An ESIPT Probe for the Ratiometric Imaging of Peroxynitrite Facilitated by Binding to Aβ-Aggregates.

A series of 3-hydroxyflavone (3-HF) ESIPT (excited-state intramolecular proton transfer) boronate-based fluorescent probes have been developed for the detection of peroxynitrite (ONOO-). The dyes are environmentally sensitive, and each probe exhibited a ratiometric response toward ONOO- in a micellar environment. The probes were used to image different aggregation states of amyloid-β (Aβ) in the presence of ONOO-. The 3-HF-OMe probe was found to produce a ratiometric response toward ONOO- when bound to Aβ aggregates, resulting in a novel host-guest ensemble, which adds insight into the development of other ESIPT-based probes for the simultaneous sensing of fibrous proteins/peptides and environmental ROS/RNS.