anti-DNPh-KLH-400 antibody) was prepared, and the avidity for 2,4-DNT and recognition capability were investigated by indirect competitive ELISA. The sensor surface was fabricated by immobilizing a 2,4-DNT analog onto an OEG-based self-assembled monolayer formed on a gold surface via an OEG linker. The fabricated surface was characterized by Fourier-transform infrared-refractive absorption spectrometry (FTIR-RAS). The immunosensing of 2,4-DNT is based on the indirect competitive principle, in which the immunoreaction between the anti-DNPh-KLH-400 antibody and 2,4-DNT on the sensor surface was inhibited in the presence of free 2,4-DNT in solution. The limit of detection for the immunosensor, calculated as three times the standard deviation of a blank value, was 20 pg mL(-1), and the linear dynamic range was found to be between 1 and 100 ng mL(-1). Additionally, the fabricated OEG-based surface effectively prevented non-specific adsorption of proteins, and the specific response to anti-DNPh-KLH-400 antibody was maintained for more than 30 measurement cycles.

  9. Enhanced optical immunosensor based on surface plasmon resonance for determination of transferrin.

    PubMed

    Liu, Xia; Sun, Ying; Song, Daqian; Zhang, Qinglin; Tian, Yuan; Zhang, Hanqi

    2006-01-15

    Wavelength modulation surface plasmon resonance biosensors (SPR) using colloidal Au nanoparticles and double-linker sensing membrane enhancement are reported for determination of transferrin. The 2-mercaptoethylamine (MEA) was immobilized on the biosensor surface with traditional amine coupling method. The interaction between colloidal Au nanoparticles and MEA was investigated. The anti-transferrin was immobilized on the biosensor surface prepared with staphylococcal protein A (SPA). The interaction of the antibody and antigen was monitored in real time. The good response was obtained in the concentration range 1-20, 0.1-20 and 0.05-20 microg/mL for directly immune assay, double-linker assay and colloidal Au-amplified assay. The result clearly demonstrates that these methods may obtain significantly enhancement of sensitivity for the wavelength modulation SPR biosensor.

  10. Surface plasmon resonance immunosensor for cortisol and cortisone determination.

    PubMed

    Frasconi, Marco; Mazzarino, Monica; Botrè, Francesco; Mazzei, Franco

    2009-08-01

    In this paper, we present a surface-plasmon-resonance-based immunosensor for the real-time detection of cortisol and cortisone levels in urine and saliva samples. The method proposed here is simple, rapid, economic, sensitive, robust, and reproducible thanks also to the special features of the polycarboxylate-hydrogel-based coatings used for the antibody immobilization. The sensor surface displays a high level of stability during repeated regeneration and affinity reaction cycles. The immunosensor shows high specificity for cortisol and cortisone; furthermore, no significant interferences from other steroids with a similar chemical structure have been observed. The suitability of the hydrogel coating for the prevention of nonspecific binding is also investigated. A good correlation is noticed between the results obtained by the proposed method and the reference liquid chromatography/tandem mass spectrometry method for the analysis of cortisol and cortisone in urine and saliva samples. Standard curves for the detection of cortisol and cortisone in saliva and urine are characterized by a detection limit less than 10 microg l(-1), sufficiently sensitive for both clinical and forensic use.

  11. Ring-Resonator/Sol-Gel Interferometric Immunosensor

    NASA Technical Reports Server (NTRS)

    Bearman, Gregory; Cohen, David

    2007-01-01

    A proposed biosensing system would be based on a combination of (1) a sensing volume containing antibodies immobilized in a sol-gel matrix and (2) an optical interferometer having a ring resonator configuration. The antibodies would be specific to an antigen species that one seeks to detect. In the ring resonator of the proposed system, light would make multiple passes through the sensing volume, affording greater interaction length and, hence, greater antibody- detection sensitivity.

  12. Development of a label-free immunosensor based on surface plasmon resonance technique for the detection of anti-Leishmania infantum antibodies in canine serum.

    PubMed

    Souto, Dênio E P; Silva, Jussara V; Martins, Helen R; Reis, Alexandre B; Luz, Rita C S; Kubota, Lauro T; Damos, Flávio S

    2013-08-15

    In this work, a surface plasmon resonance (SPR) immunosensor was developed using an 11-mercaptoundecanoic acid (11-MUA) modified gold SPR sensor chip for the detection of anti-Leishmania infantum antibodies. The soluble antigens of L. infantum were securely immobilized on an SPR gold disk by an 11-MUA self-assembled monolayer. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) techniques were employed in the characterization of the antigen immobilization. After the immunosensor construction, canine serum positive for visceral leishmaniasis was added to its surface and showed significant variation in the SPR angle, indicating excellent sensitivity of the technique for antigen-antibody interaction detection. Moreover, the addition of negative serum was accompanied by a smaller response, demonstrating that the immunosensor shows good specificity against anti-L. infantum antibodies. Therefore, this work demonstrates the successful development of an SPR sensor for anti-L. infantum antibodies detection in short time, showing a great perspective as a sensing system of visceral leishmaniasis in endemic regions. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Surface plasmon resonance immunosensor for bacteria detection.

    PubMed

    Baccar, H; Mejri, M B; Hafaiedh, I; Ktari, T; Aouni, M; Abdelghani, A

    2010-07-15

    This work describes an approach for the development of two bacteria biosensors based on surface plasmon resonance (SPR) technique. The first biosensor was based on functionalized gold substrate and the second one on immobilized gold nanoparticles. For the first biosensor, the gold substrate was functionalized with acid-thiol using the self-assembled monolayer technique, while the second one was functionalized with gold nanoparticles immobilized on modified gold substrate. A polyclonal anti-Escherichia coli antibody was immobilized for specific (E. coli) and non-specific (Lactobacillus) bacteria detection. Detection limit with a good reproducibility of 10(4) and 10(3) cfu mL(-1) of E. coli bacteria has been obtained for the first biosensor and for the second one respectively. A refractive index variation below 5x10(-3) due to bacteria adsorption is able to be detected. The refractive index of the multilayer structure and of the E. coli bacteria layer was estimated with a modeling software.

  14. Comparison of three immunosensor methods (surface plasmon resonance, screen-printed and classical amperometric immunosensors) for immunoglobulin G determination in human serum and animal or powdered milks.

    PubMed

    Tomassetti, Mauro; Martini, Elisabetta; Campanella, Luigi; Favero, Gabriele; Carlucci, Luciano; Mazzei, Franco

    2013-01-25

    Within the framework of research carried out by our team aimed at developing new immunological methods to determine proteins such as immunoglobulins G in different biological matrixes, for instance, serum and milk, tests were performed on several immunosensors based on different transducer types, i.e. amperometric (classical or screen-printed) electrodes for hydrogen peroxide. Lastly the feasibility of constructing immunosensors based on surface plasmon resonance (SPR) was investigated. "Competitive" immunological procedures were used in the first two cases. Conversely, the surface plasmon resonance transduction technique allowed a "direct" measurement. Applications were performed on human serum, powdered milks for babies and particularly on several animal milks, in the case of buffalo milk seeking a routine control method to identify possible inflammatory affections in the animals.

  15. A Flow SPR Immunosensor Based on a Sandwich Direct Method

    PubMed Central

    Tomassetti, Mauro; Conta, Giorgia; Campanella, Luigi; Favero, Gabriele; Sanzò, Gabriella; Mazzei, Franco; Antiochia, Riccarda

    2016-01-01

    In this study, we report the development of an SPR (Surface Plasmon Resonance) immunosensor for the detection of ampicillin, operating under flow conditions. SPR sensors based on both direct (with the immobilization of the antibody) and competitive (with the immobilization of the antigen) methods did not allow the detection of ampicillin. Therefore, a sandwich-based sensor was developed which showed a good linear response towards ampicillin between 10−3 and 10−1 M, a measurement time of ≤20 min and a high selectivity both towards β-lactam antibiotics and antibiotics of different classes. PMID:27187486

  16. The phenomenon of fluorescence in immunosensors.

    PubMed

    Kłos-Witkowska, Aleksandra

    2016-01-01

    The phenomenon of fluorescence in immunosensors is described in this paper. Both structure and characteristics of biosensors and immunosensors are presented. Types of immunosensors and the response of bioreceptor layers to the reaction with analytes as well as measurements of electrochemical, piezoelectric and optical parameters in immunosensors are also presented. In addition, detection techniques used in studies of optical immunosensors based on light-matter interactions (absorbance, reflectance, dispersion, emission) such as: UV/VIS spectroscopy, reflectometric interference spectroscopy (RIfs), surface plasmon resonance (SPR), optical waveguide light-mode spectroscopy (OWLS), fluorescence spectroscopy. The phenomenon of fluorescence in immunosensors and standard configurations of immunoreactions between an antigen and an antibody (direct, competitive, sandwich, displacement) is described. Fluorescence parameters taken into account in analyses and fluorescence detection techniques used in research of immunosensors are presented. Examples of immunosensor applications are given.

  17. Development of a surface plasmon resonance immunosensor for detecting melamine in milk products and pet foods.

    PubMed

    Lu, Yang; Xia, Yinqiang; Pan, Mingfei; Wang, Xiaojun; Wang, Shuo

    2014-12-24

    A sensitive and stable surface plasmon resonance (SPR) immunosensor based on the inhibition format was developed and validated for detecting melamine (MEL) in milk products and pet foods. The sensitivity and the limit of detection (LOD) of the proposed method for MEL were 2.32 × 10(-2) and 1.4 × 10(-3) μg/mL, respectively. The immunosensor was highly specific to MEL, which displayed only low cross-reactivity (CR) (<0.01%) for cyanuric acid, cyanuric chloride, and atrazine. The assay was validated for the detection of MEL in full-cream milk, skim milk powder, infant formula, dog food, and cat food. Most of the recovery results ranged between 76 and 115%. The sensitivities of the assay in each type of sample were 2.57 × 10(-2) μg/mL, 2.32 × 10(-2) μg/kg, 2.51 × 10(-2) μg/kg, 2.66 × 10(-2) μg/kg, and 2.68 × 10(-2) μg/kg, respectively, which were much lower than the maximum residue levels (MRLs) of MEL.

  18. ZnS-nanocrystals/polypyrrole nanocomposite film based immunosensor

    NASA Astrophysics Data System (ADS)

    Mishra, Sujeet K.; Pasricha, Renu; Biradar, Ashok M.; Rajesh

    2012-01-01

    We report an electrochemically synthesized ZnS nanocrystals modified polypyrrole (PPy) nanocomposite film based immunosensor for the detection of C-reactive protein (αCRP). The ZnS-PPy composite film was characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM) and electrochemical techniques. The modified film showed good biocompatibility with efficient binding to protein antibody (αCRP-Ab) molecules through ZnS nanocrystals, exhibited an attractive platform for immunosensor fabrication. The electrical and sensing properties of the polymer composite film of different thickness towards protein antigen (αCRP-Ag) were delineated. The immunosensor exhibited an impedance response to αCRP-Ag concentration in a linear range from 10 ng to 10 μg mL-1.

  19. Impedimetric immunoglobulin G immunosensor based on chemically modified graphenes

    NASA Astrophysics Data System (ADS)

    Loo, Adeline Huiling; Bonanni, Alessandra; Ambrosi, Adriano; Poh, Hwee Ling; Pumera, Martin

    2012-01-01

    Immunosensors which display high sensitivity and selectivity are of utmost importance to the biomedical field. Graphene is a material which has immense potential for the fabrication of immunosensors. For the first time, we evaluate the immunosensing capabilities of various graphene surfaces in this work. We propose a simple and label-free electrochemical impedimetric immunosensor for immunoglobulin G (IgG) based on chemically modified graphene (CMG) surfaces such as graphite oxide, graphene oxide, thermally reduced graphene oxide and electrochemically reduced graphene oxide. Disposable electrochemical printed electrodes were first modified with CMG materials before anti-immunoglobulin G (anti-IgG), which is specific to IgG, was immobilized. The principle of detection lies in the changes in impedance spectra of the redox probe after the attachment of IgG to the immobilized anti-IgG. It was found that thermally reduced graphene oxide has the best performance when compared to the other CMG materials. In addition, the optimal concentration of anti-IgG to be deposited onto the modified electrode surface is 10 μg ml-1 and the linear range of detection of the immunosensor is from 0.3 μg ml-1 to 7 μg ml-1. Finally, the fabricated immunosensor also displays selectivity for IgG.Immunosensors which display high sensitivity and selectivity are of utmost importance to the biomedical field. Graphene is a material which has immense potential for the fabrication of immunosensors. For the first time, we evaluate the immunosensing capabilities of various graphene surfaces in this work. We propose a simple and label-free electrochemical impedimetric immunosensor for immunoglobulin G (IgG) based on chemically modified graphene (CMG) surfaces such as graphite oxide, graphene oxide, thermally reduced graphene oxide and electrochemically reduced graphene oxide. Disposable electrochemical printed electrodes were first modified with CMG materials before anti-immunoglobulin G (anti

  20. Nanomaterials-Based Electrochemical Immunosensors for Proteins

    PubMed Central

    RUSLING, JAMES F.

    2012-01-01

    For this special issue on 90 years of polarography, the following personal account describes how my early research in electrochemistry and polarography in the laboratory of Prof. Petr Zuman led to a major research effort in the determination of proteins for cancer detection and monitoring. It reviews the very recent history of nanoparticle labels and multiplexed detection in protein immunosensors. It then describes our journey of discovery that has led to ultrasensitive protein immunosensors achieved by combining nanostructured electrodes with particles labeled with up to ½ million enzymes that can detect down to as little as 1 fg mL−1 protein in diluted serum. Our most mature multiple protein detection system is a microfluidic device with eight sensors coated with 5-nm gold nanoparticles that uses off-line protein detection with heavily labeled magnetic particles. This approach has led to reliable sub pg mL−1 detection limits for multiple proteins, provides excellent correlation with referee ELISA methods, and is currently being used for validation of panels of biomarkers for oral and prostate cancer. The article ends with a section on future perspectives. PMID:22287094

  1. Immunosensor array platforms based on self-assembled dithiols for the electrochemical detection of tetrodotoxins in puffer fish.

    PubMed

    Reverté, Laia; Campbell, Katrina; Rambla-Alegre, Maria; Elliott, Christopher T; Diogène, Jorge; Campàs, Mònica

    2017-10-09

    The recent detection of tetrodotoxins (TTXs) in European fish and shellfish has emphasized the urgent need to develop specific, selective, rapid and easy-to-use methods for their detection to assess the potential risk posed to human health. For this purpose, a dithiol self-assembled monolayer (SAM)-based immunoassay previously performed on maleimide plates (mELISA) has been adapted to gold electrode arrays for the development of an electrochemical immunosensor for TTX. The electrochemical SAM-based immunosensor designed herein, provided an oriented, stable and spaced sensing platform for the determination of TTX, attaining a limit of detection of 2.6 ng mL(-1). The applicability of the biosensor array was demonstrated by the accurate quantifications obtained in the analysis of different tissues of several puffer fish species (Lagocephalus lagocephalus, L. sceleratus and Sphoeroides pachygaster) caught along the Mediterranean coast of Spain. The good agreements found between the TTX concentrations determined by the immunosensor array platforms and those determined by mELISA, surface Plasmon resonance (SPR) immunosensor and liquid chromatography-high resolution mass spectrometry (LC-HRMS) analysis, proved the feasibility of the approach. The electrochemical immunosensor enables the determination of TTXs at levels as low as 0.07 mg TTX equiv. kg(-1) tissue, thus, well below the Japanese value of 2 mg TTX equiv. kg(-1) tissue used as a criterion to consider puffer fish safe for consumption. Compared to the colorimetric SAM-based approach, the immunosensor array described herein shows promise towards the development of disposable, portable and compact analysis tools applicable in monitoring programs for the surveillance of fishery products. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Nanomaterial-Based Electrochemical Immunosensors for Clinically Significant Biomarkers

    PubMed Central

    Ronkainen, Niina J.; Okon, Stanley L.

    2014-01-01

    Nanotechnology has played a crucial role in the development of biosensors over the past decade. The development, testing, optimization, and validation of new biosensors has become a highly interdisciplinary effort involving experts in chemistry, biology, physics, engineering, and medicine. The sensitivity, the specificity and the reproducibility of biosensors have improved tremendously as a result of incorporating nanomaterials in their design. In general, nanomaterials-based electrochemical immunosensors amplify the sensitivity by facilitating greater loading of the larger sensing surface with biorecognition molecules as well as improving the electrochemical properties of the transducer. The most common types of nanomaterials and their properties will be described. In addition, the utilization of nanomaterials in immunosensors for biomarker detection will be discussed since these biosensors have enormous potential for a myriad of clinical uses. Electrochemical immunosensors provide a specific and simple analytical alternative as evidenced by their brief analysis times, inexpensive instrumentation, lower assay cost as well as good portability and amenability to miniaturization. The role nanomaterials play in biosensors, their ability to improve detection capabilities in low concentration analytes yielding clinically useful data and their impact on other biosensor performance properties will be discussed. Finally, the most common types of electroanalytical detection methods will be briefly touched upon. PMID:28788700

  3. Interferometer immunosensor based on porous silicon for determining alpha-fetoprotein

    NASA Astrophysics Data System (ADS)

    Lv, Xiaoyi; Jiang, Jing; Lv, Guodong; Mo, Jiaqing; Jia, Zhenhong

    2016-10-01

    An increased level of alpha-fetoprotein ( AFP) in the blood may be a sign of liver cancer. Porous silicon based optical microcavities structure is prepared as a label-free immunosensor platform for detecting AFP. After the antigen-antibody reaction, it is monitored that the red shift of the reflection spectrum of the immunosensor increases

  4. Surface plasmon resonance immunosensor for the detection of Salmonella typhi antibodies in buffer and patient serum.

    PubMed

    Gupta, Garima; Sharma, P K; Sikarwar, B; Merwyn, S; Kaushik, S; Boopathi, M; Agarwal, G S; Singh, Beer

    2012-01-01

    Surface plasmon resonance (SPR) immunosensor using 4-mercaptobenzoic acid (4-MBA) modified gold SPR chip was developed first time for the detection of flagellin specific antibodies of Salmonella typhi (S. typhi). Flagellin protein of S. typhi was prepared by recombinant DNA technology. The modification of gold chip with 4-MBA was in-situ characterized by SPR and electrochemical impedance spectroscopy. By using kinetic evaluation software, K(D) and B(max) values were calculated and found to be 26.3 fM and 62.04 m°, respectively, for the immobilized monoclonal antibody (Moab) of recombinant flagellin (r-fla) protein of S. typhi (r-fla S. typhi). In addition, thermodynamic parameters such as ΔG, ΔH and ΔS were determined first time for r-fla S. typhi and Moab of r-fla S. typhi interactions and the values revealed the interaction between r-fla S. typhi and Moab of r-fla S. typhi as spontaneous, endothermic and entropy driven one. Moreover, healthy human serum samples and patient sera (Widal positive and Widal negative) were subjected to SPR analysis. The present SPR based approach provides an alternative way for S. typhi detection in less than 10 min.

  5. Impedimetric characterization of adsorption of Listeria monocytogenes on the surface of an aluminum-based immunosensor.

    PubMed

    Chai, Changhoon; Lee, Jooyoung; Oh, Se-Wook; Takhistov, Paul

    2014-11-01

    The impedimetric characteristics of an immunosensor depend on the electrical properties of an immunosensor substrate. The impedimetric characteristics of an immunosensor compared with adsorption of Listeria monocytogenes were investigated on an aluminum surface insulated with an electrically resistive aluminum oxide layer. Antibody for L. monocytogenes (anti-L. monocytogenes) was immobilized on an aluminum surface that was insulated with a native air-formed aluminum oxide layer. The resistance of impedance (R) value of an aluminum-based immunosensor decreased, especially at 10(4) to 10(6) Hz, where the effect of the reactance of impedance (X) was minimal when L. monocytogenes was adsorbed on the immunosensor surface. The R value of the immunosensor at 81 kHz decreased proportionally to the concentration of L. monocytogenes from 1.3 to 4.3 log CFU mL(-1) . The adsorption of L. monocytogenes produced local protrusions on the immunosensor surface, causing physicochemical changes in the ionic layer formed on the immunosensor surface by a sinusoidal electrical signal input, which might help electrical current to flow and cause the R value to decrease. © 2014 Institute of Food Technologists®

  6. Smartphone-based immunosensor for CA125 detection.

    PubMed

    Hosu, Oana; Ravalli, Andrea; Lo Piccolo, Giuseppe Mattia; Cristea, Cecilia; Sandulescu, Robert; Marrazza, Giovanna

    2017-05-01

    In this work, we report the design, the development and the characterization of the analytical performances of a colorimetric smartphone-based immunosensor for the detection of cancer antigen 125 (CA125). The immunosensor was based on a sandwich strategy in which the primary antibody was immobilized by spotting onto the 3D nitrocellulose membrane. The immunospots were subsequently incubated with CA125 solutions, followed by the affinity reaction with a secondary antibody labeled with gold nanoparticles (AuNPs). The antibody-AuNPs captured onto immunospots induced the silver deposition from a silver enhancer solution leading to the formation of gold-silver nanoparticles of different grey color spots depending on CA125 concentration. The 8 megapixels smartphone camera was integrated in a home-made dark box and used as transducer of color image acquisition and data handling. The pixel intensity of the captured images was determined by an image processing algorithm. The experimental parameters involved in each step of the immunosensor design were studied and optimized, obtaining a limit of detection of 30U/mL CA125. The selectivity of the immunoassay was proven against different concentration solutions of Vascular Endothelial Growth Factor (VEGF) antigen as an unspecific protein when a blank signal was obtained for all tested solutions. Finally, preliminary experiments in human serum samples spiked with CA125 protein were also performed. Therefore, the proposed system could represent a powerful point-of-care tool for the next generation technology for detecting and monitoring cancer biomarkers at early stages by taking advantage of nowadays gadgets with enhanced features such as smartphones.

  7. A Renewable Electrochemical Magnetic Immunosensor Based on Gold Nanoparticle Labels

    SciTech Connect

    Liu, Guodong; Lin, Yuehe

    2005-05-24

    A particle-based renewable electrochemical magnetic immunosensor was developed by using magnetic beads and a gold nanoparticle label. Anti-IgG antibody-modified magnetic beads were attached to a renewable carbon paste transducer surface by magnets that were fixed inside the sensor. A gold nanoparticle label was capsulated to the surface of magnetic beads by sandwich immunoassay. Highly sensitive electrochemical stripping analysis offers a simple and fast method to quantify the capatured gold nanoparticle tracer and avoid the use of an enzyme label and substrate. The stripping signal of gold nanoparticle is related to the concentration of target IgG in the sample solution. A transmission electron microscopy image shows that the gold nanoparticles were successfully capsulated to the surface of magnetic beads through sandwich immunoreaction events. The parameters of immunoassay, including the loading of magnetic beads, the amount of gold nanoparticle conjugate, and the immunoreaction time, were optimized. The detection limit of 0.02 μg ml-1of IgG was obtained under optimum experimental conditions. Such particle-based electrochemical magnetic immunosensors could be readily used for simultaneous parallel detection of multiple proteins by using multiple inorganic metal nanoparticle tracers and are expected to open new opportunities for disease diagnostics and biosecurity.

  8. A renewable electrochemical magnetic immunosensor based on gold nanoparticle labels.

    PubMed

    Liu, Guodong; Lin, Yuehe

    2005-07-01

    A particle-based renewable electrochemical magnetic immunosensor was developed by using magnetic beads and gold nanoparticle labels. Anti-IgG antibody-modified magnetic beads were attached to a renewable carbon paste transducer surface by magnet that was fixed inside the sensor. Gold nanoparticle labels were capsulated to the surface of magnetic beads by sandwich immunoassay. Highly sensitive electrochemical stripping analysis offers a simple and fast method to quantify the capatured gold nanoparticle tracers and avoid the use of an enzyme label and substrate. The stripping signal of gold nanoparticles is related to the concentration of target IgG in the sample solution. A transmission electron microscopy image shows that the gold nanoparticles were successfully capsulated to the surface of magnetic beads through sandwich immunoreaction events. The parameters of immunoassay, including the loading of magnetic beads, the amount of gold nanoparticle conjugate, and the immunoreaction time, were optimized. The detection limit of 0.02 microg ml(-1) of IgG was obtained under optimum experimental conditions. Such particle-based electrochemical magnetic immunosensors could be readily used for simultaneous parallel detection of multiple proteins by using multiple inorganic metal nanoparticle tracers and are expected to open new opportunities for disease diagnostics and biosecurity.

  9. Ratiometric ultrasensitive electrochemical immunosensor based on redox substrate and immunoprobe

    NASA Astrophysics Data System (ADS)

    Tang, Zhongxue; Ma, Zhanfang

    2016-10-01

    In this work, we presented a ratiometric electrochemical immunosensor based on redox substrate and immunoprobe. Carboxymethyl cellulose-Au-Pb2+ (CMC-Au-Pb2+) and carbon-Au-Cu2+ (C-Au-Cu2+) nanocomposites were firstly synthesized and implemented as redox substrate and immunoprobe with strong current signals at ‑0.45 V and 0.15 V, respectively. Human immunoglobulin G (IgG) was used as a model analyte to examine the analytical performance of the proposed method. The current signals of CMC-Au-Pb2+ (Isubstrate) and C-Au-Cu2+ (Iprobe) were monitored. The effect of redox substrate and immunoprobe behaved as a better linear relationship between Iprobe/Isubstrate and Lg CIgG (ng mL‑1). By measuring the signal ratio Iprobe/Isubstrate, the sandwich immunosensor for IgG exhibited a wide linear range from 1 fg mL‑1 to 100 ng mL‑1, which was two orders of magnitude higher than other previous works. The limit of detection reached 0.26 fg mL‑1. Furthermore, for human serum samples, the results from this method were consistent with those of the enzyme linked immunosorbent assay (ELISA), demonstrating that the proposed immunoassay was of great potential in clinical diagnosis.

  10. Ratiometric ultrasensitive electrochemical immunosensor based on redox substrate and immunoprobe

    PubMed Central

    Tang, Zhongxue; Ma, Zhanfang

    2016-01-01

    In this work, we presented a ratiometric electrochemical immunosensor based on redox substrate and immunoprobe. Carboxymethyl cellulose-Au-Pb2+ (CMC-Au-Pb2+) and carbon-Au-Cu2+ (C-Au-Cu2+) nanocomposites were firstly synthesized and implemented as redox substrate and immunoprobe with strong current signals at −0.45 V and 0.15 V, respectively. Human immunoglobulin G (IgG) was used as a model analyte to examine the analytical performance of the proposed method. The current signals of CMC-Au-Pb2+ (Isubstrate) and C-Au-Cu2+ (Iprobe) were monitored. The effect of redox substrate and immunoprobe behaved as a better linear relationship between Iprobe/Isubstrate and Lg CIgG (ng mL−1). By measuring the signal ratio Iprobe/Isubstrate, the sandwich immunosensor for IgG exhibited a wide linear range from 1 fg mL−1 to 100 ng mL−1, which was two orders of magnitude higher than other previous works. The limit of detection reached 0.26 fg mL−1. Furthermore, for human serum samples, the results from this method were consistent with those of the enzyme linked immunosorbent assay (ELISA), demonstrating that the proposed immunoassay was of great potential in clinical diagnosis. PMID:27739493

  11. An electrochemical immunosensor based on pristine graphene for rapid determination of ractopamine

    NASA Astrophysics Data System (ADS)

    Qi, Shaopeng; Zhao, Bo; Zhou, Bo; Jiang, Xiaoqing

    2017-10-01

    A new electrochemical immunosensor for fast determination of ractopamine (RAC) is fabricated based on pristine graphene (PG). The PG provides a microenvironment beneficial the immobilization of RAC, promotes the electron transfer, and raises the sensitivity of the immunosensor. The free RAC in solution can be effectively measured based on the competitive immunoreaction between RAC-antibody and RAC. The calibration graph shows linearity over the concentration ranges of 0.1-10 and 10-4000 ng mL-1. The proposed immunosensor displays a satisfactory stability, selectivity, and reproducibility and has been applied to the quantificational detection of RAC in real pork samples.

  12. A gold nanoparticles enhanced surface plasmon resonance immunosensor for highly sensitive detection of ischemia-modified albumin.

    PubMed

    Li, Guang; Li, Xian; Yang, Meng; Chen, Meng-Meng; Chen, Long-Cong; Xiong, Xing-Liang

    2013-09-25

    In this study a novel sensitive nanogold particle sensor enhancement based on mixed self-assembled monolayers was explored and used to construct a Surface Plasmon Resonance (SPR) immunosensor to detect Ischemia Modified Albumin (IMA). Compared with a direct binding SPR assay at a limit of detection (LOD) of 100 ng/L, gold nanoparticles (AuNPs) of 10 nm dramatically improved the LOD of IMA to 10 ng/L. Meanwhile, no interfering substance that may lead to false positive results was identified. These results suggested that the SPR biosensor presented superior properties, and provided a simple label-free strategy to increase assay sensitivity for further acute coronary syndrome (ACS) diagnosis.

  13. Surface plasmon resonance aided electrochemical immunosensor for CK-MB determination in undiluted serum samples

    PubMed Central

    Garay, Fernando; Kisiel, Greggory; Fang, Aiping; Lindner, Ernő

    2010-01-01

    This article presents a simple chronoamperometric immunosensor for the quantitative assessment of creatine kinase MB (CK-MB) in 50 µL undiluted serum samples. The immunosensor consists of gold working and counter electrodes patterned onto a glass chip by thin-film photolithography and an external Ag|AgCl reference electrode. The detection limit (DL) of the chronoamperometric method is 13 ng mL−1 (DL = 2×RMSD/S, where RMSD is the residual mean standard deviation of the measured points around a calibration curve with a slope of S). In spiked serum samples, the response was linear up to 300 ng mL−1 of CK-MB. A surface plasmon resonance (SPR) system with simultaneous electrochemical detection (EC-SPR) aided the development of the sandwich immunoassay. Real-time monitoring of the SPR signal was used to optimize the capture antibody immobilization, CK-MB and detection antibody binding, as well as to minimize the nonspecific adsorption of serum proteins to the sensor surface. The detection antibody has been labeled with alkaline phosphatase (ALP) enzyme for sensitive electrochemical detection. ALP catalyzes the hydrolysis of ascorbic acid phosphate and generates ascorbic acid, which is measured chronoamperometrically. The electrochemical immunoassay for CK-MB was less sensitive to nonspecific adsorption related interferences, had a better detection limit, and required a lower volume of sample than the SPR method. PMID:20449577

  14. A stable and sensitive voltammetric immunosensor based on a new non-enzymatic label.

    PubMed

    Akter, Rashida; Kyun Rhee, Choong; Rahman, Md Aminur

    2013-12-15

    A stable and sensitive electrochemical carcinoembryonic antigen immunosensor based on a new non-enzymatic label (3, 3', 5, 5'-tetramethylbenzidine (TMB)) was fabricated using gold nanoparticles-deposited polydopamine film (PD/AuNPs) as an anti-CEA antibody immobilizing platform. TMB was conjugated with CEA and utilized as an electrochemical label. The PD/AuNPs platform provides enhanced conductivity, thus the redox reaction of TMB label was observed at the immunosensor probe. The immunosensor probe was characterized using scanning electron microscopy and electrochemical impedance spectroscopy. The CEA detection was based on the competitive binding of free- and TMB-conjugated-CEA to the anti-CEA antibody. Using differential pulse voltammetry, CEA can be selectively detected as low as 10±0.6 pg/mL. The present immunosensor method was applied to CEA-spiked human serum samples and the recovery results were satisfactory. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Scalable fabrication of immunosensors based on carbon nanotube polymer composites.

    PubMed

    Mendoza, Ernest; Orozco, Jahir; Jiménez-Jorquera, Cecilia; González-Guerrero, Ana B; Calle, Ana; Lechuga, Laura M; Fernández-Sánchez, César

    2008-02-20

    In this work we present the fabrication and characterization of immunosensors based on polystyrene (PS)-multiwalled carbon nanotube (MWCNT) composites. The electrochemical properties of the sensors have been investigated and show that the surface area is increased upon addition of the MWCNT-PS layer. Furthermore, a plasma activation process is used to partially remove the PS and expose the MWCNTs. This results in a huge increase in the electrochemical area and opens up the possibility of binding biomolecules to the MWCNT wall. The MWCNTs have been functionalized covalently with a model antibody (rabbit IgG). The biosensors have been tested using amperometric techniques and show detection limits comparable to standard techniques such as ELISA.

  16. Ultrasensitive electrochemiluminescence immunosensor based on luminol functionalized gold nanoparticle labeling.

    PubMed

    Tian, Dayong; Duan, Chunfeng; Wang, Wei; Cui, Hua

    2010-06-15

    An ultrasensitive electrochemiluminescence (ECL) immunosensor based on luminol functionalized gold nanoparticle (AuNP) labeling was developed using human immunoglobulin G (hIgG) as a model analyte. The primary antibody biotin-conjugated goat-anti-human IgG was first immobilized on a streptavidin coated AuNP modified electrode, then the antigen (human IgG) and the luminol functionalized AuNP-labeled second antibody were conjugated successively to form a sandwich-type immunocomplex, i.e. immunosensor. ECL was carried out with a double-step potential in carbonate buffer solution containing 1.0 mmol/L H(2)O(2). Since thousand of luminol molecules were coated on the surface of AuNPs to realize labeling of multiple molecules with CL activity at a single antibody and the amplification of AuNPs and biotin-streptavidin system was utilized, luminol ECL signal could be enhanced greatly, finally resulting in extremely high sensitivity. The ECL method shows a detection limit of 1.0 pg/mL (S/N=3) for hIgG, which is superior to all previously reported methods for the determination of hIgG. Moreover, the proposed method is also simple, stable, specific, and time-saving, avoiding the complicated stripping procedure during CL detection and the uncontrollable synthesis of irregular nanoparticles compared with other chemiluminescence immunoassay based on AuNP labeling. Additionally, the labeling procedure is also superior to that of other reported multilabeling strategies, such as Ru complex-encapsulated polymer microspheres, and most of Ru complex-encapsulated liposomes in simplicity, stability, labeling property and practical applicability. Finally, the proposed method has been successfully applied to the detection of hIgG in human serums.

  17. Sensitive electrochemical immunosensor based on three-dimensional nanostructure gold electrode.

    PubMed

    Zhong, Guangxian; Lan, Ruilong; Zhang, Wenxin; Fu, Feihuan; Sun, Yiming; Peng, Huaping; Chen, Tianbin; Cai, Yishan; Liu, Ailin; Lin, Jianhua; Lin, Xinhua

    2015-01-01

    A sensitive electrochemical immunosensor was developed for detection of alpha-fetoprotein (AFP) based on a three-dimensional nanostructure gold electrode using a facile, rapid, "green" square-wave oxidation-reduction cycle technique. The resulting three-dimensional gold nanocomposites were characterized by scanning electron microscopy and cyclic voltammetry. A "sandwich-type" detection strategy using an electrochemical immunosensor was employed. Under optimal conditions, a good linear relationship between the current response signal and the AFP concentrations was observed in the range of 10-50 ng/mL with a detection limit of 3 pg/mL. This new immunosensor showed a fast amperometric response and high sensitivity and selectivity. It was successfully used to determine AFP in a human serum sample with a relative standard deviation of <5% (n=5). The proposed immunosensor represents a significant step toward practical application in clinical diagnosis and monitoring of prognosis.

  18. SPR based immunosensor for detection of Legionella pneumophila in water samples

    NASA Astrophysics Data System (ADS)

    Enrico, De Lorenzis; Manera, Maria G.; Montagna, Giovanni; Cimaglia, Fabio; Chiesa, Maurizio; Poltronieri, Palmiro; Santino, Angelo; Rella, Roberto

    2013-05-01

    Detection of legionellae by water sampling is an important factor in epidemiological investigations of Legionnaires' disease and its prevention. To avoid labor-intensive problems with conventional methods, an alternative, highly sensitive and simple method is proposed for detecting L. pneumophila in aqueous samples. A compact Surface Plasmon Resonance (SPR) instrumentation prototype, provided with proper microfluidics tools, is built. The developed immunosensor is capable of dynamically following the binding between antigens and the corresponding antibody molecules immobilized on the SPR sensor surface. A proper immobilization strategy is used in this work that makes use of an important efficient step aimed at the orientation of antibodies onto the sensor surface. The feasibility of the integration of SPR-based biosensing setups with microfluidic technologies, resulting in a low-cost and portable biosensor is demonstrated.

  19. Fabrication of a label-free plasmon immunosensor based on triangular silver nanoplates

    NASA Astrophysics Data System (ADS)

    Dong, Peipei; Lin, Yuanyuan; Di, Junwei

    2013-08-01

    In this work, we have firstly electrodeposited small gold seeds (average diameter of ~40 nm) onto transparent indium tin oxide (ITO) thin film coated glass. Then silver triangular nanoplates with edge lengths of ~200 nm were fabricated using seed-mediated growth method. The localized surface plasmon resonance (LSPR) peak was located at ~700 nm. Finally, a label-free plasmon immunosensor was prepared by directly immobilizing goat anti-mouse IgG onto silver surface. The performance of the LSPR immunosensor was investigated. The red-shift of the biosensor was linearly proportional to mouse IgG concentration ranged from 5 ng/mL to 500 ng/mL, with a detection limit of 2 ng/mL. The label-free immunosensor was simple, sensitive and selective.

  20. A photoelectrochemical immunosensor for detection of α-fetoprotein based on Au-ZnO flower-rod heterostructures

    NASA Astrophysics Data System (ADS)

    Han, Zhizhong; Luo, Min; Chen, Li; Chen, Jinghua; Li, Chunyan

    2017-04-01

    In this work, a novel label free photoelectrochemical (PEC) immunosensor has been developed for the detection of α-fetoprotein (AFP). The immunosensor was based on Au-ZnO flower-rods (FRs) heterostructure, where Au nanoparticles (NPs) were firstly electrodeposited by cyclic voltammetry methods. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Mott-Schottky plot (MS), UV-vis diffuse reflectance spectrum and fluorescence emission spectrum were used for the characterizations of Au-ZnO FRs. The results demonstrated that Au NPs not only obviously enhanced the visible light absorption of ZnO FRs due to surface plasmon resonance (SPR) but also improved the separation of photo-generated electron-hole pairs. Therefore, the photocurrent of Au-ZnO FRs was increased under simulated sunlight. The photocurrent was reduced after the specific antibody-antigen immune reaction. And the photocurrent decrement was linear with the logarithm of AFP antigen concentration in the range from 0.005 ng mL-1 to 50 ng mL-1 with a low detection limit of 0.56 pg mL-1 (S/N = 3). The PEC immunosensor also exhibited high anti-interference property and acceptable stability. This work would provide a promising photoelectrochemical strategy for the detection of other proteins in clinical diagnosis.

  1. Development of an Immunosensor Based on Layered Double Hydroxides for MMR Cancer Biomarker Detection.

    PubMed

    Hammami, M; Soussou, A; Idoudi, F; Cohen-Bouhacina, T; Bouhaouala-Zahar, B; Baccar, Z M

    2015-10-01

    As a potential biomarker for the investigation of cancer inflammatory profiles, macrophage mannose receptor (MMR, CD206) is herein selected to develop an immunosensor based on layered double hydroxide (LDH). Like an endocyte C-type lectin receptor, MMR plays an important role in immune homeostasis by scavenging unwanted mannose glycoproteins. It attracts a progressive attention thanks to its particularly high expression within the tumor microenvironment. There is a great of interest to develop an immunosensor based on an antibody specific to MMR for detection of stroma versus tumor cells. In this work, we studied the feasibility of high sensitive MMR cancer Screen Printed Electrode (SPE) immunosensor. Working electrode of commercialized SPE was modified by immobilization of specific antibody (anti-MMR) into thin layer of LDH nanomaterials. Structural, morphological, and surface properties of LDHs were studied by X-Ray diffraction, atomic force microscopy and Infrared spectroscopy in ATR. Cyclic Voltammetry technique was used to study interaction between the human recombinant MMR protein (rHu-MMR, NSO derived) and an immobilized antibody into developed immunosensor. High specific response of -11.72 μA/ng.mL(-1) (with a correlation coefficient of R(2)=0.994 ) were obtained in linear range of 0.05 ng/mL to 10.0 ng/mL of specific recombinant antigen. The limit of detection (LOD) was less than 15.0 pg/mL. From these attractive results, the feasibility of an electrochemical immunosensor for cancer was proved. Additional experiments to study stability and reproducibility the immunosensor should be completed in perspective to use these anti-MMR based immunosensors for sensing human MMR in patient biopsies and sera.

  2. Label-free bead-based metallothionein electrochemical immunosensor.

    PubMed

    Nejdl, Lukas; Nguyen, Hoai Viet; Richtera, Lukas; Krizkova, Sona; Guran, Roman; Masarik, Michal; Hynek, David; Heger, Zbynek; Lundberg, Karin; Erikson, Kristofer; Adam, Vojtech; Kizek, Rene

    2015-08-01

    A novel microfluidic label-free bead-based metallothionein immunosensors was designed. To the surface of superparamagnetic agarose beads coated with protein A, polyclonal chicken IgY specifically recognizing metallothionein (MT) were immobilized via rabbit IgG. The Brdicka reaction was used for metallothionein detection in a microfluidic printed 3D chip. The assembled chip consisted of a single copper wire coated with a thin layer of amalgam as working electrode. Optimization of MT detection using designed microfluidic chip was performed in stationary system as well as in the flow arrangement at various flow rates (0-1800 μL/min). In stationary arrangement it is possible to detect MT concentrations up to 30 ng/mL level, flow arrangement allows reliable detection of even lower concentration (12.5 ng/mL). The assembled miniature flow chip was subsequently tested for the detection of MT elevated levels (at approx. level 100 μg/mL) in samples of patients with cancer. The stability of constructed device for metallothionein detection in flow arrangement was found to be several days without any maintenance needed.

  3. Highly sensitive microcantilever-based immunosensor for the detection of carbofuran in soil and vegetable samples.

    PubMed

    Dai, Yingping; Wang, Ting; Hu, Xiaoya; Liu, Shuzhao; Zhang, Ming; Wang, Chengyin

    2017-08-15

    Microcantilever-based immunosensor is a next-generation electromechanical technique with broad application in biological detection. In this paper, we reported a microcantilever-based immunosensor that quantitatively detect the carbofuran, by using monoclonal antibodies to carbofuran as the receptor molecules. The surface of gold-coated microcantilever was chemically modified by the crosslinking of l-cysteine (l-cys)/glutaraldehyde (GA). The monoclonal antibodies to carbofuran were then immobilized on the side of the microcantilever to fabricate the immunosensor, the mechanical bending induced by antigen-antibody specific binding under an experimental environment. Under the optimized conditions, immunosensor detected carbofuran showed a good linear relationship over the range from 1.0×10(-7) to 1.0×10(-3)g/L (R=0.998), with a detection limit of 0.1ng/mL. Moreover, the proposed immunosensor exhibited high sensitivity, specificity and good stability and can be successfully applied in the carbofuran determination in soil and vegetable samples with satisfactory results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Single-domain antibody based thermally stable electrochemical immunosensor.

    PubMed

    Singh, Aparajita; Pasha, Syed Khalid; Manickam, Pandiaraj; Bhansali, Shekhar

    2016-09-15

    Conventional monoclonal and polyclonal antibodies are sensitive to changes in environmental factors such as temperature, pH, humidity, etc. This limits the current cost-effective and portable electrochemical immunosensors in harsh environments. Using Ricin Chain-A, a naturally occurring toxin, as a model analyte we report fabrication of a thermally stable electrochemical immunosensor. Single-domain antibodies (sdAb) or nanobodies have been employed as recognition elements for direct detection of Ricin at temperatures great than 4°C. Immunosensor fabricated using the conventional Ricin monoclonal and polyclonal antibodies have also been demonstrated for comparison. In the case of sdAb immunosensor, Ricin was detected in a linear range of 1log(fg/mL)-1log(μg/mL) with a sensitivity of 0.07μA/log(g/mL)/cm(2) using cyclic voltammetry. The fabricated miniaturized sensors have demonstrated higher shelf life and stability at temperatures up to 40°C. Therefore these electrochemical sensors can be integrated as a part of a portable device for point-of-care immunosensing. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Investigate electrochemical immunosensor of cortisol based on gold nanoparticles/magnetic functionalized reduced graphene oxide.

    PubMed

    Sun, Bolu; Gou, Yuqiang; Ma, Yuling; Zheng, Xiaoping; Bai, Ruibin; Ahmed Abdelmoaty, Ahmed Attia; Hu, Fangdi

    2017-02-15

    A sensitively competitive electrochemical immunosensor for the detection of cortisol was successfully developed based on gold nanoparticles and magnetic functionalized reduced graphene oxide (AuNPs/MrGO). In order to construct the base of the immunosensor, the MrGO was initially fabricated by chemical cross-linking and used to modify the nafion pretreated glassy carbon electrode. Subsequently, the surface of electrode was modified by AuNPs via electrochemical deposition. A variety of cortisol (Cor) can be firmly loaded in the AuNPs/MrGO with large specific surface area and good bioactivity to construct the basic electrode (Cor/AuNPs/MrGO/Nafion@GCE), which was characterized by the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. Due to the cortisol on the surface of basic electrode and samples can competitively combine with the cortisol antibody labelled by horseradish peroxidase (HRP-Strept-Biotin-Ab). Finally, the detection signal of electrochemical immunosensor (HRP-Strept-Biotin-Ab-Cor/AuNPs/MrGO/Nafion@GCE) in the test liquid had negative correlations with the concentration of cortisol in samples. The AuNPs/MrGO with excellent electrical conductivity being applied, the electrochemical response of the immunosensor was immensely amplified. The immunosensor displayed excellent analytical performance for the detection of cortisol range from 0.1 to 1000ng/mL with a detection limit of 0.05ng/mL at 3σ. Moreover, compared the developed immunoassay with commercially available enzyme linked immunosorbent assay, the proposed method showed good precision, acceptable stability and reproducibility, indicating the immunosensor could be used for the sensitive, efficient and real-time detection of cortisol in real samples. Therefore, the present strategy provides a novel and convenient method for clinical determination of cortisol. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    PubMed

    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.

  7. A non-competitive surface plasmon resonance immunosensor for rapid detection of triazophos residue in environmental and agricultural samples.

    PubMed

    Guo, Yirong; Liu, Rui; Liu, Ying; Xiang, Dandan; Liu, Yihua; Gui, Wenjun; Li, Mingyu; Zhu, Guonian

    2017-09-21

    The wide application of an organophosphate pesticide triazophos raises concern on the environmental pollution and the potential risk to human health. Thus, it is crucial to regularly monitor triazophos residue in the environment and agro-products. Herein we described a non-competitive immunoassay for trace detection of triazophos using a direct surface plasmon resonance (SPR) biosensor. Two anti-triazophos monoclonal antibodies (mAbs) were immobilized on the sensor chip and characterized by SPR-based kinetic analysis. The mAb with relatively slow dissociation rate was used for direct immunosensing of triazophos. The biosensor assay showed a high specificity and a low detection limit of 0.096ngmL(-1) to triazophos, with the linear detection range of 0.98-8.29ngmL(-1). Under the optimal condition, the sensor chip could be regenerated for 160cycles at least. Moreover, the sensitive method was applied to determine triazophos in the spiked environmental water and agricultural products, as well as in unknown real-life samples (including Chinese cabbage, cucumber, and apple). Desirable results demonstrated that the newly-developed immunosensor could be used as a rapid, convenient, and reliable tool to regularly monitor triazophos and meet the detection requirement of its maximum residue limits. Copyright © 2017. Published by Elsevier B.V.

  8. Photonic crystal fiber-based immunosensor for high-performance detection of alpha fetoprotein.

    PubMed

    Liu, Xiaoxia; Song, Xingda; Dong, Zhiyong; Meng, Xiaoting; Chen, Yiping; Yang, Li

    2017-05-15

    We have developed a sensitive photonic crystal fiber (PCF)-based immunosensor for detection of alpha fetoprotein (AFP). The unique PCF possesses a morphology characterized by numerous pore structures and a large surface area-to-volume ratio, which can be used as an immune-reaction carrier to improve the sensitivity and reaction speed of AFP detection. The PCF-based immunosensor possesses a low limit of detection of 0.1ng/mL, which is five times lower than that of the capillary-based sensor and 35 times lower than that of the traditional enzyme-linked immunosorbent assay. The wide linear dynamic range of 0.1-150ng/mL makes the developed immunosensor suitable for clinical practice. The proposed method was successfully applied to AFP detection in a clinical serum sample with acceptable precision. It is indicated that the present PCF-based immunosensor could be used as an attractive analytical platform for sensitive and specific detection of cancer biomarkers.

  9. Development of an immunosensor for quantifying zebrafish vitellogenin based on the Octet system.

    PubMed

    Wang, Jun; Wang, Jun; Zhang, Zhenzhong; Zhang, Xiaona; Ru, Shaoguo; Dong, YiFei

    2017-09-15

    Vitellogenin (Vtg) is a sensitive biomarker for environmental estrogens. In this study, an immunosensor for quantifying zebrafish Vtg was developed using the Octet system. First, Protein A sensors were immobilized with purified anti-lipovitellin (Lv) antibody that demonstrated specificity to Vtg. Then, antibody-coated biosensors were immersed into zebrafish Lv standards and diluted samples. The Octet system measured and recorded kinetic parameters between antigens and captured antibody within 5 min. Sample Vtg concentrations were automatically calculated by interpolating relative binding rates observed with each sample and the immobilized anti-Lv antibody into the developed standard curve. The sensor arrays exhibited a wide linear range from 78 to 5000 ng/mL, and the inter-assay coefficient of variation was 0.66-1.97%. Furthermore, the performance of the immunosensor in detecting Vtg was evaluated by quantifying Vtg induction in juvenile zebrafish exposed to 17β-estradiol (E2). Compared with conventional immunoassay techniques, the Vtg immunosensor developed based on the Octet system was much simpler and less time-consuming, allowing rapid Vtg quantification within 15 min. Moreover, Protein A sensors could be reused many times to ensure that the assays have high reproducibility. Therefore, we suggest that immunosensors based on the Octet system are an easily operated detection method for ecotoxicological research. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Label-free C-reactive protein electronic detection with an electrolyte-gated organic field-effect transistor-based immunosensor.

    PubMed

    Magliulo, Maria; De Tullio, Donato; Vikholm-Lundin, Inger; Albers, Willem M; Munter, Tony; Manoli, Kyriaki; Palazzo, Gerardo; Torsi, Luisa

    2016-06-01

    In this contribution, we propose a label-free immunosensor, based on a novel type of electrolyte-gated field-effect transistor (EGOFET), for ultrasensitive detection of the C-reactive protein (CRP). The recognition layer of the biosensor is fabricated by physical adsorption of the anti-CRP monoclonal antibody onto a poly-3-hexyl thiophene (P3HT) organic semiconductor surface. A supplementary nonionic hydrophilic polymer is used as a blocking agent preventing nonspecific interactions and allowing a better orientation of the antibodies immobilized onto the P3HT surface. The whole biomolecule immobilization procedure does not require any pretreatment of the organic semiconductor surface, and the whole functionalization process is completed in less than 30 min. Surface plasmon resonance (SPR) measurements were performed to assess the amount of biomolecules physisorbed onto the P3HT and to evaluate the CRP binding proprieties of the deposited anti-CRP layer. A partial surface coverage of about 23 % of adsorbed antibody molecules was found to most efficiently sense the CRP. The electrical performance of the EGOFET immunosensor was comparable to that of a bare P3HT EGOFET device, and the obtained CRP calibration curve was linear over six orders of magnitude (from 4 pM to 2 μM). The relative standard deviation of the individual calibration points, measured on immunosensors fabricated on different chips, ranged between 1 and 14 %, and a detection limit of 2 pM (220 ng/L) was established. The novel electronic immunosensor is compatible with low-cost fabrication procedures and was successfully employed for the detection of the CRP biomarker in the clinically relevant matrix serum. Graphical abstract Schematic of the EGOFET immunosensor for CRP detection. The anti-CRP monoclonal antibody layer is physisorbed on the P3HT organic semiconductor and the CRP is directly measured by a label-free electronic EGOFET transducer.

  11. A carbon nanofiber-based label free immunosensor for high sensitive detection of recombinant bovine somatotropin.

    PubMed

    Lim, Syazana Abdullah; Ahmed, Minhaz Uddin

    2015-08-15

    A carbon nanofiber-based label free electrochemical immunosensor for sensitive detection of recombinant bovine somatotropin (rbST) was developed. In this immunosensor design, a mild site-directed antibody immobilization via interaction of boronic acid and oligosaccharide moiety found on Fc region of an antibody was performed to preserve the biological activity of antibody and improve the sensor's sensitivity. Electrochemical characterization of the immunosensor fabrication was carried out by differential pulse voltammetry (DPV) in Fe(CN)6(3-)/Fe(CN)6(4-) probe. A comparison study between different transducer platforms showed carbon nanofiber gave higher current signal response than single-walled carbon nanotube. In this work, calibration curve was obtained from the decrease of DPV peak current of Fe(CN)6(3-)/Fe(CN)6(4-) after immunocomplexed was formed. A linear relationship between DPV current change signal response and rbST concentrations from 1 pg/mL to 10 ng/mL (correlation coefficient of 0.9721) was achieved with detection limit of 1 pg/mL. Our developed immunosensor demonstrated high selectivity in cross-reactivity studies and a good percentage recovery in spiked bovine serum sample. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. A fumonisins immunosensor based on polyanilino-carbon nanotubes doped with palladium telluride quantum dots.

    PubMed

    Masikini, Milua; Mailu, Stephen N; Tsegaye, Abebaw; Njomo, Njagi; Molapo, Kerileng M; Ikpo, Chinwe O; Sunday, Christopher Edozie; Rassie, Candice; Wilson, Lindsay; Baker, Priscilla G L; Iwuoha, Emmanuel I

    2014-12-30

    An impedimetric immunosensor for fumonisins was developed based on poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes doped with palladium telluride quantum dots onto a glassy carbon surface. The composite was assembled by a layer-by-layer method to form a multilayer film of quantum dots (QDs) and poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes (PDMA-MWCNT). Preparation of the electrochemical immunosensor for fumonisins involved drop-coating of fumonisins antibody onto the composite modified glassy carbon electrode. The electrochemical impedance spectroscopy response of the FB1 immunosensor (GCE/PT-PDMA-MWCNT/anti-Fms-BSA) gave a linear range of 7 to 49 ng L-1 and the corresponding sensitivity and detection limits were 0.0162 kΩ L ng-1 and 0.46 pg L-1, respectively, hence the limit of detection of the GCE/PT-PDMA-MWCNT immunosensor for fumonisins in corn certified material was calculated to be 0.014 and 0.011 ppm for FB1, and FB2 and FB3, respectively. These results are lower than those obtained by ELISA, a provisional maximum tolerable daily intake (PMTDI) for fumonisins (the sum of FB1, FB2, and FB3) established by the Joint FAO/WHO expert committee on food additives and contaminants of 2 μg kg-1 and the maximum level recommended by the U.S. Food and Drug Administration (FDA) for protection of human consumption (2-4 mg L-1).

  13. Reagentless amperometric immunosensors based on direct electrochemistry of horseradish peroxidase for determination of carcinoma antigen-125.

    PubMed

    Dai, Zong; Yan, Feng; Chen, Jin; Ju, Huangxian

    2003-10-15

    A novel strategy for immunoassay and the preparation of reagentless immunosensors was proposed. This strategy was based on the immobilization of antigen and the direct electrochemistry of horseradish peroxidase (HRP) that was labeled to an antibody. A reagentless immunosensor for carcinoma antigen-125 (CA 125) determination was developed. The immunosensor was prepared by immobilizing CA 125 with titania sol-gel on a glassy carbon electrode by the vapor deposition method. The incubation of the immunosensor in phosphate buffer solution (PBS) including HRP-labeled CA 125 antibody led to the formation of a HRP-modified surface. The immobilized HRP displayed its direct electrochemistry with a rate constant of 3.04 +/- 1.21 s(-1). With a competition mechanism, a differential pulse voltammetric determination method for CA 125 was established by the peak current decrease of the immobilized HRP. The current decrease resulted from the competitive binding of the CA 125 in sample solution and the immobilized CA 125 to the limited amount of HRP-labeled CA 125 antibody. Under optimal conditions, the current decrease was proportional to CA 125 concentration ranging from 2 to 14 units mL(-1) with a detection limit of 1.29 units mL(-1) at a current decrease by 10%. The CA 125 immunosensor showed good accuracy and acceptable precision and fabrication reproducibility with intraassay CVs of 8.7 and 5.5% at 8 and 14 units mL(-1) CA 125 concentrations, respectively, and interassay CV of 19.8% at 8 units mL(-1). The storage stability was acceptable in a pH 7.0 PBS at 4 degrees C for 15 days. The proposed method provided a new promising platform for clinical immunoassay.

  14. Human heart failure biomarker immunosensor based on excessively tilted fiber gratings

    PubMed Central

    Luo, Binbin; Wu, Shengxi; Zhang, Zhonghao; Zou, Wengen; Shi, Shenghui; Zhao, Mingfu; Zhong, Nianbing; Liu, Yong; Zou, Xue; Wang, Lingling; Chai, Weina; Hu, Chuanmin; Zhang, Lin

    2016-01-01

    A label-free immunosensor platform based on excessively tilted fiber gratings (Ex-TFGs) was developed for highly specific and fast detection of human N-terminal pro-B-type natriuretic peptide (NT-proBNP), which is considered a powerful biomarker for prognosis and risk stratification of heart failure (HF). High-purity anti-NT-proBNP monoclonal antibodies (MAbs) prepared in our laboratory were immobilized on fiber surface through the staphylococcal protein A (SPA) method for subsequent specific binding of the targeted NT-proBNP. Utilizing fiber optic grating demodulation system (FOGDS), immunoassays were carried out in vitro by monitoring the resonance wavelength shift of Ex-TFG biosensor with immobilized anti-NT-proBNP MAbs. Lowest detectable concentration of ~0.5ng/mL for NT-proBNP was obtained, and average sensitivity for NT-proBNP at a concentration range of 0~1.0 ng/mL was approximately 45.967 pm/(ng/mL). Several human serum samples were assessed by the proposed Ex-TFG biomarker sensor, with high specificity for NT-proBNP, indicating potential application in early diagnosing patients with acute HF symptoms. PMID:28101401

  15. Human heart failure biomarker immunosensor based on excessively tilted fiber gratings.

    PubMed

    Luo, Binbin; Wu, Shengxi; Zhang, Zhonghao; Zou, Wengen; Shi, Shenghui; Zhao, Mingfu; Zhong, Nianbing; Liu, Yong; Zou, Xue; Wang, Lingling; Chai, Weina; Hu, Chuanmin; Zhang, Lin

    2017-01-01

    A label-free immunosensor platform based on excessively tilted fiber gratings (Ex-TFGs) was developed for highly specific and fast detection of human N-terminal pro-B-type natriuretic peptide (NT-proBNP), which is considered a powerful biomarker for prognosis and risk stratification of heart failure (HF). High-purity anti-NT-proBNP monoclonal antibodies (MAbs) prepared in our laboratory were immobilized on fiber surface through the staphylococcal protein A (SPA) method for subsequent specific binding of the targeted NT-proBNP. Utilizing fiber optic grating demodulation system (FOGDS), immunoassays were carried out in vitro by monitoring the resonance wavelength shift of Ex-TFG biosensor with immobilized anti-NT-proBNP MAbs. Lowest detectable concentration of ~0.5ng/mL for NT-proBNP was obtained, and average sensitivity for NT-proBNP at a concentration range of 0~1.0 ng/mL was approximately 45.967 pm/(ng/mL). Several human serum samples were assessed by the proposed Ex-TFG biomarker sensor, with high specificity for NT-proBNP, indicating potential application in early diagnosing patients with acute HF symptoms.

  16. A disposable immunosensor device for point-of-care test of tumor marker based on copper-mediated amplification.

    PubMed

    Ge, Shenguang; Ge, Lei; Yan, Mei; Song, Xianrang; Yu, Jinghua; Liu, Shanshan

    2013-05-15

    A paper-based immunodevice was fabricated for point-of-care test (POCT). The array device was simple and easily assembled. It comprised as many as 4×10 detection points on a single paper array. The immunosensor array was prepared by covalently immobilizing capture antibodies on corresponding working zone on a disposable paper array. With a sandwich-type immunoreaction, the CuO nanoparticles (CuO NPs)-labeled secondary antibody (Ab2) bioconjugates were captured in each working zone. The coordination of dithizone (DZ) at the surface of CdTe quantum dots (CdTe QDs) could strongly quench the green emission of CdTe QDs by a fluorescence resonance energy transfer (FRET) mechanism. After the Cu(2+) was released from CuO NPs-Ab2, the fluorescence of CdTe QDs-DZ was "turn-on". The fluorescence intensity would increase with the increasing of analytes. The calibration plot showed a good linear relationship between the fluorescence intensity and the logarithm value of the analytes concentration with the low detection limit. The immunosensor array was performed for cancer screening. The high throughput, low-cost, acceptable stability, reproducibility, sensitivity and accuracy showed good applicability of the proposed multiplex immunoassay in clinical diagnosis. The results indicated that the device could be applied to comprehensive sample and point-of-care detection. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. A graphene-based electrochemical competitive immunosensor for the sensitive detection of okadaic acid in shellfish

    NASA Astrophysics Data System (ADS)

    Eissa, Shimaa; Zourob, Mohammed

    2012-11-01

    A novel graphene-based voltammetric immunosensor for sensitive detection of okadaic acid (OA) was developed. A simple and efficient electrografting method was utilized to functionalize graphene-modified screen-printed carbon electrodes (GSPE) by the electrochemical reduction of in situ generated 4-carboxyphenyl diazonium salt in acidic aqueous solution. Next, the okadaic acid antibody was covalently immobilized on the carboxyphenyl modified graphene electrodes via carbodiimide chemistry. Square wave voltammetry (SWV) was used to investigate the stepwise assembly of the immunosensor. A competitive assay between OA and a fixed concentration of okadaic acid-ovalbumin conjugate (OA-OVA) for the immobilized antibodies was employed for the detection of okadaic acid. The decrease of the [Fe(CN)6]3-/4- reduction peak current in the square wave voltammetry for various concentrations of okadaic acid was used for establishing the calibration curve. A linear relationship between the SWV peak current difference and OA concentration was obtained up to ~5000 ng L-1. The developed immunosensor allowed a detection limit of 19 ng L-1 of OA in PBS buffer. The matrix effect studied with spiked shellfish tissue extracts showed a good percentage of recovery and the method was also validated with certified reference mussel samples.A novel graphene-based voltammetric immunosensor for sensitive detection of okadaic acid (OA) was developed. A simple and efficient electrografting method was utilized to functionalize graphene-modified screen-printed carbon electrodes (GSPE) by the electrochemical reduction of in situ generated 4-carboxyphenyl diazonium salt in acidic aqueous solution. Next, the okadaic acid antibody was covalently immobilized on the carboxyphenyl modified graphene electrodes via carbodiimide chemistry. Square wave voltammetry (SWV) was used to investigate the stepwise assembly of the immunosensor. A competitive assay between OA and a fixed concentration of okadaic acid

  18. Microfluidic and Label-Free Multi-Immunosensors Based on Carbon Nanotube Microelectrodes

    NASA Astrophysics Data System (ADS)

    Tsujita, Yuichi; Maehashi, Kenzo; Matsumoto, Kazuhiko; Chikae, Miyuki; Takamura, Yuzuru; Tamiya, Eiichi

    2009-06-01

    We fabricated microfluidic and label-free multi-immunosensors by the integration of carbon nanotube (CNT)-arrayed electrodes and microchannels with pneumatic micropumps made of poly(dimethylsiloxane). In the microfluidic systems, four kinds of sample solutions were transported from each liquid inlet to microchannels using six pneumatic micropumps. As a result, two kinds of antibodies were immobilized onto different CNT electrodes using the microfluidic systems. Next, two kinds of cancer markers, prostate specific antigen and human chorionic gonadotropin in phosphate buffer solution, were simultaneously detected by differential pulse voltammetry. Therefore, microfludic multi-immunosensors based on CNT electrodes and pneumatic micropumps are useful for the development of multiplex hand-held biosensors.

  19. A competitive luminol chemiluminescence immunosensor based on a microfluidic chip for the determination of ractopamine.

    PubMed

    Wang, Sai; Chen, Qilong; Wei, Xiao; Wu, Jian; Wang, Chunyan; Liu, Jiahui; Zhang, Liya; Dong, Yiyang

    2017-01-01

    Herein, a competitive luminol chemiluminescence immunosensor based on a microfluidic chip was developed to detect ractopamine (RCT) both in phosphate buffer and swine urine samples. The immunosensor can provide a liner range of 0.5-40 ng/mL and a high sensitivity with a limit of detection of 0.97 ng/mL for RCT detection in swine urine. Good rates of recovery in negative swine urine samples were achieved over the RCT concentration ranging from 0.5 to 40 ng/mL. The proposed method offered a promising analytical scheme for the on-site determination of RCT. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    PubMed

    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.

  1. A multianalyte electrochemical immunosensor based on patterned carbon nanotubes modified substrates for detection of pesticides.

    PubMed

    Liu, Guozhen; Guo, Wenqi; Song, Dandan

    2014-02-15

    A novel multianalyte electrochemical immunosensor based on the assembly of patterned SWNTs on glassy carbon (GC) substrates was developed for simultaneous detection of endosulfan and paraoxon. Based on aryldiazonium salt chemistry, forest of SWNTs can be patterned on GC substrates by C3C bonding using micro contact printing (MCP), which provides an interface showing efficient electron transfer between biomolecules and electrodes. Then redox molecules FDMA and PQQ can be attached to the SWNTs, respectively followed by the attachment of specific epitopes and antibodies. The modified sensing surfaces were characterized by XPS, SEM, AFM and electrochemistry. Based on the current change of specific redox probes, the fabricated immunosensor array can be used for simultaneous detection of endosulfan and paraoxon by a displacement assay. In phosphate buffer solution (50mM, pH 7.0), there is a linear relationship between electrochemical signal of FDMA and the concentration of endosulfan over the range of 0.05-100 ppb with a detection limit of 0.05ppb; the linear range between electrochemical signal of PQQ and the concentration of paraoxon is 2-2500 ppb with a detection limit of 2 ppb. The immunosensor array demonstrates high repeatability, reproducibility, stability and selectivity for the detection of endosulfan and paraoxon.

  2. Graphene-based immunosensor for electrochemical quantification of phosphorylated p53 (S15)

    SciTech Connect

    Xie, Yunying; Chen, Aiqiong; Du, Dan; Lin, Yuehe

    2011-08-01

    We reported a graphene-based immunosensor for electrochemical quantification of phosphorylated p53 on serine 15 (phospho-p5315), a potential biomarker of gamma-radiation exposure. The principle is based on sandwich immunoassay and the resulting immunocomplex is formed among phospho-p53 capture antibody, phospho-p5315 antigen, biotinylated phospho-p5315 detection antibody and horseradish peroxidase (HRP)-labeled streptavidin. The introduced HRP results in an electrocatalytic response to reduction of hydrogen peroxide in the presence of thionine. Graphene served as sensor platform not only promotes electron transfer, but also increases the surface area to introduce a large amount of capture antibody, thus increasing the detection sensitivity. The experimental conditions including blocking agent, immunoreaction time and substrate concentration have been optimized. Under the optimum conditions, the increase of response current is proportional to the phospho-p5315 concentration in the range of 0.2–10 ng mL-1, with the detection limit of 0.1 ng mL-1. The developed immunosensor exhibits acceptable stability and reproducibility and the assay results for phospho-p5315 are in good correlation with the known values. This easily fabricated immunosensor provides a new promising tool for analysis of phospho-p5315 and other phosphorylated proteins.

  3. Flatfish vitellogenin detection using optical waveguide lightmode spectroscopy-based immunosensor.

    PubMed

    Kim, Namsoo; Ryu, Hyung-Seok; Kim, Woo-Yeon

    2007-09-01

    A sensitive optical waveguide lightmode spectroscopy-based immunosensor was developed to detect vitellogenin in seawater flatfish (Paralichthys olivaceus). For this purpose, anion-exchange column chromatography with DE-52 resin was used to purify flatfish vitellogenin from flatfish serum containing vitellogenin that had been induced using an intraperitoneal 17beta-estradiol injection. The anti-flatfish vitellogenin antibody used as the biological component of the above immunosensor was prepared using the purified flatfish vitellogenin. The change in the incoupling angle according to the complexation between the flatfish vitellogenin and its antibody, immobilized over an optical grating coupler sensor chip, was measured to calculate the sensor response. The immunosensor was quite specific to flatfish vitellogenin binding, based on no sensor response in the case of bovine serum albumin immobilization. When plotted using double-logarithmic scales, the sensor responses increased linearly in flatfish vitellogenin concentrations of 0.00675-67.5 nM, with a detection limit of 0.0675 nM. The reusability during seven repetitive measurements was reasonably fair for the preliminary screening of flatfish vitellogenin.

  4. A High Fundamental Frequency (HFF)-based QCM Immunosensor for Tuberculosis Detection.

    PubMed

    Montoya, Angel; March, Carmen; Montagut, Yeison J; Moreno, Maria J; Manclus, Juan J; Arnau, Antonio; Jimenez, Yolanda; Jaramillo, Marisol; Marin, Paula A; Torres, Robinson A

    2017-01-01

    Tuberculosis, one of the oldest diseases affecting human beings, is still considered as a world public health problem by the World Health Organization. Therefore, there is a need for new and more powerful analytical methods for early illness diagnosis. With this idea in mind, the development of a High Fundamental Frequency (HFF) piezoelectric immunosensor for the sensitive detection of tuberculosis was undertaken. A 38 kDa protein secreted by Mycobacterium tuberculosis was first selected as the target biomarker. Then, specific monoclonal antibodies (MAbs) were obtained. Myc-31 MAb, which showed the highest affinity to the analyte, was employed to set up a reference enzyme-linked immunosorbent assay (ELISA) with a limit of detection of 14 ng mL-1 of 38 kDa antigen. For the development of the HFF piezoelectric immunosensor, 100 MHz quartz crystals were used as transducer elements. The gold electrode surface was functionalized by covalent immobilization of the target biomarker through mixed self-assembled monolayers (mSAM) of carboxylic alkane thiols. A competitive immunoassay based on Myc-31 MAb was integrated with the transducer as sensing bio-recognition event. Reliable assay signals were obtained using low concentrations of antigen for functionalization and MAb for the competitive immunoassay. Under optimized conditions, the HFF immunosensor calibration curve for 38 kDa determination showed a limit of detection as low as 11 ng mL-1 of the biomarker. The high detectability attained by this immunosensor, in the picomolar range, makes it a promising tool for the easy, direct and sensitive detection of the tuberculosis biomarker in biological fluids such as sputum. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  5. A Fumonisins Immunosensor Based on Polyanilino-Carbon Nanotubes Doped with Palladium Telluride Quantum Dots

    PubMed Central

    Masikini, Milua; Mailu, Stephen N.; Tsegaye, Abebaw; Njomo, Njagi; Molapo, Kerileng M.; Ikpo, Chinwe O.; Sunday, Christopher Edozie; Rassie, Candice; Wilson, Lindsay; Baker, Priscilla G. L.; Iwuoha, Emmanuel I.

    2015-01-01

    An impedimetric immunosensor for fumonisins was developed based on poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes doped with palladium telluride quantum dots onto a glassy carbon surface. The composite was assembled by a layer-by-layer method to form a multilayer film of quantum dots (QDs) and poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes (PDMA-MWCNT). Preparation of the electrochemical immunosensor for fumonisins involved drop-coating of fumonisins antibody onto the composite modified glassy carbon electrode. The electrochemical impedance spectroscopy response of the FB1 immunosensor (GCE/PT-PDMA-MWCNT/anti-Fms-BSA) gave a linear range of 7 to 49 ng L−1 and the corresponding sensitivity and detection limits were 0.0162 kΩ L ng−1 and 0.46 pg L−1, respectively, hence the limit of detection of the GCE/PT-PDMA-MWCNT immunosensor for fumonisins in corn certified material was calculated to be 0.014 and 0.011 ppm for FB1, and FB2 and FB3, respectively. These results are lower than those obtained by ELISA, a provisional maximum tolerable daily intake (PMTDI) for fumonisins (the sum of FB1, FB2, and FB3) established by the Joint FAO/WHO expert committee on food additives and contaminants of 2 μg kg−1 and the maximum level recommended by the U.S. Food and Drug Administration (FDA) for protection of human consumption (2–4 mg L−1). PMID:25558993

  6. Direct, label-free, selective, and sensitive microbial detection using a bacteriorhodopsin-based photoelectric immunosensor.

    PubMed

    Chen, Hsiu-Mei; Jheng, Kai-Ru; Yu, An-Dih

    2017-05-15

    A photoelectric immunosensor using purple membranes (PM) as the transducer, which contains photoactive bacteriorhodopsin, is here first demonstrated for direct and label-free microbial detection. Biotinylated polyclonal antibodies against Escherichia coli were immobilized on a PM-coated electrode through further surface biotinylation and bridging avidin or NeutrAvidin. The photocurrent generated by the antibody-coated sensor was reduced after incubation with E. coli K-12 cultures, with the reduction level increased with the culture populations. The immunosensor prepared via NeutrAvidin exhibited much better selectivity than the one prepared via avidin, recognizing almost none of the tested Gram-positive bacteria. Cultures with populations ranging from 1 to 10(7)CFU/10mL were detected in a single step without any preprocessing. Both AFM and Raman analysis confirmed the layer-by-layer fabrication of the antibody-coated substrates as well as the binding of microorganisms. By investigating the effect of illumination orientation and simulating the photocurrent responses with an equivalent circuit model containing a chemical capacitance, we suggest that the photocurrent reduction was primarily caused by the light-shielding effect of the captured bacteria. Using the current fabrication technique, versatile bacteriorhodopsin-based photoelectric immunosensors can be readily prepared to detect a wide variety of biological cells.

  7. Two-dimensional paper chromatography-based fluorescent immunosensor for detecting acute myocardial infarction markers.

    PubMed

    Cho, Jung-Hwan; Kim, Min-Ha; Mok, Rak-Sun; Jeon, Jin-Woo; Lim, Guei-Sam; Chai, Chan-Young; Paek, Se-Hwan

    2014-09-15

    A novel washing scheme following antigen-antibody reactions with analyte was used during construction of a fluorescent immunosensor to resolve the background problem in the lateral flow assay with human serum. An immuno-membrane strip was devised to simultaneously measure cardiac troponin I (cTnI), creatinine kinase-MB isoform (CK-MB), and myoglobin to diagnose acute myocardial infarction. This strip was then installed within a cartridge containing a built-in washing solution tank, which was used to supply the solution across the signal generation pad of the strip after the immune reactions. Such cross-flow washing was initiated by onset-signaling from the internal control and began to run automatically upon sample addition. Under optimal conditions, the immunosensor displayed a stably suppressed background baseline, enabling us to attain a low detection limit for cTnI (0.05 ng/mL) as well as favorable reproducibility for repetitive measurements (relative standard deviation <10%). No interference was observed among the different complex formations at the respective analyte sites, and no artifacts were caused by sample matrices. We tested the performance relationship with the Pathfast reference system for positive serum samples (36 for cTnI, 58 for CK-MB, and 17 for myoglobin), and the correlation coefficients were >0.98. This result suggests that the new immunosensor system based on two-dimensional chromatography can be used for clinical testing.

  8. Nanoparticle-based immunosensor with apoferritin templated metallic phosphate label for quantification of phosphorylated acetylcholinesterase

    SciTech Connect

    Du, Dan; Chen, Aiqiong; Xie, Yunying; Zhang, Aidong; Lin, Yuehe

    2011-05-15

    A new sandwich-like electrochemical immunosensor has been developed for quantification of organophosphorylated acetylcholinesterase (OP-AChE), an exposure biomarker of organophosphate pesticides and nerve agents. Zirconia nanoparticles (ZrO2 NPs) were anchored on a screen printed electrode (SPE) to preferably capture OP-AChE adducts by metal chelation with phospho-moieties, which was selectively recognized by lead phosphate-apoferritin labeled anti-AChE antibody (LPA-anti-AChE). The sandwich-like immunoreactions were performed among ZrO2 NPs, OP-AChE and LPA-anti-AChE to form ZrO2/OP-AChE/LPA-anti-AChE complex and the released lead ions were detected on a disposable SPE. The binding affinity was investigated by both square wave voltammetry (SWV) and quartz crystal microbalance (QCM) measurements. The proposed immunosensor yielded a linear response current over a broad OP-AChE concentrations range from 0.05 nM to 10 nM, with detection limit of 0.02 nM, which has enough sensitivity for monitoring of low-dose exposure to OPs. This method avoids the drawback of unavailability of commercial OP-specific antibody as well as amplifies detection signal by using apoferritin encoded metallic phosphate nanoparticle tags. This nanoparticle-based immunosensor offers a new method for rapid, sensitive, selective and inexpensive quantification of phosphorylated adducts for monitoring of OP pesticides and nerve agents exposures.

