Paramagnetic Sensing by Nanodiamond via Magnetically-Induced Fluorescence Contrast

Paramagnetic species such as free radicals and transition metal ions play a major role across many aspects of biology. Misregulation of paramagnetic free radicals, for example, has been implicated in a number of diseases (<i>e.g</i>., cardiovascular disease, Alzheimer's disease, cancer, among others). The ability to spatially resolve cellular redox mediators could help draw relationships in disease pathogenesis through a detailed understanding of the location and concentrations of intracellular redox mediators. As the fluorescence of Nitrogen-Vacancy (NV) centers in nanodiamond is sensitive to the NV’s magnetic environment, spin state can be read optically. By measuring fluorescence changes induced by the particle’s environments with respect to laboratory generated static fields, the generated contrast can report on the local paramagnetic environment. Though sensitive paramagnetic responsivity has already been shown via T1 relaxation measurements, by reading this contrast instead we attempt to simply the method for straightforward implementation using conventional microscopy. In the context radical sensing, developments are presented on improving and implementing the ability of NV color centers in nanodiamond to optically sense paramagnetic analytes through magnetically-induced fluorescence contrast.