Homogeneous differential magnetic assay
Journal article, 2019

Assays are widely used for detection of various targets, including pathogens, drugs, and toxins. Homogeneous assays are promising for the realization of point-of-care diagnostics as they do not require separation, immobilization, or washing steps. For low concentrations of target molecules, the speed and sensitivity of homogeneous assays have hitherto been limited by slow binding kinetics, time-consuming amplification steps, and the presence of a high background signal. Here, we present a homogeneous differential magnetic assay that utilizes a differential magnetic readout that eliminates previous limitations of homogeneous assays. The assay uses a gradiometer sensor configuration combined with precise microfluidic sample handling. This enables simultaneous differential measurement of a positive test sample containing a synthesized Vibrio cholerae target and a negative control sample, which reduces the background signal and increases the readout speed. Very low concentrations of targets down to femtomolar levels are thus detectable without any additional amplification of the number of targets. Our homogeneous differential magnetic assay method opens new possibilities for rapid and highly sensitive diagnostics at the point of care.

homogeneous differential magnetic assay


Brownian relaxation

magnetic nanoparticles

rolling circle amplification


Sobhan Sepehri

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

Teresa Zardán Gómez De La Torre

Uppsala University

Justin Schneiderman

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

Jakob Blomgren

RISE Research Institutes of Sweden

Aldo Jesorka

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Christer Johansson

Chalmers, Microtechnology and Nanoscience (MC2)

Mats Nilsson

Science for Life Laboratory (SciLifeLab)

Jan Albert

Karolinska University Hospital

Karolinska Institutet

Maria Strømme

Uppsala University

Dag Winkler

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

Alexei Kalaboukhov

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics

ACS Sensors

23793694 (eISSN)

Vol. 4 9 2381-2388

Point-of care Influenza Diagnostics FLU-ID

Swedish Foundation for Strategic Research (SSF) (SBE13-0125), 2021-01-01 -- 2021-03-31.

Swedish Foundation for Strategic Research (SSF) (SBE13-0125), 2014-06-01 -- 2020-12-31.

Areas of Advance

Nanoscience and Nanotechnology

Subject Categories

Analytical Chemistry

Medical Equipment Engineering

Other Physics Topics

Biomedical Laboratory Science/Technology

Nano Technology

Other Industrial Biotechnology

Driving Forces

Innovation and entrepreneurship


Nanofabrication Laboratory



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1/3/2024 9