Photoexcitation induces translocation of a common fluorescent pH and proton-transfer probe confined in reverse micelles.

Authors

Gerardo A Virgen, Sulejman Skoko, Ashley M Stingel, Tanmay Goswami, Richard L Cole, Debbie C Crans, Poul B Petersen, Ana Vila Verde, Nancy E Levinger

Published in

Proceedings of the National Academy of Sciences of the United States of America. Volume 123. Issue 25. Pages e2518988123. Jun 23, 2026. Epub Jun 18, 2026.

Abstract

The photoacid 8-hydroxypyrene-1,3,6-trisulfonate (HPTS) is one of the most widely used fluorescent probes for studying proton transfer and local pH in systems from advanced materials to plants, environmental sensors to medicine. HPTS exists as two different species: the acid and its conjugate base, which lead to unique protonation-state-dependent translocation of the molecule when it is nanoconfined within anionic AOT reverse micelles. Using steady-state and time-resolved optical spectroscopy, molecular simulations, and IR solvation shell spectroscopy, we report that the protonated HPTS species associates strongly with the micelle interface via hydrogen bonding. In contrast, its deprotonated species resides in the micelle's aqueous interior. Our results show that photoexcitation of the acid species and its subsequent deprotonation leads the conjugate base to rapidly move away from the interface into the water pool. This light-induced translocation, an effect observed for a range of micelle sizes, challenges the prevailing view where molecular probes are assumed to be static reporters of their environments, remaining in a fixed location for the duration of an experiment. This is especially relevant for interpreting results in the numerous studies enlisting optical spectroscopy of HPTS to report on complex systems. Our findings reveal the potential for molecular probes as dynamic explorers capable of mapping environmental heterogeneity on the timescale of the very processes they are designed to measure.

PMID:
42313936
Bibliographic data and abstract were imported from PubMed on 19 Jun 2026.

Read full publication at:
Please sign in to see all details.

Stats

1-terrible, 9-excellent. How would you rate this publication? Sign in in to submit your rating.

Post a comment

You need to be signed in to post comments. You can sign in here.

Comments

There are no comments yet.