Fluorene-naphthalimide hybrid: An electrochemical and fluorescent probe for detection and imaging of hydrogen sulfide dynamics in cellular environments

Document Type

Article

Publication Title

Microchemical Journal

Abstract

The detection of hydrogen sulfide (H2S) in human cells is vital due to its function as a biological signaling molecule and involvement in diverse physiological and pathological processes. In this context, a new fluorene-nitronaphthalimide hybrid derivative (FNN) was synthesized by appending 2-amino fluorene to 4-nitro-1,8-naphthalic anhydride through an easy one-step imidation reaction. Theoretical study showed strong planarity and intramolecular charge transfer (ICT) due to the electron-withdrawing –NO2 group in FNN, which shifts upon reduction to an electron-donating –NH2 group causing structural distortion, reduced ICT, a widened HOMO–LUMO gap, and higher selectivity toward H2S over CO. Electrochemical and spectroscopic analyses revealed pH-dependent redox activity of FNN with a strong response to H2S, achieving a low detection limit of 12.15 nM at physiological pH. XPS and SEM studies confirmed sulfur incorporation on the electrode surface, validating the detection mechanism and highlighting the potential of FNN as a highly sensitive electrochemical probe for H2S. Fluorescence measurements established 14 mM as the detection limit, and FNN was subsequently utilized as a fluorescent probe to image H2S dynamics in cell cultures under both normal and stress-induced conditions. The probe exhibited a significant increase in fluorescence intensity in nutrient-limiting media compared to complete media, even without the addition of external H2S. This enhanced response is linked to autophagy-induced changes in redox homeostasis and stimulation of endogenous H2S biosynthesis through H2S-producing enzymes in response to nutrient-deprivation conditions. Thus, dual electrochemical and fluorescence-based detection capability of FNN provides a more robust and versatile approach for monitoring H2S in diverse environments, from electrolyte solutions to live-cell imaging to monitor cellular dynamics, autophagy-related processes, and the role of H2S in physiological and pathophysiological conditions.

DOI

10.1016/j.microc.2025.114060

Publication Date

8-1-2025

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