Hyperpolarized silicon particles have been shown to exhibit enormously long T1 relaxation at room temperature, making them favourable as novel imaging MR probes. To date, only large particles (average particle size (APS)=2.2 μm) could be efficiently polarized, restricting their in-vivo applicability.
The objective of the present work was to develop nanometre size hyperpolarized silicon-29 particles (APS= 55+/-12 nm) with superior MR properties. A maximum achievable polarization of 12.6% is reported with relaxation time of 42 min at room temperature. Applications of imaging of both solid and colloidal dispersion of silicon particles are demonstrated.