Sub-20-nm Fluorescent Nanodiamonds as Photostable Biolabels and Fluorescence Resonance Energy Transfer Donors

Fluorescent nanodiamonds (FNDs) of 10-20 nm in size have been produced by helium ion irradiation and isolated by differential centrifugation. Spectroscopic characterization of the FNDs with fluorescence microscopy and fluorescence correlation spectroscopy indicates perfect photostability and use as an alternative to far-red fluorescent proteins for biolabeling and fluorescence resonance energy transfer applications.