Designing enhanced and ratiometric probes for detecting OCl− based on substituents influencing the fluorescence of HBT and their application in strips and bioimaging

Abstract

Nitro groups with a strong electron-withdrawing effect can powerfully influence the fluorescence of fluorophores. In this work, through adjusting the nitro group at the HBT fluorophore to construct a phenylhydrazone structure, two probes (HBTN and HBTH) were synthesized to detect OCl⁻. Consequently, HBTN with the nitro group quenched the fluorescence of HBT and HBTH without the nitro group causing a redshift of the fluorescence, which resulted in enhanced and ratiometric fluorescence signal changes during the detection process. Among them, HBTN shows good ability to selectively detect OCl⁻ in the concentration range of 0–14 μM with the detection limit of 2.06 nM. Based on HBTN, a portable test strip for detecting OCl⁻ was made for the convenient quantification of the OCl⁻ concentration with a spectrophotometer, and exogenous and endogenous OCl⁻ was successfully imaged in cells.