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.