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Proceedings Paper

Biosensing and -imaging with enantiomeric luminescent conjugated polythiophenes using multiphoton excitation
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Paper Abstract

We report on the initial time-resolved luminescense and nonlinear absorption properties of two polythiophenes 3-substituted with chiral charged amino acid-derivatized substituents, POWT and POMT. The photo-physical characterization yielded quantum efficiency typically in the range 0.01 - 0.1, however, with two-photon absorption cross-section better than or similar to a typical two-photon reference chromophore, such as fluorescein. They were tested as conformational sensitive optical probes for the recording of pH-induced conformational changes of synthetic peptides, proteins and samples of protein amyloid fibrils characteristic of amyloid related diseases. Particularly, the POMT polyelectrolyte with the L-enantiomeric side chains is shown to favor this induction of well defined structure as judged by the circular dichroic signal as well as a stronger enhancement of luminescense for the L-form over the D-form complex. Furthermore, time-resolved fluorescense and two-photon induced fluorescence both also showed a difference in the complexation with the D and L form. This shows that the multi-photon excitation path can be an efficient means for chiral recognition of biomolecular complexes. It is demonstrated how the conjugated polyelectrolyte L-POMT can be used to spectrally image the formation of amyloid fibrils of insulin using both one- and two-photon absorption based fluorescence imaging.

Paper Details

Date Published: 18 August 2005
PDF: 10 pages
Proc. SPIE 5935, Linear and Nonlinear Optics of Organic Materials V, 59350E (18 August 2005); doi: 10.1117/12.624438
Show Author Affiliations
Mikael Lindgren, The Norwegian Univ. of Science and Technology (Norway)
Frantz Stabo-Eeg, The Norwegian Univ. of Science and Technology (Norway)
Edrun A. Schnell, The Norwegian Univ. of Science and Technology (Norway)
K. Peter R. Nilsson, Linkopings Univ. (Sweden)
Per Hammarstrom, Linkopings Univ. (Sweden)
Olle Inganaes, Linkopings Univ. (Sweden)

Published in SPIE Proceedings Vol. 5935:
Linear and Nonlinear Optics of Organic Materials V
Manfred Eich, Editor(s)

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