Mass production and dynamic imaging of fluorescent nanodiamonds

Abstract

Fluorescent nanodiamond is a new nanomaterial that possesses several useful properties, including good biocompatibility, excellent photostability and facile surface functionalizability. Moreover, when excited by a laser, defect centres within the nanodiamond emit photons that are capable of penetrating tissue, making them well suited for biological imaging applications. Here, we show that bright fluorescent nanodiamonds can be produced in large quantities by irradiating synthetic diamond nanocrystallites with helium ions. The fluorescence is sufficiently bright and stable to allow three-dimensional tracking of a single particle within the cell by means of either one- or two-photon-excited fluorescence microscopy. The excellent photophysical characteristics are maintained for particles as small as 25 nm, suggesting that fluorescent nanodiamond is an ideal probe for long-term tracking and imaging in vivo, with good temporal and spatial resolution.

Luminescent nanodiamonds for biomedical applications

“…This vacancy enables them to carry a negative or neutral charge . A number of processing techniques have been developed to artificially create the NV centre in diamond, including nitrogen implantation (Kalish et al 1997) and electron (Dyer and Du Preez 1965) or ion (Chang et al 2008b) irradiation. In the context of bioimaging, the most noteworthy feature, of the more abundant, negatively charged NV centre is that it can be optically excited between 480 and 580 nm to emit a broad luminescence band centred at 690 nm ( Fig.…”

“…3) (Fu et al 2007;Chang et al 2008b;Zhang et al 2009a) more recently in real time (Faklaris et al 2009a) using single particle tracking within cells. As nanodiamonds do not enter the nucleus Chang et al 2008a, b;Wee et al 2009;Zhang et al 2009a) and because their bright fluorescence is emitted beyond the range of cellular autofluorescence Fu et al 2007;Fucikova et al 2009;Weng et al 2009), they can be used as cytoskeletal markers at concentrations as low as 1 μg/mL and detected using confocal fluorescence microscopy ).…”

“…17 ns) (Fu et al 2007) relative to cell auto-fluorescence, time-gated confocal imaging can also be used to enhance the nanodiamond signal (Faklaris et al 2008). Two-photon excitation microscopy can further improve resolution and contrast and minimise background noise (Chang et al 2008b).…”

“…The inherent difficulty with this technique is the low sensitivity of nuclear Reprinted by permission from Macmillan Publishers Ltd: Nature Nanotechnology (Chang et al 2008b(Chang et al ), copyright 2008 magnetism in combination with the low natural abundance of spin-active 13 C (1.1%) relative to 12 C. Methods to overcome this limitation include the production of nanodiamond grown from 13 C-rich sources and the use of nuclear hyperpolarisation (Hoch and Reynhardt 1988;Reynhardt and Terblanche 1997) which can dramatically increase the nuclear resonance signal.…”

“…They are used in many applications, including electrochemical coatings (Dolmatov 2006;Baidakova and Vul' 2007), polymer compositions (Akopyan et al 2004;Dolmatov 2006), polishing (Artemov 2004;Dolmatov 2006), and lubricants (Dolmatov 2006). More recently, they have been the subject of intense research in quantum optics (Kurtsiefer et al 2000), nanoscale magnetometry (Balasubramanian et al 2008;Maze et al 2008) and biomedical applications that range from drug delivery to intracellular tracking Pramatarova et al 2007;Chang et al 2008b;Liu et al 2008;Xing and Dai 2009;Yuan et al 2010). The biocompatibility, readily modifiable surface and optical properties originating from defects within their crystal lattice combine to make nanodiamonds extremely promising for use in biological environments.…”