Fluorescent Nanodiamonds In Vitro Imaging In Vivo Imaging Photostability of Fluorescent Diamond vs Rhodamine Dye As rhodamine fluorescence quenches, FND fluorescence remains stable, with variation only from drying of the liquid sample. Fluorescent Nano-Diamonds In Vitro Imaging Directional Conjugation Enzymatic Attachment Non-Enzymatic Attachment In Vivo Imaging