Hyperpolarized Nanodiamond Surfaces

Abstract

The widespread use of nanodiamond as a biomedical platform for drug-delivery, imaging, and subcellular tracking applications stems from its nontoxicity and unique quantum mechanical properties. Here, we extend this functionality to the domain of magnetic resonance, by demonstrating that the intrinsic electron spins on the nanodiamond surface can be used to hyperpolarize adsorbed liquid compounds at low fields and room temperature. By combining relaxation measurements with hyperpolarization, spins on the surface of the nanodiamond can be distinguished from those in the bulk liquid. These results are likely of use in signaling the controlled release of pharmaceutical payloads.

Nanodiamond-enhanced MRI via in situ hyperpolarization

“…39). Figure 1e also explains why previous DNP studies of ND solutions at 340 mT did not show Overhauser enhancement of freely diffusing water molecules in the bulk solution40. Instead, they showed solid effect DNP of 1 H nuclei adsorbed to the ND surface.…”

“…The 1 H enhancement we observe with the Overhauser effect is approximately two orders of magnitude larger, when accounting for ND concentration, than seen with solid effect hyperpolarization of water molecules adsorbed to ND surfaces40. Further, there is potential to increase the Overhauser enhancement towards the theoretical maximum of −330 (ref.…”

“…2b. Presumably, ρ is suppressed in the quasistatic nanophase by slow diffusion of water molecules and the increased paramagnetic nuclear relaxation rate40. 1 H nuclei ‘trapped' in the nanophase will experience rapid spin–lattice relaxation, giving the f we observe and an overall enhancement that depends on the specifics of each ND surface.…”

Minireview on Nuclear Spin Polarization in Optically-Pumped Diamond Nitrogen Vacancy Centers

“…19 They obtained the polarized signal of proton in water using strong microwave irradiation and they proved that the mechanism is from solid effect, not from Overhauser effect, which explains on the state of the water and its correlation time. Even though optical electron polarization was not used for this case and its polarization number is quite small, this result shows a great promise for NV center as a polarization transfer source.…”

“…Especially, many studies described that P1 center (diamond defect, carbon is substituted by nitrogen) and surface unpaired electrons are the useful sources for polarization transfer. 13,[15][16][17][18][19] This review will be focused only on one defect, Nitrogen Vacancy Center (NV center), since we can theoretically achieve ~100 % hyperpolarized electron spin in room temperature. Its detailed physics were introduced in a review by Doherty M. et al 20 Some of its basic physics will be discussed here.…”