Further reading:
T.-J. Wu, Y.-K. Tzeng, W.-W. Chang, C.-A.Cheng, Y. Kuo, C.-H. Chien,
H.-C. Chang, and J. Yu, "Tracking the engraftment and regenerative
capabilities of transplanted lung stem cells using fluorescent
nanodiamonds," Nature Nanotech. 8, 682-689 (2013).