Surface engineering and applications of nanodiamonds in cancer treatment and imaging

Nanodiamonds (NDs) are emerging as a promising platform for theranostic particles because they unite a spectrum of important properties into a single agent, including facile synthesis, small size, inertness, rich surface functional groups, biocompatibility, stable fluorescence and long fluorescence lifetime. These unique properties have stimulated the application of NDs in cancer treament and imaging. The majority of these applications rely on the rational engineering of the particle surface, as the surface plays a critical role in carrying bioactive molecules, resisting aggregation and constructing composite materials. In this review, recent developments of functionalising NDs for cancer treatment and imaging purposes are discussed. A brief introduction in the structure of NDs and properties of NDs will be given, followed by a summary of various surface functionalisation methods. The latter part is organised in three subsections: NDs coated with bioactive compounds, NDs coated with synthetic polymers and NDs/inorganic composites.