Enhancing probe's sensitivity for peroxynitrite through alkoxy modification of dicyanovinylchromene.

An intramolecular charge transfer (ICT)-based fluorescent probe P-ONOO was synthesized to detect ONOO. After responding to peroxynitrite, the dicyano-vinyl group of P-ONOO generates the aldehyde group, emitting strong green fluorescence accompanied by quenching of the yellow fluorescence. According to the calculated Fukui function, the modification of the alkoxy group can enhance the f of P-ONOO, which can enhance the probe's nucleophilic addition reactivity with ONOO. It has been experimentally verified that P-ONOO shows fast response (within 30 s), excellent sensitivity (the detection limit = 10.4 nM), and good selectivity towards ONOO. Additionally, the probe P-ONOO has high membrane permeability and good biocompatibility, which can image endogenous ONOO and exogenous ONOO in HeLa cells.