Tailored nanodiamonds for hyperpolarized C13 MRI

Abstract

Nanodiamond is poised to become an attractive material for hyperpolarized 13 C MRI if large nuclear polarizations can be achieved without the accompanying rapid spin-relaxation driven by paramagnetic species. Here we report enhanced and long-lived 13 C polarization in synthetic nanodiamonds tailored by acid-cleaning and air-oxidation protocols. Our results separate the contributions of different paramagnetic species on the polarization behavior, identifying the importance of substitutional nitrogen defect centers in the nanodiamond core. These results are likely of use in the development of nanodiamond-based imaging agents with size distributions of relevance for examining biological processes. arXiv:1909.04842v1 [cond-mat.mes-hall]

Efficient Conversion of Nitrogen to Nitrogen-Vacancy Centers in Diamond Particles with High-Temperature Electron Irradiation

“…The 100 nm and 25 nm samples show respectively 27 ± 5 ppm and 5.2 ± 1.0 ppm of P1. Fainting P1 signal with decreasing particle size is consistent with data already reported in the literature for HPHT nanodiamonds obtained upon milling [28,29]. One can hypothesize that electron acceptors or donors on the particle surface are responsible for conversion of a fraction of P1 in NDs to nitrogen with a different charge state, or, as it has been proposed, that part of P1 centers show a different (narrowed) spectrum in NDs due to strong exchange interaction with surface dangling bonds [30].…”

P1 Center Electron Spin Clusters Are Prevalent in Type Ib Diamonds

“…One of the most widely studied defects is the nitrogen vacancy (NV) center, which consists of a substitutional nitrogen atom and an adjacent vacancy in the diamond lattice. − The NV center has been found to exhibit remarkable properties, including long spin coherence times, room temperature operation, and optical addressability. − As a result, it has been used in a range of applications, such as single-photon sources, nanoscale magnetic sensors, and quantum memories. − NV centers arise from P1 centers that are single substitutional nitrogen defects in the diamond lattice that also have a long coherence time, even at room temperature. , Studying the spatial distribution of the P1 and NV centers is critical for many reasons. For example, P1 centers are a major source of polarization for nearby carbon nuclei that can be used for quantum sensing applications. − P1 centers are also the main culprit for the relaxation of the NV center electron paramagnetic resonance (EPR) signal and coherence and hence may be the bottleneck in applications where long coherence times from the NV center are needed for sensing applications. ,− Knowledge of the microscopic spin distribution is essential for the investigation of exotic physics in disordered dipolar spin systems. , Diamond is also a promising polarization agent for dynamic nuclear polarization (DNP) for achieving high polarization of intrinsic 13 C nuclear spins for sensing or imaging applications ,− or of nuclear spins of external analytes …”

Nanomaterials for hyperpolarized nuclear magnetic resonance and magnetic resonance imaging

“…Their long 13 C T 1 (from 1 min for synthetic NDs of 18 nm diameter up to 160 min for natural NDs of 2 μm diameter) (Boele et al, 2020) and large variety of possible surface modifications (Qin et al, 2021), make NDs interesting as an in vivo MRI contrast agent. The first study using NDs in an MRI setting was conducted in 2018, where an in vitro MRI was acquired.…”