Dark states in ionic oligothiophene bioprobes-evidence from fluorescence correlation spectroscopy and dynamic light scattering
2014 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 118, no 22, 5924--5933 p.Article in journal (Refereed) Published
Luminescent conjugated polyelectrolytes (LCPs) can upon interaction with biological macromolecules change their luminescent properties, and thereby serve as conformation- and interaction-sensitive biomolecular probes. However, to exploit this in a more quantitative manner, there is a need to better understand the photophysical processes involved. We report studies of the conjugated pentameric oligothiophene, derivative p-FTAA, which changes optical properties with different p-FTAA concentrations in aqueous buffers, and in a pH and oxygen saturation dependent manner. Using dynamic light scattering, luminescence spectroscopy and fluorescence correlation spectroscopy, we find evidence for a monomer dimer equilibrium, for the formation of large clusters of p-FTAA in aqueous environment, and can couple aggregation to changed emission properties of oligothiophenes. In addition, we observe the presence of at least two dark transient states, one presumably being a triplet state. Oxygen was found to statically quench the p-FTAA fluorescence but also to promote molecular fluorescence by quenching dark transient states of the p-FTAA molecules. Taken together, this study provides knowledge of fluorescence and photophysical features essential for applying p-FTAA and other oligothiophene derivatives for diagnostic purposes, including detection and staining of amyloid aggregates.
Place, publisher, year, edition, pages
American Chemical Society (ACS), 2014. Vol. 118, no 22, 5924--5933 p.
FCS, FLUORESCENCE, CONJUGATED POLYMERS; POLYTHIOPHENE; DNA; AMYLOIDOSES; DERIVATIVES; ASSEMBLIES; SYSTEMS
Research subject Biological Physics
IdentifiersURN: urn:nbn:se:kth:diva-144060DOI: 10.1021/jp501324eISI: 000337011400013ScopusID: 2-s2.0-84901982083OAI: oai:DiVA.org:kth-144060DiVA: diva2:710747
FunderKnut and Alice Wallenberg Foundation, KAW 2011.0218Swedish Research Council, VR-NT, 2012-3045
Updated from "Manuscript" to "Published article". QC 201407072014-04-082014-04-082016-03-10Bibliographically approved