Tracking the Growth of Superparamagnetic Nanoparticles with an In-Situ Magnetic Particle Spectrometer (INSPECT)

Malhotra, Ankit; Gladiss, Anselm von; Behrends, André; Friedrich, Thomas; Neumann, Alexander; Buzug, Thorsten M.; Lüdtke‐Buzug, Kerstin

doi:10.1038/s41598-019-46882-6

Cited by 15 publications

(8 citation statements)

References 49 publications

(41 reference statements)

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“…The advantage of this method is the direct access to particle parameters, which are of high interest for understanding the complex dynamics of MNP ensembles. Furthermore, fast and easy access to these parameters allows a robust MNP characterization during synthetization and hence gives immediate feedback for improving the quality of magnetic particles, e.g., for medical applications or environmental treatment 23 , 24 . Many applications in different fields of research are conceivable, and COMPASS could pave the way for their realization.…”

Section: Discussionmentioning

confidence: 99%

Critical Offset Magnetic PArticle SpectroScopy for rapid and highly sensitive medical point-of-care diagnostics

et al. 2022

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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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Section: Discussionmentioning

confidence: 99%

Critical Offset Magnetic PArticle SpectroScopy for rapid and highly sensitive medical point-of-care diagnostics

et al. 2022

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“…The advantage of this method is the direct access to particle parameters, which are of high interest for understanding the complex dynamics of MNP ensembles. Furthermore, fast and easy access to these parameters allows a robust MNP characterization during synthetization and hence gives immediate feedback of improving the quality of magnetic particles, e.g., for medical applications or environmental treatment [21,22].…”

Section: Mobile Compass Devicementioning

confidence: 99%

COMPASS – rapid and highly sensitive medical point-of-care diagnostic

Vogel

Rückert

Friedrich

et al. 2022

Preprint

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In the last decade Magnetic nanoparticles (MNPs) have gained an enormous interest in specialized areas such as medicine, cancer theranostics, biosensing, catalysis, agriculture, and the environmental protection. By controlled engineering of specific surface properties, named functionalization, MNPs are gaining special features for desired applications, e.g., bioassays for the detection of biomolecules or biomarkers such as antibodies. The characterization as well as a highly specific measurement of such binding states is of high interest and limited to highly sensitive techniques such as ELISA (Enzyme-linked Immunosorbent Assay) or flow cytometry, which are relatively inflexible, difficult to handle, expensive and time-consuming. Novel upcoming methods, such as ACS (AC susceptometry) or MPS (Magnetic Particle Spectroscopy), exploit the magnetization response of functionalized MNP ensembles to assess specific information about the MNP mobility within their environment as well as the conjugations of chemical or biological compounds on their surface. Both methods have shown promising results reaching similar sensitivities within short measurement times but showing difficulties in data interpretation. Here, we report a novel method, COMPASS (Critical Offset Magnetic PArticle SpectroScopy), which is based on a critical offset magnetic field of MNPs, which enables 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 validated sensitivity of 0.85 fmole/50 µl sample volume ( ≙ 33 pM) SARS-CoV-2-S1 antibodies, measured with a low-cost portable COMPASS device, the proposed technique is not only competitive with the sensitivity of commonly used ELISA or flow cytometry methods but provides more flexibility, robustness and rapid measurement withinwell below a minute per sample, including sample conjugation, mixing and incubation times. The underlying physical effect is based on an offset magnetic field induced suppression of a higher harmonic in the nonlinear magnetization response of the MNP to a time varying magnetic field resulting in a highly sensitive response of the signal phase to minimal changes in particle mobility. Since this effect is independent of MNP concentration, the sample handling is much simpler and robust. Our method thus may pave the way for deeper insights into complex and rapid binding dynamics of functionalization chemistry and can lead to a huge step forwards in point-of-care diagnostics as well as impacts other fields in research and industries.

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“…Last yet most importantly, the remanence measurements measure the magnetization at H = 0 , so there is minimal background signal, as such there is no need for complex pick up coils, as being used in magnetic nanoparticles spectroscopy. [ 35,36 ] This unique characteristic further advances the MNWs for high security authentication by discarding all adversary signals produced by third parties.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Nanowires toward Authentication

Kouhpanji

Stadler

2020

Part & Part Syst Charact

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Magnetic nanowires (MNWs) have been shown to be promising candidates for nanobarcoding and biolabeling over decades. However, surprisingly, they have never been realized successfully for these applications due to the lack of a reliable encoding strategy that allows reliable decoding of readout signatures. Here, a novel encoding/decoding approach is reported by tailoring the MNWs remanence spectrum that makes decoding the magnetic nanobarcodes feasible even though there is no prior knowledge regarding the readout remanence spectrum. The remanence spectra of several MNWs is tuned by varying their composition, dimensions, and arrangements to generate several distinct nanobarcodes. Furthermore, a simple automated decoding algorithm is illustrated to identify and verify the type and number of MNWs in unknown remanence spectra. The experimental and analytical approaches show that the remanence spectrum is a strong probe for reliable encoding/decoding because it employs three authentication factors that significantly enhance their security performance in nanobarcoding and biolabeling.

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Tracking the Growth of Superparamagnetic Nanoparticles with an In-Situ Magnetic Particle Spectrometer (INSPECT)

Cited by 15 publications

References 49 publications

Critical Offset Magnetic PArticle SpectroScopy for rapid and highly sensitive medical point-of-care diagnostics

Critical Offset Magnetic PArticle SpectroScopy for rapid and highly sensitive medical point-of-care diagnostics

COMPASS – rapid and highly sensitive medical point-of-care diagnostic

Magnetic Nanowires toward Authentication

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