  9. Troponin T immunosensor based on liquid crystal and silsesquioxane-supported gold nanoparticles.

    PubMed

    Zapp, Eduardo; da Silva, Paulo Sérgio; Westphal, Eduard; Gallardo, Hugo; Spinelli, Almir; Vieira, Iolanda Cruz

    2014-09-17

    A nanostructured immunosensor based on the liquid crystal (E)-1-decyl-4-[(4-decyloxyphenyl)diazenyl]pyridinium bromide (Br-Py) and gold nanoparticles supported by the water-soluble hybrid material 3-n-propyl-4-picolinium silsesquioxane chloride (AuNP-Si4Pic(+)Cl(-)) was built for the detection of troponin T (cTnT), a cardiac marker for acute myocardial infarction (AMI). The functionalized nanostructured surface was used to bind anti-cTnT monoclonal antibodies through electrostatic interaction. The immunosensor (ab-cTnT/AuNP-Si4Pic(+)Cl(-)/Br-Py/GCE) surface was characterized by microscopy techniques. The electrochemical behavior of the immunosensor was studied by cyclic voltammetry and electrochemical impedance spectroscopy. A calibration curve was obtained by square-wave voltammetry. The immnunosensor provided a limit of detection of 0.076 ng mL(-1) and a linear range between 0.1 and 0.9 ng mL(-1) (appropriate for AMI diagnosis).

  10. An amperometric chloramphenicol immunosensor based on cadmium sulfide nanoparticles modified-dendrimer bonded conducting polymer.

    PubMed

    Kim, Dong-Min; Rahman, Md Aminur; Do, Minh Hien; Ban, Changill; Shim, Yoon-Bo

    2010-03-15

    An amperometric chloramphenicol (CAP) immunosensor was fabricated by covalently immobilizing anti-chloramphenicol acetyl transferase (anti-CAT) antibody on cadmium sulfide nanoparticles (CdS) modified-dendrimer that was bonded to the conducting polymer (poly 5, 2': 5', 2''-terthiophene-3'-carboxyl acid (poly-TTCA)) layer. The AuNPs, dendrimers, and CdS nanoparticles were deposited onto the polymer layer in order to enhance the sensitivity of the sensor probes. The particle sizes were determined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The immobilization of dendrimers, CdS, and anti-CAT were confirmed using energy disruptive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and quartz crystal microbalance (QCM) techniques. The detection of CAP was based on the competitive immuno-interaction between the free- and labeled-CAP for active sites of the anti-CAT. Hydrazine was used as the label for CAP, and it electrochemically catalyzed the reduction of H(2)O(2) at -0.35 V vs. Ag/AgCl. Under optimized conditions, the proposed immunosensor exhibited a linear range of CAP detection between 50 pg/mL and 950 pg/mL, and the detection limit was 45 pg/mL. The immunosensor was examined in real meat samples for the analysis of CAP.

  11. Immunosensor based on carbon nanotube/manganese dioxide electrochemical tags.

    PubMed

    Tu, Meng-Che; Chen, Han-Yi; Wang, Yuxi; Moochhala, Shabbir M; Alagappan, Palaniappan; Liedberg, Bo

    2015-01-01

    This article reports on carbon nanotube/manganese dioxide (CNT-MnO2) composites as electrochemical tags for non-enzymatic signal amplification in immunosensing. The synthesized CNT-MnO2 composites showed good electrochemical activity, electrical conductivity and stability. The electrochemical signal of CNT-MnO2 composites coated glassy carbon electrode (GCE) increased by nearly two orders of magnitude compared to bare GCE in hydrogen peroxide (H2O2) environment. CNT-MnO2 composite was subsequently validated as electrochemical tags for sensitive detection of α-fetoprotein (AFP), a tumor marker for diagnosing hepatocellular carcinoma. The electrochemical immunosensor demonstrated a linear response on a log-scale for AFP concentrations ranging from 0.2 to 100 ng mL(-1). The limit of detection (LOD) was estimated to be 40 pg mL(-1) (S/N=3) in PBS buffer. Further measurements using AFP spiked plasma samples revealed the applicability of fabricated CNT-MnO2 composites for clinical and diagnostic applications.

  12. Label-free electrochemical immunosensor based on Nile blue A-reduced graphene oxide nanocomposites for carcinoembryonic antigen detection.

    PubMed

    Gao, Yan-Sha; Zhu, Xiao-Fei; Xu, Jing-Kun; Lu, Li-Min; Wang, Wen-Min; Yang, Tao-Tao; Xing, Hua-Kun; Yu, Yong-Fang

    2016-05-01

    In this article, a novel, label-free, and inherent electroactive redox immunosensor for carcinoembryonic antigen (CEA) based on gold nanoparticles (AuNPs) and Nile blue A (NB) hybridized electrochemically reduced graphene oxide (NB-ERGO) is proposed. The composite of NB-graphene oxide (NB-GO) was prepared by π-π stacking interaction. Then, chronoamperometry was adopted to simultaneously reduce HAuCl4 and nanocomposites of NB-GO for synthesizing AuNPs/NB-ERGO. The immunosensor was fabricated by capturing CEA antibody (anti-CEA) at this nanocomposite modified electrode. The immunosensor determination was based on the fact that, due to the formation of antigen-antibody immunocomplex, the decreased response currents of NB were directly proportional to the concentrations of CEA. Under optimal conditions, the linear range of the proposed immunosensor was estimated to be from 0.001 to 40 ng ml(-1) and the detection limit was estimated to be 0.00045 ng ml(-1). The proposed immunosensor was used to determine CEA in clinical serum samples with satisfactory results. The proposed method may provide promising potential application in clinical immunoassays with the properties of facile procedure, stability, high sensitivity, and selectivity.

  13. A field effect transistor (FET)-based immunosensor for detection of HbA1c and Hb.

    PubMed

    Bian, Chao; Tong, Jianhua; Sun, Jizhou; Zhang, Hong; Xue, Qiannan; Xia, Shanhong

    2011-04-01

    A field effect transistor (FET)-based immunosensor was developed for diabetes monitoring by detecting the concentrations of glycated hemoglobin (HbA1c) and hemoglobin (Hb). This immunosensor consists of a FET-based sensor chip and a disposable extended-gate electrode chip. The sensor chip was fabricated by standard CMOS process and was integrated with signal readout circuit. The disposable electrode chip, fabricated on polyester plastic board by Micro-Electro-Mechanical-Systems (MEMS) technique, was integrated with electrodes array and micro reaction pool. Biomolecules were immobilized on the electrode based on self-assembled monolayer and gold nanoparticles. Experimental results showed that the immunosensor achieved a linear response to HbA1c with the concentration from 4 to 24 μg/ml, and a linear response to Hb with the concentration from 60 to 180 μg/ml.

  14. Ultrasensitive electrochemical immunosensor based on orderly oriented conductive wires for the detection of human monocyte chemotactic protein-1 in serum.

    PubMed

    Li, Yuliang; He, Junlin; Xia, Chunyong; Gao, Liuliu; Yu, Chao

    2015-08-15

    For the first time, a simple, ultrasensitive and label-free electrochemical monocyte chemotactic protein-1 (MCP-1) immunosensor based on orderly oriented conductive wires has been developed. A conductive wire, which is similar to an electron-conducting tunnel, was designed with Au nanoparticles (AuNPs) joined to Au@Pt core-shell microspheres via a cysteamine (CA) crosslinker. To enhance the sensitivity of the immunosensor, Au nanoparticles were electrodeposited onto the gold electrode, and CA was self-assembled via strong Au-S covalent bonds, providing an appropriate surface and promoting electron transfer. Next, Au@Pt core-shell microspheres with large surface area were grafted onto the modified electrode to immobilize more MCP-1 antibodies. MCP-1 is an initiating factor and biomarker of atherosclerotic diseases. Under optimal experimental conditions, differential pulse voltammetry (DPV) current changes were used to detect MCP-1 with a broad linear range of 0.09-360 pg mL(-1) and a low detection limit of 0.03 pg mL(-1) (S/N=3). The proposed immunosensor exhibited good selectivity, reproducibility and reusability. When applied to spiked serum samples, the data for the developed immunosensor were in agreement with an enzyme linked immunosorbent assay, suggesting that the electrochemical immunosensor would be suitable for practical detection.

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

    PubMed

    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.

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

    PubMed Central

    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

    2016-01-01

    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. PMID:27098564

  17. A graphene-based label-free voltammetric immunosensor for sensitive detection of the egg allergen ovalbumin.

    PubMed

    Eissa, Shimaa; L'Hocine, Lamia; Siaj, Mohamed; Zourob, Mohammed

    2013-08-07

    A graphene-based label-free voltammetric immunosensor for the sensitive detection of the egg white allergen ovalbumin has been developed. Graphene-modified screen printed carbon electrodes have been covalently functionalized using electrochemical reduction of in situ generated aryl diazonium salt forming a carboxyphenyl film on the graphene surface. The blocking property of the carboxyphenyl film grafted on to the graphene electrodes using different cyclic voltammetry cycles has been characterized using differential pulse voltammetry in [Fe(CN)6](3-/4-) solution. Then, the terminal carboxylic groups on the graphene surface were activated using EDC/NHS and used to immobilize the ovalbumin antibody and construct the immunosensor. The fabrication steps of the immunosensor have also been characterized using differential pulse voltammetry. The decrease in the [Fe(CN)6](3-/4-) reduction peak current after the immunochemical reaction with ovalbumin has been used for the ovalbumin detection. The developed immunosensor has been used for ovalbumin detection in the concentration range of 1 pg mL(-1) to 0.5 μg mL(-1) with a detection limit of 0.83 pg mL(-1) in PBS buffer. The food matrix effect studied with ovalbumin spiked cake extract showed a good percentage of recovery, indicating the possible applicability of the developed immunosensor in real food samples.

  18. A Label-Free Electrochemical Immunosensor for Carbofuran Detection Based on a Sol-Gel Entrapped Antibody

    PubMed Central

    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. PMID:22163709

  19. An ultrasensitive electrochemical immunosensor for the detection of prostate-specific antigen based on conductivity nanocomposite with halloysite nanotubes.

    PubMed

    Li, Yueyuan; Khan, Malik Saddam; Tian, Lihui; Liu, Li; Hu, Lihua; Fan, Dawei; Cao, Wei; Wei, Qin

    2017-03-01

    A sensitive label-free amperometric electrochemical immunosensor for detection of prostate-specific antigen (PSA) was proposed in this work. The nanocomposite of halloysite nanotubes with polypyrrole shell and palladium nanoparticles (HNTs@PPy-Pd) was used as a novel signal label. The HNTs with adequate hydroxyl groups are economically available raw materials. PPy, as an electrically conducting polymer material, can be absorbed to the surface of HNTs by in situ oxidative polymerization of the pyrrole monomer and form a shell on the HNTs. The shell of PPy could not only improve the conductivity of the nanocomposite but also absorb large amounts of Pd nanoparticles (NPs). The Pd NPs with high electrocatalytic activity toward the reduction of H2O2 and the HNTs@PPy-Pd nanocomposite as the analytical signal label could improve the sensitivity of the immunosensor. Under optimal conditions, the immunosensor showed a low detection limit (0.03 pg/mL) and a wide linear range (0.0001 to 25 ng/mL) of PSA. Moreover, its merits such as good selectivity, acceptable reproducibility, and stability indicate that the fabricated immunosensor has a promising application potential in clinical diagnosis. Graphical Abstract A new label-free amperometric electrochemical immunosensor based on HNTs@PPy-Pd nanocomposite for quantitative detection of PSA.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Solid-state voltammetry-based electrochemical immunosensor for Escherichia coli using graphene oxide-Ag nanoparticle composites as labels.

    PubMed

    Jiang, Xiaochun; Chen, Kun; Wang, Jing; Shao, Kang; Fu, Tao; Shao, Feng; Lu, Donglian; Liang, Jiangong; Foda, M Frahat; Han, Heyou

    2013-06-21

    A new electrochemical immunosensor based on solid-state voltammetry was fabricated for the detection of Escherichia coli (E. coli) by using graphene oxide-Ag nanoparticle composites (P-GO-Ag) as labels. To construct the platform, Au nanoparticles (AuNPs) were first self-assembled on an Au electrode surface through cysteamine and served as an effective matrix for antibody (Ab) attachment. Under a sandwich-type immunoassay format, the analyte and the probe (P-GO-Ag-Ab) were successively captured onto the immunosensor. Finally, the bonded AgNPs were detected through a solid-state redox process in 0.2 M of KCl solution. Combining the advantages of the high-loading capability of graphene oxide with promoted electron-transfer rate of AuNPs, this immunosensor produced a 26.92-fold signal enhancement compared with the unamplified protocol. Under the optimal conditions, the immunosensor exhibited a wide linear dependence on the logarithm of the concentration of E. coli ranging from 50 to 1.0 × 10(6) cfu mL(-1) with a detection limit of 10 cfu mL(-1). Moreover, as a practical application, the proposed immunosensor was used to monitor E. coli in lake water with satisfactory results.

  2. Visible-light driven photoelectrochemical immunosensor for insulin detection based on MWCNTs@SnS2@CdS nanocomposites.

    PubMed

    Liu, Yixin; Zhang, Yifeng; Wu, Dan; Fan, Dawei; Pang, Xuehui; Zhang, Yong; Ma, Hongmin; Sun, Xu; Wei, Qin

    2016-12-15

    In this work, a label-free photoelectrochemical (PEC) immunosensor was developed for ultrasensitive detection of insulin based on MWCNTs@SnS2@CdS nanocomposites. As graphene-like 2D nanomaterial, SnS2 nanosheets loaded on the conducting framework of multi-walled carbon nanotubes (MWCNTs) were adopted for the construction of immunosensor for the first time, providing a favorable substrate for in-situ growth of CdS nanocrystal that had suitable band structure matching well with SnS2. The well-matched band structure of these two metal sulfides effectively inhibited the recombination of photogenerated electron-hole pairs, thus improving the photo-to-current conversion efficiency. Besides, the introduction of MWCNTs facilitated electron transfer across the surface of electrodes, leading to a further increment of photocurrent. The as constructed label-free PEC immunosensor based on MWCNTs@SnS2@CdS nanocomposites exhibited excellent PEC performance for the detection of insulin. The concentrations of insulin could be directly detected based on the decrement of photocurrent that was brought by the increased steric hindrances due to the formation of antigen-antibody immunocomplexes. Under the optimal conditions, the PEC immunosensor had a sensitive response to insulin in a linear range of 0.1pgmL(-1) to 5ngmL(-1) with a detection limit of 0.03pgmL(-1). Meanwhile, good stability and selectivity were achieved as well. The design and fabrication of this PEC immunosensor based on MWCNTs@SnS2@CdS nanocomposites not only provided an ideal platform for the detection of insulin, but also opened up a new avenue for the development of immunosensor for some other biomarkers analysis.

  3. Development and Validation of a Reproducible and Label-Free Surface Plasmon Resonance Immunosensor for Enrofloxacin Detection in Animal-Derived Foods.

    PubMed

    Pan, Mingfei; Li, Shijie; Wang, Junping; Sheng, Wei; Wang, Shuo

    2017-08-30

    This study describes the development of a reproducible and label-free surface plasmon resonance (SPR) immunosensor and its application in the detection of harmful enrofloxacin (ENRO) in animal-derived foods. The experimental parameters for the immunosensor construction and regeneration, including the pH value (4.5), concentration for coating ENRO-ovalbumin conjugate (ENRO-OVA) (100 μg·mL(-1)), concentration of anti-ENRO antibody (80 nM) and regeneration solution (0.1 mol·L(-1) HCl) were evaluated in detail. With the optimized parameters, the proposed SPR immunosensor obtained a good linear response to ENRO with high sensitivity (IC50: 3.8 ng·mL(-1)) and low detection limit (IC15: 1.2 ng·mL(-1)). The proposed SPR immunosensor was further validated to have favorable performances for ENRO residue detection in typical animal-derived foods after a simple matrix pretreatment procedure, as well as acceptable accuracy (recovery: 84.3-96.6%), precision (relative standard deviation (n = 3): 1.8-4.6%), and sensitivity (IC15 ≤ 8.4 ng·mL(-1)). Each SPR chip for analysis can be reused at least 100 times with good stability and the analysis cycle containing the steps of sample uploading/chip regeneration/baseline recovery can be completed within 6 min (one cycle) and auto-operated by a predetermined program. These results demonstrated that the proposed SPR immunosensor provided an effective strategy for accurate, sensitive, and rapid detection for ENRO residue, which has great potential for routine analysis of large numbers of samples for measuring different types of compounds.

  4. Carbon nanotubes-based chemiresistive immunosensor for small molecules: Detection of nitroaromatic explosives

    PubMed Central

    Park, Miso; Cella, Lakshmi N; Chen, Wilfred; Myung, Nosang V.

    2010-01-01

    In recent years, there has been a growing focus on use of one-dimensional (1-D) nanostructures, such as carbon nanotubes and nanowires, as transducer elements for label-free chemiresistive/field-effect transistor biosensors as they provide label-free and high sensitivity detection. While research to-date has elucidated the power of carbon nanotubes- and other 1-D nanostructure- based field effect transistors immunosensors for large charged macromolecules such as proteins and viruses, their application to small uncharged or charged molecules has not been demonstrated. In this paper we report a single-walled carbon nanotubes (SWNTs)-based chemiresistive immunosensor for label-free, rapid, sensitive and selective detection of 2,4,6-trinitrotoluene (TNT), a small molecule. The newly developed immunosensor employed a displacement mode/format in which SWNTs network forming conduction channel of the sensor was first modified with trinitrophenyl (TNP), an analog of TNT, and then ligated with the anti-TNP single chain antibody. Upon exposure to TNT or its derivatives the bound antibodies were displaced producing a large change, several folds higher than the noise, in the resistance/conductance of SWNTs giving excellent limit of detection, sensitivity and selectivity. The sensor detected between 0.5 ppb and 5000 ppb TNT with good selectivity to other nitroaromatic explosives and demonstrated good accuracy for monitoring TNT in untreated environmental water matrix. We believe this new displacement format can be easily generalized to other one-dimensional nanostructure-based chemiresistive immuno/affinity-sensors for detecting small and/or uncharged molecules of interest in environmental monitoring and health care. PMID:20688506

  5. A micro-potentiometric hemoglobin immunosensor based on electropolymerized polypyrrole-gold nanoparticles composite.

    PubMed

    Qu, Lan; Xia, Shanhong; Bian, Chao; Sun, Jizhou; Han, Jinghong

    2009-08-15

    We report a novel micro-potentiometric hemoglobin (Hb) immunosensor based on electrochemically synthesized polypyrrole (PPy)-gold nanoparticles (AuNPs) composite. PPy-AuNPs film with AuNPs uniformly distributed in it was deposited on gold electrode surface by a simple and direct procedure, without the addition of any nanoparticles or reducing agent. And this generic method makes it possible to deposite different polymers on miniaturized electrodes. With the existence of AuNPs, the antibody immobilization onto the electrode surface was facilitated. Morphology study by field emission scanning electron microscope (FE-SEM) confirms the presence of AuNPs in PPy. Based on an ion-sensitive field-effect transistors (ISFETs) integrated chip, a micro-potentiometric immunosensor for Hb and hemoglobin-A1c (HbA1c) has been constructed. The sensor response was linear over the concentration range 60-180 microg/ml Hb and 4-18 microg/ml HbA1c. The Hb concentration in whole blood samples has also been analysed, with a linear dose-response behavior between 125 and 197 microg/ml and a sensitivity of 0.20 mV microg(-1)ml. The measuring ranges of the developed Hb and HbA1c immunosensors meet the clinical demand for measuring the HbA1c/Hb ratio of 5-20%. This sensor results in simple and rapid differential measurement of Hb and HbA1c, and has great potential to become an inexpensive and portable device for monitoring of diabetes.

  6. Ceria Doped Zinc Oxide Nanoflowers Enhanced Luminol-Based Electrochemiluminescence Immunosensor for Amyloid-β Detection.

    PubMed

    Wang, Jing-Xi; Zhuo, Ying; Zhou, Ying; Wang, Hai-Jun; Yuan, Ruo; Chai, Ya-Qin

    2016-05-25

    In this work, ceria doped ZnO nanomaterials with flower-structure (Ce:ZONFs) were prepared to construct a luminol-based electrochemiluminescence (ECL) immunosensor for amyloid-β protein (Aβ) detection. Herein, carboxyl groups (-COOH) covered Ce:ZONFs were synthesized by a green method with lysine as reductant. After that, Ce:ZONFs-based ECL nanocomposite was prepared by combining the luminophore of luminol and Ce:ZONFs via amidation and physical absorption. Luminol modified on Ce:ZONFs surface could generate a strong ECL signal under the assistance of reactive oxygen species (ROSs) (such as OH(•) and O2(•-)), which were produced by a catalytic reaction between Ce:ZONFs and H2O2. It was worth noticing that a quick Ce(4+) ↔ Ce(3+) reaction in this doped material could increase the rate of electron transfer to realize the signal amplification. Subsequently, the luminol functionalized Ce:ZONFs (Ce:ZONFs-Lum) were covered by secondary antibody (Ab2) and glucose oxidase (GOD), respectively, to construct a novel Ab2 bioconjugate (Ab2-GOD@Ce:ZONFs-Lum). The wire-structured silver-cysteine complex (AgCys NWs) with a large number of -COOH, which was synthesized by AgNO3 and l-cysteine, was used as substrate of the immunosensor to capture the primary antibody (Ab1). Under the optimal conditions, this proposed ECL immunosensor had exhibited high sensitivity for Aβ detection with a wide linear range from 80 fg/mL to 100 ng/mL and an ultralow detection limit of 52 fg/mL. Meanwhile, this biosensor had good specificity for Aβ, indicating that the provided strategy had a promising potential in the detection of Aβ.

  7. Development of a Plastic-Based Microfluidic Immunosensor Chip for Detection of H1N1 Influenza

    PubMed Central

    Lee, Kyoung G.; Lee, Tae Jae; Jeong, Soon Woo; Choi, Ho Woon; Heo, Nam Su; Park, Jung Youn; Park, Tae Jung; Lee, Seok Jae

    2012-01-01

    Lab-on-a-chip can provide convenient and accurate diagnosis tools. In this paper, a plastic-based microfluidic immunosensor chip for the diagnosis of swine flu (H1N1) was developed by immobilizing hemagglutinin antigen on a gold surface using a genetically engineered polypeptide. A fluorescent dye-labeled antibody (Ab) was used for quantifying the concentration of Ab in the immunosensor chip using a fluorescent technique. For increasing the detection efficiency and reducing the errors, three chambers and three microchannels were designed in one microfluidic chip. This protocol could be applied to the diagnosis of other infectious diseases in a microfluidic device. PMID:23112630

  8. Double electrochemical covalent coupling method based on click chemistry and diazonium chemistry for the fabrication of sensitive amperometric immunosensor.

    PubMed

    Qi, Honglan; Li, Min; Zhang, Rui; Dong, Manman; Ling, Chen

    2013-08-20

    A double electrochemical covalent coupling method based on click chemistry and diazonium chemistry for the fabrication of sensitive amperometric immunosensor was developed. As a proof-of-concept, a designed alkyne functionalized human IgG was used as a capture antibody and a HRP-labeled rabbit anti-goat IgG was used as signal antibody for the determination of the anti-human IgG using the sandwich model. The immunosensor was fabricated by electrochemically grafting a phenylazide on the surface of a glassy carbon electrode, and then, by coupling the alkyne functionalized human IgG with the phenylazide group through an electro-click chemistry in the presence of Cu(II). The amperometric measurement for the determination of the anti-human IgG was performed after the fabricated immunosensor was incubated with the target anti-human IgG and then with the HRP-labeled anti-goat IgG at -0.25V in 0.10M PBS (pH 7.0) containing 0.1mM hydroquinone and 2.0mM H2O2. The results showed that the increased current was linear with the logarithm of the concentration of the anti-human IgG in the range from 1.0×10(-10)g mL(-1) to 1.0×10(-8)g mL(-1) with a detection limit of 3×10(-11)g mL(-1). Furthermore, the feasibility of the double electrochemical covalent coupling method proposed in this work for fabricating the amperometric immunosensor array was explored. This work demonstrates that the double electrochemical covalent coupling method is a promising approach for the fabrication of the immunosensor and immunosensor array.

  9. Electrochemical signal amplification for immunosensor based on 3D interdigitated array electrodes.

    PubMed

    Han, Donghoon; Kim, Yang-Rae; Kang, Chung Mu; Chung, Taek Dong

    2014-06-17

    We devised an electrochemical redox cycling based on three-dimensional interdigitated array (3D IDA) electrodes for signal amplification to enhance the sensitivity of chip-based immunosensors. The 3D IDA consists of two closely spaced parallel indium tin oxide (ITO) electrodes that are positioned not only on the bottom but also the ceiling, facing each other along a microfluidic channel. We investigated the signal intensities from various geometric configurations: Open-2D IDA, Closed-2D IDA, and 3D IDA through electrochemical experiments and finite-element simulations. The 3D IDA among the four different systems exhibited the greatest signal amplification resulting from efficient redox cycling of electroactive species confined in the microchannel so that the faradaic current was augmented by a factor of ∼100. We exploited the enhanced sensitivity of the 3D IDA to build up a chronocoulometric immunosensing platform based on the sandwich enzyme-linked immunosorbent assay (ELISA) protocol. The mouse IgGs on the 3D IDA showed much lower detection limits than on the Closed-2D IDA. The detection limit for mouse IgG measured using the 3D IDA was ∼10 fg/mL, while it was ∼100 fg/mL for the Closed-2D IDA. Moreover, the proposed immunosensor system with the 3D IDA successfully worked for clinical analysis as shown by the sensitive detection of cardiac troponin I in human serum down to 100 fg/mL.

  10. Amplified impedimetric immunosensor based on instant catalyst for sensitive determination of ochratoxin A.

    PubMed

    Tang, Juan; Huang, Yapei; Zhang, Cengceng; Liu, Huiqiong; Tang, Dianping

    2016-12-15

    A new impedimetric immunosensor for the fast determination of ochratoxin A (OTA) in food samples was developed based on the instant catalyst as enhancer. Initially, the signal tags were prepared via co-immobilization of anti-OTA antibody and amine-terminated dendrimer (PAMAM) on the graphene oxide nanosheets through the covalent interaction, which were utilized as a good platform for combining manganese ion (anti-OTA-GO-PAMAM-Mn(2+)). Upon target OTA introduction, a competitive-type immunoreaction was implemented between the analyte and the immobilized OTA-BSA on the electrode for the anti-OTA antibody on the graphene oxide nanosheets labels. After a competitive immunoassay format, the anti-OTA-GO-PAMAM-Mn(2+) were captured onto the electrode surface, which could induce the in situ formation of MnO2via classical redox reaction between Mn(2+) and KMnO4 on the immunesensing platform. Moreover, the generated MnO2 nanoparticles act as efficient catalyst could catalyze the 4-chloro-1-naphthol (4-CN) oxidation without H2O2 to generate an insoluble precipitation on the platform. Under the optimal conditions, the instant catalyst based impedimetric immunosensor displayed a wide dynamic working range between 0.1pgmL(-1) and 30ngmL(-1). The detection limit (LOD) of the assay was 0.055pgmL(-1). The developed method exhibited high selectivity and can be used for the determination of OTA in real red wine samples.

  11. Detection of Aromatic Nitro Compounds Using Preconcentrator and SPR Immunosensor

    NASA Astrophysics Data System (ADS)

    Onodera, Takeshi; Miyahara, Kazuhisa; Iwakura, Munehiro; Hayashi, Kenshi; Miura, Norio; Matsumoto, Kiyoshi; Toko, Kiyoshi

    In this study, we report the sensitive detection of aromatic nitro compounds using a surface plasmon resonance (SPR) immunosensor based on the indirect competitive method. The vapors from the substances were sampled with a preconcentrator developed here. The solutions of the sampled vapors were measured using SPR immunosensor. Three kinds of explosives such as 2,4-dinitrobenzene, 2,4-dinitrotoluene, and 2,4,6-trinitrotoluene were detected at 1 ppb. Sampling time at 1 l/min was 3 min. Total detection time was brought down to 5 min, which is relatively short for second scanning in landmine detection. Efforts are being made to integrate the SPR immunosensor and preconcentrator for rapid sensitive detection of nitro aromatic compounds under simulated field conditions.

  12. Sulfamethazine detection with direct-binding optical waveguide lightmode spectroscopy-based immunosensor.

    PubMed

    Kim, Namsoo; Kim, Dong-Kyung; Kim, Woo-Yeon

    2008-05-15

    A direct-binding optical waveguide lightmode spectroscopy-based immunosensor detecting sulfamethazine (SMZ) was prepared, followed by the measurement of its specificity and sensitivity. System construction was undertaken with a peristaltic pump, an injector and the main unit comprising a sensor holder, two signal-harvesting photodiodes, a beam mirror, shutter and He-Ne laser source emitting a monochrome light (λ=632.8nm), plus a PC. Antibody immobilization was performed in situ by covalent binding of an anti-SMZ antibody over the surface of a glutaraldehyde-activated 3-aminopropyltriethoxysilane-treated sensor chip. The reaction buffer for the system was 4mM Tris-HCl (pH 7.2) that showed a medium surface coverage and stable baseline. Sensor response was quite specific to antibody-antigen complexation, as judged from no sensor response caused by bovine serum albumin immobilization. The sensor responses according to SMZ concentrations from 10(-8) to 10(-2)M increased linearly in a semi-logarithmic scale, with the limit of detection of 10(-8)M. The immunosensor was favorably reusable for SMZ screening. Copyright © 2007 Elsevier Ltd. All rights reserved.

  13. Electrochemical impedance immunosensor based on three-dimensionally ordered macroporous gold film.

    PubMed

    Chen, Xiaojun; Wang, Yuanyuan; Zhou, Jinjun; Yan, Wei; Li, Xinghua; Zhu, Jun-Jie

    2008-03-15

    A novel label-free immunosensor for the detection of C-reactive protein (CRP) was developed based on a three-dimensional ordered macroporous (3DOM) gold film modified electrode by using the electrochemical impedance spectroscopy (EIS) technique. The electrode was electrochemically fabricated with an inverted opal template, making the surface area of the 3DOM gold film up to 14.4 times higher than that of a classical bare flat one, characterized by the cyclic voltammetric (CV) technique. The 3DOM gold film which was composed of interconnected gold nanoparticles not only has a good biocompatible microenvironment but also promotes the increase of conductivity and stability. The CRP immunosensor was developed by covalently conjugating CRP antibodies with 3-mercaptopropionic acid (MPA) on the 3DOM gold film electrode. The CRP concentration was measured through the increase of impedance values in the corresponding specific binding of CRP antigen and CRP antibody. The increased electron-transfer resistance (R(et)) values were proportional to the logarithmic value of CRP concentrations in the range of 0.1 to 20 ng mL(-1). The detection of CRP levels in three sera obtained from hospital showed acceptable accuracy.

  14. Label-free, ITO-based immunosensor for the detection of a cancer biomarker: Receptor for Activated C Kinase 1.

    PubMed

    Bahadır, E B; Sezgintürk, M K

    2016-10-07

    A new, quite sensitive disposable immunosensor, based on the anti-RACK1 antibody, was developed for the determination of Receptor for Activated C Kinase 1 (RACK1) for the first time. Moreover, indium tin oxide (ITO) flexible sheets were modified by using aldehyde ended silane 11-(triethoxysilyl)undecanal (TESU) self-assembled monolayers (SAMs) for immobilizing the anti-RACK1 antibody via covalent bonds. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV) methods were used for characterizing the immobilization steps and for determining the RACK1 concentration. To obtain a successful immunosensor, experimental factors were optimized. This quite sensitive biosensor was able to detect concentrations as low as fg mL(-1). The detection principle was based on the change in charge transfer resistance and the Nyquist plot diameter and these changes were monitored by using electrochemical impedance spectroscopy (EIS). This impedimetric immunosensor had perfect repeatability and reproducibility. We proved that the new silane agent, TESU, performs well in biosensor applications. The feasibility of the fabricated immunosensor was tested by detecting RACK1 in artificial and real human serum samples.

  15. Development of electrochemical immunosensors based on different serum antibody immobilization methods for detection of Japanese encephalitis virus

    NASA Astrophysics Data System (ADS)

    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.

  16. Immunosensor based on magnetic relaxation switch and biotin-streptavidin system for the detection of Kanamycin in milk.

    PubMed

    Chen, Yi Ping; Zou, Ming qiang; Qi, Cai; Xie, Meng-Xia; Wang, Da-Ning; Wang, Yan-Fei; Xue, Qiang; Li, Jin-Feng; Chen, Yan

    2013-01-15

    A rapid, sensitive, and simple immunosensor was developed for the detection of Kanamycin (KM) in milk. This immunosensor is based on magnetic relaxation switch (MRS) assay and biotin-streptavidin system (B-SA system). The target analyte (KM) competed with those on the surface of the superparamagnetic iron oxide (SPIO) nanoparticles and hence affected the formation of SPIO aggregates. The dispersed and aggregated states of SPIO can modulate the spin-spin relaxation time (T(2)) of the neighboring water molecule. T(2) was then changed as an effect of the target analyte. The B-SA system was used to amplify the SPIO binding, thus enhance the sensitivity. The detection working was 1.5 to 25.2ng mL(-1) and limit of detection (LOD) was determined to be 0.1ng mL(-1). The LOD of the immunosensor decreased tenfold, and its analysis time (45min) was much shorter than that of enzyme-linked immunosorbent assay (6h to 8h). The average recoveries of the KM at various spiking levels ranged from 80.2% to 85.6% with a relative standard deviation (RSD) below 4.0%. The results showed that the MRS immunosensor was a promising platform for the determination of small molecular residues because of its high sensitivity, specificity, homogeneity, and speed.

  17. Amperometric immunosensor based on multiwalled carbon nanotubes/Prussian blue/nanogold-modified electrode for determination of α-fetoprotein.

    PubMed

    Jiang, Wen; Yuan, Ruo; Chai, Ya-Qin; Yin, Bing

    2010-12-01

    In this article, a conspicuously simple and highly sensitive amperometric immunosensor based on the sequential electrodeposition of Prussian blue (PB) and gold nanoparticles (GNPs) on multiwalled carbon nanotube (MWCNT)-modified glassy carbon electrode (GCE) surface is proposed for the detection of α-fetoprotein (AFP). By comparison with PB, the MWCNT/PB composite film had been proven to show much better electrochemical stability and a larger response current. The electrodeposited GNP film can be used not only to immobilize biomolecules but also to avoid the leakage of PB and to prevent shedding of MWCNT/PB composite film from the electrode surface. The performance and factors influencing the performance of the immunosensor were investigated. Under optimal experimental conditions, the proposed immunosensor for AFP was observed with an ultralow limit of detection (LOD) equal to 3 pg/ml (at 3δ), and the linear working range spanned the concentrations of AFP from 0.01 to 300 ng/ml. Moreover, the immunosensor, as well as a commercially available kit, was examined for use in the determination of AFP in real human serum specimens. More significant, the assay mentioned here is simpler than the traditional enzyme-linked immunosorbent assay (ELISA), and an excellent correlation of levels of AFP measured was obtained, indicating that the developed immunoassay could be a promising alternative approach for detection of AFP and other tumor markers in the clinical diagnosis.

  18. Highly sensitive luminol electrochemiluminescence immunosensor based on ZnO nanoparticles and glucose oxidase decorated graphene for cancer biomarker detection.

    PubMed

    Cheng, Yinfeng; Yuan, Ruo; Chai, Yaqin; Niu, Huan; Cao, Yaling; Liu, Huijing; Bai, Lijuan; Yuan, Yali

    2012-10-01

    In this work, we reported a sandwiched luminol electrochemiluminescence (ECL) immunosensor using ZnO nanoparticles (ZnONPs) and glucose oxidase (GOD) decorated graphene as labels and in situ generated hydrogen peroxide as coreactant. In order to construct the base of the immunosensor, a hybrid architecture of Au nanoparticles and graphene by reduction of HAuCl(4) and graphene oxide (GO) with ascorbic acid was prepared. The resulted hybrid architecture modified electrode provided an excellent platform for immobilization of antibody with good bioactivity and stability. Then, ZnONPs and GOD functionalized graphene labeled secondary antibody was designed for fabricating a novel sandwiched ECL immunosensor. Enhanced sensitivity was obtained by in situ generating hydrogen peroxide with glucose oxidase and the catalysis of ZnONPs to the ECL reaction of luminol-H(2)O(2) system. The as-prepared ECL immunosensor exhibited excellent analytical property for the detection of carcinoembryonic antigen (CEA) in the range from 10 pg mL(-1) to 80 ng mL(-1) and with a detection limit of 3.3 pg mL(-1) (SN(-1)=3). The amplification strategy performed good promise for clinical application of screening of cancer biomarkers.

  19. Ultrasensitive non-enzymatic immunosensor for carcino-embryonic antigen based on palladium hybrid vanadium pentoxide/multiwalled carbon nanotubes.

    PubMed

    Han, Jian; Jiang, Liping; Li, Faying; Wang, Ping; Liu, Qing; Dong, Yunhui; Li, Yueyun; Wei, Qin

    2016-03-15

    A novel and sensitive sandwich-type non-enzymatic electrochemical immunosensor was fabricated for quantitative monitoring of carcino-embryonic antigen (CEA). Nanocomposite of stannic oxide/reduced graphene oxide was used as substrate material to increase the specific surface area and enhance the conductivity of the glassy carbon electrode. Gold nanoparticles (Au NPs) were introduced to link substrate materials and primary antibodies (Ab1) and accelerate the electron transfer in this system. At the same time, the palladium nanoparticles (Pd NPs)-vanadium pentoxide (V2O5)/multiwalled carbon nanotubes (MWCNTs) were used as the label of secondary antibodies (Ab2). This composite label has shown excellent catalytic activity towards the reduction of H2O2. The nanomaterial-based signal amplification can improve the sensitivity and lower the limit of detection. The proposed immunosensor showed wide linear range from 0.5 pgmL(-1) to 25 ngmL(-1) with limit of detection of 0.17 pgmL(-1). This novel immunosensor was used to analyze serum sample. The results indicated that this immunosensor may find huge potential application for quantitative detection of CEA in the clinical diagnosis.

  20. A droplet-based microfluidic immunosensor for high efficiency melamine analysis.

    PubMed

    Choi, Jae-Won; Min, Kyong-Mi; Hengoju, Sundar; Kim, Gil-Jung; Chang, Soo-Ik; deMello, Andrew J; Choo, Jaebum; Kim, Hak Yong

    2016-06-15

    We report a droplet-based microfluidic immunosensor for the rapid and accurate detection of melamine, an organic base that has been implicated in widescale adulteration of food products such as milk. Our melamine assay is based on the competitive reaction between native melamine and a melamine-fluorescein isothiocyanate (FITC) conjugate against an anti-hapten antibody. The adoption of fluorescence polarization, allows the quantification of melamine in a more direct and rapid manner than established heterogeneous methods based on liquid chromatography, mass spectrometry, and enzyme-linked immunosorbent assay (ELISA). The detection protocol provides a limit of detection of 300 ppb, which is below the maximum allowable melamine levels (2.5 ppm) defined by the U.S. Food and Drug Administration and the European Commission to a significant extent. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Optical immunosensor for endocrine disruptor nanolayer detection by surface plasmon resonance imaging

    NASA Astrophysics Data System (ADS)

    Karabchevsky, Alina; Tsapovsky, Lev; Marks, Robert S.; Abdulhalim, Ibrahim

    2011-10-01

    Endocrine disrupting compounds (EDCs) such as bisphenol A (BPA) and female hormone Estrone are especially prevalent in surface and waste-waters in nano-molar concentrations and therefore, there is a need for sensitive analytical device for their monitoring. We have designed a miniature, low cost and fast surface plasmon resonance (SPR) imaging liquid sensor based on the angular interrogation using Kretschmann configuration with diverged incident monochromatic light. During this paper we present a surface plasmon resonance imaging (SPRI) biosensor to detect EDCs such as BPA and estrone. A pattern of SPR line which is dark intensity line on bright area was reflected at angles range depending on the dielectric constant of the analye: Rabbit Anti-Estrone polyclonal IgG + Estrone 11-MUA attached to the silver or non-specific sensing of BPA in water with nanoprecision. For analyzing the SPR signals we used an efficient detection algorithm based on Radon Transform with less sensitivity to laser speckle noise and nonuniformity of the illumination.

  2. Nanoparticle-Based Electrochemical Immunosensor for Detection of Phosphorylated Acetylcholinesterase: An Exposure Biomarker of Organophosphate Pesticides and Nerve Agents

    PubMed Central

    Liu, Guodong; Wang, Jun; Barry, Richard; Petersen, Catherine; Timchalk, Charles; Gassman, Paul L; Lin, Yuehe

    2009-01-01

    A nanoparticle-based electrochemical immunosensor has been developed for the detection of phosphorylated acetylcholinesterase (AChE), which is a potential exposure biomarker for organophosphate (OP) pesticides and chemical warfare nerve agent exposures. Zirconia nanoparticles (ZrO2 NPs) were used as selective sorbents to capture the phosphorylated AChE adduct, and quantum dots (ZnS@CdS, QDs) were used as tags to label monoclonal anti-AChE antibody to quantify the immunorecognition events. The sandwich-like immunoreactions were performed among the ZrO2 NPs, which were pre-coated on a screen printed electrode (SPE) by electrodeposition, phosphorylated AChE and QD-anti-AChE. The captured QD tags were determined on the SPE by electrochemical stripping analysis of its metallic component (cadmium) after an acid-dissolution step. Paraoxon was used as the model OP insecticide to prepare the phosphorylated AChE adducts to demonstrate proof of principle for the sensor. The phosphorylated AChE adduct was characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Mass Spectroscopy. The binding affinity of anti-AChE to the phosphorylated AChE was validated with an enzyme-linked immunosorbent assay. The parameters (e.g., amount of ZrO2 NP, QD-anti-AChE concentration,) that govern the electrochemical response of immunosensors were optimized. The voltammetric response of the immunosensor is highly linear over the range of 10 pM to 4 nM phosphorylated AChE, and the limit of detection is estimated to be 8.0 pM. The immunosensor was also successfully applied for the detection of phosphorylated AChE in human plasma sample. This new nanoparticle-based electrochemical immunosensor provides an opportunity to develop field-deployable, sensitive, and quantitative biosensors for monitoring exposure to a variety of OP pesticides and nerve agents. PMID:18942695

  3. Nanoparticle-based electrochemical immunosensor for the detection of phosphorylated acetylcholinesterase: an exposure biomarker of organophosphate pesticides and nerve agents.

    PubMed

    Liu, Guodong; Wang, Jun; Barry, Richard; Petersen, Catherine; Timchalk, Charles; Gassman, Paul L; Lin, Yuehe

    2008-01-01

    A nanoparticle-based electrochemical immunosensor has been developed for the detection of phosphorylated acetylcholinesterase (AChE), which is a potential biomarker of exposure to organophosphate (OP) pesticides and chemical warfare nerve agents. Zirconia nanoparticles (ZrO(2) NPs) were used as selective sorbents to capture the phosphorylated AChE adduct, and quantum dots (ZnS@CdS, QDs) were used as tags to label monoclonal anti-AChE antibody to quantify the immunorecognition events. The sandwich-like immunoreactions were performed among the ZrO(2) NPs, which were pre-coated on a screen printed electrode (SPE) by electrodeposition, phosphorylated AChE and QD-anti-AChE. The captured QD tags were determined on the SPE by electrochemical stripping analysis of its metallic component (cadmium) after an acid-dissolution step. Paraoxon was used as the model OP insecticide to prepare the phosphorylated AChE adducts to demonstrate proof of principle for the sensor. The phosphorylated AChE adduct was characterized by Fourier transform infrared spectroscopy (FTIR) and mass spectroscopy. The binding affinity of anti-AChE to the phosphorylated AChE was validated with an enzyme-linked immunosorbent assay. The parameters (e.g., amount of ZrO(2) NP, QD-anti-AChE concentration,) that govern the electrochemical response of immunosensors were optimized. The voltammetric response of the immunosensor is highly linear over the range of 10 pM to 4 nM phosphorylated AChE, and the limit of detection is estimated to be 8.0 pM. The immunosensor also successfully detected phosphorylated AChE in human plasma. This new nanoparticle-based electrochemical immunosensor provides an opportunity to develop field-deployable, sensitive, and quantitative biosensors for monitoring exposure to a variety of OP pesticides and nerve agents.

  4. Positive potential operation of a cathodic electrogenerated chemiluminescence immunosensor based on luminol and graphene for cancer biomarker detection.

    PubMed

    Xu, Shoujiang; Liu, Yang; Wang, Taihong; Li, Jinghong

    2011-05-15

    In this work, we report a cathodic electrogenerated chemiluminescence (ECL) of luminol at a positive potential (ca. 0.05 V vs Ag/AgCl) with a strong light emission on the graphene-modified glass carbon electrode. The resulted graphene-modified electrode offers an excellent platform for high-performance biosensing applications. On the basis of the cathodic ECL signal of luminol on the graphene-modified electrode, an ECL sandwich immunosensor for sensitive detection of cancer biomarkers at low potential was developed with a multiple signal amplification strategy from functionalized graphene and gold nanorods multilabeled with glucose oxidase (GOx) and secondary antibody (Ab(2)). The functionalized graphene improved the electron transfer on the electrode interface and was employed to attach the primary antibody (Ab(1)) due to it large surface area. The gold nanorods were not only used as carriers of secondary antibody (Ab(2)) and GOx but also catalyzed the ECL reaction of luminol, which further amplified the ECL signal of luminol in the presence of glucose and oxygen. The as-proposed low-potential ECL immunosensor exhibited high sensitivity and specificity on the detection of prostate protein antigen (PSA), a biomarker of prostate cancer that was used as a model. A linear relationship between ECL signals and the concentrations of PSA was obtained in the range from 10 pg mL(-1) to 8 ng mL(-1). The detection limit of PSA was 8 pg mL(-1) (signal-to-noise ratio of 3). Moreover, the as-proposed low-potential ECL immunosensor exhibited excellent stability and reproducibility. The graphene-based ECL immunosensor accurately detected PSA concentration in 10 human serum samples from patients demonstrated by excellent correlations with standard chemiluminescence immunoassay. The results suggest that the as-proposed graphene ECL immunosensor will be promising in the point-of-care diagnostics application of clinical screening of cancer biomarkers.

  5. Towards an Electronic Dog Nose: Surface Plasmon Resonance Immunosensor for Security and Safety

    PubMed Central

    Onodera, Takeshi; Toko, Kiyoshi

    2014-01-01

    This review describes an “electronic dog nose” based on a surface plasmon resonance (SPR) sensor and an antigen–antibody interaction for security and safety. We have concentrated on developing appropriate sensor surfaces for the SPR sensor for practical use. The review covers different surface fabrications, which all include variations of a self-assembled monolayer containing oligo(ethylene glycol), dendrimer, and hydrophilic polymer. We have carried out detection of explosives using the sensor surfaces. For the SPR sensor to detect explosives, the vapor or particles of the target substances have to be dissolved in a liquid. Therefore, we also review the development of sampling processes for explosives, and a protocol for the measurement of explosives on the SPR sensor in the field. Additionally, sensing elements, which have the potential to be applied for the electronic dog nose, are described. PMID:25198004

  6. A novel electrochemiluminescent immunosensor based on the quenching effect of aminated graphene on nitrogen-doped carbon quantum dots.

    PubMed

    Zhou, Jing; Han, Tongqian; Ma, Hongmin; Yan, Tao; Pang, Xuehui; Li, Yueyun; Wei, Qin

    2015-08-19

    Nitrogen-doped carbon quantum dots (N-CQDs) with an average diameter of 2 nm were synthesized by carbonization of diethylene triamine pentacetate acid (DTPA). The simple prepared N-CQDs showed excellent electrochemiluminescence (ECL) property and were used as luminophors to fabricate a sandwich-type ECL immunosensor. Aminated graphene (NH2-G) was also synthesized and used as a label of secondary antibody. The labeled NH2-G could effectively quench the ECL of N-CQDs modified on electrodes due to ECL resonance energy transfer (ERET). Immunological recognition which induced ECL quenching enabled the quantitative determination of biomarkers. Alpha fetoprotein (AFP) was selected as a model analyte to investigate the analytical performance of the proposed immunosensor. Under optimal conditions, a good linear relationship between ECL intensity and the logarithm of AFP concentration was obtained in the range of 0.01-100 ng mL(-1) with the detection limit of 3.3 pg mL(-1). The proposed ECL immunosensor showed good stability, acceptable selectivity and reproducibility. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Rapid and Highly Sensitive Detection of Lead Ions in Drinking Water Based on a Strip Immunosensor

    PubMed Central

    Kuang, Hua; Xing, Changrui; Hao, Changlong; Liu, Liqiang; Wang, Libing; Xu, Chuanlai

    2013-01-01

    In this study, we have first developed a rapid and sensitive strip immunosensor based on two heterogeneously-sized gold nanoparticles (Au NPs) probes for the detection of trace lead ions in drinking water. The sensitivity was 4-fold higher than that of the conventional LFA under the optimized conditions. The visual limit of detection (LOD) of the amplified method for qualitative detection lead ions was 2 ng/mL and the LOD for semi-quantitative detection could go down to 0.19 ng/mL using a scanning reader. The method suffered from no interference from other metal ions and could be used to detect trace lead ions in drinking water without sample enrichment. The recovery of the test samples ranged from 96% to 103%. As the detection method could be accomplished within 15 min, this method could be used as a potential tool for preliminary monitoring of lead contamination in drinking water. PMID:23539028

  8. Rapid and highly sensitive detection of lead ions in drinking water based on a strip immunosensor.

    PubMed

    Kuang, Hua; Xing, Changrui; Hao, Changlong; Liu, Liqiang; Wang, Libing; Xu, Chuanlai

    2013-03-28

    In this study, we have first developed a rapid and sensitive strip immunosensor based on two heterogeneously-sized gold nanoparticles (Au NPs) probes for the detection of trace lead ions in drinking water. The sensitivity was 4-fold higher than that of the conventional LFA under the optimized conditions. The visual limit of detection (LOD) of the amplified method for qualitative detection lead ions was 2 ng/mL and the LOD for semi-quantitative detection could go down to 0.19 ng/mL using a scanning reader. The method suffered from no interference from other metal ions and could be used to detect trace lead ions in drinking water without sample enrichment. The recovery of the test samples ranged from 96% to 103%. As the detection method could be accomplished within 15 min, this method could be used as a potential tool for preliminary monitoring of lead contamination in drinking water.

  9. Ultrasensitive IL-6 electrochemical immunosensor based on Au nanoparticles-graphene-silica biointerface.

    PubMed

    Wang, Guangfeng; He, Xiuping; Chen, Ling; Zhu, Yanhong; Zhang, Xiaojun

    2014-04-01

    An Interleukin-6 (IL-6) electrochemical immunosensor was fabricated based on the Au nanoparticles (AuNP)-graphene-silica sol-gel as immobilization biointerface and AuNP-polydopamine (PDA)@carbon nanotubes (CNT) as the label of HRP-bound antibodies. The AuNP-graphene-silica sol-gel film was prepared in situ and modified on the ITO electrode, providing a stable network for the immobilization of antibody and exhibiting a dynamic working range of 1-40 pg/mL with a low detection limit of 0.3 pg/mL IL-6 (at 3s). The results of serum samples with the sensor received an acceptable agreement with the ELISA method. Importantly, this method provided a promising ultrasensitive assay strategy for clinical applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Nanoparticle-based immunosensors and immunoassays for aflatoxins.

    PubMed

    Wang, Xu; Niessner, Reinhard; Tang, Dianping; Knopp, Dietmar

    2016-03-17

    Aflatoxins are naturally existing mycotoxins produced mainly by Aspergillus flavus and Aspergillus parasiticus, present in a wide range of food and feed products. Because of their extremely high toxicity and carcinogenicity, strict control of maximum residue levels of aflatoxins in foodstuff is set by many countries. In daily routine, different chromatographic methods are used almost exclusively. As supplement, in several companies enzyme immunoassay-based sample testing as primary screening is performed. Recently, nanomaterials such as noble metal nanoparticles, magnetic particles, carbon nanomaterials, quantum dots, and silica nanomaterials are increasingly utilized for aflatoxin determination to improve the sensitivity and simplify the detection. They are employed either as supports for the immobilization of biomolecules or as electroactive or optical labels for signal transduction and amplification. Several nanoparticle-based electrochemical, piezoelectric, optical, and immunodipstick assays for aflatoxins have been developed. In this review, we summarize these recent advances and illustrate novel concepts and promising applications in the field of food safety.

  11. Electrochemical cortisol immunosensors based on sonochemically synthesized zinc oxide 1D nanorods and 2D nanoflakes.

    PubMed

    Vabbina, Phani Kiran; Kaushik, Ajeet; Pokhrel, Nimesh; Bhansali, Shekhar; Pala, Nezih

    2015-01-15

    We report on label free, highly sensitive and selective electrochemical immunosensors based on one-dimensional 1D ZnO nanorods (ZnO-NRs) and two-dimensional 2D ZnO nanoflakes (ZnO-NFs) which were synthesized on Au-coated substrates using simple one step sonochemical approach. Selective detection of cortisol using cyclic voltammetry (CV) is achieved by immobilizing anti-cortisol antibody (Anti-C(ab)) on the ZnO nanostructures (NSs). 1D ZnO-NRs and 2D ZnO-NFs provide unique sensing advantages over bulk materials. While 1D-NSs boast a high surface area to volume ratio, 2D-NSs with large area in polarized (0001) plane and high surface charge density could promote higher Anti-C(ab) loading and thus better sensing performance. Beside large surface area, ZnO-NSs also exhibit higher chemical stability, high catalytic activity, and biocompatibility. TEM studies showed that both ZnO-NSs are single crystalline oriented in (0001) plane. The measured sensing parameters are in the physiological range with a sensitivity of 11.86 µA/M exhibited by ZnO-NRs and 7.74 µA/M by ZnO-NFs with the lowest detection limit of 1 pM which is 100 times better than conventional enzyme-linked immunosorbant immunoassay (ELISA). ZnO-NSs based cortisol immunosensors were tested on human saliva samples and the performance were validated with conventional (ELISA) method which exhibits a remarkable correlation. The developed sensors can be integrated with microfluidic system and miniaturized potentiostat for point-of-care cortisol detection and such developed protocol can be used in personalized health monitoring/diagnostic.

  12. A supersandwich electrochemiluminescence immunosensor based on mimic-intramolecular interaction for sensitive detection of proteins.

    PubMed

    He, Ying; Chai, Yaqin; Yuan, Ruo; Wang, Haijun; Bai, Lijuan; Liao, Ni

    2014-10-21

    An electrochemiluminescence (ECL) immunoassay protocol was developed based on mimic-intramolecular interaction for sensitive detection of prostate specific antigen (PSA). It was constructed by integrating the ECL luminophore (tris(4,4'-dicarboxylicacid-2,2'-bipyridyl)-ruthenium(ii)dichloride (Ru(dcbpy)3(2+))) and coreactant (histidine) into the supersandwich DNA structure. This strategy was more effective in amplifying the ECL signal by shortening the electronic transmission distance, improving the ECL luminous stability and enhancing the ECL luminous efficiency. The ECL matrices denoted as MWCNTs@PDA-AuNPs were fabricated through spontaneous oxidative polymerization of dopamine (DA) on multiwalled carbon nanotubes (MWCNTs) and reducing HAuCl4 to produce gold nanoparticles (AuNPs) by DA simultaneously. Then, the prepared matrices were applied to bind capture antibodies. Moreover, supersandwich Ab2 bioconjugate was designed using a PAMAM dendrimer to immobilize the detection antibody and supersandwich DNA structure. The PAMAM dendrimer, with a plurality of secondary and tertiary amine groups, not only facilitated high-density immobilization of the detection antibody and supersandwich DNA structure, but also greatly amplified the ECL signal of Ru(dcbpy)3(2+). The supersandwich DNA structure contained multiple Ru(dcbpy)3(2+) and histidine, further amplifying the ECL signal. The proposed supersandwich immunosensor showed high sensitivity with a detection limit of 4.2 fg mL(-1) and a wide linear range of 0.01 pg mL(-1)-40.00 ng mL(-1). With the excellent stability, satisfying precision and reproducibility, the proposed immunosensor indicates promising practicability for clinical diagnosis.

  13. Disposable immunosensors for C-reactive protein based on carbon nanotubes field effect transistors.

    PubMed

    Justino, Celine I L; Freitas, Ana C; Amaral, José P; Rocha-Santos, Teresa A P; Cardoso, Susana; Duarte, Armando C

    2013-04-15

    Label-free immunosensors based on single-walled carbon nanotubes field effect transistor (NTFET) devices were developed for the detection of C-reactive protein (CRP) which is currently the best validated inflammatory biomarker associated with cardiovascular diseases. The immunoreaction principle consists in the direct adsorption of CRP specific antibodies (anti-CRP) to single-walled carbon nanotubes (SWCNTs) networks. Such anti-CRP are the molecular receptors of CRP antigens which, in turn, can be detected by the developed NTFET devices in a linear dynamic range of 10(-4)-10(2) μg/mL. Thus, typical values of CRP (in blood serum) for healthy persons (<1 μg/mL), and higher levels (>5 μg/mL) corresponding to pathological states, can be both detected with the NTFET immunosensors, becoming an advantageous alternative as the basis for the development of analytical instrumentation for assessment of risk of occurrence of cardiovascular diseases. A log-log linear regression was applied to the experimental data with a correlation coefficient of r=0.9962 (p<0.001), and there is no statistical difference (from ANOVA) between individual NTFET devices (p=0.9582), demonstrating acceptable reproducibility. According to the experimental results, the estimate of detection limit (LOD, 10(-4)μg/mL) is 3-fold lower than that of some conventional immunoassay techniques for blood serum (e.g., LOD of 0.2 μg/mL for high-sensitivity enzyme-linked immunosorbent assay), and the dynamic range (10(-4)-10(2)μg/mL) is about 6-fold higher. Furthermore, this simple and low-cost methodology allows the use of sample volumes as low as 1 μL for the label-free detection of CRP.

  14. Sensitive immunosensor for tumor necrosis factor α based on dual signal amplification of ferrocene modified self-assembled peptide nanowire and glucose oxidase functionalized gold nanorod.

    PubMed

    Sun, Zhifang; Deng, Liu; Gan, Hao; Shen, Rujuan; Yang, Minghui; Zhang, Yi

    2013-01-15

    Sensitive electrochemical immunosensor for the detection of protein biomarker tumor necrosis factor α (TNF-α) was reported that uses ferrocene carboxylic acid (Fc) functionalized self-assembled peptide nanowire (Fc-PNW) as sensor platform and glucose oxidase (GOx) modified gold nanorod (GNR) as label. Greatly enhanced sensitivity is achieved based on a dual signal amplification strategy: first, the synthesized Fc-PNW used as the sensor platform increased the loading of primary anti-TNF-α antibody (Ab(1)) onto electrode surface due to its large surface area. At the same time, the Fc moiety on the nanowire is used as a mediator for GOx to catalyze the glucose reaction. Second, multiple GOx and secondary anti-TNF-α antibody (Ab(2)) molecules are bounded onto each GNR to increase the sensitivity of the immunosensor. After the preparation of the immunosensor based on the traditional sandwich protocol, the response of the immunosensor towards glucose was used as a signal to differentiate various concentrations of TNF-α. The resulting immunosensor has high sensitivity, wide linear range (0.005-10ng/mL) and good selectivity. This immunosensor preparation strategy is a promising platform for clinical screening of protein biomarkers.

  15. Label-Free Detection of Human Glycoprotein (CgA) Using an Extended-Gated Organic Transistor-Based Immunosensor

    PubMed Central

    Minamiki, Tsukuru; Minami, Tsuyoshi; Sasaki, Yui; Wakida, Shin-ichi; Kurita, Ryoji; Niwa, Osamu; Tokito, Shizuo

    2016-01-01

    Herein, we report on the fabrication of an extended-gated organic field-effect transistor (OFET)-based immunosensor and its application in the detection of human chromogranin A (hCgA). The fabricated OFET device possesses an extended-gate electrode immobilized with an anti-CgA antibody. The titration results of hCgA showed that the electrical changes in the OFET characteristics corresponded to the glycoprotein recognition ability of the monoclonal antibody (anti-CgA). The observed sensitivity (detection limit: 0.11 µg/mL) and selectivity indicate that the OFET-based immunosensor can be potentially applied to the rapid detection of the glycoprotein concentration without any labeling. PMID:27916899

  16. Label-Free Detection of Human Glycoprotein (CgA) Using an Extended-Gated Organic Transistor-Based Immunosensor.

    PubMed

    Minamiki, Tsukuru; Minami, Tsuyoshi; Sasaki, Yui; Wakida, Shin-Ichi; Kurita, Ryoji; Niwa, Osamu; Tokito, Shizuo

    2016-11-30

    Herein, we report on the fabrication of an extended-gated organic field-effect transistor (OFET)-based immunosensor and its application in the detection of human chromogranin A (hCgA). The fabricated OFET device possesses an extended-gate electrode immobilized with an anti-CgA antibody. The titration results of hCgA showed that the electrical changes in the OFET characteristics corresponded to the glycoprotein recognition ability of the monoclonal antibody (anti-CgA). The observed sensitivity (detection limit: 0.11 µg/mL) and selectivity indicate that the OFET-based immunosensor can be potentially applied to the rapid detection of the glycoprotein concentration without any labeling.

  17. Nanoporous PtCo-based ultrasensitive enzyme-free immunosensor for zeranol detection.

    PubMed

    Feng, Rui; Zhang, Yong; Yu, Haiqin; Wu, Dan; Ma, Hongmin; Zhu, Baocun; Xu, Caixia; Li, He; Du, Bin; Wei, Qin

    2013-04-15

    Nanoporous PtCo alloy was designed as an antibody carrier for preparation of a highly sensitive immunosensor. The immunosensor was constructed by assembling the capture zeranol antibody on thionine decorated graphene nanosheets modified glassy carbon electrode. With an enzyme-free immunosensor mode, the nanoporous PtCo alloy, synthesized by dealloying method, had shown strong electrocatalytic activity toward antigen-antibody reaction. The use of PtCo alloy carrier offered a high amount of antibody on each immunoconjugate, hence amplified the detectable signal from the electro-reaction of dissolved oxygen. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the recognition of zeranol. Due to the poor conductivity of zeranol, a small amount of zeranol immobilized onto the electrode could result in great change in the electron-transfer resistance. Some factors that would affect the performance of the immunosensor were studied, such as concentration of PtCo, pH, and the ratio of TH to GS. With zeranol concentration range (0.05 to 5.0 ng/mL), the immunosensor exhibited a highly sensitive response to zeranol with a detection limit of 13 pg/mL. The immunosensor was evaluated for bovine urine sample, receiving satisfactory results. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Micro-flow Immunosensor Based on Thin-film Interdigitated Gold Array Microelectrodes for Cancer Biomarker Detection.

    PubMed

    Ravalli, Andrea; Lozzi, Luca; Marrazza, Giovanna

    2016-01-01

    In this paper, we reported the development of a micro-flow label-free impedimetric biosensor based on the use of thin-film interdigitated gold array microelectrodes (IDA) for the detection of carbohydrate antigen 125 (CA125). The immunosensor is developed through the electropolymerization of anthranilic acid (AA) on the surface of IDA electrodes followed by the covalent attachment of anti-CA125 monoclonal antibody. CA125 protein affinity reaction was then evaluated by means of electrochemical impedance spectroscopy (EIS). The sensor was characterized by electrochemical techniques and scanning electron microscopy (SEM). Using the optimized experimental conditions, the developed immunosensor showed a good analytical performance for CA125 detection from 0 to 100 U/mL with estimated limit of detection (LOD = 3Sblank/Slope) of 7 U/mL.

  19. Enzyme-linked immunosensor based on super paramagnetic nanobeads for easy and rapid detection of okadaic acid.

    PubMed

    Hayat, Akhtar; Barthelmebs, Lise; Marty, Jean-Louis

    2011-04-01

    Okadaic acid (OA), a lipophilic phycotoxin highly toxic to humans is produced by toxigenic dinoflagellates. The need to develop high performing methods for OA analysis able to improve the traditional ones is evident. In this work, competitive indirect enzyme-linked electrochemical immunosensor based on super paramagnetic nanobeads has been developed for the detection of OA. Streptavidin-coated magnetic beads were used as support to immobilize the biotinylated OA. Preliminary, colorimetric tests were performed in order to optimize different experimental parameters. Electrochemical detection was carried out by differential pulse voltammetry (DPV). The limit of detection (LOD) (0.38 μg L(-1)), the mid point value (IC(50)) (3.15 μg L(-1)) and the time needed (60 min) for analysis of a real sample validated the developed electrochemical immunosensor as a promising tool for routine use. The matrix effect and the recovery rate were also assessed, showing an excellent percentage of recovery.

  20. One-step immobilization of antibodies for α-1-fetoprotein immunosensor based on dialdehyde cellulose/ionic liquid composite.

    PubMed

    Shen, Guangyu; Zhang, Xiangyang; Shen, Youming; Zhang, Songbai; Fang, Li

    2015-02-15

    A novel immunosensor for α-1-fetoprotein based on dialdehyde cellulose/ionic liquid composite film as a matrix has been developed. Microcrystalline cellulose was activated by sodium metaperiodate to produce dialdehyde cellulose. Antibodies can be immobilized on the electrode by a one-step method through covalent bonding of the aldehyde groups of dialdehyde cellulose with the amino groups of antibodies, in which no additional chemical cross-linking step is required. Moreover, ionic liquid added can improve the conductivity of the sensing interface and, therefore, can enhance the electrochemical signal. In this work, α-1-fetoprotein was detected within the range from 0.1 to 60ngml(-1) with a detection limit of 0.07ngml(-1) (signal/noise=3). The proposed immunosensor had good specificity and reproducibility. It was used to determine real samples with satisfactory results. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. A carbon nanotube-based high-sensitivity electrochemical immunosensor for rapid and portable detection of clenbuterol.

    PubMed

    Liu, Gang; Chen, Haode; Peng, Hongzhen; Song, Shiping; Gao, Jimin; Lu, Jianxin; Ding, Min; Li, Lanying; Ren, Shuzhen; Zou, Ziying; Fan, Chunhai

    2011-10-15

    Carbon nanotubes have shown their unique advantages of mechanical, chemical and electronic properties in bioanalysis. We herein report a new method to efficiently and reproducibly prepare multi-walled carbon nanotubes (MWNTs)-protein sensing layers for electrochemical immunosensors. This method employs centrifugation to prepare a conjugate of MWNTs and goat anti mouse-immunoglobulin G (IgG) (secondary antibody). The conjugates were then deposited on screen-printed electrodes to form a nanostructured layer (MWNT-I layer). CLB monoclonal antibody was assembled through its binding to the secondary antibody. The MWNT-I layer-based electrodes were used for rapid and sensitive amperometric immunosensing detection of clenbuterol (CLB) in swine urine samples. Horseradish peroxidase-coupled CLB (CLB-HRP) competed with free CLB in the samples to bind the monoclonal antibody. It has shown significantly higher sensitivity and better reproducibility than the chemical conjugation method. This MWNT-based immunosensor is highly sensitive, leading to a limit of detection of 0.1 ng/mL within a rapid assay time of 16 min. Its sensitivity is at least 1 order of magnitude higher than that of a normal immunosensor (without MWNTs). The sensing device is portable with disposable screen-printed electrode, satisfactorily meeting the requirements for field detection of food security-related species.

  2. A sensitive label-free immunosensor for detection α-Fetoprotein in whole blood based on anticoagulating magnetic nanoparticles.

    PubMed

    Xu, Tingting; Chi, Bo; Wu, Fan; Ma, Shangshang; Zhan, Shuyue; Yi, Meihui; Xu, Hong; Mao, Chun

    2017-09-15

    Accurate values of tumor markers in blood play an especially important role in the diagnosis of illness. Here, based on the combination of three techniques include anticoagulant technology, nanotechnology and biosensing technology, a sensitive label-free immunosensor with anti-biofouling electrode for detection α-Fetoprotein (AFP) in whole blood was developed by anticoagulating magnetic nanoparticles. The obtained products of Fe3O4-ɛ-PL-Hep nanoparticles were characterized by fourier transform infrared (FT-IR) spectra, transmission electron microscopy (TEM), ζ-potential and vibrating sample magnetometry (VSM). Moreover, the blood compatibility of anticoagulating magnetic nanoparticles was characterized by in vitro coagulation tests, hemolysis assay and whole blood adhesion tests. Combining the anticoagulant property of heparin (Hep) and the good magnetism of Fe3O4, the Fe3O4-ɛ-PL-Hep nanoparticles could improve not only the anti-biofouling property of the electrode surface when they contact with whole blood, but also the stability and reproducibility of the proposed immunosensor. Thus, the prepared anticoagulating magnetic nanoparticles modified immunosensor for the detection of AFP showed excellent electrochemical properties with a wide concentration range from 0.1 to 100ng/mL and a low detection limit of 0.072ng/mL. Furthermore, five blood samples were assayed using the developed immunosensor. The results showed satisfactory accuracy with low relative errors. It indicated that our developed immunoassay was competitive and could be potentially used for the detection of whole blood samples directly. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. A Novel Controlled Release Immunosensor based on Benzimidazole Functionalized SiO2 and Cyclodextrin Functionalized Gold

    PubMed Central

    Ma, Hongmin; Wang, Yaoguang; Wu, Dan; Zhang, Yong; Gao, Jian; Ren, Xiang; Du, Bin; Wei, Qin

    2016-01-01

    A novel controlled release system-based sandwich-type immunosensor is fabricated to detect squamous cell carcinoma antigen (SCCA). The 1-methyl-1H-benzimidazole functionalized mesoporous SiO2 (MBI-MS) is used to load methylene blue (MB). β-cyclodextrin functionalized gold (CD-Au) is introduced as the gatekeeper for encapsulating MB and capturing the adamantly functional detection antibody (ADA-Ab2). And pH stimulus serves as the trigger system to control the MB release. After the load of MB, the CD-Au blocks the pores of the MBI-MS by the host-guest interaction in the neutral condition. However, when the pH is below 7.0, CD-Au is separated from the surface of MBI-MS owing to the protonation of the aromatic amines. The encapsulated MB is released from the pores of MBI-MS and detected by square wave voltammetry. The controlled release immunosensor shows a relatively wide linear range from 0.001 to 20 ng·mL−1 with a low detection limit of 0.25 pg·mL−1. The immunosensor also shows good reproducibility and selectivity, which endows it broad application prospect in clinical research. PMID:26791418

  4. A sandwich-type electrochemical immunosensor based on the biotin- streptavidin-biotin structure for detection of human immunoglobulin G

    PubMed Central

    Li, Yueyun; Zhang, Yihe; Jiang, Liping; Chu, Paul K.; Dong, Yunhui; Wei, Qin

    2016-01-01

    A sandwich-type immunosensor is designed and fabricated to detect the human immunoglobulin G (HIgG) using polyaniline and tin dioxide functionalized graphene (GS-SnO2-PAN) as the platform and biotin-functionalized amination magnetic nanoparticles composite (B-Fe3O4@APTES) as the label. GS-SnO2-PAN is used as the sensing agent to capture the primary anti-HIgG (Ab1) and SnO2 reduces the stack of GS. The B-Fe3O4@APTES with a large surface area and excellent biocompatibility captures second antibody (Ab2) efficiently based on the highly selective recognition of streptavidin to biotinylated antibody. The B-Fe3O4@APTES has better electro-catalytic activity in the reduction of hydrogen peroxide (H2O2) and the “biotin-streptavidin-biotin” (B-SA-B) strategy leads to signal amplification. Under optimal conditions, the immunosensor has a wide sensitivity range from 1 pg/L to 10 ng/L and low detection limit of 0.33 pg/L (S/N = 3) for HIgG. The immunosensor has high sensitivity, fast assay rate, as well as good reproducibility, specificity, and stability especially in the quantitative detection of biomolecules in serum samples. PMID:26948273

  5. Faraday cage-type electrochemiluminescence immunosensor for ultrasensitive detection of Vibrio vulnificus based on multi-functionalized graphene oxide.

    PubMed

    Guo, Zhiyong; Sha, Yuhong; Hu, Yufang; Yu, Zhongqing; Tao, Yingying; Wu, Yanjie; Zeng, Min; Wang, Sui; Li, Xing; Zhou, Jun; Su, Xiurong

    2016-10-01

    A novel Faraday cage-type electrochemiluminescence (ECL) immunosensor devoted to the detection of Vibrio vulnificus (VV) was fabricated. The sensing strategy was presented by a unique Faraday cage-type immunocomplex based on immunomagnetic beads (IMBs) and multi-functionalized graphene oxide (GO) labeled with (2,2'-bipyridine)(5-aminophenanthroline)ruthenium (Ru-NH2). The multi-functionalized GO could sit on the electrode surface directly due to the large surface area, abundant functional groups, and good electronic transport property. It ensures that more Ru-NH2 is entirely caged and become "effective," thus improving sensitivity significantly, which resembles extending the outer Helmholtz plane (OHP) of the electrode. Under optimal conditions, the developed immunosensor achieves a limit of detection as low as 1 CFU/mL. Additionally, the proposed immunosensor with high sensitivity and selectivity can be used for the detection of real samples. The novel Faraday cage-type method has shown potential application for the diagnosis of VV and opens up a new avenue in ECL immunoassay. Graphical abstract Faraday cage-type immunoassay mode for ultrasensitive detection by extending OHP.

  6. Detection of vibrio cholerae O1 by using cerium oxide nanowires - based immunosensor with different antibody immobilization methods

    NASA Astrophysics Data System (ADS)

    Tam, Phuong Dinh; Hoang, Nguyen Luong; Lan, Hoang; Vuong, Pham Hung; Anh, Ta Thi Nhat; Huy, Tran Quang; Thuy, Nguyen Thanh

    2016-05-01

    In this work, we evaluated the effects of different antibody immobilization strategies on the response of a CeO2-nanowires (NWs)-based immunosensor for Vibrio cholerae O1 detection. Accordingly, the changes in the electron-transfer resistance ( R et ) from before to after cells bind to an antibody-modified electrode prepared by using three different methods of antibody immobilization were determined. The values were 16.2%, 8.3%, and 6.65% for the method that utilized protein A, antibodies activated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS), and absorption, respectively. Cyclic voltammetry confirmed that the change in the current was highest for the immunosensors prepared using protein A (11%), followed by those prepared with EDC/NHS-activated antibodies (9%), and finally, those prepared through absorption (7.5%). The order of the antibody immobilization strategies in terms of resulting immunosensor detection limit and sensitivity was as follows order: absorption (3.2 × 103 CFU/mL; 45.1 Ω/CFU·mL-1) < EDC/NHS-activated antibody (1.0 × 103 CFU/mL; 50.6 Ω/CFU·mL-1) < protein A (1.0 × 102 CFU/mL; 65.8 Ω/CFU·mL-1). Thus, we confirmed that the protein A - mediated method showed significantly high cell binding efficiencies compared to the random immobilization method.

  7. A sensitive label–free amperometric immunosensor for alpha-fetoprotein based on gold nanorods with different aspect ratio

    PubMed Central

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

    2015-01-01

    A simple and accurate label–free amperometric immunosensor for α–fetoprotein (AFP) detection is developed based on gold nanorods (GNRs) with different aspect ratio and compared with gold particles (GNPs). The positively charged GNRs and GNPs due to the surface immobilized cetyltrimethyl ammonium bromide (CTAB) can adsorb the negatively charged AFP antibody (Ab) directly. The presence of the GNRs not only enhanced the immobilized amount of biomolecules, but also improved the electrochemical properties of the immunosensor. With the aid of GNRs, the electrochemical signal was greatly enhanced in comparison with GNPs. Under optimal conditions, the proposed immunosensor could detect AFP in a linear range from 0.1 to 200 ng/mL with a detection limit of 0.04 ng/mL (signal–to–noise ratio = 3), and it also possessed good reproducibility and storage stability. Moreover, the detection of AFP in five human serum samples also showed satisfactory accuracy. The proposed methodology was potentially attractive for clinical immunoassay. PMID:25909588

  8. A super intramolecular self-enhanced electrochemiluminescence immunosensor based on polymer chains grafted on palladium nanocages

    NASA Astrophysics Data System (ADS)

    Wang, Haijun; He, Ying; Chai, Yaqin; Yuan, Ruo

    2014-08-01

    An intramolecular self-enhanced electrochemiluminescent derivative is prepared by grafting polystyrene (PS)-based polymer chains with pendant Ru(ii) luminophore from poly(ethylenimine) (PEI) on the surface of palladium nanocages (PdNCs). In this way, the Ru(ii) luminophore and its co-reactive group (amine groups in PEI) exist in the same polymer molecule, which shortens the electronic transmission distance between them and enhances the luminous stability. Meanwhile, through atom transfer radical polymerization (ATRP), the loading amount of Ru(ii) luminophore is greatly increased. Therefore, the obtained electrochemiluminescent derivative (PdNC-PEI-PSRu) has high luminous efficiency and stability. Furthermore, due to their special nanostructures of porous walls and hollow interiors, PdNCs have great advantages in high specific surface areas and good electrocatalytic ability, which make them act as an excellent immobilized platform for PEI and detection antibody. Based on the sandwiched immunoreactions, a sensitive ``signal on'' electrochemiluminescence immunosensor is constructed for the detection of carbohydrate antigen 15-3 (CA 15-3). As a result, a wide linear range from 0.01 U mL-1 to 120 U mL-1 is acquired with a relatively low detection limit of 0.003 U mL-1.

