A two-photon off-on fluorescence probe for imaging thiols in live cells and tissues

Abstract

A two-photon (TP) fluorescence imaging probe (Z1) was designed to detect biothiols through a photoinduced electron transfer pathway utilizing N-butyl-naphthalimide as the fluorophore and 2,4-dinitrobenzene-sulfonyl as the responsive group, which were linked together by piperazine. The synthesized Z1 displayed high selectivity to biothiols, significant fluorescence off–on properties, and a marked two-photon absorption cross section (δ = 110 GM). Moreover, Z1 showed good biocompatibility and insensitivity toward changes in the biologically relevant pH range (7.2–8.4), which enabled the utilization of Z1 to monitor biothiol levels not only in live cells but also in tissues at depths of 50–250 μm.