Sep 7, 2010
Nanodiamond-based biolabeling is forever
Organic dyes and fluorescent proteins are common fluorescent labels to identify cells and cellular organelles in fluorescence microscopy. But these fluoroprobes are restricted from long-term in vitro and in vivo observations because the organic compounds rapidly undergo photobleaching. Recently, nanoscale diamond has been employed as a luminescent optical marker, due to the intrinsic defect centres. The luminescence can be substantially enhanced when type Ib diamond nanocrystals are bombarded by a high-energy particle beam and then annealed to form negatively charged nitrogen-vacancy centres. The centre absorbs strongly in the green-orange region, and fluoresces efficiently in the far-red. The colour centre, which has already served as a single photon source and as a qbit in quantum communication, is exceptionally photostable. This fluorescent nanodiamond (FND) is an ideal candidate for long-term imaging and three-dimensional tracking in cellular environments at the single particle level.
Moreover, nanodiamond is highly biocompatible with low cytotoxicity and animal toxicity. The surface of the nanodiamond can be facilely derivatized with a wide range of functional groups. The surface-functionalized nanodiamond provides a versatile platform for conjugation with biomolecules such as peptides, proteins and DNA. Hence, nanodiamond is applicable as a drug and gene delivery vehicle. Most recently, sub-diffraction images of FNDs have been successfully acquired with far-field fluorescence microscopy and electron spin resonance. All the exciting new developments have added a new dimension for applications in biology and nanomedicine.
A review summarizing recent advances in the development of FNDs for optical bioimaging with single particle sensitivity and nanometric resolution can be found in the latest issue of J. Phys D: Applied Physics.
About the author
Professor Huan-Cheng Chang is a research fellow in the Institute of Atomic and Molecular Sciences at Academia Sinica, Taiwan. His current research interests are focused on nanodiamonds for biotechnological and biomedical applications. Dr Yuen Yung Hui is a postdoctoral fellow in Chang's group. He works in photophysics and the bioimaging of fluorescent nanodiamond. Professor Chia-Liang Cheng is a professor in the Department of Physics at National Dong-Hwa University. His research interests are diamond and carbon-related materials, and infrared and Raman spectroscopy of nanomaterials.