A Comparative Photophysical Study of Structural Modifications of Thioflavin T-Inspired Fluorophores
- 22 September 2020
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry Letters
- Vol. 11 (19), 8406-8416
- https://doi.org/10.1021/acs.jpclett.0c01549
Abstract
The benzothiazolium salt, Thioflavin T (ThT), has been widely adopted as the ‘gold-standard’ fluorescent reporter of amyloid in vitro. Its properties as a molecular rotor result in a large-scale (~1000-fold) fluorescence turn-on upon binding to β-sheets in amyloidogenic proteins. However, the complex photophysics of ThT combined with the intricate and varied nature of the amyloid binding motif means these interactions are poorly understood. To study this important class of fluorophore, we present a detailed photophysical characterisation and comparison of a novel library of twelve ThT-inspired fluorescent probes for amyloid protein (PAPs), where both the charge and donor capacity of the heterocyclic and aminobenzene components have been interrogated, respectively. This enables direct photophysical juxtaposition of two structural groups; Class 1 the neutral ‘PAP’ and Class 2 the charged ‘mPAP’ fluorophores. We quantify binding and optical properties at both the bulk and single-aggregate levels with some derivatives showing higher aggregate affinity and brightness than ThT. Finally, we demonstrate their abilities to perform super-resolution imaging of α-synuclein fibrils with localisation precisions of ~16 nm. The properties of the derivatives provide new insights into the relationship between chemical structure and function of benzothiazole probes.Keywords
Funding Information
- Engineering and Physical Sciences Research Council
- Royal Society (UF120277)
- Michael J. Fox Foundation for Parkinson's Research
- National Institute of General Medical Sciences (R01GM121573)
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