Beyond the sparkle: the impact of nanodiamonds as biolabeling and therapeutic agents.

A paper by Treussart and co-workers in this issue demonstrates the application of photoluminescent nanodiamonds for intracellular labeling as well as mechanistic cellular uptake studies. Findings from this paper reveal that optimal photoluminescence of nitrogen-vacancy color centers can be attained with photostability and no photoblinking, enabling continuous tracking in the cytoplasm over sustained time scales. In addition to the fluorescent properties of the nanodiamonds, internalization assays reveal a primarily endocytic uptake process. A high degree of nanodiamond ( approximately 46 nm in diameter) and endosome colocalization as well as cytoplasmic presence of smaller nanodiamonds was observed. Several attributes of the nanodiamond particles are elucidated in this and other recent studies, ranging from their stability as imaging agents to their potential as intracellular molecular delivery vehicles. These findings give insight into the use of nanodiamonds as an emerging platform for therapeutic and diagnostic ("theranostic") nanomedicine, forging new foundations and criteria for continued nanodiamond engineering toward downstream clinical relevance and impact.