Further reading:
C.-C. Fu, H.-Y. Lee, K. Chen, T.-S. Lim, H.-Y. Wu, P.-K. Lin, P.-K. Wei, P.-H. Tsao, H.-C. Chang, and W. Fann, "Characterization and application of single fluorescent nanodiamonds as cellular biomarkers,"Proc. Natl. Acad. Sci. USA 104, 727-732 (2007).