title: Coherent anti-Stokes Raman scattering microscopy of single nanodiamonds.
abstract: Nanoparticles have attracted enormous attention for biomedical applications as optical labels, drug-delivery vehicles and contrast agents in vivo. In the quest for superior photostability and biocompatibility, nanodiamonds are considered one of the best choices due to their unique structural, chemical, mechanical and optical properties. So far, mainly fluorescent nanodiamonds have been utilized for cell imaging. However, their use is limited by the efficiency and costs in reliably producing fluorescent defect centres with stable optical properties. Here, we show that single non-fluorescing nanodiamonds exhibit strong coherent anti-Stokes Raman scattering (CARS) at the sp(3) vibrational resonance of diamond. Using correlative light and electron microscopy, the relationship between CARS signal strength and nanodiamond size is quantified. The calibrated CARS signal in turn enables the analysis of the number and size of nanodiamonds internalized in living cells in situ, which opens the exciting prospect of following complex cellular trafficking pathways quantitatively.
authors.affiliation: Cardiff University School of Biosciences, Museum Avenue, Cardiff CF10 3AX, UK.
authors.forename: Iestyn
authors.initials: I
authors.lastname: Pope
authors.affiliation: Cardiff University School of Biosciences, Museum Avenue, Cardiff CF10 3AX, UK.
authors.forename: Lukas
authors.initials: L
authors.lastname: Payne
authors.affiliation: Cardiff University School of Biosciences, Museum Avenue, Cardiff CF10 3AX, UK.
authors.forename: George
authors.initials: G
authors.lastname: Zoriniants
authors.affiliation: Cardiff University School of Physics and Astronomy, The Parade, Cardiff CF24 3AA, UK.
authors.forename: Evan
authors.initials: E
authors.lastname: Thomas
authors.affiliation: Cardiff University School of Physics and Astronomy, The Parade, Cardiff CF24 3AA, UK.
authors.forename: Oliver
authors.initials: O
authors.lastname: Williams
authors.affiliation: Cardiff University School of Biosciences, Museum Avenue, Cardiff CF10 3AX, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Watson
authors.affiliation: Cardiff University School of Physics and Astronomy, The Parade, Cardiff CF24 3AA, UK.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Langbein
authors.affiliation: Cardiff University School of Biosciences, Museum Avenue, Cardiff CF10 3AX, UK.
authors.forename: Paola
authors.initials: P
authors.lastname: Borri
mesh_terms: D006367:HeLa Cells; D006801:Humans; D008853:Microscopy / Q000379:methods*; D058612:Nanodiamonds / Q000032:analysis* / Q000648:ultrastructure*; D061848:Optical Imaging / Q000379:methods; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D058612:Nanodiamonds