Regensburg 2007 – scientific programme

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BP: Fachverband Biologische Physik

BP 18: Functionalized Nanoparticles

BP 18.2: Talk

Wednesday, March 28, 2007, 14:15–14:30, H43

Nanodiamonds as Photostable Fluorophoric Lable in Living Cells — •Felix Neugart, Carsten Tietz, Fedor Jelezko, and Jörg Wrachtrup — 3. Physical Institute, Pfaffenwaldring 57, University of Stuttgart, 70550 Stuttgart

Many processes in living cells could be promoted by investigation on a single molecule level such as single particle tracking. Dye molecules, especially auto fluorescent proteins, are limited by photobleaching, semiconductor quantum dots are toxic for cells. Nanodiamonds are non-toxic and show a bright non bleaching fluorescence. The origin of the fluorescence are colour centres, these are defects in the diamond lattice. The surface can be functionalized to bind to proteins or other particles of interest. With a size of down to 5 nm nanodiamonds are comparatively small. For our experiments we prepared diamonds (50 nm and 125 nm crystallites) with NV-centres emitting around 700 nm where living cells show a low autofluorescence. Defects at the surface of the nanodiamonds cause aggregation of the diamonds in physiological buffer solutions. To clean the surface of the nanodiamonds from graphite and other impurities the crystallites were penetrated by strong acids. Acid treated nanodiamonds stay in the buffer in stable colloidal solution. We inserted the nanodiamonds into cells by microinjection or by endocytosis. The diamonds could be detected by fluorescence as well as refraction.