A fluorescent probe for concurrent detection of cysteine, homocysteine, and superoxide anion

Redox imbalance is a key factor in the pathogenesis of diseases such as epilepsy and liver injury. Superoxide anion (O 2 •− ), cysteine (Cys), and homocysteine (Hcy) play central roles in maintaining redox homeostasis, and their dysregulation drives oxidative stress and disease progression. Here, we report a multifunctional fluorescent probe, BPC, capable of simultaneously and selectively detecting Cys, Hcy, and O 2 •− in complex biological environments. BPC shows high sensitivity, selectivity, and biocompatibility, enabling real-time visualization of redox fluctuations in living cells and zebrafish with minimal cytotoxicity. In pentylenetetrazole (PTZ)– and acetaminophen (APAP)–induced models of epilepsy and liver injury, BPC revealed notable alterations in Cys, Hcy, and O 2 •− levels, providing mechanistic insights into redox dysregulation. Moreover, BPC successfully tracked redox restoration following N -acetylcysteine (NAC) treatment. These findings establish BPC as a versatile tool for redox biology and highlight its promise for diagnostic and therapeutic applications.