Title: Phase-Encoded Hyperpolarized Nanodiamond for Magnetic Resonance Imaging,
Abstract: Surface-functionalized nanomaterials can act as theranostic agents that
detect disease and track biological processes using hyperpolarized magnetic
resonance imaging (MRI). Candidate materials are sparse however, requiring
spinful nuclei with long spin-lattice relaxation (T1) and spin-dephasing times
(T2), together with a reservoir of electrons to impart hyperpolarization. Here,
we demonstrate the versatility of the nanodiamond material system for
hyperpolarized 13C MRI, making use of its intrinsic paramagnetic defect
centers, hours-long nuclear T1 times, and T2 times suitable for spatially
resolving millimeter-scale structures. Combining these properties, we enable a
new imaging modality that exploits the phase-contrast between spins encoded
with a hyperpolarization that is aligned, or anti-aligned with the external
magnetic field. The use of phase-encoded hyperpolarization allows nanodiamonds
to be tagged and distinguished in an MRI based on their spin-orientation alone,
and could permit the action of specific bio-functionalized complexes to be
directly compared and imaged.