Monodisperse Five-Nanometer-Sized Detonation Nanodiamonds Enriched in Nitrogen-Vacancy Centers

Daiki Terada, Takuya F. Segawa, Alexander I. Shames, Shinobu Onoda, Takeshi Ohshima, Eiji Osawa, Ryuji Igarashi, Masahiro Shirakawa

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Nanodiamonds containing negatively charged nitrogen-vacancy (NV-) centers are versatile nanosensors thanks to their optical and spin properties. While currently most fluorescent nanodiamonds in use have at least a size of a few tens of nanometers, the challenge lies in engineering the smallest nanodiamonds containing a single NV- defect. Such a tiny nanocrystal with a single NV- center is an optical spin label for biomolecules, which can be detected in a fluorescence microscope. In this paper, we address two key issues toward this goal using detonation nanodiamonds (DNDs) of 4-5 nm in size. The DND samples are treated first with electron irradiation to create more vacancies. With the aid of electron paramagnetic resonance (EPR) spectroscopy, we confirm a steady increase of negatively charged NV- centers with higher fluence. This leads to a 4 times higher concentration in NV- defects after irradiation with 2 MeV electrons at a fluence of 5-1018 e-/cm2. Interestingly, we observe that the annealing of DND does not increase the number of NV- centers, which is in contrast to bulk diamond and larger nanodiamonds. Since DNDs are strongly aggregated after the irradiation process, we apply a boiling acid treatment as a second step to fabricate monodisperse DNDs enriched in NV- centers. These are two important steps toward optical spin labels having a single-digit nanometer range size that could be used for bioimaging and nanosensing.

Original languageEnglish
Pages (from-to)6461-6468
Number of pages8
JournalACS Nano
Issue number6
StatePublished - 25 Jun 2019


  • annealing
  • detonation nanodiamonds (DNDs)
  • electron irradiation
  • electron paramagnetic resonance (EPR)
  • nanodiamonds
  • nitrogen-vacancy center (NV center)
  • optically detected magnetic resonance (ODMR)

ASJC Scopus subject areas

  • Materials Science (all)
  • Engineering (all)
  • Physics and Astronomy (all)


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