An isophorone-derived AIE-active probe for peroxynitrite detection and bioimaging applications

Compounds exhibiting aggregation-induced emission (AIE) are remarkable due to their characteristic restriction of intramolecular rotation, making them highly versatile for a wide range of applications. Herein, an isophorone based probe (IHP) was developed for the detection of peroxynitrite (ONOO^-) using the C[double bond, length as m-dash]N as the reactive group. Photophysical investigations were conducted to explore the aggregation behaviour of IHP in two different solvent systems: DMSO:PBS and DMSO. In DMSO, only the monomeric form of the dye was observed, showing no unusual behaviour. However, in DMSO : PBS (1 : 1), multiple emitting species were detected, indicating the coexistence of dye aggregates and monomers. The fluorescence spectra exhibited wavelength-dependent changes, with the aggregates displaying a red-shift compared to the monomers, indicating J-aggregation. The AIE properties of IHP resulted in red emission, with a fluorescence response towards ONOO^- through oxidative cleavage of the C[double bond, length as m-dash]N bond to an aldehyde accompanied by the shift in emission maximum. Under physiological conditions, the probe exhibited good selectivity and high sensitivity to ONOO^-, low detection limit of 1.1 μM and rapid recognition within 200 seconds. Furthermore, the probe was effectively used to image exogenous and endogenous peroxynitrite in living cells.