Nanodiamond molecular imaging with enhanced contrast and expanded field of view

Abstract

Abstract. 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 mm 3 voxel) of 1.6 mM mm 3 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.

Understanding the Magnetic Resonance Spectrum of Nitrogen Vacancy Centers in an Ensemble of Randomly Oriented Nanodiamonds

“…We also point out that in fluorescence imaging of nanodiamonds, magnetic resonance control of NVspins enhances contrast and can provide an additional degree of spatial information through the application of magnetic field gradients 38 . Determining the imaging point spread function in this case is equivalent to calculating the ODMR spectrum 39 . Understanding the ensemble ODMR spectrum is critical to extending ODMR imaging to stronger gradients and higher fields where narrow overtone transitions will provide enhanced resolution.…”

3D tomographic magnetofluorescence imaging of nanodiamonds

“…Specifically, ODESR in zero field appears as a fluorescence change by (B = 0) = 0.1% when microwave radiation at appropriate frequency is applied. (|B|) decreases by a factor 2 or more for a field strength |B| ≥ δB = 5 G [3]. This is the effect used in gradient imaging.…”

“…Non-traditional imaging, i.e. without the use of lenses, is also possible with FNDs (or other systems with a magnetic-field dependent fluorescence) [1][2][3]. Basically, the approach uses an inhomogeneous magnetic field with a field-free line, i.e.…”

“…Hegyi and Yablonovitch [2,3] demonstrated gradient imaging based on ODESR. Their imaging system combined a permanent magnet QP field, a solenoidal dipole (i.e.…”

“…In this paper we pursue the development of a technique [1][2][3] that may in the future lead to biochemical 3D imaging in the animal or human body, in vivo. The method is based on the combination of fluorescent markers distributed within the body, having magnetic-field-dependent fluorescence efficiency, and an inhomogeneous magnetic field pervading the body.…”