Detecting nucleic acid fragments in serum using a magnetically modulated sandwich assay

Michael Margulis, Saar Ashri, Meir Cohen, Amos Danielli

Research output: Contribution to journalLetterpeer-review

10 Scopus citations


We present a novel assay for rapid and highly sensitive detection of specific nucleic acid fragments in human serum. In a magnetic modulation biosensing (MMB) system, magnetic beads and fluorescently labeled probes are attached to the target analyte and form a “sandwich” complex. An alternating external magnetic field gradient condenses the magnetic beads (and hence the target molecules with the fluorescently labeled probes) to the detection volume and sets them in a periodic motion, in and out of a laser beam. A synchronous detection enables the removal of background signal from the oscillating target signal without complicated sample preparation. The high sensitivity of the MMB system, combined with the specificity of a sandwich hybridization assay, enables detection of DNA fragments without enzymatic signal amplification. Here, we demonstrate the sensitivity of the assay by directly detecting the EML4-ALK oncogenic translocation sequence spiked in human serum. The calculated limit of detection is 1.4 pM, which is approximately 150 times better than a conventional plate reader. In general, the MMB-assisted SHA can be implemented in many other applications for which enzymatic amplification, such as PCR, is not applicable and where rapid detection of specific nucleic acid targets is required.

Original languageEnglish
Article numbere201900104
JournalJournal of Biophotonics
Issue number11
StatePublished - 1 Nov 2019

Bibliographical note

Publisher Copyright:
© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim


  • biosensors
  • fluorescence
  • magnetically modulated
  • sandwich hybridization assay
  • translocation


Dive into the research topics of 'Detecting nucleic acid fragments in serum using a magnetically modulated sandwich assay'. Together they form a unique fingerprint.

Cite this