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Issue 24, 2018
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Ultrasensitive detection enabled by nonlinear magnetization of nanomagnetic labels

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Abstract

Geometrically confined magnetic particles due to their unique response to external magnetic fields find a variety of applications, including magnetic guidance, heat and drug delivery, magneto-mechanical actuation, and contrast enhancement. Highly sensitive detection and imaging techniques based on the nonlinear properties of nanomagnets were recently proposed as innovative strong-translational potential methods applicable in complex, often opaque, biological systems. Here we report on the significant enhancement of the detection capability using optical-lithography-defined, ferromagnetic iron–nickel alloy disk-shaped particles. We show that an irreversible transition between strongly non-collinear (vortex) and single domain states, driven by an alternating magnetic field, translates into a nonlinear magnetic response that enables ultrasensitive detection of these particles. The record sensitivity of ∼3.5 × 10−9 emu, which is equivalent to ∼39 pg of magnetic material is demonstrated at room temperature for arrays of patterned disks. We also show that unbound disks suspended in the aqueous buffer can be successfully detected and quantified in real-time when administered into a live animal allowing for tracing of their biodistribution. The use of nanoscale ferromagnetic particles with engineered nonlinear properties opens prospects for further enhancing the sensitivity, scalability, and tunability of noise-free magnetic tag detection in high-background environments for various applications spanning from biosensing and medical imaging to anti-counterfeiting technologies.

Graphical abstract: Ultrasensitive detection enabled by nonlinear magnetization of nanomagnetic labels

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Publication details

The article was received on 22 Feb 2018, accepted on 12 May 2018 and first published on 05 Jun 2018


Article type: Paper
DOI: 10.1039/C8NR01511B
Citation: Nanoscale, 2018,10, 11642-11650
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    Ultrasensitive detection enabled by nonlinear magnetization of nanomagnetic labels

    M. P. Nikitin, A. V. Orlov, I. L. Sokolov, A. A. Minakov, P. I. Nikitin, J. Ding, S. D. Bader, E. A. Rozhkova and V. Novosad, Nanoscale, 2018, 10, 11642
    DOI: 10.1039/C8NR01511B

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