Rapid-Response and Highly Sensitive Boronate Derivative-Based Fluorescence Probe for Detecting H₂O₂ in Living Cells

Intracellular H₂O₂ monitoring is important and has driven researchers to pursue advancements for the rapid identification of H₂O₂, since H₂O₂ is short-lived in cell lines. An arylboronate derivative has been investigated as a chemospecific fluorescence recognition agent for H₂O₂. Triphenylimidazoleoxadiazolephenyl (TPIOP) boronate was contrived as a novel candidate for the rapid and sensitive recognition of H₂O₂. The probe was conjugated using the TPIOP functional group acting as an excellent fluorescent enhancer. The TPIOP group stimulated the polarization of C-B bond due to its extended π-conjugation, which included heteroatoms, and induced the production of rapid signal because of the highly polar C-B bond along with the corresponding boronate unit. While H₂O₂ reacts with TPIOP boronate, its nucleophilic addition to the boron generates a charged tetrahedral boronate complex, and then the C-B bond migrates toward one of the electrophilic peroxide oxygen atoms. The resulting boronate ester is then hydrolyzed by water into a phenol, which significantly enhances fluorescence through aggregation-induced emission. The TPIOP boronate probe responded to H₂O₂ rapidly, within 2 min, and exhibited high sensitivity with a limit of detection of 8 nM and a 1000-fold selectivity in the presence of other reactive oxygen species. Therefore, the developed TPIOP boronate chemodosimeter was successfully utilized to visualize and quantify intracellular H₂O₂ from human breast cancer (MCF-7) cells, as well as gaseous and aqueous H₂O₂ from environmental samples using Whatman paper strips coated with TPIOP boronate.