A Donor-π-acceptor Fluorescent Probe for Hydrogen Peroxide Monitoring Reveals Oxidative Imbalance and Mitochondrial Damage Caused by Cd/Hg Exposure

Abstract

Heavy metal ions trigger hydrogen peroxide (H2O2) outbreak and sustained toxic damage, while current H2O2 fluorescent probes still suffer from critical limitations in revealing long-term oxidative stress under cadmium ion (Cd2+) and mercury ion (Hg2+) co-exposure, and are limited by narrow Stokes shift, insufficient sensitivity. Herein, an original donor-π-acceptor (D-π-A) push-pull electron visualized imaging fluorescence probe TQ-H2O2 was designed for clarifying the vague relationship between Cd2+/Hg2+-triggered up-regulated H2O2 breakout, oxidative imbalance and cellular damage explicitly. Intrinsic fluorescence quenching was broken and intramolecular charge transfer (ICT) mechanism restored upon addition of H2O2. The probe affords splendid responsive performance including large Stokes shift (119 nm), excellent sensitivity (LOD = 86.6 nM), distinctive specificity and decent biosecurity. TQ-H2O2 was employed to observe exogenous and endogenous H2O2 level fluctuation in RAW264.7, HepG2 cells, zebrafish, and provided visualization proof for Cd2+/Hg2+-mediated H2O2 variations imaging at the cellular level after separating from exposure. And the attenuation of mitochondrial membrane potential (MMP) and the degree of cell damage under variant stimulation of Cd2+/Hg2+ were evaluated. This work establishes a reliable analytical method for visualizing H2O2 dynamics and clarifying the causal link between heavy metal-induced oxidative stress, mitochondrial dysfunction, and cellular damage, providing a powerful tool for environmental toxicology and risk assessment.