scholarly journals Glyphosate Determination by Coupling an Immuno-Magnetic Assay with Electrochemical Sensors

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2965 ◽  
Author(s):  
Francesca Bettazzi ◽  
Aline Romero Natale ◽  
Eduardo Torres ◽  
Ilaria Palchetti
Keyword(s):  
Magnetic Particles ◽  
Electrochemical Sensors ◽  
Electrochemical Cell ◽  
Electrochemical Immunoassay ◽  
Competitive Immunoassay ◽  
Quantification Limit ◽  
Intensive Use ◽  
Current Value ◽  
Global Contamination ◽  
Enzymatic Product

Glyphosate (N-(phosphonomethyl)glycine) is the most frequently used broad-spectrum herbicide worldwide. Its mechanism of action is based on the inhibition of an enzyme that is essential to plant growth. Its intensive use has caused global contamination to occur, which has not only affected the ecosystems, but even food and other objects of common use. Thus, there is a pronounced need for developing analytical methods for glyphosate determination in different matrices. Here, an electrochemical competitive immunoassay, based on the use of antibody-modified magnetic particles, has been developed. Tetramethylbenzidine (TMB) has been used as an enzymatic substrate. The extent of the affinity reaction has been achieved by monitoring the current value, due to the reduction of the enzymatic product. A disposable screen-printed electrochemical cell has been used. The calibration curve has been recorded in the 0–10,000 ng/L concentration range, with a detection limit of 5 ng/L and quantification limit of 30 ng/L. The electrochemical immunoassay has also been applied to the analysis of spiked beer samples.

Miniature Multi-electrode Electrochemical Cell in LTCC

2007 ◽  
Vol 4 (1) ◽  
pp. 31-36
Author(s):  
John Youngsman ◽  
Brian Marx ◽  
Scott Wolter ◽  
Jeff Glass ◽  
Amy Moll
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Sensors ◽  
Electrochemical Cell ◽  
Sea Water ◽  
Electrochemical Impedance ◽  
Chemical Species ◽  
Analytical Instruments ◽  
Toxic Gases ◽  
Significant Research ◽  
Eis Analysis

The miniaturization of analytical instruments and packaging of novel sensors is an area that has attracted significant research interest and offers many opportunities for product commercialization. Electrochemical sensors have been used to detect a wide variety of compounds including toxic gases. A miniature electrochemical cell has been designed, constructed, and tested for functionality. The cell will be used in identifying and selecting chemical species in solutions. The cell was constructed of low temperature co-fired ceramic (LTCC) material using gold for the electrodes. Tests performed in sulfuric acid and sea water solutions show that the cell is functioning based on cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analysis. Miniaturization allows the cell to be deployed as a sensor in many different environments.

Rapid solid-phase immunoassay for 6-keto prostaglandin F1 alpha on microplates

1990 ◽  
Vol 36 (3) ◽  
pp. 509-514 ◽  
Author(s):  
W Schramm ◽  
R H Smith ◽  
T M Jackson ◽  
P A Craig ◽  
H E Grates ◽  
...  
Keyword(s):  
Magnetic Particles ◽  
Culture Medium ◽  
Solid Phase ◽  
Plasma Samples ◽  
Competitive Immunoassay ◽  
Immobilized Antibodies ◽  
Solid Phase Immunoassay ◽  
Hands On ◽  
Solid Phase Assay ◽  
Optimal Incubation

Abstract We describe, for the measurement of 6-keto prostaglandin F1 alpha in biological media, a solid-phase immunoassay with immobilized antibodies that requires a total processing time of less than 2 h with hands-on time less than 30 min for 40 samples. The method combines the convenience of the microplate format with the sensitivity of radiolabeled prostaglandin derivatives as tracers in a competitive immunoassay. The intra- and interassay variations at 50% displacement of the radiolabeled prostaglandin derivative as tracer were 9.0% and 11.8%, respectively. At 50% displacement of the radiolabeled tracer, the sensitivity is about 20 pg per well. Optimal incubation time is between 60 and 90 min. Nonspecific binding was less than 1% if about 8 pg of tracer (approximately 25,000 counts/min per well) was used. Inhibition curves of samples in different dilutions were parallel to standard curves. The variation of bound radiolabeled prostaglandin derivative within the wells of one microplate (n = 96) was less than 3%. Human plasma samples and medium from tissue culture assayed for 6-keto prostaglandin F1 alpha correlated well with results obtained with a solid-phase assay based on use of magnetic particles (r = 0.99, n = 24 for culture-medium samples; r = 0.99; n = 26 for plasma samples.