  9. Portable surface plasmon resonance immunosensor for the detection of fluoroquinolone antibiotic residues in milk.

    PubMed

    Fernández, Fátima; Pinacho, Daniel G; Sánchez-Baeza, Francisco; Marco, M Pilar

    2011-05-11

    An inexpensive and portable surface plasmon resonance (SPR) sensor, SPReeta Evaluation Kit SPR3, has been used to develop a biosensor for the determination of fluoroquinolone antibiotics (FQs) and to demonstrate its performance analyzing FQ residues in milk samples. The SPReeta three-channel gold chips were activated with a mixed self-assembled monolayer (m-SAM) and functionalized with a FQ haptenized protein. Binding of the antibody produced a concentration-dependent increase of the SPR signal as a result of the change in the refraction index. Similarly, the presence of the FQ produced a dose-dependent decrease of the response, which allowed a good limit of detection (LOD) to be obtained (1.0 ± 0.4 μg L(-1) for enrofloxacin in buffer). The response was reproducible in all three channels, on different injections and days, and also between chips. Milk samples could be analyzed after a simple sample treatment involving fat removal by centrifugation and dilution with water. Under these conditions calibration curves were obtained showing that FQ residues can be analyzed in milk samples with an IC(50) value of 26.4 ± 7.2 μg L(-1) and a LOD of 2.0 ± 0.2 μg L(-1) (for enrofloxacin), far below the European Union regulations for this antibiotic family in this matrix. Finally, the paper also demonstrates that the biosensor is able to selectively detect the presence of FQs in milk samples, even in the presence of other antibiotics. Enrofloxacin, ciprofloxacin, and norfloxacin residues were detected in blind samples supplied by Nestlé Co.

  10. Thick-film electrochemical immunosensor based on stripping potentiometric detection of a metal ion label.

    PubMed

    Wang, J; Tian, B; Rogers, K R

    1998-05-01

    A disposable electrochemical immunosensor based on potentiometric stripping analysis (PSA) of a metal tracer and using an entirely on-chip assay format is demonstrated. Challenges associated with the adaptation of earlier stripping voltammetric immunoassays to an on-chip operation, and with meeting the demands of decentralized testing, have been addressed. These include the surface immobilization of the antibody, the replacement of mercury drop electrodes, elimination of the separation and oxygen-removal steps, and the use of quiescent 30-microL sample droplets. Human serum albumin (HSA) and anti-HSA antibody were used as a model system, while bismuth ion served as the metal label. The anti-HSA was immobilized onto the surface of a thick-film electrode, followed by a competition between the Bi-labeled analyte-tracer and the analyte (HSA) for the antibody binding sites. Upon removal of the unbound tracer, Bi3+ was released and detected by PSA. The dynamic concentration range for HSA (0.3-30 micrograms/mL) and the detection limit (0.2 microgram/mL, i.e., 90 fmol in the 30-microL sample) indicate that the greatly simplified protocol does not compromise the performance characteristics of stripping immunoassays. Consequently, this on-chip operation offers great promise for decentralized (clinical and environmental) applications.

  11. An automatic enzyme immunoassay based on a chemiluminescent lateral flow immunosensor.

    PubMed

    Joung, Hyou-Arm; Oh, Young Kyoung; Kim, Min-Gon

    2014-03-15

    Microfluidic integrated enzyme immunosorbent assay (EIA) sensors are efficient systems for point-of-care testing (POCT). However, such systems are not only relatively expensive but also require a complicated manufacturing process. Therefore, additional fluidic control systems are required for the implementation of EIAs in a lateral flow immunosensor (LFI) strip sensor. In this study, we describe a novel LFI for EIA, the use of which does not require additional steps such as mechanical fluidic control, washing, or injecting. The key concept relies on a delayed-release effect of chemiluminescence substrates (luminol enhancer and hydrogen peroxide generator) by an asymmetric polysulfone membrane (ASPM). When the ASPM was placed between the nitrocellulose (NC) membrane and the substrate pad, substrates encapsulated in the substrate pad were released after 5.3 ± 0.3 min. Using this delayed-release effect, we designed and implemented the chemiluminescent LFI-based automatic EIA system, which sequentially performed the immunoreaction, pH change, substrate release, hydrogen peroxide generation, and chemiluminescent reaction with only 1 sample injection. In a model study, implementation of the sensor was validated by measuring the high sensitivity C-reactive protein (hs-CRP) level in human serum.

  12. A polyaniline based ultrasensitive potentiometric immunosensor for cardiac troponin complex detection.

    PubMed

    Zhang, Qi; Prabhu, Alok; San, Avdar; Al-Sharab, Jafar F; Levon, Kalle

    2015-10-15

    An ultrasensitive immunosensor based on potentiometric ELISA for the detection of a cardiac biomarker, troponin I-T-C (Tn I-T-C) complex, was developed. The sensor fabrication involves typical sandwich ELISA procedures, while the final signal readout was achieved using open circuit potentiometry (OCP). Glassy carbon (GC) working electrodes were first coated with emulsion-polymerized polyaniline/dinonylnaphthalenesulfonic acid (PANI/DNNSA) and the coated surface was utilized as a transducer layer on which sandwich ELISA incubation steps were performed. An enzymatic reaction between o-phenylenediamine (OPD) and hydrogen peroxide (H2O2) was catalyzed by horseradish peroxidase (HRP) labeled on the secondary antibodies. The polymer transducer charged state was mediated through electron (e(-)) and charge transfers between the transducer and charged species generated by the same enzymatic reaction. Such a change in the polymer transducer led to potential variations against an Ag/AgCl reference electrode as a function of Tn I-T-C complex concentration during incubations. The sequence of OPD and H2O2 additions, electrochemical properties of the PANI/DNNSA layer and non-specific binding prevention were all crucial factors for the assay performance. Under optimized conditions, the assay has a low limit of detection (LOD) (< 5 pg/mL or 56 fM), a wide dynamic range (> 6 orders of magnitude), high repeatability (coefficient of variance < 8% for all concentrations higher than 5 pg/mL) and a short detection time (< 10 min).

  13. Measurement of polyphenol oxidase activity using optical waveguide lightmode spectroscopy-based immunosensor.

    PubMed

    Kim, Namsoo; Kim, Woo-Yeon

    2015-02-15

    Polyphenol oxidase (PPO) is an important quality index during food processing involving heat-treatment and sensitive determination of PPO activity has been a critical concern in the food industry. In this study, a new measurement of PPO activity exploiting an optical waveguide lightmode spectroscopy-based immunosensor is presented using a polyclonal anti-PPO antibody that was immobilized in situ to the surface of a 3-aminopropyltriethoxysilane-treated optical grating coupler activated with glutaraldehyde. When analysed with a purified PPO fraction from potato tubers, a linear relationship was found between PPO activities of 0.0005607-560.7U/mL and the sensor responses obtained. The sensor was applicable to measurement of PPO activity in real samples that were prepared from potato tubers, grapes and Kimchi cabbage, and the analytical results were compared with those obtained by a conventional colorimetric assay measuring PPO activity. When tested for long-term stability, the sensor was reusable up to 10th day after preparation.

  14. Plasma-enhanced antibody immobilization for the development of a capillary-based carcinoembryonic antigen immunosensor using laser-induced fluorescence spectroscopy.

    PubMed

    Yu, Qiaoling; Zhan, Xuefang; Liu, Kunping; Lv, Hao; Duan, Yixiang

    2013-05-07

    In this study, antibody immobilization using a microwave-induced H2O/Ar plasma pretreatment was achieved for the first time. Plasma was used to activate the surface of a capillary-based immunosensor by increasing the density of silicon hydroxyls and dangling bonds to ensure better silanization. The capture antibodies were covalently immobilized after the silanized surface reacted with glutaraldehyde and antibodies. A Cy3-labeled detection antibody was used in combination with the antigen captured by the immunosensor to complete the sandwich-type immunoassay, and the signals were measured using a laser-induced fluorescence system. Microwave-induced H2O/Ar plasma pretreatment of the carcinoembryonic antigen (CEA) immunosensor improved the antibody immobilization, and there was an obvious improvement in the linear detection range, i.e., 1 order of magnitude compared with a commercial enzyme-linked immunosorbent assay (ELISA). This novel immobilization method dramatically improved the detection limit (0.5 pmol/L CEA) and sensitivity. Assay validation studies indicated that the correlation coefficient reached 0.9978, and the relative standard deviations were <7% for all samples, with recoveries of 99.7-107.1%. Furthermore, the immunosensor was applied successfully to CEA determination in actual saliva specimens with high sensitivity, acceptable precision, and reasonable accuracy. This enhanced CEA immunosensor based on microwave-induced H2O/Ar plasma was demonstrated to be a sensitive tool for CEA diagnostics.

  15. A novel electrochemical immunosensor based on ITO modified by carboxyl-ended silane agent for ultrasensitive detection of MAGE-1 in human serum.

    PubMed

    Gündoğdu, Aslı; Aydın, Elif Burcu; Sezgintürk, Mustafa Kemal

    2017-09-12

    A new, low-cost electrochemical immunosensor was developed for rapid detection of Melanoma-associated antigen 1 (MAGE-1), a cancer biomarker. The fabrication procedure of immunosensor was based on the covalent immobilization of anti-MAGE-1, biorecognition molecule, on ITO electrode by carboxyethylsilanetriol (CTES) monolayer. The biosensing MAGE-1 antigen was monitored by using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) technique. Apart from these techniques, single frequency impedance (SFI) was used for investigation of antibody-antigen interactions. Scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) were utilized for characterization of the proposed biosensor. To fabricate highly sensitive, good stability immunosensor, some parameters were optimized. Under optimal conditions, the developed electrochemical immunosensor for MAGE-1 exhibited a dynamic range of 4 fg/mL and 200 fg/mL with a low detection limit of 1.30 fg/mL. It had acceptable repeatability (5.05%, n = 20) and good storage stability (3.58% loss after 10 weeks). Moreover, this electrochemical immunosensor has been successfully applied to the determination of MAGE-1 in human serum samples. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. An ultrasensitive electrochemical immunosensor for the detection of CD146 based on TiO2 colloidal sphere laden Au/Pd nanoparticles.

    PubMed

    Wang, Yaoguang; Li, Yueyun; Ma, Hongmin; Guo, Aiping; Du, Bin; Yan, Tao; Wei, Qin

    2015-05-21

    An ultrasensitive electrochemical immunosensor for the detection of cluster of differentiation 146 antigen (CD146) based on TiO2 colloidal sphere laden Au/Pd nanoparticles (Au/Pd@TiO2) was developed. In this work, reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) was applied as an electrode modifying material to modify the surface of a glassy carbon electrode (GCE). Au/Pd@TiO2 was used as the secondary-antibody (Ab2) label for the fabrication of the immunosensor. Amperometric response of the immunosensor for electrocatalytic reduction of hydrogen peroxide (H2O2) was recorded. Electrochemical impedance spectroscopy (EIS) proved that fabrication of the immunosensor was successful. The anti-CD146 primary antibody (Ab1) was immobilized on the rGO-TEPA modified GCE by a cross-linking reagent of glutaraldehyde (GA). With Ab1 immobilized onto the rGO-TEPA modified GCE and Ab2 linked with Au/Pd@TiO2, the immunosensor displayed a wide linear range (0.0050-20 ng mL(-1)), a low detection limit (1.6 pg mL(-1)), good reproducibility, good selectivity and acceptable stability. The designed sensing strategy may provide a potential application in the detection of other tumor markers.

  17. An electrochemical immunosensor for efficient detection of uropathogenic E. coli based on thionine dye immobilized chitosan/functionalized-MWCNT modified electrode.

    PubMed

    Gayathri, Chandran Hema; Mayuri, Pinapeddavari; Sankaran, Krishnan; Kumar, Annamalai Senthil

    2016-08-15

    Uropathogenic Escherichia coli (UPEC) is the major cause of 150 million Urinary Tract Infections (UTI) reported annually world-wide. High prevalence of multi-drug-resistance makes it dangerous and difficult to cure. Therefore simple, quick and early diagnostic tools are essential for effective treatment and control. We report an electrochemical immunosensor based on thionine dye (Th) immobilized on functionalized-multiwalled carbon nanotube+chitosan composite coated on glassy carbon electrode (GCE/f-MWCNT-Chit@Th) for quick and sensitive detection of UPEC in aqueous solution. This immunosensor was constructed by sequential immobilization of UPEC, bovine serum albumin, primary antibody and Horse Radish Peroxidase (HRP) tagged secondary antibody on the surface of GCE/f-MWCNT-Chit@Th. When analyzed using 2.5mM of hydrogen peroxide reduction reaction using cyclic voltammetry in phosphate buffer, pH 7.0, the immunosensor showed excellent linearity in a range of 10(2)-10(9)cfu of UPEC mL(-1) with a current sensitivity of 7.162μA {log(cfumL(-1))}(-1). The specificity of this immunosensor was tested using other UTI and non-UTI bacteria, Staphylococcus, Klebsiella, Proteus and Shigella. The clinical applicability of the immunosensor was also successfully tested directly in UPEC spiked urine samples (simulated sample). Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Sweet characterisation of prostate specific antigen using electrochemical lectin-based immunosensor assay and MALDI TOF/TOF analysis: Focus on sialic acid.

    PubMed

    Pihikova, Dominika; Pakanova, Zuzana; Nemcovic, Marek; Barath, Peter; Belicky, Stefan; Bertok, Tomas; Kasak, Peter; Mucha, Jan; Tkac, Jan

    2016-12-01

    The construction of a sensitive electrochemical lectin-based immunosensor for detection of a prostate specific antigen (PSA) is shown here. Three lectins with different carbohydrate specificities were used in this study to glycoprofile PSA, which is the most common biomarker for prostate cancer (PCa) diagnosis. The biosensor showed presence of α-L-fucose and α-(2,6)-linked terminal sialic acid within PSA´s glycan with high abundance, while only traces of α-(2,3)-linked terminal sialic acid were found. MALDI TOF/TOF mass spectrometry was applied to validate results obtained by the biosensor with a focus on determination of a type of sialic acid linkage by two methods. The first direct comparison of electrochemical immunosensor assay employing lectins for PSA glycoprofiling with mass spectrometric techniques is provided here and both methods show significant agreement. Thus, electrochemical lectin-based immunosensor has potential to be applied for prostate cancer diagnosis.

  19. Field-Based Detection and Mnitoring of Uranium in Contaminated Groundwater using two Immunosensors

    SciTech Connect

    Melton, Scott J; Yu, Haini; Williams, Kenneth H; Morris, Sarah A; Long, Philip E; Blake, Diane A

    2009-09-01

    Field-based monitoring of environmental contaminants has long been a need for environmental scientists. Described herein are two kinetic exclusion-based immunosensors, a field portable sensor (FPS) and an inline senor, that were deployed at the Integrated Field Research Challenge Site of the U.S. Department of Energy in Rifle, CO. Both sensors utilized a monoclonal antibody that binds to a U(VI)-dicarboxyphenanthroline complex (DCP) in a kinetic exclusion immunoassay format. These sensors were able to monitor changes of uranium in groundwater samples from ~1 μM to below the regulated drinking water limit of 126 nM (30 ppb). The FPS is a battery-operated sensor platform that can determine the uranium level in a single sample in 5-10 min, if the instrument has been previously calibrated with standards. The average minimum detection level (MDL) in this assay was 0.33 nM (79 ppt), and the MDL in the sample (based on a 1:200-1:400 dilution) was 66-132 nM (15.7-31.4 ppb). The inline sensor, while requiring a grounded power source, has the ability to autonomously analyze multiple samples in a single experiment. The average MDL in this assay was 0.12 nM (29 ppt), and the MDL in the samples (based on 1:200 or 1:400 dilutions) was 24-48 nM (5.7-11.4 ppb). Both sensor platforms showed an acceptable level of agreement (r2 = 0.94 and 0.76, for the inline and FPS, respectively) with conventional methods for uranium quantification.

  20. Field-based detection and monitoring of uranium in contaminated groundwater using two immunosensors

    SciTech Connect

    Melton, S.J.; Yu, H.; Williams, K.H.; Morris, S.A.; Long, P.E.; Blake, D.A.

    2009-05-01

    Field-based monitoring of environmental contaminants has long been a need for environmental scientists. Described herein are two kinetic exclusion-based immunosensors, a field portable sensor (FPS) and an inline senor, that were deployed at the Integrated Field Research Challenge Site of the U.S. Department of Energy in Rifle, CO. Both sensors utilized a monoclonal antibody that binds to a U(VI)-dicarboxyphenanthroline complex (DCP) in a kinetic exclusion immunoassay format. These sensors were able to monitor changes of uranium in groundwater samples from {approx} 1 {micro}M to below the regulated drinking water limit of 126 nM (30 ppb). The FPS is a battery-operated sensor platform that can determine the uranium level in a single sample in 5-10 min, if the instrument has been previously calibrated with standards. The average minimum detection level (MDL) in this assay was 0.33 nM (79 ppt), and the MDL in the sample (based on a 1:200?1:400 dilution) was 66?132 nM (15.7?31.4 ppb). The inline sensor, while requiring a grounded power source, has the ability to autonomously analyze multiple samples in a single experiment. The average MDL in this assay was 0.12 nM (29 ppt), and the MDL in the samples (based on 1:200 or 1:400 dilutions) was 24?48 nM (5.7?11.4 ppb). Both sensor platforms showed an acceptable level of agreement (r{sup 2} = 0.94 and 0.76, for the inline and FPS, respectively) with conventional methods for uranium quantification.

  1. Metal ions-based immunosensor for simultaneous determination of estradiol and diethylstilbestrol.

    PubMed

    Zhang, Sen; Du, Bin; Li, He; Xin, Xiaodong; Ma, Hongmin; Wu, Dan; Yan, Liangguo; Wei, Qin

    2014-02-15

    Environmental estrogens (EEs) can cause various endocrine diseases. Herein, we designed an ultrasensitive electrochemical immunosensor for simultaneous detection of two typical EEs, estradiol and diethylstilbestrol. These two analytes were immobilized on graphene sheet (GS) modified glassy carbon electrode (GCE). Amino-group functionalized mesoporous Fe3O4 (Fe3O4-NH2) was loaded with Pb(2+) or Cd(2+), and then incubated with estradiol and diethylstilbestrol antibodies, respectively. Using an electrochemical analysis technique, two well-separated peaks were generated by the redox reaction of Pb(2+) or Cd(2+), making the simultaneous detection of two analytes on the electrode possible. Subsequently, square wave anodic stripping voltammetry (SWASV) and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical behaviors of the immunosensor. Under optimized conditions, the SWASV peak currents were proportional to the concentrations of estradiol and diethylstilbestrol in the range from 0.050 pg mL(-1) to 100 ng mL(-1) and 1.0 pg mL(-1) to 100 ng mL(-1), respectively. The immunosensor exhibited highly sensitive response to estradiol with a detection limit of 0.015 pg mL(-1) and diethylstilbestrol with a detection limit of 0.38 pg mL(-1). Furthermore, the immunosensor was satisfactorily employed to detect estradiol and diethylstilbestrol simultaneously in water samples.

  2. An Electrochemiluminescence Immunosensor Based on Gold-Magnetic Nanoparticles and Phage Displayed Antibodies

    PubMed Central

    Mu, Xihui; Tong, Zhaoyang; Huang, Qibin; Liu, Bing; Liu, Zhiwei; Hao, Lanqun; Dong, Hua; Zhang, Jinping; Gao, Chuan

    2016-01-01

    Using the multiple advantages of the ultra-highly sensitive electrochemiluminescence (ECL) technique, Staphylococcus protein A (SPA) functionalized gold-magnetic nanoparticles and phage displayed antibodies, and using gold-magnetic nanoparticles coated with SPA and coupled with a polyclonal antibody (pcAb) as magnetic capturing probes, and Ru(bpy)32+-labeled phage displayed antibody as a specific luminescence probe, this study reports a new way to detect ricin with a highly sensitive and specific ECL immunosensor and amplify specific detection signals. The linear detection range of the sensor was 0.0001~200 µg/L, and the limit of detection (LOD) was 0.0001 µg/L, which is 2500-fold lower than that of the conventional ELISA technique. The gold-magnetic nanoparticles, SPA and Ru(bpy)32+-labeled phage displayed antibody displayed different amplifying effects in the ECL immunosensor and can decrease LOD 3-fold, 3-fold and 20-fold, respectively, compared with the ECL immunosensors without one of the three effects. The integrated amplifying effect can decrease the LOD 180-fold. The immunosensor integrates the unique advantages of SPA-coated gold-magnetic nanoparticles that improve the activity of the functionalized capturing probe, and the amplifying effect of the Ru(bpy)32+-labeled phage displayed antibodies, so it increases specificity, interference-resistance and decreases LOD. It is proven to be well suited for the analysis of trace amounts of ricin in various environmental samples with high recovery ratios and reproducibility. PMID:26927130

  3. An Electrochemiluminescence Immunosensor Based on Gold-Magnetic Nanoparticles and Phage Displayed Antibodies.

    PubMed

    Mu, Xihui; Tong, Zhaoyang; Huang, Qibin; Liu, Bing; Liu, Zhiwei; Hao, Lanqun; Dong, Hua; Zhang, Jinping; Gao, Chuan

    2016-02-27

    Using the multiple advantages of the ultra-highly sensitive electrochemiluminescence (ECL) technique, Staphylococcus protein A (SPA) functionalized gold-magnetic nanoparticles and phage displayed antibodies, and using gold-magnetic nanoparticles coated with SPA and coupled with a polyclonal antibody (pcAb) as magnetic capturing probes, and Ru(bpy)₃(2+)-labeled phage displayed antibody as a specific luminescence probe, this study reports a new way to detect ricin with a highly sensitive and specific ECL immunosensor and amplify specific detection signals. The linear detection range of the sensor was 0.0001~200 µg/L, and the limit of detection (LOD) was 0.0001 µg/L, which is 2500-fold lower than that of the conventional ELISA technique. The gold-magnetic nanoparticles, SPA and Ru(bpy)₃(2+)-labeled phage displayed antibody displayed different amplifying effects in the ECL immunosensor and can decrease LOD 3-fold, 3-fold and 20-fold, respectively, compared with the ECL immunosensors without one of the three effects. The integrated amplifying effect can decrease the LOD 180-fold. The immunosensor integrates the unique advantages of SPA-coated gold-magnetic nanoparticles that improve the activity of the functionalized capturing probe, and the amplifying effect of the Ru(bpy)₃(2+)-labeled phage displayed antibodies, so it increases specificity, interference-resistance and decreases LOD. It is proven to be well suited for the analysis of trace amounts of ricin in various environmental samples with high recovery ratios and reproducibility.

  4. Gold nanoparticle-based enhanced chemiluminescence immunosensor for detection of Staphylococcal Enterotoxin B (SEB) in food

    PubMed Central

    Yang, Minghui; Kostov, Yordan; Bruck, Hugh A.; Rasooly, Avraham

    2010-01-01

    Staphylococcal enterotoxins (SEs) are major cause of foodborne diseases, so sensitive detection (<1 ng/ml) methods are needed for SE detection in food. The surface area, geometric and physical properties of gold nanoparticles make them well-suited for enhancing interactions with biological molecules in assays. To take advantage of the properties of gold nanoparticles for immunodetection, we have developed a gold nanoparticle-based enhanced chemiluminescence (ECL) immunosensor for detection of Staphylococcal Enterotoxin B (SEB) in food. Anti-SEB primary antibodies were immobilized onto a gold nanoparticle surface through physical adsorption and then the antibody–gold nanoparticle mixture was immobilized onto a polycarbonate surface. SEB was detected by a “sandwich-type” ELISA assay on the polycarbonate surface with a secondary antibody and ECL detection. The signal from ECL was read using a point-of-care detector based on a cooled charge-coupled device (CCD) sensor or a plate reader. The system was used to test for SEB in buffer and various foods (mushrooms, tomatoes, and baby food meat). The limit of detection was found to be ~0.01 ng/mL, which is ~10 times more sensitive than traditional ELISA. The gold nanoparticles were relatively easy to use for antibody immobilization because of their physical adsorption mechanism; no other reagents were required for immobilization. The use of our simple and inexpensive detector combined with the gold nanoparticle-based ECL method described here is adaptable to simplify and increase sensitivity of any immunological assay and for point-of-care diagnostics. PMID:19540011

  5. Quinone-Based Polymers for Label-Free and Reagentless Electrochemical Immunosensors: Application to Proteins, Antibodies and Pesticides Detection

    PubMed Central

    Piro, Benoit; Reisberg, Steeve; Anquetin, Guillaume; Duc, Huynh-Thien; Pham, Minh-Chau

    2013-01-01

    Polyquinone derivatives are widely recognized in the literature for their remarkable properties, their biocompatibility, simple synthesis, and easy bio-functionalization. We have shown that polyquinones present very stable electroactivity in neutral aqueous medium within the cathodic potential domain avoiding side oxidation of interfering species. Besides, they can act as immobilized redox transducers for probing biomolecular interactions in sensors. Our group has been working on devices based on such modified electrodes with a view to applications for proteins, antibodies and organic pollutants using a reagentless label-free electrochemical immunosensor format. Herein, these developments are briefly reviewed and put into perspective. PMID:25587398

  6. Development of an immunosensor using oriented immobilized anti-OmpW for sensitive detection of Vibrio cholerae by surface plasmon resonance.

    PubMed

    Taheri, Ramezan Ali; Rezayan, Ali Hossein; Rahimi, Fereshteh; Mohammadnejad, Javad; Kamali, Mehdi

    2016-12-15

    The first SPR sensor for detection of bacteria was reported in 1998 with high detection limit as much as 10(7)cfu/mL. Since then, a lot of effort has been made to lower detection limit and increase sensitivity of detection mainly by using of different assay formats, immobilization strategies, suitable antibodies, minimizing non-specific adsorption and improving the quality of SPR devices. The aim of this paper is to introduce the potential of an antibody against recombinant outer membrane protein (anti-OmpW) in sensitive detection of Vibrio cholerae by developing an immunosensor based on SPR and compare the sensitivity of this method with former report for detection of V. cholerae published in 2006. Recombinant OmpW antigen (a bacterial outer-membrane protein) of V. cholerae was expressed and purified and raising of polyclonal rabbit anti-OmpW was done. Protein G was covalently immobilized on 11-MUA SAM via amine coupling and bioaffinity-based oriented immobilization of anti-OmpW was done on protein G layer. The results showed high affinity interaction between OmpW and anti-OmpW (KD=2.4×10(-9)M) and the detection limit of fabricated immunosensor was 43 cells/mL. The apparent reasons for achieving this low LOD are discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. A novel sandwich electrochemiluminescence immunosensor for ultrasensitive detection of carbohydrate antigen 19-9 based on immobilizing luminol on Ag@BSA core/shell microspheres.

    PubMed

    Zhang, Amin; Xiang, Hongkun; Zhang, Xin; Guo, Weiwei; Yuan, Enhui; Huang, Chusen; Jia, Nengqin

    2016-01-15

    A novel sandwich-type electrochemiluminescence immunosensor based on immobilizing luminol on Ag@BSA core/shell microspheres (Ag@BSA-luminol) for ultrasensitive detection of tumor marker carbohydrate antigen 19-9 (CA19-9) has been developed. Herein, magnetic carbon nanotubes (MAGCNTs) decorated with polyethylenimine (PEI) was used to construct the base of the immunosensor. MAGCNTs with prominent electrical conductivity and high surface area could be beneficial for promoting the electron transfer and loading plenty of primary antibodies (Ab1) via glutaraldehyde (GA). Meanwhile, the magnetic property of MAGCNTs makes it easy to be attached to the surface of magnetic glass carbon electrode (MGCE) through magnetism interaction, which provides an outstanding platform for this immunosensor. Moreover, Ag@BSA microspheres with large surface area, good stability, and excellent biocompatibility were desirable candidates for effective cross-link of CA19-9 detection antibodies (Ab2). A more interesting thing was that ELISA color reaction was used as an ultrasensitive strategy for identifying Ab2 was successfully coated on Ag@BSA with the naked eye. Additionally, we immobilized the luminol on the surface of Ag@BSA to prepare the target immunosensor. Immobilization of luminol on the surface of Ag@BSA could decrease the distance between luminophores and the electrode surface, leading to great enhancement of the ECL intensity of luminol in the present of hydrogen peroxide (H2O2). Under the optimal conditions, the intensity of the ECL immunosensor increased linearly with the logarithm of CA19-9 concentration in a wide linear range from 0.0005 to 150UmL(-1) with a detection limit of 0.0002UmL(-1) (S/N=3). All the results suggested the prepared CA19-9 immunosensor displayed high sensitivity, excellent stability and good specificity. The developed method opened a new avenue to clinical bioassay. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Gold nanoparticle-based localized surface plasmon immunosensor for staphylococcal enterotoxin A (SEA) detection.

    PubMed

    Ben Haddada, Maroua; Hu, David; Salmain, Michèle; Zhang, Lu; Peng, Chen; Wang, Yi; Liedberg, Bo; Boujday, Souhir

    2017-08-16

    We describe the engineering of stable gold nanoparticle (AuNP) bioconjugates for the detection of staphylococcal enterotoxin A (SEA) using localized surface plasmon resonance (LSPR). Two types of AuNP bioconjugates were prepared by covalently attaching anti-SEA antibody (Ab) or SEA to AuNPs. This was achieved by reacting Traut's reagent with lysine residues of both proteins to generate thiol groups that bind to gold atoms on the AuNP surface. These bioconjugates were characterized in-depth by absorption spectroscopy, cryo-transmission electron microscopy, dynamic light scattering, and zeta potential measurements. Their stability over time was assessed after 1 year storage in the refrigerator at 4 °C. Two formats of homogeneous binding assays were set up on the basis of monitoring of LSPR peak shifts resulting from the immunological reaction between the (i) immobilized antibody and free SEA, the direct assay, or (ii) immobilized SEA and free antibody, the competitive assay. In both formats, a correlation between the LSPR band shift and SEA concentration could be established. Though the competitive format did not meet the expected analytical performance, the direct format, the implementation of which was very simple, afforded a specific and sensitive response within a broad dynamic range-nanogram per milliliter to microgram per milliliter. The limit of detection (LOD) of SEA was estimated to equal 5 ng/mL, which was substantially lower than the LOD obtained using a quartz crystal microbalance. Moreover, the analytical performance of AuNP-Ab bioconjugate was preserved after 1 year of storage at 4 °C. Finally, the LSPR biosensor was successfully applied to the detection of SEA in milk samples. The homogeneous nanoplasmonic immunosensor described herein provides an attractive alternative for stable and reliable detection of SEA in the nanogram per milliliter range and offers a promising avenue for rapid, easy to implement, and sensitive biotoxin detection

  9. A gas-phase amplified quartz crystal microbalance immunosensor based on catalase modified immunoparticles.

    PubMed

    Liu, Wei; Huang, Renliang; Qi, Wei; Wang, Mengfan; Su, Rongxin; He, Zhimin

    2015-02-21

    A novel signal amplification strategy for quartz crystal microbalance (QCM) based on catalytic gas generation was developed to construct an ultrasensitive immunosensor for the detection of proteins (immunoglobulin G, IgG, used as a model). A catalase modified immunoparticle was prepared to form a sandwich-type immunocomplex with the IgG and anti-IgG antibodies that were immobilized on the QCM sensor. The amount of immunoparticles on the sensor surface was thus controlled by the IgG concentration. Then H2O2 was added and catalyzed by catalase for oxygen generation. The generated oxygen replaced some of the liquid on the sensor surface, leading to the change in the shear modulus of the immunocomplex layer and the apparent viscosity and density of the liquid layer. Due to the ultrasensitive response of QCM to these changes, a significant frequency shift related to the IgG concentration was achieved. Different parameters, including the flow cell structure, operation temperature, immunoparticle concentration, and H2O2 concentration were optimized to achieve steady and efficient frequency shifts. Under the optimal conditions, the proposed gas-phase amplified QCM sensor could achieve up to 72 times improvement of detection sensitivity compared to the label-free sensor as a control, in the concentration range of 0.1-3.0 μg mL(-1). The detection limit was also reduced from 236 ng mL(-1) to 51.0 ng mL(-1) at the 3Sblank level.

  10. Self-powered competitive immunosensor driven by biofuel cell based on hollow-channel paper analytical devices.

    PubMed

    Li, Shuai; Wang, Yanhu; Ge, Shenguang; Yu, Jinghua; Yan, Mei

    2015-09-15

    A mediator-less and compartment-less glucose/O2 enzymatic biofuel cell (BFC) was introduced into microfluidic paper-based analytical devices (μ-PADs) that relies on flow in hollow channels with silver nanoparticles/graphene modified paper electrode as the anodic and cathodic substrate, to implement self-powered sensitive carcinoembryonic antigen (CEA) detection. Glucose dehydrogenase (GDH)-gold nanoparticles bioconjugate modified with CEA acted as a biocatalyst for enhancing glucose oxidation in the bioanode, as well as the transducing enzyme for signaling magnification. Similarly, nanoporous PtNi/bilirubin oxidase (BOD) acted as a biocatalyst for enhancing O2 reduction in the biocathode. With an increase in the concentration of CEA, the amount of CEA-Au-GDH bioconjugate on bioanode decreases, thus leading to the lower output of the as-prepared BFC. This proposed BFC-based self-powered immunosensor for CEA possessed largely increased linear detection range from 1 pg mL(-1) to 0.5 μg mL(-)(1) with a detection limit of 0.7 pg mL(-)(1). The proposed BFC-based self-powered immunosensor shows high sensitivity, stability, and reproducibility and can become a promising platform for other protein detection. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. An impedimetric immunosensor based on diamond nanowires decorated with nickel nanoparticles.

    PubMed

    Subramanian, Palaniappan; Motorina, Anastasiia; Yeap, Weng Siang; Haenen, Ken; Coffinier, Yannick; Zaitsev, Vladimir; Niedziolka-Jonsson, Joanna; Boukherroub, Rabah; Szunerits, Sabine

    2014-04-07

    Nanostructured boron-doped diamond has been investigated as a sensitive impedimetric electrode for the detection of immunoglobulin G (IgG). The immunosensor was constructed in a three-step process: (i) reactive ion etching of flat boron-doped diamond (BDD) interfaces to synthesize BDD nanowires (BDD NWs), (ii) electrochemical deposition of nickel nanoparticles (Ni NPs) on the BDD NWs, and (iii) immobilization of biotin-tagged anti-IgG onto the Ni NPs. Electrochemical impedance spectroscopy (EIS) was used to follow the binding of IgG at different concentrations without the use of any additional label. A detection limit of 0.3 ng mL(-1) (2 nM) with a dynamic range up to 300 ng mL(-1) (2 μM) was obtained with the interface. Moreover, the study demonstrated that this immunosensor exhibits good stability over time and allows regeneration by incubation in ethylenediaminetetraacetic acid (EDTA) aqueous solution.

  12. Detection of parasite antigens in Leishmania infantum-infected spleen tissue by monoclonal antibody-, piezoelectric-based immunosensors.

    PubMed

    Cabral-Miranda, G; de Jesus, J R; Oliveira, P R S; Britto, G S G; Pontes-de-Carvalho, L C; Dutra, R F; Alcântara-Neves, N M

    2014-02-01

    Diseases such as leishmaniases are important causes of morbidity and mortality in Brazil, and their diagnoses need to be improved. The use of monoclonal antibodies has ensured high specificity to immunodiagnosis. The development of an immunosensor, coupling a monoclonal antibody to a bioelectronic device capable of quickly detecting Leishmania sp. antigens both qualitatively and quantitatively, is a promising alternative for the diagnosis of leishmaniasis due to its high specificity, low cost, and portability, compared with conventional methods. The present work was aimed at developing an immunosensor-based assay for detecting Leishmania infantum antigens in tissues of infected hosts. Four hybridomas producing monoclonal antibodies against L. infantum had their specificity confirmed by enzyme-linked immunosorbent assay. These antibodies were immobilized on a gold surface, covered with a thin film of 2-aminoethanethiol (cysteamine) and glutaraldehyde, blocked with glycine, and placed into contact with extracts of L. infantum -infected and noninfected control hamster spleens. The assay was able to detect 1.8 × 10(4) amastigotes/g of infected tissue. These results demonstrated that this assay may be useful for quantifying L. infantum amastigotes in organs of experimental animals for studies on pathogenesis and immunity and that it is a promising tool for the development of a diagnostic method, based on antigen detection, of human and dog visceral leishmaniasis.

  13. An Elegant Analysis of White Spot Syndrome Virus Using a Graphene Oxide/Methylene Blue based Electrochemical Immunosensor Platform

    NASA Astrophysics Data System (ADS)

    Natarajan, Anusha; Devi, K. S. Shalini; Raja, Sudhakaran; Senthil Kumar, Annamalai

    2017-04-01

    White spot syndrome virus (WSSV) is a major devastating virus in aquaculture industry. A sensitive and selective diagnostic method for WSSV is a pressing need for the early detection and protection of the aquaculture farms. Herein, we first report, a simple electrochemical immunosensor based on methylene blue dye (MB) immobilized graphene oxide modified glassy carbon electrode (GCE/GO@MB) for selective, quick (35 ± 5 mins) and raw sample analysis of WSSV. The immunosensor was prepared by sequential modification of primary antibody, blocking agent (bovine serum album), antigen (as vp28 protein), secondary antibody coupled with horseradish peroxidase (Ab2-HRP) on the GCE/GO@MB. The modified electrode showed a well-defined redox peak at an equilibrium potential (E1/2), -0.4 V vs Ag/AgCl and mediated H2O2 reduction reaction without any false positive result and dissolved oxygen interferences in pH 7 phosphate buffer solution. Under an optimal condition, constructed calibration plot was linear in a range of 1.36 × 10-3 to 1.36 × 107 copies μL-1 of vp28. It is about four orders higher sensitive than that of the values observed with polymerase chain reaction (PCR) and western blot based WSSV detection techniques. Direct electrochemical immunosensing of WSSV in raw tissue samples were successfully demonstrated as a real sample system.

  14. An Elegant Analysis of White Spot Syndrome Virus Using a Graphene Oxide/Methylene Blue based Electrochemical Immunosensor Platform

    PubMed Central

    Natarajan, Anusha; Devi, K. S. Shalini; Raja, Sudhakaran; Senthil Kumar, Annamalai

    2017-01-01

    White spot syndrome virus (WSSV) is a major devastating virus in aquaculture industry. A sensitive and selective diagnostic method for WSSV is a pressing need for the early detection and protection of the aquaculture farms. Herein, we first report, a simple electrochemical immunosensor based on methylene blue dye (MB) immobilized graphene oxide modified glassy carbon electrode (GCE/GO@MB) for selective, quick (35 ± 5 mins) and raw sample analysis of WSSV. The immunosensor was prepared by sequential modification of primary antibody, blocking agent (bovine serum album), antigen (as vp28 protein), secondary antibody coupled with horseradish peroxidase (Ab2-HRP) on the GCE/GO@MB. The modified electrode showed a well-defined redox peak at an equilibrium potential (E1/2), −0.4 V vs Ag/AgCl and mediated H2O2 reduction reaction without any false positive result and dissolved oxygen interferences in pH 7 phosphate buffer solution. Under an optimal condition, constructed calibration plot was linear in a range of 1.36 × 10−3 to 1.36 × 107 copies μL−1 of vp28. It is about four orders higher sensitive than that of the values observed with polymerase chain reaction (PCR) and western blot based WSSV detection techniques. Direct electrochemical immunosensing of WSSV in raw tissue samples were successfully demonstrated as a real sample system. PMID:28393929

  15. Novel surface antigen based impedimetric immunosensor for detection of Salmonella typhimurium in water and juice samples.

    PubMed

    Mutreja, Ruchi; Jariyal, Monu; Pathania, Preeti; Sharma, Arunima; Sahoo, D K; Suri, C Raman

    2016-11-15

    A specific surface antigen, OmpD has been reported first time as a surface biomarker in the development of selective and sensitive immunosensor for detecting Salmonella typhimurium species. The OmpD surface antigen extraction was done from Salmonella typhimurium serovars, under the optimized growth conditions for its expression. Anti-OmpD antibodies were generated and used as detector probe in immunoassay format on graphene-graphene oxide (G-GO) modified screen printed carbon electrodes. The water samples were spiked with standard Salmonella typhimurium cells, and detection was done by measuring the change in impedimetric response of developed immunosensor to know the concentration of serovar Salmonella typhimurium. The developed immunosensor was able to specifically detect S. typhimurium in spiked water and juice samples with a sensitivity upto 10(1)CFUmL(-1), with high selectivity and very low cross-reactivity with other strains. This is the first report on the detection of Salmonella typhimurum species using a specific biomarker, OmpD. The developed technique could be very useful for the detection of nontyphoidal Salmonellosis and is also important from an epidemiological point of view.

  16. Monitoring microbial populations of sulfate-reducing bacteria using an impedimetric immunosensor based on agglutination assay.

    PubMed

    Wan, Yi; Zhang, Dun; Hou, Baorong

    2009-11-15

    An impedimetric immunosensor was fabricated for rapid and non-labeled detection of sulfate-reducing bacteria, Desulforibrio caledoiensis (SRB) by immobilizing lectin-Concanavalin A using an agglutination assay. The immobilization of lectin was conducted using amine coupling on the surface of a gold (Au) electrode assembled with 11-Mercaptoundecanoic acid. Electrochemical impedance spectroscopy (EIS) was used to verify the stepwise assembly of the sensor system. The work conditions of the impedimetric immunosensor, such as pH of the buffer solutions and the incubation time of lectin, were optimized. Faradic impedance spectra for charge transfer for the redox probe Fe(CN)(6)(3-/4-)were measured to determine SRB concentrations. The diameter of the Nyquist diagram that is equal to the charge-transfer resistance (R(ct)) increased with increasing SRB concentration. A linear relationship between R(ct) and SRB concentration was obtained in SRB concentration range of 1.8 to 1.8 x 10(7)cfu/ml. The variation of the SRB population during the growth process was also monitored using the impedimetric immunosensor. This approach has great potential for simple, low-cost, and time-saving monitoring of microbial populations.

  17. Construction and biomedical application of immunosensors based on fiber optics and enhanced chemiluminescence

    NASA Astrophysics Data System (ADS)

    Starodub, Nicolaj F.; Arenkov, Pavel Y.; Starodub, Alexander N.; Berezin, Vladimir A.

    1994-09-01

    The main scheme of the measuring cell as well as the sensor device, the analysis conditions, and the results of the quantitative determination of several antigens are presented. Special attention is paid to the immobilization of one of the immunocomponents on the fiber optic surface and three approaches were investigated: (1) covalent binding of the immunocomponent with the help of glutaraldehyde to the surface preliminary treated by aminopropilethoxysalane, (2) direct binding of the immunocomponent to silicon oxide surface by BrCN, and (3) usage of a special membrane closely connected to the fiber optics. The investigation showed that the level of immobilized biomolecules may be achieved almost two fold more by the second approach in comparison with the first one. Good results can also be received by the usage of the special membrane. The sensitivity of the fiber optic immunosensors intended for the determination of the antigens selected was comparable with that made by the enzyme-linked immunosorbent assay (ELISA) method. But in all cases the rate of analyses by immunosensors was much higher than that of the ELISA method, which is the main advantage of such types of immunosensors.

  18. Signal-amplified platform for electrochemical immunosensor based on TiO2 nanotube arrays using a HRP tagged antibody-Au nanoparticles as probe.

    PubMed

    Gao, Zhi-Da; Guan, Fang-Fang; Li, Cheng-Yong; Liu, Hai-Feng; Song, Yan-Yan

    2013-03-15

    In this study, a novel signal-amplified electrochemical immunosensor was proposed by using TiO(2) nanotube (TiNT) arrays as the platform. Due to the distinct tubular features-large surface area, high pore volume and good electrochemical conductivity, the TiNT based electrodes exhibited excellent signal-amplified effects. gold nanoparticle (AuNP) was further utilized to bind horseradish peroxidase (HRP) tagged antibodies as recognition elements. Compared to the immunosensor based on either flat electrode, the immunosensors using TiNT layer as electrode showed higher amplified electrochemical signals from the catalytic reaction of HRP relative to hydrogen peroxide (H(2)O(2)). Under optimal conditions, the proposed immunosensor exhibited a good electrochemical behavior to antigen in a concentration range from 0.1 ng mL(-1) to 10(5) ng mL(-1) with a detection limit of 0.01 ng mL(-1). The results showed that the TiNT-based electrochemical immunosensing platform could provide a great potential in clinical application for detection of low-abundant proteins.

  19. Dual immunosensor based on methylene blue-electroadsorbed graphene oxide for rapid detection of the influenza A virus antigen.

    PubMed

    Veerapandian, Murugan; Hunter, Robert; Neethirajan, Suresh

    2016-08-01

    Rapid detection of influenza viral infections in poultry facilities is advantageous in several aspects such as environmental/personal safety, food-security, and socio-economy. Herein, we report the development of an electrochemical-based dual-sensor platform composed of methylene blue-electroadsorbed graphene oxide nanostructures modified with monoclonal antibodies against the HA proteins of H5N1 and H1N1. Bio-functional layers comprised of chitosan and protein-A molecules were implemented at the interface of the sensor element and antibodies, which synergistically enriched the bio-activity of immobilized antibodies for the immune complex formation. The differential pulse voltammetric signals resulted from the developed immunosensor platform exhibited a good correlation (R(2)=0.9978 for H1N1 and R(2)=0.9997 for H5N1) for the wide range of target concentrations 25-500pM). Chronoamperometric study also revealed the amplified current sensitivity of the immunoelectrodes even at the picomolar level. The proposed immunosensor design not only provides rapid analytical response time (<1min) but simplicity in fabrication and instrumentation, which paves an attractive platform for on-farm monitoring of viral infections.

  20. A competitive photoelectrochemical immunosensor based on a CdS-induced signal amplification strategy for the ultrasensitive detection of dexamethasone

    PubMed Central

    Wang, Xueping; Yan, Tao; Li, Yan; Liu, Yixin; Du, Bin; Ma, Hongmin; Wei, Qin

    2015-01-01

    A novel photoelectrochemical immunosensor based on the competitive strategy is proposed for the specific detection of dexamethasone (DXM). Graphitic carbon nitride coupled with bismuth sulfide are used as the sensing matrix for the immobilization of BSA-DXM on the electrode surface, while cadmium sulfide functionalized titanium dioxide (TiO2@CdS) is used as the photoelectric active labels of anti-DXM. Due to the perfect matching of energy levels between TiO2 and CdS, the in situ prepared composite labels show excellent photocurrent response under visible lights. The competitive binding of DXM in sample solutions and BSA-DXM on the electrode surface reduces the specific attachment of labels to the electrode, resulting in a decrease of the photocurrent intensity. Greatly enhanced sensitivity is achieved after the optimization of the detection conditions. Under the optimal detection condition, the well-designed immunosensor for DXM exhibits a low detection limit of 2 pg∙mL−1. Additionally, the proposed immunoassay system shows high specificity, good reproducibility and acceptable stability, which is also expected to become a promising platform for the detection of other small molecules. PMID:26648409

  1. An Amperometric Immunosensor Based on Multi-Walled Carbon Nanotubes-Thionine-Chitosan Nanocomposite Film for Chlorpyrifos Detection

    PubMed Central

    Sun, Xia; Cao, Yaoyao; Gong, Zhili; Wang, Xiangyou; Zhang, Yan; Gao, Jinmei

    2012-01-01

    In this work, a novel amperometric immunosensor based on multi-walled carbon nanotubes-thionine-chitosan (MWCNTs-THI-CHIT) nanocomposite film as electrode modified material was developed for the detection of chlorpyrifos residues. The nanocomposite film was dropped onto a glassy carbon electrode (GCE), and then the anti-chlorpyrifos monoclonal antibody was covalently immobilized onto the surface of MWCNTs-THI-CHIT/GCE using the crosslinking agent glutaraldehyde (GA). The modification procedure was characterized by using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under the optimized conditions, a linear relationship between the relative change in peak current of different pulse voltammetry (DPV) and the logarithm of chlorpyrifos solution concentration was obtained in the range from 0.1 to 1.0 × 105 ng/mL with a detection limit of 0.046 ng/mL. The proposed chlorpyrifos immunosensor exhibited high reproducibility, stability, and good selectivity and regeneration, making it a potential alternative tool for ultrasensitive detection of chlorpyrifos residues in vegetables and fruits. PMID:23443396

  2. An ultrasensitive luminol cathodic electrochemiluminescence immunosensor based on glucose oxidase and nanocomposites: graphene-carbon nanotubes and gold-platinum alloy.

    PubMed

    Jiang, Xinya; Chai, Yaqin; Yuan, Ruo; Cao, Yaling; Chen, Yingfeng; Wang, Haijun; Gan, Xianxue

    2013-06-14

    In the present study, a novel and ultrasensitive electrochemiluminescence (ECL) immunosensor based on luminol cathodic ECL was fabricated by using Au nanoparticles and Pt nanoparticles (nano-AuPt) electrodeposited on graphene-carbon nanotubes nanocomposite as platform for the detection of carcinoembryonic antigen (CEA). For this introduced immunosensor, graphene (GR) and single wall carbon nanotubes (CNTs) dispersed in chitosan (Chi-GR-CNTs) were firstly decorated on the bare gold electrode (GE) surface. Then nano-AuPt were electrodeposited (DpAu-Pt) on the Chi-GR-CNTs modified electrode. Subsequently, glucose oxidase (GOD) was employed to block the non-specific sites of electrode surface. When glucose was present in the working buffer solution, GOD immediately catalyzed the oxidation of glucose to in situ generate hydrogen peroxide (H2O2), which could subsequently promote the oxidation of luminol with an amplified cathodic ECL signal. The proposed immunosensor was performed at low potential (-0.1 to 0.4V) and low concentration of luminol. The CEA was determined in the range of 0.1 pg mL(-1) to 40 ng mL(-1) with a limit of detection down to 0.03 pg mL(-1) (SN(-1)=3). Moreover, with excellent sensitivity, selectivity, stability and simplicity, the as-proposed luminol-based ECL immunosensor provided great potential in clinical applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Ultrasensitive electrochemiluminescence immunosensor for 5-hydroxymethylcytosine detection based on Fe3O4@SiO2 nanoparticles and PAMAM dendrimers.

    PubMed

    Jiang, Wenjing; Wu, Linni; Duan, Junling; Yin, Huanshun; Ai, Shiyun

    2018-01-15

    An ultrasensitive sandwiched electrochemiluminescence (ECL) immunosensor was developed for 5-hydroxymethylcytosine (5hmC) detection in genomic DNA by using Fe3O4@SiO2 core-shell magnetic nanomaterial as a immobilization matrix for anti-5hmC antibody, PAMAM conjugated avidin and Ru(bpy)2(phen-5-NH2)(PF6)2 as signal amplification unit. Importantly, Fe3O4@SiO2 nanoparticles were verified to not only possess enormous surface for loading antibody by amido link, but also exhibit excellent bioactivity. With the dual signal amplification strategy, the ECL immunosensor showed wide detection range from 0.1 to 30nM with low detection limit of 0.047nM (S/N = 3). Based on the specific immunoreaction, the developed method also illustrated excellent detection selectivity. The fabricated immunosensor was also applied to detect the 5hmC in genomic DNA of cancer tissue, which indicated that the immunosensor possess potential applications in clinical detection. Copyright © 2017. Published by Elsevier B.V.

  4. Sandwich-type electrochemical immunosensor for the detection of AFP based on Pd octahedral and APTES-M-CeO₂-GS as signal labels.

    PubMed

    Wei, Yicheng; Li, Yan; Li, Na; Zhang, Yong; Yan, Tao; Ma, Hongmin; Wei, Qin

    2016-05-15

    In the present work, an ultrasensitive sandwich-type electrochemical immunosensor based on a novel signal amplification strategy was designed for quantitative detection of alpha fetoprotein (AFP). Au nanoparticles with biocompatibility were electrodeposited on the surface of glassy carbon electrode (GCE) which can effectively capture and immobilize primary anti-AFP (Ab1) to significantly amplify the electrochemical signal. Graphene Oxide and CeO2 mesoporous nanocomposite functionalized by the 3-aminopropyltriethoxysilane supported Pd octahedral nanoparticles (Pd/APTES-M-CeO2-GS) were utilized as labels of detection anti-AFP (Ab2). Pd octahedral nanoparticles presented good catalytic activity towards the reduction of H2O2. Due to the large specific surface area and good adsorption properties of APTES-CeO2-GS nanocomposite, large amount of Pd octahedral nanoparticles could be immobilized, which could amplify the electrochemical signal and improve the sensitivity of the immunosensor. Under optimal conditions, the immunosensor exhibited wide linear range from 0.1 pg/mL to 50 ng/mL with a low detection limit of 0.033 pg/mL (S/N=3) for AFP detection. In addition, high sensitivity, excellent selectivity, good reproducibility and stability were obtained for the immunosensor, which has a promising application for quantitative detection of other tumor markers in clinical diagnosis.

  5. Integrated bio-affinity nano-platform into a microfluidic immunosensor based on monoclonal bispecific trifunctional antibodies for the electrochemical determination of epithelial cancer biomarker.

    PubMed

    Bravo, Karina; Ortega, Francisco G; Messina, Germán A; Sanz, María I; Fernández-Baldo, Martín A; Raba, Julio

    2017-01-01

    The epithelial cell adhesion molecule (EpCAM) is a biomarker that is highly overexpressed on the surface of epithelial carcinoma cells. In this study, silver nanoparticles covered with polyvinyl alcohol (AgNPs-PVA) were synthesized, characterized and used in a microfluidic immunosensor based on the use of anti-EpCAM recombinant antibodies as a trapping agent. The concentration of trapped EpCAM is then electrochemically quantified by HRP-conjugated anti-EpCAM-antibody. HRP reacted with its enzymatic substrate in a redox process which resulted in the appearance of a current whose magnitude (at a working voltage as low as -0.10V) is directly proportional to the concentration of EpCAM. Under optimized conditions, the detection limits for the microfluidic immunosensor and a commercial ELISA were 0.8 and 13.9pg/L, respectively. The within-assay and between-assay coefficients of variation are below 6.5% for the proposed method. The immunosensor was validated by analyzing patient samples, and a good correlation with a commercial ELISA was obtained. The good analytical performance is attributed to the efficient immobilization of the anti-EpCAM recombinant antibodies on the AgNPs-PVA, and its high specificity for EpCAM. This microfluidic immunosensor is intended for use in diagnosis and prognosis of epithelial cancer, to monitor the disease, and to assess therapeutic efficacy. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Label-free Electrochemiluminescent Immunosensor for Detection of Prostate Specific Antigen based on Aminated Graphene Quantum Dots and Carboxyl Graphene Quantum Dots.

    PubMed

    Wu, Dan; Liu, Yixin; Wang, Yaoguang; Hu, Lihua; Ma, Hongmin; Wang, Guoqin; Wei, Qin

    2016-02-04

    Prostate-specific antigen (PSA) was used as the model, an ultrasensitive label-free electrochemiluminescent immunosensor was developed based on graphene quantum dots. Au/Ag-rGO was sythsized and used as electrode material to load a great deal of graphene quantum dots due to the large surface area and excellent electron conductivity. After aminated graphene quantum dots and acarboxyl graphene quantum dots were modified onto the electrode, the ECL intensity was much high using K2S2O8 as coreactant. Then, antibody of PSA was immobilized on the surface of modified electrode surface through the adsorption of Au/Ag toward proteins, leading to the decrease of the ECL intensity. As proven by ECL spectra test and electrochemical impedance spectroscopy (EIS) analysis, the fabrication process of the immunosensor is successful. Under the optimal conditions, the ECL intensity decreased linearly with the logarithm of PSA concentration in the range of 1 pg/mL ~ 10 ng/mL. The detection limit achieved is 0.29 pg/mL. The immunosensor results were validated through the detection of PSA in serum samples with satisfactory results. Due to excellent stability, high sensitivity, acceptable repeatability and selectivity, the immunosensor has promising applications in disease and drug analysis.

  7. Luminescence-Functionalized Metal-Organic Frameworks Based on a Ruthenium(II) Complex: A Signal Amplification Strategy for Electrogenerated Chemiluminescence Immunosensors.

    PubMed

    Xiong, Cheng-Yi; Wang, Hai-Jun; Liang, Wen-Bin; Yuan, Ya-Li; Yuan, Ruo; Chai, Ya-Qin

    2015-06-26

    Novel luminescence-functionalized metal-organic frameworks (MOFs) with superior electrogenerated chemiluminescence (ECL) properties were synthesized based on zinc ions as the central ions and tris(4,4'-dicarboxylicacid-2,2'-bipyridyl)ruthenium(II) dichloride ([Ru(dcbpy)3](2+)) as the ligands. For potential applications, the synthesized MOFs were used to fabricate a "signal-on" ECL immunosensor for the detection of N-terminal pro-B-type natriuretic peptide (NT-proBNP). As expected, enhanced ECL signals were obtained through a simple fabrication strategy because luminescence-functionalized MOFs not only effectively increased the loading of [Ru(dcbpy)3](2+), but also served as a loading platform in the ECL immunosensor. Furthermore, the proposed ECL immunosensor had a wide linear range from 5 pg mL(-1) to 25 ng mL(-1) and a relatively low detection limit of 1.67 pg mL(-1) (signal/noise=3). The results indicated that luminescence-functionalized MOFs provided a novel amplification strategy in the construction of ECL immunosensors and might have great prospects for application in bioanalysis.

  8. Optimization of phosphatase- and redox cycling-based immunosensors and its application to ultrasensitive detection of troponin I.

    PubMed

    Akanda, Md Rajibul; Aziz, Md Abdul; Jo, Kyungmin; Tamilavan, Vellaiappillai; Hyun, Myung Ho; Kim, Sinyoung; Yang, Haesik

    2011-05-15

    The authors herein report optimized conditions for ultrasensitive phosphatase-based immunosensors (using redox cycling by a reducing agent) that can be simply prepared and readily applied to microfabricated electrodes. The optimized conditions were applied to the ultrasensitive detection of cardiac troponin I in human serum. The preparation of an immunosensing layer was based on passive adsorption of avidin (in carbonate buffer (pH 9.6)) onto indium-tin oxide (ITO) electrodes. The immunosensing layer allows very low levels of nonspecific binding of proteins. The optimum conditions for the enzymatic reaction were investigated in terms of the type of buffer solution, temperature, and concentration of MgCl(2), and the optimum conditions for antigen-antibody binding were determined in terms of incubation time, temperature, and concentration of phosphatase-conjugated IgG. Very importantly, the antigen-antibody binding at 4 °C is extremely important in obtaining reproducible results. Among the four phosphatase substrates (L-ascorbic acid 2-phosphate (AAP), 4-aminophenyl phosphate, 1-naphthyl phosphate, 4-amino-1-naphthyl phosphate) and four phosphatase products (L-ascorbic acid (AA), 4-aminophenol, 1-naphthol, 4-amino-1-naphthol), AAP and AA meet the requirements most for obtaining easy dissolution and high signal-to-background ratios. More importantly, fast AA electrooxidation at the ITO electrodes does not require modification with any electrocatalyst or electron mediator. Furthermore, tris(2-carboxyethyl)phosphine (TCEP) as a reducing agent allows fast redox cycling, along with very low anodic currents at the ITO electrodes. Under these optimized conditions, the detection limit of an immunosensor for troponin I obtained without redox cycling of AA by TCEP is ca. 100 fg/mL, and with redox cycling it is ca. 10 fg/mL. A detection limit of 10 fg/mL was also obtained even when an immunosensing layer was simply formed on a micropatterned ITO electrode. From a practical

  9. Enhanced sensitivity of self-assembled-monolayer-based SPR immunosensor for detection of benzaldehyde using a single-step multi-sandwich immunoassay.

    PubMed

    Gobi, K Vengatajalabathy; Matsumoto, Kiyoshi; Toko, Kiyoshi; Ikezaki, Hidekazu; Miura, Norio

    2007-04-01

    This paper describes the fabrication and sensing characteristics of a self-assembled monolayer (SAM)-based surface plasmon resonance (SPR) immunosensor for detection of benzaldehyde (BZ). The functional sensing surface was fabricated by the immobilization of a benzaldehyde-ovalbumin conjugate (BZ-OVA) on Au-thiolate SAMs containing carboxyl end groups. Covalent binding of BZ-OVA on SAM was found to be dependent on the composition of the base SAM, and it is improved very much with the use of a mixed monolayer strategy. Based on SPR angle measurements, the functional sensor surface is established as a compact monolayer of BZ-OVA bound on the mixed SAM. The BZ-OVA-bound sensor surface undergoes immunoaffinity binding with anti-benzaldehyde antibody (BZ-Ab) selectively. An indirect inhibition immunoassay principle has been applied, in which analyte benzaldehyde solution was incubated with an optimal concentration of BZ-Ab for 5 min and injected over the sensor chip. Analyte benzaldehyde undergoes immunoreaction with BZ-Ab and makes it inactive for binding to BZ-OVA on the sensor chip. As a result, the SPR angle response decreases with an increase in the concentration of benzaldehyde. The fabricated immunosensor demonstrates a low detection limit (LDL) of 50 ppt (pg mL(-1)) with a response time of 5 min. Antibodies bound to the sensor chip during an immunoassay could be detached by a brief exposure to acidic pepsin. With this surface regeneration, reusability of the same sensor chip for as many as 30 determination cycles has been established. Sensitivity has been enhanced further with the application of an additional single-step multi-sandwich immunoassay step, in which the BZ-Ab bound to the sensor chip was treated with a mixture of biotin-labeled secondary antibody, streptavidin and biotin-bovine serum albumin (Bio-BSA) conjugate. With this approach, the SPR sensor signal increased by ca. 12 times and the low detection limit improved to 5 ppt with a total response

  10. Quantum dots based potential-resolution dual-targets electrochemiluminescent immunosensor for subtype of tumor marker and its serological evaluation.

    PubMed

    Liu, Xuan; Jiang, Hui; Fang, Yuan; Zhao, Wei; Wang, Nianyue; Zang, Guizhen

    2015-09-15

    The identification of subtypes of known tumor markers is of great importance for clinical diagnosis but still a great challenge in novel detection methodologies with simple operation and acceptable sensitivity. This work for the first time reported a quantum dots (QDs) based potential-resolved electrochemiluminescent (ECL) immunosensor to realize simultaneous detection of dual targets. Because of different surface microstructures, dimercaptosuccinic acid stabilized CdTe (DMSA-CdTe) QDs and TiO2 nanoparticles-glutathione stabilized CdTe (TiO2-GSH-CdTe) QDs composites showed a large difference of ECL peak potential (∼360 mV), which provided an access for potential-resolution detection. The ECL emission on indium tin oxide electrodes showed consistent strength during the cyclic scan, and intensity data were collected at -0.89 V and -1.25 V (vs Ag/AgCl) for DMSA-CdTe QDs and TiO2-GSH-CdTe QDs composites, respectively. The interface modification procedures of immunosensor construction were characterized by atomic force microscopy. The portion of Lens culinaris lectin affiliated isoform of alpha fetoprotein (AFP), AFP-L3%, in total AFP, is recently a novel criteria showing even higher sensitivity and specificity than AFP at the early stage of cancer. Combined with the enzyme cyclic amplification strategy, linear ranges for AFP-L3 and AFP dual-targets detection were 3.24 pg mL(-1)-32.4 ng mL(-1) and 1.0 pg mL(-1)-20 ng mL(-1), with limits of detection of 3.24 pg mL(-1) and 1.0 pg mL(-1), respectively. Compared with clinical detection data, the calculated portion of AFP-L3% by as-prepared immunosensor showed acceptable accuracy. These results open a new avenue for facile and rapid multiple-components detection based on the nano-ECL technique and provide a new clinical diagnosis platform for HCC.

  11. Development of electrochemical based sandwich enzyme linked immunosensor for Cryptosporidium parvum detection in drinking water.

    PubMed

    Thiruppathiraja, Chinnasamy; Saroja, Veerappan; Kamatchiammal, Senthilkumar; Adaikkappan, Periyakaruppan; Alagar, Muthukaruppan

    2011-10-01

    Cryptosporidium parvum is one of the most important biological contaminants in drinking water and generates significant risks to public health. Due to low infectious dose of C. parvum, remarkably sensitive detection methods are required for water and food industry analysis. This present study describes a simple, sensitive, enzyme amplified sandwich form of an electrochemical immunosensor using dual labeled gold nanoparticles (alkaline phosphatase and anti-oocysts monoclonal antibody) in indium tin oxide (ITO) as an electrode to detect C. parvum. The biosensor was fabricated by immobilizing the anti-oocysts McAb on a gold nanoparticle functionalized ITO electrode, followed by the corresponding capture of analytes and dual labeled gold nanoparticle probe to detect the C. parvum target. The outcome shows the sensitivity of electrochemical immune sensor enhanced by gold nanoparticles with a limit of detection of 3 oocysts/mL in a minimal processing period. Our results demonstrated the sensitivity of the new approach compared to the customary method and the immunosensors showed acceptable precision, reproducibility, stability, and could be readily applied to multi analyte determination for environmental monitoring.

  12. Effective antibodies immobilization and functionalized nanoparticles in a quartz-crystal microbalance-based immunosensor for the detection of parathion

    PubMed Central

    Della Ventura, Bartolomeo; Iannaccone, Marco; Funari, Riccardo; Pica Ciamarra, Massimo; Altucci, Carlo; Capparelli, Rosanna; Roperto, Sante; Velotta, Raffaele

    2017-01-01

    Background Biosensor-based detection provides a rapid and low-cost alternative to conventional analytical methods for revealing the presence of the contaminants in water as well as solid matrices. Although important to be detected, small analytes (few hundreds of Daltons) are an issue in biosensing since the signal they induce in the transducer, and specifically in a Quartz-Crystal Microbalance, is undetectable. A pesticide like parathion (M = 292 Da) is a typical example of contaminant for which a signal amplification procedure is desirable. Methods/Findings The ballasting of the analyte by gold nanoparticles has been already applied to heavy target as proteins or bacteria to improve the limit of detection. In this paper, we extend the application of such a method to small analytes by showing that once the working surface of a Quartz-Crystal Microbalance (QCM) has been properly functionalized, a limit of detection lower than 1 ppb is reached for parathion. The effective surface functionalization is achieved by immobilizing antibodies upright oriented on the QCM gold surface by a simple photochemical technique (Photonic Immobilization Technique, PIT) based on the UV irradiation of the antibodies, whereas a simple protocol provided by the manufacturer is applied to functionalize the gold nanoparticles. Thus, in a non-competitive approach, the small analyte is made detectable by weighing it down through a “sandwich protocol” with a second antibody tethered to heavy gold nanoparticles. The immunosensor has been proved to be effective against the parathion while showing no cross reaction when a mixture of compounds very similar to parathion is analyzed. Conclusion/Significance The immunosensor described in this paper can be easily applied to any small molecule for which polyclonal antibodies are available since both the functionalization procedure of the QCM probe surface and gold nanoparticle can be applied to any IgG, thereby making our device of general

  13. Effective antibodies immobilization and functionalized nanoparticles in a quartz-crystal microbalance-based immunosensor for the detection of parathion.

    PubMed

    Della Ventura, Bartolomeo; Iannaccone, Marco; Funari, Riccardo; Pica Ciamarra, Massimo; Altucci, Carlo; Capparelli, Rosanna; Roperto, Sante; Velotta, Raffaele

    2017-01-01

    Biosensor-based detection provides a rapid and low-cost alternative to conventional analytical methods for revealing the presence of the contaminants in water as well as solid matrices. Although important to be detected, small analytes (few hundreds of Daltons) are an issue in biosensing since the signal they induce in the transducer, and specifically in a Quartz-Crystal Microbalance, is undetectable. A pesticide like parathion (M = 292 Da) is a typical example of contaminant for which a signal amplification procedure is desirable. The ballasting of the analyte by gold nanoparticles has been already applied to heavy target as proteins or bacteria to improve the limit of detection. In this paper, we extend the application of such a method to small analytes by showing that once the working surface of a Quartz-Crystal Microbalance (QCM) has been properly functionalized, a limit of detection lower than 1 ppb is reached for parathion. The effective surface functionalization is achieved by immobilizing antibodies upright oriented on the QCM gold surface by a simple photochemical technique (Photonic Immobilization Technique, PIT) based on the UV irradiation of the antibodies, whereas a simple protocol provided by the manufacturer is applied to functionalize the gold nanoparticles. Thus, in a non-competitive approach, the small analyte is made detectable by weighing it down through a "sandwich protocol" with a second antibody tethered to heavy gold nanoparticles. The immunosensor has been proved to be effective against the parathion while showing no cross reaction when a mixture of compounds very similar to parathion is analyzed. The immunosensor described in this paper can be easily applied to any small molecule for which polyclonal antibodies are available since both the functionalization procedure of the QCM probe surface and gold nanoparticle can be applied to any IgG, thereby making our device of general application in terms of target analyte.

  14. Sensing Escherichia coli O157:H7 via frequency shift through a self-assembled monolayer based QCM immunosensor*

    PubMed Central

    Wang, Li-jiang; Wu, Chun-sheng; Hu, Zhao-ying; Zhang, Yuan-fan; Li, Rong; Wang, Ping

    2008-01-01

    By means of the specific immuno-recognition and ultra-sensitive mass detection, a quartz crystal microbalance (QCM) biosensor for Escherichia coli O157:H7 detection was developed in this work. As a suitable surfactant, 16-mercaptohexadecanoic acid (MHDA) was introduced onto the Au surface of QCM, and then self-assembled with N-hydroxysuccinimide (NHS) raster as a reactive intermediate to provide an active interface for the specific antibody immobilization. The binding of target bacteria with the immobilized antibodies decreased the sensor’s resonant frequency, and the frequency shift was correlated to the bacterial concentration. The stepwise assembly of the immunosensor was characterized by means of the electrochemical techniques. Using the immersion-dry-immersion procedure, this QCM biosensor could detect 2.0×102 colony forming units (CFU)/ml E. coli O157:H7. In order to reduce the fabrication time, a polyelectrolyte layer-by-layer self-assembly (LBL-SA) method was adopted for fast construction. Finally, the reproducibility of this biosensor was discussed. PMID:18257134

  15. Immunosensor based on nanocomposite of nanostructured zirconium oxide and gelatin-A.

    PubMed

    Bagbi, Yana; Sharma, Anshu; Bohidar, H B; Solanki, Pratima R

    2016-01-01

    We have reported the studies related to the fabrication of a nanocomposite, comprising of sol-gel derived inorganic zirconium oxide nanoparticles (ZrO2 NPs) and organic biopolymer gelatin-A (GA), deposited on indium-tin-oxide (ITO) coated glass substrate by drop casting method. The GA-ZrO2/ITO electrode was used for immobilization of monoclonal antibodies (Ab) specific to antigen Vibrio cholerae (Vc) followed by bovine serum albumin (BSA) for antigen Vc detection using electrochemical techniques. The structural and morphological behaviour of these ZrO2 NPs, GA-ZrO2/ITO electrode and BSA/Ab/GA-ZrO2/ITO immunosensor was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy techniques. The transmission electron microscopy study exhibited a spherical shape ZrO2 NPs. The average crystalline size of ZrO2 NPs was obtained as 10.3 ± 1 nm from X-ray diffraction measurement and 72 nm hydrodynamic radius measured by dynamic light scattering. GA-ZrO2 nanocomposite provides a porous structure which assists to higher loading of Ab on the matrix surface that improved the biosensing properties. The electrochemical response studies of the fabricated BSA/Ab/GA-ZrO2/ITO immunosensor exhibited good linearity in the range of 50-400 ng mL(-1), low limit of detection of 0.74 ng/mL, sensitivity as 0.03 Ω ng(-1)mL(-1)cm(-2) and reproducibility more than 10 times.

  16. Nanoparticle-Based Electrochemical Immunosensor for the Detection of Phosphorylated Acetylcholinesterase: An Exposure Biomarker of Organophosphate Pesticides and Nerve AgentsOrganophosphate Pesticides and Nerve Agents

    SciTech Connect

    Liu, Guodong; Wang, Jun; Barry, Richard C.; Petersen, Catherine E.; Timchalk, Charles; Gassman, Paul L.; Lin, Yuehe

    2008-11-01

    A nanoparticle-based electrochemical immunosensor has been developed for the detection of phosphorylated acetylcholinesterase (AChE) adducts, which is a potential exposure biomarker for organophosphate pesticides (OP) and chemical warfare nerve agent exposures. Zirconia nanoparticles (ZrO2 NPs) were used as selective sorbents to capture the phosphorylated AChE adduct, and quantum dots (ZnS@CdS, QDs) were used as tags to label monoclonal anti-AChE antibody to track the immunorecognition events. The sandwich-like immunoreactions were performed among the ZrO2 NPs, which were pre-coated on a screen printed electrode (SPE) by electrodeposition, phosphorylated AChE and QD-anti-AChE. The captured QD tags were determined on the SPE by electrochemical stripping analysis of its metallic component (cadmium) after an acid-dissolution step. Paraoxon was used as a model OP insecticide to prepare the phosphorylated AChE adduct to demonstrate the proof of principle for this sensor technology. The paraoxon-AChE adduct was characterized by Fourier Transform Infrared Spectrum, and the binding affinity of anti-AChE to the paraoxon-AChE was validated with an enzyme-linked immunosorbent assay. The parameters (e.g., amount of ZrO2 NP, QD-anti-AChE concentration,) that govern the electrochemical response of immunosensors were optimized. The voltammetric response of the immunosensor is highly linear over the range of 10 pM to 4 nM paraoxon-AChE, and the limit of detection is estimated to be 8 pM. This new nanoparticle-based electrochemical immunosensor thus provides a sensitive and quantitative tool for biomonitoring exposure to OP pesticides and nerve agents.

  17. An Amperometric Immunosensor Based on an Ionic Liquid and Single-Walled Carbon Nanotube Composite Electrode for Detection of Tetrodotoxin in Pufferfish.

    PubMed

    Zhang, Yun; Fan, Yuxia; Wu, Jian; Wang, Xichang; Liu, Yuan

    2016-09-14

    An amperometric immunosensor based on a composite electrode of single-walled carbon nanotubes and ionic liquid n-octylpyridinum afluorophosphate (SWCNT-ILE) was developed for the determination of tetrodotoxin (TTX). Compared with the glassy carbon electrode (GCE), the electrode combined advantages of carbon nanotubes and ionic liquid, which exhibited the excellent antifouling ability of p-nitrophenol (PNP) so that it remarkably improved the stability of the p-nitrophenyl phosphate-based sensor. Combining the enzyme-linked immune sorbent assay (ELISA) by alkaline phosphatase (AP) and magnetic particles immobilized with antigens, a real-time assay of tetrodotoxin was developed by amperometric immunosensors. Under the optimium condition, the developed sensor demonstrated a linear range of tetrodotoxin from 2 to 45 ng/mL with a low detection limit of 5 ng/mL. Furthermore, the amperometric immunosensor was applied to determine TTX in real samples and could be used as an effective and sensitive sensor for direct detection of tetrodotoxin within 20 min.

  18. A disposable electrochemical immunosensor for carcinoembryonic antigen based on nano-Au/multi-walled carbon nanotubes-chitosans nanocomposite film modified glassy carbon electrode.

    PubMed

    Huang, Ke-Jing; Niu, De-Jun; Xie, Wan-Zhen; Wang, Wei

    2010-02-05

    In this paper, a disposable electrochemical immunosensor for the detection of carcinoembryonic antigen (CEA) based on Au nanoparticles (AuNPs)/multi-walled carbon nanotubes (MWCNTs)-chitosans (Chits) composite film was developed. MWCNTs-Chits homogeneous composite was first dispersed in acetic acid solution and then the AuNPs was in situ synthesized at the composite. The mixture was dripped on the glassy carbon electrode (GCE) and then CEA antibody (anti-CEA) was immobilized on the resulted modified electrode to construct the immunosensor. The stepwise assembly process of the immunosensor was characterized by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). CV and differential pulse voltammetry (DPV) studies demonstrated that the formation of antibody-antigen complexes decreased peak current of [Fe(CN)(6)](3-/4-) redox pair at the AuNPs/MWCNTs-Chits/GCE. The optimization of the pH of supporting electrolyte, the incubation temperature and time were studied in detail. Under optimal conditions, the peak current of DPV of the immunosensor decreased linearly with increasing CEA concentration in two ranges of 0.3-2.5 and 2.5-20 ng mL(-1), with a detection limit of 0.01 ng mL(-1) (S/N=3). This electrochemical immunoassay combines the specificity of the immunological reaction with the sensitivity of the AuNPs and MWCNTs amplified electrochemical detection. It would be valuable for diagnosis and monitoring of carcinoma. Copyright 2009 Elsevier B.V. All rights reserved.

  19. Sensitive detection of microcystin-LR by using a label-free electrochemical immunosensor based on Au nanoparticles/silicon template/methylene blue nanocomposite.

