A SQUID measurement system for immunoassays

Matz, H.; Drung, D.; Hartwig, Stefan; Gross, Hermann; Kötitz, R.; Müller, Wolfgang; Vass, A.; Trahms, Lutz

doi:10.1016/s0964-1807(99)00014-9

Cited by 70 publications

(42 citation statements)

References 4 publications

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“…The stray field of magnetic markers is always present as long as they stay magnetized by an external magnetic field [12]. So, a number of MEMS magnetic biosensors have been reported in literatures including measurements of magnetic permeability [13], magneto-resistive sensors [14], spin-valves [15], Hall sensor [16] and giant magneto-impedance based sensors [17], superconducting quantum interference devices (SQUIDs) [18].…”

Section: Introductionmentioning

confidence: 99%

Sandwich immunoassay for the prostate specific antigen using a micro-fluxgate and magnetic bead labels

et al. 2016

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We describe a micro fluxgate based device with rectangular magnetic core for the determination of prostate specific antigen (PSA) labeled with Dynabeads. A sandwich immunoassay was employed where PSA is captured on a gold film modified with a self-assembled monolayer of antibody. The secondary antibody is labeled with Dynabeads. By applying a DC magnetic fields in the range of 460 to 700 μT, PSA can be detected with detection limit as low as 0.1 ng mL −1 . This micro fluxgate-based assay offers the advantages of miniaturization, simple and conveniently manipulation, reusability and stability. In our perception, it offers a viable approach towards clinical determination of PSA or other biomarkers.

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Section: Introductionmentioning

confidence: 99%

Sandwich immunoassay for the prostate specific antigen using a micro-fluxgate and magnetic bead labels

et al. 2016

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“…Therefore, some interesting transduction methods in magnetic biosensing use magnetic remanence and/or relaxation [173,174,175,176], mixed excitation frequency response [177,178], cantilever movements (e.g. force amplified biological sensor, FABS) [179], inductance [180,181], induced current [182] or magnetoresistance, such as giant magnetoresistance (GMR) [183,184,185,186].…”

Section: Magnetic Biosensorsmentioning

confidence: 99%

Electrochemical Biosensors - Sensor Principles and Architectures

Grieshaber

MacKenzie

Vörös

et al. 2008

Sensors

819

636

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

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“…These commercially available particles are usually 100 nm to 1 m in diameter and comprise a superparamagnetic core surrounded by a polymer shell (e.g., starch or polyvinyl alcohol) suitable for additional functionalization. The superparamagnetic core allows the direct detection and quantification of the particles using a variety of methods (28)(29)(30)(31)(32)(33).…”

Section: Potato Virus X (Pvx) and Tobacco Mosaic Virus (Tmv)mentioning

confidence: 99%

Simple and Portable Magnetic Immunoassay for Rapid Detection and Sensitive Quantification of Plant Viruses

Rettcher

Jungk

Kühn

et al. 2015

Appl Environ Microbiol

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c Plant pathogens cause major economic losses in the agricultural industry because late detection delays the implementation of measures that can prevent their dissemination. Sensitive and robust procedures for the rapid detection of plant pathogens are therefore required to reduce yield losses and the use of expensive, environmentally damaging chemicals. Here we describe a simple and portable system for the rapid detection of viral pathogens in infected plants based on immunofiltration, subsequent magnetic detection, and the quantification of magnetically labeled virus particles. Grapevine fanleaf virus (GFLV) was chosen as a model pathogen. Monoclonal antibodies recognizing the GFLV capsid protein were immobilized onto immunofiltration columns, and the same antibodies were linked to magnetic nanoparticles. GFLV was quantified by immunofiltration with magnetic labeling in a double-antibody sandwich configuration. A magnetic frequency mixing technique, in which a two-frequency magnetic excitation field was used to induce a sum frequency signal in the resonant detection coil, corresponding to the virus concentration within the immunofiltration column, was used for high-sensitivity quantification. We were able to measure GFLV concentrations in the range of 6 ng/ml to 20 g/ml in less than 30 min. The magnetic immunoassay could also be adapted to detect other plant viruses, including Potato virus X and Tobacco mosaic virus, with detection limits of 2 to 60 ng/ml.

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A SQUID measurement system for immunoassays

Cited by 70 publications

References 4 publications

Sandwich immunoassay for the prostate specific antigen using a micro-fluxgate and magnetic bead labels

Sandwich immunoassay for the prostate specific antigen using a micro-fluxgate and magnetic bead labels

Electrochemical Biosensors - Sensor Principles and Architectures

Simple and Portable Magnetic Immunoassay for Rapid Detection and Sensitive Quantification of Plant Viruses

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