Simultaneous Visualization of Glutathione and Hydrogen Peroxide with a Dual-Responsive Fluorescent Probe to Elucidate Redox Homeostasis in Alzheimer's Disease Models.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder in which oxidative stress plays a critical role in pathogenesis. As key reactive species governing oxidative stress, the dynamic interplay between glutathione (GSH) and hydrogen peroxide (H2O2) is tightly coupled to redox homeostasis. To enable simultaneous tracking of these two crucial species, we developed a dual-responsive fluorescent probe, TCS, for the discriminative visualization of GSH and H2O2. TCS features a methylsulfonyl group that is selectively reduced by GSH, triggering green fluorescence at 500 nm, and a boronate ester that is specifically cleaved by H2O2, generating red emission at 680 nm. These two optical channels operate independently with minimal spectral overlap, enabling simultaneous and discriminative detection of GSH and H2O2 without cross-interference. Probe TCS exhibits high sensitivity, excellent selectivity, and good photostability, and is well-suited for real-time imaging of both endogenous and exogenous GSH and H2O2 in complex biosystems. In okadaic acid-induced AD cell and zebrafish models, TCS revealed a time-dependent decrease in GSH levels accompanied by a concomitant increase in H2O2, consistent with progressive oxidative stress. Furthermore, comparative imaging of hippocampal tissues from AD model mice and wild-type mice showed markedly altered levels of both species, underscoring the utility of TCS for visualizing redox imbalance under AD-like pathological conditions. Collectively, this study establishes TCS as a powerful molecular tool for spatiotemporally resolved monitoring of GSH and H2O2 dynamics in living systems and provides a robust analytical platform for elucidating redox mechanisms in AD.