Time-Resolved Diamond Magnetic Microscopy of Superparamagnetic Iron-Oxide Nanoparticles
Superparamagnetic iron-oxide nanoparticles (SPIONs) are promising probes for biomedical imaging, but the heterogeneity of their magnetic properties is difficult to characterize with existing methods. Here, we perform widefield imaging of the stray magnetic fields produced by hundreds of isolated ~30-nm SPIONs using a magnetic microscope based on nitrogen-vacancy centers in diamond. By analyzing the SPION magnetic field patterns as a function of applied magnetic field, we observe substantial field-dependent transverse magnetization components that are typically obscured with ensemble characterization methods. We find negligible hysteresis in each of the three magnetization components for nearly all SPIONs in our sample. Most SPIONs exhibit a sharp Langevin saturation curve, enumerated by a characteristic polarizing applied field, B_c. The B_c distribution is highly asymmetric, with a standard deviation (1.4 mT) that is larger than the median (0.6 mT). Using time-resolved magnetic microscopy, we directly record SPION N\'eel relaxation, after switching off a 31 mT applied field, with a temporal resolution of ~60 ms that is limited by the ring-down time of the electromagnet coils. For small bias fields B_{hold}=1.5-3.5 mT, we observe a broad range of SPION N\'eel relaxation times--from milliseconds to seconds--that are consistent with an exponential dependence on B_{hold}. Our time-resolved diamond magnetic microscopy study reveals rich SPION sample heterogeneity and may be extended to other fundamental studies of nanomagnetism.
Authors
- Dale L. Huber (ORCID: https://orcid.org/0000-0001-6872-8469)
- Víctor M. Acosta (ORCID: https://orcid.org/0000-0003-0058-9954)
- Todor Karaulanov (ORCID: https://orcid.org/0000-0001-9833-9915)
- Abdelghani Laraoui (ORCID: https://orcid.org/0000-0002-2811-8030)
- Nazanin Mosavian
- Andris Bērziņš (ORCID: https://orcid.org/0000-0002-5265-3922)
- Forrest Hubert
- Maxwell D. Aiello (ORCID: https://orcid.org/0000-0002-1253-0805)
- Maziar Saleh Ziabari (ORCID: https://orcid.org/0000-0002-1889-0940)
- Jeffrey E. Shield (ORCID: https://orcid.org/0000-0002-1415-2115)
- Nathaniel Ristoff (ORCID: https://orcid.org/0000-0001-6829-0049)
- Pauli Kehayias (ORCID: https://orcid.org/0000-0002-7597-4358)
- Jānis Šmits (ORCID: https://orcid.org/0000-0002-5835-9345)
- Andrey Jarmola (ORCID: https://orcid.org/0000-0001-5439-1324)
- Joshua T. Damron (ORCID: https://orcid.org/0000-0003-3409-0190)
- Ilja Fescenko (ORCID: https://orcid.org/0000-0002-1273-703X)
- Andrew Mounce (ORCID: https://orcid.org/0000-0002-8115-2764)
- Yaser Silani (ORCID: https://orcid.org/0000-0002-3621-1243)
- A. Pérez (ORCID: https://orcid.org/0009-0006-4148-5560)
- Bryan A. Richards
- Michael Lilly (ORCID: https://orcid.org/0009-0002-5212-6230)
- Daniel Egbebunmi (ORCID: https://orcid.org/0009-0003-1854-0814)
Institutions
- Oak Ridge National Laboratory (US)
- University of California System (US)
- NeuroSigma (United States) (US)
- Sandia National Laboratories (US)
- MMR Technologies (United States) (US)
- Center for Integrated Nanotechnologies (US)
- University of Latvia (LV)
Publication Details
- Journal
- ACS Nano
- Published
- 2025-03-07
- DOI
- https://doi.org/10.1021/acsnano.4c16703
- Citations
- 4
- Primary Topic
- Characterization and Applications of Magnetic Nanoparticles
- Type
- article
- Field-Weighted Citation Impact
- 2.70
Funders
- Gordon and Betty Moore Foundation
- National Institute of Mental Health
- National Institute of General Medical Sciences
- National Institute of Biomedical Imaging and Bioengineering
- Division of Materials Research
- Division of Chemistry
- Division of Emerging Frontiers in Research and Innovation