Excited-state intramolecular proton transfer (ESIPT)-based fluorophores with two-photon excitation fluorescence (TPEF) are rare. Our aim with this research was to develop ESIPT-based fluorophores exhibiting TPEF. Herein, we used 4-hydroxyisoindoline-1,3-dione as a scaffold to develop a two-photon fluorescent probe BHID-Bpin, for the detection of peroxynitrite (ONOO-). BHID-Bpin exhibits excellent selectivity, sensitivity, and fast response towards ONOO- in PBS buffer solution (10 mM, pH = 7.40). Additionally, BHID-Bpin displays high photo-stability under two-photon irradiation at 750 nm. Furthermore, the probe can image endogenous ONOO- in HeLa cells and exogenous ONOO- in rat hippocampal slices at a depth of 110 μm.
LW wishes to thank China Scholarship Council and the University of Bath for supporting his PhD work in the UK. XT wishes to thank the University of Bath for supporting her PhD work in the UK. We would like to thank the EPSRC and the University of Bath for funding. DJL, CSL and HMK thank the National Leading Research Lab Program of the National Research Foundation of Korea (NRF), funded by the Korean government (MSIP) (NRF-2019R1A2B5B03100278, NRF-2021R1C1C1013187), Center for Convergence Research of Neurological Disorders (NRF-2019R1A5A2026045). TDJ wishes to thank the Royal Society for a Wolfson Research Merit Award and the Open Research Fund of the School of Chemistry and Chemical Engineering, Henan Normal University for support (2020ZD01). NMR and Mass Spectroscopic (MS) Characterisation facilities were provided by the Material and Chemical Characterisation Facility (MC2) at the University of Bath (http://go.bath.ac.uk/mc2). All data supporting this study are provided as ESI\u2020 accompanying this paper.
