Nanodiamond molecular imaging with enhanced contrast and expanded field of view.

Nanodiamond imaging is a new molecular imaging modality that takes advantage of nitrogen-vacancy (NV) centers in nanodiamonds to image a distribution of nanodiamonds with high sensitivity and high spatial resolution. Since nanodiamonds are nontoxic and are easily conjugated to biomolecules, nanodiamond imaging can potentially elicit physiological information from within a living organism. The position of the nanodiamonds is measured using optically detected electron spin resonance of the NVs. In a previous paper, we described a proof-of-principle nanodiamond imaging system with the ability to image in two dimensions over a 1×1  cm field of view and demonstrated imaging within scattering tissue. Here, we describe a second-generation nanodiamond imaging system with a field of view of 30×200  mm, and with three-dimensional imaging potential. The new system has a comparable spatial resolution of 1.2 mm FWHM and a sensitivity (in terms of the concentration of carbon atoms in a  mm3  voxel) of 1.6  mM mm3 Hz-1/2, a 3-dB improvement relative to the old system. We show that imaging at 2.872 GHz versus imaging at 2.869 GHz offers a 1.73× improvement in sensitivity with only a 20% decrease in resolution and motivate this by describing the observed lineshape starting from the NV spin Hamiltonian.