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

Abstract

Nanodiamonds containing negatively-charged nitrogen-vacancy (NV -) centers are versatile nanosensors thanks to their unique 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 size nanodiamonds containing a single NVdefect. Such a tiny nanocrystal with a single NVcenter is an "optical spin label" for biomolecules, which can be detected in a fluorescence microscope. In this paper, we address two key issues towards this goal using detonation nanodiamonds (DND) 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 NVcenters with higher fluence. This leads to a four times higher concentration in NVdefects after irradiation with 2MeV-electrons at a fluence of 5×10 18 e -/cm 2 . Interestingly, we observe that annealing of DND does not increase the number of NVcenters, which is in contrast to bulk diamond and larger nanodiamonds. Since DND are strongly aggregated after the irradiation process, we apply a boiling acid treatment as a second step to fabricate mono-disperse DND enriched in NVcenters. These are two important steps towards "optical spin labels" having single digit nanometer range size that could be used for bioimaging and nanosensing.

Development of gold catalysts supported by unreducible materials: Design and promotions

“…Furthermore, nanodiamonds (ND) are also a kind of special carbon materials with a particle diameter of approximately 4-5 nm [56,57]. In particular, the presence of crystalline carbon with hybrid orbitals allows the ND to exhibit unexpected surface activities.…”

Fluorescence and Physico-Chemical Properties of Hydrogenated Detonation Nanodiamonds

“…DNDs with various surface chemistries and different sizes show fluorescence [13,[17][18][19], most of which appears to originate from non-diamond carbon rather than the diamond particle core [13], the latter being preferred for use in bioimaging applications for its better photostability [20]. However, it is known that DNDs can host fluorescent diamond lattice defects such as the nitrogen-vacancy (NV) center [21][22][23]. Our previous work has shown that among DNDs with several different surface modifications, hydrogenated DNDs overall exhibited spectral fluorescence properties that most closely resemble NV fluorescence [13], prompting further research to investigate the origin of this fluorescence.…”

Room temperature hyperpolarization of polycrystalline samples with optically polarized triplet electrons: Pentacene or Nitrogen-Vacancy center in diamond?

“…were "made white" by oxidation in air at 550 • C for 2 h, followed by boiling acid cleaning in H 2 SO 4 /HNO 3 (3:1, 125 • C) for 3 d (Terada et al, 2019). Both diamond samples contain 1.1 % natural abundance 13 C. (iii) 4 mg of PBA powder, with 0.04 mol% (2.6 × 10 18 cm −3 ) concentration of pentacene.…”