title: Nanodiamonds as multi-purpose labels for microscopy.
abstract: Nanodiamonds containing fluorescent nitrogen-vacancy centers are increasingly attracting interest for use as a probe in biological microscopy. This interest stems from (i) strong resistance to photobleaching allowing prolonged fluorescence observation times; (ii) the possibility to excite fluorescence using a focused electron beam (cathodoluminescence; CL) for high-resolution localization; and (iii) the potential use for nanoscale sensing. For all these schemes, the development of versatile molecular labeling using relatively small diamonds is essential. Here, we show the direct targeting of a biological molecule with nanodiamonds as small as 70 nm using a streptavidin conjugation and standard antibody labelling approach. We also show internalization of 40 nm sized nanodiamonds. The fluorescence from the nanodiamonds survives osmium-fixation and plastic embedding making them suited for correlative light and electron microscopy. We show that CL can be observed from epon-embedded nanodiamonds, while surface-exposed nanoparticles also stand out in secondary electron (SE) signal due to the exceptionally high diamond SE yield. Finally, we demonstrate the magnetic read-out using fluorescence from diamonds prior to embedding. Thus, our results firmly establish nanodiamonds containing nitrogen-vacancy centers as unique, versatile probes for combining and correlating different types of microscopy, from fluorescence imaging and magnetometry to ultrastructural investigation using electron microscopy.
authors.affiliation: Groningen University, University Medical Center Groningen, Department of Biomedical Engineering, Antonius Deusinglaan 1, 9713, AW, Groningen, The Netherlands.
authors.forename: S R
authors.initials: SR
authors.lastname: Hemelaar
authors.affiliation: Groningen University, University Medical Center Groningen, Department of Cell Biology, Antonius Deusinglaan 1, 9713, AW, Groningen, The Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: de Boer
authors.affiliation: Groningen University, University Medical Center Groningen, Department of Biomedical Engineering, Antonius Deusinglaan 1, 9713, AW, Groningen, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Chipaux
authors.affiliation: Delft University of Technology, Dept. Imaging Physics, Lorentzweg 1, 2628, CJ, Delft, The Netherlands.
authors.forename: W
authors.initials: W
authors.lastname: Zuidema
authors.affiliation: Groningen University, University Medical Center Groningen, Department of Biomedical Engineering, Antonius Deusinglaan 1, 9713, AW, Groningen, The Netherlands.
authors.forename: T
authors.initials: T
authors.lastname: Hamoh
authors.affiliation: Groningen University, University Medical Center Groningen, Department of Biomedical Engineering, Antonius Deusinglaan 1, 9713, AW, Groningen, The Netherlands.
authors.forename: F Perona
authors.initials: FP
authors.lastname: Martinez
authors.affiliation: Groningen University, University Medical Center Groningen, Department of Biomedical Engineering, Antonius Deusinglaan 1, 9713, AW, Groningen, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Nagl
authors.affiliation: Delft University of Technology, Dept. Imaging Physics, Lorentzweg 1, 2628, CJ, Delft, The Netherlands.
authors.forename: J P
authors.identifier: http://orcid.org/0000-0003-4539-8772
authors.initials: JP
authors.lastname: Hoogenboom
authors.affiliation: Groningen University, University Medical Center Groningen, Department of Cell Biology, Antonius Deusinglaan 1, 9713, AW, Groningen, The Netherlands.
authors.forename: B N G
authors.initials: BNG
authors.lastname: Giepmans
authors.affiliation: Groningen University, University Medical Center Groningen, Department of Biomedical Engineering, Antonius Deusinglaan 1, 9713, AW, Groningen, The Netherlands. romana.schirhagl@gmail.com.
authors.forename: R
authors.initials: R
authors.lastname: Schirhagl