    PubMed

    Fu, Xuewen; Feng, Yajuan; Niu, Sipeng; Zhao, Chunling; Yang, Minghui; Yang, Yunhui

    2013-12-01

    A label-free electrochemical immunosensor, based on a gold nanoparticles (Au NPs)/silicon template/methylene blue (MB)/chitosan (CHIT) nanocomposite-modified electrode, was fabricated for the ultrasensitive detection of microcystin-LR (MC-LR). The nanocomposite film showed high binding affinity to the antibodies of MC-LR because gold nanoparticles have large surface area and good biocompatibility which can immobilize large amount of antibody through ionic interactions and other interactions between AuNPs and mercapto or primary amine groups of antibodies with high stability and bioactivity. MB was used as redox indicator due to its good electrochemical behavior in conductive substrate. This hybrid membrane was evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) to determine its electrochemical properties in immunosensor application. A decrease in DPV responses was observed with increasing concentrations of MC-LR in standard and real samples due to the formation of immuno-complexes between MC-LR and anti-MC-LR antibodies which hindered the electron charge transfer at the electrode-electrolyte interface. At optimal conditions, this immunosensor could detect MC-LR in a linear range from 0.5 ng/mL to 25 microg/mL with a low detection limit of 0.1 ng/mL at 3 sigma. Moreover, the prepared immunosensor was applied for the analysis of MC-LR in water samples with satisfactory results. The proposed method showed high selectivity, acceptable reproducibility, stability and reliability.

  20. Visible-light driven Photoelectrochemical Immunosensor Based on SnS2@mpg-C3N4 for Detection of Prostate Specific Antigen.

    PubMed

    Zhang, Yifeng; Liu, Yixin; Li, Rongxia; Saddam Khan, Malik; Gao, Picheng; Zhang, Yong; Wei, Qin

    2017-07-05

    Herein, a novel label-free photoelectrochemical (PEC) immunosensor based on SnS2@mpg-C3N4 nanocomposite is fabricated for the detection of prostate specific antigen (PSA) in human serum. Firstly, mesoporous graphite-like carbon nitride (mpg-C3N4) with carboxyl groups is synthesized successfully which possesses high specific surface area and large pore volume. Then, SnS2 as a typical n-type semiconductor with weak photoelectric conversion capability is successfully loaded on carboxylated mpg-C3N4 to form a well-matched overlapping band-structure. The as-synthesized SnS2@mpg-C3N4 nanocomposite performs outstanding photocurrent response under visible-light irradiation due to low recombination rate of photoexcited electron-hole pairs, which is transcend than pure SnS2 or pure mpg-C3N4. It is worth noting that SnS2@mpg-C3N4 nanocomposite is firstly employed as the photoactive material in PEC immunosensor area. The concentration of PSA can be analyzed by the decrease in photocurrent resulted from increased steric hindrance of the immunocomplex. Under the optimal conditions, the developed PEC immunosensor displays a liner photocurrent response in the range of 50 fg·mL(-1) ~ 10 ng·mL(-1) with a low detection limit of 21 fg·mL(-1). Furthermore, the fabricated immunosensor with satisfactory stability, reproducibility and selectivity provides a novel method for PSA determination in real sample analysis.

  1. Rapid detection of Escherichia coli O157:H7 and Salmonella Typhimurium in foods using an electrochemical immunosensor based on screen-printed interdigitated microelectrode and immunomagnetic separation.

    PubMed

    Xu, Meng; Wang, Ronghui; Li, Yanbin

    2016-01-01

    Foodborne pathogens have continuously been a serious food safety issue and there is a growing demand for a rapid and sensitive method to screen the pathogens for on-line or in-field applications. Therefore, an impedimetric immunosensor based on the use of magnetic beads (MBs) for separation and a screen-printed interdigitated microelectrode (SP-IDME) for measurement was studied for the rapid detection of Escherichia coli O157:H7 and Salmonella Typhimurium in foods. Streptavidin coated MBs were functionalized with corresponding biotinylated antibodies (Ab) to capture the target bacteria. The glucose oxidase (GOx)-Ab conjugates were employed to label the MBs-Ab-cell complexes. The yielded MBs-Ab-cell-Ab-GOx biomass was mixed with the glucose solution to trigger an enzymatic reaction which produced gluconic acid. This increased the ion strength of the solution, thus decreasing the impedance of the solution measured on the SP-IDME. Our results showed that the immunosensor was capable of specifically detecting E. coli O157:H7 and S. Typhimurium within the range of 10(2)-10(6) cfu ml(-1) in the pure culture samples. E. coli O157:H7 in ground beef and S. Typhimurium in chicken rinse water were also examined. The limits of detection (LODs) for the two bacteria in foods were 2.05×10(3) cfu g(-1) and 1.04×10(3) cfu ml(-1), respectively. This immunosensor required only a bare electrode to measure the impedance changes, and no surficial modification on the electrode was needed. It was low-cost, reproducible, easy-to-operate, and easy-to-preserve. All these merits demonstrated this immunosensor has great potential for the rapid and on-site detection of pathogenic bacteria in foods. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Immunosensors in Clinical Laboratory Diagnostics.

    PubMed

    Justino, Celine I L; Duarte, Armando C; Rocha-Santos, Teresa A P

    2016-01-01

    The application of simple, cost-effective, rapid, and accurate diagnostic technologies for detection and identification of cardiac and cancer biomarkers has been a central point in the clinical area. Biosensors have been recognized as efficient alternatives for the diagnostics of various diseases due to their specificity and potential for application on real samples. The role of nanotechnology in the construction of immunological biosensors, that is, immunosensors, has contributed to the improvement of sensitivity, since they are based in the affinity between antibody and antigen. Other analytes than biomarkers such as hormones, pathogenic bacteria, and virus have also been detected by immunosensors for clinical point-of-care applications. In this chapter, we first introduced the various types of immunosensors and discussed their applications in clinical diagnostics over the recent 6 years, mainly as point-of-care technologies for the determination of cardiac and cancer biomarkers, hormones, pathogenic bacteria, and virus. The future perspectives of these devices in the field of clinical diagnostics are also evaluated.

  3. A label-free and portable multichannel surface plasmon resonance immunosensor for on site analysis of antibiotics in milk samples.

    PubMed

    Fernández, Fátima; Hegnerová, Kateřina; Piliarik, Marek; Sanchez-Baeza, Francisco; Homola, Jiří; Marco, M-Pilar

    2010-12-15

    Techniques for immunosensing like surface plasmon resonance (SPR) may respond to the need for rapid screening methods to improve food safety. This paper describes the development of a novel portable six channel SPR biosensor based on the plasmon of gold diffraction grating surface for simultaneous multianalyte antibiotic detection in milk samples. Representative congeners from three important antibiotic families (FQs: fluoroquinolones, SAs: sulfonamides and CAP: phenicols) were chosen for this study. The chips are covalently biofunctionalized with haptenized proteins by means of a previously formed mixed self assembled monolayer (m-SAM) prepared using two types of mercapto alkyl reagents containing polyethyleneglycol (PEG) units. The samples or standards are mixed with specific polyclonal antibodies and injected into the sensor device. The detectability accomplished is very good (i.e. in buffer, enrofloxacin, 0.30 μg L(-1); sulfapyridine, 0.29 μg L(-1); and chloramphenicol, 0.26 μg L(-1)) and whole milk samples can be analyzed directly without clean-up steps, by just diluting the sample five times with water to remove non-specific interferences caused by the matrix. Although the detectability of CAP regarding the MRPL (minimum required performance limit) is slightly compromised by the dilution, the detectability accomplished by FQs and SAs was far below the maximum residue levels (MRLs) established by the European Union. Copyright © 2010 Elsevier B.V. All rights reserved.

  4. Disposable integrated bismuth citrate-modified screen-printed immunosensor for ultrasensitive quantum dot-based electrochemical assay of C-reactive protein in human serum.

    PubMed

    Kokkinos, Christos; Prodromidis, Mamas; Economou, Anastasios; Petrou, Panagiota; Kakabakos, Sotirios

    2015-07-30

    A novel immunosensor based on graphite screen-printed electrodes (SPEs) modified with bismuth citrate was developed for the voltammetric determination of C-reactive protein (CRP) in human serum using quantum dots (QDs) labels. The sandwich-type immunoassay involved physisorption of CRP capture antibody on the surface of the sensor, sequential immunoreactions with CRP and biotinylated CRP reporter antibody and finally reaction with streptavidin-conjugated PbS QDs. The quantification of the target protein was performed with acidic dissolution of the PbS QDs and anodic stripping voltammetric detection of the Pb(II) released. Detection was performed at bismuth nanodomains formed on the sensor surface during the electrolytic preconcentration step, as bismuth citrate was reduced to metallic bismuth simultaneously with the deposition of Pb on the surface of the immunosensor. Under optimal conditions, the response was linear over the range 0.2-100 ng mL(-1) CRP and the limit of detection was 0.05 ng mL(-1) CRP. Since the modified SPE serves as both the biorecognition element and the QDs reader, the analytical procedure is simplified, the drawbacks of existing electroplated immunosensors are minimized while the proposed disposable sensing platform provides convenient, low-cost and ultrasensitive detection of proteins and wider scope for mass-production.

  5. Label-free electrochemical immunosensor based on enhanced signal amplification between Au@Pd and CoFe2O4/graphene nanohybrid

    PubMed Central

    Zhang, Yong; Li, Jiaojiao; Wang, Zhiling; Ma, Hongmin; Wu, Dan; Cheng, Qianhe; Wei, Qin

    2016-01-01

    The improvement of sensitivity of electrochemical immunosensor can be achieved via two approaches: increasing loading capacities of antibody and enlarging responding electrochemical signals. Based on these, CoFe2O4/graphene nanohybrid (CoFe2O4/rGO) as support was firstly used for preparing electrochemical biosensor, and with the addition of Au@Pd nanorods (NRs) as mimic enzyme, a label-free electrochemical immunosensor was prepared. Due to the high electrical conductivity, open porous structure and large loading capacities of CoFe2O4/rGO, the enhanced signal amplification between Au@Pd NRs and CoFe2O4/rGO was studied. Fabricated as a novel substrate, the prepared immunosensor had a good analytical performance and exhibited a wide linear range from 0.01 to 18.0 ng·mL−1 with a low detection limit of 3.3 pg·mL−1 for estradiol, which was succeeded in applying to detect estradiol in the natural water. PMID:26987503

  6. A label-free electrochemiluminescence immunosensor based on EuPO4 nanowire for the ultrasensitive detection of Prostate specific antigen.

    PubMed

    Ma, Hongmin; Zhou, Jing; Li, Yan; Han, Tongqian; Zhang, Yong; Hu, Lihua; Du, Bin; Wei, Qin

    2016-06-15

    EuPO4 nanowire, which exhibited strong and stable cathodic electrochemiluminescence (ECL) activity, was used for the first time to fabricate an immunosensor for the detection of prostate specific antigen (PSA). EuPO4 has some inherent excellent properties such as long luminescence lifetime, narrow emission band, high quantum yield and low toxicity. Based on these properties, a novel label-free ECL immunosensor was developed using EuPO4 as a sensing matrix. Chitosan solution was used to disperse EuPO4 nanowires and the amino groups on chitosan enabled the covalent attachment of capture antibodies. After the modification of the electrode surface with EuPO4 nanowires, anti-PSA was then immobilized on them, forming a label-free immunosensing interface. The specific binding of PSA on the electrode inhibited the ECL reaction of EuPO4 nanowires with the coreactant due to the steric hindrance effect (Deng et al., 2013). Under the optimum conditions, a good linear relationship between ECL intensity and the logarithm of PSA concentration was obtained in the range of 0.0005-80 ng/mL with a detection limit of 177.33 fg/mL. The proposed ECL immunosensor showed good stability, acceptable selectivity and reproducibility.

  7. Ultrasensitive electrochemical immunosensor for SCCA detection based on ternary Pt/PdCu nanocube anchored on three-dimensional graphene framework for signal amplification.

    PubMed

    Liu, Yuanyuan; Ma, Hongmin; Gao, Jian; Wu, Dan; Ren, Xiang; Yan, Tao; Pang, Xuehui; Wei, Qin

    2016-05-15

    In this study, a novel and ultrasensitive sandwich-type electrochemical immunosensor was designed for the quantitative detection of squamous cell carcinoma antigen (SCCA) based on the β-cyclodextrin functionalized graphene nanosheet (CD-GN) and the ternary hollow Pt/PdCu nanocube anchored on three-dimensional graphene framework (Pt/PdCu-3DGF). CD-GN exhibited high specific surface area and good dispersibility and stability in water, which were beneficial to fix captured antibodies (Ab1) through the supramolecular host-guest interaction between CD and Ab1. The abundant oxygen-containing functional groups on 3DGF provided binding sites for anchoring noble metal nanoparticles. Pt/PdCu-3DGF could capture detected antibodies via the interaction of Pd-NH2 and Pt-NH2. Furthermore, the ternary metal nanoparticles exhibited high electrocatalytic activity toward the reduction of hydrogen peroxide. Under optimal conditions, the fabricated immunosensor showed a sensitive response to SCCA with two linear ranges. The linear ranges are 0.0001-1 ng/mL and 1-30 ng/mL with a detection limit of 25 fg/mL. Additionally, the proposed immunosensor showed good reproducibility and stability. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Single-step cycle pulse operation of the label-free electrochemiluminescence immunosensor based on branched polypyrrole for carcinoembryonic antigen detection

    PubMed Central

    Zhu, Wenjuan; Wang, Qi; Ma, Hongmin; Lv, Xiaohui; Wu, Dan; Sun, Xu; Du, Bin; Wei, Qin

    2016-01-01

    A novel label-free electrochemiluminescence (ECL) immunosensor based on luminol functional-Au NPs@polypyrrole has been developed for the detection of carcinoembryonic antigen (CEA). In this work, polypyrrole prepared by chemical polymerization provided a large surface area to load amounts of gold nanoparticles (Au NPs). Au NPs could not only attach abundant luminol for the enhancement of ECL signal, but also provide a friendly microenvironment for the immobilization of antibodies. Moreover, 1-butylpyridinium tetrafluroborate ([BPy]BF4) were used to disperse luminol functional-Au NPs@polypyrrole nanocomposites, resulting in the film-formation of composites on the electrode, which could improve the stability of immunosensor. In particular, employment of single-step cycle pulse could limit the consecutive reaction between luminol and H2O2 efficiently, thus leading to stable and strong signals. The proposed method presents good ECL response for the detection of CEA allowing a wide linear range from 0.01 pg/mL to 10 ng/mL and a limit of detection as low as 3 fg/mL. The immunosensor would be a promising tool in the early diagnosis of CEA due to its high sensitivity, simplicity and cost-effective. PMID:27091590

  9. Single-step cycle pulse operation of the label-free electrochemiluminescence immunosensor based on branched polypyrrole for carcinoembryonic antigen detection.

    PubMed

    Zhu, Wenjuan; Wang, Qi; Ma, Hongmin; Lv, Xiaohui; Wu, Dan; Sun, Xu; Du, Bin; Wei, Qin

    2016-04-19

    A novel label-free electrochemiluminescence (ECL) immunosensor based on luminol functional-Au NPs@polypyrrole has been developed for the detection of carcinoembryonic antigen (CEA). In this work, polypyrrole prepared by chemical polymerization provided a large surface area to load amounts of gold nanoparticles (Au NPs). Au NPs could not only attach abundant luminol for the enhancement of ECL signal, but also provide a friendly microenvironment for the immobilization of antibodies. Moreover, 1-butylpyridinium tetrafluroborate ([BPy]BF4) were used to disperse luminol functional-Au NPs@polypyrrole nanocomposites, resulting in the film-formation of composites on the electrode, which could improve the stability of immunosensor. In particular, employment of single-step cycle pulse could limit the consecutive reaction between luminol and H2O2 efficiently, thus leading to stable and strong signals. The proposed method presents good ECL response for the detection of CEA allowing a wide linear range from 0.01 pg/mL to 10 ng/mL and a limit of detection as low as 3 fg/mL. The immunosensor would be a promising tool in the early diagnosis of CEA due to its high sensitivity, simplicity and cost-effective.

  10. A highly sensitive enzyme-amplified immunosensor based on a nanoporous niobium oxide (Nb2O5) electrode.

    PubMed

    Lee, Chang-Soo; Kwon, Dohyoung; Yoo, Jeng Eun; Lee, Byung Gun; Choi, Jinsub; Chung, Bong Hyun

    2010-01-01

    We report on the development of an enzyme-amplified sandwich-type immunosensor based on a thin gold film sputtered on an anodic nanoporous niobium oxide (Au@Nb(2)O(5)) electrode. The electrocatalytic activity of enzymatically amplified electroactive species and a stable electrode consisting of Au@Nb(2)O(5) were used to obtain a powerful signal amplification of the electrochemical immunobiosensor. The method using this electrochemical biosensor based on an Au@Nb(2)O(5) electrode provides a much better performance than those based on conventional bulk gold or niobium oxide electrodes. Our novel approach does not require any time-consuming cleaning steps to yield reproducible electrochemical signals. In addition, the strong adhesion of gold films on the niobium oxide electrodes offers a very stable substrate during electrochemical biosensing. Cyclic voltammetry measurements indicate that non-specific binding of proteins to the modified Au@Nb(2)O(5) surface is sufficiently low to be ignored in the case of our novel system. Finally, we demonstrated the ability of the biosensor based on an Au@Nb(2)O(5) offering the enhanced performance with a high resolution and sensitivity. Therefore, it is expected that the biosensor based on an Au@Nb(2)O(5) has great potential for highly efficient biological devices.

  11. Diagnosis of schistosomiasis japonica with interfacial co-assembly-based multi-channel electrochemical immunosensor arrays

    NASA Astrophysics Data System (ADS)

    Deng, Wangping; Xu, Bin; Hu, Haiyan; Li, Jianyong; Hu, Wei; Song, Shiping; Feng, Zheng; Fan, Chunhai

    2013-05-01

    Schistosomiasis control remains to be an important and challenging task in the world. However, lack of quick, simple, sensitive and specific sero-diagnostic test is still a hurdle in the control practice. The commonly employed enzyme-linked immuno-sorbent assay (ELISA) relies on the native soluble egg antigen (SEA) that is limited in supply. Here we developed an electrochemical immunosensor array (ECISA) assay with an interfacial co-assembly strategy. A recombinant Schistosoma japonicum (Sj) calcium-binding protein (SjE16) was used as a principal antigen, while the SEA as a minor, co-assembling agent, with a ratio of 8:1 (SjE16: SEA, Sj16EA), which was co-immobilized on a disposable 16-channel screen-printed carbon electrode array. A portable electrochemical detector was employed to detect antibodies in serum samples. The sensitivity of ECISA reached 100% with minimal cross-reactions. Therefore, we have demonstrated that this rapid, sensitive and specific ECISA technique has the potential to perform large-scale on-site screening of Sj infection.

  12. Label-Free Detection of Gliadin in Food by Quartz Crystal Microbalance-Based Immunosensor.

    PubMed

    Funari, Riccardo; Terracciano, Irma; Della Ventura, Bartolomeo; Ricci, Sara; Cardi, Teodoro; D'Agostino, Nunzio; Velotta, Raffaele

    2017-02-15

    Gluten is a protein composite found in wheat and related grains including barley, rye, oat, and all their species and hybrids. Gluten matrix is a biomolecular network of gliadins and glutenins that contribute to the texture of pastries, breads, and pasta. Gliadins are mainly responsible for celiac disease, one of the most widespread food-related pathologies in Western world. In view of the importance of gliadin proteins, by combining the quartz crystal microbalance technology, a cheap and robust piezoelectric transducer, with the so-called photonic immobilization technique, an effective surface functionalization method that provides spatially oriented antibodies on gold substrates, we realized a sensitive and reliable biosensor for quantifying these analytes extracted from real samples in a very short time. The resulting immunosensor has a limit of detection of about 4 ppm and, more remarkably, shows excellent sensitivity in the range 7.5-15 ppm. This feature makes our device reliable and effective for practical applications since it is able to keep low the influence of false positives.

  13. Single-Multiplex Detection of Organ Injury Biomarkers using SPRi based Nano-Immunosensor

    PubMed Central

    Zeidan, Effat; Li, Siqi; Zhou, Zhiguo; Miller, Jennifer; Sandros, Marinella G.

    2016-01-01

    The clinical assessment of multiple organ dysfunctions at early stages is recognized to be an important factor in prompting definitive treatment decisions that prevent irreversible organ damage. In this article, we propose a real-time, label-free, and multiplex nanoenhanced SPRi platform to quantitatively assess two biomarkers, kidney injury molecule (KIM-1) and high mobility group box-1 (HMGB-1) simultaneously in buffer. Our work involves three major contributions in the design of the immunosensor: (1) we applied site-specific immobilization of antibodies to the solid surface that avoids loss of biological activity caused by covalent attachment; (2) we constructed a well-blocked sensor surface that exhibits minimal non-specific adsorption for singleplex measurements of each biomarker in buffer; and (3) we adopted a sandwich assay that implements functionalized quantum dots (NanoEnhancers) as signal amplifiers to achieve a sensitivity level of 5 pg/mL for KIM-1 and HMGB-1 in buffer. We foresee great potential and success in extending this multiplex and ultra-sensitive platform to assess a variety of other emerging clinical biomarkers at low concentrations and in complex matrices. PMID:27796342

  14. Diagnosis of schistosomiasis japonica with interfacial co-assembly-based multi-channel electrochemical immunosensor arrays.

    PubMed

    Deng, Wangping; Xu, Bin; Hu, Haiyan; Li, Jianyong; Hu, Wei; Song, Shiping; Feng, Zheng; Fan, Chunhai

    2013-01-01

    Schistosomiasis control remains to be an important and challenging task in the world. However, lack of quick, simple, sensitive and specific sero-diagnostic test is still a hurdle in the control practice. The commonly employed enzyme-linked immuno-sorbent assay (ELISA) relies on the native soluble egg antigen (SEA) that is limited in supply. Here we developed an electrochemical immunosensor array (ECISA) assay with an interfacial co-assembly strategy. A recombinant Schistosoma japonicum (Sj) calcium-binding protein (SjE16) was used as a principal antigen, while the SEA as a minor, co-assembling agent, with a ratio of 8:1 (SjE16: SEA, Sj16EA), which was co-immobilized on a disposable 16-channel screen-printed carbon electrode array. A portable electrochemical detector was employed to detect antibodies in serum samples. The sensitivity of ECISA reached 100% with minimal cross-reactions. Therefore, we have demonstrated that this rapid, sensitive and specific ECISA technique has the potential to perform large-scale on-site screening of Sj infection.

  15. Development of an enrofloxacin immunosensor based on label-free electrochemical impedance spectroscopy.

    PubMed

    Wu, Ching-Chou; Lin, Chia-Hung; Wang, Way-Shyan

    2009-06-30

    Enrofloxacin is the most widespread antibiotic in the fluoroquinolone family. As such, the development of a rapid and sensitive method for the determination of trace amounts of enrofloxacin is an important issue in the health field. The interaction of the enrofloxacin antigen to a specific antibody (Ab) immobilized on an 11-mercapto-undecanoic acid-coated gold electrode was quantified by electrochemical impedance spectroscopy. Two equivalent circuits were separately used to interpret the obtained impedance spectra. These circuits included one resistor in series with one parallel circuit comprised of a resistor and a capacitor (1R//C), and one resistor in series with two parallel RC circuits (2R//C). The results indicate that the antigen-antibody reaction analyzed using the 1R//C circuit provided a more sensitive resistance increment against the enrofloxacin concentration than that of the 2R//C circuit. However, the 2R//C circuit provided a better fitting for impedance spectra, and therefore supplies more detailed results of the enrofloxacin-antibody interaction, causing the increase of electron transfer resistance selectively to the modified layer, and not the electrical double layer. The antibody-modified electrode allowed for analysis of the dynamic linear range of 1-1000 ng/ml enrofloxacin with a detection limit of 1 ng/ml. The reagentless and label-free impedimetric immunosensors provide a simple and sensitive detection method for the specific determination of enrofloxacin.

  16. Amperometric Immunosensor for Carbofuran Detection Based on MWCNTs/GS-PEI-Au and AuNPs-Antibody Conjugate

    PubMed Central

    Zhu, Ying; Cao, Yaoyao; Sun, Xia; Wang, Xiangyou

    2013-01-01

    In this paper, an amperometric immunosensor for the detection of carbofuran was developed. Firstly, multiwall carbon nanotubes (MWCNTs) and graphene sheets-ethyleneimine polymer-Au (GS-PEI-Au) nanocomposites were modified onto the surface of a glass carbon electrode (GCE) via self-assembly. The nanocomposites can increase the surface area of the GCE to capture a large amount of antibody, as well as produce a synergistic effect in the electrochemical performance. Then the modified electrode was coated with gold nanoparticles-antibody conjugate (AuNPs-Ab) and blocked with BSA. The monoclonal antibody against carbofuran was covalently immobilized on the AuNPs with glutathione as a spacer arm. The morphologies of the GS-PEI-Au nanocomposites and the fabrication process of the immunosensor were characterized by X-ray diffraction (XRD), ultraviolet and visible absorption spectroscopy (UV-vis) and scanning electron microscopy (SEM), respectively. Under optimal conditions, the immunosensor showed a wide linear range, from 0.5 to 500 ng/mL, with a detection limit of 0.03 ng/mL (S/N = 3). The as-constructed immunosensor exhibited notable performance features such as high specificity, good reproducibility, acceptable stability and regeneration performance. The results are mainly due to the excellent properties of MWCNTs, GS-PEI-Au nanocomposites and the covalent immobilization of Ab with free hapten binding sites for further immunoreaction. It provides a new avenue for amperometric immunosensor fabrication. PMID:23604029

  17. REVIEW ARTICLE: Trends in interfacial design for surface plasmon resonance based immunoassays

    NASA Astrophysics Data System (ADS)

    Shankaran, Dhesingh Ravi; Miura, Norio

    2007-12-01

    Immunosensors based on surface plasmon resonance (SPR) have become a promising tool in sensor technology for biomedical, food, environmental, industrial and homeland security applications. SPR is a surface sensitive optical technique, suitable for real-time and label-free analysis of biorecognition events at functional transducer surfaces. Fabrication of highly active and robust sensing surfaces is an important part in immunoassays because the quality, quantity, chemistry and topography of the interfacial biomembranes play a major role in immunosensor performance. Eventually, a variety of immobilization methods such as physical adsorption, covalent coupling, Langmuir Blodgett film, polymer thin film, self-assembly, sol gel, etc, have been introduced over the years for the immobilization of biomolecules (antibody or antigen) on the transducer surfaces. The selection of an immobilization method for an immunoassay is governed by several factors such as nature and stability of the biomolecules, target analyte, application, detection principle, mode of signal transduction, matrix complexity, etc. This paper provides an overview of the various surface modification methods for SPR based immunosensor fabrication. The preparation, structure and application of different functional interfacial surfaces have been discussed along with a brief introduction to the SPR technology, biomolecules and detection principles.

  18. Optical waveguide lightmode spectroscopy technique-based immunosensor development for aflatoxin B1 determination in spice paprika samples.

    PubMed

    Majer-Baranyi, Krisztina; Zalán, Zsolt; Mörtl, Mária; Juracsek, Judit; Szendrő, István; Székács, András; Adányi, Nóra

    2016-11-15

    Optical waveguide lightmode spectroscopy (OWLS) technique has been applied to label-free detection of aflatoxin B1 in a competitive immunoassay format, with the aim to compare the analytical goodness of the developed OWLS immunosenor with HPLC and enzyme-linked immunosorbent assay (ELISA) methods for the detection of aflatoxin in spice paprika matrix. We have also assessed applicability of the QuEChERS method prior to ELISA measurements, and the results were compared to those obtained by traditional solvent extraction followed by immunoaffinity clean-up. The AFB1 content of sixty commercial spice paprika samples from different countries were measured with the developed and optimized OWLS immunosensor. Comparing the results from the indirect immunosensor to that obtained by HPLC or ELISA provided excellent correlation (with regression coefficients above 0.94) indicating that the competitive OWLS immunosensor has a potential for quick determination of aflatoxin B1 in paprika samples.

  19. Silica nanoparticle-based microfluidic immunosensor with laser-induced fluorescence detection for the quantification of immunoreactive trypsin.

    PubMed

    Seia, Marco A; Stege, Patricia W; Pereira, Sirley V; De Vito, Irma E; Raba, Julio; Messina, Germán A

    2014-10-15

    The purpose of this study was to develop a silica nanoparticle-based immunosensor with laser-induced fluorescence (LIF) as a detection system. The proposed device was applied to quantify the immunoreactive trypsin (IRT) in cystic fibrosis (CF) newborn screening. A new ultrasonic procedure was used to extract the IRT from blood spot samples collected on filter papers. After extraction, the IRT reacted immunologically with anti-IRT monoclonal antibodies immobilized on a microfluidic glass chip modified with 3-aminopropyl functionalized silica nanoparticles (APSN-APTES-modified glass chips). The bounded IRT was quantified by horseradish peroxidase (HRP)-conjugated anti-IRT antibody (anti-IRT-Ab) using 10-acetyl-3,7-dihydroxyphenoxazine (ADHP) as enzymatic mediator. The HRP catalyzed the oxidation of nonfluorescent ADHP to highly fluorescent resorufin, which was measured by LIF detector, using excitation lambda at 561nm and emission at 585nm. The detection limits (LODs) calculated for LIF detection and for a commercial enzyme-linked immunosorbent assay (ELISA) test kit were 0.87 and 4.2ngml(-1), respectively. The within- and between-assay variation coefficients for the LIF detection procedure were below 6.5%. The blood spot samples collected on filter papers were analyzed with the proposed method, and the results were compared with those of the reference ELISA method, demonstrating a potential usefulness for the clinical assessment of IRT during the early neonatal period.

  20. Enzyme-free electrochemical immunosensor based on methylene blue and the electro-oxidation of hydrazine on Pt nanoparticles.

    PubMed

    Dutta, Gorachand; Nagarajan, Sureshbabu; Lapidus, Lisa J; Lillehoj, Peter B

    2017-06-15

    Enzyme-free electrochemical sensors enable rapid, high sensitivity measurements without the limitations associated with enzyme reporters. However, the performance of non-enzymatic electrochemical sensors tends to suffer from slow electrode kinetics and poor signal stability. We report a new enzyme-free electrochemical immunosensor based on a unique competitive detection scheme using methylene blue (MB), hydrazine and platinum nanoparticles (Pt NPs). This scheme is coupled with a robust immunosandwich format employing a MB-labelled detection antibody as a non-enzymatic reporter. In the presence of the target antigen, surface-immobilized MB consumes interfacial hydrazine thereby diminishing the electro-oxidation of hydrazine on Pt NPs. Thus, the concentration of the antigen is directly proportional to the reduction in the electrochemical signal. For proof-of-concept, this sensor was used to detect Plasmodium falciparum histidine-rich protein 2 (PfHRP2), an important malaria biomarker, in unadulterated human saliva samples. Chronocoulometric measurements showed that this platform exhibits pM-range sensitivity, high specificity and good reproducibility, making it well suited for many biosensing applications including noninvasive diagnostic testing.

  1. Fiber Optic Surface Plasmon Resonance-Based Biosensor Technique: Fabrication, Advancement, and Application.

    PubMed

    Liang, Gaoling; Luo, Zewei; Liu, Kunping; Wang, Yimin; Dai, Jianxiong; Duan, Yixiang

    2016-05-03

    Fiber optic-based biosensors with surface plasmon resonance (SPR) technology are advanced label-free optical biosensing methods. They have brought tremendous progress in the sensing of various chemical and biological species. This review summarizes four sensing configurations (prism, grating, waveguide, and fiber optic) with two ways, attenuated total reflection (ATR) and diffraction, to excite the surface plasmons. Meanwhile, the designs of different probes (U-bent, tapered, and other probes) are also described. Finally, four major types of biosensors, immunosensor, DNA biosensor, enzyme biosensor, and living cell biosensor, are discussed in detail for their sensing principles and applications. Future prospects of fiber optic-based SPR sensor technology are discussed.

  2. Ultrasensitive sandwich-type electrochemical immunosensor based on a novel signal amplification strategy using highly loaded palladium nanoparticles/carbon decorated magnetic microspheres as signal labels.

    PubMed

    Ji, Lei; Guo, Zhankui; Yan, Tao; Ma, Hongmin; Du, Bin; Li, Yueyun; Wei, Qin

    2015-06-15

    An ultrasensitive sandwich-type electrochemical immunosensor for quantitative detection of alpha fetoprotein (AFP) was proposed based on a novel signal amplification strategy in this work. Carbon decorated Fe3O4 magnetic microspheres (Fe3O4@C) with large specific surface area and good adsorption property were used as labels to anchor palladium nanoparticles (Pd NPs) and the secondary antibodies (Ab2). Pd NPs were loaded on Fe3O4@C to obtain Fe3O4@C@Pd with core-shell structure by electrostatic attraction, which were further used to immobilize Ab2 due to the bonding of Pd-NH2. A signal amplification strategy was the noble metal nanoparticles, such as Pd NPs, exhibiting high electrocatalytic activities toward hydrogen peroxide (H2O2) reduction. This signal amplification was novel not only because of the great capacity, but also the ease of magnetic separation from the sample solution based on their magnetic property. Moreover, carboxyl-functionalized multi-walled carbon nanotubes (MWCNTs-COOH) were used for the immobilization of primary antibodies (Ab1). Therefore, high sensitivity could be realized by the designed immunosensor based on this novel signal amplification strategy. Under optimal conditions, the immunosensor exhibited a wide linear range of 0.5 pg/mL to 10 ng/mL toward AFP with a detection limit of 0.16 pg/mL (S/N=3). Moreover, it revealed good selectivity, acceptable reproducibility and stability, indicating a potential application in clinical monitoring of tumor biomarkers. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Ultrasensitive electrochemical immunosensor based on dual signal amplification process for p16(INK4a) cervical cancer detection in clinical samples.

    PubMed

    Duangkaew, Pattasuda; Tapaneeyakorn, Satita; Apiwat, Chayachon; Dharakul, Tararaj; Laiwejpithaya, Somsak; Kanatharana, Proespichaya; Laocharoensuk, Rawiwan

    2015-12-15

    The p16(INK4a) (p16) is a cyclin-dependent kinase inhibitor, which has been evaluated in several studies as a diagnostic marker of cervical cancer. Immunostaining using p16 specific antibody has confirmed an over-expression of p16 protein in cervical cancer cells and its association with disease progression. This article reports an ultrasensitive electrochemical immunosensor for specific detection of p16 and demonstrates its performance for detection of solubilized p16 protein in cell lysates obtained from patients. Sandwich-based immunoreaction couple with double signal amplification strategy based on catalytic enlargement of particle tag was used for high sensitivity and specificity. The conditions were optimized to create an immunoassay protocol. Disposable screen-printed electrode modified with capture antibodies (Ab1) was selected for further implementation towards point-of-care diagnostics. Small gold nanoparticles (15 nm diameter) conjugated with detection antibodies (Ab2) were found to better serve as a detection label due to limited interference with antigen-antibody interaction. Double signal enhancement was performed by sequential depositions of gold and silver layers. This gave the sensitivity of 1.78 μA mL(ng GST-p16)(-1) cm(-2) and detection limit of 1.3 ng mL(-1) for GST-p16 protein which is equivalent to 0.49 ng mL(-1) for p16 protein and 28 cells for HeLa cervical cancer cells. In addition to purified protein, the proposed immunosensor effectively detected elevated p16 level in cervical swab samples obtained from 10 patients with positive result from standard Pap smear test, indicating that an electrochemical immunosensors hold an excellent promise for detection of cervical cancer in clinical setting. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Electrochemical immunosensor based on bismuth nanocomposite film and cadmium ions functionalized titanium phosphates for the detection of anthrax protective antigen toxin.

    PubMed

    Sharma, Mukesh K; Narayanan, J; Upadhyay, Sanjay; Goel, Ajay K

    2015-12-15

    Bacillus anthracis is a bioterrorism agent classified by the Centers for Disease Control and Prevention (CDC). Herein, a novel electrochemical immunosensor for the sensitive, specific and easy detection of anthrax protective antigen (PA) toxin in picogram concentration was developed. The immunosensor consists of (i) a Nafion-multiwall carbon nanotubes-bismuth nanocomposite film modified glassy carbon electrodes (BiNPs/Nafion-MWCNTs/GCE) as a sensing platform and (ii) titanium phosphate nanoparticles-cadmium ion-mouse anti-PA antibodies (TiP-Cd(2+)-MαPA antibodies) as signal amplification tags. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), thermogravimmetric analysis (TGA), Fourier transform-infra red spectroscopy (FT-IR), zeta-potential analysis, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were employed to characterize the synthesized TiP nanoparticles and modified electrode surfaces. The immunosensing performance of BiNPs/Nafion-MWCNTs/GCE was evaluated based on sandwich immunoassay protocol. A square wave voltammetry (SWV) scan from -1.2 to -0.3 V in HAc-NaAc buffer solution (pH 4.6) without stripping process was performed to record the electrochemical responses at -0.75 V corresponding to high content of Cd(2+) ions loaded in TiP nanoparticles for the measurement of PA toxin. Under optimal conditions, the currents increased with increasing PA toxin concentrations in spiked human serum samples and showed a linear range from 0.1 ng/ml to 100 ng/ml. The limit of detection of developed immunosensor was found to be 50 pg/ml at S/N=3. The total time of analysis was 35 min.

  5. A highly sensitive prostate-specific antigen immunosensor based on gold nanoparticles/PAMAM dendrimer loaded on MWCNTS/chitosan/ionic liquid nanocomposite.

    PubMed

    Kavosi, Begard; Salimi, Abdollah; Hallaj, Rahman; Amani, Kamal

    2014-02-15

    We have developed a sensitive electrochemical immunosensor for the detection of prostate-specific antigen (PSA), based on covalently immobilizing of anti-PSA and redox mediator (thionine) onto gold nanoparticles-incorporated polyamidoamine dendrimer (AuNPs-PAMAM) and multiwalled carbon nanotubes/ionic liquid/chitosan nanocomposite (MWCNTs/IL/Chit) as the support platform. The MWCNTs/IL/Chit nanocomposite and synthesized AuNPs were characterized using SEM and TEM microscopy techniques. Greatly amplified immunoassay was established by sandwiching the antigen between anti-PSA immobilized on the MWCNTs/IL/Chit/AuNPs-PAMAM interface and anti-PSA labeled with horseradish peroxidase (HRP-labeled anti-PSA) as secondary antibody. Phtaloyl chloride (Ph) was used as linking agent for the subsequent immobilization of AuNPs-PAMAM onto platform and anti-PSA antibody and thionine onto AuNPs-PAMAM dendrimer. The increased electrocatalytic reduction of H2O2 by HRP was monitored by differential pulse voltammetry technique. Under optimized condition the calibration curve for PSA concentration was linear up to 80 ng ml(-1) with detection limit (signal-to-noise ratio of 3) of 1 pg ml(-1). AuNPs-PAMAM dendrimer as platform not only increased the amount of thionine and PSA antibody but also the electron transfer process accelerated by encapsulated AuNPs. Moreover, the proposed PSA immunosensor exhibited excellent stability and reproducibility. Accurate detection of PSA in human serum samples was demonstrated by comparison to standard ELISA assays. In addition, impedance technique was used as simple, rapid, low cost label free analytical method for PSA measurement with detection limit of 0.5 ng ml(-1) at concentration range up to 25 ng ml(-1). The results indicate that the present protocol is quite promising in developing other electrochemical immunosensors. © 2013 Elsevier B.V. All rights reserved.

  6. Colloidal graphene as a transducer in homogeneous fluorescence-based immunosensor for rapid and sensitive analysis of microcystin-LR.

    PubMed

    Liu, Meng; Zhao, Huimin; Chen, Shuo; Yu, Hongtao; Quan, Xie

    2012-11-20

    Herein, we reported the assembly of colloidal graphene (CG) and microcystin (MC)-LR-DNA bioconjugates to develop a homogeneous competitive fluorescence-based immunoassay for rapid and sensitive detection of MC-LR in water samples. Initially, the MC-LR-DNA probe was quickly adsorbed onto the CG surface through the strong noncovalent π-π stacking interactions and can be effectively quenched benefiting from the high quenching efficiency of CG. In contrast, the competitive binding of anti-MC-LR with MC-LR-DNA destroyed the graphene/MC-LR-DNA interaction, thus resulting in the restoration of fluorescence signal. This signal transduction mechanism made it possible for analysis of the target MC-LR. Taking advantage of the colloidal nature of the as-prepared graphene, the assay was carried out in homogeneous solution throughout, which avoided numerous immobilization, incubation, and washing steps that were necessary to traditional heterogeneous immunoassays, thereby reducing the whole assay time (within less than 35 min) and allowing a much better antigen-antibody interaction. Moreover, due to the direct competitive mode, the assay did not involve any antibody labeling or modification process, which would be beneficial to preserve the binding affinity of antigen-antibody. Under optimal conditions, the proposed immunosensor can be applied for quantitative analysis of MC-LR with a detection limit of 0.14 μg/L, which satisfied the World Health Organization (WHO) provisional guideline limit of 1 μg/L for MC-LR in drinking water, thus providing a powerful tool for rapid and sensitive monitoring of MC-LR in environmental samples.

  7. Magnetically-actuated, bead-enhanced silicon photonic immunosensor

    PubMed Central

    Valera, Enrique; McClellan, Melinda S.; Bailey, Ryan C.

    2015-01-01

    Magnetic actuation has been introduced to an optical immunosensor technology resulting in improvements in both rapidity and limit of detection for an assay quantitating low concentrations of a representative protein biomarker. For purposes of demonstration, an assay was designed for monocyte chemotactic protein 1 (MCP-1), a small cytokine which regulates migration and infiltration of monocytes and macrophages, and is an emerging biomarker for several diseases. The immunosensor is based on arrays of highly multiplexed silicon photonic microring resonators. A one-step sandwich immunoassay was performed and the signal was further enhanced through a tertiary recognition event between biotinylated tracer antibodies and streptavidin-coated magnetic beads. By integrating a magnet under the sensor chip, magnetic beads were rapidly directed towards the sensor surface resulting in improved assay performance metrics. Notably, the time required in the bead binding step was reduced by a factor of 11 (4 vs 45 min), leading to an overall decrease in assay time from 73 min to 32 min. The magnetically-actuated assay also lowered the limit of detection (LOD) for MCP-1 from 124 pg mL−1 down to 57 pg mL−1. In sum, the addition of magnetic actuation into bead-enhanced sandwich assays on a silicon photonic biosensor platform might facilitate improved detection of biomarkers in point-of-care diagnostics settings. PMID:26528374

  8. Immunosensor based on electrodeposition of gold-nanoparticles and ionic liquid composite for detection of Salmonella pullorum.

    PubMed

    Wang, Dan; Dou, Wenchao; Zhao, Guangying; Chen, Yan

    2014-11-01

    In order to increase the reproducibility and stability of electrochemical immunosensor, which is a key issue for its application and popularization, an accurate and stable immunosensor for rapid detection of Salmonella pullorum (S. pullorum) was proposed in this study. The immunosensor was fabricated by modifying Screen-printed Carbon Electrode (SPCE) with electrodeposited gold nanoparticles (AuNPs), HRP-labeled anti-S. pullorum and ionic liquids (ILs) (AuNP/HRP/IL). AuNPs are electrodeposited on the working electrode surface to increase the amount of antibodies that bind to the electrode and then modified with ILs to protect the antibodies from being inactivated in the test environment and maintain their biological activity and the stability of the detection electrode. The electrochemical characteristics of the stepwise modified electrodes and the detection of S. pullorum were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). As shown in the results of the experiments, AuNPs with unique electrochemical properties as well as biocompatibility characteristics have been proven to be able to strengthen the antibody combination effectively and to increase the electrochemical response signal. In addition, a crucial assessment regarding implementation of stability and reproducibility analysis of a range of immunosensors is provided. We found that application of AuNPs/ILs in the immune modified electrodes showed obvious improvement when compared with other groups. Given their high levels of reproducibility, stability, target specificity and sensitivity, AuNPs and ILs were considered to be excellent elements for electrode modification. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Recent advances in immunosensor for narcotic drug detection

    PubMed Central

    Gandhi, Sonu; Suman, Pankaj; Kumar, Ashok; Sharma, Prince; Capalash, Neena; Suri, C. Raman

    2015-01-01

    Introduction: Immunosensor for illicit drugs have gained immense interest and have found several applications for drug abuse monitoring. This technology has offered a low cost detection of narcotics; thereby, providing a confirmatory platform to compliment the existing analytical methods. Methods: In this minireview, we define the basic concept of transducer for immunosensor development that utilizes antibodies and low molecular mass hapten (opiate) molecules. Results: This article emphasizes on recent advances in immunoanalytical techniques for monitoring of opiate drugs. Our results demonstrate that high quality antibodies can be used for immunosensor development against target analyte with greater sensitivity, specificity and precision than other available analytical methods. Conclusion: In this review we highlight the fundamentals of different transducer technologies and its applications for immunosensor development currently being developed in our laboratory using rapid screening via immunochromatographic kit, label free optical detection via enzyme, fluorescence, gold nanoparticles and carbon nanotubes based immunosensing for sensitive and specific monitoring of opiates. PMID:26929925

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

    PubMed Central

    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

  11. An ultrasensitive label-free electrochemical immunosensor based on signal amplification strategy of multifunctional magnetic graphene loaded with cadmium ions

    PubMed Central

    Li, Faying; Li, Yueyun; Dong, Yunhui; Jiang, Liping; Wang, Ping; Liu, Qing; Liu, Hui; Wei, Qin

    2016-01-01

    Herein, a novel and ultrasensitive label-free electrochemical immunosensor was proposed for quantitative detection of human Immunoglobulin G (IgG). The amino functionalized magnetic graphenes nanocomposites (NH2-GS-Fe3O4) were prepared to bond gold and silver core-shell nanoparticles (Au@Ag NPs) by constructing stable Au-N and Ag-N bond between Au@Ag NPs and -NH2. Subsequently, the Au@Ag/GS-Fe3O4 was applied to absorb cadmium ion (Cd2+) due to the large surface area, high conductivity and exceptional adsorption capability. The functional nanocomposites of gold and silver core-shell magnetic graphene loaded with cadmium ion (Au@Ag/GS-Fe3O4/Cd2+) can not only increase the electrocatalytic activity towards hydrogen peroxide (H2O2) but also improve the effective immobilization of antibodies because of synergistic effect presented in Au@Ag/GS-Fe3O4/Cd2+, which greatly extended the scope of detection. Under the optimal conditions, the proposed immunosensor was used for the detection of IgG with good linear relation in the range from 5 fg/mL to 50 ng/mL with a low detection limit of 2 fg/mL (S/N = 3). Furthermore, the proposed immunosensor showed high sensitivity, special selectivity and long-term stability, which had promising application in bioassay analysis. PMID:26880596

  12. A label-free electrochemical immunosensor for hepatitis B based on hyaluronic acid-carbon nanotube hybrid film.

    PubMed

    Cabral, Diego G A; Lima, Erika C S; Moura, Patrícia; Dutra, Rosa F

    2016-01-01

    An electrochemical immunosensor developed for detection of antibodies to hepatitis B core protein (anti-HBc) is described. Anti-HBc is the earliest serological marker from hepatitis B virus (HBV) infection, remaining all life after contact with virus, being considered the most important marker for uses in screening of blood bank. A nanohybrid surface assembled onto a glassy carbon electrode consisting of amino carbon nanotubes recovered by hyaluronic acid was used as sensing platform to detect the anti-HBc. All the steps of electrode surface modification were characterized by Scanning Electronic Microscopy and extensively evaluated by electrochemical techniques. The electrode response was measured by direct anti-HBc antigen interactions by square wave voltammetry, dispensing uses of label or chemical mediators. Under optimal conditions, the anodic peak current which was proportional to the anti-HBs concentration. The immunosensor response was linear toward anti-HBc in concentrations up to 6 ng mL(-1), with a detection limit of 0.03 ng mL(-1). The linear range achieved was according to clinical level, indicating the immunosensor as promising tool for use as a criterion for blood bag disposal. The enhancement of the hyaluronic acid by carbon nanotube promoted an increase of charge electron transfer, besides a stable platform for HBc. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. An ultrasensitive label-free electrochemical immunosensor based on signal amplification strategy of multifunctional magnetic graphene loaded with cadmium ions

    NASA Astrophysics Data System (ADS)

    Li, Faying; Li, Yueyun; Dong, Yunhui; Jiang, Liping; Wang, Ping; Liu, Qing; Liu, Hui; Wei, Qin

    2016-02-01

    Herein, a novel and ultrasensitive label-free electrochemical immunosensor was proposed for quantitative detection of human Immunoglobulin G (IgG). The amino functionalized magnetic graphenes nanocomposites (NH2-GS-Fe3O4) were prepared to bond gold and silver core-shell nanoparticles (Au@Ag NPs) by constructing stable Au-N and Ag-N bond between Au@Ag NPs and -NH2. Subsequently, the Au@Ag/GS-Fe3O4 was applied to absorb cadmium ion (Cd2+) due to the large surface area, high conductivity and exceptional adsorption capability. The functional nanocomposites of gold and silver core-shell magnetic graphene loaded with cadmium ion (Au@Ag/GS-Fe3O4/Cd2+) can not only increase the electrocatalytic activity towards hydrogen peroxide (H2O2) but also improve the effective immobilization of antibodies because of synergistic effect presented in Au@Ag/GS-Fe3O4/Cd2+, which greatly extended the scope of detection. Under the optimal conditions, the proposed immunosensor was used for the detection of IgG with good linear relation in the range from 5 fg/mL to 50 ng/mL with a low detection limit of 2 fg/mL (S/N = 3). Furthermore, the proposed immunosensor showed high sensitivity, special selectivity and long-term stability, which had promising application in bioassay analysis.

  14. Ultrasensitive sandwich-type electrochemical immunosensor based on trimetallic nanocomposite signal amplification strategy for the ultrasensitive detection of CEA

    PubMed Central

    Tian, Lihui; Liu, Li; Li, Yueyuan; Wei, Qin; Cao, Wei

    2016-01-01

    A novel and ultrasensitive sandwich-type electrochemical immunosensor was designed for the quantitative detection of carcino-embryonic antigen (CEA). This immunosensor was developed by using the trimetallic NiAuPt nanoparticles on graphene nanosheets (NGs) nanosheets (NiAuPt-NGs) as excellent labels and β-cyclodextrin functionalized reduced graphene oxide nanosheets (CD-NGs) as the platform. The CD-NGs with high specific surface area good biocompatibility and the ideal dispersibility was used to capture the primary antibodies (Ab1) efficiently. The trimetallic NiAuPt-NGs nanocomposites were used as the labels for signal amplification, showing better electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2), which is much better than that the monometallic Pt-NGs, bimetallic NiPt-NGs and AuPt-NGs due to the synergetic effect presented in NiAuPt-NGs. The NiAuPt-NGs nanocomposites consist of tightly coupled nanostructures of Au, Ni and Pt, which have neither an alloy nor a core-shell structure. Under the optimal conditions, a linear range from 0.001–100 ng/mL and a low detection limit of 0.27 pg/mL were obtained for CEA. The proposed electrochemical sandwich-type immunosensor may have a promising application in bioassay and it enriches the electrochemical immunoassays. PMID:27488806

  15. Nitrogen-doped graphene-chitosan matrix based efficient chemiluminescent immunosensor for detection of chicken interleukin-4.

    PubMed

    Yang, Zhanjun; Lu, Mimi; Li, Juan; Tan, Zining; Dai, Hua; Jiao, Xin'an; Hu, Xiaoya

    2017-03-15

    Chicken interleukin-4 (ChIL-4), which is released by activated type 2 helper (Th2) cells following their stimulation in vitro, is an important indicator for the study of cell-mediated immunity in chickens after infection or vaccination. In this work, the first ChIL-4 chemiluminescent (CL) immunosensor was developed via the immobilization of monoclonal ChIL-4 antibodies on a nitrogen-doped graphene (NG)-chitosan nanocomposite matrix. NG nanosheets were used for the first time in the CL immunoassay to provide a biocompatible microenvironment for the immobilized capture antibody. The ChIL-4 immunosensor was characterized systematically. The proposed immunosensor displayed a wide linear range from 0.05 to 70ngmL(-1) and a low detection limit of 0.02ngmL(-1) at a signal-to-noise ratio of 3. Compared to traditional assay methods, this system was more flexible, simple, rapid, and sensitive. Moreover, this CL immunoassay system had an excellent detection and fabrication reproducibility, a high specificity, an acceptable accuracy, and a high stability. This work enables the specific detection of ChIL-4 and the further study of its role in the immune responses of poultry. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. A novel label-free electrochemical immunosensor based on functionalized nitrogen-doped graphene quantum dots for carcinoembryonic antigen detection.

    PubMed

    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.

  17. Label-free electrochemical immunosensor based on gold-silicon carbide nanocomposites for sensitive detection of human chorionic gonadotrophin.

    PubMed

    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. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Electrochemical immunosensor based on hydrophilic polydopamine-coated prussian blue-mesoporous carbon for the rapid screening of 3-bromobiphenyl.

    PubMed

    Sun, Zihong; Luo, Zhigang; Gan, Cuifen; Fei, Shidong; Liu, Yingju; Lei, Hongtao

    2014-09-15

    A sensitive electrochemical immunosensor for 3-bromobiphenyl (3-BBP) detection was constructed by employing a new polydopamine coated prussian blue-mesoporous carbon (PDOP/PB/CMK-3) nanocomposite as the substrate platform and multi-horseradish peroxidase-double helix carbon nanotubes-secondary antibody (multi-HRP-DHCNTs-Ab2) as the signal label. PB/CMK-3 was firstly successfully in-situ synthesized with the aid of the CMK-3 reduction, which was characterized by transmission electron microscope (TEM), infrared spectroscopy (IR), X-ray diffraction (XRD) and N2 adsorption-desorption analysis. By using PDOP/PB/CMK-3 as the substrate, it can effectively enhance the specific surface for antigen loading due to the three-dimensional structure of the nanocomposites, while large amount of PB that fixed inside or outside the pore of CMK-3 successfully improved the electrochemical response and the PDOP film can provide a biocompatible environment to maintain the activity of antigen availability. Under the optimized conditions, the proposed immunosensor shows a good current response to 3-BBP in a linear range from 5 pM to 2 nM with a detection limit of 2.25 pM. In addition, the specificity, reproducibility and stability of the immunosensor were also proved to be acceptable, indicating its potential application in environmental monitoring. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Ultrasensitive electrochemical immunosensor based on horseradish peroxidase (HRP)-loaded silica-poly(acrylic acid) brushes for protein biomarker detection.

    PubMed

    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.

  20. A novel sandwiched electrochemiluminescence immunosensor for the detection of carcinoembryonic antigen based on carbon quantum dots and signal amplification.

    PubMed

    Li, Nian-Lu; Jia, Li-Ping; Ma, Rong-Na; Jia, Wen-Li; Lu, Yi-Yang; Shi, Sha-Shan; Wang, Huai-Sheng

    2017-03-15

    In this study, a novel sandwiched electrochemiluminescence (ECL) immunosensor for the detection of carcinoembryonic antigen (CEA) was developed. The nanocomposite of polydopamine and Ag nanoparticles (PDA-AgNPs) was prepared by the redox reaction between Ag(+) and dopamine. This nanocomposite not only provided an effective matrix for the immobilization of primary antibody (Ab1) but also enhanced the conductivity of the electrode. Carbon quantum dots (CQDs) were immobilized on the poly(ethylenimine) functionalized graphene oxide (PEI-GO) through amido-bond. Then Au nanoparticles were decorated on the CQDs modified PEI-GO matrix, and the resulted complex AuNPs/CQDs-PEI-GO was introduced to link secondary antibody (Ab2). The CQDs can be connected to the electrode surface through the combination of CEA with Ab1 and Ab2, and then the amplified electrochemiluminescence signal of CQDs was obtained with the synergistic effect of AgNPs, polydopamine, AuNPs and PEI-GO. Under the optimal conditions, the ECL intensity was proportional to the logarithm value of CEA concentration in the linear range from 5pgmL(-1) to 500ngmL(-1) with a detection limit of 1.67pgmL(-1) for CEA detection. The immunosensor was applied for the CEA detection in real samples with satisfactory results. The proposed ECL immunosensor showed good performance with high sensitivity, specificity, reproducibility, stability and will be potential in clinical detection.

  1. An enhanced sensitive electrochemical immunosensor based on efficient encapsulation of enzyme in silica matrix for the detection of human immunodeficiency virus p24.

    PubMed

    Fang, Yi-Shan; Huang, Xin-Jian; Wang, Li-Shi; Wang, Ju-Fang

    2015-02-15

    We report a new electrochemical immunosensor for enhanced sensitive detection of human immunodeficiency virus p24 (HIV-p24) based on graphene oxide (GO) as a nanocarrier and enzyme encapsulated in carbon nanotubes-silica as a matrix in a multienzyme amplification strategy. Greatly enhanced sensitivity was achieved by using the bioconjugates featuring horseradish peroxidase-HIV-p24 signal antibody (HRP-HIV-p24) linked to functionalized GO and thionine (TH) as well as efficient encapsulation of enzyme (HRP) in the silica matrix with retained bioactivity. After a sandwich immunoreactions, the HRP in carbon nanotubes-silica matrix and the HRP-HIV-p24-TH/GO captured onto the electrode surface produced an amplified electrocatalytic response by the reduction of enzymatically oxidized thionine in the presence of hydrogen peroxide. The increase of response current was proportional to the HIV-p24 concentration in the range of 0.5 pg/mL-8.5 ng/mL with the detection limit of 0.15 pg/mL, which was lower than that of the traditional sandwich electrochemical measurement for HIV-p24. The amplified immunoassay developed in this work shows acceptable stability and reproducibility, and the assay results for HIV-p24 spiked in human plasma also show good accuracy. This simple and low-cost immunosensor shows great promise for detection of other proteins and clinical applications.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

    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

  4. Microfluidic immunosensor based on mesoporous silica platform and CMK-3/poly-acrylamide-co-methacrylate of dihydrolipoic acid modified gold electrode for cancer biomarker detection.

    PubMed

    Regiart, Matías; Fernández-Baldo, Martin A; Villarroel-Rocha, Jhonny; Messina, Germán A; Bertolino, Franco A; Sapag, Karim; Timperman, Aaron T; Raba, Julio

    2017-04-22

    We report a hybrid glass-poly (dimethylsiloxane) microfluidic immunosensor for epidermal growth factor receptor (EGFR) determination, based on the covalent immobilization of anti-EGFR antibody (anti-EGFR) on amino-functionalized mesoporous silica (AMS) retained in the central channel of a microfluidic device. The synthetized AMS was characterized by N2 adsorption-desorption isotherm, scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and infrared spectroscopy. The cancer biomarker was quantified in human serum samples by a direct sandwich immunoassay measuring through a horseradish peroxidase-conjugated anti-EGFR. The enzymatic product was detected at -100 mV by amperometry on a sputtering gold electrode, modified with an ordered mesoporous carbon (CMK-3) in a matrix of poly-acrylamide-co-methacrylate of dihydrolipoic acid (poly(AC-co-MDHLA)) through in situ copolymerization. CMK-3/poly(AC-co-MDHLA)/gold was characterized by cyclic voltammetry, EDS and SEM. The measured current was directly proportional to the level of EGFR in human serum samples. The linear range was from 0.01 ng mL(-1) to 50 ng mL(-1). The detection limit was 3.03 pg mL(-1), and the within- and between-assay coefficients of variation were below 5.20%. The microfluidic immunosensor is a very promising device for the diagnosis of several kinds of epithelial origin carcinomas.

  5. Electrochemical magneto immunosensor based on endogenous β-galactosidase enzyme to determine enterotoxicogenic Escherichia coli F4 (K88) in swine feces using square wave voltammetry.

    PubMed

    Viviana Tarditto, Lorena; Alicia Zon, María; García Ovando, Hugo; Roberto Vettorazzi, Nelio; Javier Arévalo, Fernando; Fernández, Héctor

    2017-11-01

    Diseases caused by enterotoxicogenic Escherichia coli F4 (K88) (ETEC F4) are a problem in swine production establishments. Due to the high rate of mortality and morbidity of E. coli infections, a rapid and accurate diagnosis is important in order to choose an appropriate treatment to reduce the economic impact. Therefore, an electrochemical magneto-immunosensor (EMI) was developed to detect and quantify ETEC F4 in swine feces samples through a direct non-competitive immunoassay. ETEC F4 was selectively captured by immunomagnetic separation. The detection principle was based on the activity of β-galactosidase endogenous enzyme (β-gal), which hydrolyses the p-aminophenyl-β-D-galactopyranoside (p-APG) producing p-aminophenol (p-AP), which was oxidized on a carbon screen printed electrode (CSPE) using square wave voltammetry (SWV). All parameters related to construction and electrochemical responses were optimized. The total analysis time to quantify ETEC F4 using the EMI was less than 2h and the limit of detection (LOD) was 33CFUmL(-1). The perceptual relative error (%Er) was 20%. The magneto-immunosensor was validated versus conventional method of culture and plate count, obtaining a very good agreement. The EMI is simple, fast and economical to detect and quantify ETEC F4 in swine feces samples, being thus a valuable tool in swine production. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. A novel multiple signal amplifying immunosensor based on the strategy of in situ-produced electroactive substance by ALP and carbon-based Ag-Au bimetallic as the catalyst and signal enhancer.

    PubMed

    Zhang, Si; Li, Renkai; Liu, Xiaoying; Yang, Liuqing; Lu, Qiujun; Liu, Meiling; Li, Haitao; Zhang, Youyu; Yao, Shouzhuo

    2017-06-15

    In this work, a novel immunosensor was constructed based on the alkaline phosphatase (ALP) in situ generating an electroactive substance by enzymatic hydrolysis the inactive substrates. The new signal-amplified strategy for sensitive detection of HIgG was based on the catalytic oxidation of ALP-generated products, ascorbic acid (AA), using carbon-based Ag-Au bimetallic as the catalyst and signal enhancer. Through a sandwich reaction, ALP-Ab2 bioconjugates were captured on the electrode surface and the amplified signal can be obtained as follows: the ALP catalyzed the inactive substrate L-ascorbic acid 2-phosphate (AAP) to in situ produce AA; AA as an electroactive product then can be directly electro-oxidized to generate electrochemical signal; At the same time, AA could be catalytic oxidized by Ag-Au bimetallic and resulted in the amplification of electrochemical signal; Finally, the oxidation of Ag on the Ag-Au bimetallic maybe further enhance the detection signal. The proposed immunosensor achieved good linear in the range of 0.005-100ngmL(-1) with the detection limit of 0.0009ngmL(-1) (S/N =3). The proposed immunosensor was successfully applied in the analysis of human IgG in real samples and got satisfied results. The present work demonstrates a general strategy for the design of multifunctional nanomaterials based on carbon-based bimetallic nanoparticles for different applications, such as biosensors, immunosensors and nanocatalysts. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Sensitive immunosensor for benzo[a]pyrene detection based on dual amplification strategy of PAMAM dendrimer and amino-modified methylene blue/SiO₂ core-shell nanoparticles.

    PubMed

    Lin, Mouhong; Liu, Yingju; Liu, Chuanhe; Yang, Zhuohong; Huang, Yibin

    2011-05-15

    A novel electrochemical immunosensor for sensitive detection of benzo[a]pyrene (BaP) is constructed using poly(amido amine) (PAMAM) dendrimer and functionalized methylene blue/SiO2 core-shell nanoparticle (MB/SiO2) loaded with horseradish peroxidase (HRP) and HRP-secondary antibody (HRP-Ab2). Greatly enhanced sensitivity for BaP analysis is based on a dual signal amplification strategy. Firstly, the gold electrode (GE) was amino-functioned by electropolymerization of a novel compound, 2-amino-5,2':5'2''-terthiophene, followed by the modification of G 2.0 PAMAM dendrimer to amplify functional groups on the substrate and thus enhance the immobilization capacity of BaP antigen (BaP-Ag). Secondly, amino-functionalized MB/SiO2 was used to load HRP and HRP-Ab2, and the resulting nanostructure (HRP-MB/SiO2-Ab2) was applied as the detection label for the immunosensor. The proposed immunosensor exhibited a relatively wide linear response between 0.01 and 2.0 ng/mL with a detection limit of 6 pg/mL. This amplification strategy shows excellent promise for environmental monitoring of some pollutants and a potential application in the immunosensor. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. A novel self-enhanced electrochemiluminescence immunosensor based on hollow Ru-SiO2@PEI nanoparticles for NSE analysis

    NASA Astrophysics Data System (ADS)

    Zhou, Limin; Huang, Jianshe; Yu, Bin; You, Tianyan

    2016-02-01

    Poly(ethylenimine) (PEI) and Ru(bpy)32+-doped silica (Ru-SiO2) nanoparticles were simply mixed together to prepare a novel self-enhanced electrochemiluminescence (ECL) composite of Ru-SiO2@PEI. The hollow Ru-SiO2@PEI nanoparticles were used to build an ECL immunosensor for the analysis of neuron specific enolase (NSE). PEI not only assembled on the surface of Ru-SiO2 nanoparticles through the electrostatic interaction to act as co-reactant for Ru(bpy)32+ ECL, but also provided alkaline condition to etch the Ru-SiO2 nanoparticles to form the hollow Ru-SiO2@PEI nanoparticles with porous shell. The unique structure of the Ru-SiO2@PEI nanoparticles loaded both a large amount of Ru(bpy)32+ and its co-reactant PEI at the same time, which shortened the electron-transfer distance, thereby greatly enhanced the luminous efficiency and amplified the ECL signal. The developed immunosensor showed a wide linear range from 1.0 × 10‑11 to 1.0 × 10‑5 mg mL‑1 with a low detection limit of 1.0 × 10‑11 mg mL‑1 for NSE. When the immunosensor was used for the determination of NSE in clinical human serum, the results were comparable with those obtained by using enzyme-linked immunosorbent assay (ELISA) method. The proposed method provides a promising alternative for NSE analysis in clinical samples.

  9. Microfluidic immunosensor with micromagnetic beads coupled to carbon-based screen-printed electrodes (SPCEs) for determination of Botrytis cinerea in tissue of fruits.

    PubMed

    Fernández-Baldo, Martín A; Messina, Germán A; Sanz, Maria I; Raba, Julio

    2010-11-10

    A wide range of plant species, including economically important crops such as vegetables, ornamentals, bulbs, and fundamentally fruits, can be affected by gray mold caused by the fungal pathogen Botrytis cinerea . This paper describes the development of a microfluidic immunosensor with micromagnetic beads (MMBs) coupled to carbon-based screen-printed electrodes (SPCEs) for the rapid and sensitive quantification of B. cinerea in apple (Red Delicious), table grape (pink Moscatel), and pear (William's) tissues. The detection of B. cinerea was carried out using a competitive immunoassay method based on the use of purified B. cinerea antigens immobilized on 3-aminopropyl-modified MMBs. The total assay time was 40 min, and the calculated detection limit was 0.008 μg mL(-1). Moreover, the intra- and interassay coefficients of variation were below 7%. The developed method allowed detects B. cinerea even in asymptomatic fruits and promises to be particularly useful for application in the agricultural industry.

  10. A review on novel developments and applications of immunosensors in food analysis.

    PubMed

    Ricci, Francesco; Volpe, Giulia; Micheli, Laura; Palleschi, Giuseppe

    2007-12-19

    The present review deals with novel developments in immunosensors destined for final application in food analysis. In this perspective particular emphasis will be given to the most important approaches which recently have been used for immunosensor construction and assembling. For this reason, electrochemical, surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) techniques will be explored in detail and recent and practical examples on food matrices will be reviewed. Objective of this survey is to give a general overview of the possible application of immunosensors to the food analysis field.

  11. A reagentless electrochemiluminescent immunosensor for apurinic/apyrimidinic endonuclease 1 detection based on the new Ru(bpy)3(2+)/bi-arginine system.

    PubMed

    Zhao, Min; Chai, Xi Deng Ya-Qin; Han, Jing; Gui, Guo-Feng; Yuan, Ruo; Zhuo, Ying

    2014-10-10

    Apurinic/apyrimidinic endonuclease 1 (APE-1), a kind of multifunctional protein widely-distributed in the body, plays an essential role in the DNA base excision repair and serves as multiple possible roles in the response of human cancer to radiotherapy and chemotherapy. In this work, an ultrasensitive solid-state electrochemiluminescence (ECL) immunosensor is designed to determine APE-1 based on the new Ru(bpy)3(2+)/bi-arginine system. The bi-arginine (bi-Arg) is decorated on the Au nanoparticles functionalized magnetic Fe3O4/reduced graphene oxide (bi-Arg/Au@Fe3O4-rGO) according to the self-assembling and covalent cross-linking interaction to obtain the functionalized nanocomposite of bi-Arg/Au@Fe3O4-rGO. Herein, the bi-Arg/Au@Fe3O4-rGO plays not only an amplification label to enhance the ECL signal of Ru(bpy)3(2+) due to the coreactant of bi-Arg but also an ideal nanocarrier to load numerous secondary antibody. Based on sandwich-type immunoassay format, this proposed method offers a linear range of 1.0fgmL(-1)-5.0pgmL(-1) and an estimated detection limit of 0.3fgmL(-1) for the APE-1. Moreover, the reagentless ECL immunosensor also exhibits high sensitivity, excellent selectivity and good stability, which has greatly potential development and application in clinical diagnostics, immunology and biomedical research.

  12. Development of a recombinant Fab-fragment based electrochemical immunosensor for deoxynivalenol detection in food samples.

    PubMed

    Romanazzo, Daniela; Ricci, Francesco; Volpe, Giulia; Elliott, Christopher T; Vesco, Silvia; Kroeger, Katy; Moscone, Danila; Stroka, Joerg; Van Egmond, Hans; Vehniäinen, Markus; Palleschi, Giuseppe

    2010-08-15

    A reliable and cost-effective electrochemical method for the detection of deoxynivalenol (DON) in cereals and cereal-based food samples based on the use of a novel anti-DON Fab fragment is presented. The analytical system employed, Enzyme-Linked-Immunomagnetic-Electrochemical (ELIME) assay, is based on the use of immunomagnetic beads (IMBs) coupled with eight magnetized screen-printed electrodes (8-mScPEs) as electrochemical transducers. Using standard solutions of DON, a working range between 100 and 4500 ng/ml was obtained with an EC(50) of 380 ng/ml. The ELIME assay was employed to evaluate the cross-reactivity of the Fab fragment towards different trichothecenes revealing a good selectivity towards DON over other trichothecenes with the exception of 3-Ac-DON. The sensor was then applied to cereals and cereal-based food samples (wheat, breakfast cereal and baby-food) and a wide range of sample treatment procedures was tested. Within-laboratory precision (9-24% repeatability for breakfast cereals and 10-33% for baby-food) and recovery data (82-110% for breakfast cereals and 97-108% for baby-food) were calculated by analyzing blank breakfast cereals and baby-foods fortified with DON, demonstrating that the proposed method has the capability for use as a screening assay for DON in such products. Copyright 2010 Elsevier B.V. All rights reserved.

  13. A new phosphothreonine lyase electrochemical immunosensor for detecting Salmonella based on horseradish peroxidase/GNPs-thionine/chitosan.

    PubMed

    Lu, Dingqiang; Pang, Guangchang; Xie, Junbo

    2017-03-01

    In the current study, a novel double-layer gold nanoparticles- electrochemical immunosensor electrode (DGN-EIE) immobilized with Salmonella plasmid virulence C (SpvC) antibody was developed. To increase the fixed quantity of antibodies and electrochemical signal, an electrochemical biosensing signal amplification system was utilized with gold nanoparticles-thionine-chitosan absorbing horseradish peroxidase (HRP). In addition, the SpvC monoclonal antibodies (derived from Balb/c mice) were prepared and screened with a high affinity to SpvC. To evaluate the quality of DGN-EIE, the amperometric I-t curve method was applied to determine Salmonella in PBS. The results showed that the response current had a good linear correlation with the bacterial quantity ranged from 1.0 × 10(1)-5.0 × 10(4) cfu/mL. The lowest detection limit was found at 5 cfu/mL. Furthermore, the proposed immunosensor has been demonstrated with high sensitivity, good selectivity and reproducibility. Apparently, DGN-EIE may be a very useful tool for monitoring the bacteria.

  14. Label-free immunosensor based on graphene/polyaniline nanocomposite for neutrophil gelatinase-associated lipocalin detection.

    PubMed

    Yukird, Jutiporn; Wongtangprasert, Tossapon; Rangkupan, Ratthapol; Chailapakul, Orawon; Pisitkun, Trairak; Rodthongkum, Nadnudda

    2017-01-15

    A novel label-free electrochemical immunosensor for neutrophil gelatinase-associated lipocalin (NGAL) detection has been developed. The immunosensor has been constructed by immobilization of NGAL capture antibodies to electropolymerized aniline deposited on top of an electrosprayed graphene/polyaniline (G/PANI) modified screen printed carbon electrode. Electrospraying of G/PANI increases the electrode surface area while electropolymerization of aniline increases the number of amino groups (-NH2) for antibody immobilization. The factors affecting the sensor sensitivity (i.e. aniline concentration, scan number and scan rate of electropolymerization) have been optimized. In a prior report, Kannan et al. reported a broad oxidation peak in cyclic voltammetry upon the binding between NGAL with its antibody. In this study, a dramatic increase (58-fold) in the oxidation current upon the binding between NGAL and its antibody is obtained when compared to an unmodified electrode, verifying a substantial improvement in the electrochemical sensitivity of this system. Under optimal conditions, this system exhibits high sensitivity with a limit of detection (LOD) of 21.1ngmL(-1), wide linearity (50-500ngmL(-1)) and high specificity toward NGAL detection from small samples (10μL). As an example application, the sensor is tested for the detection of NGAL in human urine, and the results correspond well with the values obtained from a standard ELISA. Compared to the ELISA method, our system requires less analysis time (≤30min/sample), less sample and less operating cost.

  15. Nano-magnetic immunosensor based on staphylococcus protein a and the amplification effect of HRP-conjugated phage antibody.

    PubMed

    Mu, Xihui; Tong, Zhaoyang; Huang, Qibin; Liu, Bing; Liu, Zhiwei; Hao, Lanqun; Zhang, Jinping; Gao, Chuan; Wang, Fenwei

    2015-02-09

    In this research, super-paramagnetic Fe3O4 nanoparticles (magnetic particles) were coated with Staphylococcus protein A (SPA) and coupled with polyclonal antibody (pcAb) to construct magnetic capturing probes, and HRP-conjugated phage antibody was then used as specific detecting probe to design a labeled immunosensor for trace detection of Staphylococcus aureus enterotoxin B (SEB). The linear detection range of the sensor was 0.008~125 µg/L, the regression equation was Y = 0.487X + 1.2 (R = 0.996, N = 15, p < 0.0001), the limit of detection (LOD) was 0.008 µg/L, and the limit of quantification (LOQ) was 0.008 µg/L. HRP-conjugated phage antibody, SPA and magnetic particles can enhance the sensitivity 4-fold, 3-fold and 2.6-fold higher, respectively. Compared with conventional double-antibody sandwich ELISA, the detection sensitivity of the sensor was 31-fold higher resulting from the integrated amplifying effect. The immunosensor integrates the unique advantages of SPA-oriented antibody as magnetic capturing probe, HRP-conjugated phage antibody as detecting probe, magnetic separation immunoassay technique, and several other advanced techniques, so it achieves high sensitivity, specificity and interference-resistance. It is proven to be well suited for analysis of trace SEB in various environmental samples with high recovery rate and reproducibility.

  16. An electrochemical ELISA-like immunosensor for miRNAs detection based on screen-printed gold electrodes modified with reduced graphene oxide and carbon nanotubes.

    PubMed

    Tran, H V; Piro, B; Reisberg, S; Huy Nguyen, L; Dung Nguyen, T; Duc, H T; Pham, M C

    2014-12-15

    We design an electrochemical immunosensor for miRNA detection, based on screen-printed gold electrodes modified with reduced graphene oxide and carbon nanotubes. An original immunological approach is followed, using antibodies directed to DNA.RNA hybrids. An electrochemical ELISA-like amplification strategy was set up using a secondary antibody conjugated to horseradish peroxidase (HRP). Hydroquinone is oxidized into benzoquinone by the HRP/H2O2 catalytic system. In turn, benzoquinone is electroreduced into hydroquinone at the electrode. The catalytic reduction current is related to HRP amount immobilized on the surface, which itself is related to miRNA.DNA surface density on the electrode. This architecture, compared to classical optical detection, lowers the detection limit down to 10 fM. Two miRNAs were studied: miR-141 (a prostate biomarker) and miR-29b-1 (a lung cancer biomarker). Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Sensitive Immunosensor for Cancer Biomarker Based on Dual Signal Amplification Strategy of Graphene Sheets and Multi-Enzyme Functionalized Carbon Nanospheres

    SciTech Connect

    Du, Dan; Zou, Zhexiang; Shin, Yongsoon; Wang, Jun; Wu, Hong; Engelhard, Mark H.; Liu, Jun; Aksay, Ilhan A.; Lin, Yuehe

    2010-03-30

    A novel electrochemical immunosensor for sensitive detection of cancer biomarker α fetoprotein (AFP) is described that uses a graphene sheet sensor platform and functionalized carbon nanospheres (CNSs) labeling with horseradish peroxidase-secondary antibodies (HRP-Ab2). Greatly enhanced sensitivity for the cancer biomarker is based on a dual signal amplification strategy: first, the synthesized CNSs yielded a homogeneous and narrow size distribution, which allowed several binding events of HRP-Ab2 on each nanosphere. Enhanced sensitivity was achieved by introducing the multi-bioconjugates of HRP-Ab2-CNSs onto the electrode surface through sandwich immunoreactions. Secondly, functionalized graphene sheets used for the biosensor platform increased the surface area to capture a large amount of primary antibodies (Ab1), thus amplifying the detection response. This amplification strategy is a promising platform for clinical screening of cancer biomarkers and point-of-care diagnostics.

