Direct magnetic characterization of individual nanoparticles for optimized diagnostic imaging - Project Summary
ODMR Technologies, Inc. and Prof. Victor Acosta's group at University of New Mexico (UNM) are developing a
diamond-chip platform capable of ¿direct magnetic characterization of individual nanoparticles for optimized
diagnostic imaging. ¿Our team is a spinoff from academic collaborations in the emerging field of diamond
photonic sensors; a field we helped create nearly a decade ago. After years of refining this technology in the
lab, we are ready to commercialize our most promising devices.
Magnetic nanoparticle (MNP) research has seen a flurry of activity in recent years, owing to potential
applications in catalysis, data storage, biosensing, medical imaging, including magnetic resonance imaging
(MRI), magnetic particle imaging, and magnetic relaxation imaging (MRX), drug delivery, and hyperthermia
treatment. These applications would benefit from using MNPs with highly uniform composition, size, shape,
and magnetic properties. However, MNP production is notoriously plagued by reproducibility problems,
inaccurate specifications, and a lack of common practices. Tools for quantitative magnetic measurements of
individual nanoparticles are not commercially available. Advanced characterization tools are often either
inaccessible (due to cost and maintenance) or simply do not exist. If the cost, accuracy, versatility, and
throughput of proposed instruments can be improved they could have a dramatic impact on MNP applications.
Developing a diamond-chip platform for high-sensitivity, parallel characterization of individual MNPs is the
focus of this proposal. The magnetic hysteresis and relaxation properties of thousands of individual MNPs will
be simultaneously characterized using a magnetic microscope based on nitrogen-vacancy (NV) color centers
doped near the surface of a diamond chip. The magnetic measurements for each individual MNP will be
correlated with its composition and morphology, as determined by high-resolution transmission electron
microscopy. Unlike existing techniques, the proposed platform works at ambient conditions and offers high
throughput (>1000 individual particles per 10 min).
To date, we have built a setup designed for imaging particles with ~100 nm core diameters. In the proposed
research plan, we will optimize the benchtop prototype for ~20 nm sized particles. Our goal is to build a
benchtop magnetic imaging apparatus with 1 µT sensitivity in (400 nm)¿2 resolved pixels, 0-200 mT tuning
range, and >1000 frames per second. Next, we will characterize the magnetic dynamics of superparamagnetic
iron oxide nanoparticles (SPIONs) with 15-22 nm diameter, with a goal of improving their applicability in
biomedicine. We will obtain hysteresis curves and magnetization decay curves with record throughput.
Correlative TEM and magnetic images of numerous individual SPIONs will be obtained, and may finally
unambiguously elucidate the relationship between SPION size, shape, magnetization relaxation, and
hysteresis curve properties.