Developing enhanced magnetoimmunosensors based on low-cost screen-printed electrode devices

2016 ◽  
Vol 35 (2) ◽  
pp. 53-85 ◽  
Author(s):  
Zorione Herrasti ◽  
Erica de la Serna ◽  
Gisela Ruiz-Vega ◽  
Eva Baldrich
Keyword(s):  
High Performance ◽  
Magnetic Particles ◽  
Electrochemical Cell ◽  
Point Of Care ◽  
Low Cost ◽  
Screen Printed Electrode ◽  
Spectrophotometric Detection ◽  
Complex Sample ◽  
Different Types ◽  
Screen Printed

AbstractElectrochemical magnetoimmunosensors combine a number of issues that guarantee extremely high performance and also compatibility with the study of complex sample matrices. First, analyte immunocapture exploits the high affinity and specificity of antibodies. Second, magnetic particles (MP) provide faster and more efficient immunocapture than binding on two-dimensional structures, separation from nontarget sample components, and concentration of the target analyte. Finally, electrochemical detection supplies sensitivity and fast signal generation using robust and potentially miniaturized measurement equipment and transducers. On the contrary, MP handling is slightly more complex for end-users and more difficult to integrate in point-of-care devices than the manipulation of a classical biosensor. Attempts have been made to automate immunomagnetic binding, and the first robotized systems and platforms for the fluorescent and spectrophotometric detection of magnetoimmunoassays have already reached the market. Among the different types of electrodes available, screen-printed electrodes (SPE) stand out because of their low production cost and yet acceptable performance and interdevice reproducibility, which make them an excellent choice for analytical applications. In addition, each SPE entails a whole electrochemical cell stamped on a planar physical substrate, which makes it possible detection in small volumes and is especially favorable for the magnetic confinement of MP and the integration of microfluidic structures. In this article, we discuss the advantages obtained by using SPE and MP for the production of electrochemical magnetoimmunosensors and the clues for the successful development of such devices. We then revise some of the most outstanding works published in the literature.

A magnetic super lattice

1987 ◽  
Vol 45 ◽  
pp. 360-361 ◽  
Author(s):  
M.D. Bentzon ◽  
J. v. Wonterghem ◽  
A. Thölén
Keyword(s):  
Thermal Decomposition ◽  
Oleic Acid ◽  
Magnetic Fluid ◽  
Magnetic Particles ◽  
Carbon Film ◽  
Thick Layer ◽  
Amorphous Iron ◽  
Super Lattice ◽  
Carrier Liquid ◽  
Median Diameter

We report on the oxidation of a magnetic fluid. The oxidation results in magnetic super lattice crystals. The “atoms” are hematite (α-Fe2O3) particles with a diameter ø = 6.9 nm and they are covered with a 1-2 nm thick layer of surfactant molecules.Magnetic fluids are homogeneous suspensions of small magnetic particles in a carrier liquid. To prevent agglomeration, the particles are coated with surfactant molecules. The magnetic fluid studied in this work was produced by thermal decomposition of Fe(CO)5 in Declin (carrier liquid) in the presence of oleic acid (surfactant). The magnetic particles consist of an amorphous iron-carbon alloy. For TEM investigation a droplet of the fluid was added to benzine and a carbon film on a copper net was immersed. When exposed to air the sample starts burning. The oxidation and electron irradiation transform the magnetic particles into hematite (α-Fe2O3) particles with a median diameter ø = 6.9 nm.

Electrochemical cell

1998 ◽  
Vol 70 (1) ◽  
pp. 167
Author(s):  
J Coetzer
Keyword(s):  
Electrochemical Cell

EFFECT OF APPLICATION OF FIELDS ON THE DOMAIN STRUCTURE IN SMALL REGULARLY SHAPED MAGNETIC PARTICLES

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-1817-C8-1818 ◽  
Author(s):  
S. McVitie ◽  
J. N. Chapman ◽  
S. J. Hefferman ◽  
W. A. P. Nicholson
Keyword(s):  
Domain Structure ◽  
Magnetic Particles

Analysis of magneto rheological elastomers for energy harvesting systems

2020 ◽  
Vol 64 (1-4) ◽  
pp. 439-446
Author(s):  
Gildas Diguet ◽  
Gael Sebald ◽  
Masami Nakano ◽  
Mickaël Lallart ◽  
Jean-Yves Cavaillé
Keyword(s):  
Magnetic Field ◽  
Energy Harvesting ◽  
Shear Strain ◽  
Magnetic Induction ◽  
Magnetic Particles ◽  
Homogeneous Magnetic Field ◽  
Electrical Signal ◽  
Harvesting Systems ◽  
Dc Bias ◽  
Magneto Rheological

Magneto Rheological Elastomers (MREs) are composite materials based on an elastomer filled by magnetic particles. Anisotropic MRE can be easily manufactured by curing the material under homogeneous magnetic field which creates column of particles. The magnetic and elastic properties are actually coupled making these MREs suitable for energy conversion. From these remarkable properties, an energy harvesting device is considered through the application of a DC bias magnetic induction on two MREs as a metal piece is applying an AC shear strain on them. Such strain therefore changes the permeabilities of the elastomers, hence generating an AC magnetic induction which can be converted into AC electrical signal with the help of a coil. The device is simulated with a Finite Element Method software to examine the effect of the MRE parameters, the DC bias magnetic induction and applied shear strain (amplitude and frequency) on the resulting electrical signal.

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