  18. Ultra-sensitive plasmonic nanometal scattering immunosensor based on optical control in the evanescent field layer.

    PubMed

    Lee, Seungah; Park, Guenyoung; Chakkarapani, Suresh Kumar; Kang, Seong Ho

    2015-01-15

    Novel, fluorescence-free detection of biomolecules on nanobiochips was investigated based on plasmonic nanometal scattering in the evanescent field layer (EFL) using total internal reflection scattering (TIRS) microscopy. The plasmonic scattering of nanometals bonded to biomolecules was observed at different wavelengths by an electromagnetic field in the EFL. The changes in the scattering of nanometals on the gold-nanopatterned chip in response to the immunoreaction between silver nanoparticles and antibodies allowed fluorescence-free detection of biomolecules on the nanobiochips. Under optimized conditions, the TIRS immunoassay chip detected different amounts of immobilized antigen, i.e., human cardiac troponin I. The sandwich immuno-reaction was quantitatively analyzed in the dynamic range of 720 zM-167 fM. The limit of detection (S/N=4) was 600 zM, which was ~140 times lower than limits obtained by previous total internal reflection fluorescence and dark field methods. These results demonstrate the possibility for a fluorescence-free biochip nanoimmunoassay based on the scattering of nanometals in the EFL.

  19. Flow-based impedimetric immunosensor for aflatoxin analysis in milk products.

    PubMed

    Kanungo, Lizy; Bacher, Gautam; Bhand, Sunil

    2014-10-01

    Label-free detection technique based on impedance was investigated for aflatoxin M1 (AFM1) and aflatoxin M2 (AFM2) analysis in milk products. The impedance change resulting from antigen-antibody interaction was studied using a two-electrode setup made up of silver (Ag) wire. Processed milk such as drinking yogurt and flavored milk samples were analyzed in a flow-based setup. Two microflow pumps were used to construct the flow system where analytes (AFM1 and AFM2) were injected and impedance was measured using functionalized Ag wire electrodes. The flow system was optimized by adjusting both inlet and outlet flows to maintain the reaction volume optimum for impedance measurements. Using Bode plot, the matrix effect was investigated for detection of AFM1 and AFM2 in various matrices. Good recoveries were obtained even at low-AFM1 concentrations in the range of 1-100 pg/mL. The influence of AFM2 on the detection of AFM1 was also investigated. The proposed method provides good scope for online monitoring of such hazardous toxins in milk products.

  20. Quantum dot based immunosensor using 3D circular microchannels fabricated in PDMS.

    PubMed

    Morarka, Amit; Agrawal, Shailaja; Kale, Sonia; Kale, Anup; Ogale, Satish; Paknikar, Kishore; Bodas, Dhananjay

    2011-02-15

    Microchannel is basic functional component of microfluidic chip and every step-forward of its construction technique has been receiving concern all over the world. The present work describes a novel, rapid and simple fabrication technique for building 3D microchannels in poly(dimethyl siloxane) (PDMS) elastomer. These microchannels were used for rapid detection of antigens (E. coli) by quantum dot (QD) based approach. Luminescent QD (CdTe) were synthesized by aqueous method and characterized using high resolution transmission electron microscopy (HRTEM), fluorescence spectroscopy and X-ray diffraction (XRD). The QDs were functionalized with anti-E. coli antibodies for immuno-detection. The reported process allowed easier and faster method of fabrication of circular 3D micochannels and demonstrated their potential use in an immuno-biosensor device. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. A mixed alkanethiol based immunosensor for surface plasmon field-enhanced fluorescence spectroscopy in serum.

    PubMed

    Scholten, Andreas; Menges, Bernhard; Juebner, Martin; Rothschild, Markus A; Bender, Katja

    2013-03-21

    This paper describes a simple and sensitive immuno-based biosensor for interference-reduced detection of C-reactive protein (CRP) in serum. The detection was performed by using a non-competitive sandwich immunoassay in combination with surface plasmon field-enhanced fluorescence spectroscopy (SPFS). CRP is an important marker for the diagnosis of inflammatory processes and cardiovascular diseases (CVD). It is nowadays detected by high-sensitivity enzyme-linked immunosorbent assays (ELISA) in blood serum. CRP was used as a model analyte in this work because it is well-characterized. However, interfering effects of matrix components affect the limit of detection (LOD) and quantification (LOQ) in general. Therefore, the availability of fast, sensitive and robust analytical methods is of major interest. A number of biosensor approaches have been described already, but only a few have demonstrated their usefulness in authentic samples such as serum. Thus our aim was to develop a simple and sensitive immunoassay-based biosensor for an interference-reduced detection of CRP in serum with surface plasmon enhanced fluorescence spectroscopy (SPFS). LODs and LOQs were experimentally determined both for CRP spiked buffer and serum. SPFS in combination with our biosensor allows sensitive analysis of CRP, achieving in buffer a LOD of 0.016 μg mL(-1) and a LOQ of 0.049 μg mL(-1). In serum the accomplished LOD was 0.026 μg mL(-1) and the LOQ was found to be 0.08 μg mL(-1). These low LODs and LOQs demonstrate the applicability of the designed biosensor for qualitative and semi-quantitative analysis of trace amounts of substances in very small sample volumes of body fluids.

  2. Multi-immunosensors based on electrolite-insulator-semiconductor structures for determination of some herbicides

    NASA Astrophysics Data System (ADS)

    Starodub, Nickolaj F.; Starodub, Valentyna M.; Krivenchuk, Vladimir E.; Shapovalenko, Valentyna F.

    2002-02-01

    New type of the multi-immune sensor was elaborated. It is based on electrolyte-insulator-semiconductors structures and intended for determination of such herbicides as simazine, atrazine and 2,4-D. The specific antibodies were immobilized on nitrocellulose disks, which were placed in measuring cells. The analysis was fulfilled by sequential saturation of antibodies, left unbound after their exposure to native herbicide in investigated sample, with labelled herbicide. If horse radish peroxidase (HRP) was used as label the sensitivity of this multi-immune sensor was about 5 and 1.25 (mu) g/L for simazine and 2,4-D, respectively. At the changing of HRP by (beta) -glucose oxidase the sensitivity of analysis of these herbicides increased approximately in 5 times. The linear plots of the registered concentrations were in the range of 1,0-150,0 and 0,25-150,0 ng/mL for simazine and 2,4-D respectively. It was recommended to use the developed immune sensor for wide screening of herbicides in environment. The ways for increasing of its sensitivity were proposed.

  3. Electrochemical immunosensor for detecting the spore wall protein of Nosema bombycis based on the amplification of hemin/G-quadruplex DNAzyme concatamers functionalized Pt@Pd nanowires.

    PubMed

    Wang, Qin; Song, Yue; Chai, Yaqin; Pan, Guoqing; Li, Tian; Yuan, Yali; Yuan, Ruo

    2014-10-15

    In this work, an ultrasensitive electrochemical immunosensor for detecting the Pebrine disease related spore wall protein of Nosema bombycis (SWP N.b) was fabricated based on the amplification of hemin/G-quadruplex functionalized Pt@Pd nanowires (Pt@PdNWs). The synthesized Pt@PdNWs possessed large surface area, which could effectively improve the immobilization amount of hemin/G-quadruplex DNAzyme concatamers produced via hybridization chain reaction (HCR). In the presence of SWP N.b, the hemin/G-quadruplex labeled Pt@PdNWs bioconjugations was captured on electrode surface and thus obtained electrochemical signal. After the addition of NADH into the electrolytic cell, hemin/G-quadruplex firstly acted as an NADH oxidase to locally produce H2O2 in the presence of dissolved O2. Then, the generated H2O2 would be quickly reduced via hemin/G-quadruplex as a horseradish peroxidase mimicking (HRP-mimicking) DNAzyme, which finally promoted the self-redox reaction of hemin/G-quadruplex and a greatly enhanced electrochemical signal was obtained. Furthermore, Pt@PdNWs with excellent electrocatalytic performance could also amplify electrochemical signal. With these amplification factors, the electrochemical immunosensor exhibited a wide linear range from 0.001 ng mL(-1) to 100 ng mL(-1) with a detection limit (LOD) of 0.24 pg mL(-1), providing a new promise for the diagnosis of Pebrine disease. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Love Wave Immunosensor for the Detection of Carbaryl Pesticide

    PubMed Central

    Rocha-Gaso, María-Isabel; García, José-Vicente; García, Pablo; March-Iborra, Carmen; Jiménez, Yolanda; Francis, Laurent-Alain; Montoya, Ángel; Arnau, Antonio

    2014-01-01

    A Love Wave (LW) immunosensor was developed for the detection of carbaryl pesticide. The experimental setup consisted on: a compact electronic characterization circuit based on phase and amplitude detection at constant frequency; an automated flow injection system; a thermal control unit; a custom-made flow-through cell; and Quartz/SiO2 LW sensors with a 40 μm wavelength and 120 MHz center frequency. The carbaryl detection was based on a competitive immunoassay format using LIB-CNH45 monoclonal antibody (MAb). Bovine Serum Albumin-CNH (BSA-CNH) carbaryl hapten-conjugate was covalently immobilized, via mercaptohexadecanoic acid self-assembled monolayer (SAM), onto the gold sensing area of the LW sensors. This immobilization allowed the reusability of the sensor for at least 70 assays without significant signal losses. The LW immunosensor showed a limit of detection (LOD) of 0.09 μg/L, a sensitivity of 0.31 μg/L and a linear working range of 0.14–1.63 μg/L. In comparison to other carbaryl immunosensors, the LW immunosensor achieved a high sensitivity and a low LOD. These features turn the LW immunosensor into a promising tool for applications that demand a high resolution, such as for the detection of pesticides in drinking water at European regulatory levels. PMID:25192313

  5. Love wave immunosensor for the detection of carbaryl pesticide.

    PubMed

    Rocha-Gaso, María-Isabel; García, José-Vicente; García, Pablo; March-Iborra, Carmen; Jiménez, Yolanda; Francis, Laurent-Alain; Montoya, Angel; Arnau, Antonio

    2014-09-03

    A Love Wave (LW) immunosensor was developed for the detection of carbaryl pesticide. The experimental setup consisted on: a compact electronic characterization circuit based on phase and amplitude detection at constant frequency; an automated flow injection system; a thermal control unit; a custom-made flow-through cell; and Quartz /SiO2 LW sensors with a 40 μm wavelength and 120 MHz center frequency. The carbaryl detection was based on a competitive immunoassay format using LIB-CNH45 monoclonal antibody (MAb). Bovine Serum Albumin-CNH (BSA-CNH) carbaryl hapten-conjugate was covalently immobilized, via mercaptohexadecanoic acid self-assembled monolayer (SAM), onto the gold sensing area of the LW sensors. This immobilization allowed the reusability of the sensor for at least 70 assays without significant signal losses. The LW immunosensor showed a limit of detection (LOD) of 0.09 μg/L, a sensitivity of 0.31 μg/L and a linear working range of 0.14-1.63 μg/L. In comparison to other carbaryl immunosensors, the LW immunosensor achieved a high sensitivity and a low LOD. These features turn the LW immunosensor into a promising tool for applications that demand a high resolution, such as for the detection of pesticides in drinking water at European regulatory levels.

  6. An immunosensor based on magnetic relaxation switch and polystyrene microparticle-induced immune multivalency enrichment system for the detection of Pantoea stewartii subsp. Stewartii.

    PubMed

    Chen, Yi ping; Zou, Ming qiang; Wang, Da ning; Li, Yong liang; Xue, Qiang; Xie, Meng xia; Qi, Cai

    2013-05-15

    A rapid, sensitive, and simple immunosensor has been developed for the detection of Pantoea stewartii subsp. Stewartii (Pss). This immunosensor combines magnetic relaxation switch (MRS) assay with polystyrene microparticle-induced immune multivalency enrichment system. Comparing to conventional enzyme-linked immunosorbent assay (ELISA), the immunosensor developed in this study provides higher sensitivity and requires less analysis time. The detection limit of Pss obtained by immunosensor was determined to be 10(3)cfu/mL, 50 times lower than that by ELISA (5×10(4)cfu/mL), while the analysis time required by immunosensor is 30min much shorter than that by ELISA. The average recoveries studied with Pss at various spiking levels ranged from 85.5% to 93.4% with a relative standard deviation (RSD) below 6.0%. No cross-reaction with the other five strains was found, demonstrating a good specificity of Pss detection. The results showed that the MRS immunosensor combined with PS-induced immune multivalency enhancement system is a promising platform for the determination of large biological molecules due to its high sensitivity, specificity, homogeneity, and speed. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. A novel antibody-antigen based impedimetric immunosensor for low level detection of HER2 in serum samples of breast cancer patients via modification of a gold nanoparticles decorated multiwall carbon nanotube-ionic liquid electrode.

    PubMed

    Arkan, Elham; Saber, Reza; Karimi, Ziba; Shamsipur, Mojtaba

    2015-05-18

    A highly sensitive impedimetric immunosensor based on a gold nanoparticles/multiwall carbon nanotube-ionic liquid electrode (AuNPs/MW-CILE) was developed for the determination of human epidermal growth factor receptor 2 (HER2). Gold nanoparticles were used to enhance the extent of immobilization and to retain the immunoactivity of the antibody Herceptin on the electrode. Cyclic voltammetry and electrochemical impedance spectroscopy were employed for characterization of various layers coated onto the AuNPs/MW-CILE. The impedance measurements at different steps were based on the charge transfer kinetics of the [Fe(CN)6](3-/4-) redox pair. The immobilization of antibody and the corresponding antigen-antibody interaction at the electrode surface altered the interfacial electron transfer. The interactions of antibody with various concentrations of antigen were also monitored via the change of impedance response. The results showed that the charge transfer resistance increases linearly with increasing concentrations of HER2 antigen. The linear range and limit of detection were found as 10-110 ng mL(-1) and 7.4 ng mL(-1), respectively. The sensitivity and specificity of the immunosensor were validated. The results showed that the prepared immunosensor is a useful tool for screening of trace amounts of HER2 in serum samples of breast cancer patients. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Multiwall carbon nanotube-ionic liquid electrode modified with gold nanoparticles as a base for preparation of a novel impedimetric immunosensor for low level detection of human serum albumin in biological fluids.

    PubMed

    Arkan, Elham; Saber, Reza; Karimi, Ziba; Mostafaie, Ali; Shamsipur, Mojtaba

    2014-04-01

    A highly sensitive ionic liquid-multiwall carbon nanotube based impedimetric immunosensor modified with gold nanoparticles (GNPs) was developed for the determination of human serum albumin (HSA). The antigen and antibody models used were HSA and activated anti-HSA, respectively. GNPs were electrodeposited on the multiwall based carbon ionic liquid electrode (MW-CILE) surface and then colloidal GNPs were coated through the thiol groups of 1,6-hexanedithiol (HDT) monolayer as a cross linker. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed for characterization of the various layers coated onto the electrode. The electron transfer resistance (Ret) of the antibody-modified electrode changed linearly with the concentration of HSA. The linear range and limit of detection were 0.1-100μgmL(-1) and 15.4ngmL(-1), respectively. The sensitivity and specificity of the immunosensor were validated using human urine and human serum samples. The results showed that the prepared immunosensor is a useful tool for screening trace amounts of HSA in the biological fluids of proteinuria and diabetics patients, in clinical laboratories. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Sensitive ECL immunosensor for detection of retinol-binding protein based on double-assisted signal amplification strategy of multiwalled carbon nanotubes and Ru(bpy)3(2+) doped mesoporous silica nanospheres.

    PubMed

    Wu, Beina; Hu, Chenyi; Hu, Xiaoqing; Cao, Hongmei; Huang, Chusen; Shen, Hebai; Jia, Nengqin

    2013-12-15

    A novel electrochemiluminescence (ECL) strategy based on the sandwich-type immunosensor for sensitive detection of retinol-binding protein (RBP) was developed. The primary antibody anti-RBP was immobilized onto multiwalled carbon nanotubes (MWCNTs), which have large surface area and high electrical conductivity. The RBP antigen and Ru-Nafion@SiO2-labeled secondary antibody were then successively conjugated to form sandwich-type immunocomplexes through the specific interaction between antigen and antibody. The ECL signal amplification was significantly improved due to the synergistic effect of MWCNTs and mesoporous silica nanospheres (mSiO2). The developed ECL immunosensor exhibited high sensitivity and specificity for the detection of RBP and responded linearly to the clinically-relevant concentration of RBP from 78 to 5000 ng mL(-1). Moreover, the MWCNT-based ECL immunosensor displayed excellent stability and reproducibility, as well as successfully achieved the detection of RBP in patient urine samples with desirable results. The present work provided a promising technique for the clinical screening of RBP and point-of-care diagnostics.

  10. The sandwich-type electrochemiluminescence immunosensor for α-fetoprotein based on enrichment by Fe3O4-Au magnetic nano probes and signal amplification by CdS-Au composite nanoparticles labeled anti-AFP.

    PubMed

    Zhou, Hankun; Gan, Ning; Li, Tianhua; Cao, Yuting; Zeng, Saolin; Zheng, Lei; Guo, Zhiyong

    2012-10-09

    A novel and sensitive sandwich-type electrochemiluminescence (ECL) immunosensor was fabricated on a glassy carbon electrode (GCE) for ultra trace levels of α-fetoprotein (AFP) based on sandwich immunoreaction strategy by enrichment using magnetic capture probes and quantum dots coated with Au shell (CdS-Au) as the signal tag. The capture probe was prepared by immobilizing the primary antibody of AFP (Ab1) on the core/shell Fe(3)O(4)-Au nanoparticles, which was first employed to capture AFP antigens to form Fe(3)O(4)-Au/Ab1/AFP complex from the serum after incubation. The product can be separated from the background solution through the magnetic separation. Then the CdS-Au labeled secondary antibody (Ab2) as signal tag (CdS-Au/Ab2) was conjugated successfully with Fe(3)O(4)-Au/Ab1/AFP complex to form a sandwich-type immunocomplex (Fe(3)O(4)-Au/Ab1/AFP/Ab2/CdS-Au), which can be further separated by an external magnetic field and produce ECL signals at a fixed voltage. The signal was proportional to a certain concentration range of AFP for quantification. Thus, an easy-to-use immunosensor with magnetic probes and a quantum dots signal tag was obtained. The immunosensor performed at a level of high sensitivity and a broad concentration range for AFP between 0.0005 and 5.0 ng mL(-1) with a detection limit of 0.2 pg mL(-1). The use of magnetic probes was combined with pre-concentration and separation for trace levels of tumor markers in the serum. Due to the amplification of the signal tag, the immunosensor is highly sensitive, which can offer great promise for rapid, simple, selective and cost-effective detection of effective biomonitoring for clinical application.

  11. Photocatalytic silver enhancement reaction for gravimetric immunosensors.

    PubMed

    Seo, Hyejung; Joo, Jinmyoung; Ko, Wooree; Jung, Namchul; Jeon, Sangmin

    2010-12-17

    A novel microgravimetric immunosensor has been developed using TiO(2) nanoparticle-modified immunoassay and silver enhancement reaction. An antibody-conjugated TiO(2) nanoparticle is bound to the AFP antigen immobilized on a quartz resonator. When the nanoparticles are exposed to UV light in a silver nitrate solution, the photocatalytic reduction of silver ions results in the formation of metallic silver onto the nanoparticles and induces a decrease in the resonance frequency. The frequency change by this photocatalytic reduction reaction is three orders of magnitude larger than the change by antigen binding alone. The efficiency of the photocatalytic reaction has been found to increase with the fraction of anatase crystallites in the nanoparticles and the concentration of the AgNO(3) solution. The results highlight the potential of the photocatalytic nanoparticles for the detection of low concentrations of target molecules using gravimetric sensors.

  12. Photocatalytic silver enhancement reaction for gravimetric immunosensors

    NASA Astrophysics Data System (ADS)

    Seo, Hyejung; Joo, Jinmyoung; Ko, Wooree; Jung, Namchul; Jeon, Sangmin

    2010-12-01

    A novel microgravimetric immunosensor has been developed using TiO2 nanoparticle-modified immunoassay and silver enhancement reaction. An antibody-conjugated TiO2 nanoparticle is bound to the AFP antigen immobilized on a quartz resonator. When the nanoparticles are exposed to UV light in a silver nitrate solution, the photocatalytic reduction of silver ions results in the formation of metallic silver onto the nanoparticles and induces a decrease in the resonance frequency. The frequency change by this photocatalytic reduction reaction is three orders of magnitude larger than the change by antigen binding alone. The efficiency of the photocatalytic reaction has been found to increase with the fraction of anatase crystallites in the nanoparticles and the concentration of the AgNO3 solution. The results highlight the potential of the photocatalytic nanoparticles for the detection of low concentrations of target molecules using gravimetric sensors.

  13. Dopamine modified hyperbranched TiO2 arrays based ultrasensitive photoelectrochemical immunosensor for detecting neuron specific enolase.

    PubMed

    Li, He; Xiao, Qiyou; Lv, Jiaxin; Lei, Qin; Huang, Yujie

    2017-08-15

    In this work, three-dimensional (3D) hyperbranched TiO2 nanorod arrays were synthesized and used to fabricate dopamine sensitized photoelectrochemical (PEC) biosensor. To increase the lifetime of charge carriers and enhance the photocurrent responses signal, a delicate signal amplification strategy by introducing dopamine (DA) as sensitizer was developed. The dopamine sensitized TiO2 can shorten the carrier diffusion distance, improve light harvesting efficiency and charge collection efficiency, which results in performance improvement of the as-obtained PEC sensor. This proposed biosensor for determination of neuron specific enolase (NSE) demonstrated a good linear relationship range from 0.1 ng mL(-1) to 1000 ng mL(-1) with a detection limit of 0.05 ngmL(-1) (S/N = 3). In addition, the as-prepared immunosensor exhibits excellent selectivity, stability and reproducibility, which could be extended to other label-free sensing fields. Therefore, this proposed method may also provide potential applications for the clinical examination. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. An impedance immunosensor based on low-cost microelectrodes and specific monoclonal antibodies for rapid detection of avian influenza virus H5N1 in chicken swabs.

    PubMed

    Lin, Jianhan; Wang, Ronghui; Jiao, Peirong; Li, Yuntao; Li, Yanbin; Liao, Min; Yu, Yude; Wang, Maohua

    2015-05-15

    Early screening of suspected cases is the key to control the spread of avian influenza (AI) H5N1. In our previous studies, an impedance biosensor with an interdigitated array microelectrode based biochip was developed and validated with pure AI H5 virus, but had limitations in cost and reliability of the biochip, specificity of the antibody against Asian in-field H5N1 virus and detection of H5N1 virus in real samples. The purpose of this study is to develop a low-cost impedance immunosensor for rapid detection of Asian in-field AI H5N1 virus in chicken swabs within 1h and validate it with the H5N1 virus. Specific monoclonal antibodies against AI H5N1 virus were developed by fusion of mouse myeloma cells with spleen cells isolated from an H5N1-virus-immunized mouse. Dot-ELISA analysis demonstrated that the developed antibodies had good affinity and specificity with the H5N1 virus. The microelectrodes were redesigned with compact size, fabricated using an improved wet-etching micro-fabrication process with a higher qualified production rate of 70-80%, and modified with the antibodies by the Protein A method. Equivalent circuit analysis indicated that electron transfer resistor was effective with the increase in impedance after capturing of the H5N1 viruses. Linear relationship between impedance change and logarithmic value of H5N1 virus at the concentrations from 2(-1) to 2(4) HAU/50 μl was found and the lower limit of detection was 2(-1) HAU/50 μl. No obvious interferences from non-target viruses such as H6N2, H9N2, Newcastle disease virus, and infectious bronchitis virus were found. Chicken swab tests showed that the impedance immunosensor had a comparable accuracy with real-time RT-PCR compared to viral isolation.

  15. Recent Advances in Electrochemical Immunosensors.

    PubMed

    Piro, Benoît; Reisberg, Steeve

    2017-04-07

    Immunosensors have experienced a very significant growth in recent years, driven by the need for fast, sensitive, portable and easy-to-use devices to detect biomarkers for clinical diagnosis or to monitor organic pollutants in natural or industrial environments. Advances in the field of signal amplification using enzymatic reactions, nanomaterials such as carbon nanotubes, graphene and graphene derivatives, metallic nanoparticles (gold, silver, various oxides or metal complexes), or magnetic beads show how it is possible to improve collection, binding or transduction performances and reach the requirements for realistic clinical diagnostic or environmental control. This review presents these most recent advances; it focuses first on classical electrode substrates, then moves to carbon-based nanostructured ones including carbon nanotubes, graphene and other carbon materials, metal or metal-oxide nanoparticles, magnetic nanoparticles, dendrimers and, to finish, explore the use of ionic liquids. Analytical performances are systematically covered and compared, depending on the detection principle, but also from a chronological perspective, from 2012 to 2016 and early 2017.

  16. Recent Advances in Electrochemical Immunosensors

    PubMed Central

    Piro, Benoît; Reisberg, Steeve

    2017-01-01

    Immunosensors have experienced a very significant growth in recent years, driven by the need for fast, sensitive, portable and easy-to-use devices to detect biomarkers for clinical diagnosis or to monitor organic pollutants in natural or industrial environments. Advances in the field of signal amplification using enzymatic reactions, nanomaterials such as carbon nanotubes, graphene and graphene derivatives, metallic nanoparticles (gold, silver, various oxides or metal complexes), or magnetic beads show how it is possible to improve collection, binding or transduction performances and reach the requirements for realistic clinical diagnostic or environmental control. This review presents these most recent advances; it focuses first on classical electrode substrates, then moves to carbon-based nanostructured ones including carbon nanotubes, graphene and other carbon materials, metal or metal-oxide nanoparticles, magnetic nanoparticles, dendrimers and, to finish, explore the use of ionic liquids. Analytical performances are systematically covered and compared, depending on the detection principle, but also from a chronological perspective, from 2012 to 2016 and early 2017. PMID:28387718

  17. Self-enhanced N-(aminobutyl)-N-(ethylisoluminol) derivative-based electrochemiluminescence immunosensor for sensitive laminin detection using PdIr cubes as a mimic peroxidase

    NASA Astrophysics Data System (ADS)

    Jiang, Xinya; Wang, Huijun; Wang, Haijun; Zhuo, Ying; Yuan, Ruo; Chai, Yaqin

    2016-04-01

    Herein, a self-enhanced N-(aminobutyl)-N-(ethylisoluminol) (ABEI) derivative-based electrochemiluminescence (ECL) immunosensor was constructed for the determination of laminin (LN) using PdIr cubes as a mimic peroxidase for signal amplification. Initially, PdIr cubes with efficient peroxidase mimicking properties, large specific surface areas, and good stability and uniformity were synthesized. Then, l-cysteine (l-Cys) and ABEI were immobilized on the PdIr cubes to form the self-enhanced ECL nanocomplex (PdIr-l-Cys-ABEI). In this nanocomplex, PdIr cubes, whose catalytic constant is higher than that of horseradish peroxidase (HRP), could effectively catalyze H2O2 decomposition and thus enhance the ECL intensity of ABEI. Moreover, PdIr cubes can be easily modified with functional groups, which make them adaptable to desired supported platforms. On the other hand, l-Cys as a coreactant of ABEI could effectively enhance the luminous efficiency due to the intramolecular ECL reaction which could reduce the energy loss between l-Cys and ABEI by giving a shorter electron transfer distance. The developed strategy combined an ABEI derivative as a self-enhanced ECL luminophore and PdIr cubes as a mimic peroxidase, resulting in a significantly enhanced ECL signal output. Also, the strategy showed high sensitivity and selectivity for LN, which suggested that our new approach could be potentially applied in monitoring different proteins.

  18. A cytokine immunosensor for Multiple Sclerosis detection based upon label-free electrochemical impedance spectroscopy using electroplated printed circuit board electrodes.

    PubMed

    Bhavsar, Kinjal; Fairchild, Aaron; Alonas, Eric; Bishop, Daniel K; La Belle, Jeffrey T; Sweeney, James; Alford, T L; Joshi, Lokesh

    2009-10-15

    A biosensor for the serum cytokine, Interleukin-12 (IL-12), based upon a label-free electrochemical impedance spectroscopy (EIS) monitoring approach is described. Overexpression of IL-12 has been correlated to the diagnosis of Multiple Sclerosis (MS). An immunosensor has been fabricated by electroplating gold onto a disposable printed circuit board (PCB) electrode and immobilizing anti-IL-12 monoclonal antibodies (MAb) onto the surface of the electrode. This approach yields a robust sensor that facilitates reproducible mass fabrication and easy alteration of the electrode shape. Results indicate that this novel PCB sensor can detect IL-12 at physiological levels, <100 fM with f-values of 0.05 (typically <0.0001) in a label-free and rapid manner. A linear (with respect to log concentration) detectable range was achieved. Detection in a complex biological solution is also explored; however, significant loss of dynamic range is noted in the 100% complex solution. The cost effective approach described here can be used potentially for diagnosis of diseases (like MS) with known biomarkers in body fluids and for monitoring physiological levels of biomolecules with healthcare, food, and environmental relevance.

  19. A sensitive and disposable indium tin oxide based electrochemical immunosensor for label-free detection of MAGE-1.

    PubMed

    Demirbakan, Burçak; Sezgintürk, Mustafa Kemal

    2017-07-01

    MAGE-1 (MAGE, for melanoma antigen), was identified by virtue of its processing and cell surface expression as a tumor-specific peptide bound to major histocompatibility complexes which was reactive with autolytic T cells. 3-Glycidoxypropyltrimethoxysilane (3-GOPS) is frequently employed for the preparation of dense heterometal hybrid polymers which are used, e.g., for hard coatings of organic polymers and contact lens materials in the optical industry. In this study, we have improved a new immunological biosensor with indium tin oxide (ITO). Then, Anti-MAGE-1 antibody was covalently immobilized with 3-GOPS which formed a self-assembled monolayers (SAMs) on modified ITO electrodes. Analytical characteristics such as square wave voltammetry, linear determination range, repeatability, reproducibility and regeneration of biosensors are determined. All characterization steps are monitored by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV). The developed biosensor has wide determination range (0.5fg-15fg/mL). To investigate long shelf life of the fabricated biosensor, the immunosensors were stored at 4°C for periods ten weeks. Futhermore, binding kinetics of MAGE1 to antiMAGE-1 is monitored by single frequency technique in real time. Additionally, Kramer's-Kronig transform was used to understand whether the impedance spectra of biosensor system are affected from the variation that occurred because of external factor. Morphological characteristics of constructed biosensor were observed by scanning electron microscopy. Real human serum samples were also analyzed by the proposed biosensor, successfully. A commercial ELISA kit was also used as a reference method to validate the results obtained by the biosensor. Finally, this biosensor was tried in real blood sample and that showed it could be utilized in clinical applications. This biosensor can be preferred due to it has a wide linear range and it can be prepared easily.

  20. Novel fiber optic immunosensor instrument

    NASA Astrophysics Data System (ADS)

    Wang, Zhiyu; Huang, Wenling; Tang, Lei; Zhou, Bo; Li, Yugi; He, Jun

    1996-09-01

    It has developed and performed a novel fiberoptic immunosensor instrument with operating wavelength 400 - 760 nm and repeatability cv equals 0.27%. The instrument has many excellent features such as simplified operation, faster testing time, higher sensitivity and economic cost. It has completely eliminated recovery period which traditional immunosensor owned due to use separative sensor structure. It can widely apply to test for bacteria, virus, hormone, parasite and cancer protein in clinical examination. The instrument has operated in laboratory and relevant medicine units and successfully tested monoclonal rat-anti-human of 413 cases in clinic and prepared with existing ELISA method, the coincidence probability reached 94 to 100%.

  1. DIRECT ELECTROCHEMICAL IMMUNOSENSOR FOR POLYCHLORINATED BIPHENYLS. (R825323)

    EPA Science Inventory

    A direct electrochemical immunosensor has been developed for the determination of polychlorinated biphenyls (PCBs) in water. The assay is based on the measurement of the current due to the specific binding between PCB and anti-PCB antibody-immobilized conducting polymer matrix. T...

  2. DIRECT ELECTROCHEMICAL IMMUNOSENSOR FOR POLYCHLORINATED BIPHENYLS. (R825323)

    EPA Science Inventory

    A direct electrochemical immunosensor has been developed for the determination of polychlorinated biphenyls (PCBs) in water. The assay is based on the measurement of the current due to the specific binding between PCB and anti-PCB antibody-immobilized conducting polymer matrix. T...

  3. Continuous flow immunosensor for highly selective and real-time detection of sub-ppb levels of 2-hydroxybiphenyl by using surface plasmon resonance imaging.

    PubMed

    Gobi, K Vengatajalabathy; Tanaka, Hiroyuki; Shoyama, Yukihiro; Miura, Norio

    2004-09-15

    A biosensor based on surface plasmon resonance (SPR) is developed for the detection of 2-hydroxybiphenyl (HBP). A monoclonal antibody against HBP (abbreviated hereafter as HBP-mAb) is developed and used for the detection of HBP by competitive SPR-based immunoassay and enzyme linked immunosorbent assay (ELISA) methods. A novel HBP-hapten compound, HBP-bovine serum albumin conjugate (HBP-BSA), derived by binding several HBP units with BSA by an aliphatic chain spacer is used in the development of antibody and for the functionalization of immunoprobes. HBP-BSA linked to the Au surface of the SPR sensor chip undergoes inhibitive immunoreaction with HBP-mAb in the presence of free HBP. The SPR-based immunoassay provides a rapid determination (response time: approximately 20 min) of the concentration of HBP in the range of 0.1-1000 ppb (ng/ml). Regeneration of the sensor chip is gained by treating the antibody-anchored SPR sensor chip with a pepsin solution (100 ppm (microg/ml); pH 2.0) for few minutes. The SPR sensor chip is reusable for the detection of HBP for more than 20 cycles with average loss of 0.35% reactivity per regeneration step. HBP concentration is determined as low as 0.1 and 3 ppb using the SPR sensor and ELISA measurements, respectively. The developed SPR sensor for HBP is free from interference by coexisting benzo[a]pyrene (BaP), 2,4-dichlorophenoxyacetic acid (2,4-D) and benz[a]anthracene; SPR angle shift obtained to the flow of HBP is almost same irrespective to the presence or absence of a same concentration of these carcinogenic polycyclic aromatic hydrocarbons together. The SPR sensor for HBP is proved to be applicable in simultaneous detection of HBP and BaP in parallel with another SPR sensor for BaP.

  4. Electrochemical immunosensor for interferon-γ based on disposable ITO detector and HRP-antibody-conjugated nano gold as signal tag.

    PubMed

    Zhang, Yaru; Zhang, Bin; Ye, Xiaoli; Yan, Yuqi; Huang, Langhuan; Jiang, Zhenyou; Tan, Shaozao; Cai, Xiang

    2016-02-01

    Tuberculosis is the most frequent cause of infection-related death worldwide. A new disposable electrochemical immunosensor with low cost and simple fabrication was proposed to detect interferon-γ (IFN-γ). Diallyldimethylammonium chloride (PDDA) and Au nanoparticle (AuNP) composite were used to provide an efficient biointerface, horseradish peroxidase (HRP)-labeled antibody-conjugated AuNP (HRP-Ab2-AuNP) bioconjugates were used as a novel signal tag. The large amounts of HRP on the signal tag can catalyze the oxidation of Hydroquinone (HQ) by H2O2, which can induce an amplified reductive current. The catalytic reduction current was related to the amount of HRP immobilized on the surface, which itself was related to the concentration of IFN-γ. Under optimized conditions, the proposed immunosensor showed a high sensitivity and a linear range of 0.1-10,000pg/mL with a detection limit of 0.048pg/mL. The assay results of clinical serum samples obtained by the immunosensor were in acceptable agreement with the reference values. Therefore, the immunosensor possessed excellent clinical value in early diagnosis and control of tuberculosis. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

  5. A Nano-Au/C-MWCNT based label free amperometric immunosensor for the detection of capsicum chlorosis virus in bell pepper.

    PubMed

    Sharma, Anshul; Kaushal, Ankur; Kulshrestha, Saurabh

    2017-03-14

    Accurate and on time diagnosis of plant viruses is an essential prerequisite for efficient control in field conditions. A number of diagnostic methods have been reported with the required level of sensitivity. Here, we propose a label free immunosensor for efficient and sensitive detection of capsicum chlorosis virus (CaCV) in bell pepper. Antigen was immobilized over the surface of gold nanoparticle/multi-walled carbon nanotube (Nano-Au/C-MWCNT) screen printed electrodes using 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)/N-hydroxysuccinimide (NHS) cross linking chemistry followed by interaction with groundnut bud necrosis virus (GBNV)/CaCV specific polyclonal antibody. The electrochemical response was measured by cyclic voltammetry (CV), differential pulse voltammetry (DPV) using the redox indicator. Electrode surface characterization was done by performing scanning electron microscopy (SEM). Electrochemical studies showed positive results at different antigenic dilutions ranging from 10(-2) - 8x10(-5). The sensitivity of the immunosensor developed has been compared with direct antigen coated enzyme-linked immunosorbent assay (DAC-ELISA) and the results showed that the immunosensor developed was 800-1000 times more sensitive, when compared to DAC-ELISA for CaCV detection. The immunosensor we have developed is economical and sensitive and could be used for immediate determination of the presence of virus in extracts from bell pepper leaves.

  6. A competitive electrochemical immunosensor for the detection of human interleukin-6 based on the electrically heated carbon electrode and silver nanoparticles functionalized labels.

    PubMed

    Lou, Yongbing; He, Tingting; Jiang, Fang; Shi, Jian-Jun; Zhu, Jun-Jie

    2014-05-01

    A facile one-step electrochemical reduction method was developed to prepare electrochemically reduced graphene oxide (ERGO) and gold-palladium bimetallic nanoparticles (AuPdNPs) as the platform of immunosensor. A novel competitive electrochemical immunosensor was then proposed by combining the ERGO-AuPdNPs platform with silver nanoparticles (AgNPs) functionalized polystyrene bionanolabel for the sensitive detection of human interleukin-6 (IL-6). An electrically heated carbon electrode (HCPE) was introduced in the detection procedure of the immunosensor, and further improved the sensitivity. The immunosensor exhibited a wide linear response to IL-6 ranging from 0.1 to 100000 pg mL(-1) with a detection limit of 0.059 pg mL(-1). The proposed method showed good precision, broad linear range, acceptable stability and high reproducibility, and could be used for the detection of IL-6 in real samples, which possessed promising application in clinical research. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Electrochemical impedance immunosensor based on gold nanoparticles-protein G for the detection of cancer marker epidermal growth factor receptor in human plasma and brain tissue.

    PubMed

    Elshafey, Reda; Tavares, Ana C; Siaj, Mohamed; Zourob, Mohammed

    2013-12-15

    A sensitive label-free impedimetric immunosensor for the detection of cancer biomarker epidermal growth factor receptor (EGFR) was developed with a limit of detection as low as 0.34 pg mL(-1) in PBS and 0.88 pg mL(-1) in human plasma. The gold nanoparticles were electrodeposited to modify the gold surface and to increase the electrochemical active area by a factor of approximately 3, i.e. by 68%. Protein G was used as scaffold for well oriented EGFR antibodies immobilization. Under optimal experimental parameters, the impedance changes were used for the detection of EGFR with a wide dynamic range of 1 pg mL(-1)-1 μg mL(-1). The immunosensor showed an excellent reproducibility and selectivity against biomarkers, murine double minute 2 and platelet derived growth factor receptor. The excellent analytical performance of the EGFR immunosensor in terms of selectivity, sensitivity and low detection limit might be attributed to the synergetic effect between the Au nanoparticles and the protein G scaffold. The matrix effect from mouse brain tissue homogenate was also studied and the immunosensor showed excellent recoveries ranging from 98.3% to 115% and RSD of 1.55-6.17. Finally, our developed strategy could open new avenues for clinical screening and prognosis of tumors. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Amperometric immunosensor for α-fetoprotein antigen in human serum based on co-immobilizing dinuclear copper complex and gold nanoparticle doped chitosan film

    NASA Astrophysics Data System (ADS)

    Gan, Ning; Meng, Ling Hua; Wang, Feng

    2009-09-01

    A sensitive amperometric immunosensor for α-fetoprotein (AFP), a tumor marker for the diagnosis of hepatocellular carcinoma (HCC), was constructed, The immunosensor is prepared by co-immobilizing [Cu2(phen)2Cl2] (μ-Cl)2 (CuL), nano-Au/Chitosan(Chit) composite, horseradish peroxidase (HRP) and AFP antibody(anti-AFP) on a glassy carbon electrode (GCE). Firstly, CuL was irreversibly absorb on GCE electrode through π-π stacking interaction; then nano-Au/Chit composite was immobilized onto the electrode because of its excellent membrane-forming ability, finally HRP and anti-AFP was adsorbed onto the surface of the gold nanoparticles to construct GCE | CuL/nanoAu-chit/HRP/anti-AFP immunosensor. The preparation procedure of the electrode was characterized by electrochemical and spectroscopy method. The results showed that this immunosensor exhibited an excellent electrocatalytic response to the reduction of hydrogen peroxide (H2O2) without the aid of an electron mediator, offers a high-sensitivity (1710 nA · ng-1 · ml-1) for the detection of AFP and has good correlation for detection of AFP in the range of 0.2 to 120.0 ng/ml with a detection limit of 0.05 ng/ml. The biosensor showed high selectivity as well as good stability and reproductivity.

  9. Ultrasensitive amperometric immunosensor for PSA detection based on Cu2O@CeO2-Au nanocomposites as integrated triple signal amplification strategy.

    PubMed

    Li, Faying; Li, Yueyun; Feng, Jinhui; Dong, Yunhui; Wang, Ping; Chen, Lei; Chen, Zhiwei; Liu, Hui; Wei, Qin

    2017-01-15

    In this work, a novel label-free electrochemical immunosensor was developed for the quantitative detection of prostate specific antigen (PSA). To this end, the amino functionalized cuprous oxide @ ceric dioxide (Cu2O@CeO2-NH2) core-shell nanocomposites were prepared to bond gold nanoparticles (Au NPs) by constructing stable Au-N bond between Au NPs and -NH2. Because the synergetic effect presents in Cu2O@CeO2 core-shell loaded with Au NPs (Cu2O@CeO2-Au), it shows better electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2) than single Cu2O, Au NPs and Cu2O@CeO2. Featured by large specific surface area, good biocompatibility and good electrochemical properties which can greatly improve the electronic transmission rate, Cu2O@CeO2-Au was used as transducing materials to achieve efficiently capture antibodies and triple signal amplification of the proposed immunosensor. Under the optimal conditions, the proposed immunosensor exhibited a wide linear range from 0.1pg/mL to 100ng/mL with a low detection limit of 0.03pg/mL (S/N=3). Furthermore, the proposed label-free immunosensor has been used to determine PSA in human serum with satisfactory results. Meanwhile, it displayed good reproducibility, acceptable selectivity, and long-term stability, which had promising application in bioassay analysis.

  10. Nanoelectrochemical Immunosensors for Protein Detection

    NASA Astrophysics Data System (ADS)

    Carpentiero, Alessandro; de Leo, Manuela; Garcia Romero, Ivan; Pozzi Mucelli, Stefano; Reuther, Freimut; Stanta, Giorgio; Tormen, Massimo; Ugo, Paolo; Zamuner, Martina

    Nanoelectrochemical immunosensors fabricated by templated electrodeposition of gold nanoelectrodes inside the pores of polycarbonate (PC) track-etched membranes, followed by the immobilization of the biorecognition elements on the surrounding PC, have proven high sensitivity and specificity for protein detection. The signal transduction scheme involves a suitable redox mediator added to the sample solution to shuttle electrons from the gold nanoelectrodes to the biorecognition layer, both elements being in strict spatial proximity. Highly improved signal-to-background current ratio, which are peculiar of NEEs with respect to other electrochemical transducers, can be exploited in this way. Two detection schemes were tested: one based on the direct immobilization of the target protein on the PC of the NEE (approach A) and the other based on the immobilisation on PC of an antibody to capture the target protein (approach B). The biorecognition process was completed by adding a primary antibody and a secondary antibody with horse radish peroxidase (HRP) as enzyme label; methylene blue was the redox mediator added to the electrolyte solution. Typical target analytes were single chain fragment variable proteins, for approach A, and trastuzumab (also known as Herceptin®), for approach B. NEE-based capture sensors were tested successfully to detect small amounts of the receptor protein HER2 in biological samples. Finally, motivated by the target of a better control of the geometrical characteristics of ensembles of nanoelectrodes (size, density, geometrical arrangement, and degree of recession), and by the positive results obtained with track-etch membranes of PC from the standpoint of protein immobilization, we demonstrated the fabrication of nanobiosensors by patterning ordered arrays of nanoelectrodes (NEAs) by electron beam lithography (EBL) on polycarbonate. EBL results perfectly suitable for the top-down fabrication of arrays of nanobiosensors on thin PC films

  11. Label-Free Chemiresistive Immunosensors for Viruses

    PubMed Central

    Shirale, Dhammanand J.; Bangar, Mangesh A.; Park, Miso; Yates, Marylynn V.; Chen, Wilfred; Myung, Nosang V.

    2012-01-01

    We report development, characterization and testing of chemiresistive immunosensors based on single polypyrrole (Ppy) nanowire for highly sensitive, specific, label free, and direct detection of viruses. Bacteriophages T7 and MS2 were used as safe models for viruses for demonstration. Ppy nanowires were electrochemically polymerized into alumina template and single nanowire based devices were assembled on a pair of gold electrodes by ac dielectrophoretic alignment and anchored using maskless electrodeposition. Anti-T7 or anti-MS2 antibodies were immobilized on single Ppy nanowire using EDC-NHS chemistry to fabricate nano-biosensor for the detection of corresponding bacteriophage. The biosensors showed excellent sensitivity with a lower detection limit of 10−3 plaque forming unit (PFU) in 10 mM phosphate buffer, wide dynamic range and excellent selectivity. The immunosensors were successfully applied for the detection of phages in spiked untreated lake water samples. The results show the potential of these sensors in health care, environmental monitoring, food safety and homeland security for sensitive, specific, rapid and affordable detection of bioagents/pathogens. PMID:21058664

  12. Photoelectrochemical immunosensor for methylated RNA detection based on g-C3N4/CdS quantum dots heterojunction and Phos-tag-biotin.

    PubMed

    Wang, Haiyan; Zhang, Qihai; Yin, Huanshun; Wang, Minghui; Jiang, Wenjing; Ai, Shiyun

    2017-09-15

    N(6)-methyladenosine (m(6)A) is an enigmatic and abundant internal modification in eukaryotic messenger RNA (mRNA), which could affect various aspects of RNA metabolism and mRNA translation. Herein, a novel photoelectrochemical (PEC) immunosensor was constructed for m(6)A detection based on the inhibition of Cu(2+) to the photoactivity of g-C3N4/CdS quantum dots (g-C3N4/CdS) heterojunction, where g-C3N4/CdS heterojunction was used as photoactive material, anti-m(6)A antibody as recognition unit for m(6)A-containing RNA, Phos-tag-biotin as link unit and avidin functionalized CuO as PEC signal indicator. When CuO was captured on electrode through biotin-avidin affinity reaction and then treated with HCl, Cu(2+) could be released and CuxS would be formed based on the selective interaction between CdS and Cu(2+), leading the photocurrent obviously decreased. Under the optimal detection conditions, the PEC biosensor displayed a linear range of 0.01-10nM and a low detection limit of 3.53 pM for methylated RNA determination. Furthermore, the developed method could also be used to detect the expression level of m(6)A methylated RNA in serum samples of breast cancer patient before and after operative treatment. The proposed assay strategy has a great potential for detecting the expression methylation level of RNA in real sample. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Towards the development of a single-step immunosensor based on an electrochemical screen-printed electrode strip coupled with immunomagnetic beads.

    PubMed

    Volpe, G; Sozzo, U; Piermarini, S; Delibato, E; Palleschi, G; Moscone, D

    2013-01-01

    This work investigates the behaviour of two alternative systems that model the crucial event involved in any ELISA test, i.e. the molecular recognition between an antigen and its specific antibody on a solid phase, and its measurement. Each approach is devised with the goal of making possible a single-step, separation and wash-free amperometric magneto-immunosensor. Magnetic particles (MBs) are used as support for the immobilization of rabbit IgGs that are recognized by the specific anti-rabbit IgG-HRP. The assay protocol is based on the use of a series of small "reservoirs" containing phosphate buffer, hydroquinone, anti-rabbit IgG-HRP and an appropriate amount of MB-rabbit IgG. After a brief incubation, the content of each "reservoir" is transferred to one of the wells of a 8-well magnetized-screen-printed electrode strip. The resulting MB-IgG-anti-IgG-HRP chain, is then concentrated on the working electrode surface for electrochemical measurement. Two different approaches to monitor this immunological reaction are investigated. The first one is based on the enzyme-channeling principle (ECP) and involves the use of a second enzyme, glucose oxidase (GOD), immobilized on the working electrode previously modified with Prussian Blue. Since the H(2)O(2) produced by GOD is the co-substrate of the HRP enzyme, glucose is added into the well and the current, generated by the residual H(2)O(2), is measured. The second, more direct, approach is performed without exploiting ECP (no GOD enzyme), by adding H(2)O(2) into the well and measuring the current generated by the HRP product on a pristine screen-printed electrode. Both approaches yielded a typical sigmoidal binding curve, illustrating the discrimination between the signal produced by the immuno-bound HRP concentrated on the electrode surface, and the background signal due to HRP in the bulk solution.

  14. Fluorescent immunosensors using planar waveguides

    NASA Astrophysics Data System (ADS)

    Herron, James N.; Caldwell, Karin D.; Christensen, Douglas A.; Dyer, Shellee; Hlady, Vladimir; Huang, P.; Janatova, V.; Wang, Hiabo K.; Wei, A. P.

    1993-05-01

    The goal of our research program is to develop competitive and sandwich fluoroimmunoassays with high sensitivity and fast response time, that do not require external reagents. Our approach to this problem is to employ an optical immunoassay based on total internal reflection fluorescence (TIRF). Specifically, monoclonal antibodies are immobilized on a planar waveguide. Total internal reflection of light in the planar waveguide sets up an evanescent field which extends about 2000 angstroms from the interface. In the competitive immunoassay, a fluorescent label is coupled to a small synthetic antigen which is packaged with the antibody. In the absence of analyte, the fluorescently labeled antigen binds to the antibody and is excited by the evanescent field. Upon the addition of analyte, the fluorescently labeled antigen molecules are displaced by unlabeled antigen molecules and diffuse out of the evanescent field. In the sandwich assay, a primary or `capture' antibody is immobilized on the planar waveguide, and a secondary or `tracer' antibody (which is labeled with a fluorescent dye) is added to the bulk solution. In the absence of analyte, the tracer antibody remains in solution and very little fluorescence is observed. However, upon addition of analyte, a `molecular sandwich' is formed on the waveguide, composed of: (1) the capture antibody; (2) the analyte; and (3) the tracer antibody. Once this sandwich forms, the tracer antibody is within the evanescent field and fluoresces. Fluorescence emission is detected by a charged- coupled device (CCD). Using this approach, we have developed a prototype immunosensor for the detection of human chorionic gonadotropin (hCG). This device meets our design goals and exhibits a sensitivity of 0.1 - 1 pmolar.

  15. Comparison between a Direct-Flow SPR Immunosensor for Ampicillin and a Competitive Conventional Amperometric Device: Analytical Features and Possible Applications to Real Samples.

    PubMed

    Tomassetti, Mauro; Merola, Giovanni; Martini, Elisabetta; Campanella, Luigi; Sanzò, Gabriella; Favero, Gabriele; Mazzei, Franco

    2017-04-10

    In this research, we developed a direct-flow surface plasmon resonance (SPR) immunosensor for ampicillin to perform direct, simple, and fast measurements of this important antibiotic. In order to better evaluate the performance, it was compared with a conventional amperometric immunosensor, working with a competitive format with the aim of finding out experimental real advantages and disadvantages of two respective methods. Results showed that certain analytical features of the new SPR immunodevice, such as the lower limit of detection (LOD) value and the width of the linear range, are poorer than those of a conventional amperometric immunosensor, which adversely affects the application to samples such as natural waters. On the other hand, the SPR immunosensor was more selective to ampicillin, and measurements were more easily and quickly attained compared to those performed with the conventional competitive immunosensor.

  16. Conformation-sensitive antibody-based point-of-care immunosensor for serum Ca(2+) using two-dimensional sequential binding reactions.

    PubMed

    Park, Ji-Na; Paek, Sung-Ho; Kim, Dong-Hyung; Seo, Sung-Min; Lim, Guei-Sam; Kang, Ju-Hee; Paek, Sung-Pil; Cho, Il-Hoon; Paek, Se-Hwan

    2016-11-15

    To assess the homeostasis of Ca(2+) metabolism, we have developed a rapid immunosensor for ionic calcium using a membrane chromatographic technique. As calcium-binding protein (CBP) is available for the recognition and undergone conformation change upon Ca(2+) binding, a monoclonal antibody sensitive to the altered structure of CBP has been employed. The sequential binding scheme was mathematically simulated and shown to match with the experimental results. At the initial stage, the rapid analytical system using lateral flow was constructed by immobilizing the antibody on the immuno-strip nitrocellulose membrane and labeling CBP with colloidal gold as a tracer. A major problem with this system in measuring ionic calcium levels was retarded migration of the gold tracer along the immuno-strip. It was conceivable that the divalent cation at a high concentration caused a change in the physical properties of the tracer, resulting in a non-specific interaction with the membrane surface. This problem was circumvented by first eluting a sample containing biotinylated CBP along the immuno-strip and then supplying the gold coupled to streptavidin across the signal generation pad of the strip. The color signal was then generated via biotin-SA linkage and measured using a smartphone-based detector developed in our laboratory. This two-dimensional chromatographic format completed the Ca(2+) analysis within 15min, the analytical performance covered the clinical dynamic range (0.25-2.5mM) and highly correlated with that of the reference system, i-STAT. These results inspired us to eventually investigate a dual-immunoassay system that measures simultaneously ionic calcium and parathyroid hormone, which regulates the ionic calcium level in serum. This will significantly simplify the current diagnostic protocols, which involve separate devices. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. An ultrasensitive photoelectrochemical immunosensor for insulin detection based on BiOBr/Ag2S composite by in-situ growth method with high visible-light activity.

    PubMed

    Fan, Dawei; Wang, Haoyuan; Khan, Malik Saddam; Bao, Chunzhu; Wang, Huan; Wu, Dan; Wei, Qin; Du, Bin

    2017-11-15

    A novel ultrasensitive label-free immunosensor based on BiOBr/Ag2S composite with high visible-light photoelectrochemical activity was prepared for the detection of insulin. After BiOBr was modified by thioglycolic acid, Ag2S nanoparticles were grown in-situ on the surface of BiOBr hierarchical microspheres to first form novel BiOBr/Ag2S composite. When ascorbic acid (AA) was used as an efficient electron donor for scavenging photo-generated holes, BiOBr/Ag2S composite material showed excellent photoelectrochemical activity. In order to immobilize insulin antibody, adhesive polydopamine (PDA) film formed by self-polymerization of dopamine was fabricated onto BiOBr/Ag2S modified electrode. Moreover, PDA film could further enhance the visible light absorption of BiOBr/Ag2S. When the solutions of 0.08molL(-1)AgNO3 and 0.1molL(-1) AA were selected respectively during fabrication and detection process of this sensor, the best photocurrent singles were obtained. Under the optimum experimental condition, the specific binding between insulin and antibody resulted in a decrease in photocurrent intensity and the intensity decreased linearly with the logarithm of insulin concentration in the range of 0.001-20ngmL(-1) with a detection limit of 0.2pgmL(-1). The photoelectrochemical sensor ITO/BiOBr/Ag2S/PDA/anti-Insulin/BSA/Insulin revealed facile preparation, high sensitivity, and acceptable reproducibility, which may have practical applications in the biosensor, clinical diagnosis of cancers, photocatalysis, and other related fields. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. All-printed highly sensitive 2D MoS2 based multi-reagent immunosensor for smartphone based point-of-care diagnosis.

    PubMed

    Sajid, Memoon; Osman, Ahmed; Siddiqui, Ghayas Uddin; Kim, Hyun Bum; Kim, Soo Wan; Ko, Jeong Bum; Lim, Yoon Kyu; Choi, Kyung Hyun

    2017-07-19

    Immunosensors are used to detect the presence of certain bio-reagents mostly targeted at the diagnosis of a condition or a disease. Here, a general purpose electrical immunosensor has been fabricated for the quantitative detection of multiple bio-reagents through the formation of an antibody-antigen pair. The sensors were fabricated using all printing approaches. 2D transition metal dichalcogenide (TMDC) MoS2 thin film was deposited using Electrohydrodynamic atomization (EHDA) on top of an interdigitated transducer (IDT) electrode fabricated by reverse offset printing. The sensors were then treated with three different types of antibodies that were immobilized by physisorption into the highly porous multi-layered structure of MoS2 active layer. BSA was used as blocking agent to prevent non-specific absorption (NSA). The sensors were then employed for the targeted detection of the specific antigens including prostate specific antigen (PSA), mouse immunoglobulin-G (IgG), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). IgG was then selected to test the sensors for point of care (POC) diagnosis through a specially designed electronic readout system for sensors and interfacing it with a smartphone using Bluetooth connection. The sensors showed promising performance in terms of stability, specificity, repeatability, sensitivity, limit of detection (LoD), and range of detection (RoD).

  19. A double signal electrochemical human immunoglobulin G immunosensor based on gold nanoparticles-polydopamine functionalized reduced graphene oxide as a sensor platform and AgNPs/carbon nanocomposite as signal probe and catalytic substrate.

    PubMed

    Zhang, Si; Huang, Na; Lu, Qiujun; Liu, Meiling; Li, Haitao; Zhang, Youyu; Yao, Shouzhuo

    2016-03-15

    In this paper, a double signal electrochemical Human immunoglobulin G (HIgG) immunosensor based on AgNPs/carbon nanocomposite (Ag/C NC) as the signal probe and catalytic substrate was developed for fast and sensitive detection of HIgG. The as-prepared AuNPs-PDA-rGO nanocomposite and Ag/C NC were confirmed by UV-vis, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. Electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical properties of the proposed immunosensor. The AuNPs-PDA-rGO nanocomposite can improve the electron transfer rate and capture more Ab1. In the sandwich-type immunoassay process, the Ag/C NC functionalized bioconjugates were captured on HIgG/Ab1/AuNPs-PDA-rGO surface and the electrochemical double-signal strategy was employed. These double electrochemical detection signals were directly monitored the oxidation current originated from Ag/C NC and indirectly detected the reduction current of benzoquinone which was produced from the reaction of H2O2 and HQ by catalysis of Ag/C NC in electrochemical detection of HIgG. Under the optimized conditions, the current responses were changed with the concentrations of HIgG for the proposed immunosensor with wide linear ranges of 0.1 to 100 ngmL(-1) and 0.01-100 ngmL(-1) with the lowest detection concentration of 0.001 ng mL(-1) in the absence and presence of H2O2 and HQ. The double-signal strategy is used for detection of HIgG, and the results came from the two signals were well consistent with each other. The proposed immunosensor was successfully applied in analysis of human IgG in real samples and this strategy may provide a relative simple and effective method for construction of other immunsensors in detection of other biomarkers in clinical medicine. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Copper UPD as non-specific adsorption barrier in electrochemical displacement immunosensors.

    PubMed

    Duarte, M V; Lozano-Sanchez, P; Katakis, I

    2009-03-15

    Non-specific adsorption events are responsible to a large extent for the lack of reliability and applicability of electrochemical immunosensors. In the particular case of displacement-based immunosensors, as an approach to achieve reagentless, labelless and easy to use immunosensors, the hindering effect of then non-specific adsorption is amplified when the system presents a low affinity constant between biorecognition element and target. The application of Copper UPD as non-specific adsorption barrier in combination with the use of self-assembled monolayers (SAM) to provide efficient binding of biomolecules to the immunosensor electrode surface is shown to be a very promising mechanism to construct protein resistant surfaces with no harming effects on the electrochemical transducing mechanism. The electrochemical immunodetection of TCA (2,4,6-Trichloroanisole) has been chosen as example for a real case study. A monoclonal antibody to detect the target TCA and an appropriate sub-optimum antigen were used. In addition to a rational strategy for displacement immunosensor development, the decrease of non-specific adsorption phenomena by introducing Copper UPD is reported here. With such strategy an electrochemical displacement immunosensor with a limit of detection of 200ppb and response time of 10min is achieved.

  1. A new label-free electrochemical immunosensor based on dendritic core-shell AuPd@Au nanocrystals for highly sensitive detection of prostate specific antigen.

    PubMed

    Wang, Rui; Liu, Wei-Dong; Wang, Ai-Jun; Xue, Yadong; Wu, Liang; Feng, Jiu-Ju

    2018-01-15

    Herein, bimetallic dendritic core-shell AuPd@Au nanocrystals (AuPd@Au NCs) were prepared by a simple one-pot aqueous method using xanthine as a green growth-directing agent. By virtue of the enhanced peak currents in the H2O2 reduction catalyzed by AuPd@Au NCs, a label-free immunosensor was constructed for the detection of prostate specific antigen (PSA). The immunosensor exhibited significantly improved analytical performance for the assay of PSA with wide linear range of 0.1-50ngmL(-1) and low detection limit of 0.078ngmL(-1) (S/N = 3), coupled with the improved stability, reproducibility and selectivity. It provides a promising platform for clinical research and diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Molecular Architecture for Reagentless Immunosensors

    DTIC Science & Technology

    1990-11-01

    summarized in the final report. 14. SUBJECT TERMS 15. NUMBER OF PAGES ’:Immunoglobu~ins, Innunosensors, Immunoassays, Proteins, 6 Biosensors 16. PRICE CODE 17...MONITORING OF ANALYTE CONCENTRATIONS. W. Schramm and S-H. Paek. First World Congress on Biosensors , Singapore. May 1990. Biosensors Bioelectron...W. Schramm and S-H. Paek. Submitted 1990. ENZYME-ANALYTE CONJUGATES AS SIGNAL GENERATORS FOR AMPEROMETRIC IMMUNOSENSORS: IMMUNOCHEMICAL PHENOMENA

  3. Electrochemical immunosensor for the milk allergen β-lactoglobulin based on electrografting of organic film on graphene modified screen-printed carbon electrodes.

    PubMed

    Eissa, Shimaa; Tlili, Chaker; L'Hocine, Lamia; Zourob, Mohammed

    2012-01-01

    A novel label-free voltammetric immunosensor for sensitive detection of β-lactoglobulin using graphene modified screen printed electrodes has been developed. The derivatization of the graphene electrode surface was achieved by electrochemical reduction of in situ generated 4-nitrophenyl diazonium cations in aqueous acidic solution, followed by electrochemical reduction of the terminal nitro groups to amines. The electrochemical modification protocol was optimized in order to generate monolayer of nitrophenyl groups on the graphene surface without complete passivation of the electrode. Unlike the reported method for graphene functionalization, we demonstrated here the ability of the electrografting of aryl diazonium salt to attach an organic film to the graphene surface in a controlled manner by choosing the suitable grafting protocol. Next, the amine groups on the graphene surface were activated using glutaraldehyde and used for the covalent immobilization of β-lactoglobulin antibodies. Cyclic and differential pulse voltammetry carried out in an aqueous solution containing [Fe(CN)(6)](3-/4-) redox pair have been used for the immunosensor characterization. The results demonstrated that the DPV reduction peak current of [Fe(CN)(6)](3-/4-) decreased linearly with increasing the concentration of β-lactoglobulin due to the formation of antibody-antigen complex on the modified electrode surface. The immunosensor obtained using this novel approach enabled a detection limit of 0.85 pg mL(-1) and a dynamic range from 1 pg mL(-1) to 100 ng mL(-1) of β-lactoglobulin in PBS buffer. In addition, the immunosensor evaluated in different samples including cake, cheese snacks, a sweet biscuit, showing excellent correlation with the results obtained from commercially enzyme-linked immunosorbent assay (ELISA) method. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Electrochemical impedance immunosensor for sub-picogram level detection of bovine interferon gamma based on cylinder-shaped TiO₂ nanorods.

    PubMed

    Yang, Zhanjun; Jian, Zhiqin; Chen, Xiang; Li, Juan; Qin, Piya; Zhao, Jie; Jiao, Xin'an; Hu, Xiaoya

    2015-01-15

    Bovine interferon gamma (BoIFN-γ) released by T cells plays very important roles in early diagnosis of Mycobacterium tuberculosis (MTB) infections and control of bovine tuberculosis. In this work, a label-free electrochemical impedance immunosensor is for the first time developed for highly sensitive determination of BoIFN-γ. Cylinder-shaped TiO2 nanorods are synthesized by a facile hydrothermal method, and show high surface area and good hydrophicility. The immunosensor is fabricated by the immobilization of BoIFN-γ monoclonal antibody on the TiO2 nanorods modified glassy carbon electrode. The prepared TiO2 and immunosensor are characterized using transmission electron microscopy, scanning electron microscopy, X-ray diffraction, contact angle measurement, cyclic voltammetry, and electrochemical impedance spectra. The BoIFN-γ concentration is measured through the relative increase of impedance values in corresponding specific binding of BoIFN-γ antigen and BoIFN-γ antibody. The relative increased impedance values are proportional to the logarithmic value of BoIFN-γ concentrations in a wide range of 0.0001 to 0.1 ng/mL with a low detection limit of 0.1 pg/mL. The developed BoIFN-γ immunosensor shows a 249-fold decrease in detection limit in comparison with current enzyme-linked immunosorbent assay. This study provides a new, simple, and highly sensitive approach for very potential application in early diagnosis of MTB infections and control of bovine tuberculosis.

  5. An ultrasensitive sandwich-type electrochemical immunosensor based on the signal amplification strategy of mesoporous core-shell Pd@Pt nanoparticles/amino group functionalized graphene nanocomposite.

    PubMed

    Li, Mingdang; Wang, Ping; Li, Faying; Chu, Qingyan; Li, Yueyun; Dong, Yunhui

    2017-01-15

    Herein, a novel and sensitive sandwich-type electrochemical immunosensor was fabricated for quantitative monitoring of prostate specific antigen (PSA). The sulfo group functionalized multi-walled carbon nanotubes (MWCNTs-SO3H) were used as substrate material to increase the specific surface area and enhance the conductivity of the glassy carbon electrode. Gold nanoparticles (Au NPs) were introduced to enhance the load capacity of the substrate material for primary antibodies (Ab1) and accelerate the electron transfer on the electrode interface. The mesoporous core-shell Pd@Pt nanoparticle loaded by amino group functionalized graphene (M-Pd@Pt/NH2-GS) with high specific surface area, high indexed facets, and good biocompatibility was not only as the carriers of secondary antibodies (Ab2) but also catalyzed the reduction of hydrogen peroxide (H2O2), which effectually amplified the current signal in detection of PSA. The as-proposed immunosensor exhibited high sensitivity and stability on the detection of PSA. A linear relationship between current signals and the concentrations of PSA was obtained in the range from 10fg/mL to 50ng/mL and the detection limit of PSA was 3.3fg/mL (signal-to-noise ratio of 3). Furthermore, the as-proposed immunosensor showed excellent performance in detection of human serum samples. The results suggest that the proposed immunosensor will be promising in the diagnostics application for accurately quantitative detection of PSA. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. An electrochemiluminescence immunosensor for thyroid stimulating hormone based on polyamidoamine-norfloxacin functionalized Pd-Au core-shell hexoctahedrons as signal enhancers.

    PubMed

    Liu, Yuting; Zhang, Qiqi; Wang, Haijun; Yuan, Yali; Chai, Yaqin; Yuan, Ruo

    2015-09-15

    In this work, a novel polyamidoamine-norfloxacin (PAMAM-NFLX) complex and core-shell Pd-Au hexoctahedrons (Pd@Au HOHs) as enhancers are employed for development of a sensitive sandwich-type electrochemiluminescence (ECL) immunosensor to detect thyroid stimulating hormone (TSH). Here, norfloxacin (NFLX) is decorated abundantly on the surface of polyamidoamine (PAMAM) dendrimer via amide linkage to form PAMAM-NFLX complex. Thus, the resultant PAMAM-NFLX can serve as a novel co-reactant to efficiently amplify the ECL signal of peroxydisulfate-oxygen (S2O8(2-)-O2) system. Pd@Au HOHs were used as nano-carriers to assemble detection antibody (Ab2) and the PAMAM-NFLX complex. Besides, it can further enhance the ECL signal by promoting the generation of intermediate free radical HO(•) during the ECL reaction of S2O8(2-)-O2 system. The proposed immunosensor shows high sensitivity and specificity, and responds linearly to the concentration of TSH from 0.05 to 20 μIU mL(-1) with a low detection limit of 0.02 μIU mL(-1) (S/N=3). Moreover, the immunosensor successfully achieves the detection of TSH in practical human blood serum with desirable results. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Sensitive Electrochemical Immunosensor for Detection of Nuclear Matrix Protein-22 based on NH2-SAPO-34 Supported Pd/Co Nanoparticles

    PubMed Central

    Wu, Dan; Wang, Yaoguang; Zhang, Yong; Ma, Hongmin; Yan, Tao; Du, Bin; Wei, Qin

    2016-01-01

    A novel sandwich-type electrochemical immunosensor using the new amino group functionalized silicoaluminophosphates molecular sieves (NH2-SAPO-34) supported Pd/Co nanoparticles (NH2-SAPO-34-Pd/Co NPs) as labels for the detection of bladder cancer biomarker nuclear matrix protein-22 (NMP-22) was developed in this work. The reduced graphene oxide-NH (rGO-NH) with good conductivity and large surface area was used to immobilize primary antibody (Ab1). Due to the excellent catalytic activity toward hydrogen peroxide, NH2-SAPO-34-Pd/Co NPs were used as labels and immobilized secondary antibody (Ab2) through adsorption capacity of Pd/Co NPs to protein. The immunosensor displayed a wide linear range (0.001–20 ng/mL) and low detection limit (0.33 pg/mL). Good reproducibility and stability have showed satisfying results in the analysis of clinical urine samples. This novel and ultrasensitive immunosensor may have the potential application in the detection of different tumor markers. PMID:27086763

  8. Electrochemical aptamer/antibody based sandwich immunosensor for the detection of EGFR, a cancer biomarker, using gold nanoparticles as a signaling probe.

    PubMed

    Ilkhani, Hoda; Sarparast, Morteza; Noori, Abolhassan; Zahra Bathaie, S; Mousavi, Mir F

    2015-12-15

    Detection of epidermal growth factor receptor (EGFR) in biological fluids is of paramount importance, since it has significant application in cancer diagnosis, drug development, and therapy monitoring. EGFR is a cancer biomarker, and its overexpression is associated with the development of some types of cancer. Herein, we report on the development of a sensitive and selective electrochemical aptamer/antibody (Apt/Ab) sandwich immunosensor for detection of EGFR. In this study, a biotinylated anti-human EGFR Apt was immobilized on streptavidin-coated magnetic beads (MB) and served as a capture probe. A polyclonal anti-human EGFR Ab was conjugated to citrate-coated gold nanoparticles (AuNPs) and used as a signaling probe. In the presence of EGFR, an Apt-EGFR-Ab sandwich was formed on the MB surface. The extent of the complexation was evaluated by differential pulse voltammetry of AuNPs after their dissolution in HCl. Under optimal conditions, the dynamic concentration range of the immunosensor for EGFR spanned from 1 to 40 ng/mL, with a low detection limit of 50 pg/mL, and RSD percent of less than 4.2%. The proposed approach takes advantage of sandwich assay for high specificity, MBs for fast separation, and electrochemical method for cost-effective and sensitive detection. In this proof-of-principle study, we demonstrate the potential clinical efficacy of the immunosensor for monitoring of chemotherapy effectiveness in breast cancer samples.

  9. A disposable amperometric immunosensor for chlorpyrifos-methyl based on immunogen/platinum doped silica sol-gel film modified screen-printed carbon electrode.

    PubMed

    Wei, Wei; Zong, Xiaomin; Wang, Xuan; Yin, Lihong; Pu, Yuepu; Liu, Songqin

    2012-12-01

    A disposable amperometric immunosensor for sensitive detection of chlorpyrifos-methyl (CM) has been developed by combining dual signal amplification of platinum colloid with an enzymatic catalytic reaction. The immunosensor was fabricated by modification of the screen-printed carbon electrodes (SPCE) with nanocomposites made by skillful doping of bovine serum albumin conjugated chlorpyrifos-methyl antigen (BSA-Ag) and platinum colloid into silica sol-gel. The scanning electron microscope (SEM) images and electrochemical measurements showed that platinum colloid domains in the nanocomposite material could enhance electron transfer and change the brittleness of the silica sol-gel. The immobilisation of BSA-Ag on the nanocomposite retained its immunoactivities, which allowed the immobilised BSA-Ag to effectively capture unbound Ab-HRP in the detection solution. A linear response to CM concentration was exhibited, ranging from 0.4 to 20ng/mL. Detection of CM with the presented method in soil or grape samples treated with CM matched the reference values well, which indicated that the proposed disposable immunosensor hold promising applications in environmental and food monitoring.

  10. Ru(bpy)32+/nanoporous silver-based electrochemiluminescence immunosensor for alpha fetoprotein enhanced by gold nanoparticles decorated black carbon intercalated reduced graphene oxide

    PubMed Central

    Zhu, Wenjuan; Lv, Xiaohui; Wang, Qi; Ma, Hongmin; Wu, Dan; Yan, Tao; Hu, Lihua; Du, Bin; Wei, Qin

    2016-01-01

    A highly sensitive sandwich-type electrochemiluminescence (ECL) immunosensor was proposed for the quantitative determination of alpha fetoprotein (AFP) using gold nanoparticles decorated black carbon intercalated reduced graphene oxide (Au-rGO@CB) as sensing platform and nanoporous silver (NPS) loaded Ru(bpy)32+ as labels. In this work, intercalation of CB inhibited the accumulation of rGO and Au-rGO@CB was firstly used to immobilize primary antibody (Ab1) in ECL system. NPS prepared by the dealloying of binary alloy has high pore volume and surface areas, which was used to load amount of secondary antibodies (Ab2) and Ru(bpy)32+, which could greatly enhance the ECL intensity. Under optimal conditions, the designed immunosensor exhibited wider linear range from 0.0001 to 30 ng/mL with a relative lower detection limit of 33 fg/mL for AFP detection. Overall, the designed immunosensor exhibited high sensitivity and selectivity, good repeatability and stability. This proposed method provided a potential application for clinical monitoring of AFP. PMID:26829062

  11. Highly sensitive electrochemical immunosensor for the detection of alpha fetoprotein based on PdNi nanoparticles and N-doped graphene nanoribbons.

    PubMed

    Li, Na; Ma, Hongmin; Cao, Wei; Wu, Dan; Yan, Tao; Du, Bin; Wei, Qin

    2015-12-15

    An ultrasensitive sandwich-type electrochemical immunosensor was designed for the quantitative detection of alpha fetoprotein (AFP). The β-cyclodextrins functionalized graphene sheets (CD-GS) were used as the sensing matrix for immobilizing adamantine-1-carboxylic acid functionalized primary anti-AFP (ADA-Ab1) and enhanced the electron transfer. PdNi alloy nanoparticles decorated N-doped graphene nanoribbons (PdNi/N-GNRs) were used as labels of secondary anti-AFP (Ab2), and PdNi alloy nanoparticles (PdNi NPs) exhibited high catalytic performance towards the reduction of H2O2. Meanwhile, with good dispersion, large specific surface area and good catalytic performance, N-doped graphene nanoribbons (N-GNRs) significantly amplified the electrochemical signal. Under the optimal conditions, the electrochemical immunosensor exhibited a wide linear range of 0.0001-16 ng/mL with a low detection limit of 0.03 pg/mL. Additionally, the proposed immunosensor showed high specificity, good reproducibility and long-term stability, which have promising application in bioassay analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Electrochemical immunosensor for detecting typical bladder cancer biomarker based on reduced graphene oxide-tetraethylene pentamine and trimetallic AuPdPt nanoparticles.

    PubMed

    Ma, Hongmin; Zhang, Xiaoyue; Li, Xiaojian; Li, Rongxia; Du, Bin; Wei, Qin

    2015-10-01

    A highly sensitive electrochemical immunosensor for detection of typical bladder cancer biomarker-nuclear matrix protein 22 (NMP22) was developed by using reduced graphene oxide-tetraethylene pentamine (rGO-TEPA) and trimetallic AuPdPt nanoparticles (NPs). rGO-TEPA was used as the ideal material for signal amplification and AuPdPt NPs immobilization due to its excellent conductivity and large surface area. An effective platform was constructed for antibodies anchoring by using AuPdPt NPs, which kept the antibodies' high stability and bioactivity. Moreover, AuPdPt NPs could accelerate the electron transfer and enhance the signal response, which assisted by the synergistic effect of the three different metals (Au, Pd and Pt). The proposed immunosensor showed satisfied performance such as simple fabrication, low detection limits (0.01 U/mL), wide linear range (from 0.040 to 20 U/mL), short analysis time (2 min), high stability and selectivity in the detection of NMP22. Furthermore, the proposed immunosensor was employed to test real urine samples with satisfactory results.

