[16p-2C-1~10] 4.2 Bio- and Medical Photonics

▲ [16p-2C-1] [JSAP-OSA Joint Symposia 2015 Invited Talk] Application of fluorescent diamond nanoparticles to bio-imaging

Ryuji Igarashi¹, Shingo Sotoma¹, Masahiro Shirakawa¹, 〇Yoshie Harada¹ (1.Kyoto Univ.)

Keywords:nitrogen vacancy center,diamond nanoparticle,optically detected magnetic resonance

Nitrogen vacancy centers (NVCs) in nanodiamonds have recently been attracting much attention as a new fluorescent probe. NVC is an atomic-sized defect paired with a nitrogen atom and the adjacent vacancy of a carbon atom in the diamond lattice. It is known that fluorescence from NVC-containing nanodiamonds is markedly stable in contrast to organic and semi-conducting fluorescent probes commonly used in cell and in vivo observations. A notable property is that the fluorescence from NVC is dependent on a spin degree of freedom in the ground states, and the fluorescence intensity can be manipulated by microwave (MW) irradiations in optically detected magnetic resonance (ODMR). By using this property, we reported a selective imaging method to completely eliminate extraneous fluorescence in real-time microscope observations, and demonstrated successful observations of nanodiamonds in a living HeLa cell, Caenorhabditis elegans, and a mouse. Furthermore, the NVC has also been attracted as an atomic-sized sensor to detect not only magnetic field but also electric field and temperature in the nanoscale region. Another pressing need in measuring dynamics in biology is the creation of an efficient tool to quantitatively detect rotational motions of an object in vivo. The ODMR spectrum of NVCs taken in the presence of magnetic field reveals the profile variations that strongly depends on an angle formed between an NVC principle axis and the magnetic field. Since the spectrum is sensitively affected even with a minute change in the angle (even by a few degrees), we expect that rotational motions of a nanodiamond can be quantitatively investigated in vivo, if the spectrum is measured with reference to specified magnetic orientations. Here, we introduce the observation of the rotary movement using diamond nanoparticles, including NV⁻ as fluorescent probes. This is a unique and unconventional method of measurement that is achieved through a combination of spin operative techniques, using fluorescence detection technology and magnetic resonance.