Dresden 2009 – scientific programme
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BP: Fachverband Biologische Physik
BP 7: Poster I
BP 7.44: Poster
Monday, March 23, 2009, 17:45–20:00, P3
Competitive Homogeneous Hapten Immunoassay Based on Fluorescence Quenching by Gold Nanoparticles — Benjamin Ehlers1, Sergiy Mayilo1, •Meike Kloster1, Michael Wunderlich1, Thomas A. Klar1,2, Hans-Peter Josel3, Dieter Heindl3, Alfons Nichtl3, Konrad Kürzinger3, and Jochen Feldmann1 — 1Photonics and Optoelectronics Group, Department of Physics and CeNS, Ludwig-Maximilians-Universität München, Munich, Germany — 2Institute of Physics and Institute of Micro- and Nanotechnologies, Technical University of Ilmenau, Ilmenau, Germany — 3Roche Diagnostics GmbH, Penzberg, Germany
We report on a competitive, homogeneous immunoassay for the detection of the hapten digoxigenin, a drug used to cure atrial fibrillation. The assay consists of gold nanoparticles functionalized with anti-digoxigenin antibodies and fluorescently labelled digoxigenin. Initially, the labelled digoxigenin is bound to the gold nanoparticles and the fluorescence is effectively quenched. Upon the addition of digoxigenin, a competition takes place for the antibodies on the gold nanoparticles leading to labelled digoxigenin free in solution and therefore an increase of fluorescence. By using time-resolved spectroscopy, it is found that the quenching is due to energy transfer from the dye to the gold nanoparticle. The assay is sensitive in the therapeutically relevant concentration range of 0.5 to 3 ng/mL. The method can be applied both in buffer solution and in serum. The same principle of competitive fluorescence quenching can be applied to detect other haptens.