Bioimaging and quantum sensing with ion-irradiated nanodiamonds
Huan-Cheng Chang (Academia Sinica, Taiwan)
Seminar co-hosted by François Treussart
SPECIAL TIME AND LOCATION
As a wide band-gap material, diamond can contain a variety of atomic defects or impurities as color centers. Some of the color centers are highly luminescent, while others are luminescent with a very low quantum yield. For nanoscale diamonds (NDs) containing a high-density ensemble of vacancy-related defect centers, they are useful as nanoprobes for bioimaging and quantum sensing both in vitro and in vivo. In this seminar, we will show how ion-irradiated NDs can be routinely produced in our laboratory. Three examples of the applications by utilizing nitrogen-vacancy (NV−) centers and neutral vacancy (V0 or GR1) centers in NDs are discussed. First, we will present our results of using fluorescence lifetime imaging microscopy to achieve background-free real-time imaging of fluorescent NDs (denoted as FNDs) in living organisms such as C. elegans. With 100-nm FNDs conjugated with yolk lipoprotein complexes, we demonstrate that the nanoparticles serve well as a biomolecular nanocarrier without significantly altering the functionality of the cargos for intercellular transport, cell-specific targeting, and long-term imaging applications in vivo. Second, we report our recent work on the development of highly ion-irradiated NDs (denoted as INDs) as a photoacoustic contrast agent for deep-tissue imaging. The particles are so extensively damaged that graphitization occurs concurrently with the generation of the GR1 centers. Although the IND of ~40 nm in diameter has a much smaller absorption coefficient than gold nanorods (GNRs) of similar dimensions at 1064 nm, it shows a better performance due to higher thermal stability and a lower nanobubble formation threshold of the carbon-based nanomaterial. Finally, we apply the NV− centers in 100-nm FNDs for nanoscale temperature sensing by optically detected magnetic resonance. We conjugate FNDs with GNRs and employ them as both a nanoheater and a nanothermometer in solution and cells. The integration of heating and temperature sensing functions on the same particles opens an opportunity for active and high-precision control of temperature at the nanoscale by pure optical means.