  13. An Electrochemical Immunosensor for Detection of Staphylococcus aureus Bacteria Based on Immobilization of Antibodies on Self-Assembled Monolayers-Functionalized Gold Electrode

    PubMed Central

    Braiek, Mohamed; Rokbani, Karima Bekir; Chrouda, Amani; Mrabet, Béchir; Bakhrouf, Amina; Maaref, Abderrazak; Jaffrezic-Renault, Nicole

    2012-01-01

    The detection of pathogenic bacteria remains a challenge for the struggle against biological weapons, nosocomial diseases, and for food safety. In this research, our aim was to develop an easy-to-use electrochemical immunosensor for the detection of pathogenic Staphylococcus aureus ATCC25923. The biosensor was elaborated by the immobilization of anti-S. aureus antibodies using a self-assembled monolayer (SAMs) of 3-Mercaptopropionic acid (MPA). These molecular assemblies were spontaneously formed by the immersion of the substrate in an organic solvent containing the SAMs that can covalently bond to the gold surface. The functionalization of the immunosensor was characterized using two electrochemical techniques: cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Here, the analysis was performed in phosphate buffer with ferro/ferricyanide as the redox probe. The EIS technique was used for affinity assays: antibody-cell binding. A linear relationship between the increment in the electron transfer resistance (RCT) and the logarithmic value of S. aureus concentration was observed between 10 and 106 CFU/mL. The limit of detection (LOD) was observed at 10 CFU/mL, and the reproducibility was calculated to 8%. Finally, a good selectivity versus E. coli and S. epidermidis was obtained for our developed immunosensor demonstrating its specificity towards only S. aureus. PMID:25586032

  14. Ultrasensitive electrochemical immunosensor for alpha fetoprotein detection based on platinum nanoparticles anchored on cobalt oxide/graphene nanosheets for signal amplification.

    PubMed

    Liu, Li; Tian, Lihui; Zhao, Guanhui; Huang, Yuzhen; Wei, Qin; Cao, Wei

    2017-09-15

    An ultrasensitive sandwich-type electrochemical immunosensor was developed for quantitative monitoring of Alpha fetoprotein (AFP). To achieve this objective, an incorporated signal amplification strategy of platinum nanoparticles anchored on cobalt oxide/graphene nanosheets (Pt NPs/Co3O4/graphene) was proposed by acting as the label of secondary antibodies. The prepared label not only empowered by advantages of each component but exhibited better electrochemical performance than single Pt NPs, Co3O4 and graphene, which has shown large specific surface area and good catalytic activity towards the reduction of H2O2. Meanwhile, the nanocomposite of gold nanoparticles adhered on 3-mercaptopropyltriethoxysilane functionalized graphene sheets (Au@MPTES-GS) was used as matrix to accelerate electron transfer and immobilize primary antibodies in this system. The signal amplification mechanism of the matrix and the label were explored successfully. Under optimal conditions, the electrochemical immunosensor exhibited a wide linear range from 0.1 pg mL(-1) to 60 ng mL(-1) with a low detection limit of 0.029 pg mL(-1)for AFP. The proposed immunosensor may have promising application in the clinical diagnosis of AFP and other tumor markers. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Sensitive Electrochemical Immunosensor for Detection of Nuclear Matrix Protein-22 based on NH2-SAPO-34 Supported Pd/Co Nanoparticles.

    PubMed

    Wu, Dan; Wang, Yaoguang; Zhang, Yong; Ma, Hongmin; Yan, Tao; Du, Bin; Wei, Qin

    2016-04-18

    A novel sandwich-type electrochemical immunosensor using the new amino group functionalized silicoaluminophosphates molecular sieves (NH2-SAPO-34) supported Pd/Co nanoparticles (NH2-SAPO-34-Pd/Co NPs) as labels for the detection of bladder cancer biomarker nuclear matrix protein-22 (NMP-22) was developed in this work. The reduced graphene oxide-NH (rGO-NH) with good conductivity and large surface area was used to immobilize primary antibody (Ab1). Due to the excellent catalytic activity toward hydrogen peroxide, NH2-SAPO-34-Pd/Co NPs were used as labels and immobilized secondary antibody (Ab2) through adsorption capacity of Pd/Co NPs to protein. The immunosensor displayed a wide linear range (0.001-20 ng/mL) and low detection limit (0.33 pg/mL). Good reproducibility and stability have showed satisfying results in the analysis of clinical urine samples. This novel and ultrasensitive immunosensor may have the potential application in the detection of different tumor markers.

  16. A label-free immunosensor array using single-chain antibody fragments.

    PubMed

    Backmann, Natalija; Zahnd, Christian; Huber, Francois; Bietsch, Alexander; Plückthun, Andreas; Lang, Hans-Peter; Güntherodt, Hans-Joachim; Hegner, Martin; Gerber, Christoph

    2005-10-11

    We report a microcantilever-based immunosensor operated in static deflection mode with a performance comparable with surface plasmon resonance, using single-chain Fv (scFv) antibody fragments as receptor molecules. As a model system scFv fragments with specificity to two different antigens were applied. We introduced a cysteine residue at the C terminus of each scFv construct to allow covalent attachment to gold-coated sensor interfaces in directed orientation. Application of an array enabled simultaneous deflection measurements of sensing and reference cantilevers. The differential deflection signal revealed specific antigen binding and was proportional to the antigen concentration in solution. Using small, oriented scFv fragments as receptor molecules we increased the sensitivity of microcantilevers to approximately 1 nM.

  17. A label-free immunosensor array using single-chain antibody fragments

    PubMed Central

    Backmann, Natalija; Zahnd, Christian; Huber, Francois; Bietsch, Alexander; Plückthun, Andreas; Lang, Hans-Peter; Güntherodt, Hans-Joachim; Hegner, Martin; Gerber, Christoph

    2005-01-01

    We report a microcantilever-based immunosensor operated in static deflection mode with a performance comparable with surface plasmon resonance, using single-chain Fv (scFv) antibody fragments as receptor molecules. As a model system scFv fragments with specificity to two different antigens were applied. We introduced a cysteine residue at the C terminus of each scFv construct to allow covalent attachment to gold-coated sensor interfaces in directed orientation. Application of an array enabled simultaneous deflection measurements of sensing and reference cantilevers. The differential deflection signal revealed specific antigen binding and was proportional to the antigen concentration in solution. Using small, oriented scFv fragments as receptor molecules we increased the sensitivity of microcantilevers to ≈1 nM. PMID:16192357

  18. A sensitive electrochemiluminescence immunosensor based on Ru(bpy)3(2+) in 3D CuNi oxalate as luminophores and graphene oxide-polyethylenimine as released Ru(bpy)3(2+) initiator.

    PubMed

    Li, Xiaojian; Yu, Siqi; Yan, Tao; Zhang, Yong; Du, Bin; Wu, Dan; Wei, Qin

    2017-03-15

    In this work, electrochemiluminescence (ECL) luminophor Ru(bpy)3(2+) was encapsulated in 3D CuNi oxalate and the synthesized metal-inorganic frameworks {[Ru(bpy)3][Cu2xNi2(1-x)(ox)3]}n (Ru/Cu/Ni) exhibited excellent and stable ECL signals, which could be decreased by polyethylenimine capped graphene oxide (GO-PEI). Based on this, a new sandwich ECL immunosensor was developed for detection of carcinoembryonic antigen (CEA). To capture primary antibody and second antibody more simply and efficiently, Ag nanoparticles were doped with Ru/Cu/Ni and GO-PEI. After a sandwich-type immunoreaction, a remarkable decrease of ECL signal was observed due to the release of Ru(bpy)3(2+) which was caused by the coordination between PEI and metal ions. Under the optimization of determination conditions, a linear response range for CEA from 0.1pgmL(-1) to 100ngmL(-1) was obtained, and the detection limit was calculated to be 0.027pgmL(-1) (S/N=3). The prepared CEA immunosensor displayed high sensitivity, excellent stability and good specificity.

  19. New competitive dendrimer-based and highly selective immunosensor for determination of atrazine in environmental, feed and food samples: the importance of antibody selectivity for discrimination among related triazinic metabolites.

    PubMed

    Giannetto, Marco; Umiltà, Eleonora; Careri, Maria

    2014-01-02

    A new voltammetric competitive immunosensor selective for atrazine, based on the immobilization of a conjugate atrazine-bovine serum albumine on a nanostructured gold substrate previously functionalized with poliamidoaminic dendrimers, was realized, characterized, and validated in different real samples of environmental and food concern. Response of the sensor was reliable, highly selective and suitable for the detection and quantification of atrazine at trace levels in complex matrices such as territorial waters, corn-cultivated soils, corn-containing poultry and bovine feeds and corn flakes for human use. Selectivity studies were focused on desethylatrazine, the principal metabolite generated by long-term microbiological degradation of atrazine, terbutylazine-2-hydroxy and simazine as potential interferents. The response of the developed immunosensor for atrazine was explored over the 10(-2)-10(3) ng mL(-1) range. Good sensitivity was proved, as limit of detection and limit of quantitation of 1.2 and 5 ng mL(-1), respectively, were estimated for atrazine. RSD values <5% over the entire explored range attested a good precision of the device.

  20. Droplet resonator based optofluidic microlasers

    NASA Astrophysics Data System (ADS)

    Kiraz, Alper; Jonáš, Alexandr; Aas, Mehdi; Karadag, Yasin; Brzobohatý, Oto; Ježek, Jan; Pilát, Zdeněk.; Zemánek, Pavel; Anand, Suman; McGloin, David

    2014-03-01

    We introduce tunable optofluidic microlasers based on active optical resonant cavities formed by optically stretched, dye-doped emulsion droplets confined in a dual-beam optical trap. To achieve tunable dye lasing, optically pumped droplets of oil dispersed in water are stretched by light in the dual-beam trap. Subsequently, resonant path lengths of whispering gallery modes (WGMs) propagating in the droplet are modified, leading to shifts in the microlaser emission wavelengths. We also report lasing in airborne, Rhodamine B-doped glycerolwater droplets which were localized using optical tweezers. While being trapped near the focal point of an infrared laser, the droplets were pumped with a Q-switched green laser. Furthermore, biological lasing in droplets supported by a superhydrophobic surface is demonstrated using a solution of Venus variant of the yellow fluorescent protein or E. Coli bacterial cells expressing stably the Venus protein. Our results may lead to new ways of probing airborne particles, exploiting the high sensitivity of stimulated emission to small perturbations in the droplet laser cavity and the gain medium.

  1. Immunosensor Incorporating Anti-His (C-term) IgG F(ab’) Fragments Attached to Gold Nanorods for Detection of His-Tagged Proteins in Culture Medium

    PubMed Central

    Wąsowicz, Michal; Milner, Małgorzata; Radecka, Dorota; Grzelak, Krystyna; Radecka, Hanna

    2010-01-01

    Immunosensors based on gold electrodes (electrochemical) or gold discs (optical) modified with 1,6-hexanedithiol, gold nanorods and Anti-His (C-term) monoclonal antibody F(ab’) fragment are described. The antigen detected by the sensing platform is a recombinant histidine-tagged silk proteinase inhibitor (rSPI2-His6). Electrochemical impedance spectroscopy (EIS) and surface plasmon resonance (SPR) techniques were used as methods for detection of the antigen. This approach allows to detect the antigen protein in concentration of 10 pg per mL (0.13 pM) of culture medium. The immunosensor shows good reproducibility due to covalent immobilization of F(ab’) fragments to gold nanorods layer. PMID:22219669

  2. Micro amperometric immunosensor for the detection of salmonella typhimurium

    NASA Astrophysics Data System (ADS)

    Sun, Jizhou; Xia, Shanhong; Bian, Chao; Qu, Lan

    2008-12-01

    In this paper, a micro amperometric immunosensor based on Micro-Electro-Mechanical Systems technology for the detection of Salmonella typhimurium (S. typhimurium) was constructed by immobilizing a polyclonal antibody (the bio-molecular recognition element) onto the surface of polypyrrole(PPy) /staphylococcal protein A(SPA) modified Pt electrode. Pyrrole doped with SPA was co-electropolymerized onto the working electrode surface by cyclic voltammetry in 10 minutes for orientation-controlled immobilization of salmonella capture antibodies. S. typhimurium with the concentration of 102cfu/ml could be detected by this immunosensor with a controllable and convenient manipulation to effectively modify the sensing surface more rapidly with less consumption of reagent (10µL), which showed the good property of the sensor. It is potential to develop a micro biosensor that can be used for convenient, accurate, cost-effective and real-time sensing of pathogens in food products.

  3. A piezoelectric immunosensor for Leishmania chagasi antibodies in canine serum.

    PubMed

    Ramos-Jesus, Joilson; Carvalho, Kellyanne A; Fonseca, Rosana A S; Oliveira, Geraldo G S; Melo, Stella M Barrouin; Alcântara-Neves, Neuza M; Dutra, Rosa F

    2011-08-01

    The American visceral leishmaniasis is an important cause of morbidity and mortality in Brazil for both humans and dogs. Attempts to make a diagnosis of this disease need to be improved, especially in endemic areas, and in the tracking and screening of asymptomatic dogs, which are their main host in urban areas. A quartz crystal microbalance immunosensor for the diagnosis of the canine visceral leishmaniasis using a recombinant antigen of Leishmania chagasi (rLci2B-NH6) was developed. The rLci2B-NH6 was tightly immobilized on a quartz crystal gold electrode by self-assembled monolayer based on short-chain length thiol. The strategy was the use of the antigen-histidine tail covalently linked to glutaraldehyde performing a Schift base which permits a major exposure of epitopes and a reduced steric hindrance. The immunosensor showed good results regarding sensitivity and reproducibility, being able to distinguish positive and negative canine serum for L. chagasi. Furthermore, the immunosensor can be reused through exposure to sodium dodecyl sulfate solution, which promotes the dissociation of antigen-antibody binding, restoring the sensor surface with immobilized biologically active antigens for further analysis.

  4. Emats for Immunosensors

    NASA Astrophysics Data System (ADS)

    Ogi, H.; Motohisa, K.; Hoso, Y.; Hatanaka, K.; Ohmori, T.; Hirao, H.

    2008-02-01

    Electromagnetic acoustic transducers (EMATs) have two inherent advantages. First, they allow the wireless-electrodeless measurements. Second, they show higher efficiency for exciting and detecting bulk shear waves. These two characteristics are essential for achieving a high-sensitive oscillator biosensor. This paper shows a Lorentz-force-EMAT biosensor with 50-μm thick aluminum foil for detecting human immunoglobulin G (IgG) by Staphylococcus-aureus protein A immobilized on both surfaces of the foil oscillator. The fundamental resonance frequency near 32 MHz was monitored during the binding reaction, which successfully detected the frequency change for the IgG solution with a concentration of 1 ng/mL.

  5. Liquid crystal and gold nanoparticles applied to electrochemical immunosensor for cardiac biomarker.

    PubMed

    Zapp, Eduardo; Westphal, Eduard; Gallardo, Hugo; de Souza, Bernardo; Cruz Vieira, Iolanda

    2014-09-15

    A label-free electrochemical immunosensor based on the ionic liquid crystal (E)-1-decyl-4-[(4-decyloxyphenyl)diazenyl]pyridinium bromide (Br-Py) coated on a glassy carbon electrode (GCE) for the quantitative detection of myoglobin (Mb), a cardiac marker for acute myocardial infarction, is reported herein for the first time. The monoclonal anti-myoglobin antibody (ab-Mb) was covalently immobilized using glyoxal on a film of polyethyleneimine-coated gold nanoparticles (AuNP-PEI). The proposed method for Mb detection is based on voltammetric suppression of the Br-Py signal when the immunosensor was incubated with Mb antigen. The electrochemical performance of the Mb immunosensor was studied by electrochemical impedance spectroscopy, and cyclic and square-wave voltammetry. Under the optimal conditions, the proposed immunosensor shows a good linear relationship between the electrochemical inhibition response and the concentration of Mb over the range of 9.96-72.8 ng mL(-1) with a detection limit of 6.29 ng mL(-1). The results obtained indicate that the proposed immunosensor provides good sensitivity and simple operation for detecting acute myocardial infarction with Mb as a biomarker. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Label-free immunosensor based on one-step electrodeposition of chitosan-gold nanoparticles biocompatible film on Au microelectrode for determination of aflatoxin B1 in maize.

    PubMed

    Ma, Haihua; Sun, Jizhou; Zhang, Yuan; Bian, Chao; Xia, Shanhong; Zhen, Tong

    2016-06-15

    Gold nanoparticles (AuNPs) embedded in chitosan (CHI) film, well-dispersed and smaller in size (about 10 nm), were fabricated by one-step electrodeposion on Au microelectrode in solution containing chitosan and chloride trihydrate. The nano-structure CHI-AuNPs composite film offers abundant amine groups, good conductivity, excellent biocompatibility and stability for antibody immobilization. The combination of aflatoxin B1 (AFB1) with immobilized antibody introduces a barrier to electron transfer, resulting in current decreasement. The morphologies and characterizations of modified microelectrodes were investigated by scanning electron microscope (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FT-IR). The proposed non-enzyme and label-free immunosensor exhibited high sensitive amperometric response to AFB1 concentration in two linear ranges of 0.1 to 1 ng mL(-1) and 1 to 30 ng mL(-1), with the detection limit of 0.06 ng mL(-1) (S/N=3). The immunoassay was also applied for analysis of maize samples spiked with AFB1. Considering the sample extraction procedure, the linear range and limit of detection were assessed to be 1.6-16 ng mL(-1) and 0.19 ng mL(-1) respectively. The simple method showed good fabrication controllability and reproducibility for immunosensor design. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Rapid quantitative detection of Brucella melitensis by a label-free impedance immunosensor based on a gold nanoparticle-modified screen-printed carbon electrode.

    PubMed

    Wu, Haiyun; Zuo, Yueming; Cui, Chuanjin; Yang, Wei; Ma, Haili; Wang, Xiaowen

    2013-07-04

    A rapid and simple method for quantitative monitoring of Brucella melitensis using electrochemical impedance spectroscopy (EIS) is reported for the first time. The label-free immunosensors were fabricated by immobilizing Brucella melitensis antibody on the surface of gold nanoparticle-modified screen-printed carbon electrodes (GNP-SPCEs). Cyclic voltammetry (CV) and EIS were used to characterize the Brucella melitensis antigen interaction on the surface of GNP-SPCEs with antibody. A general electronic equivalent model of an electrochemical cell was introduced for interpretation of the impedance components of the system. The results showed that the change in electron-transfer resistance (Rct) was significantly different due to the binding of Brucella melitensis cells. A linear relationship between the Rct variation and logarithmic value of the cell concentration was found from 4 × 10(4) to 4 × 10(6) CFU/mL in pure culture. The label-free impedance biosensor was able to detect as low as 1 × 10(4) and 4 × 10(5) CFU/mL of Brucella melitensis in pure culture and milk samples, respectively, in less than 1.5 h. Moreover, a good selectivity versus Escherichia coli O157:H7 and Staphylococcus aureus cells was obtained for our developed immunosensor demonstrating its specificity towards only Brucella melitensis.

  8. Coupled solid phase extraction and microparticle-based stability and purity-indicating immunosensor for the determination of recombinant human myelin basic protein in transgenic milk.

    PubMed

    Al-Ghobashy, Medhat A; Williams, Martin A K; Laible, Götz; Harding, David R K

    2013-05-15

    An optical immunosensor was developed and validated on the surface of microparticles for the determination of a biopharmaceutical protein. The recombinant human myelin basic protein (rhMBP) was produced in milk of transgenic cows as a His-tagged fusion protein. Previous work indicated exclusive association of rhMBP with milk casein micelles that hindered direct determination of the protein in milk. In this work, a solid phase extraction using a cation exchange matrix was developed in order to liberate rhMBP from casein micelles. A sandwich-type immunoassay was then used for in-process monitoring of the full-length protein in the presence of major milk proteins. The assay was successfully employed for detection of ultra-traces of rhMBP (LOD=6.04 ng mL(-1)≈0.3 n mol L(-1)) and for quantitative determination over a wide concentration range (10.00-10,000.00 ng mL(-1)). The assay was able also to detect the rhMBP in the presence of its human counterpart that lacks the His-tag. The high sensitivity along with the ability of the assay to determine the full length protein enabled monitoring of the stability of rhMBP. The testing protocol is particularly useful for intrinsically unstructured proteins that are extremely sensitive to proteolysis and lack a traceable enzymatic activity. This immunosensor provides a specific, ultrasensitive high throughput tool for in-process monitoring in biopharmaceutical industry.

  9. An electrochemical immunosensor based on chemical assembly of vertically aligned carbon nanotubes on carbon substrates for direct detection of the pesticide endosulfan in environmental water.

    PubMed

    Liu, Guozhen; Wang, Shuo; Liu, Jingquan; Song, Dandan

    2012-05-01

    A glassy carbon substrate was covalently modified with a mixed layer of 4-aminophenyl and phenyl via in situ electrografting of their aryldiazonium salts in acidic solutions. Single-walled carbon nanotubes (SWNTs) were covalently and vertically anchored on the electrode surface via the formation of amide bonds from the reaction between the amines located on the modified substrate and the carboxylic groups at the ends of the nanotubes. Ferrocenedimethylamine (FDMA) was subsequently attached to the ends of SWNTs through amide bonding followed by the attachment of an epitope, i.e., endosulfan hapten to which an antibody would bind. Association or dissociation of the antibody with the sensing interface causes a modulation of the ferrocene electrochemistry. Antibody-complexed electrodes were exposed to samples containing spiked endosulfan (unbound target analyte) in environment water and interrogated using the square wave voltammetry (SWV) technique. The modified sensing surfaces were characterized by atomic force microscopy, XPS, and electrochemistry. The fabricated electrochemical immunosensor can be successfully used for the detection of endosulfan over the range of 0.01-20 ppb by a displacement assay. The lowest detection limit of this immunosensor is 0.01 ppb endosulfan in 50 mM phosphate buffer at pH 7.0.

  10. A novel lable-free electrochemical immunosensor for carcinoembryonic antigen based on gold nanoparticles-thionine-reduced graphene oxide nanocomposite film modified glassy carbon electrode.

    PubMed

    Kong, Fen-Ying; Xu, Mao-Tian; Xu, Jing-Juan; Chen, Hong-Yuan

    2011-10-15

    In this paper, gold nanoparticle-thionine-reduced graphene oxide (GNP-THi-GR) nanocomposites were prepared to design a label-free immunosensor for the sensitive detection of carcinoembryonic antigen (CEA). The nanocomposites with good biocompatibility, excellent redox electrochemical activity and large surface area were coated onto the glassy carbon electrode (GCE) surface and then CEA antibody (anti-CEA) was immobilized on the electrode to construct the immunosensor. The morphologies and electrochemistry of the formed nanocomposites were investigated by using scanning electron microscopy (SEM), ultraviolet-visible (UV-vis) spectrometry, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). CV and differential pulse voltammetry (DPV) studies demonstrated that the formation of antibody-antigen complexes decreased the peak current of THi in the GNP-THi-GR nanocomposites. The decreased currents were proportional to the CEA concentration in the range of 10-500 pg/mL with a detection limit of 4 pg/mL. The proposed method was simple, fast and inexpensive for the determination of CEA at very low levels.

  11. An Immunosensor Based on Antibody Binding Fragments Attached to Gold Nanoparticles for the Detection of Peptides Derived from Avian Influenza Hemagglutinin H5

    PubMed Central

    Jarocka, Urszula; Sawicka, Róża; Góra-Sochacka, Anna; Sirko, Agnieszka; Zagórski-Ostoja, Włodzimierz; Radecki, Jerzy; Radecka, Hanna

    2014-01-01

    This paper concerns the development of an immunosensor for detection of peptides derived from avian influenza hemagglutinin H5. Its preparation consists of successive gold electrode modification steps: (i) modification with 1,6-hexanedithiol and gold colloidal nanoparticles; (ii) immobilization of antibody-binding fragments (Fab') of anti-hemagglutinin H5 monoclonal antibodies Mab 6-9-1 via S-Au covalent bonds; and (iii) covering the remaining free space on the electrode surfaces with bovine serum albumin. The interactions between Fab' fragments and hemagglutinin (HA) variants have been explored with electrochemical impedance spectroscopy (EIS) in the presence of [Fe(CN)6]3−/4− as an electroactive marker. The immunosensor was able to recognize three different His-tagged variants of recombinant hemagglutinin from H5N1 viruses: H1 subunit (17–340 residues) of A/swan/Poland/305-135V08/2006, the long HA (17–530 residues) A/Bar-headed Goose/Qinghai/12/2005 and H1 subunit (1–345 residues) of A/Vietnam/1194/2004. The strongest response has been observed for the long variant with detection limit of 2.2 pg/mL and dynamic range from 4.0 to 20.0 pg/mL. PMID:25157550

  12. Visible-light driven label-free photoelectrochemical immunosensor based on TiO2/S-BiVO4@Ag2S nanocomposites for sensitive detection OTA.

    PubMed

    Feng, Jinhui; Li, Yueyun; Gao, Zengqiang; Lv, Hui; Zhang, Xiaobo; Fan, Dawei; Wei, Qin

    2018-01-15

    A label-free photoelectrochemical (PEC) platform with high visible-light activity for quantitative detection of the ochratoxin A (OTA) was developed by assembly of Ag2S nanoparticles (NPs) sensitized on titanium dioxide/red blood cell-like shape bismuth vanadate (TiO2/S-BiVO4) electrode via layer-by-layer (LBL) strategy. In this protocol, ascorbic acid was used as an efficient electron donor for scavenging photo-generated holes and inhibiting light driven electron-hole pair recombination. TiO2 has good photoelectric activity and large surface area. The S-BiVO4 with porous structure surfaces can contribute to the high photocurrent intensity under visible-light irradiation. Moreover, the Ag2S NPs were in-situ growth on surfaces of thioglycolic acid modified S-BiVO4, which enhanced photocurrent response and further improved the photocurrent conversion efficiency. Under optimal conditions, the PEC immunosensor exhibited a wide linear concentration range from 5pgmL(-1) to 750ngmL(-1), with a low detection limit of 1.7pgmL(-1) (S/N = 3) for OTA. Additionally, the designed immunosensor was performed with good stability, reproducibility and selectivity, thus opening up a new promising PEC platform for some other small molecules analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. An ultrasensitive electrochemical immunosensor based on the synergistic effect of quaternary Cu2SnZnS4 NCs and cyclodextrin-functionalized graphene.

    PubMed

    Liu, Lei; Zhang, Yihe; Du, Ruifeng; Li, Jinhong; Yu, Xuelian

    2017-02-27

    In this study, highly monodispersed Cu2SnZnS4 NCs with a quasi-spherical structure were prepared to construct a sandwich-type electrochemical immunosensor for alpha-fetoprotein detection. Quaternary Cu2SnZnS4 NCs as novel biomimetic catalysts show an efficient intrinsic peroxidase-like activity for H2O2 reduction. This excellent catalytic activity is ascribed to the higher electroconductivity than those of the binary Cu2S and ternary Cu2SnS3 NCs. Moreover, β-cyclodextrin-functionalized graphene sheets are used as substrate materials that can capture large amounts of primary antibodies due to host-guest interaction and high surface area. Under the optimized conditions, the electrochemical immunosensor exhibites a wide working range from 0.5 pg mL(-1) to 10 ng mL(-1) and a detection limit of 0.16 pg mL(-1) at a signal-to-noise ratio of 3. Good sensitivity, reproducibility, and stability demonstrate its potential application in clinical diagnostics.

  14. An ultrasensitive sandwich-type electrochemical immunosensor based on signal amplification strategy of gold nanoparticles functionalized magnetic multi-walled carbon nanotubes loaded with lead ions.

    PubMed

    Li, Faying; Han, Jian; Jiang, Liping; Wang, Yulan; Li, Yueyun; Dong, Yunhui; Wei, Qin

    2015-06-15

    In this study, a novel and ultrasensitive sandwich-type electrochemical immunosensor was prepared for the quantitative detection of alpha fetoprotein (AFP), a well-known hepatocellular carcinoma biomarker. Gold nanoparticles (Au NPs) functionalized magnetic multi-walled carbon nanotubes (MWCNTs-Fe3O4) were prepared and utilized for the adsorption of lead ions (Pb(2+)) and the secondary antibodies (Ab2). The resultant nanocomposites (Pb(2+)@Au@MWCNTs-Fe3O4) were used as the label for signal amplification, showing better electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2) than MWCNTs, MWCNTs-Fe3O4 or Au@MWCNTs-Fe3O4 due to the synergetic effect presented in Pb(2+)@Au@MWCNTs-Fe3O4. Moreover, Au NPs were electrodeposited on the surface of glassy carbon electrode (GCE) for the effective immobilization of primary antibodies (Ab1). Under the optimal conditions, a linear range from 10 fg/mL to 100 ng/mL and a detection limit of 3.33 fg/mL were obtained. The proposed electrochemical sandwich-type immunosensor shows high sensitivity, good selectivity and stability for the quantitative detection of AFP, holding a great potential in clinical and diagnostic applications.

  15. Acceleration sensing based on graphene resonator

    NASA Astrophysics Data System (ADS)

    Jie, Wenbin; Hu, Feng; Wang, Xingshu; Qin, Shiqiao

    2017-02-01

    This paper is concerned with the acceleration sensing based on graphene resonator using finite-element software COMSOL Multiphysics. Based on the ordinary graphene resonator structure, a proof mass is attached to the surface of graphene sheet in order to sense acceleration and force more effectively. The rectangle-shaped gold proof mass is positioned at the center of the graphene sheet. Through COMSOL Multiphysics, the simulations about how the graphene sheet and mass' dimension affect resonance frequency were performed and proper size parameters for the graphene resonator were chosen. By adopting these parameters, the analysis about the resonance frequency's change responding to the acceleration or working force was carried out, which lays a foundation for further research of graphene resonator for acceleration sensing.

  16. Electrochemical immunosensor for carcinoembryonic antigen based on nanosilver-coated magnetic beads and gold-graphene nanolabels.

    PubMed

    Chen, Huafeng; Tang, Dianping; Zhang, Bing; Liu, Bingqian; Cui, Yuling; Chen, Guonan

    2012-03-15

    A novel redox-active magnetic nanostructure was synthesized by using a wet chemical method for high-efficiency electrochemical immunoassay of carcinoembryonic antigen (CEA, as a model analyte). The nanostructures based on the combination of a magnetic nanocore, a layer of electroactive poly(o-phenylenediamine) (PPD), and a silver metallic shell displayed good adsorption properties for the attachment of anti-CEA antibody selective to CEA. The magnetic nanostructure presented good redox behaviors to facilitate and modulate the way it was integrated into a magnetic carbon paste electrode. The assay was based on a sandwich-type immunoassay protocol by using nanogold-patterned graphene oxide nanoscales (AuNP-GO), conjugated with horseradish peroxidase-labeled anti-CEA, as secondary antibodies and biofunctionalized magnetic nanostructures as immunosensing probes. Under optimal conditions, the nanoparticle-based immunocomposites exhibited good electrochemical responses for the determination of CEA, and allowed the detection of CEA at a concentration as low as 1.0 pg mL(-1) at a signal-to-noise ratio of 3. In addition, the magnetic immunosensing had good reproducibility, and acceptable accuracy, and could be successfully applied for the detection of CEA in the clinical serum specimens. Significantly, by controlling the target biomolecules, this assay can be easily extended for use with other immunosensings, and thus represents a versatile design routine. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Chemiluminescent optical fiber immunosensor for detection of autoantibodies to ovarian and breast cancer-associated antigens.

    PubMed

    Salama, Orly; Herrmann, Sebastien; Tziknovsky, Alina; Piura, Benjamin; Meirovich, Michael; Trakht, Ilya; Reed, Brent; Lobel, Leslie I; Marks, Robert S

    2007-02-15

    We report herein the development of an optical fiber based chemiluminescent immunosensor for detection of the native autoimmune response to GIPC-1, a PDZ containing protein involved in regulation of G-protein signaling. The recombinant protein GIPC-1 was expressed in bacteria, purified, refolded and conjugated to the tip of an optical fiber. A human monoclonal 27.B1 IgM isolated from a breast cancer patient, which targets the GIPC-1 protein, was used for calibration of the immunosensor and was detected down to a concentration of 30 pg/ml. We determined that the fiber-optic immunosensor had a detection limit 50 times lower than chemiluminescent ELISA, and approximately 500 times lower than colorimetric ELISA. In addition, sera from 11 ovarian cancer patients, 22 breast cancer patients and asymptomatic controls were tested for the presence of IgM anti-GIPC-1 autoantibodies in their serum using the two methods. The immunosensor assay detected 54% and 77% GIPC-1 positive sera within ovarian and breast cancer patients, respectively, as compared to chemiluminescent ELISA, which only detected 18% and 27%, respectively. We envision that this immunosensor may serve as a diagnostic tool for screening women for ovarian and breast cancer at an early stage, thus increasing their chance of survival.

  18. A Label-Free Immunosensor for IgG Based on an Extended-Gate Type Organic Field Effect Transistor

    PubMed Central

    Minamiki, Tsukuru; Minami, Tsuyoshi; Kurita, Ryoji; Niwa, Osamu; Wakida, Shin-ichi; Fukuda, Kenjiro; Kumaki, Daisuke; Tokito, Shizuo

    2014-01-01

    A novel biosensor for immunoglobulin G (IgG) detection based on an extended-gate type organic field effect transistor (OFET) has been developed that possesses an anti-IgG antibody on its extended-gate electrode and can be operated below 3 V. The titration results from the target IgG in the presence of a bovine serum albumin interferent, clearly exhibiting a negative shift in the OFET transfer curve with increasing IgG concentration. This is presumed to be due an interaction between target IgG and the immobilized anti-IgG antibody on the extended-gate electrode. As a result, a linear range from 0 to 10 µg/mL was achieved with a relatively low detection limit of 0.62 µg/mL (=4 nM). We believe that these results open up opportunities for applying extended-gate-type OFETs to immunosensing. PMID:28788216

  19. A One-Step Homogeneous Sandwich Immunosensor for Salmonella Detection Based on Magnetic Nanoparticles (MNPs) and Quantum Dots (QDs)

    PubMed Central

    Kuang, Hua; Cui, Gang; Chen, Xiujin; Yin, Honghong; Yong, Qianqian; Xu, Liguang; Peng, Chifang; Wang, Libing; Xu, Chuanlai

    2013-01-01

    Simple immuno-magnetic separation tandem fluorescent probes based on quantum dots-antibody (QDs-Ab) were developed to detect Salmonella with sensitivity of 500 cfu mL−1. With two monoclonal antibodies, which recognize different antigenic determinant on the surface of Salmonella, we prepared antibody-coated magnetic nanoparticles (MNPs) and conjugates of QDs-Ab. The immune-magnetic beads were verified with high enrichment efficiency for Salmonella (90%). A sandwich structure formed if the Salmonella solution was mixed together with immune-beads and QDs-Ab, and the fluorescent single from QDs was related to the amount of Salmonella. A linear response between fluorescence intensity and various concentrations of Salmonella (2.5 × 103 to 1.95 × 108 cfu mL−1) were observed with this proposed method. The total assay time for Salmonella was 30 min, and no cross-reaction to other microbial strains, such as Staphylococcus aureus, Escherichia coli (E. coli) and Escherichia coli O157:H7 (E. coli O157:H7), were found using this detection system. All our results showed that the simple homogeneous immunoassay could be applied in Salmonella screening without time-consuming extra-enrichment of bacteria. PMID:23609493

  20. Antibody-conjugated gold nanoparticle-based immunosensor for ultra-sensitive detection of troponin-T.

    PubMed

    Jacobs, Michael; Panneer Selvam, Anjan; Craven, Jon Engel; Prasad, Shalini

    2014-12-01

    The technology presented in this study demonstrates the feasibility of integrating nanostructures onto the surface of an electrical platform to achieve enhanced detection of the cardiac biomarker, troponin-T. A polymer microcontact printing technique was modified using printed circuit boards as molds for the application of gold nanoparticles onto microelectrode-patterned glass substrates. The microelectrodes were designed to support electrical impedance spectroscopy measurements and fabricated using standard photolithography methods. Capture antibodies specific to troponin-T were functionalized onto the surface of gold nanoparticles by using a thiol-based cross-linking molecule. The antibody-conjugated gold nanoparticles were stamped onto the electrodes using a matching pattern imprinted onto an elastomeric mold. As a control to validate the efficacy of the nanotextured surface on the glass substrate, an electroplated printed circuit board was also used. The incorporation of gold nanoparticles showed significant amplification of the electro-ionic signals generated through binding of the antigen to its capture antibody. Enhanced sensitivity was demonstrated through detection of the target biomarker in the femtogram per milliliter range in buffer solution and biological media. In the absence of gold nanoparticles, the sensor demonstrated detection of troponin-T at higher concentration points. This study illustrates a robust method for developing a more sensitive, label-free biosensor.

  1. Surface Plasmon Resonance Investigations of Bioselective Element Based on the Recombinant Protein A for Immunoglobulin Detection.

    PubMed

    Bakhmachuk, A; Gorbatiuk, O; Rachkov, A; Dons'koi, B; Khristosenko, R; Ushenin, I; Peshkova, V; Soldatkin, A

    2017-12-01

    The developed surface plasmon resonance (SPR) biosensor based on the recombinant Staphylococcal protein A with an additional cysteine residue (SPA-Cys) used as a biorecognition component showed a good selectivity and sensitivity for the immunoglobulin detection. The developed biosensor with SPA-Cys-based bioselective element can also be used as a first step of immunosensor creation. The successful immobilization of SPA-Cys on the nanolayer gold sensor surface of the SPR spectrometer was performed. The efficiency of blocking nonspecific sorption sites on the sensor surface with milk proteins, gelatin, BSA, and HSA was studied, and a rather high efficiency of using gelatin was confirmed. The SPR biosensor selectively interacted with IgG and did not interact with the control proteins. The linear dependence of the sensor response on the IgG concentration in the range from 2 to 10 μg/ml was shown. Using the calibration curve, the IgG concentration was measured in the model samples. The determined concentrations are in good agreement (r (2) = 0.97) with the given concentration of IgG.

  2. Surface Plasmon Resonance Investigations of Bioselective Element Based on the Recombinant Protein A for Immunoglobulin Detection

    NASA Astrophysics Data System (ADS)

    Bakhmachuk, A.; Gorbatiuk, O.; Rachkov, A.; Dons'koi, B.; Khristosenko, R.; Ushenin, I.; Peshkova, V.; Soldatkin, A.

    2017-02-01

    The developed surface plasmon resonance (SPR) biosensor based on the recombinant Staphylococcal protein A with an additional cysteine residue (SPA-Cys) used as a biorecognition component showed a good selectivity and sensitivity for the immunoglobulin detection. The developed biosensor with SPA-Cys-based bioselective element can also be used as a first step of immunosensor creation. The successful immobilization of SPA-Cys on the nanolayer gold sensor surface of the SPR spectrometer was performed. The efficiency of blocking nonspecific sorption sites on the sensor surface with milk proteins, gelatin, BSA, and HSA was studied, and a rather high efficiency of using gelatin was confirmed. The SPR biosensor selectively interacted with IgG and did not interact with the control proteins. The linear dependence of the sensor response on the IgG concentration in the range from 2 to 10 μg/ml was shown. Using the calibration curve, the IgG concentration was measured in the model samples. The determined concentrations are in good agreement ( r 2 = 0.97) with the given concentration of IgG.

  3. Detection of explosives in a dynamic marine environment using a moored TNT immunosensor.

    PubMed

    Charles, Paul T; Adams, André A; Deschamps, Jeffrey R; Veitch, Scott; Hanson, Al; Kusterbeck, Anne W

    2014-02-27

    A field demonstration and longevity assessment for long-term monitoring of the explosive 2,4,6-trinitrotoluene (TNT) in a marine environment using an anti-TNT microfluidic immunosensor is described. The TNT immunosensor is comprised of a microfluidic device with 39 parallel microchannels (2.5 cm × 250 µm × 500 µm, L × W × D) fabricated in poly(methylmethacrylate) (PMMA), then chemically functionalized with antibodies possessing a high affinity for TNT. Synthesized fluorescence reporter complexes used in a displacement-based assay format were used for TNT identification. For field deployment the TNT immunosensor was configured onto a submersible moored steel frame along with frame controller, pumps and TNT plume generator and deployed pier side for intermittent plume sampling of TNT (1h increments). Under varying current and tidal conditions trace levels of TNT in natural seawater were detected over an extended period (>18 h). Overnight operation and data recording was monitored via a web interface.

  4. Antigen-antibody interaction from quartz crystal microbalance immunosensors based on magnetic CoFe2O4/SiO2 composite nanoparticle-functionalized biomimetic interface.

    PubMed

    Chen, Zai-Gang; Tang, Dian-Yong

    2007-07-01

    A new quartz crystal microbalance immunoassay for the detection of carcinoembryonic antigen (CEA) was developed by means of immobilizing anti-CEA onto magnetic CoFe2O4/SiO2 composite nanoparticles-functionalized biomimetic interface. Under optimal conditions, the frequency shift was proportional to the CEA concentration in the range of 2.5-55 ng/mL with a detection limit of 0.5 ng/mL at a signal-to-noise ratio of 3. Moreover, the immunosensor system showed an acceptable reproducibility and stability. Clinical serum specimens were assayed with this method, and the results were in acceptable agreement with those obtained from ELISA. Compared with the conventional ELISA assay, the proposed immunoassay system was simple and rapid without multiple labeling and separation steps. Importantly, the developed immunoassay protocol could be further extended for the determination of other antigens.

  5. Quartz crystal microbalance immunosensors for environmental monitoring.

    PubMed

    Kurosawa, Shigeru; Park, Jong-Won; Aizawa, Hidenobu; Wakida, Shin-Ichi; Tao, Hiroaki; Ishihara, Kazuhiko

    2006-10-15

    This paper presents discussion of quartz crystal microbalance (QCM) immunosensors for environmental monitoring. Factors limiting the practical application of antibodies to analytical problems are also presented. Among several candidates for the QCM immunosensor device, selected QCM devices and oscillating circuits were tested thoroughly and developed to obtain highly stable and sensitive frequency signals. The biointerface of QCM immunosensor was designed and controlled to immobilize antibody on the QCM surface, to reduce non-specific binding and to suppress denaturation of immobilizing antibody by self-assembled monolayer technique and artificial phospholipid (2-methacryloyloxyethyl phosphorylcholine (MPC)) polymer. MPC polymer as a antibody-stabilizing reagent was added to reduce non-specific binding of the antigen solution and stabilize the immunologic activity of the antibody-immobilized QCM. In addition, it provides examples for detection and quantitation of environmental samples using QCM immunosensors. The analytical results for fly ash extracted samples of dioxins using the QCM immunosensor indicated a good relationship with GC/MS methods. The integrating protocols of the competitive immunoassay and signal-enhancing step are for detecting low molecular analytes with extremely low detection limits using an QCM immunosensor. Furthermore, its detect limitation was extended from 0.1 to 0.01 ng/ml by the signal-enhancing step when the anti-bisphenol-A antibody conjugated MPC polymeric nanoparticles was used. The QCM immunosensor method has demonstrated its effectiveness as an alternative screening method for environmental monitoring because these results were compared with results obtained through environmental monitoring methods such as ELISA and GC/MS.

  6. Photoelectrochemical Immunosensor for Detection of Carcinoembryonic Antigen Based on 2D TiO2 Nanosheets and Carboxylated Graphitic Carbon Nitride

    PubMed Central

    Wang, Huan; Wang, Yaoguang; Zhang, Yong; Wang, Qi; Ren, Xiang; Wu, Dan; Wei, Qin

    2016-01-01

    Carcinoembryonic antigen (CEA) was used as the model, an ultrasensitive label-free photoelectrochemical immunosensor was developed using 2D TiO2 nanosheets and carboxylated graphitic carbon nitride (g-C3N4) as photoactive materials and ascorbic acid as an efficient electron donor. 2D TiO2 nanosheets was sythsized by surfactant self-assembly method and proved to have higher photoelectrochemical signals than TiO2 nanoparticles. Firstly, carboxylated g-C3N4 could be attached to 2D TiO2 nanosheets through the bond formed between carboxyl group of carboxylated g-C3N4 and TiO2. And the photocurrent of g-C3N4/TiO2 drastically enhances compared to carboxylated g-C3N4 and TiO2. Then, antibody of CEA was bonded to TiO2 through the dentate bond formed between carboxyl group of anti-CEA and TiO2, leading to the decrease of the photocurrents. As proven by PEC experiments and electrochemical impedance spectroscopy (EIS) analysis, the fabrication process of the immunosensor is successful. Under the optimal conditions, the intensity decreased linearly with CEA concentration in the range of 0.01~10 ng/mL. The detection limit is 2.1 pg/mL. The work provides an effective method for the detection of tumor markers and can be extended for the application in food safety and environmental monitoring analysis. PMID:27263659

  7. Planar waveguide optical immunosensors

    NASA Astrophysics Data System (ADS)

    Choquette, Steven J.; Locascio-Brown, Laurie E.; Durst, Richard A.

    1991-03-01

    Monoclonal antibodies were covalently bonded to the surfaces of planar waveguides to confer immunoreacth''ity. Silver-ion diffused waveguides were used to measure theophylline concentrations in a fluorescence immunoassay and silicon nitride waveguides were used to detect theophylline in an absorbance-based immunoassay. Liposomes were employed in both assays as the optically detectable label in a competitive reaction to monitor antigen-antibody complexation. Regeneration of the active antibody site will be discussed.

  8. DNA-probe-target interaction based detection of Brucella melitensis by using surface plasmon resonance.

    PubMed

    Sikarwar, Bhavna; Singh, Virendra V; Sharma, Pushpendra K; Kumar, Ashu; Thavaselvam, Duraipandian; Boopathi, Mannan; Singh, Beer; Jaiswal, Yogesh K

    2017-01-15

    Surface plasmon resonance (SPR) immunosensor using 4-mercaptobenzoic acid (4-MBA) modified gold (4-MBA/Au) SPR chip was developed first time for the detection of Brucella melitensis (B. melitensis) based on the screening of its complementary DNA target by using two different newly designed DNA probes of IS711 gene. Herein, interaction between DNA probes and target molecule are also investigated and result revealed that the interaction is spontaneous. The kinetics and thermodynamic results derived from the experimental data showed that the interaction between complementary DNA targets and probe 1 is more effective than that of probe 2. Equilibrium dissociation constant (KD) and maximum binding capacity of analyte (Bmax) values for the interaction of complementary DNA target with the immobilized DNA probes were calculated by using kinetic evaluation software, and found to be 15.3 pM (KD) and 81.02m° (Bmax) with probe 1 and 54.9pM and 55.29m° (Bmax), respectively. Moreover, real serum samples analysis were also carried out using immobilized probe 1 and probe 2 with SPR which showed the applicability of this methodology and provides an alternative way for the detection of B. melitensis in less than 10min. This remarkable sensing response of present methodology offer a real time and label free detection of biological warfare agent and provide an opportunity to make miniaturized sensor, indicating considerable promise for diverse environmental, bio-defence, clinical diagnostics, food safety, water and security applications.

  9. Electrochemical immunosensors for Salmonella detection in food.

    PubMed

    Melo, Airis Maria Araújo; Alexandre, Dalila L; Furtado, Roselayne F; Borges, Maria F; Figueiredo, Evânia Altina T; Biswas, Atanu; Cheng, Huai N; Alves, Carlúcio R

    2016-06-01

    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 time possible, conventional methods may take several days to produce a diagnosis. Salmonella spp. is the major cause of foodborne diseases worldwide and its absence is a requirement of the health authorities. Biosensors are bioelectronic devices, comprising bioreceptor molecules and transducer elements, able to detect analytes (chemical and/or biological species) rapidly and quantitatively. Electrochemical immunosensors use antibody molecules as bioreceptors and an electrochemical transducer. These devices have been widely used for pathogen detection at low cost. There are four main techniques for electrochemical immunosensors: amperometric, impedimetric, conductometric, and potentiometric. Almost all types of immunosensors are applicable to Salmonella detection. This article reviews the developments and the applications of electrochemical immunosensors for Salmonella detection, particularly the advantages of each specific technique. Immunosensors serve as exciting alternatives to conventional methods, allowing "real-time" and multiple analyses that are essential characteristics for pathogen detection and much desired in health and safety control in the food industry.

  10. Graphene-Ruthenium(II) complex composites for sensitive ECL immunosensors.

    PubMed

    Xiao, Fang-Nan; Wang, Min; Wang, Feng-Bin; Xia, Xing-Hua

    2014-02-26

    Non-covalent modification method has been proven as an effective strategy for enhancing the chemical properties of graphene while the structure and electronic properties of graphene can be retained. This work describes a novel strategy to fabricate a solid-state electrochemiluminescent (ECL) immunosensor based on ruthenium(II) complex/3,4,9,10-perylenetetracarboxylic acid (PTCA)/graphene nanocomposites (Ru-PTCA/G) for sensitive detection of α-fetoprotein (AFP). It is found that immobilization of PTCA and reduction of GO can be simultaneously achieved in one-pot synthesis method under alkaline condition and moderate temperature, forming PTCA/G nanocomposites. Further covalent attachment of ruthenium(II) complex to the PTCA assembled on graphene sheets produces the functional Ru-PTCA/G nanocomposites which show good electrochemical activity and ca. 21 times higher luminescence quantum efficiency than the adsorbed derivative ruthenium(II) complex. The Ru-PTCA/G nanocomposites based solid-state ECL sensor exhibits high stability toward the determination of tripropylamine (TPA) coreactant. In addition, a new ECL immunosensor based on steric hindrance effect is fabricated by cross-linking α-fetoprotein antibody (anti-AFP) with chitosan covered on Ru-PTCA/G composites modified electrode for detection of cancer biomarker AFP. This ECL immunosensor shows an extremely sensitive response to AFP in a linear range of 5 pg·mL(-1) -10 ng·mL(-1) with a detection limit of 0.2 pg·mL(-1) . The present approach is effective for various molecules immobilization and may become a promising technique for biomolecular detection.

  11. Reconfigurable optical routers based on Coupled Resonator Induced Transparency resonances.

    PubMed

    Mancinelli, M; Bettotti, P; Fedeli, J M; Pavesi, L

    2012-10-08

    The interferometric coupling of pairs of resonators in a resonator sequence generates coupled ring induced transparency (CRIT) resonances. These have quality factors an order of magnitude greater than those of single resonators. We show that it is possible to engineer CRIT resonances in tapered SCISSOR (Side Coupled Integrated Space Sequence of Resonator) to realize fast and efficient reconfigurable optical switches and routers handling several channels while keeping single channel addressing capabilities. Tapered SCISSORs are fabricated in silicon-on-insulator technology. Furthermore, tapered SCISSORs show multiple-channel switching behavior that can be exploited in DWDM applications.

  12. Nanoparticle Labels/ Electrochemical Immunosensor for Detection of Biomarkers

    SciTech Connect

    Liu, Guodong; Wang, Jun; Lin, Yuehe

    2006-06-01

    A sensitive electrochemical immunosensor based on poly(guanine) functionalized silica nanoparticle label has been developed for the detection of protein biomarker, biomarker recombinant human tumor necrosis factor-a(TNF-a).This method is simple, selective, and reproducible for trace biomarker analysis. A remarkable LOD has been achieved through dual signal amplification by poly[G] functionalized silica NPs and catalytic guanine oxidation. The work demonstrates the feasibility of developing an inexpensive, sensitive, and portable device for multiplexed diagnoses of different protein biomarkers.

  13. Electrochemical Impedance Immunosensor Based on Self-Assembled Monolayers for Rapid Detection of Escherichia coli O157:H7 with Signal Amplification Using Lectin.

    PubMed

    Li, Zhanming; Fu, Yingchun; Fang, Weihuan; Li, Yanbin

    2015-08-05

    Escherichia coli O157:H7 is a predominant foodborne pathogen with severe pathogenicity, leading to increasing attention given to rapid and sensitive detection. Herein, we propose an impedance biosensor using new kinds of screen-printed interdigitated microelectrodes (SPIMs) and wheat germ agglutinin (WGA) for signal amplification to detect E. coli O157:H7 with high sensitivity and time-efficiency. The SPIMs integrate the high sensitivity and short response time of the interdigitated electrodes and the low cost of the screen-printed electrodes. Self-assembling of bi-functional 3-dithiobis-(sulfosuccinimidyl-propionate) (DTSP) on the SPIMs was investigated and was proved to be able to improve adsorption quantity and stability of biomaterials. WGA was further adopted to enhance the signal taking advantage of the abundant lectin-binding sites on the bacteria surface. The immunosensor exhibited a detection limit of 102 cfu·mL(-1), with a linear detection range from 10(2) to 10(7) cfu·mL(-1) (r2 = 0.98). The total detection time was less than 1 h, showing its comparable sensitivity and rapid response. Furthermore, the low cost of one SPIM significantly reduced the detection cost of the biosensor. The biosensor may have great promise in food safety analysis and lead to a portable biosensing system for routine monitoring of foodborne pathogens.

  14. Multiplexed enzyme-free electrochemical immunosensor based on ZnO nanorods modified reduced graphene oxide-paper electrode and silver deposition-induced signal amplification strategy.

    PubMed

    Sun, Guoqiang; Zhang, Lina; Zhang, Yan; Yang, Hongmei; Ma, Chao; Ge, Shenguang; Yan, Mei; Yu, Jinghua; Song, Xianrang

    2015-09-15

    Herein, an origami multiplexed enzyme-free electrochemical (EC) immunodevice is developed for the first time. Typically, ZnO nanorods (ZNRs) modified reduced graphene oxide (rGO)-paper electrode is used as a sensor platform, in which rGO improves the electronic transmission rate and ZNRs provide abundant sites for capture probes binding. Furthermore, by combining the large surface area of rGO and high catalytic activity of bovine serum protein (BSA)-stabilized silver nanoparticles (Ag@BSA) toward H2O2 reduction, rGO/Ag@BSA composites can be used as an excellent signal labels. The current signal is generated from the reduction of H2O2 and further amplified by a subsequent signal labels-promoted deposition of silver. Under optimal conditions, the proposed immunoassays exhibit excellent precision, high sensitivity and a wide linear range of 0.002-120 mIU mL(-1) for human chorionic gonadotropin, 0.001-110 ng mL(-1) for prostate-specific antigen, and 0.001-100 ng mL(-1) for carcinoembryonic antigen. The results for real sample analysis demonstrate that the newly constructed immunosensor arrays provide a simple and cost-effective method for clinical applications.

  15. Electrochemiluminescence immunosensor based on multifunctional luminol-capped AuNPs@Fe3O4 nanocomposite for the detection of mucin-1.

    PubMed

    Wang, Jing-Xi; Zhuo, Ying; Zhou, Ying; Yuan, Ruo; Chai, Ya-Qin

    2015-09-15

    In this work, a novel and multifunctional nanocomposite of luminol capped gold modified Fe3O4 (Lu-AuNPs@Fe3O4) was utilized as the carrier of secondary antibody (Ab2) to fabricate a sandwiched electrochemiluminescence (ECL) immunosensor for ultrasensitive detection of mucin-1 (MUC1). Herein, the luminol capped gold nanoparticles (Lu-AuNPs) were synthesized with HAuCl4 and luminol by the help of NaBH4 at room temperature, and then Lu-AuNPs were adsorbed on the Fe3O4 magnetic nanoparticles (MNPs) to form the nanocomposite of Lu-AuNPs@Fe3O4 via electrostatic interaction. Fe3O4 MNPs in Lu-AuNPs@Fe3O4 exhibited excellent conductivity and admirable catalytic activity in H2O2 decomposition, which could enhance the ECL efficiency of luminol-H2O2 system. In addition, the substrates of gold coated ZnO nanoparticles (AuNPs@ZnO), providing large specific surface areas for primary antibody (Ab1) capturing, were modified on the electrode. As a result, a wide linear range of 7 orders of magnitude from 10 fg/mL to 10 ng/mL was obtained with an ultralow detection limit of 4.5 fg/mL for MUC1. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Electrochemical immunosensor for N6-methyladenosine detection in human cell lines based on biotin-streptavidin system and silver-SiO2 signal amplification.

    PubMed

    Yin, Huanshun; Wang, Haiyan; Jiang, Wenjing; Zhou, Yunlei; Ai, Shiyun

    2017-04-15

    N6-methyladenosine (m6A), a kind of RNA methylation form and important epigenetic event, plays crucial roles in many biological progresses. Thus it is essential to quantitatively detect m6A in complicated biological samples. Herein, a simple and sensitive electrochemical method was developed for m6A detection using N6-methyladenosine-5'-triphosphate (m6ATP) as detection target molecule. In this detection strategy, anti-m6A antibody was selected as m6A recognition and capture reagent, silver nanoparticles and amine-PEG3-biotin functionalized SiO2 nanospheres (Ag@SiO2) was prepared and used as signal amplification label, and phos-tag-biotin played a vital role of "bridge" to link m6ATP and Ag@SiO2 through the two forms of specific interaction between phosphate group of m6ATP and phos-tag, biotin and streptavidin, respectively. Under the optimal experimental conditions, the immunosensor presented a wide linear range from 0.2 to 500nM and a low detection limit of 0.078nM (S/N=3). The reproducibility and specificity were acceptable. Moreover, the developed method was also validated for detect m6A content in human cell lines. Importantly, this detection strategy provides a promising immunodetection platform for ribonucleotides and deoxyribonucleotides with the advantages of simplicity, low-costing, specificity and sensitivity.

  17. Label-Free 3D Ag Nanoflower-Based Electrochemical Immunosensor for the Detection of Escherichia coli O157:H7 Pathogens

    NASA Astrophysics Data System (ADS)

    Huang, He; Liu, Minghuan; Wang, Xiangsheng; Zhang, Wenjie; Yang, Da-Peng; Cui, Lianhua; Wang, Xiansong

    2016-11-01

    It is highly desirable to develop a rapid and simple method to detect pathogens. Combining nanomaterials with electrochemical techniques is an efficient way for pathogen detection. Herein, a novel 3D Ag nanoflower was prepared via a biomineralization method by using bovine serum albumin (BSA) as a template. It was adopted as a sensing interface to construct an electrochemical bacteria immunosensor for the rapid detection of foodborne pathogens Escherichia coli ( E. coli) O157:H7. Bacterial antibody was immobilized onto the surface of Ag nanoflowers through covalent conjugation. Electrochemical impedance spectroscopy (EIS) was used to detect and validate the resistance changes, where [Fe(CN)6]3-/4- acted as the redox probe. A linear relation between R et and E. coli concentration was obtained in the E. coli concentration range of 3.0 × 102-3.0 × 108 cfu mL-1. The as-prepared biosensor gave rise to an obvious response to E. coli but had no distinct response to Cronobacter sakazakii, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus albus, Lactobacillus easei, and Shigella flexneri, revealing a high selectivity for the detection of the pathogens down to 100 cfu mL-1 in a short time. We believe that this BSA-conjugated 3D Ag nanoflowers could be used as a powerful interface material with good conductivity and biocompatibility for improving pathogen detection and treatment in the field of medicine, environment, and food safety.

  18. Building of an immunosensor: how can the composition and structure of the thiol attachment layer affect the immunosensor efficiency?

    PubMed

    Briand, Elisabeth; Salmain, Michèle; Herry, Jean-Marie; Perrot, Hubert; Compère, Chantal; Pradier, Claire-Marie

    2006-09-15

    Immunosensors, based on the immobilization of a model rabbit antibody on mixed self-assembled monolayers and Protein A as a linking agent on gold transducers, were elaborated and characterized at each step by modulated polarization-infrared spectroscopy (PM-IRRAS) and occasionally by atomic force microscopy (AFM) and quartz crystal microbalance (QCM). By testing two different mixed SAMs comprising 11-mercaptoundecanoic acid (MUA), together with either decanethiol (C9CH3) or mercaptohexanol (C6OH), the role of the chemical composition and structure of the antibody attachment layer upon the sensor performance was demonstrated.

  19. An electrochemical immunosensor for digoxin using core-shell gold coated magnetic nanoparticles as labels.

    PubMed

    Ahmadi, Anita; Shirazi, Hanieh; Pourbagher, Narges; Akbarzadeh, Abolfazl; Omidfar, Kobra

    2014-03-01

    A simple, sensitive, and low-cost immunosensor was designed for the detection of digoxin through core-shell gold coated magnetic nanoparticles (Fe3O4-Au-NPs) as an electrochemical label. Having had such a large potential for a variety of applications, Fe3O4-Au-NPs have attracted a considerable attention and are actively investigated recently. Digoxin is a cardiac glycoside which, at high level, can indicate an increased risk of toxicity. This new competitive electrochemical immunosensor was developed based on antigen-antibody reaction employing antigen (Ag) labeled Fe3O4-Au-NPs and PVA modified screen-printed carbon electrode surface in order to detect the serum digoxin. The structures of Fe3O4-Au-NPs were studied by transmission electron microscopy, X-ray diffraction and Fourier transformed infrared spectroscopy. Cyclic voltammetry and differential pulse voltammetry (DPV) were employed to determine the physicochemical and electrochemical properties of immunosensor. DPV was employed for quantitative detection of digoxin in biological samples. The developed immunosensor was capable to detect digoxin in the range from 0.5 to 5 ng mL(-1), with a detection limit as low as 0.05 ng mL(-1). The proposed method represented acceptable reproducibility, stability, and reliability for the rapid detection of digoxin in serum samples.

  20. Automated-immunosensor with centrifugal fluid valves for salivary cortisol measurement

    PubMed Central

    Yamaguchi, Masaki; Katagata, Hiroki; Tezuka, Yuki; Niwa, Daisuke; Shetty, Vivek

    2015-01-01

    Point-of-care measurement of the stress hormone cortisol will greatly facilitate the timely diagnosis and management of stress-related disorders. We describe an automated salivary cortisol immunosensor, incorporating centrifugal fluid valves and a disposable disc-chip that allows for truncated reporting of cortisol levels (<15 min). The performance characteristics of the immunosensor are optimized through select blocking agents to prevent the non-specific adsorption of proteins; immunoglobulin G (IgG) polymer for the pad and milk protein for the reservoirs and the flow channels. Incorporated centrifugal fluid valves allow for rapid and repeat washings to remove impurities from the saliva samples. An optical reader and laptop computer automate the immunoassay processes and provide easily accessible digital readouts of salivary cortisol measurements. Linear regression analysis of the calibration curve for the cortisol immunosensor showed 0.92 of coefficient of multiple determination, R2, and 38.7% of coefficient of variation, CV, for a range of salivary cortisol concentrations between 0.4 and 11.3 ng/mL. The receiver operating characteristic (ROC) curve analysis of human saliva samples indicate potential utility for discriminating stress disorders and underscore potential application of the biosensor in stress disorders. The performance of our salivary cortisol immunosensor approaches laboratory based tests and allows noninvasive, quantitative, and automated analysis of human salivary cortisol levels with reporting times compatible with point-of-care applications. PMID:26543818

  1. Automated-immunosensor with centrifugal fluid valves for salivary cortisol measurement.

    PubMed

    Yamaguchi, Masaki; Katagata, Hiroki; Tezuka, Yuki; Niwa, Daisuke; Shetty, Vivek

    2014-08-01

    Point-of-care measurement of the stress hormone cortisol will greatly facilitate the timely diagnosis and management of stress-related disorders. We describe an automated salivary cortisol immunosensor, incorporating centrifugal fluid valves and a disposable disc-chip that allows for truncated reporting of cortisol levels (<15 min). The performance characteristics of the immunosensor are optimized through select blocking agents to prevent the non-specific adsorption of proteins; immunoglobulin G (IgG) polymer for the pad and milk protein for the reservoirs and the flow channels. Incorporated centrifugal fluid valves allow for rapid and repeat washings to remove impurities from the saliva samples. An optical reader and laptop computer automate the immunoassay processes and provide easily accessible digital readouts of salivary cortisol measurements. Linear regression analysis of the calibration curve for the cortisol immunosensor showed 0.92 of coefficient of multiple determination, R(2), and 38.7% of coefficient of variation, CV, for a range of salivary cortisol concentrations between 0.4 and 11.3 ng/mL. The receiver operating characteristic (ROC) curve analysis of human saliva samples indicate potential utility for discriminating stress disorders and underscore potential application of the biosensor in stress disorders. The performance of our salivary cortisol immunosensor approaches laboratory based tests and allows noninvasive, quantitative, and automated analysis of human salivary cortisol levels with reporting times compatible with point-of-care applications.

  2. Electrochemical immunosensor for competitive detection of neuron specific enolase using functional carbon nanotubes and gold nanoprobe.

    PubMed

    Yu, Tianxiao; Cheng, Wei; Li, Qing; Luo, Caihui; Yan, Li; Zhang, Decai; Yin, Yibing; Ding, Shijia; Ju, Huangxian

    2012-05-15

    An electrochemical immunosensor for detection of neuron specific enolase (NSE) was designed by immobilizing NSE covalently functionalized single-walled carbon nanotubes (NSE-SWNTs) on a glassy carbon electrode. The NSE-SWNTs not only enhanced electrochemical signal but also presented abundant antigen domains for competitive immunological recognition to anti-NSE primary antibody and then gold nanoprobes labeled with alkaline phosphatase conjugated secondary antibody (AP-anti-IgG/AuNPs). The AP-anti-IgG/AuNPs exhibited highly catalytic activity toward enzyme substrate and significantly amplified the amperometric signal for target molecule detection. Based on the dual signal amplification of SWNTs and gold nanoprobe, the immunosensor could response down to 0.033 ng mL(-1) NSE with a linear range from 0.1 ng mL(-1) to 2 μg mL(-1), and showed acceptable precision and reproducibility. The designed immunosensor was amenable to direct quantification of target protein with a wide range of concentration in complex clinical serum specimens. The assay results were in a good agreement with the reference values. The proposed electrochemical immunosensor provided a pragmatic platform for convenient detection of tumor markers in clinical diagnosis. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Magnetic mesoporous organic-inorganic NiCo2O4 hybrid nanomaterials for electrochemical immunosensors.

    PubMed

    Li, Qunfang; Zeng, Lingxing; Wang, Jinchao; Tang, Dianping; Liu, Bingqian; Chen, Guonan; Wei, Mingdeng

    2011-04-01

    This study demonstrates a facile and feasible strategy toward the development of advanced electrochemical immunosensors based on chemically functionalized magnetic mesoporous organic-inorganic hybrid nanomaterials, and the preparation, characterization, and measurement of relevant properties of the immunosensor for detection of carcinoembryonic antigen (CEA, as a model analyte) in clinical immunoassays. The as-prepared nanomaterials composed of a magnetic mesoporous NiCo(2)O(4) nanosheet, an interlayer of Nafion/thionine organic molecules and a nanogold layer show good adsorption properties for the attachment of horseradish peroxidase-labeled secondary anti-CEA antibody (HRP-anti-CEA). With a sandwich-type immunoassay format, the functional bionanomaterials present good analytical properties to facilitate and modulate the way it was integrated onto the electrochemical immunosensors, and allows the detection of CEA at a concentration as low as 0.5 pg/mL. Significantly, the immunosensor could be easily regenerated by only using an external magnet without the need of any dissociated reagents. Importantly, the as-synthesized magnetic mesoporous NiCo(2)O(4) nanomaterials could be further extended for detection of other biomarkers or biocompounds.

  4. An electrochemical immunosensor for sensitive detection of Escherichia coli O157:H7 using C60 based biocompatible platform and enzyme functionalized Pt nanochains tracing tag.

    PubMed

    Li, Yan; Fang, Lichao; Cheng, Ping; Deng, Jun; Jiang, Lili; Huang, Hui; Zheng, Junsong

    2013-11-15

    A sensitive and efficient electrochemical immunosensor was designed for amperometric detection of heat-killed Escherichia coli O157:H7 (E. coli O157:H7). The immunosensing platform was first composed of fullerene (C60), ferrocene (Fc) and thiolated chitosan (CHI-SH) composite nano-layer which could offer rich -SH functional groups and maintain good biocompatibility. Then the Au nanoparticles coated SiO2 nanocomposites (Au-SiO2) were assembled on the CHI-SH/Fc/C60 composite. Next, the large amount of avidin (SA) was coated on the Au-SiO2 surface, which was used to immobilize biotinylated capture antibodies of E. coli O157:H7 (bio-Ab1) through the covalent reaction between biotin and avidin. With surface area enhancement by C60 and Au-SiO2, and directional immobilization by avidin-biotin system, the amount of immobilized bio-Ab1 can be enhanced obviously. For signal amplification, the glucose oxidase (GOD) loaded Pt nanochains (PtNCs) were used as tracing tag to label signal antibodies (Ab2). With a sandwich-type immunoreaction, the concentration volume of heat-killed E. coli O157:H7 ranged from 3.2 × 10(1) to 3.2 × 10(6)CFU/mL with a limit of detection down to 15 CFU/mL (S/N=3), which could be well accepted for early clinical detection. The studied system provides new opportunities, and might speed up disease diagnosis, treatment and prevention with pathogen.

  5. Sensitive Electrochemiluminescence Immunosensor for Detection of N-Acetyl-β-d-glucosaminidase Based on a "Light-Switch" Molecule Combined with DNA Dendrimer.

    PubMed

    Wang, Haijun; Yuan, Yali; Zhuo, Ying; Chai, Yaqin; Yuan, Ruo

    2016-06-07

    Here, a novel "light-switch" molecule of Ru (II) complex ([Ru(dcbpy)2dppz](2+)-DPEA) with self-enhanced electrochemiluminescence (ECL) property is proposed, which is almost nonemissive in aqueous solution but is brightly luminescent when it intercalates into DNA duplex. Owing to less energy loss and shorter electron-transfer distance, the intramolecular ECL reaction between the luminescent [Ru(dcbpy)2dppz](2+) and coreactive tertiary amine group in N,N-diisopropylethylenediamine (DPEA) makes the obtained "light-switch" molecule possess much higher light-switch efficiency compared with the traditional "light-switch" molecule. For increasing the loading amount and further enhancing the luminous efficiency of the "light-switch" molecule, biotin labeled DNA dendrimer (the fourth generation, G4) is prepared from Y-shape DNA by a step-by-step assembly strategy, which provides abundant intercalated sites for [Ru(dcbpy)2dppz](2+)-DPEA. Meanwhile, the obtained nanocomposite (G4-[Ru(dcbpy)2dppz](2+)-DPEA) could well bind with streptavidin labeled detection antibody (SA-Ab2) due to the existence of abundant biotin. Through sandwiched immunoreaction, an ECL immunosensor was fabricated for sensitive determination of N-acetyl-β-d-glucosaminidase (NAG), a typical biomarker for diabetic nephropathy (DN). The detemination linear range was 0.1 pg mL(-1) to 1 ng mL(-1), and the detection limit was 0.028 pg mL(-1). The developed strategy combining the ECL self-enhanced "light-switch" molecular and DNA nanotechnology offers an effective signal amplification mean and provides ample potential for further bioanalysis and clinical study.

  6. Aptasensors Based on Whispering Gallery Mode Resonators.

    PubMed

    Nunzi Conti, Gualtiero; Berneschi, Simome; Soria, Silvia

    2016-07-16

    In this paper, we review the literature on optical evanescent field sensing in resonant cavities where aptamers are used as biochemical receptors. The combined advantages of highly sensitive whispering gallery mode resonator (WGMR)-based transducers, and of the unique properties of aptamers make this approach extremely interesting in the medical field, where there is a particularly high need for devices able to provide real time diagnosis for cancer, infectious diseases, or strokes. However, despite the superior performances of aptamers compared to antibodies and WGMR to other evanescent sensors, there is not much literature combining both types of receptors and transducers. Up to now, the WGMR that have been used are silica microspheres and silicon oxynitride (SiON) ring resonators.

  7. Aptasensors Based on Whispering Gallery Mode Resonators

    PubMed Central

    Nunzi Conti, Gualtiero; Berneschi, Simome; Soria, Silvia

    2016-01-01

    In this paper, we review the literature on optical evanescent field sensing in resonant cavities where aptamers are used as biochemical receptors. The combined advantages of highly sensitive whispering gallery mode resonator (WGMR)-based transducers, and of the unique properties of aptamers make this approach extremely interesting in the medical field, where there is a particularly high need for devices able to provide real time diagnosis for cancer, infectious diseases, or strokes. However, despite the superior performances of aptamers compared to antibodies and WGMR to other evanescent sensors, there is not much literature combining both types of receptors and transducers. Up to now, the WGMR that have been used are silica microspheres and silicon oxynitride (SiON) ring resonators. PMID:27438861

  8. Chemical Sensors Based on Optical Ring Resonators

    NASA Technical Reports Server (NTRS)

    Homer, Margie; Manfreda, Allison; Mansour, Kamjou; Lin, Ying; Ksendzov, Alexander

    2005-01-01

    Chemical sensors based on optical ring resonators are undergoing development. A ring resonator according to this concept is a closed-circuit dielectric optical waveguide. The outermost layer of this waveguide, analogous to the optical cladding layer on an optical fiber, is a made of a polymer that (1) has an index of refraction lower than that of the waveguide core and (2) absorbs chemicals from the surrounding air. The index of refraction of the polymer changes with the concentration of absorbed chemical( s). The resonator is designed to operate with relatively strong evanescent-wave coupling between the outer polymer layer and the electromagnetic field propagating along the waveguide core. By virtue of this coupling, the chemically induced change in index of refraction of the polymer causes a measurable shift in the resonance peaks of the ring. In a prototype that has been used to demonstrate the feasibility of this sensor concept, the ring resonator is a dielectric optical waveguide laid out along a closed path resembling a racetrack (see Figure 1). The prototype was fabricated on a silicon substrate by use of standard techniques of thermal oxidation, chemical vapor deposition, photolithography, etching, and spin coating. The prototype resonator waveguide features an inner cladding of SiO2, a core of SixNy, and a chemical-sensing outer cladding of ethyl cellulose. In addition to the ring Chemical sensors based on optical ring resonators are undergoing development. A ring resonator according to this concept is a closed-circuit dielectric optical waveguide. The outermost layer of this waveguide, analogous to the optical cladding layer on an optical fiber, is a made of a polymer that (1) has an index of refraction lower than that of the waveguide core and (2) absorbs chemicals from the surrounding air. The index of refraction of the polymer changes with the concentration of absorbed chemical( s). The resonator is designed to operate with relatively strong

  9. Copper oxide assisted cysteine hierarchical structures for immunosensor application

    NASA Astrophysics Data System (ADS)

    Pandey, Chandra Mouli; Sumana, Gajjala; Tiwari, Ida

    2014-09-01

    The present work describes the promising electrochemical immunosensing strategy based on copper (II) assisted hierarchical cysteine structures (CuCys) varying from star to flower like morphology. The CuCys having average size of 10 μm have been synthesised using L-Cysteine as initial precursor in presence of copper oxide under environmentally friendly conditions in aqueous medium. To delineate the synthesis mechanism, detailed structural investigations have been carried out using characterization techniques such as X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The electrochemical behaviour of self-assembled CuCys on gold electrode shows surface controlled electrode reaction with an apparent electron transfer rate constant of 3.38 × 10-4 cm s-1. This innovative platform has been utilized to fabricate an immunosensor by covalently immobilizing monoclonal antibodies specific for Escherichia coli O157:H7 (E. coli). Under the optimal conditions, the fabricated immunosensor is found to be sensitive and specific for the detection of E. coli with a detection limit of 10 cfu/ml.

  10. Label-free disposable immunosensor for detection of atrazine.

    PubMed

    Belkhamssa, Najet; Justino, Celine I L; Santos, Patrícia S M; Cardoso, Susana; Lopes, Isabel; Duarte, Armando C; Rocha-Santos, Teresa; Ksibi, Mohamed

    2016-01-01

    This work reports the construction of a fast, disposable, and label-free immunosensor for the determination of atrazine. The immunosensor is based on a field effect transistor (FET) where a network of single-walled carbon nanotubes (SWCNTs) acts as the conductor channel, constituting carbon nanotubes field effect transistors (CNTFETs). Anti-atrazine antibodies were adsorbed onto the SWCNTs and subsequently the SWCNTs were protected with Tween 20 to prevent the non-specific binding of bacteria or proteins. The principle of the immunoreaction consists in the direct adsorption of atrazine specific antibodies (anti-atrazine) to SWCNTs networks. After exposed to increasing concentrations of atrazine, the CNTFETs could be used as useful label-free platforms to detect atrazine. Under the optimal conditions, a limit of detection as low as 0.001 ng mL(-1) was obtained, which is lower than that of other methods for the atrazine detection, and in a working range between 0.001 and 10 ng mL(-1). The average recoveries obtained for real water samples spiked with atrazine varied from 87.3% to 108.0%. The results show that the constructed sensors display a high sensitivity and could be useful tools for detecting pesticides like atrazine at low concentrations. They could be also applied to the determination of atrazine in environmental aqueous samples, such as seawater and riverine water. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Flow-through fluorescence immunosensor for atrazine determination.

