Sánchez, B.; Vega, D.; Rodriguez, A.; Bragos, R.; Marco, M.P.; Valera, E. Sensors and actuators B. Chemical Vol. 203, p. 444-451 DOI: 10.1016/j.snb.2014.06.139 Date of publication: 2014-11-01 Journal article
A magnetic interdigitated microelectrode (m-ID mu E) has been developed, characterized and evaluated. In order to demonstrate the potential use of these electrodes in the biosensors field, impedimetric measurements of bovine serum albumin (BSA) biofunctionalized magnetic mu-particles (BSAMP) were performed. Thanks to their magnetic capabilities and to the use of magnetic mu-particles, the developed electrodes were successfully regenerated and could be reused several times. The classical stepped-sine impedance spectroscopy (IS) technique and the state-of-art frequency response analyzer (FRA) multisine IS method based on the local polynomial method (LPM) were used as measurement techniques. The significant reduction of measuring time and accuracy of the multisine IS LPM-based technique reveals a promising performance for fast and accurate real-time on-line screening applications. (C) 2014 Elsevier B.V. All rights reserved.
The potential of a conductimetric immunosensor to detect residual amounts of atrazine in a complexv matrix, such as red wine, is evaluated. The immunosensor presented is based on interdigitated μ-electrodes (IDμEs), immunoreagents specifically developed to detect atrazine, and antibodies labelled with gold nanoparticles. Due to the amplification of the conductive signal, produced by the presence of the gold particles, atrazine can be detected using simple and inexpensive direct current (DC) measurements.
Then, sensors response is related to the atrazine concentration in the sample. Likewise, the presence of gold particles generates an increase in the intensity of the electric field between the electrodes. The time for assay completion, for 48 samples, was 5 h. Nevertheless, during the first hour (devoted to the incubation
assays), the number of samples could be increased without prejudice the assay duration. Sensor responses obtained using red wine samples are compared with results obtained using buffer solutions. As a consequence, the strong matrix effect related to red wine samples has been identified as a non-specific increase of the current intensity through the device.
The limits of detection (LODs) obtained are far below the Maximum Residue Level (50 μg kg-1) established by EU for residues of atrazine as herbicide in the wine grapes and other foodstuff products. This opens the door to commercial sensors of simple manipulation, transportable and economics.
The present paper describes a simple and low-cost method for the fabrication of mechanically flexible interdigitated μ-electrodes (FIDμEs) and its application as immunosensor.
FIDμEs consist of two coplanar non-passivated interdigitated metallic μ-electrodes supported on a flexible transparent substrate, polyethylene naphthalate (PEN). Bioreagents deposition on PEN substrates becomes possible by depositing SiO2 on the electrodes surface (fingers and inter-digits space).
These FIDμEs were successfully applied for the development of a selective conductimetric immunosensor for the quantification of atrazine residues. The immunosensor has been demonstrated for detection of small amounts of atrazine, thanks to the use of immunoreagents specifically developed to detect this pesticide.
The detection method applied is based on the use of antibodies labelled with gold nanoparticles. The presence of these particles amplifies the conductive signal; hence the immunosensor response was quantified using simple and inexpensive DC measurements.
Immunochemical detection of the concentrations of atrazine is achieved by a competitive reaction which occurs before the inclusion of the labelled antibodies.
The immunosensor shows limits of detection in the order of 2–3 μg L−1, far below the maximum residue level (50 μg kg−1) established by EU for residues of atrazine as herbicide in the wine grapes and other foodstuff products.
This contribution describes the development of an impedimetric immunosensor for atrazine detection. This
immunosensor is based on the use of interdigitated metallic
μ-electrodes (IDμEs) The method described in this work does not use any redox mediator and relies on the direct detection of
immunochemical competitive reaction between the pesticide and
a haptenized-protein immobilized on interdigitated
μ-electrodes for the specific antibody.
The immunoreagents used were specifically developed to detect atrazine. The immunochemical detection of this pesticide is achieved without using any label. The immunosensor shows a limit of detection of 8.34±1.37 μg L-1, witch is lower than the Maximun Residue Level (MRL) (50μg L-1)established by EU (European Union)for residues of atrazine as herbicide in the wine grapes and other foodstuff products.
Two novel immunosensors, one impedimetric and other one conductimetric, for atrazine detection in red wine samples have been developed. Impedimetric immunosensor is based on an array of interdigitated μ-
electrodes (IDμEs) and bioreagents specifically developed to detect this pesticide. Conductimetric immunosensor incorporates additionally gold nanoparticles. Bioreagents were covalently immobilized on the surface of the electrodes (interdigital space). In both cases the biochemical determination of atrazine is
possible without any redox mediator. For the case of the impedimetric immunosensor, the detection method is based on impedimetric measurements (in a wide range of frequencies), whereas in the case of the
conductimetric immunosensor the detection method is based on conductimetric measurements (DC measurements).The potential of the impedimetric immunosensor to analyze atrazine in complex sample matrices, such as red wine, have been evaluated. This immunosensor can detect atrazine with limits of detection in the order sub-ppb, far below the maximum residue level (MRL) (50 μg L−1) established by European Union (EU) for residues of this herbicide in the wine grapes.
Valera, E.; Ramón-Azcon, J.; Sánchez-Baeza, F.; Marco, M.P.; Rodriguez, A. Congreso Español de Ingeniería de Alimentos y Congreso Iberoamericano sobre Seguridad Alimentaria (CESIA-CIBSA) p. 1-6 Presentation's date: 2008-11 Presentation of work at congresses
En este trabajo describimos un immunosensor impedimétrico para la detección de
pesticidas. Para demostrar dicho sensor hemos utilizado atrazina, como pesticida de test. Este sensor está basado en el uso de μ-electrodos interdigitados así como en reactivos específicamente desarrollados para la detección de este pesticida. Los anticuerpos utilizados no incluyen ningún tipo de etiqueta. Así mismo, el sensor no
incluye ningún tipo de par redox que amplifique la señal. La detección immunoquímica de atrazina se alcanza mediante una reacción competitiva entre el antígeno tapizado y el pesticida por una pequeña cantidad de anticuerpo. Los cambios en la impedancia producidos por la inclusión de los bioreactivos son interpretados utilizando un circuito equivalente, el
cual representa el sistema de manera fiable. La detección se monitoriza a partir de medidas impedimétricas diferenciales en un amplio espectro de frecuencia. El immunosensor muestra límites de detección en el rango de pocos ppb's, lo cual está muy
por debajo del Maximum Residue Level (MRL) (50 μg L-1) establecido por la Unión Europea
para los residuos de atrazina en uvas de vino así como en otros productos alimenticios.
Aunque en este trabajo el immunosensor se ha demostrado para la atrazina, otros pesticidas
podrían detectarse mediante este método siempre que se utilicen los reactivos adecuados.
Urbiztondo, M.; Valera, E.; Todorov, T.; Alcubilla, R.; Irusta, S.; Pina, M.; Rodriguez, A.; Santamaria, J. Journal of catalysis Vol. 250, num. 1, p. 190-194 Date of publication: 2007-08 Journal article