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Regensburg 2004 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 16: POSTER: Computational Physics, Complex Systems

CPP 16.34: Poster

Tuesday, March 9, 2004, 17:00–19:00, B

Fluorescence Lifetime Investigations of DNA mediated Dye/Gold Nanoparticle Conjugates — •M. Ringler1, E. Dulkeith1, T. Niedereichholz1, T. A. Klar1, and J. Feldmann1, A. Munoz-Javier2, and W. J. Parak21Photonics and Optoelectronics Group, University of Munich — 2CeNS, University of Munich

Gold nanoparticles have been shown to be extremely efficient quenchers of luminescence from dye molecules attached to their surface [1]. In the present study we investigated how the quenching efficiency depends on the distance between the dye molecule and the nanoparticle using carbon chain spacers of different lengths. An increase of the fluorescence lifetime with spacer length is observed.
In a subsequent experiment we replaced the carbon spacers with single stranded oligonucleotides (ssDNA). We can spectroscopically determine the number of ssDNA bound to a nanoparticle. Varying the degree of ssDNA coverage we observe that the fluorescence lifetime becomes significantly longer when the number of ssDNA per nanoparticle is increased. This gives evidence that the conformation of DNA bound to gold nanoparticles changes from wrapped to stretched when the surface coverage is increased [2].
[1] E. Dulkeith et al., Phys. Rev. Lett. 89, 203002 (2002)
W. J. Parak et al., Nano Letters 3, 33-36 (2003)

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