Nanodiamond in cancer theranostics

Nanodiamonds (NDs) are emerging as a promising platform for theranostic particles since they offer a single platform that possesses multiple important properties. These include a simple mechanism of synthesis, small size, chemical inertness, a variety of available surface functional groups, good biocompatibility, stable fluorescence, and a long fluorescence lifetime. The use of NDs to deliver anticancer drugs has been an important ND application since NDs can increase chemosensitivity, sustain drug release, and minimize drug side effects. These unique properties have stimulated the application of NDs to cancer imaging and therapy. In this review, we offer a brief introduction of ND structure and their functional properties. This is followed by a summary of recent uses of NDs for imaging purposes, including fluorescent imaging, magnetic resonance imaging (MRI), and other imaging technologies. Special concern is given to studies focusing on NDs use for anticancer drug delivery, anticancer gene delivery, photothermal and photodynamic therapies, and multifunctional combination therapy. We then discuss ND biocompatibility and toxicity in various cells and animal models. Finally, we also discuss the main problems to be solved by future research before NDs can be put to clinical use. The purpose of this review is to provide a side-by-side comparison of studies reporting ND-mediated cancer imaging therapy so that readers can assess the potential clinical applications of ND and have the background necessary to understand the clinical test results associated with ND-related therapy in animals and humans.