What is it about?

Magnetic nanoparticles (MNPs) have been adapted for many applications, e.g., bioassays for the detection of biomarkers such as antibodies, by controlled engineering of specific surface properties. Specific measurement of such binding states is of high interest but currently limited to highly sensitive techniques such as ELISA or flow cytometry, which are relatively inflexible, difficult to handle, expensive and time-consuming. Here we report a method named COMPASS (Critical-Offset-Magnetic-Particle-SpectroScopy), which is based on a critical offset magnetic field, enabling sensitive detection to minimal changes in mobility of MNP ensembles, e.g., resulting from SARS-CoV-2 antibodies binding to the S antigen on the surface of functionalized MNPs. With a sensitivity of 0.33 fmole/50 µl (≙7 pM) for SARS-CoV-2-S1 antibodies, measured with a low-cost portable COMPASS device, the proposed technique is competitive with respect to sensitivity while providing flexibility, robustness, and a measurement time of seconds per sample. In addition, initial results with blood serum demonstrate high specificity.

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Why is it important?

'real' rapid testing method to investigate effective viscosity changes in fluids ** Why it is cool...? >> You now have a robust, cheap and easy-to-use technology, which is able to measure, e.g., tiny changes in the diameter of nanoparticles... ** ...and what can I do with that? Quite a lot of different things...for example building highly sensitive bioassays for detecting antibodies, antigens or other ligands, which link on the surface of the specific engineered nanoparticles. With that, we are able to detect specific antibodies with a sensitivity competitive with ELISA tests...but much much faster. In just a few seconds, instead of hours, the results are available...


future way for highly sensitive and flexible bioassays

Patrick Vogel
University of Würzburg

Read the Original

This page is a summary of: Critical Offset Magnetic PArticle SpectroScopy for rapid and highly sensitive medical point-of-care diagnostics, Nature Communications, November 2022, Springer Science + Business Media, DOI: 10.1038/s41467-022-34941-y.
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