Molecular imaging by optically-detected electron spin resonance of nitrogen-vacancies in nanodiamond

TL;DR

This paper introduces nanodiamond imaging, a novel molecular imaging technique using nitrogen-vacancy centers in nanodiamonds for high-sensitivity, high-resolution, noninvasive biomedical imaging without ionizing radiation.

Contribution

The paper demonstrates a new optical-magnetic resonance imaging method utilizing nanodiamonds with NV centers for targeted, in-vivo molecular imaging with potential advantages over existing modalities.

Findings

Achieved high sensitivity and spatial resolution in nanodiamond imaging.

Demonstrated imaging of nanodiamond targets in chicken breast tissue.

Proposed applications include small-animal imaging and tumor margin detection.

Abstract

Molecular imaging refers to a class of noninvasive biomedical imaging techniques with the sensitivity and specificity to image biochemical variations in-vivo. An ideal molecular imaging technique visualizes a biochemical target according to a range of criteria, including high spatial and temporal resolution, high contrast relative to non-targeted tissues, depth-independent penetration into tissue, lack of harm to the organism under study, and low cost. Because no existing molecular imaging modality is ideal for all purposes, new imaging approaches are needed. Here we demonstrate a novel molecular imaging approach, called nanodiamond imaging, that uses nanodiamonds containing nitrogen-vacancy (NV) color centers as an imaging agent, and image nanodiamond targets in pieces of chicken breast. Nanodiamonds can be tagged with biologically active molecules so they bind to specific receptors; their distribution can then be quantified in-vivo via optically-detected magnetic resonance of the NVs. In effect, we are demonstrating Optically-Detected Functional-Electron-Spin-Resonance-Imaging, OD-f-ESRI. By combining optical detection with magnetic resonance, nanodiamond imaging achieves high sensitivity and high spatial resolution. It is absent of the complications of ionizing radiation, and the cost should be similar to all-optical imaging. Because nanodiamond imaging is limited by the depth of optical penetration into tissue to depths of a few cm, nanodiamond imaging should open up new avenues of investigation for applications where high depth penetration is not required, such as in small-animal imaging, tumor margin imaging, sentinel lymph node mapping, and perhaps mammography.