Fluorescent Nanodiamonds for Molecular and Cellular Bioimaging

Abstract

Fluorescent nanodiamonds (FNDs) have generated immense interest as fluorescent probes for biomedical imaging due to their unparalleled photostability and potential biocompatibility. Diamond can become fluorescent due to defects; in particular, nitrogen-vacancy (NV) centers in diamond are fluorescent sources with remarkable optical properties. FNDs containing NV centers do not photo-bleach or blink, their fluorescence emission can be modulated with a magnetic field making them one of the most sensitive magnetic field sensors, and they have fluorescence lifetime longer than fluorescent biomolecules. Commercial cost-effective availability along with method development for easy functionalization and imaging have promoted vigorous research on using FNDs as versatile bioimaging probes. Methods to coat FNDs with silica for easy functionalization for biomedical applications and to image FNDs background-free in vitro and in vivo by applying an alternating magnetic field with a conventional fluorescence microscope have been achieved. Functionalized FNDs have been used to track biomolecules in vitro and in vivo. For future use in humans and regulatory approval, it is necessary to study biodistribution, biotoxicity, and clearance, all of which have been studied in animals. This review gives an overview of the entire spectrum of FND related research.