    PubMed

    Turiel, E; Fernández, P; Pérez-Conde, C; Gutiérrez, A M; Cámara, C

    1998-12-01

    A new flow-through fluoroimmunosensor for atrazine determination based on the use of protein A immobilized on controlled pore glass as immunoreactor is reported. The support, placed in the optical path of the flow cell, allows the 'in situ' quantification of atrazine by on-line antigen-antibody binding upon successive injections of both substances. The immunosensor has a detection limit of 2.1 mug l(-1), a sample speed of about 10 samples per hour, and provides high reproducibility both within-day (3.2% for 5 mug l(-1) and 2.2% for 30 mug l(-1)) and between days. The optimum working concentration range was 2.1-50 mug l(-1). Possible interferences of other triazines like simazine, desethylatrazine (DEA) and desisopropylatrazine (DIA) were evaluated. Simazine and DIA were not cross-reactive; however, the cross-reactivity for DEA was CR=7.7%. The proposed immunosensor was successfully applied to the determination of atrazine in drinking water and citrus fruits.

  12. Copper oxide assisted cysteine hierarchical structures for immunosensor application

    SciTech Connect

    Pandey, Chandra Mouli; Sumana, Gajjala; Tiwari, Ida

    2014-09-08

    The present work describes the promising electrochemical immunosensing strategy based on copper (II) assisted hierarchical cysteine structures (CuCys) varying from star to flower like morphology. The CuCys having average size of 10 μm have been synthesised using L-Cysteine as initial precursor in presence of copper oxide under environmentally friendly conditions in aqueous medium. To delineate the synthesis mechanism, detailed structural investigations have been carried out using characterization techniques such as X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The electrochemical behaviour of self-assembled CuCys on gold electrode shows surface controlled electrode reaction with an apparent electron transfer rate constant of 3.38 × 10{sup −4 }cm s{sup −1}. This innovative platform has been utilized to fabricate an immunosensor by covalently immobilizing monoclonal antibodies specific for Escherichia coli O157:H7 (E. coli). Under the optimal conditions, the fabricated immunosensor is found to be sensitive and specific for the detection of E. coli with a detection limit of 10 cfu/ml.

  13. Copper-doped titanium dioxide nanoparticles as dual-functional labels for fabrication of electrochemical immunosensors.

    PubMed

    Zhang, Sen; Ma, Hongmin; Yan, Liangguo; Cao, Wei; Yan, Tao; Wei, Qin; Du, Bin

    2014-09-15

    Constructions of versatile electroactive labels are key issues in the development of electrochemical immunosensors. In this study, copper-doped titanium dioxide nanoparticle (Cu@TiO2) was synthesized and used as labels for fabrication of sandwich-type electrochemical immunosensors on glassy carbon electrode (GCE). Due to the presence of copper ions, Cu@TiO2 shows a strong response current when coupled to an electrode. The prepared nanocomposite also shows high electrocatalytic activity towards reduction of hydrogen peroxide (H2O2). The dual functionality of Cu@TiO2 enables the fabrication of immunosensor using different detection modes, that is, square wave voltammetry (SWV) or chronoamperometry (CA). While Cu@TiO2 was used as labels of secondary antibodies (Ab2), carboxyl functionalized graphene oxide (CFGO) was used as electrode materials to immobilize primary antibodies (Ab1). Using human immunoglobulin G (IgG) as a model analyte, the immunosensor shows high sensitivity, acceptable stability and good reproducibility for both detection modes. Under optimal conditions, a linear range from 0.1 pg/mL to 100 ng/mL with a detection limit of 0.052 pg/mL was obtained for SWV analysis. For CA analysis, a wider linear range from 0.01 pg/mL to 100 ng/mL and a lower detection limit of 0.0043 pg/mL were obtained. The proposed metal ion-based enzyme-free and noble metal-free immunosensor may have promising applications in clinical diagnoses and many other fields.

  14. Protein Sensors Based on Optical Ring Resonators

    NASA Technical Reports Server (NTRS)

    Lin, Ying; Ksendzov, Alexander

    2006-01-01

    Prototype transducers based on integrated optical ring resonators have been demonstrated to be useful for detecting the protein avidin in extremely dilute solutions. In an experiment, one of the transducers proved to be capable of indicating the presence of avidin at a concentration of as little as 300 pM in a buffer solution a detection sensitivity comparable to that achievable by previously reported protein-detection techniques. These transducers are serving as models for the further development of integrated-optics sensors for detecting small quantities of other proteins and protein-like substances. The basic principle of these transducers was described in Chemical Sensors Based on Optical Ring Resonators (NPO-40601), NASA Tech Briefs, Vol. 29, No. 10 (October 2005), page 32. The differences between the present transducers and the ones described in the cited prior article lie in details of implementation of the basic principle. As before, the resonator in a transducer of the present type is a closed-circuit dielectric optical waveguide. The outermost layer of this waveguide, analogous to the optical cladding layer on an optical fiber, consists of a layer comprising sublayers having indices of refraction lower than that of the waveguide core. The outermost sublayer absorbs the chemical of interest (in this case, avidin). The index of refraction of the outermost sublayer changes with the concentration of absorbed avidin. The resonator is designed to operate with relatively strong evanescent-wave coupling between the outer sublayer and the electromagnetic field propagating along the waveguide core. By virtue of this coupling, the chemically induced change in the index of refraction of the outermost sublayer causes a measurable change in the spectrum of the resonator output.

  15. A highly sensitive immunosensor based on ITO thin films covered by a new semi-conductive conjugated polymer for the determination of TNFα in human saliva and serum samples.

    PubMed

    Aydın, Elif Burcu; Aydın, Muhammet; Sezgintürk, Mustafa Kemal

    2017-11-15

    A novel, ultrasensitive impedimetric immunosensor was constructed for the detection of tumor necrosis factor α (TNFα) by using Poly(3-thiophene acetic acid) (P3), a conjugated polymer as an immobilization matrix. The polymer P3 contains a lot of carboxylic acid groups on its surface that provide a larger biorecognition surface. This developed immunosensor was prepared on hydroxy-bearing ITO surface via an ester bond linkage of polymer P3 to immobilize anti-TNF α antibodies. The ITO electrode modification steps and interaction between anti-TNF α antibody and TNF α antigen were monitored by cyclic voltammetry (CV) and by electrochemical impedance spectroscopy (EIS) method. After the analytical parameters optimization, a linear detection response from 0.01pg/mL to 2pg/mL, a limit of detection LOD of 3.7 fg/mL and a limit of quantification (LOQ) of 12.4 fg/mL were achieved, which provided accurate results (relative standard deviation; 4.03%). The characterization of this developed immunosensor was performed by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), SEM-energy dispersive X-ray (EDX) mapping and atomic force microscopy (AFM). The immunosensor allowed a simple and fast detection of TNF α antigen in human serum and satisfied recoveries (98.69-105.20%) were obtained by using standard addition method. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. A novel sandwich-type electrochemical immunosensor for PSA detection based on PtCu bimetallic hybrid (2D/2D) rGO/g-C3N4.

    PubMed

    Feng, Jinhui; Li, Yueyun; Li, Mingdang; Li, Faying; Han, Jian; Dong, Yunhui; Chen, Zhiwei; Wang, Ping; Liu, Hui; Wei, Qin

    2017-05-15

    In this work, a sensitive sandwich-type electrochemical immunosensor was designed for the quantitative detection of prostate-specific antigen (PSA) by amperometric i-t. The Au loaded on thionine functionalized graphene oxide (Au@Th/GO) was used as a platform to immobilize primary antibodies (Ab1) and accelerate the electron transfer on the electrode interface. PtCu bimetallic hybrid were loaded on 2D/2D reduced graphene oxide/graphitic carbon nitride (PtCu@rGO/g-C3N4) with large surface area and biocompatibility, which were employed as labels for combining secondary antibodies (Ab2) and amplifying signals to improve the sensitivity of the designed immunosensor which attributes to its good activity for the reduction of hydrogen peroxide (H2O2). Under optimal conditions, the designed immunosensor exhibited a linear concentration range from 50fg/mL to 40ng/mL, with a low detection limit of 16.6fg/mL (S/N=3) for PSA. Additionally, the designed immunosensor showed acceptable selectivity, reproducibility and stability. The satisfactory results in analyze human serum samples indicated potential application promising in clinical monitoring of tumor markers.

  17. Electrochemical characterization of an immunosensor for Salmonella spp. detection

    USDA-ARS?s Scientific Manuscript database

    Immunosensors represent a rapid alternative method for diagnosing Salmonella contamination. The objective of this study was to develop and evaluate the performance of an electrochemical immunosensor for the detection of Salmonella spp., the most common foodborne pathogen worldwide. In the immunosens...

  18. Hip Prosthesis Detection based on Complex Natural Resonances.

    PubMed

    Lui, Hoi-Shun; Shuley, Nicholas; Crozier, Stuart

    2005-01-01

    Resonance based radar target detection has been applied to Ground Penetrating Radar (GPR) applications for the detection and recognition of landmines. Target detection is achieved by searching for certain target dependent Complex Natural Resonances (CNRs), which could be considered as a feature set for identification. In this paper, detection of a hip prosthesis under human tissues using resonance based target detection technique is investigated.

  19. [The fabrication of hepatitis B electrochemical immunosensor array].

    PubMed

    Dai, Xiaofeng; Liu, Zhongming

    2008-04-01

    Based on integrate circuit (IC) technology, an eight-channel gold electrodes (GEs) array was developed. The immunosensor array is prepared by co-immobilizing thionine and Hepatitis B (HB) antibody on the gold electrodes through covalently binding them to GEs with a cysteamine/glutaraldehyde linkage. Hepatitis B surface antigen (HBsAg) was detected qualitatively and quantitatively by the peak current decrease percentage of the thionine. HBsAg positive/negative standard serum was well defined by the array. 8-channel synchronous detection for HBsAg was noted to be of good accuracy and reliability. The results of its clinical application were in good agreement with the results from ELISA.

  20. Immunosensor development for rice tungro bacilliform virus (RTBV) detection using antibody nano-gold conjugate

    NASA Astrophysics Data System (ADS)

    Uda, M. N. A.; Hasfalina, C. M.; Samsuzana, A. A.; Hashim, U.; Ariffin, Shahrul A. B.; Zamri, I.; Nur Sabrina, W.; B. Siti Noraini, B.; Faridah, S.; Mazidah, M.; Gopinath, Subash C. B.

    2017-03-01

    Rice tungro disease (RTD) causes major losses to rice crop plantation. Hence, a highly sensitive tools need to be developed for the detection of RTD which can be employed in both laboratory and field. An electrochemical immunosensor system for the detection of RTD, based on immobilized specific antibodies conjugated with gold nanoparticle was developed for this purpose. However, this paper focus for RTBV interaction using the conjugated antibodies which is added with polymer and deposited on carbon screen printed working electrodes.

  1. Highly selective and sensitive detection of β-agonists using a surface plasmon resonance sensor based on an alkanethiol monolayer functionalized on a Au surface.

    PubMed

    Suherman; Morita, Kinichi; Kawaguchi, Toshikazu

    2015-05-15

    Immunosensor surfaces for surface plasmon resonance (SPR) have been constructed using a functionalized succinimidyl propanethiol monolayer as a linker to immobilize β-agonist protein conjugates on a Au surface. Because β-agonist is a small molecule, an indirect competitive inhibition immunoassay was used for detection. The lowest detection limits for ractopamine and salbutamol were 10 ppt (10 pg mL(-1)) and 5 ppt (5 pg mL(-1)), respectively. The fabricated immunosensor surface can be used again for detection after regeneration in 0.1 M sodium hydroxide. It was found that the same sensor surface could be reused for performing over 100 rapid immunoreactions. Moreover, one immunosensing-regeneration cycle requires only 600 s. The fabricated immunosensor surfaces were characterized using SPR and scanning tunneling microscopy observation. In the kinetic study of the indirect competitive immunosensing inhibition, the affinity constant (K1) of salbutamol antibody was smaller than the K1 of ractopamine antibody. Compared to a previous study of clenbuterol detection, it was concluded that the high K1 was coupled with low sensitivity. In the selectivity study, both immunosensor surfaces provided >90% of confidence level for the specific detection of β-agonist compounds. The fabrication of highly selective and sensitive sensor surfaces for detecting β-agonist compounds was confirmed. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Resonant transition-based quantum computation

    NASA Astrophysics Data System (ADS)

    Chiang, Chen-Fu; Hsieh, Chang-Yu

    2017-05-01

    In this article we assess a novel quantum computation paradigm based on the resonant transition (RT) phenomenon commonly associated with atomic and molecular systems. We thoroughly analyze the intimate connections between the RT-based quantum computation and the well-established adiabatic quantum computation (AQC). Both quantum computing frameworks encode solutions to computational problems in the spectral properties of a Hamiltonian and rely on the quantum dynamics to obtain the desired output state. We discuss how one can adapt any adiabatic quantum algorithm to a corresponding RT version and the two approaches are limited by different aspects of Hamiltonians' spectra. The RT approach provides a compelling alternative to the AQC under various circumstances. To better illustrate the usefulness of the novel framework, we analyze the time complexity of an algorithm for 3-SAT problems and discuss straightforward methods to fine tune its efficiency.

  3. A parity checker circuit based on microelectromechanical resonator logic elements

    NASA Astrophysics Data System (ADS)

    Hafiz, Md Abdullah Al; Li, Ren; Younis, Mohammad I.; Fariborzi, Hossein

    2017-03-01

    Micro/nano-electromechanical resonator based logic computation has attracted significant attention in recent years due to its dynamic mode of operation, ultra-low power consumption, and potential for reprogrammable and reversible computing. Here we demonstrate a 4-bit parity checker circuit by utilizing recently developed logic gates based on MEMS resonators. Toward this, resonance frequencies of shallow arch shaped micro-resonators are electrothermally tuned by the logic inputs to constitute the required logic gates for the proposed parity checker circuit. This study demonstrates that by utilizing MEMS resonator based logic elements, complex digital circuits can be realized.

  4. An ultrasensitive sandwich-type electrochemical immunosensor based on the signal amplification strategy of echinoidea-shaped Au@Ag-Cu2O nanoparticles for prostate specific antigen detection.

    PubMed

    Yang, Yuying; Yan, Qin; Liu, Qing; Li, Yongpeng; Liu, Hui; Wang, Ping; Chen, Lei; Zhang, Daopeng; Li, Yueyun; Dong, Yunhui

    2018-01-15

    Highly sensitive determination of tumor markers plays an important role in early diagnosis of cancer. Herein, a novel and ultrasensitive sandwich-type electrochemical immunosensor was fabricated for quantitative detection of prostate specific antigen (PSA). In this process, gold nanoparticles functionalized nitrogen-doped graphene quantum dots (Au@N-GQDs) was synthesized through a simple and green hydrothermal procedure to enhance conductivity, specific electrode surface area and quantity of immobilized primary antibodies (Ab1). Subsequently, the prepared echinoidea-shaped nanocomposites (Au@Ag-Cu2O) composed of Au@Ag core-shell nanoparticles and disordered cuprous oxide were prepared successfully to label the secondary antibodies (Ab2), which convened the advantages of good biocompatibility and high specific surface area. Because of the synergetic effect present in Au, Ag and Cu2O, the novel nanocomposites exhibited excellent electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2) for the amplified detection of PSA. Therefore, the as-proposed immunosensor for the detection of PSA possessed wide dynamic range from 0.01pg/mL to 100ng/mL with a low detection limit of 0.003pg/mL (S/N = 3). Furthermore, this sandwich-type immunosensor revealed high sensitivity, high selectivity and long-term stability, which had promising application in bioassay analysis. Copyright © 2017. Published by Elsevier B.V.

  5. ZnO thin film transistor immunosensor with high sensitivity and selectivity

    NASA Astrophysics Data System (ADS)

    Reyes, Pavel Ivanoff; Ku, Chieh-Jen; Duan, Ziqing; Lu, Yicheng; Solanki, Aniruddh; Lee, Ki-Bum

    2011-04-01

    A zinc oxide thin film transistor-based immunosensor (ZnO-bioTFT) is presented. The back-gate TFT has an on-off ratio of 108 and a threshold voltage of 4.25 V. The ZnO channel surface is biofunctionalized with primary monoclonal antibodies that selectively bind with epidermal growth factor receptor (EGFR). Detection of the antibody-antigen reaction is achieved through channel carrier modulation via pseudo double-gating field effect caused by the biochemical reaction. The sensitivity of 10 fM detection of pure EGFR proteins is achieved. The ZnO-bioTFT immunosensor also enables selectively detecting 10 fM of EGFR in a 5 mg/ml goat serum solution containing various other proteins.

  6. Resonance Parameter Adjustment Based on Integral Experiments

    SciTech Connect

    Sobes, Vladimir; Leal, Luiz; Arbanas, Goran; Forget, Benoit

    2016-06-02

    Our project seeks to allow coupling of differential and integral data evaluation in a continuous-energy framework and to use the generalized linear least-squares (GLLS) methodology in the TSURFER module of the SCALE code package to update the parameters of a resolved resonance region evaluation. We recognize that the GLLS methodology in TSURFER is identical to the mathematical description of a Bayesian update in SAMMY, the SAMINT code was created to use the mathematical machinery of SAMMY to update resolved resonance parameters based on integral data. Traditionally, SAMMY used differential experimental data to adjust nuclear data parameters. Integral experimental data, such as in the International Criticality Safety Benchmark Experiments Project, remain a tool for validation of completed nuclear data evaluations. SAMINT extracts information from integral benchmarks to aid the nuclear data evaluation process. Later, integral data can be used to resolve any remaining ambiguity between differential data sets, highlight troublesome energy regions, determine key nuclear data parameters for integral benchmark calculations, and improve the nuclear data covariance matrix evaluation. Moreover, SAMINT is not intended to bias nuclear data toward specific integral experiments but should be used to supplement the evaluation of differential experimental data. Using GLLS ensures proper weight is given to the differential data.

  7. Resonance Parameter Adjustment Based on Integral Experiments

    DOE PAGES

    Sobes, Vladimir; Leal, Luiz; Arbanas, Goran; ...

    2016-06-02

    Our project seeks to allow coupling of differential and integral data evaluation in a continuous-energy framework and to use the generalized linear least-squares (GLLS) methodology in the TSURFER module of the SCALE code package to update the parameters of a resolved resonance region evaluation. We recognize that the GLLS methodology in TSURFER is identical to the mathematical description of a Bayesian update in SAMMY, the SAMINT code was created to use the mathematical machinery of SAMMY to update resolved resonance parameters based on integral data. Traditionally, SAMMY used differential experimental data to adjust nuclear data parameters. Integral experimental data, suchmore » as in the International Criticality Safety Benchmark Experiments Project, remain a tool for validation of completed nuclear data evaluations. SAMINT extracts information from integral benchmarks to aid the nuclear data evaluation process. Later, integral data can be used to resolve any remaining ambiguity between differential data sets, highlight troublesome energy regions, determine key nuclear data parameters for integral benchmark calculations, and improve the nuclear data covariance matrix evaluation. Moreover, SAMINT is not intended to bias nuclear data toward specific integral experiments but should be used to supplement the evaluation of differential experimental data. Using GLLS ensures proper weight is given to the differential data.« less

  8. Resonance Parameter Adjustment Based on Integral Experiments

    SciTech Connect

    Sobes, Vladimir; Leal, Luiz; Arbanas, Goran; Forget, Benoit

    2016-06-02

    Our project seeks to allow coupling of differential and integral data evaluation in a continuous-energy framework and to use the generalized linear least-squares (GLLS) methodology in the TSURFER module of the SCALE code package to update the parameters of a resolved resonance region evaluation. We recognize that the GLLS methodology in TSURFER is identical to the mathematical description of a Bayesian update in SAMMY, the SAMINT code was created to use the mathematical machinery of SAMMY to update resolved resonance parameters based on integral data. Traditionally, SAMMY used differential experimental data to adjust nuclear data parameters. Integral experimental data, such as in the International Criticality Safety Benchmark Experiments Project, remain a tool for validation of completed nuclear data evaluations. SAMINT extracts information from integral benchmarks to aid the nuclear data evaluation process. Later, integral data can be used to resolve any remaining ambiguity between differential data sets, highlight troublesome energy regions, determine key nuclear data parameters for integral benchmark calculations, and improve the nuclear data covariance matrix evaluation. Moreover, SAMINT is not intended to bias nuclear data toward specific integral experiments but should be used to supplement the evaluation of differential experimental data. Using GLLS ensures proper weight is given to the differential data.

  9. Nanomaterial Labels in Electrochemical Immunosensors and Immunoassays

    SciTech Connect

    Liu, Guodong; Lin, Yuehe

    2007-12-15

    This article reviews recent advances in nanomaterial labels in electrochemical immunosensors and immunoassays. Various nanomaterial labels are discussed, including colloidal gold/silver, semiconductor nanoparticles, and markers loaded nanocarriers (carbon nanotubes, apoferritin, silica nanoparticles, and liposome beads). The enormous signal enhancement associated with the use of nanomaterial labels and with the formation of nanomaterial–antibody-antigen assemblies provides the basis for ultrasensitive electrochemical detection of disease-related protein biomarkers, biothreat agents, or infectious agents. In general, all endeavors cited here are geared to achieve one or more of the following goals: signal amplification by several orders of magnitude, lower detection limits, and detecting multiple targets.

  10. Nanomaterial Labels in Electrochemical Immunosensors and Immunoassays

    PubMed Central

    Liu, Guodong; Lin, Yuehe

    2009-01-01

    This article reviews recent advances in nanomaterial labels in electrochemical immunosensors and immunoassays. Various nanomaterial labels are discussed, including colloidal gold/silver, semiconductor nanoparticles, and markers loaded nanocarriers (carbon nanotubes, apoferritin, silica nanoparticles, and liposome beads). The enormous signal enhancement associated with the use of nanomaterial labels and with the formation of nanomaterial–antibody-antigen assemblies provides the basis for ultrasensitive electrochemical detection of disease-related protein biomarkers, biothreat agents, or infectious agents. In general, all endeavors cited here are geared to achieve one or more of the following goals: signal amplification by several orders of magnitude, lower detection limits, and detecting multiple targets. PMID:18371644

  11. Bacteria-modified amperometric immunosensor for a Brucella melitensis antibody assay.

    PubMed

    Li, Zhi-Zhang; Gong, Fu-Chun; Shen, Guo-Li; Yu, Ru-Qin

    2002-06-01

    A novel amperometric immunosensor setup is described which uses horseradish peroxidase (HRP) as a label in conjunction with a current-based Brucella sensor. The Bacteria modified immunosensor was constructed by using a biocomposite formed by dispersing graphite powder into a mixture of Brucella melitensis and silicate polymer gel. The enzyme-labeled antibody can readily diffuse toward the encapsulated antigen (Brucella melitensis), which retains its binding properties, and the association reaction is easily detected at the surface exposed to the solution. The use of an oaminophenol (o-AP) substrate and amperometric detection at -150 mV (vs. SCE) results in a relatively low detection limit of 3.5 ng/ml and a linear detection range of 3.5 ng/ml to 200 ng/ml. Based on an optimized parameter, the prepared sensor was used to detect the Brucella melitensis antibody in serum samples by using a competitive binding assay. The results demonstrate the feasibility of employing the proposed immunosensor for the detection for Brucella melitensis antibody in a clinical analysis.

  12. Optical immunosensors for detection of Listeria monocytogenes and Salmonella enteritidis from food

    NASA Astrophysics Data System (ADS)

    Bhunia, Arun K.; Geng, Tao; Lathrop, Amanda; Valadez, Angela; Morgan, Mark T.

    2004-03-01

    Listeria monocytogenes and Salmonella are two major foodborne pathogens of significant concern. Two optical evanescent wave immunosensors were evaluated for detection: Antibody-coupled fiber-optic biosensor and a surface plasmon resonant (SPR) immunosensor. In the fiber-optic sensor, polyclonal antibodies for the test organisms were immobilized on polystyrene fiber wave -guides using streptavidin - biotin chemistry. Cyanine 5 -labeled monoclonal antibodies C11E9 (for L. monocytogenes) and SF-11 (for Salmonella Enteritidis) were used to generate a specific fluorescent signal. Signal acquisition was performed by launching a laser-light (635 nm) from an Analyte-2000. This immunosensor was able to detect 103 - 109 cfu/ml of L. monocytogenes or 106-109 cfu/ml of Salmonella Enteritidis and the assays were conducted at near real-time with results obtained within one hour of sampling. The assays were specific and showed signal even in the presence of other microorganisms such as E. coli, Enterococcus faecalis or Salmonella Typhimurium. In the SPR system, IAsys instrument (resonant mirror sensor) was used. Monoclonal antibody-C11E9 was directly immobilized onto a carboxylate cuvette. Whole Listeria cells at various concentrations did not yield any signal while surface protein extracts did. Crude protein extracts from L. monocytogenes and L. innocua had average binding responses of around 150 arc sec (0.25 ng/mm2), which was significantly different from L. grayi, L. ivanovii, or L. welshimeri with average responses of <48 arc sec. Both fiber-optic and SPR sensors show promise in near real-time detection of foodborne L. monocytogenes and Salmonella Enteritidis.

  13. Advances in resonance based NDT for ceramic components

    NASA Astrophysics Data System (ADS)

    Hunter, L. J.; Jauriqui, L. M.; Gatewood, G. D.; Sisneros, R.

    2012-05-01

    The application of resonance based non-destructive testing methods has been providing benefit to manufacturers of metal components in the automotive and aerospace industries for many years. Recent developments in resonance based technologies are now allowing the application of resonance NDT to ceramic components including turbine engine components, armor, and hybrid bearing rolling elements. Application of higher frequencies and advanced signal interpretation are now allowing Process Compensated Resonance Testing to detect both internal material defects and surface breaking cracks in a variety of ceramic components. Resonance techniques can also be applied to determine material properties of coupons and to evaluate process capability for new manufacturing methods.

  14. Signal enhancement strategy for a micro-arrayed polydiacetylene (PDA) immunosensor using enzyme-catalyzed precipitation.

    PubMed

    Lee, Jong Uk; Jeong, Ji Hoon; Lee, Doo Sung; Sim, Sang Jun

    2014-11-15

    This paper describes a signal enhancement strategy to improve the sensitivity of an antibody-based immunosensor that uses polydiacetylene (PDA) liposomes to detect a target protein (human immunoglobulin E [hIgE]). To achieve ultrasensitive detection, multiple stimuli applied to PDA immunosensor chips offer a signal enhancement method that combines the primary immune reaction between antigen and antibody with the sandwich method of polyclonal antibody (pAb)-conjugated horseradish peroxidase (HRP). In the second step, fluorescence is enhanced by the mechanical pressure from the precipitate formed by enzyme catalysis. In order to detect hIgE, the surface of immobilized PDA liposomes was conjugated with monoclonal antibodies against hIgE, and fluorescence signals were detected after the antigen-antibody reaction. In this step, hIgE concentrations as low as 10 ng/mL were detected. Fluorescence signals slightly increased when anti-hIgE pAb-HRP was used as an amplifying agent after primary immunoresponse. After secondary immunoresponse, HRP-catalyzed oxidation of 3,3'-diaminobenzidine produced an insoluble precipitate that strongly stimulated PDA liposomes by their weight and pressure, thereby dramatically increasing the fluorescence signal. Thus, PDA liposome immunosensor could detect hIgE concentrations as low as 0.01 ng/mL, representing a 1000-fold increase in sensitivity over the signal generated by the primary immunoresponse. This study indicates that increasing the external mechanical force applied to PDA liposomes by enzyme-catalyzed precipitate formation enhanced the sensitivity of the PDA liposome immunosensor chip. This strategy can be applied to the detection of other biomolecules in experimental or clinical settings where ultrasensitive and highly specific biosensing is required. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Development of a label-free immunosensor system for detecting plasma cortisol levels in fish.

    PubMed

    Wu, Haiyun; Ohnuki, Hitoshi; Hibi, Kyoko; Ren, Huifeng; Endo, Hideaki

    2016-02-01

    Fishes display a wide variation in their physiological responses to stress, which is clearly evident in the plasma corticosteroid changes, chiefly cortisol levels in fish. In the present study, we describe a novel label-free immunosensor for detecting plasma cortisol levels. The method is based on immunologic reactions and amperometric measurement using cyclic voltammetry. For the immobilization of the antibody on the surface of sensing electrode, we used a self-assembled monolayer of thiol-containing compounds. Using this electrode, we detect the CV signal change caused by the generation of antigen-antibody complex. The immunosensor showed a response to cortisol levels, and the anodic peak value linearly decreased with a correlation coefficient of 0.990 in diluted plasma. The specificity of the label-free immunosensor system was investigated using other steroid hormones, such as 17α, 20β-dihydroxy-4-pregnen-3-one, progesterone, estriol, estradiol, and testosterone. The specific detection of cortisol was suggested by a minimal change from -0.32 to 0.51 μA in the anodic peak value of the other steroid hormones. The sensor system was used to determine the plasma cortisol levels in Nile tilapia (Oreochromis niloticus), and the results were compared with those of the same samples determined using the conventional method (ELISA). A good correlation was obtained between values determined using both methods (correlation coefficient 0.993). These findings suggest that the proposed label-free immunosensor could be useful for rapid and convenient analysis of cortisol levels in fish plasma samples.

  16. Comparative study of random and oriented antibody immobilization techniques on the binding capacity of immunosensor.

    PubMed

    Kausaite-Minkstimiene, A; Ramanaviciene, A; Kirlyte, J; Ramanavicius, A

    2010-08-01

    A comparative study of four different antibody immobilization techniques that are suitable for modification of surface plasmon resonance (SPR) chip (SPR-chip) is reported. Antibodies against human growth hormone (anti-HGH) were used as the model system. The evaluated SPR-chip modification techniques were (i) random immobilization of intact anti-HGH (intact-anti-HGH) via self-assembled monolayer (SAM) based on 11-mercaptoundecanoic acid (MUA); (ii) random immobilization of intact-anti-HGH within carboxymethyl dextran (CMD) hydrogel by direct covalent amine coupling technique; (iii) oriented coupling of intact-anti-HGH via Fc-fragment to protein-G layer assembled on SAM consisting of MUA (MUA/pG); (iv) oriented immobilization of fragmented anti-HGH antibodies (frag-anti-HGH) via their native thiol-groups directly coupled to the gold. To liberate these thiol groups, the intact-anti-HGH was chemically "divided" into two frag-anti-HGH fragments by chemical reduction with 2-mercaptoethylamine (2-MEA). Optimal concentration of 2-MEA for preparation of anti-HGH was 15 mM. The surface concentration of immobilized antibodies and the antigen binding capacity for all four differently modified SPR-chips was evaluated and compared. The maximum surface concentration of immobilized intact-anti-HGH was obtained by immobilizing the antibody within CMD-hydrogel. The maximal antigen binding capacity was obtained by SPR-chip based on intact-anti-HGH immobilized via MUA/pG. The immobilization based on application of frag-anti-HGH was found to be the most suitable for design of SPR-immunosensor for HGH detection, due to its sufficient antigen binding capacity, simplicity, and low cost in respect to the currently evaluated techniques.

  17. Temperature dependence of immunoreactions using shear horizontal surface acoustic wave immunosensors

    NASA Astrophysics Data System (ADS)

    Kogai, Takashi; Yatsuda, Hiromi; Kondoh, Jun

    2017-07-01

    In this paper, the temperature dependence of immunoreactions, which are antibody-antigen reactions, on a shear horizontal surface acoustic wave (SH-SAW) immunosensor is described. The immunosensor is based on a reflection-type delay line on a 36° Y-cut 90° X-propagation quartz substrate, where the delay line is composed of a floating electrode unidirectional transducer (FEUDT), a grating reflector, and a sensing area between them. In order to evaluate the temperature dependence of immunoreactions, human serum albumin (HSA) antigen-antibody reactions are investigated. The SH-SAW immunosensor chip is placed in a thermostatic chamber and the changes in the SH-SAW velocity resulting from the immunoreactions are measured at different temperatures. As a result, it is observed that the HSA immunoreactions are influenced by the ambient temperature and that higher temperatures provide more active reactions. In order to analyze the immunoreactions, an analytical approach using an exponential fitting method for changes in SH-SAW velocity is employed.

  18. Analysis of zearalenone in cereal and Swine feed samples using an automated flow-through immunosensor.

    PubMed

    Urraca, Javier L; Benito-Peña, Elena; Pérez-Conde, Concepción; Moreno-Bondi, María C; Pestka, James J

    2005-05-04

    The development of a sensitive flow-though immunosensor for the analysis of the mycotoxin zearalenone in cereal samples is described. The sensor was completely automated and was based on a direct competitive immunosorbent assay and fluorescence detection. The mycotoxin competes with a horseradish-peroxidase-labeled derivative for the binding sites of a rabbit polyclonal antibody. Control pore glass covalently bound to Prot A was used for the oriented immobilization of the antibody-antigen immunocomplexes. The immunosensor shows an IC(50) value of 0.087 ng mL(-1) (RSD = 2.8%, n = 6) and a dynamic range from 0.019 to 0.422 ng mL(-1). The limit of detection (90% of blank signal) of 0.007 ng mL(-1) (RSD = 3.9%, n = 3) is lower than previously published methods. Corn, wheat, and swine feed samples have been analyzed with the device after extraction of the analyte using accelerated solvent extraction (ASE). The immunosensor has been validated using a corn certificate reference material and HPLC with fluorescence detection.

  19. Sub-attomolar detection of cholera toxin using a label-free capacitive immunosensor.

    PubMed

    Loyprasert, S; Hedström, M; Thavarungkul, P; Kanatharana, P; Mattiasson, B

    2010-04-15

    A label-free immunosensor for the direct detection of cholera toxin (CT) at sub-attomolar level has been developed based on potential-step capacitance measurements. Anti-CT antibody was adsorbed on gold nanoparticles (AuNPs) incorporated on a polytyramine-modified gold electrode. The concentration of CT was determined by detecting the change of capacitance caused by the formation of antibody-antigen complexes. By using AuNPs adsorbed to the sensing surface, the signal was dramatically increased leading to a significantly more sensitive assay. In fact, under optimum conditions the immunosensor could detect CT concentration with a limit of detection of 9 x 10(-20)M or 0.09 aM, with a dynamic range between 0.1 aM and 10 pM. Good analytical reproducibility could be obtained by injecting CT up to 36 times with an RSD of 2.5%. In addition, good performance of the developed immunosensor was achieved when applied to turbid water samples collected from a local stream that were spiked with CT.

  20. Detection of Explosives in a Dynamic Marine Environment Using a Moored TNT Immunosensor

    PubMed Central

    Charles, Paul T.; Adams, André A.; Deschamps, Jeffrey R.; Veitch, Scott; Hanson, Al; Kusterbeck, Anne W.

    2014-01-01

    A field demonstration and longevity assessment for long-term monitoring of the explosive 2,4,6-trinitrotoluene (TNT) in a marine environment using an anti-TNT microfluidic immunosensor is described. The TNT immunosensor is comprised of a microfluidic device with 39 parallel microchannels (2.5 cm × 250 μm × 500 μm, L × W × D) fabricated in poly(methylmethacrylate) (PMMA), then chemically functionalized with antibodies possessing a high affinity for TNT. Synthesized fluorescence reporter complexes used in a displacement-based assay format were used for TNT identification. For field deployment the TNT immunosensor was configured onto a submersible moored steel frame along with frame controller, pumps and TNT plume generator and deployed pier side for intermittent plume sampling of TNT (1h increments). Under varying current and tidal conditions trace levels of TNT in natural seawater were detected over an extended period (>18 h). Overnight operation and data recording was monitored via a web interface. PMID:24583970

  1. Pt NPs and DNAzyme functionalized polymer nanospheres as triple signal amplification strategy for highly sensitive electrochemical immunosensor of tumour marker.

    PubMed

    Chang, Honghong; Zhang, Haochun; Lv, Jia; Zhang, Bing; Wei, Wenlong; Guo, Jingang

    2016-12-15

    Highly sensitive determination of tumour markers is the key for early diagnosis of cancer. Herein, triple signal amplification strategy resulting from polymer nanospheres, Pt NPs, and DNAzyme was proposed in the developed electrochemical immunosensor. First, electroactive polymer nanospheres were synthesized by infinite coordination polymerization of ferrocenedicarboxylic acid, which could generate strong electrochemical signals due to plentiful ferrocene molecules. Further, the polymer nanospheres were functionalized by Pt NPs and DNAzyme (hemin/G-quadruplex) with the ability of catalyzing H2O2, which contributes to enhance the electrochemical signals. The prepared conjugations were characterized by transmission electron microscope (TEM) and energy dispersive X-ray spectroscopy (EDX). And the process of preparation was monitored by zeta potential. Based on the sandwich-type immunoassay, the electrochemical immunosensor was constructed employing the conjugations as signal tags. Under optimal conditions, the DPV peak increased with the increasing of alpha fetal protein (AFP) concentration, and the linear range was from 0.1pgmL(-1) to 100ngmL(-1) with low detection limit of 0.086pgmL(-1). Meanwhile, the designed immunosensor exhibited excellent selectivity and anti-interference property, good reproducibility and stability. More importantly, there were no significant differences in analyzing real clinical samples between designed immunosensor and commercial ELISA.

  2. Development of optical immunosensors and their application to the analysis of human bone morphogenetic protein-7 (BMP-7)

    NASA Astrophysics Data System (ADS)

    Kim, Chun-Kwang; Rhee, Jong Il; Sohn, Ok-Jae

    2011-03-01

    In this study, a few optical immunosensors were developed to determine the concentration of BMP-7. Hydrophilic CdSe/ZnS quantum dots (QDs) were synthesized and conjugated to the antibody of BMP-7 (BMP-7Ab). The QDconjugated BMP-7Ab was used as a fluorescence probe at excitation and emission wavelengths of 470 nm and 585 nm, respectively. It was immobilized either on the bottom of the well of a 96-well microtiter plate or on the tip of an optical fiber. Two immunoassays, i.e. the direct and sandwich assays, were studied for their sensitivity. The sensitivity of the direct immunoassay was 1296.21, compared to 384.69 for the sandwich assay. The linear detection range was 0.0-1.0 ng/mL for both assays. Based on the results of the microtiter plate technique, the direct assay technique was used for the development of an optical fiber immunosensor. The optical fiber immunosensor has a linear detection range between 0.0 and 10.0 ng/mL with a detection limit of 0.413 ng/mL. The optical fiber immunosensor was applied to the sequential injection analysis for the automatic determination of BMP-7.

  3. A label-free electrochemical immunosensor for the detection of cardiac marker using graphene quantum dots (GQDs).

    PubMed

    Tuteja, Satish K; Chen, Rui; Kukkar, Manil; Song, Chung Kil; Mutreja, Ruchi; Singh, Suman; Paul, Ashok K; Lee, Haiwon; Kim, Ki-Hyun; Deep, Akash; Suri, C Raman

    2016-12-15

    A label-free immunosensor based on electrochemical impedance spectroscopy has been developed for the sensitive detection of a cardiac biomarker myoglobin (cMyo). Hydrothermally synthesized graphene quantum dots (GQDs) have been used as an immobilized template on screen printed electrodes for the construction of an impedimetric sensor platform. The GQDs-modified electrode was conjugated with highly specific anti-myoglobin antibodies to develop the desired immunosensor. The values of charge transfer resistance (Rct) were monitored as a function of varying antigen concentration. The Rct value of the immunosensor showed a linear increase (from 0.20 to 0.31kΩ) in the range of 0.01-100ng/mL cMyo. The specific detection of cMyo was also made in the presence of other competing proteins. The limit of detection for the proposed immunosensor was estimated as 0.01ng/mL which is comparable to the standard ELISA techniques.

  4. Wireless power transfer based on dielectric resonators with colossal permittivity

    NASA Astrophysics Data System (ADS)

    Song, Mingzhao; Belov, Pavel; Kapitanova, Polina

    2016-11-01

    Magnetic resonant wireless power transfer system based on dielectric disk resonators made of colossal permittivity (ɛ = 1000) and low loss (tan δ = 2.5 × 10-4) microwave ceramic is experimentally investigated. The system operates at the magnetic dipole mode excited in the resonators providing maximal power transfer efficiency of 90% at the frequency 232 MHz. By applying an impedance matching technique, the efficiency of 50% is achieved within the separation between the resonators d = 16 cm (3.8 radii of the resonator). The separation, misalignment and rotation dependencies of wireless power transfer efficiency are experimentally studied.

  5. An electrochemical immunosensor for sensitive detection of Escherichia coli O157:H7 by using chitosan, MWCNT, polypyrrole with gold nanoparticles hybrid sensing platform.

    PubMed

    Güner, Ahmet; Çevik, Emre; Şenel, Mehmet; Alpsoy, Lokman

    2017-08-15

    An electrochemical immunosensor for the common food pathogen Escherichia coli O157:H7 was developed. This novel immunosensor based on the PPy/AuNP/MWCNT/Chi hybrid bionanocomposite modified pencil graphite electrode (PGE). This hybrid bionanocomposite platform was modified with anti-E. coli O157:H7 monoclonal antibody. The prepared bionanocomposite platform and immunosensor was characterized by using cyclic voltammetry (CV). Under the optimum conditions, the results have shown the order of the preferential selectivity of the method is gram negative pathogenic species E. coli O157:H7. Concentrations of E. coli O157:H7 from 3×10(1) to 3×10(7)cfu/mL could be detected. The detection limit was ∼30cfu/mL in PBS buffer. Briefly, we developed a high sensitive electrochemical immunosensor for specific detection of E. coli O157:H7 contamination with the use of sandwich assay evaluated in this study offered a reliable means of quantification of the bacteria. For the applications in food quality and safety control, our immunosensor showed reproducibility and stability. Copyright © 2017. Published by Elsevier Ltd.

  6. An amplified comparative fluorescence resonance energy transfer immunosensing of CA125 tumor marker and ovarian cancer cells using green and economic carbon dots for bio-applications in labeling, imaging and sensing.

    PubMed

    Hamd-Ghadareh, Somayeh; Salimi, Abdollah; Fathi, Fardin; Bahrami, Saman

    2017-10-15

    CA125, is a marker in the clinical diagnosis of several cancers and currently is the best serum-based tumor marker for ovarian cancer. Here, we developed an ultrasensitive antibody-ssDNA aptamer sandwich-type fluorescence immunosensor for CA125 detection. Based on a novel signal amplification strategy the carbon dots (CDs) functionalized with aptamer (CD-aptamer) used as detection probe and PAMAM-Dendrimers/AuNPs was used for covalent attachment of CA125-antibody and completing the sandwich assay method. By measuring of fluorescence resonance energy transfer (FRET) signals between CDs and AuNPs as nanoquenchers, the fluorescence signal quenched during sandwich complex formed between anti-CA125, CA125 and CDs-Aptamer and decreasing of fluorescence response signal is related to CA125 concentrations. Under optimal conditions, the immunosensor exhibited an extremely low calculated detection limit of 0.5fg/mL with wide linear range 1.0fg/mL to 1.0ng/mL of CA 125. The application of the immunosensor for CA125 detection in serum samples and measuring of ovarian-cancer cells was also investigated. The immunosensor revealed good sensitivity and specificity with ovarian cell concentrations from 2.5×10(3) to 2×10(4)cells/mL with correlation coefficient of 0.9937 and detection limit of 400cells/mL (4 cell in 10μL), indicating potential application of immunosensor in clinical monitoring of tumor biomarkers. Furthermore, the cell viability was not changed upon treatment with CDs probe during 24h, showing the low cytotoxicity of the probe. More importantly, CDs-antibody hybrid was achieved in selective imaging of the cancer cells over the OVCAR-3 line cells, implying its potential applications in biosensing, as well as in cancer diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Microwave Oscillators Based on Nonlinear WGM Resonators

    NASA Technical Reports Server (NTRS)

    Maleki, Lute; Matsko, Andrey; Savchenkov, Anatoliy; Strekalov, Dmitry

    2006-01-01

    Optical oscillators that exploit resonantly enhanced four-wave mixing in nonlinear whispering-gallery-mode (WGM) resonators are under investigation for potential utility as low-power, ultra-miniature sources of stable, spectrally pure microwave signals. There are numerous potential uses for such oscillators in radar systems, communication systems, and scientific instrumentation. The resonator in an oscillator of this type is made of a crystalline material that exhibits cubic Kerr nonlinearity, which supports the four-photon parametric process also known as four-wave mixing. The oscillator can be characterized as all-optical in the sense that the entire process of generation of the microwave signal takes place within the WGM resonator. The resonantly enhanced four-wave mixing yields coherent, phase-modulated optical signals at frequencies governed by the resonator structure. The frequency of the phase-modulation signal, which is in the microwave range, equals the difference between the frequencies of the optical signals; hence, this frequency is also governed by the resonator structure. Hence, further, the microwave signal is stable and can be used as a reference signal. The figure schematically depicts the apparatus used in a proof-of-principle experiment. Linearly polarized pump light was generated by an yttrium aluminum garnet laser at a wavelength of 1.32 microns. By use of a 90:10 fiber-optic splitter and optical fibers, some of the laser light was sent into a delay line and some was transmitted to one face of glass coupling prism, that, in turn, coupled the laser light into a crystalline CaF2 WGM disk resonator that had a resonance quality factor (Q) of 6x10(exp 9). The output light of the resonator was collected via another face of the coupling prism and a single-mode optical fiber, which transmitted the light to a 50:50 fiber-optic splitter. One output of this splitter was sent to a slow photodiode to obtain a DC signal for locking the laser to a particular

  8. Accuracy of magnetic resonance based susceptibility measurements

    NASA Astrophysics Data System (ADS)

    Erdevig, Hannah E.; Russek, Stephen E.; Carnicka, Slavka; Stupic, Karl F.; Keenan, Kathryn E.

    2017-05-01

    Magnetic Resonance Imaging (MRI) is increasingly used to map the magnetic susceptibility of tissue to identify cerebral microbleeds associated with traumatic brain injury and pathological iron deposits associated with neurodegenerative diseases such as Parkinson's and Alzheimer's disease. Accurate measurements of susceptibility are important for determining oxygen and iron content in blood vessels and brain tissue for use in noninvasive clinical diagnosis and treatment assessments. Induced magnetic fields with amplitude on the order of 100 nT, can be detected using MRI phase images. The induced field distributions can then be inverted to obtain quantitative susceptibility maps. The focus of this research was to determine the accuracy of MRI-based susceptibility measurements using simple phantom geometries and to compare the susceptibility measurements with magnetometry measurements where SI-traceable standards are available. The susceptibilities of paramagnetic salt solutions in cylindrical containers were measured as a function of orientation relative to the static MRI field. The observed induced fields as a function of orientation of the cylinder were in good agreement with simple models. The MRI susceptibility measurements were compared with SQUID magnetometry using NIST-traceable standards. MRI can accurately measure relative magnetic susceptibilities while SQUID magnetometry measures absolute magnetic susceptibility. Given the accuracy of moment measurements of tissue mimicking samples, and the need to look at small differences in tissue properties, the use of existing NIST standard reference materials to calibrate MRI reference structures is problematic and better reference materials are required.

  9. Correlation of Capture Efficiency with the Geometry, Transport, and Reaction Parameters in Heterogeneous Immunosensors.

    PubMed

    Rath, Dharitri; Panda, Siddhartha

    2016-02-09

    Higher capture efficiency of biomarkers in heterogeneous immunosensors would enable early detection of diseases. Several strategies are used to improve the capture efficiency of these immunosensors including the geometry of the system along with the transport and reaction parameters. Having a prior knowledge of the behavior of the above parameters would facilitate the design of an efficient immunosensor. While the contributions of the transport and reaction parameters toward understanding of the mechanism involved in capture have been well studied in the literature, their effect in combination with the geometry of the sensors has not been explored until now. In this work, we have experimentally demonstrated that the capture efficiency of the antigen-antibody systems is inversely related to the size of the sensor patch. The experimental system was simulated in order to get an in-depth understanding of the mechanism behind the experimental observation. Further, the extent of heterogeneity in the system was analyzed using the Sips isotherm to obtain the heterogeneity index (α) and the reaction rate constant (K(D)) as fitted parameters for a sensor patch of 1.5 mm radius. The experimental kinetic data obtained for the same sensor patch matched reasonably with the simulation results by considering K(D) as the global affinity constant, which indicated that our system can be considered to be homogeneous. Our simulation results associated with the size dependency of the capture efficiency were in agreement with the trends obtained in our experimental observations where an inverse relation was observed owing to the fact that the mass-transfer limitation decreases with the decrease in the size of the sensor patch. The possible underlying mechanism associated with size dependency of capture efficiency was discussed based on the time-dependent radial variation of captured antigens obtained from our simulation results. A study on the parametric variation was further conducted

  10. Electrochemical immunosensor for detection of celiac disease toxic gliadin in foodstuff.

    PubMed

    Nassef, Hossam M; Bermudo Redondo, M Carmen; Ciclitira, Paul J; Ellis, H Julia; Fragoso, Alex; O'Sullivan, Clara K

    2008-12-01

    Celiac disease is a gluten-sensitive enteropathy that affects as much as 1% of the population. Patients with celiac disease should maintain a lifelong gluten-free diet, in order to avoid serious complications and consequences. It is essential to have methods of analysis to reliably control the contents of gluten-free foods, and there is a definitive need for an assay that is easy to use, and can be used on site, to facilitate the rapid testing of incoming raw materials or monitoring for gluten contamination, by industries generating gluten-free foods. Here, we report on the development of an electrochemical immunosensor exploiting an antibody raised against the putative immunodominant celiac disease epitope, for the measurement of gliadin content and potential celiac toxicity of a foodstuff. To develop the gliadin immunosensor, we explored the use of two surface chemistries, based on the use of dithiols, 22-(3,5-bis((6-mercaptohexyl)oxy)phenyl)-3,6,9,12,15,18,21-heptaoxadocosanoic acid (1) and 1,2-dithiolane-3-pentanoic acid (thioctic acid) (2), for anchoring of the capture antibody. The different surface chemistries were evaluated in terms of time required for formation of self-assembled monolayers, stability, susceptibility to nonspecific binding, reproducibility, and sensitivity. The thioctic acid self-assembled monolayer took more than 100 h to attain a stable surface and rapidly destabilized following functionalization with capture antibody, while the heptaoxadocosanoic acid surface rapidlyformed (less than 3 h) and was stable for at least 5 days, stored at room temperature, following antibody immobilization. Both surface chemistries gave rise to highly sensitive immunosensors, with detection limits of 5.5 and 11.6 ng/mL being obtained for 1 and 2, respectively, with nonspecific binding of just 2.7% of the specific signal attained. The immunosensors were extremely reproducible, with RSD of 5.2 and 6.75% obtained for 1 and 2 (n = 5, 30 ng/mL), respectively

  11. Tunable triple Fano resonances based on multimode interference in coupled plasmonic resonator system.

    PubMed

    Li, Shilei; Zhang, Yunyun; Song, Xiaokang; Wang, Yilin; Yu, Li

    2016-07-11

    In this paper, an asymmetric plasmonic structure composed of two MIM (metal-insulator-metal) waveguides and two rectangular cavities is reported, which can support triple Fano resonances originating from three different mechanisms. And the multimode interference coupled mode theory (MICMT) including coupling phases is proposed based on single mode coupled mode theory (CMT), which is used for describing and explaining the multiple Fano resonance phenomenon in coupled plasmonic resonator systems. Just because the triple Fano resonances originate from three different mechanisms, each Fano resonance can be tuned independently or semi-independently by changing the parameters of the two rectangular cavities. Such, a narrow 'M' type of double Lorentzian-like line-shape transmission windows with the position and the full width at half maximum (FWHM) can be tuned freely is constructed by changing the parameters of the two cavities appropriately, which can find widely applications in sensors, nonlinear and slow-light devices.

  12. Fano resonance in a subwavelength Mie-based metamolecule with split ring resonator

    NASA Astrophysics Data System (ADS)

    Wang, Xiaobo; Zhou, Ji

    2017-06-01

    In this letter, we report a method of symmetry-breaking in an artificial Mie-based metamolecule. A Fano resonance with a Q factor of 96 is observed at microwave frequencies in a structure combining a split ring resonator and a high-permittivity dielectric cube. Calculations indicate that resonant frequency tunability will result from the alteration of the cube's permittivity. The asymmetric spectrum is attributed to both constructive and destructive near-field interactions between the two distinct resonators. Experimental data and simulation results are in good agreement. The underlying physics is seen in field distribution and dipole analysis. This work substantiates an approach for the manipulation of Mie resonances which can potentially be utilized in light modulating and sensing.

  13. Immunosensor for the diagnosis of Chagas' disease.

    PubMed

    Ferreira, Antonio Aparecido Pupim; Colli, Walter; da Costa, Paulo Inácio; Yamanaka, Hideko

    2005-07-15

    Trypanosoma cruzi proteins from epimastigote membranes, herein referred as antigens, have been used for the construction of an amperometric immunosensor for serological diagnosis of Chagas' disease. The proteins used had a molecular mass ranging from 30 to 100 kDa. The gold electrode was treated with cysteamine and glutaraldehyde prior to antigen immobilization. Antibodies present in the serum of patients with Chagas' disease were captured by the immobilized antigens and the affinity interaction was monitored by chronoamperometry at a potential of -400 mV (versus Ag pseudo-reference electrode) using peroxidase-labeled IgG conjugate and hydrogen peroxide, iodide substrate. The incubation time to allow maximum antigen-antibody and antibody-peroxidase-labeled IgG interactions was 20 min with a reactivity threshold at -0.104 microA.

  14. Refractive Index Sensor Based on Fano Resonances in Metal-Insulator-Metal Waveguides Coupled with Resonators.

    PubMed

    Tang, Yue; Zhang, Zhidong; Wang, Ruibing; Hai, Zhenyin; Xue, Chenyang; Zhang, Wendong; Yan, Shubin

    2017-04-06

    A surface plasmon polariton refractive index sensor based on Fano resonances in metal-insulator-metal (MIM) waveguides coupled with rectangular and ring resonators is proposed and numerically investigated using a finite element method. Fano resonances are observed in the transmission spectra, which result from the coupling between the narrow-band spectral response in the ring resonator and the broadband spectral response in the rectangular resonator. Results are analyzed using coupled-mode theory based on transmission line theory. The coupled mode theory is employed to explain the Fano resonance effect, and the analytical result is in good agreement with the simulation result. The results show that with an increase in the refractive index of the fill dielectric material in the slot of the system, the Fano resonance peak exhibits a remarkable red shift, and the highest value of sensitivity (S) is 1125 nm/RIU, RIU means refractive index unit. Furthermore, the coupled MIM waveguide structure can be integrated with other photonic devices at the chip scale. The results can provide a guide for future applications of this structure.

  15. Electrically tunable metasurface based on Mie-type dielectric resonators

    NASA Astrophysics Data System (ADS)

    Su, Zhaoxian; Zhao, Qian; Song, Kun; Zhao, Xiaopeng; Yin, Jianbo

    2017-02-01

    In this paper, we have designed a metasurface based on electrically tunable Mie-type resonators and theoretically demonstrated its tunable response to electromagnetic waves with varying frequency. The metasurface consists of disk-like ferroelectric resonators arrayed on a metal film and the upper surface of resonators is covered by ion gel film which is transparent for incident electromagnetic wave. Using the metal film and ion gel film as electrodes, the permittivity of the resonators can be adjusted by an external electric field and, as a result, the reflection phase of the resonators can be dynamically adjusted in a relatively wide range. By programmable controlling the electric field strength applied on resonators of metasurface, a 2π phase ramp can be realized and, thereby, the arbitrary reflection behavior of incident waves with varied frequency is obtained. Because of the tunability, this metasurface can also be used to design adaptive metasurface lens and carpet cloak.

  16. Analysis of an integrated optic micro racetrack resonator based biosensor

    NASA Astrophysics Data System (ADS)

    Malathi, S.; Hegde, Gopalkrishna; Srinivas, T.; Roy, Ugra M.

    2014-06-01

    Silicon-On- Insulator (SOI) technology has huge potential in fabricating compact devices for various applications such as integrated optic waveguides, directional couplers, resonators etc. In this work, we present the analysis of a biosensor based on an integrated optic racetrack resonator, interrogated by a bus waveguide. The biomaterial is applied as a cladding layer. Here we analyze the coupling between the resonator and the bus waveguide, and its dependence on the bio layer. In traditional analysis, the effective refractive index and resonator total path length are the factors influencing the resonant wavelength. Our analysis shows that all parametric values decrease with increase in waveguide width and spacing. The inclusion of waveguide mode overlap and perturbation in coupled mode equation results in enhanced resonator sensitivity of an order of magnitude

  17. Electrically tunable metasurface based on Mie-type dielectric resonators.

    PubMed

    Su, Zhaoxian; Zhao, Qian; Song, Kun; Zhao, Xiaopeng; Yin, Jianbo

    2017-02-21

    In this paper, we have designed a metasurface based on electrically tunable Mie-type resonators and theoretically demonstrated its tunable response to electromagnetic waves with varying frequency. The metasurface consists of disk-like ferroelectric resonators arrayed on a metal film and the upper surface of resonators is covered by ion gel film which is transparent for incident electromagnetic wave. Using the metal film and ion gel film as electrodes, the permittivity of the resonators can be adjusted by an external electric field and, as a result, the reflection phase of the resonators can be dynamically adjusted in a relatively wide range. By programmable controlling the electric field strength applied on resonators of metasurface, a 2π phase ramp can be realized and, thereby, the arbitrary reflection behavior of incident waves with varied frequency is obtained. Because of the tunability, this metasurface can also be used to design adaptive metasurface lens and carpet cloak.

  18. Electrically tunable metasurface based on Mie-type dielectric resonators

    PubMed Central

    Su, Zhaoxian; Zhao, Qian; Song, Kun; Zhao, Xiaopeng; Yin, Jianbo

    2017-01-01

    In this paper, we have designed a metasurface based on electrically tunable Mie-type resonators and theoretically demonstrated its tunable response to electromagnetic waves with varying frequency. The metasurface consists of disk-like ferroelectric resonators arrayed on a metal film and the upper surface of resonators is covered by ion gel film which is transparent for incident electromagnetic wave. Using the metal film and ion gel film as electrodes, the permittivity of the resonators can be adjusted by an external electric field and, as a result, the reflection phase of the resonators can be dynamically adjusted in a relatively wide range. By programmable controlling the electric field strength applied on resonators of metasurface, a 2π phase ramp can be realized and, thereby, the arbitrary reflection behavior of incident waves with varied frequency is obtained. Because of the tunability, this metasurface can also be used to design adaptive metasurface lens and carpet cloak. PMID:28220861

  19. Torsional Resonators Based on Inorganic Nanotubes.

    PubMed

    Divon, Yiftach; Levi, Roi; Garel, Jonathan; Golberg, Dmitri; Tenne, Reshef; Ya'akobovitz, Assaf; Joselevich, Ernesto

    2017-01-11

    We study for the first time the resonant torsional behaviors of inorganic nanotubes, specifically tungsten disulfide (WS2) and boron nitride (BN) nanotubes, and compare them to that of carbon nanotubes. We have found WS2 nanotubes to have the highest quality factor (Q) and torsional resonance frequency, followed by BN nanotubes and carbon nanotubes. Dynamic and static torsional spring constants of the various nanotubes were found to be different, especially in the case of WS2, possibly due to a velocity-dependent intershell friction. These results indicate that inorganic nanotubes are promising building blocks for high-Q nanoelectromechanical systems (NEMS).

  20. Optical structure based on the acoustic Helmholtz resonator

    NASA Astrophysics Data System (ADS)

    Chevalier, Paul; Bouchon, Patrick; Pelouard, Jean-Luc; Pardo, Fabrice; Haidar, Riad

    2015-02-01

    Here, based on an analogy between acoustics and electromagnetism wave equations, we present an electromagnetic resonator analogous to the Helmholtz resonator in acoustics. This structure is made of a tiny slit above a box and exhibits appealing properties for applications such as thermal emission, bio-sensing or spectroscopy.

  1. Electrical Characterization of a Thiol SAM on Gold as a First Step for the Fabrication of Immunosensors based on a Quartz Crystal Microbalance

    PubMed Central

    Tlili, Asma; Abdelghani, Adnane; Hleli, Salwa; Maaref, Mhamed A.

    2004-01-01

    In order to develop a robust biosensor based on quartz crystal microbalance technique for antigen detection, a control of the steps of the surface functionalization has been performed by impedance spectroscopy. The gold electrode is functionalized with the self-assembled monolayer technique. The high insulating properties of the acidic thiol monolayer has been characterized with cyclic voltammetry and impedance spectroscopy. The modified surface is activated with N-hydroxysuccinimide(NHS) and 1-(3-(dimethylamino)propyl)-3-ethylcarbodimide hydrochloride(EDC) cross-linker for antibody coupling. The non-specific sites are blocked with bovin serum albumine molecules. Different concentrations of antigen can be detected with a good reversibility in real time with the quartz crystal microbalance.

  2. Graphene-based waveguide resonators for submillimeter-wave applications

    NASA Astrophysics Data System (ADS)

    Ilić, Andjelija Ž.; Bukvić, Branko; Ilić, Milan M.; Budimir, Djuradj

    2016-08-01

    Utilization of graphene covered waveguide inserts to form tunable waveguide resonators is theoretically explained and rigorously investigated by means of full-wave numerical electromagnetic simulations. Instead of using graphene-based switching elements, the concept we propose incorporates graphene sheets as parts of a resonator. Electrostatic tuning of the graphene surface conductivity leads to changes in the electromagnetic field boundary conditions at the resonator edges and surfaces, thus producing an effect similar to varying the electrical length of a resonator. The presented outline of the theoretical background serves to give phenomenological insight into the resonator behavior, but it can also be used to develop customized software tools for design and optimization of graphene-based resonators and filters. Due to the linear dependence of the imaginary part of the graphene surface impedance on frequency, the proposed concept was expected to become effective for frequencies above 100 GHz, which is confirmed by the numerical simulations. A frequency range from 100 GHz up to 1100 GHz, where the rectangular waveguides are used, is considered. Simple, all-graphene-based resonators are analyzed first, to assess the achievable tunability and to check the performance throughout the considered frequency range. Graphene-metal combined waveguide resonators are proposed in order to preserve the excellent quality factors typical for the type of waveguide discontinuities used. Dependence of resonator properties on key design parameters is studied in detail. Dependence of resonator properties throughout the frequency range of interest is studied using eight different waveguide sections appropriate for different frequency intervals. Proposed resonators are aimed at applications in the submillimeter-wave spectral region, serving as the compact tunable components for the design of bandpass filters and other devices.

  3. Immunosensor with fluid control mechanism for salivary cortisol analysis.

    PubMed

    Yamaguchi, Masaki; Matsuda, Yohei; Sasaki, Shohei; Sasaki, Makoto; Kadoma, Yoshihiro; Imai, Yoshikatsu; Niwa, Daisuke; Shetty, Vivek

    2013-03-15

    The purpose of this research is to demonstrate a new design for a cortisol immunosensor for the noninvasive and quantitative analysis of salivary cortisol. We propose a cortisol immunosensor with a fluid control mechanism which has both a vertical flow and a lateral flow. The detected current resulting from a competitive reaction between the sample cortisol and a glucose oxidase (GOD)-labeled cortisol conjugate was found to be inversely related to the concentration of cortisol in the sample solution. A calibration curve using the relative detected current showed a R(2)=0.98 and CV=14% for a range of standard cortisol solutions corresponding to the concentrations of native salivary cortisol (0.1-10 ng/ml). The measurement could be accomplished within 35 min and the cortisol immunosensor could be reused. These results show promise for realizing an on-site and easy-to-use biosensor for cortisol. Used for evaluation of human salivary cortisol levels, the cortisol immunosensor measurement corresponded closely with commercially available ELISA method (R(2)=0.92). Our results indicate the promise of the new cortisol immunosensor for noninvasive, point of care measurement of human salivary cortisol levels.

  4. Fano resonance based ultra high-contrast electromagnetic switch

    NASA Astrophysics Data System (ADS)

    Amin, Muhammad; Ramzan, Rashad; Siddiqui, Omar

    2017-05-01

    We experimentally achieve highly asymmetrical enhanced-Q Fano resonances in metallic electromagnetic structures fabricated on conductive planes. We show that the complete destructive interference mechanism of the dark and bright resonant modes generated by a pair of electromagnetically coupled open-ended conductive arms can lead to the asymmetric resonance characterized by a near-unity transparency window followed by a deep scattering band. With the incorporation of a variable capacitor between the coupled metallic strips, the dynamic tunability of the resonant modes is achieved, which can be exploited in high isolation switches and modulators in the GHz spectrum. The switching contrast of over 50 dB achieved through Fano resonance is much higher considering its compact size (i.e., the transmission path is much smaller than the wavelength λ / 30 ). The dispersion based tunable Fano switch offers several advantages over conventional microelectromechanical system and CMOS based switches.

  5. Final Technical Report - In-line Uranium Immunosensor

    SciTech Connect

    Blake, Diane A.

    2006-07-05

    In this project, personnel at Tulane University and Sapidyne Instruments Inc. developed an in-line uranium immunosensor that could be used to determine the efficacy of specific in situ biostimulation approaches. This sensor was designed to operate autonomously over relatively long periods of time (2-10 days) and was able to provide near real-time data about uranium immobilization in the absence of personnel at the site of the biostimulation experiments. An alpha prototype of the in-line immmunosensor was delivered from Sapidyne Instruments to Tulane University in December of 2002 and a beta prototype was delivered in November of 2003. The beta prototype of this instrument (now available commercially from Sapidyne Instruments) was programmed to autonomously dilute standard uranium to final concentrations of 2.5 to 100 nM (0.6 to 24 ppb) in buffer containing a fluorescently labeled anti-uranium antibody and the uranium chelator, 2,9-dicarboxyl-1,10-phenanthroline. The assay limit of detection for hexavalent uranium was 5.8 nM or 1.38 ppb. This limit of detection is well below the drinking water standard of 30 ppb recently promulgated by the EPA. The assay showed excellent precision; the coefficients of variation (CV’s) in the linear range of the assay were less than 5% and CV’s never rose above 14%. Analytical recovery in the immunosensors-based assay was assessed by adding variable known quantities of uranium to purified water samples. A quantitative recovery (93.75% - 108.17%) was obtained for sample with concentrations from 7.5 to 20 nM (2-4.75 ppb). In August of 2005 the sensor was transported to Oak Ridge National Laboratory, for testing of water samples at the Criddle test site (see Wu et al., Environ. Sci. Technol. 40:3978-3985 2006 for a description of this site). In this first on-site test, the in-line sensor was able to accurately detect changes in the concentrations of uranium in effluent samples from this site. Although the absolute values for the

  6. An ultra-sensitive impedimetric immunosensor for detection of the serum oncomarker CA-125 in ovarian cancer patients

    NASA Astrophysics Data System (ADS)

    Johari-Ahar, M.; Rashidi, M. R.; Barar, J.; Aghaie, M.; Mohammadnejad, D.; Ramazani, A.; Karami, P.; Coukos, G.; Omidi, Y.

    2015-02-01

    Effective treatment of ovarian cancer depends upon the early detection of the malignancy. Here, we report on the development of a new nanostructured immunosensor for early detection of cancer antigen 125 (CA-125). A gold electrode was modified with mercaptopropionic acid (MPA), and then consecutively conjugated with silica coated gold nanoparticles (AuNP@SiO2), CdSe quantum dots (QDs) and anti-CA-125 monoclonal antibody (mAb). The engineered MPA|AuNP@SiO2|QD|mAb immunosensor was characterised using transmission electron microscopy (TEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Successive conjugation of AuNP@SiO2, CdSe QD and anti-CA-125 mAb onto the gold electrode resulted in sensitive detection of CA-125 with a limit of detection (LOD) of 0.0016 U mL-1 and a linear detection range (LDR) of 0-0.1 U mL-1. Based on the high sensitivity and specificity of the immunosensor, we propose this highly stable and reproducible biosensor for the early detection of CA-125.Effective treatment of ovarian cancer depends upon the early detection of the malignancy. Here, we report on the development of a new nanostructured immunosensor for early detection of cancer antigen 125 (CA-125). A gold electrode was modified with mercaptopropionic acid (MPA), and then consecutively conjugated with silica coated gold nanoparticles (AuNP@SiO2), CdSe quantum dots (QDs) and anti-CA-125 monoclonal antibody (mAb). The engineered MPA|AuNP@SiO2|QD|mAb immunosensor was characterised using transmission electron microscopy (TEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Successive conjugation of AuNP@SiO2, CdSe QD and anti-CA-125 mAb onto the gold electrode resulted in sensitive detection of CA-125 with a limit of detection (LOD) of 0.0016 U mL-1 and a linear detection range (LDR) of 0-0.1 U mL-1. Based on the high sensitivity and specificity of the immunosensor, we propose

  7. Low density lipoprotein detection based on antibody immobilized self-assembled monolayer: investigations of kinetic and thermodynamic properties.

    PubMed

    Matharu, Zimple; Bandodkar, Amay Jairaj; Sumana, G; Solanki, Pratima R; Ekanayake, E M I Mala; Kaneto, Keiichi; Gupta, Vinay; Malhotra, B D

    2009-10-29

    Human plasma low density lipoprotein (LDL) immunosensor based on surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) was fabricated by immobilizing antiapolipoprotein B (AAB) onto self-assembled monolayer (SAM) of 4-aminothiophenol (ATP). The AAB/ATP/Au immunosensor can detect LDL up to 0.252 microM (84 mg/dL) and 0.360 microM (120 mg/dL) with QCM and SPR, respectively. The SPR and QCM measurements were further utilized to study the reaction kinetics of the AAB-LDL interaction. The adsorption process involved was explored using Langmuir adsorption isotherm and Freundlich adsorption models. The thermodynamic parameters such as change in Gibb's free energy (DeltaG(ads)), change in enthalpy (DeltaH(ads)), and change in entropy (DeltaS(ads)) determined at 283, 298, and 308 K revealed that the AAB-LDL interaction is endothermic in nature and is governed by entropy. Kinetic, thermodynamic, and sticking probability studies disclosed that desorption of the water molecules from the active sites of AAB and LDL plays a key role in the interaction process and increase in temperature favors binding of LDL with the AAB/ATP/Au immunosensor. Thus, the studies were utilized to unravel the most important subprocess involved in the adsorption of LDL onto AAB-modified ATP/Au surface that may help in the fabrication of LDL immunosensors with better efficiency.

  8. Nanoelectrode ensembles as recognition platform for electrochemical immunosensors.

    PubMed

    Mucelli, S Pozzi; Zamuner, M; Tormen, M; Stanta, G; Ugo, P

    2008-07-15

    In this study we demonstrate the possibility to prepare highly sensitive nanostructured electrochemical immunosensors by immobilizing biorecognition elements on nanoelectrode ensembles (NEEs) prepared in track-etch polycarbonate membranes. The gold nanodisk electrodes act as electrochemical transducers while the surrounding polycarbonate binds the antibody-based biorecognition layer. The interaction between target protein and antibody is detected by suitable secondary antibodies labelled with a redox enzyme. A redox mediator, added to the sample solution, shuttles electrons from the nanoelectrodes to the biorecognition layer, so generating an electrocatalytic signal. This allows one to fully exploit the highly improved signal-to-background current ratio, typical of NEEs. In particular, the receptor protein HER2 was studied as the target analyte. HER2 detection allows the identification of breast cancer that can be treated with the monoclonal antibody trastuzumab. NEEs were functionalized with trastuzumab which interacts specifically with HER2. The biorecognition process was completed by adding a primary antibody and a secondary antibody labelled with horseradish peroxidase. Hydrogen peroxide was added to modulate the label electroactivity; methylene blue was the redox mediator generating voltammetric signals. NEEs functionalized with trastuzumab were tested to detect small amounts of HER2 in diluted cell lysates and tumour lysates.

  9. Flow immunosensor detection of explosives and drugs of abuse

    NASA Astrophysics Data System (ADS)

    Kusterbeck, Anne W.; Judd, Linda L.; Yu, Hao; Myles, June; Ligler, Frances S.

    1994-03-01

    An antibody-based biosensor has been developed at the Naval Research Laboratory which is capable of detecting both drugs and explosives present at low levels in an aqueous sample. In the flow immunosensor, antibodies are immobilized onto a solid substrate, allowed to bind a fluorescently labeled signal molecule, placed in a small column and attached to a buffer flow. Upon sample introduction, an amount of the fluorescent signal molecule is released that is proportional to the concentration of applied sample. The response time of the sensor is under a minute, and multiple samples can be analyzed without the need for additional reagents. Quantitative assays are being developed for a variety of compounds, including TNT, DNT, PETN, and cocaine. The laboratory prototype has been used to study how choice of fluorophore, antibody density, and flow rate affect the signal intensity and column lifetime. A self-contained commercial instrument which can analyze up to seven different compounds from a single sample is currently being engineered under a Cooperative Research and Development Agreement.

  10. Tunable color filters based on metal-insulator-metal resonators.

    PubMed

    Diest, Kenneth; Dionne, Jennifer A; Spain, Merrielle; Atwater, Harry A

    2009-07-01

    We report a method for filtering white light into individual colors using metal-insulator-metal resonators. The resonators are designed to support photonic modes at visible frequencies, and dispersion relations are developed for realistic experimental configurations. Experimental results indicate that passive Ag/Si(3)N(4)/Au resonators exhibit color filtering across the entire visible spectrum. Full field electromagnetic simulations were performed on active resonators for which the resonator length was varied from 1-3 microm and the output slit depth was systematically varied throughout the thickness of the dielectric layer. These resonators are shown to filter colors based on interference between the optical modes within the dielectric layer. By careful design of the output coupling, the resonator can selectively couple to intensity maxima of different photonic modes and, as a result, preferentially select any of the primary colors. We also illustrate how refractive index modulation in metal-insulator-metal resonators can yield actively tunable color filters. Simulations using lithium niobate as the dielectric layer and the top and bottom Ag layers as electrodes, indicate that the output color can be tuned over the visible spectrum with an applied field.

  11. An ultrasensitive sandwich-type electrochemical immunosensor based on the signal amplification system of double-deck gold film and thionine unite with platinum nanowire inlaid globular SBA-15 microsphere.

    PubMed

    Wang, Ping; Li, Mingdang; Pei, Fubin; Li, Yueyun; Liu, Qing; Dong, Yunhui; Chu, Qingyan; Zhu, Hongjun

    2017-05-15

    A novel thionine unites with platinum nanowire inlaid globular SBA-15 (Pt NWs@g-SBA-15/Thi) not only utilizes as an efficient electrical signal probe but also constitutes an amplifying system with double-deck gold film (D-Au film) have been applied to the fabrication of sandwich-type immunosensor for detecting hepatitis B surface antigen (HBs Ag). The D-Au film can accelerate the electron transfer on the electrode interface due to the tunneling effect between the two Au films and can improve the load capacity of primary antibodies (Ab1) because of the good biocompatibility. The Pt NWs@g-SBA-15/Thi with uniform globular morphology not only can effectively reduce the spatial limitation for loading the secondary antibodies (Ab2) but also can provide outstanding pore accessibility of guest species from outside and offer catalytically active sites in a large scale. Besides, the presence of Thi can well enhance the electrical conductivity of Pt NWs@g-SBA-15/Thi. With the good cooperation between D-Au film and Pt NWs@g-SBA-15/Thi, a linear relationship between current signals and the concentrations of HBs Ag was obtained in the wide range from 10 fg/mL to 100ng/mL and the detection limit of HBs Ag was 3.3 fg/mL (signal-to-noise ratio of 3). Furthermore, the designed immunosensor with excellent selectivity, reproducibility and stability shows excellent performance in detection of human serum samples and provides a promising capacity for detecting a wide range of other tumor markers in clinical application.

  12. Detection of hexavalent uranium with inline and field-portable immunosensors

    SciTech Connect

    Melton, Scott J.; Yu, Haini; Ali, Mehnaaz F.; Williams, Kenneth H; Wilkins, Michael J.; Long, Philip E.; Blake, Diane A.

    2008-10-02

    An antibody that recognizes a chelated form of hexavalent uranium was used in the development of two different immunosensors for uranium detection. Specifically, these sensors were utilized for the analysis of groundwater samples collected during a 2007 field study of in situ bioremediation in a aquifer located at Rifle, CO. The antibody-based sensors provided data comparable to that obtained using Kinetic Phosphorescence Analysis (KPA). Thus, these novel instruments and associated reagents should provide field researchers and resource managers with valuable new tools for on-site data acquisition.

  13. DNAzyme-functionalized gold-palladium hybrid nanostructures for triple signal amplification of impedimetric immunosensor.

