Recovery of Photoinduced Reversible Dark States Utilized for Molecular Diffusion Measurements
2010 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 82, no 24, 9998-10005 p.Article in journal (Refereed) Published
For a spatially restricted excitation volume, the effective modulation of the excitation in time is influenced by the passage times of the molecules through the excitation volume. By applying an additional time-modulated excitation, the buildup of photoinduced reversible dark states in fluorescent molecules can be made to vary significantly with their passage times through the excitation volume. The variations in the dark state populations are reflected by the time-averaged fluorescence intensity, which thus can be used to characterize the mobilities of the molecules. The concept was experimentally verified by measuring the fluorescence response of freely diffusing cyanine fluorophores (Cy5), undergoingtrans-cis isomerization when subject to time-modulated excitation in a focused laser beam. From the fluorescence response, and by applying a simple photodynamic model, the transition times of the Cy5 molecules could be well reproduced when applying different laminar flow speeds through the detection volume. The presented approach puts no constraints on sample concentration, no requirements for high time resolution or sensitivity in the detection, nor requires a high fluorescence brightness of the characterized molecules. This can make the concept useful for a broad range of biomolecular mobility studies.
Place, publisher, year, edition, pages
American Chemical Society (ACS), 2010. Vol. 82, no 24, 9998-10005 p.
Fluorescence correlation spectroscopy, FCS, isomerisation, transient states, diffusion
Physical Chemistry Biophysics
Research subject Biological Physics
IdentifiersURN: urn:nbn:se:kth:diva-12344DOI: 10.1021/ac1014047ISI: 000285215800006ScopusID: 2-s2.0-78650344728OAI: oai:DiVA.org:kth-12344DiVA: diva2:309816
FunderEU, FP7, Seventh Framework Programme, 201 837Swedish Research Council, VR-NT 2009-3134Knut and Alice Wallenberg Foundation
QC 20100617 Uppdaterad från manuskript till artikel (20110110). Tidigare titel: Recovery of Photo-Induced Reversible Dark States Utilized for Molecular Diffusion Measurements2010-04-122010-04-082016-03-10Bibliographically approved