Cyclobutylamino-naphthalimide-based fluorescent probe for detection of glutathione in living cells

Abstract

Fluorophores that incorporate cyclobutylamine auxochromes exhibit improved quantum yields, photostability, biocompatibility, and cell permeability. In this study, we present the design and synthesis of a novel ratiometric probe (NAPB) based on cyclobutylamino-naphthalimide (NCB), which enables the selective and sensitive detection of glutathione (GSH). NAPB employs a nucleophilic substitution/cyclization strategy to detect GSH. In the presence of GSH, a noticeable ratiometric change in the emission wavelength occurs, shifting from blue to greenish-yellow fluorescence. The probe can detect GSH rapidly, with a detection limit as low as 39.1 nM. Following confirmation of biosafety through an MTT assay, NAPB was further utilised for fluorescence imaging of GSH in live HepG2 cells. © 2025 Elsevier B.V.