    PubMed

    Hou, Li; Gao, Zhuangqiang; Xu, Mingdi; Cao, Xia; Wu, Xiaoping; Chen, Guonan; Tang, Dianping

    2014-04-15

    A highly sensitive and selective impedimetric immunosensor with triple signal amplification was designed for ultrasensitive detection of prostate-specific antigen (PSA) by using anti-PSA antibody and DNAzyme-functionalized gold-palladium hybrid nanotags (Ab2-AuPd-DNA). The signal was amplified based on the Ab2-AuPd-DNA toward the catalytic precipitation of 4-choloro-1-naphthol (4-CN). DNAzyme (as a kind of peroxidase mimic) could catalyze the oxidation of 4-CN, whilst AuPd hybrid nanostructures could not only provide a large surface coverage for immobilization of biomolecules but also promote 4-CN oxidation to some extent. The produced insoluble benzo-4-chlorohexadienone via 4-CN was coated on the electrode surface, and hindered the electron transfer between the solution and the electrode, thereby increasing the Faradaic impedance of the base electrode. Three labeling strategies including Ab2-AuNP, Ab2-AuPd and Ab2-AuPd-DNA were investigated for determination of PSA, and improved analytical features were obtained with the Ab2-AuPd-DNA strategy. Under optimal conditions, the dynamic concentration range of the impedimetric immunosensor spanned from 1.0 pg mL(-1) to 50 ng mL(-1) PSA with a detection limit of 0.73 pg mL(-1). Intra- and inter-assay coefficients of variation were below 8.5% and 9.5%, respectively. Importantly, no significant differences at the 0.05 significance level were encountered in the analysis of 6 clinical serum specimens and 6 diluted standards between the impedimetric immunosensor and the commercialized electrochemiluminescent method for PSA detection.

  14. Sensitivity improvements of a resonance-based tactile sensor.

    PubMed

    Murayama, Yoshinobu; Lindahl, Olof A

    2017-02-01

    Resonance-based contact-impedance measurement refers to the application of resonance sensors based on the measurement of the changes in the resonance curve of an ultrasonic resonator in contact with a surface. The advantage of the resonance sensor is that it is very sensitive to small changes in the contact impedance. A sensitive micro tactile sensor (MTS) was developed, which measured the elasticity of soft living tissues at the single-cell level. In the present paper, we studied the method of improving the touch and stiffness sensitivity of the MTS. First, the dependence of touch sensitivity in relation to the resonator length was studied by calculating the sensitivity coefficient at each length ranging from 9 to 40 mm. The highest touch sensitivity was obtained with a 30-mm-long glass needle driven at a resonance frequency of 100 kHz. Next, the numerical calculation of contact impedance showed that the highest stiffness sensitivity was achieved when the driving frequency was 100 kHz and the contact-tip diameter of the MTS was 10 μm. The theoretical model was then confirmed experimentally using a phase-locked-loop-based digital feedback oscillation circuit. It was found that the developed MTS, whose resonant frequency was 97.030 kHz, performed with the highest sensitivity of 53.2 × 10(6) Hz/N at the driving frequency of 97.986 kHz, i.e. the highest sensitivity was achieved at 956 Hz above the resonant frequency.

  15. High Quality Factor Mechanical Resonators Based on WSe2 Monolayers.

    PubMed

    Morell, Nicolas; Reserbat-Plantey, Antoine; Tsioutsios, Ioannis; Schädler, Kevin G; Dubin, François; Koppens, Frank H L; Bachtold, Adrian

    2016-08-10

    Suspended monolayer transition metal dichalcogenides (TMD) are membranes that combine ultralow mass and exceptional optical properties, making them intriguing materials for opto-mechanical applications. However, the low measured quality factor of TMD resonators has been a roadblock so far. Here, we report an ultrasensitive optical readout of monolayer TMD resonators that allows us to reveal their mechanical properties at cryogenic temperatures. We find that the quality factor of monolayer WSe2 resonators greatly increases below room temperature, reaching values as high as 1.6 × 10(4) at liquid nitrogen temperature and 4.7 × 10(4) at liquid helium temperature. This surpasses the quality factor of monolayer graphene resonators with similar surface areas. Upon cooling the resonator, the resonant frequency increases significantly due to the thermal contraction of the WSe2 lattice. These measurements allow us to experimentally study the thermal expansion coefficient of WSe2 monolayers for the first time. High Q-factors are also found in resonators based on MoS2 and MoSe2 monolayers. The high quality-factor found in this work opens new possibilities for coupling mechanical vibrational states to two-dimensional excitons, valley pseudospins, and single quantum emitters and for quantum opto-mechanical experiments based on the Casimir interaction.

  16. High Quality Factor Mechanical Resonators Based on WSe2 Monolayers

    PubMed Central

    2016-01-01

    Suspended monolayer transition metal dichalcogenides (TMD) are membranes that combine ultralow mass and exceptional optical properties, making them intriguing materials for opto-mechanical applications. However, the low measured quality factor of TMD resonators has been a roadblock so far. Here, we report an ultrasensitive optical readout of monolayer TMD resonators that allows us to reveal their mechanical properties at cryogenic temperatures. We find that the quality factor of monolayer WSe2 resonators greatly increases below room temperature, reaching values as high as 1.6 × 104 at liquid nitrogen temperature and 4.7 × 104 at liquid helium temperature. This surpasses the quality factor of monolayer graphene resonators with similar surface areas. Upon cooling the resonator, the resonant frequency increases significantly due to the thermal contraction of the WSe2 lattice. These measurements allow us to experimentally study the thermal expansion coefficient of WSe2 monolayers for the first time. High Q-factors are also found in resonators based on MoS2 and MoSe2 monolayers. The high quality-factor found in this work opens new possibilities for coupling mechanical vibrational states to two-dimensional excitons, valley pseudospins, and single quantum emitters and for quantum opto-mechanical experiments based on the Casimir interaction. PMID:27459399

  17. Dual band metamaterial perfect absorber based on Mie resonances

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoming; Lan, Chuwen; Bi, Ke; Li, Bo; Zhao, Qian; Zhou, Ji

    2016-08-01

    We numerically and experimentally demonstrated a polarization insensitive dual-band metamaterial perfect absorber working in wide incident angles based on the two magnetic Mie resonances of a single dielectric "atom" with simple structure. Two absorption bands with simulated absorptivity of 99% and 96%, experimental absorptivity of 97% and 94% at 8.45 and 11.97 GHz were achieved due to the simultaneous magnetic and electric resonances in dielectric "atom" and copper plate. Mie resonances of dielectric "atom" provide a simple way to design metamaterial perfect absorbers with high symmetry.

  18. Ring resonator based narrow-linewidth semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Ksendzov, Alexander (Inventor)

    2005-01-01

    The present invention is a method and apparatus for using ring resonators to produce narrow linewidth hybrid semiconductor lasers. According to one embodiment of the present invention, the narrow linewidths are produced by combining the semiconductor gain chip with a narrow pass band external feedback element. The semi conductor laser is produced using a ring resonator which, combined with a Bragg grating, acts as the external feedback element. According to another embodiment of the present invention, the proposed integrated optics ring resonator is based on plasma enhanced chemical vapor deposition (PECVD) SiO.sub.2 /SiON/SiO.sub.2 waveguide technology.

  19. Dual band metamaterial perfect absorber based on Mie resonances

    SciTech Connect

    Liu, Xiaoming; Lan, Chuwen; Li, Bo; Zhou, Ji; Bi, Ke; Zhao, Qian

    2016-08-08

    We numerically and experimentally demonstrated a polarization insensitive dual-band metamaterial perfect absorber working in wide incident angles based on the two magnetic Mie resonances of a single dielectric “atom” with simple structure. Two absorption bands with simulated absorptivity of 99% and 96%, experimental absorptivity of 97% and 94% at 8.45 and 11.97 GHz were achieved due to the simultaneous magnetic and electric resonances in dielectric “atom” and copper plate. Mie resonances of dielectric “atom” provide a simple way to design metamaterial perfect absorbers with high symmetry.

  20. Multiplexed Electrochemical Immunosensors for Clinical Biomarkers

    PubMed Central

    Yáñez-Sedeño, Paloma; Campuzano, Susana; Pingarrón, José M.

    2017-01-01

    Management and prognosis of disease requires the accurate determination of specific biomarkers indicative of normal or disease-related biological processes or responses to therapy. Moreover since multiple determinations of biomarkers have demonstrated to provide more accurate information than individual determinations to assist the clinician in prognosis and diagnosis, the detection of several clinical biomarkers by using the same analytical device hold enormous potential for early detection and personalized therapy and will simplify the diagnosis providing more information in less time. In this field, electrochemical immunosensors have demonstrated to offer interesting alternatives against conventional strategies due to their simplicity, fast response, low cost, high sensitivity and compatibility with multiplexed determination, microfabrication technology and decentralized determinations, features which made them very attractive for integration in point-of-care (POC) devices. Therefore, in this review, the relevance and current challenges of multiplexed determination of clinical biomarkers are briefly introduced, and an overview of the electrochemical immunosensing platforms developed so far for this purpose is given in order to demonstrate the great potential of these methodologies. After highlighting the main features of the selected examples, the unsolved challenges and future directions in this field are also briefly discussed. PMID:28448466

  1. Electrochemical immunosensors in breast and ovarian cancer.

    PubMed

    Diaconu, Iulia; Cristea, Cecilia; Hârceagă, Veronica; Marrazza, Giovanna; Berindan-Neagoe, Ioana; Săndulescu, Robert

    2013-10-21

    During the last decades the incidence of cancer increased dramatically especially in developed countries. In spite of the fact that the immunochemical methods allowed the diagnosis in early stages, the biopsies are generally invasive methods that create discomfort to patients. The need for fast, sensitive, easy to use and noninvasive diagnosis tools is actually of great interest for many research groups all over the world. Immunosensors (ISs) are miniaturized measuring devices, which selectively detect their targets by means of antibodies (Abs) and provide concentration-dependent signals. Ab binding leads to a variation in electric charge, mass, heat or optical properties, which can be detected directly or indirectly by a variety of transducers. A great number of proteins could be considered as recognition element. In this review the attention was focused on main cancer biomarkers, currently used by immunological methods (immunohistochemistry, ELISA, flow cytometry, Western blot, immunofluorescence etc) and in the development of electrochemical immunoassays that could be used in cancer diagnosis, prognosis and therapy monitoring.

  2. Reliable and integrated technique for determining resonant frequency in radio frequency resonators. Application to a high-precision resonant cavity-based displacement sensor.

    PubMed

    Jauregui, Rigoberto; Asua, Estibaliz; Portilla, Joaquin; Etxebarria, Victor

    2015-03-01

    This paper presents a reliable and integrated technique for determining the resonant frequency of radio frequency resonators, which can be of interest for different purposes. The approach uses a heterodyne scheme as phase detector coupled to a voltage-controlled oscillator. The system seeks the oscillator frequency that produces a phase null in the resonator, which corresponds to the resonant frequency. A complete explanation of the technique to determine the resonant frequency is presented and experimentally tested. The method has been applied to a high-precision displacement sensor based on resonant cavity, obtaining a theoretical nanometric precision.

  3. A self-amplified transistor immunosensor under dual gate operation: highly sensitive detection of hepatitis B surface antigen

    NASA Astrophysics Data System (ADS)

    Lee, I.-K.; Jeun, M.; Jang, H.-J.; Cho, W.-J.; Lee, K. H.

    2015-10-01

    Ion-sensitive field-effect transistors (ISFETs), although they have attracted considerable attention as effective immunosensors, have still not been adopted for practical applications owing to several problems: (1) the poor sensitivity caused by the short Debye screening length in media with high ion concentration, (2) time-consuming preconditioning processes for achieving the highly-diluted media, and (3) the low durability caused by undesirable ions such as sodium chloride in the media. Here, we propose a highly sensitive immunosensor based on a self-amplified transistor under dual gate operation (immuno-DG ISFET) for the detection of hepatitis B surface antigen. To address the challenges in current ISFET-based immunosensors, we have enhanced the sensitivity of an immunosensor by precisely tailoring the nanostructure of the transistor. In the pH sensing test, the immuno-DG ISFET showed superior sensitivity (2085.53 mV per pH) to both standard ISFET under single gate operation (58.88 mV per pH) and DG ISFET with a non-tailored transistor (381.14 mV per pH). Moreover, concerning the detection of hepatitis B surface antigens (HBsAg) using the immuno-DG ISFET, we have successfully detected trace amounts of HBsAg (22.5 fg mL-1) in a non-diluted 1× PBS medium with a high sensitivity of 690 mV. Our results demonstrate that the proposed immuno-DG ISFET can be a biosensor platform for practical use in the diagnosis of various diseases.Ion-sensitive field-effect transistors (ISFETs), although they have attracted considerable attention as effective immunosensors, have still not been adopted for practical applications owing to several problems: (1) the poor sensitivity caused by the short Debye screening length in media with high ion concentration, (2) time-consuming preconditioning processes for achieving the highly-diluted media, and (3) the low durability caused by undesirable ions such as sodium chloride in the media. Here, we propose a highly sensitive immunosensor

  4. Acoustic superlens using Helmholtz-resonator-based metamaterials

    SciTech Connect

    Yang, Xishan; Yin, Jing; Yu, Gaokun Peng, Linhui; Wang, Ning

    2015-11-09

    Acoustic superlens provides a way to overcome the diffraction limit with respect to the wavelength of the bulk wave in air. However, the operating frequency range of subwavelength imaging is quite narrow. Here, an acoustic superlens is designed using Helmholtz-resonator-based metamaterials to broaden the bandwidth of super-resolution. An experiment is carried out to verify subwavelength imaging of double slits, the imaging of which can be well resolved in the frequency range from 570 to 650 Hz. Different from previous works based on the Fabry-Pérot resonance, the corresponding mechanism of subwavelength imaging is the Fano resonance, and the strong coupling between the neighbouring Helmholtz resonators separated at the subwavelength interval leads to the enhanced sound transmission over a relatively wide frequency range.

  5. Acoustic superlens using Helmholtz-resonator-based metamaterials

    NASA Astrophysics Data System (ADS)

    Yang, Xishan; Yin, Jing; Yu, Gaokun; Peng, Linhui; Wang, Ning

    2015-11-01

    Acoustic superlens provides a way to overcome the diffraction limit with respect to the wavelength of the bulk wave in air. However, the operating frequency range of subwavelength imaging is quite narrow. Here, an acoustic superlens is designed using Helmholtz-resonator-based metamaterials to broaden the bandwidth of super-resolution. An experiment is carried out to verify subwavelength imaging of double slits, the imaging of which can be well resolved in the frequency range from 570 to 650 Hz. Different from previous works based on the Fabry-Pérot resonance, the corresponding mechanism of subwavelength imaging is the Fano resonance, and the strong coupling between the neighbouring Helmholtz resonators separated at the subwavelength interval leads to the enhanced sound transmission over a relatively wide frequency range.

  6. Towards the fabrication of a label-free amperometric immunosensor using SWNTs for direct detection of paraoxon.

    PubMed

    Liu, Guozhen; Song, Dandan; Chen, Fengjuan

    2013-01-30

    A label-free immunosensor based on SWNTs modified GC electrodes has been developed for the direct detection of paraoxon. Based on aryldiazonium salt chemistry, forest of SWNTs can be vertically aligned on mixed monolayers of aryldiazonium salt modified GC electrodes by C-C bonding, which provides an interface showing efficient electron transfer between biomolecules. PEG molecules were introduced to the interface to resist non-specific protein adsorption. Ferrocenedimethylamine (FDMA) was subsequently attached to the ends of SWNTs through the amide bonding followed by the attachment of epitope i.e., paraoxon hapten to which a paraoxon antibody would bind. This immunosensor shows good selectivity and high specificity to paraoxon, and is functional for the detection of paraoxon in both laboratory and field by a displacement assay. There is a linear relationship between electrochemical signal of FDMA and the concentration of paraoxon over the range of 2-2500 ppb with a lowest detected limit of 2 ppb in 0.1 M phosphate buffer at pH 7.0. The SWNTs based amperometric immunosensor provides an opportunity to develop the sensing system for on-site sensitive detection of a spectrum of insecticides.

  7. Developing resonant tunneling devices based on graphene

    NASA Astrophysics Data System (ADS)

    Yu, Eric; Tiwari, Sandip; Stewart, Derek

    2009-03-01

    We present an ab-initio study of the electronic properties of patterned graphene structures as candidate resonant tunneling devices. We consider graphene nanoribbons that have been modified with one or more narrow constrictions or patterned with periodic nanoscale antidotes[1]. Specifically, we focus on semi-metallic armchair nanoribbons with narrow semiconducting regions and semi-metallic zigzag nanoribbons patterned with antidots. Using a first-principles density functional theory (DFT) approach, we investigate the induced band-gap opening and transmission coefficients. We examine how varying the lengths of the constrictions, changing the separation between dots and their sizes affect transport properties. We will also discuss I-V characteristics of these graphene structures and evaluate the possibility of a negative differential resistance in these devices. [1] T. G. Pedersen et al., Physical Review Letters, 100 136804 (2008)

  8. A resonance based model of biological evolution

    NASA Astrophysics Data System (ADS)

    Damasco, Achille; Giuliani, Alessandro

    2017-04-01

    We propose a coarse grained physical model of evolution. The proposed model 'at least in principle' is amenable of an experimental verification even if this looks as a conundrum: evolution is a unique historical process and the tape cannot be reversed and played again. Nevertheless, we can imagine a phenomenological scenario tailored upon state transitions in physical chemistry in which different agents of evolution play the role of the elements of a state transition like thermal noise or resonance effects. The abstract model we propose can be of help for sketching hypotheses and getting rid of some well-known features of natural history like the so-called Cambrian explosion. The possibility of an experimental proof of the model is discussed as well.

  9. Label free sensing of creatinine using a 6 GHz CMOS near-field dielectric immunosensor.

    PubMed

    Guha, S; Warsinke, A; Tientcheu, Ch M; Schmalz, K; Meliani, C; Wenger, Ch

    2015-05-07

    In this work we present a CMOS high frequency direct immunosensor operating at 6 GHz (C-band) for label free determination of creatinine. The sensor is fabricated in standard 0.13 μm SiGe:C BiCMOS process. The report also demonstrates the ability to immobilize creatinine molecules on a Si3N4 passivation layer of the standard BiCMOS/CMOS process, therefore, evading any further need of cumbersome post processing of the fabricated sensor chip. The sensor is based on capacitive detection of the amount of non-creatinine bound antibodies binding to an immobilized creatinine layer on the passivated sensor. The chip bound antibody amount in turn corresponds indirectly to the creatinine concentration used in the incubation phase. The determination of creatinine in the concentration range of 0.88-880 μM is successfully demonstrated in this work. A sensitivity of 35 MHz/10 fold increase in creatinine concentration (during incubation) at the centre frequency of 6 GHz is gained by the immunosensor. The results are compared with a standard optical measurement technique and the dynamic range and sensitivity is of the order of the established optical indication technique. The C-band immunosensor chip comprising an area of 0.3 mm(2) reduces the sensing area considerably, therefore, requiring a sample volume as low as 2 μl. The small analyte sample volume and label free approach also reduce the experimental costs in addition to the low fabrication costs offered by the batch fabrication technique of CMOS/BiCMOS process.

  10. A Model of Bone Remodelling Based on Stochastic Resonance

    NASA Astrophysics Data System (ADS)

    Rusconi, M.; Zaikin, A.; Marwan, N.; Kurths, J.

    2008-06-01

    One of the most crucial medical challenges for long-term space flights is the prevention of bone loss affecting astronauts and its dramatic consequences on their return to gravitational field. Recently, a new noise-induced phenomenon in bone formation has been reported experimentally [1]. With this contribution we propose a model for this findings based on Stochastic Resonance [2]. Our simulations suggest new countermeasures for bone degeneration during long space fights using the effect of Stochastic Resonance.

  11. A microprocessor-based multichannel subsensory stochastic resonance electrical stimulator.

    PubMed

    Chang, Gwo-Ching

    2013-01-01

    Stochastic resonance electrical stimulation is a novel intervention which provides potential benefits for improving postural control ability in the elderly, those with diabetic neuropathy, and stroke patients. In this paper, a microprocessor-based subsensory white noise electrical stimulator for the applications of stochastic resonance stimulation is developed. The proposed stimulator provides four independent programmable stimulation channels with constant-current output, possesses linear voltage-to-current relationship, and has two types of stimulation modes, pulse amplitude and width modulation.

  12. Preparation of ring resonator based on PDMS using laser lithography

    NASA Astrophysics Data System (ADS)

    Jandura, D.; Pudis, D.; Gaso, P.

    2016-12-01

    In this paper we present preparation process of ring resonator in racetrack configuration based on polydimethylsiloxane (PDMS). 3D laser lithography in combination with imprinting technique was used to pattern photoresist layer as a master for imprinting process. In the next step, PDMS ring resonator was imprinted and filled with core PDMS. Finally, morphological properties of prepared device were investigated by scanning electron microscope (SEM) and confocal microscope and transmission spectrum measurements were performed.

  13. A self-amplified transistor immunosensor under dual gate operation: highly sensitive detection of hepatitis B surface antigen.

    PubMed

    Lee, I-K; Jeun, M; Jang, H-J; Cho, W-J; Lee, K H

    2015-10-28

    Ion-sensitive field-effect transistors (ISFETs), although they have attracted considerable attention as effective immunosensors, have still not been adopted for practical applications owing to several problems: (1) the poor sensitivity caused by the short Debye screening length in media with high ion concentration, (2) time-consuming preconditioning processes for achieving the highly-diluted media, and (3) the low durability caused by undesirable ions such as sodium chloride in the media. Here, we propose a highly sensitive immunosensor based on a self-amplified transistor under dual gate operation (immuno-DG ISFET) for the detection of hepatitis B surface antigen. To address the challenges in current ISFET-based immunosensors, we have enhanced the sensitivity of an immunosensor by precisely tailoring the nanostructure of the transistor. In the pH sensing test, the immuno-DG ISFET showed superior sensitivity (2085.53 mV per pH) to both standard ISFET under single gate operation (58.88 mV per pH) and DG ISFET with a non-tailored transistor (381.14 mV per pH). Moreover, concerning the detection of hepatitis B surface antigens (HBsAg) using the immuno-DG ISFET, we have successfully detected trace amounts of HBsAg (22.5 fg mL(-1)) in a non-diluted 1× PBS medium with a high sensitivity of 690 mV. Our results demonstrate that the proposed immuno-DG ISFET can be a biosensor platform for practical use in the diagnosis of various diseases.

  14. High sensitivity optical waveguide accelerometer based on Fano resonance.

    PubMed

    Wan, Fenghua; Qian, Guang; Li, Ruozhou; Tang, Jie; Zhang, Tong

    2016-08-20

    An optical waveguide accelerometer based on tunable asymmetrical Fano resonance in a ring-resonator-coupled Mach-Zehnder interferometer (MZI) is proposed and analyzed. A Fano resonance accelerometer has a relatively large workspace of coupling coefficients with high sensitivity, which has potential application in inertial navigation, missile guidance, and attitude control of satellites. Due to the interference between a high-Q resonance pathway and a coherent background pathway, a steep asymmetric line shape is generated, which greatly improves the sensitivity of this accelerometer. The sensitivity of the accelerometer is about 111.75 mW/g. A 393-fold increase in sensitivity is achieved compared with a conventional MZI accelerometer and is approximately equal to the single ring structure.

  15. A wavelength demultiplexing structure based on graphene nanoribbon resonators

    NASA Astrophysics Data System (ADS)

    Zhuang, Huawei; Sheng, Shiwei; Kong, Fanmin; Li, Kang; Wang, Yuling

    2016-12-01

    A wavelength demultiplexing (WDM) structure based on graphene nanoribbon resonators is proposed and numerically investigated by the finite-difference time-domain (FDTD) method. The demultiplexing wavelength can be easily derived by adjusting the length of the resonator, which is accurately explained by the Fabry-Perot (F-P) resonant theory. Meanwhile, the transmission characteristics of the WDM structure are influenced by the coupling distance between the resonator and drop/bus waveguides, and the performance of the WDM device is analyzed at different nanoribbon width and chemical potential. In addition, in order to improve the transmission efficiency from the drop waveguide, a reflection structure is introduced at the end of the bus waveguide. The exact mechanism for the WDM structure is analyzed in detail using the temporal coupled-mode theory. The proposed structure will have potential applications in the field of ultra-compact WDM systems in highly integrated optical circuits.

  16. Porosity estimation of alumina samples based on resonant backscattering spectrometry

    NASA Astrophysics Data System (ADS)

    Mokhles Gerami, F.; Kakuee, O.; Mohammadi, S.

    2016-04-01

    In this work, columnar porous alumina samples were investigated using the 16O(α,α)16O resonance scattering at 3.045 MeV. If the incident energy is slightly above the resonance energy, a resonance peak appears in the energy spectra of the backscattered ions. The position and width of this peak for non-porous samples are mainly determined by the experimental setup, whilst for porous materials, the peak position shifts towards higher energies under certain conditions. This effect can be explained by the lower amount of material which the ions encounter along the backscattered trajectories. The energy shift of the resonance peak towards higher energies was revealed experimentally and discussed theoretically. The estimated porosities of the samples based on this energy shift were compared with those evaluated from the graphical analysis of the images obtained by field emission scanning electron microscopy.

  17. Development of a highly sensitive noncompetitive electrochemical immunosensor for the detection of atrazine by phage anti-immunocomplex assay.

    PubMed

    González-Techera, Andrés; Zon, María Alicia; Molina, Patricia Gabriela; Fernández, Héctor; González-Sapienza, Gualberto; Arévalo, Fernando Javier

    2015-02-15

    The development of immunosensors for the detection of small molecules is of great interest because of their simplicity, high sensitivity and extended analytical range. Due to their size, small compounds cannot be simultaneously recognized by two antibodies impeding their detection by noncompetitive two-site immunoassays, which are superior to competitive ones in terms of sensitivity, kinetics, and working range. In this work, we combine the advantages of magneto-electrochemical immunosensors with the improved sensitivity and direct proportional signal of noncompetitive immunoassays to develop a new Phage Anti-Immunocomplex Electrochemical Immunosensor (PhAIEI) for the detection of the herbicide atrazine. The noncompetitive assay is based on the use of recombinant M13 phage particles bearing a peptide that specifically recognizes the immunocomplex of atrazine with an anti-atrazine monoclonal antibody. The PhAIEI performed with a limit of detection (LOD) of 0.2 pg mL(-1), which is 200-fold better than the LOD obtained using the same antibody in an optimized conventional competitive ELISA, with a large increase in working range. The developed PhAIEI was successfully used to assay undiluted river water samples with no pretreatment and excellent recoveries. Apart from the first demonstration of the benefits of integrating phage anti-immunocomplex particles into electrochemical immunosensors, the extremely low and environmentally relevant detection limits of atrazine attained with the PhAIEIS may have direct applicability to fast and sensitive detection of this herbicide in the environment. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Label-free impedimetric immunosensor for ultrasensitive detection of cancer marker Murine double minute 2 in brain tissue.

    PubMed

    Elshafey, Reda; Tlili, Chaker; Abulrob, Abedelnasser; Tavares, Ana C; Zourob, Mohammed

    2013-01-15

    The detection of cancer biomarkers is as important tool for the diagnosis and prognosis of cancer such as brain cancer. Murine double minute 2 (MDM2) has been widely studied as prognostic marker for brain tumor. Here we describe development of a new sensitive label free impedimetric immunosensor for the detection of MDM2 based on cysteamine self assembled monolayers on a clean polycrystalline Au electrode surface. The amine-modified electrodes were further functionalized with antibody using homobifunctional 1,4-phenylene diisothiocyanate (PDITC) linker. The assembly processes of the immunosensor had been monitored with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques using Fe(CN)(6)(3-/4-) solution as redox probe. The impedance changes upon binding of MDM2 protein to the sensor surface was utilized for the detection of MDM2. The increase in relative electron-transfer resistance (ΔR/R(0)%) values was linearly proportional to the concentration of tumor marker MDM2 in the wide dynamic range of 1pg/ml-1μg/ml. The limit of detection was 0.29pg/ml in phosphate buffer saline (PBS) and 1.3pg/ml in mouse brain tissue homogenate, respectively. The immunosensor showed a good performance in comparison with ELISA for the analysis of the MDM2 in the cancerous mouse brain tissue homogenates. Moreover, the immunosensor had a good selectivity against epidermal growth factor receptor (EGFR) protein, long-storage stability and reproducibility. It might be become a promising assay for clinical diagnosis and early detection of tumors.

  19. Detection of Human IgG on Poly(pyrrole-3-carboxylic acid) Thin Film by Electrochemical-Surface Plasmon Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Janmanee, Rapiphun; Baba, Akira; Phanichphant, Sukon; Sriwichai, Saengrawee; Shinbo, Kazunari; Kato, Keizo; Kaneko, Futao

    2011-01-01

    An electrochemically controlled surface plasmon resonance (SPR) immunosensor for the detection of human immunoglobulin G (IgG) has been developed using poly(pyrrole-3-carboxylic acid) (PP3C) film. In this work, a pyrrole-3-carboxylic acid monomer was used for electropolymerization of a PP3C film on a gold-coated high-refractive-index glass slide. In situ electrochemical (EC)-SPR spectroscopy was performed to study the kinetic property and electroactivity property of the PP3C film. Moreover, ultraviolet-visible (UV-vis) spectroscopy was performed to characterize the PP3C film. Finally, the immunosensor-based PP3C film was constructed. The carboxylic acid surface of the PP3C film was activated for the immobilization of anti-human IgG. The immunosensor electrode was used for probing the binding reaction of anti-human IgG/human IgG with several concentrations of human IgG at different constant applied potentials. The probe immobilization and immunosensing process were in situ monitored by EC-SPR technique. The sensitivity of the sensor was improved by controlling the morphology of the PP3C film by applying the potential.

  20. Label-free electrochemiluminescence immunosensor for cardiac troponin I using luminol functionalized gold nanoparticles as a sensing platform.

    PubMed

    Li, Fang; Yu, Yuqi; Cui, Hua; Yang, Di; Bian, Zhiping

    2013-03-21

    A simple and sensitive label-free electrochemiluminescence (ECL) immunosensor based on the use of luminol functionalized gold nanoparticles (luminol-AuNPs) as antibody carriers and sensing platform is described for detecting the acute myocardial infarction biomarker cTnI. The ECL immunosensor was fabricated by the assembly of luminol-AuNPs conjugated with biotinylated antibodies against cTnI (biotin-anti-cTnI-luminol-AuNPs) with the streptavidin coated AuNPs (SA-AuNPs) modified Au electrode directly by virtue of the biotin-SA system. The fabricated sensing platform exhibited stable and strong ECL intensity and could be used for the recognition of target antigen. In the presence of cTnI, a decrease in the ECL intensity was observed. Direct detection of the ECL signal changes during antigen-antibody immunoreactions can be used for the quantification of cTnI. The ECL response exhibited a quite wide dynamic range from 1000 ng mL(-1) down to 0.1 ng mL(-1). The proposed method has been successfully applied in the detection of cTnI in real plasma samples. This protocol is simple, fast, sensitive, specific, stable and reliable. This work reveals that the luminol-AuNPs are excellent sensing platforms for the fabrication of simple and sensitive immunosensors. Moreover, the proposed strategy may also be extended for the detection of other biomarkers, which is of great application potential in clinical and pharmaceutical analysis.

  1. Development of a nanostructured immunosensor for early and in situ detection of Xanthomonas arboricola in agricultural food production.

    PubMed

    Regiart, Matías; Rinaldi-Tosi, Martin; Aranda, Pedro R; Bertolino, Franco A; Villarroel-Rocha, Jhonny; Sapag, Karim; Messina, Germán A; Raba, Julio; Fernández-Baldo, Martín A

    2017-12-01

    We report a microfluidic electrochemical immunosensor for Xanthomonas arboricola (XA) determination, based on the covalently immobilization of monoclonal anti-XA antibody (anti-XA) on a previously amino functionalized SBA-15 in situ synthesized in the central channel of a glass-poly(dimethylsiloxane) microfluidic immunosensor. The synthetized amino-SBA-15 was characterized by N2 adsorption-desorption isotherm, scanning electron microscopy and infrared spectroscopy. XA was detected by a direct sandwich immunoassay through an alkaline phosphatase (AP) enzyme-labeled anti-XA conjugate. Later, the substrate p-aminophenyl phosphate was converted to p-aminophenol by AP. The enzymatic product was detected at +100mV on a sputtered gold electrode. The measured current was directly proportional to the level of XA in walnut trees samples. The linear range was from 5 × 10(2) to 1 × 10(4)CFUmL(-1). The detection limit was 1.5 × 10(2)CFUmL(-1), and the within- and between-assay coefficients of variation were below 5%. Microfluidic immunosensor is a very promising tool for the early and in situ diagnosis of XA in walnuts avoiding serious economic losses. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. A multi-walled carbon nanotubes-poly(L-lysine) modified enantioselective immunosensor for ofloxacin by using multi-enzyme-labeled gold nanoflower as signal enhancer.

    PubMed

    He, Zuyu; Zang, Shuai; Liu, Yingju; He, Yuan; Lei, Hongtao

    2015-11-15

    The enantioselective detection of trace amounts of ofloxacin is very important in many fields. In this work, an enantioselective and sensitive electrochemical immunosensor was constructed for the detection of chiral antibiotic ofloxacin based on a dual amplification strategy using multiwall carbon nanotubes-poly(L-lysine) as a matrix to immobilize the antigen and multi-enzyme-antibody functionalized gold nanoflowers as an electrochemical detection label. The fabrication process of the dual-amplified immunosensor was characterized by scanning electron microscopy, cyclic voltammogram and electrochemical impedance spectroscopy, respectively. After the optimization of the experimental conditions, a competitive immunoassay, i.e., the association ability with the corresponding antibody between the captured antigen and free S-OFL or R-OFL in the solution, showed that the immunosensor exhibited a sensitive response to S-OFL in the range from 0.26 to 25.6 ng/mL with a detection limit of 0.15 ng/mL as well as a sensitive response to R-OFL in the range from 0.37 to 12.8 ng/mL with a detection limit of 0.30 ng/mL. Along with the acceptable sensitivity and stability, the S-OFL or R-OFL immunosensor showed selective ability to its corresponding enantiomer, suggesting this amplification strategy may hold a potential application in the detection of OFL in food or environment. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. A promising magnetic SERS immunosensor for sensitive detection of avian influenza virus.

    PubMed

    Sun, Yang; Xu, Li; Zhang, Fengdi; Song, Zhigang; Hu, Yunwen; Ji, Yongjia; Shen, Jiayin; Li, Ben; Lu, Hongzhou; Yang, Haifeng

    2017-03-15

    Avian influenza viruses infect a great number of global populations every year and can lead to severe epidemics with high morbidity and mortality. Facile, rapid and sensitive detection of viruses is very crucial to control the viral spread at its early stage. In this work, we developed a novel magnetic immunosensor based on surface enhanced Raman scattering (SERS) spectroscopy to detect intact but inactivated influenza virus H3N2 (A/Shanghai/4084T/2012) by constructing a sandwich complex consisting of SERS tags, target influenza viruses and highly SERS-active magnetic supporting substrates. The procedure of sample pretreatment could be significantly simplified since the magnetic supporting substrates allowed the enrichment and separation of viruses from a complex matrix. With a portable Raman spectrometer, the immunosensor could detect H3N2 down to 10(2)TCID50/mL (TCID50 refers to tissue culture infection dose at 50% end point), with a good linear relationship from 10(2) to 5×10(3) TCID50/mL. Considering its time efficiency, portability and sensitivity, the proposed SERS-based magnetic immunoassay is very promising for a point-of-care (POC) test in clinical and diagnostic praxis.

  4. GaAs-based micro/nanomechanical resonators

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hiroshi

    2017-10-01

    Micro/nanomechanical resonators have been extensively studied both for device applications, such as high-performance sensors and high-frequency devices, and for fundamental science, such as quantum physics in macroscopic objects. The advantages of GaAs-based semiconductor heterostructures include improved mechanical properties through strain engineering, highly controllable piezoelectric transduction, carrier-mediated optomechanical coupling, and hybridization with quantum low-dimensional structures. This article reviews our recent activities, as well as those of other groups, on the physics and applications of mechanical resonators fabricated using GaAs-based heterostructures.

  5. A time domain based method for the accurate measurement of Q-factor and resonance frequency of microwave resonators

    SciTech Connect

    Gyüre, B.; Márkus, B. G.; Bernáth, B.; Simon, F.; Murányi, F.

    2015-09-15

    We present a novel method to determine the resonant frequency and quality factor of microwave resonators which is faster, more stable, and conceptually simpler than the yet existing techniques. The microwave resonator is pumped with the microwave radiation at a frequency away from its resonance. It then emits an exponentially decaying radiation at its eigen-frequency when the excitation is rapidly switched off. The emitted microwave signal is down-converted with a microwave mixer, digitized, and its Fourier transformation (FT) directly yields the resonance curve in a single shot. Being a FT based method, this technique possesses the Fellgett (multiplex) and Connes (accuracy) advantages and it conceptually mimics that of pulsed nuclear magnetic resonance. We also establish a novel benchmark to compare accuracy of the different approaches of microwave resonator measurements. This shows that the present method has similar accuracy to the existing ones, which are based on sweeping or modulating the frequency of the microwave radiation.

  6. A time domain based method for the accurate measurement of Q-factor and resonance frequency of microwave resonators

    NASA Astrophysics Data System (ADS)

    Gyüre, B.; Márkus, B. G.; Bernáth, B.; Murányi, F.; Simon, F.

    2015-09-01

    We present a novel method to determine the resonant frequency and quality factor of microwave resonators which is faster, more stable, and conceptually simpler than the yet existing techniques. The microwave resonator is pumped with the microwave radiation at a frequency away from its resonance. It then emits an exponentially decaying radiation at its eigen-frequency when the excitation is rapidly switched off. The emitted microwave signal is down-converted with a microwave mixer, digitized, and its Fourier transformation (FT) directly yields the resonance curve in a single shot. Being a FT based method, this technique possesses the Fellgett (multiplex) and Connes (accuracy) advantages and it conceptually mimics that of pulsed nuclear magnetic resonance. We also establish a novel benchmark to compare accuracy of the different approaches of microwave resonator measurements. This shows that the present method has similar accuracy to the existing ones, which are based on sweeping or modulating the frequency of the microwave radiation.

  7. Design and Analyses of a MEMS Based Resonant Magnetometer.

    PubMed

    Ren, Dahai; Wu, Lingqi; Yan, Meizhi; Cui, Mingyang; You, Zheng; Hu, Muzhi

    2009-01-01

    A novel design of a MEMS torsional resonant magnetometer based on Lorentz force is presented and fabricated. The magnetometer consists of a silicon resonator, torsional beam, excitation coil, capacitance plates and glass substrate. Working in a resonant condition, the sensor's vibration amplitude is converted into the sensing capacitance change, which reflects the outside magnetic flux-density. Based on the simulation, the key structure parameters are optimized and the air damping effect is estimated. The test results of the prototype are in accordance with the simulation results of the designed model. The resolution of the magnetometer can reach 30 nT. The test results indicate its sensitivity of more than 400 mV/μT when operating in a 10 Pa vacuum environment.

  8. Design and Analyses of a MEMS Based Resonant Magnetometer

    PubMed Central

    Ren, Dahai; Wu, Lingqi; Yan, Meizhi; Cui, Mingyang; You, Zheng; Hu, Muzhi

    2009-01-01

    A novel design of a MEMS torsional resonant magnetometer based on Lorentz force is presented and fabricated. The magnetometer consists of a silicon resonator, torsional beam, excitation coil, capacitance plates and glass substrate. Working in a resonant condition, the sensor’s vibration amplitude is converted into the sensing capacitance change, which reflects the outside magnetic flux-density. Based on the simulation, the key structure parameters are optimized and the air damping effect is estimated. The test results of the prototype are in accordance with the simulation results of the designed model. The resolution of the magnetometer can reach 30 nT. The test results indicate its sensitivity of more than 400 mV/μT when operating in a 10 Pa vacuum environment. PMID:22399981

  9. Resonant microsphere gyroscope based on a double Faraday rotator system.

    PubMed

    Xie, Chengfeng; Tang, Jun; Cui, Danfeng; Wu, Dajin; Zhang, Chengfei; Li, Chunming; Zhen, Yongqiu; Xue, Chenyang; Liu, Jun

    2016-10-15

    The resonant microsphere gyroscope is proposed based on a double Faraday rotator system for the resonant microsphere gyroscope (RMSG) that is characterized by low insertion losses and does not destroy the reciprocity of the gyroscope system. Use of the echo suppression structure and the orthogonal polarization method can effectively inhibit both the backscattering noise and the polarization error, and reduce them below the system sensitivity limit. The resonance asymmetry rate dropped from 34.2% to 2.9% after optimization of the backscattering noise and the polarization noise, which greatly improved the bias stability and the scale factor linearity of the proposed system. Additionally, based on the optimum parameters for the double Faraday rotator system, a bias stability of 0.04°/s has been established for an integration time of 10 s in 1000 s in a resonator microsphere gyroscope using a microsphere resonator with a diameter of 1 mm and a Q of 7.2×106.

  10. Graphene quantum dot modified screen printed immunosensor for the determination of parathion.

    PubMed

    Mehta, Jyotsana; Bhardwaj, Neha; Bhardwaj, Sanjeev K; Tuteja, Satish K; Vinayak, Priya; Paul, A K; Kim, Ki-Hyun; Deep, Akash

    2017-02-02

    The widespread use of pesticides has immense effect on increased crop productions. However, they are also responsible for posing detrimental health hazards and/or for contaminating the environment with chemical residues. A routine and an on-field detection of pesticide residues in different food, water, and soil samples has become a need of the hour for which biosensors can offer a viable alternative. The present work reports a functionalized graphene quantum dot (GQD) based screen printed electrochemical immunosensor for the detection of parathion. The application of GQDs has permitted the realization of a sensitive, robust, and reproducible sensor unlike those carried out earlier for the similar purposes. This immunosensor exhibited a dynamic linear response for parathion within the range of 0.01-10(6) ng/L with a very low detection limit of 46 pg/L. According to the analysis of potential interferences, the proposed sensor was specifically detecting parathion even in the presence of its metabolite, paraoxon. The investigations of the proposed sensing approach with respect to stability, response reproducibility, and regeneration have fully supported its potential practical applicability.

  11. Photochemical attachment of biomolecules onto fibre-optics for construction of a chemiluminescent immunosensor.

    PubMed

    Leshem, Boaz; Sarfati, Gadi; Novoa, Andres; Breslav, Igor; Marks, Robert S

    2004-01-01

    We report herein a simple and effective way to photochemically immobilize biomolecules onto a fibre-optic silica surface. The system is based on a photoreactive benzophenone derivative that is bound to SiO2 surfaces of the optical fibre via a silane anchor. The benzophenone derivative was 4-allyloxybenzophenone, synthesized by standard procedures that were later used to synthesize the 4-(3'-chlorodimethylsilyl) propyloxybenzophenone and 4-(3'-dichloromethylsilyl) propyloxybenzophenone by regular hydrosilation procedures. After silanization with the benzophenone derivatives, the fibres were immersed in a cholera toxin B subunit solution and illuminated with UV light (wavelength > 345 nm). As a result of the photochemical reaction, a thin layer of the antigen was covalently bound to the benzophenone-modified surface. The photochemically modified fibre-optics were then tested as immunosensors in the detection of cholera anti-toxin antibody and revealed through chemiluminescence measurements. A secondary antibody labelled with horseradish peroxidase acted as the marker for the cholera toxin antibody. A photo-electronic set-up was designed specifically to monitor the signal. The immunosensor system was shown to be both specific and sensitive. The lowest rabbit serum titre detected was 1:1 700,000. Copyright 2004 John Wiley & Sons, Ltd.

  12. A piezoelectric immunosensor for the determination of pesticide residues and metabolites in fruit juices.

    PubMed

    March, C; Manclús, J J; Jiménez, Y; Arnau, A; Montoya, A

    2009-05-15

    A quartz crystal microbalance (QCM) immunosensor was developed for the determination of the insecticide carbaryl and 3,5,6-trichloro-2-pyridinol (TCP), the main metabolite of the insecticide chlorpyrifos and of the herbicide triclopyr. The detection was based on a competitive conjugate-immobilized immunoassay format using monoclonal antibodies (MAbs). Hapten conjugates were covalently immobilized, via thioctic acid self-assembled monolayer (SAM), onto the gold electrode sensitive surface of the quartz crystal. This covalent immobilization allowed the reusability of the modified electrode surface for at least one hundred and fifty assays without significant loss of sensitivity. The piezoimmunosensor showed detection limits (analyte concentrations producing 10% inhibition of the maximum signal) of 11 and 7 microg l(-1) for carbaryl and TCP, respectively. The sensitivity attained (I(50) value) was around 30 microg l(-1) for both compounds. Linear working ranges were 15-53 microg l(-1) for carbaryl and 13-83 microg l(-1) for TCP. Each complete assay cycle took 20 min. The good sensitivity, specificity, and reusability achieved, together with the short response time, allowed the application of this immunosensor to the determination of carbaryl and TCP in fruits and vegetables at European regulatory levels, with high precision and accuracy.

  13. One-step synthesis of potassium ferricyanide-doped polyaniline nanoparticles for label-free immunosensor.

    PubMed

    He, Sijing; Wang, Qiyou; Yu, Yanyan; Shi, Qiujia; Zhang, Lin; Chen, Zuanguang

    2015-06-15

    A novel, label-free and inherent electroactive redox immunosensor for ultrasensitive detection of carcinoembryonic antigen (CEA) was proposed based on gold nanoparticles (AuNPs) and potassium ferricyanide-doped polyaniline (FC-PANI) nanoparticles. FC-PANI composite was synthesized via oxidative polymerization of aniline, using potassium ferricyanide (K3[Fe(CN)6]) as both oxidant and dopant. FC-PANI acting as the signal indicator was first fixed on a gold electrode (GE) to be the signal layer. Subsequently, the negatively charged AuNPs could be adsorbed on the positively charged FC-PANI modified GE surface by electrostatic adsorption, and then to immobilize CEA antibody (anti-CEA) for the assay of CEA. The CEA concentration was measured through the decrease of amperometric signals in the corresponding specific binding of antigen and antibody. The wide linear range of the immunosensor was from 1.0 pg mL(-1) to 500.0 ng mL(-1) with a low detection limit of 0.1 pg mL(-1) (S/N=3). The proposed method would have a potential application in clinical immunoassays with the properties of facile procedure, stability, high sensitivity and selectivity.

  14. An impedimetric immunosensor for the detection of autoantibodies directed against gliadins.

    PubMed

    Balkenhohl, T; Lisdat, F

    2007-04-01

    An immunosensor has been developed for the detection of autoantibodies directed against wheat gliadin, a protein fraction of cereal gluten which is involved in celiac disease. The immunosensor is based on the immobilization of gliadins onto gold electrodes covered with a polyelectrolyte layer of poly(4-styrenesulfonic acid sodium salt). The immobilization was monitored by quartz crystal microbalance (QCM) analysis. The antigen-antibody interaction signal was amplified by an incubation step with peroxidase-labeled immunoglobulins and subsequent peroxidase-catalyzed oxidation of 3-amino-9-ethylcarbazole (AEC). Changes in the insulating properties of the electrode layer were measured by electrochemical impedance spectroscopy (EIS) in the presence of ferri/ferro-cyanide. Impedance spectra could be fitted to a Randles equivalent circuit with high accuracy. Exposing the sensor electrodes to various antigliadin antibody concentrations resulted in proportional changes in the charge transfer resistance. A calibration graph for the detection of antigliadin antibodies was established for antibody concentrations between 10(-8) and 10(-6) M. Finally, the sensor was used for the determination of antigliadin autoantibodies of the IgG and IgA type in several human sera.

  15. Electrochemical immunosensor for ethinylestradiol using diazonium salt grafting onto silver nanoparticles-silica-graphene oxide hybrids.

    PubMed

    Cincotto, Fernando H; Martínez-García, Gonzalo; Yáñez-Sedeño, Paloma; Canevari, Thiago C; Machado, S A S; Pingarrón, José M

    2016-01-15

    This work describes the preparation of an electrochemical immunosensor for ethinylestradiol (EE2) based on grafting of diazonium salt of 4-aminobenzoic acid onto a glassy carbon electrode modified with silver nanoparticles/SiO2/graphene oxide hybrid followed by covalent binding of anti-ethinylestradiol (anti-EE2) to activated carboxyl groups. A competitive immunoassay was developed for the determination of the hormone using peroxidase-labeled ethinylestradiol (HRP-EE2) and measurement of the amperometric response at -200mV in the presence of hydroquinone (HQ) as redox mediator. The calibration curve for EE2 exhibited a linear range between 0.1 and 50ng/mL (r(2)=0.996), with a detection limit of 65pg/mL. Interference studies with other hormones related with EE2 revealed the practical specificity of the developed method for the analyte. A good reproducibility, with RSD=4.5% (n=10) was also observed. The operating stability of a single bioelectrode modified with anti-EE2 was maintained at least for 15 days when it was stored at 4°C under humid conditions between measurements. The developed immunosensor was applied to the analysis of spiked urine with good results.

  16. A label-free immunosensor for diagnosis of Dengue infection with simple electrical measurements.

    PubMed

    Fang, Xiaoqin; Tan, Ooi Kiang; Tse, Man Siu; Ooi, Eng Eong

    2010-01-15

    The interdigitated electrodes and electrical measurements for the diagnosis of dengue infection using antigen-antibody conjugation method are reported. As a proof of concept, pre-inactivated dengue virus was firstly immobilized indirectly onto the immunosensor surface, pre-coated with sol-gel derived barium strontium titanate (BST) thin film and modified with organic self-assembled monolayer (SAM) formed by 3-aminopropyltriethoxysilane (APTS) and a cross-linker glutaraldehyde over the interdigitated electrodes. The modified sensor surface served as selective sensing probe to capture/conjugate the dengue antibody molecules present in patient's serum. Our immunosensor is based on non-faradaic process, using only de-ionized water as electrolyte during the simple electrical measurements. Both ac impedance spectroscopy and dc I-V measurements between the electrodes gave a clearly discernable and repeatable signal to positively identify the presence of dengue antibody in the serum. Direct correlation was obtained between the signal outputs with respect to antibody concentrations. The measured signal changes in impedance/current without/with the presence of dengue antibody were attributed to the surface conductivity change upon biomolecules immobilization and the dipole-induced interfacial polarization potential at the SAM film/biomolecules interface. By monitoring the impedance or current change, the antibody molecules in the patient's serum could be positively detected. Copyright 2009 Elsevier B.V. All rights reserved.

  17. Tailored carbon nanotube immunosensors for the detection of microbial contamination.

    PubMed

    Prieto-Simón, B; Bandaru, N M; Saint, C; Voelcker, N H

    2015-05-15

    The use of carbon nanotubes (CNTs) as building blocks in the design of electrochemical biosensors has been attracting attention over the last few years, mainly due to their high electrical conductivity and large surface area. Here, we present two approaches based on tailored single-walled CNTs (SWCNTs) architectures to develop immunosensors for the bacteriophage MS2, a virus often detected in sewage-impacted water supplies. In the first approach, SWCNTs were used in the bottom-up design of sensors as antibody immobilization support. Carboxy-functionalised SWCNTs were covalently tethered onto gold electrodes via carbodiimide coupling to cysteamine-modified gold electrodes. These SWCNTs were hydrazide functionalized by electrochemical grafting of diazonium salts. Site-oriented immobilization of antibodies was then carried out through hydrazone bond formation. Results showed microarray electrode behavior, greatly improving the signal-to-noise ratio. Excellent sensitivity and limit of detection (9.3 pfu/mL and 9.8 pfu/mL in buffer and in river water, respectively) were achieved, due to the combination of the SWCNTs' ability to promote electron transfer reactions with electroactive species at low overpotentials and their high surface-to-volume ratio providing a favorable environment to immobilize biomolecules. In the second approach, SWCNTs were decorated with iron oxide nanoparticles. Diazonium salts were electrochemically grafted on iron-oxide-nanoparticle-decorated SWCNTs to functionalize them with hydrazide groups that facilitate site-directed immobilization of antibodies via hydrazone coupling. These magnetic immunocarriers facilitated MS2 separation and concentration on an electrode surface. This approach minimized non-specific adsorptions and matrix effects and allowed low limits of detection (12 pfu/mL and 39 pfu/mL in buffer and in river water, respectively) that could be further decreased by incubating the magnetic immunocarriers with larger volumes of sample

  18. THz Emission Based On Intersubband Plasmon Resonances

    SciTech Connect

    Coquelin, M.; Zobl, R.; Strasser, G.; Gornik, E.; Bakshi, P.; Umansky, V.; Heiblum, M.

    2010-01-04

    The radiative decay of collective plasma oscillations as a new mechanism for THz emission is studied. This phenomenon is based on the attractive interaction of two intersubband plasmons. This interaction can be viewed as a collective e-e scattering phenomenon. The emission results fit very well to the results of the current voltage measurements indicating that the conditions for a plasma instability are reached.

  19. Particle densitometer based on the acoustical resonance measurement

    SciTech Connect

    Vetter, A.A.

    1990-10-01

    Work continued on development of a particle densitometer based on the Acoustical Resonance Measurement to monitor pneumatically conveyed particle mass loading. During this quarter, the closed-loop test system was used for testing and an open-loop test system was constructed. 3 figs.

  20. Magnetically tunable Mie resonance-based dielectric metamaterials.

    PubMed

    Bi, Ke; Guo, Yunsheng; Liu, Xiaoming; Zhao, Qian; Xiao, Jinghua; Lei, Ming; Zhou, Ji

    2014-11-11

    Electromagnetic materials with tunable permeability and permittivity are highly desirable for wireless communication and radar technology. However, the tunability of electromagnetic parameters is an immense challenge for conventional materials and metamaterials. Here, we demonstrate a magnetically tunable Mie resonance-based dielectric metamaterials. The magnetically tunable property is derived from the coupling of the Mie resonance of dielectric cube and ferromagnetic precession of ferrite cuboid. Both the simulated and experimental results indicate that the effective permeability and permittivity of the metamaterial can be tuned by modifying the applied magnetic field. This mechanism offers a promising means of constructing microwave devices with large tunable ranges and considerable potential for tailoring via a metamaterial route.

  1. Magnetically tunable Mie resonance-based dielectric metamaterials

    NASA Astrophysics Data System (ADS)

    Bi, Ke; Guo, Yunsheng; Liu, Xiaoming; Zhao, Qian; Xiao, Jinghua; Lei, Ming; Zhou, Ji

    2014-11-01

    Electromagnetic materials with tunable permeability and permittivity are highly desirable for wireless communication and radar technology. However, the tunability of electromagnetic parameters is an immense challenge for conventional materials and metamaterials. Here, we demonstrate a magnetically tunable Mie resonance-based dielectric metamaterials. The magnetically tunable property is derived from the coupling of the Mie resonance of dielectric cube and ferromagnetic precession of ferrite cuboid. Both the simulated and experimental results indicate that the effective permeability and permittivity of the metamaterial can be tuned by modifying the applied magnetic field. This mechanism offers a promising means of constructing microwave devices with large tunable ranges and considerable potential for tailoring via a metamaterial route.

  2. MEMS tunable optical filter based on multi-ring resonator

    SciTech Connect

    Dessalegn, Hailu E-mail: tsrinu@ece.iisc.ernet.in; Srinivas, T. E-mail: tsrinu@ece.iisc.ernet.in

    2014-10-15

    We propose a novel MEMS tunable optical filter with a flat-top pass band based on multi-ring resonator in an electrostatically actuated microcantilever for communication application. The filter is basically structured on a microcantilever beam and built in optical integrated ring resonator which is placed in one end of the beam to gain maximum stress on the resonator. Thus, when a DC voltage is applied, the beam will bend, that induces a stress and strain in the ring, which brings a change in refractive index and perimeter of the rings leading to change in the output spectrum shift, providing the tenability as high as 0.68nm/μN and it is capable of tuning up to 1.7nm.

  3. Circularly split-ring-resonator-based frequency-reconfigurable antenna

    NASA Astrophysics Data System (ADS)

    Rahman, M. A.; Faruque, M. R. I.; Islam, M. T.

    2017-01-01

    In this paper, an antenna with frequency configurability in light of a circularly split-ring resonator (CSRR) is introduced. The proposed reconfigurable monopole antenna consists of a microstrip-fed hook-shaped structure and a CSRR having single reconfigurable split only. A new band of radiation unlike the band radiated from monopole only is observed due to magnetic coupling between the CSRR and the monopole antenna. The resonance frequency of the CSRR can be arbitrarily chosen by varying the dimension and relative position of its gap with the monopole, which leads the antenna to become reconfigurable one. By using a single switch with perfect electric conductor at the gap of CSRR cell, the effect of CSRR can be deactivated and, hence, it is possible to suppress the corresponding resonance, resulting in a frequency-reconfigurable antenna. Commercially available Computer Simulation Technology microwave studio based on finite integration technique was adopted throughout the study.

  4. A Wireless, Passive Load Cell based on Magnetoelastic Resonance.

    PubMed

    Pereles, Brandon D; Dienhart, Thomas; Sansom, Thadeus; Johnston, Kyle; Ong, Keat Ghee

    2012-07-01

    A wireless, battery-less load cell was fabricated based on the resonant frequency shift of a vibrating magnetoelastic strip when exposed to an AC magnetic field. Since the vibration of the magnetoelastic strip generated a secondary field, the resonance was remotely detected with a coil. When a load was applied to a small area on the surface of the magnetoelastic strip via a circular rod applicator, the resonant frequency and amplitude decreased due to the damping on its vibration. The force sensitivity of the load cell was controlled by changing the size of the force applicator and placing the applicator at different locations on the strip's surface. Experimental results showed the force sensitivity increased with a larger applicator placing near the edge of the strip. The novelty of this load cell is not only its wireless passive nature, but also the controllability of the force sensitivity.

  5. Resonant mode for gravitational wave detectors based on atom interferometry

    NASA Astrophysics Data System (ADS)

    Graham, Peter W.; Hogan, Jason M.; Kasevich, Mark A.; Rajendran, Surjeet

    2016-11-01

    We describe an atom interferometric gravitational wave detector design that can operate in a resonant mode for increased sensitivity. By oscillating the positions of the atomic wave packets, this resonant detection mode allows for coherently enhanced, narrow-band sensitivity at target frequencies. The proposed detector is flexible and can be rapidly switched between broadband and narrow-band detection modes. For instance, a binary discovered in broadband mode can subsequently be studied further as the inspiral evolves by using a tailored narrow-band detector response. In addition to functioning like a lock-in amplifier for astrophysical events, the enhanced sensitivity of the resonant approach also opens up the possibility of searching for important cosmological signals, including the stochastic gravitational wave background produced by inflation. We give an example of detector parameters which would allow detection of inflationary gravitational waves down to ΩGW˜10-14 for a two-satellite space-based detector.

  6. A Wireless, Passive Load Cell based on Magnetoelastic Resonance

    PubMed Central

    Pereles, Brandon D.; Dienhart, Thomas; Sansom, Thadeus; Johnston, Kyle; Ong, Keat Ghee

    2012-01-01

    A wireless, battery-less load cell was fabricated based on the resonant frequency shift of a vibrating magnetoelastic strip when exposed to an AC magnetic field. Since the vibration of the magnetoelastic strip generated a secondary field, the resonance was remotely detected with a coil. When a load was applied to a small area on the surface of the magnetoelastic strip via a circular rod applicator, the resonant frequency and amplitude decreased due to the damping on its vibration. The force sensitivity of the load cell was controlled by changing the size of the force applicator and placing the applicator at different locations on the strip’s surface. Experimental results showed the force sensitivity increased with a larger applicator placing near the edge of the strip. The novelty of this load cell is not only its wireless passive nature, but also the controllability of the force sensitivity. PMID:22791938

  7. Experiment study of an electron cyclotron resonant ion source based on a tapered resonance cavity

    SciTech Connect

    Yang, Juan; Shi, Feng; Jin, Yizhou; Wang, Yunmin; Komurasaki, Kimiya

    2013-12-15

    Electron cyclotron resonant plasma is one type of magnetised plasma generated by continuous microwave energy. It has the property of high degree of ionization and large volume at low gas pressure, which makes it useful for space propulsion and material processing. This article presents the experiment study of the plasma properties and ion beam extraction from an electron cyclotron resonant ion source based on a tapered resonance cavity. Optical emission spectroscopy based on a simple collisional radiation model was used for plasma diagnosis. Experiment results show that, at microwave power setting ranging from 7.06 to 17.40 W and mass flow rate ranging from 1 to 10 sccm, argon gas can be ionized. Ion beam of 109.1 mA from the ion source can be extracted at microwave power of 30 W, mass flow rate of 10 sccm, and accel voltage of 800 V. The diagnosed plasma temperature and density are 2.4–5.2 eV and 2 × 10{sup 16}–4.8 × 10{sup 17} m{sup −3}, respectively.

  8. Microwave Photonics Systems Based on Whispering-gallery-mode Resonators

    PubMed Central

    Coillet, Aurélien; Henriet, Rémi; Phan Huy, Kien; Jacquot, Maxime; Furfaro, Luca; Balakireva, Irina; Larger, Laurent; Chembo, Yanne K.

    2013-01-01

    Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various areas of technology and applied science, such as aerospace and communication engineering, sensing, metrology, nonlinear photonics, and quantum optics. In this article, we present the principal techniques used in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators. First detailed in this article is the protocol for resonator polishing, which is based on a grind-and-polish technique close to the ones used to polish optical components such as lenses or telescope mirrors. Then, a white light interferometric profilometer measures surface roughness, which is a key parameter to characterize the quality of the polishing. In order to launch light in the resonator, a tapered silica fiber with diameter in the micrometer range is used. To reach such small diameters, we adopt the "flame-brushing" technique, using simultaneously computer-controlled motors to pull the fiber apart, and a blowtorch to heat the fiber area to be tapered. The resonator and the tapered fiber are later approached to one another to visualize the resonance signal of the whispering gallery modes using a wavelength-scanning laser. By increasing the optical power in the resonator, nonlinear phenomena are triggered until the formation of a Kerr optical frequency comb is observed with a spectrum made of equidistant spectral lines. These Kerr comb spectra have exceptional characteristics that are suitable for several applications in science and technology. We consider the application related to ultra-stable microwave frequency synthesis and demonstrate the generation of a Kerr comb with GHz intermodal frequency. PMID:23963358

  9. Microwave photonics systems based on whispering-gallery-mode resonators.

    PubMed

    Coillet, Aurélien; Henriet, Rémi; Phan Huy, Kien; Jacquot, Maxime; Furfaro, Luca; Balakireva, Irina; Larger, Laurent; Chembo, Yanne K

    2013-08-05

    Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various areas of technology and applied science, such as aerospace and communication engineering, sensing, metrology, nonlinear photonics, and quantum optics. In this article, we present the principal techniques used in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators. First detailed in this article is the protocol for resonator polishing, which is based on a grind-and-polish technique close to the ones used to polish optical components such as lenses or telescope mirrors. Then, a white light interferometric profilometer measures surface roughness, which is a key parameter to characterize the quality of the polishing. In order to launch light in the resonator, a tapered silica fiber with diameter in the micrometer range is used. To reach such small diameters, we adopt the "flame-brushing" technique, using simultaneously computer-controlled motors to pull the fiber apart, and a blowtorch to heat the fiber area to be tapered. The resonator and the tapered fiber are later approached to one another to visualize the resonance signal of the whispering gallery modes using a wavelength-scanning laser. By increasing the optical power in the resonator, nonlinear phenomena are triggered until the formation of a Kerr optical frequency comb is observed with a spectrum made of equidistant spectral lines. These Kerr comb spectra have exceptional characteristics that are suitable for several applications in science and technology. We consider the application related to ultra-stable microwave frequency synthesis and demonstrate the generation of a Kerr comb with GHz intermodal frequency.

  10. An Improved Label-Free Indirect Competitive SPR Immunosensor and Its Comparison with Conventional ELISA for Ractopamine Detection in Swine Urine

    PubMed Central

    Wang, Sai; Zhao, Shuai; Wei, Xiao; Zhang, Shan; Liu, Jiahui; Dong, Yiyang

    2017-01-01

    Ractopamine (RCT) is banned for use in animals in many countries, and it is urgent to develop efficient methods for specific and sensitive RCT detection. A label-free indirect competitive surface plasmon resonance (SPR) immunosensor was first developed with a primary antibody herein and then improved by a secondary antibody for the detection of RCT residue in swine urine. Meanwhile, a pre-incubation process of RCT and the primary antibody was performed to further improve the sensitivity. With all the key parameters optimized, the improved immunosenor can attain a linear range of 0.3–32 ng/mL and a limit of detection (LOD) of 0.09 ng/mL for RCT detection with high specificity. Furthermore, the improved label-free SPR immunosenor was compared thoroughly with a conventional enzyme-linked immunosorbent assay (ELISA). The SPR immunosensor showed advantages over the ELISA in terms of LOD, reagent consumption, analysis time, experiment automation, and so on. The SPR immunosensor can be used as potential method for real-time monitoring and screening of RCT residue in swine urine or other samples. In addition, the design using antibody pairs for biosensor development can be further referred to for other small molecule detection. PMID:28300766

  11. A capacitive ultrasonic transducer based on parametric resonance

    NASA Astrophysics Data System (ADS)

    Surappa, Sushruta; Satir, Sarp; Levent Degertekin, F.

    2017-07-01

    A capacitive ultrasonic transducer based on a parametric resonator structure is described and experimentally demonstrated. The transducer structure, which we call capacitive parametric ultrasonic transducer (CPUT), uses a parallel plate capacitor with a movable membrane as part of a degenerate parametric series RLC resonator circuit with a resonance frequency of fo. When the capacitor plate is driven with an incident harmonic ultrasonic wave at the pump frequency of 2fo with sufficient amplitude, the RLC circuit becomes unstable and ultrasonic energy can be efficiently converted to an electrical signal at fo frequency in the RLC circuit. An important characteristic of the CPUT is that unlike other electrostatic transducers, it does not require DC bias or permanent charging to be used as a receiver. We describe the operation of the CPUT using an analytical model and numerical simulations, which shows drive amplitude dependent operation regimes including parametric resonance when a certain threshold is exceeded. We verify these predictions by experiments with a micromachined membrane based capacitor structure in immersion where ultrasonic waves incident at 4.28 MHz parametrically drive a signal with significant amplitude in the 2.14 MHz RLC circuit. With its unique features, the CPUT can be particularly advantageous for applications such as wireless power transfer for biomedical implants and acoustic sensing.

  12. A capacitive ultrasonic transducer based on parametric resonance.

    PubMed

    Surappa, Sushruta; Satir, Sarp; Levent Degertekin, F

    2017-07-24

    A capacitive ultrasonic transducer based on a parametric resonator structure is described and experimentally demonstrated. The transducer structure, which we call capacitive parametric ultrasonic transducer (CPUT), uses a parallel plate capacitor with a movable membrane as part of a degenerate parametric series RLC resonator circuit with a resonance frequency of fo. When the capacitor plate is driven with an incident harmonic ultrasonic wave at the pump frequency of 2fo with sufficient amplitude, the RLC circuit becomes unstable and ultrasonic energy can be efficiently converted to an electrical signal at fo frequency in the RLC circuit. An important characteristic of the CPUT is that unlike other electrostatic transducers, it does not require DC bias or permanent charging to be used as a receiver. We describe the operation of the CPUT using an analytical model and numerical simulations, which shows drive amplitude dependent operation regimes including parametric resonance when a certain threshold is exceeded. We verify these predictions by experiments with a micromachined membrane based capacitor structure in immersion where ultrasonic waves incident at 4.28 MHz parametrically drive a signal with significant amplitude in the 2.14 MHz RLC circuit. With its unique features, the CPUT can be particularly advantageous for applications such as wireless power transfer for biomedical implants and acoustic sensing.

  13. Electrochemical immunosensor for ultrasensitive detection of microcystin-LR based on graphene-gold nanocomposite/functional conducting polymer/gold nanoparticle/ionic liquid composite film with electrodeposition.

    PubMed

    Ruiyi, Li; Qianfang, Xia; Zaijun, Li; Xiulan, Sun; Junkang, Liu

    2013-06-15

    The study developed an electrochemical immunosensor for ultrasensitive detection of microcystin-LR in water. Graphene oxide and chloroauric acid were alternately electrodeposited on the surface of glassy carbon electrode for 20 cycles to fabricate graphene-gold nanocomposite. The composite was characterized and its apparent heterogeneous electron transfer rate constant (37.28±0.16 cm s (-1)) was estimated by Laviron's model. To immobilize microcystin-LR antibody and improve the electrical conductivity, 2,5-di-(2-thienyl)-1-pyrrole-1-(p-benzoic acid) and chloroauric acid were electrodeposited on the modified electrode in sequence. The ionic liquid was then dropped on the electrode surface and finally microcystin-LR antibody was covalently connected to the conducting polymer film. Experiment showed the electrochemical technique offers control over reaction parameters and excellent repeatability. The graphene-gold nanocomposite and gold nanoparticles enhance electron transfer of Fe(CN)6(3-/4-) to the electrode. The ionic liquid, 1-isobutyl-3-methylimidazolium bis(trifluoromethane-sulfonyl)imide, improves stability of the antibody. The sensor displays good repeatability (RSD=1.2%), sensitive electrochemical response to microcystin-LR in the range of 1.0×10(-16)-8.0×10(-15)M and detection limit of 3.7×10(-17)M (S/N=3). The peak current change of the sensor after and before incubation with 2.0×10(-15)M of microcystin-LR can retain 95% over a 20-weeks storage period. Proposed method presents remarkable improvement of sensitivity, repeatability and stability when compared to present microcystin-LR sensors. It has been successfully applied to the microcystin-LR determination in water samples with a spiked recovery in the range of 96.3-105.8%. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Detection of small molecules with a flow immunosensor

    NASA Technical Reports Server (NTRS)

    Kusterbeck, Anne W.; Ligler, Frances S.

    1991-01-01

    We describe the development of an easy-to-use sensor with widespread applications for detecting small molecules. The flow immunosensor can analyze discrete samples in under one minute or continuously monitor a flowing stream for the presence of specific analytes. This detection system is extremely specific, and achieves a level of sensitivity which meets or exceeds the detection limits reported for rival assays. Because the system is also compact, transportable, and automated, it has the potential to impact diverse areas. For example, the flow immunosensor has successfully detected drugs of abuse and explosives, and may well address many of the needs of the environmental community with respect to continuous monitoring for pollutants. Efforts are underway to engineer a portable device in the field.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Resonant-cavity based monolithic white light-emitting diode

    NASA Astrophysics Data System (ADS)

    Huang, Lirong; Huang, Dexiu; Wen, Feng

    2007-11-01

    We propose a new scheme of resonant-cavity (RC) based monolithic white LED, it relaxes the hard requirement of high internal quantum efficiency of yellow multi-quantum (MQW) and offers an easy way to obtain high luminous efficacy white light emission. In the proposed white LED, the blue MQW and yellow MQW active layer are embedded in a resonant-cavity defined by the bottom distributed Bragg reflector(DBR) and top DBR. For a optimal design of RC-based white LED, the extraction efficiency for yellow light is enhanced, while that for blue light is suppressed, thus intensity ratio of yellow light in the emitting light is increased, which not only helps to obtain white emission in spite of the low internal quantum efficiency of yellow light, but also doubles luminous efficacy. The color coordinates and luminous flux of the emitting light from RC-based white LED are calculated and the performance dependence on directionality is investigated.

  17. Electrochemical Immunosensors for Detection of Cancer Protein Biomarkers

    PubMed Central

    Chikkaveeraiah, Bhaskara V.; Bhirde, Ashwinkumar; Morgan, Nicole Y.; Eden, Henry S.

    2012-01-01

    Bioanalytical methods have experienced unprecedented growth in recent years, driven in large part by the need for faster, more sensitive, more portable (“point of care”) systems to detect protein biomarkers for clinical diagnosis. Electrochemical detection strategies, used in conjunction with immunosensors, offer advantages, because they are fast, simple, and low cost. Recent developments in electrochemical immunosensors have significantly improved the sensitivity needed to detect low concentrations of biomarkers present in early stages of cancer. Moreover, the coupling of electrochemical devices with nanomaterials, such as gold nanoparticles, carbon nanotubes, magnetic particles, and quantum dots, offers multiplexing capability for simultaneous measurements of multiple cancer biomarkers. This review will discuss recent advances in the development of electrochemical immunosensors for the next-generation of cancer diagnostics, with an emphasis on opportunities for further improvement in cancer diagnostics and treatment monitoring. Details will be given for strategies to increase sensitivity through multi-label amplification, coupled with high densities of capture molecules on sensor surfaces. Such sensors are capable of detecting a wide range of protein quantities, from ng to fg (depending on the protein biomarkers of interest), in a single sample. PMID:22835068

  18. Investigation of a near-infrared fiber optic immunosensor

    NASA Astrophysics Data System (ADS)

    Daneshvar, Maryam I.; Casay, Guillermo A.; Lipowska, Malgorzata; Patonay, Gabor; Strekowski, Lucjan

    1994-03-01

    The designs of NIR optical fiber immunosensors for the detection of biomolecules are discussed. The use of fiber optics combined with laser-excited fluorescence detection ((lambda) max equals 780 nm) and immunochemical techniques has provided the essential components for developing simpler and more practical, sensitive and selective immunosensors. The antibody is immobilized on the distal end of a surface-activated polymethyl methylacrylate sensor. As the probe is placed in different concentrations of antigenic substance, the antibody reacts with its corresponding antigen through sandwich and/or competitive immunoassays. The concentrations varied from 10 - 100 ng/ml. The near-infrared dye labeled antigen - antibody complex is excited and the emitted fluorescence is collected with a silicon photodiode detector equipped with an 820-nm bandpass filter. In order to determine various factors influencing the immunosensor's performance, the fluorescence intensity responses are obtained under a variety of conditions. The sensor response depending on the type of surface-activating reagent, surface activation period, incubation time, and other measurement conditions also are discussed.

  19. Image-based tracking of optically detunable parallel resonant circuits.

    PubMed

    Eggers, Holger; Weiss, Steffen; Boernert, Peter; Boesiger, Peter

    2003-06-01

    In this work strategies for the robust localization of parallel resonant circuits are investigated. These strategies are based on the subtraction of two images, which ideally differ in signal intensity at the positions of the devices only. To modulate their signal amplification, and thereby generate the local variations, the parallel resonant circuits are alternately detuned and retuned during the acquisition. The integration of photodiodes into the devices permits their fast optical switching. Radial and spiral imaging sequences are modified to provide the data for the two images in addition to those for a conventional image in the same acquisition time. The strategies were evaluated by phantom experiments with stationary and moving catheter-borne devices. In particular, rapid detuning and retuning during the sampling of single profiles is shown to lead to a robust localization. Moreover, this strategy eliminates most of the drawbacks usually associated with image-based tracking, such as low temporal resolution. Image-based tracking may thus become a competitive (if not superior) alternative to projection-based tracking of parallel resonant circuits.

  20. Dependence of the signal amplification potential of colloidal gold nanoparticles on resonance wavelength in surface plasmon resonance-based detection

    PubMed Central

    Fu, Elain; Ramsey, Stephen A.; Yager, Paul

    2008-01-01

    We demonstrate the resonance wavelength-dependent signal of colloidal gold nanoparticles adsorbed to a planar gold surface in surface plasmon resonance (SPR)-based detection. Experimental measurements of the SPR signal as a function of particle surface coverage are presented for three different resonance wavelengths. The SPR signal due to the colloidal gold nanoparticles varies across the resonance wavelengths of 650 nm, 770 nm, and 920 nm. The experimental SPR curves show good agreement with the results of a Lorentz absorbance model at the lower particle surface coverages investigated. The results demonstrate an almost 2-fold signal difference for a subset of the experimental conditions explored. PMID:17765071

  1. Experimental investigation of energy localization in line-defect resonator based on silicon locally resonant phononic crystal

    NASA Astrophysics Data System (ADS)

    Jiang, Wanli; Feng, Duan; Xu, Dehui; Xiong, Bin; Wang, Yuelin

    2016-10-01

    In this paper, energy localization in line-defect resonator based on locally resonant phononic crystal (PnC) is experimentally studied. The defected resonator is realized by creating line defects on a two-dimension (2-D) silicon PnC. The silicon resonator was fabricated by micro machining process and tested by a combination of the fluid coupling method and Laser Doppler Vibrometer (LDV). Acoustic waves with frequency range from 7.19 MHz to 7.50 MHz are trapped in the cavity, and the corresponding resonant modes are observed in-situ. The measured quality (Q) factor of the resonator, which is 427 at its resonant frequency of 7.3 MHz, is smaller than the simulated ones (666 and 5135). The experimental results agree well with the simulation results that frequencies of the trapped acoustic waves of are mostly in the range of the phononic bandgaps. The locally resonant based PnC resonator in paper with 17 dB magnitude amplification, which is normalized with respect to the transmission of a freestanding silicon slab in the same frequency range, has great potential in energy harvesting or sound concentration.

  2. Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials.

    PubMed

    Liu, Chao; Schauff, Joseph; Lee, Seokhyeong; Cho, Jeong-Hyun

    2017-03-23

    Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR is not affected by environmental characteristics such as the temperature and pressure surrounding the resonator. Electromagnetic radiation in THz frequencies is biocompatible, which is a critical condition especially for the application of the biomolecular sensing. However, the quality factor (Q-factor) and frequency responses of traditional thin-film based split ring resonator (SRR) MMs are very low, which limits their sensitivities and selectivity as sensors. In this work, novel nanopillar-based SRR MMs, utilizing displacement current, are designed to enhance the Q-factor up to 450, which is around 45 times higher than that of traditional thin-film-based MMs. In addition to the enhanced Q-factor, the nanopillar-based MMs induce a larger frequency shifts (