Regensburg 2004 – wissenschaftliches Programm

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SYLS: Life Sciences on the Nanometer Scale - Physics Meets Biology

SYLS 2: Symposium "Life Sciences on the Nanometer Scale - Physics Meets Biology"

SYLS 2.3: Vortrag

Mittwoch, 10. März 2004, 15:45–16:00, H 37

Detection and spectroscopy of 5 nm gold particles using white-light confocal microscopy — •Patrick Stoller¹, Klas Lindfors², Thomas Kalkbrenner³, and Vahid Sandoghdar¹ — ¹Physical Chemistry Laboratory; Swiss Federal Institute of Technology (ETH); CH-8093, Zurich; Switzerland — ²Department of Physics; Helsinki University of Technology; P. O. Box 1000; FIN-02015 HUT; Finland — ³FOM Institute for Atomic and Molecular Physics (AMOLF); Kruislaan 407; 1098 SJ Amsterdam; The Netherlands

The interaction of fluorescently labeled biological molecules can be observed dynamically using optical microscopy. Gold nanoparticles can also be used to optically label biological molecules because of their well-defined plasmon resonance spectrum. Gold nanoparticles are biocompatible and, unlike fluorophores, they do not bleach. To avoid interference with the molecular interaction, it is important to minimize the size of the labels. Recently, Boyer et. al. succeeded in detecting 2.5 nm gold nanoparticles using photothermal imaging [Science. 297. 1160-1163]. In our work, we used white light confocal microscopy not only to detect but also to observe the plasmon resonance spectrum of single gold nanoparticles with diameters as small as 5 nm [submitted]. An ultra-short pulse laser and a photonic crystal fiber were used to generate a collimated beam of quasi-continuum white light, which was tightly focused onto the sample using a high numerical aperture microscope objective; the scattered light was collected confocally and detected using an imaging spectrometer. Our goal is to apply this technique to studying the interaction of biological molecules at the single molecule level.