Direct hyperpolarization of micro- and nanodiamonds for bioimaging applications – Considerations on particle size, functionalization and polarization loss

[Display omitted] •Commercially available micro/nanoparticles of diamonds can be polarized up to 22%.•The surface modification with polyethylene glycol did not change DNP properties.•Images of a phantom could be recorded up to 30 min after dissolution. Due to the inherently long relaxation time of 13C spins in diamond, the nuclear polarization enhancement obtained with dynamic nuclear polarization can be preserved for a time on the order of about one hour, opening up an opportunity to use diamonds as a new class of long-lived contrast agents. The present communication explores the feasibility of using 13C spins in directly hyperpolarized diamonds for MR imaging including considerations for potential in vivo applications.