A new selective fluorescence probe with a quinoxalinone structure (QP-1) for cysteine and its application in live-cell imaging.

A new selective probe with a quinoxalinone structure, QP-1, has been developed for detection of Cys from biothiols. QP-1 features superb selectivity to Cys and a wide pH range. QP-1 has selectivity to Cys over Hcy, GSH, other amino acids and ions. HRMS spectra confirmed that the detection process was a conjugate addition-addition-elimination reaction. Moreover, QP-1 has been successfully applied in the imaging of Cys in living cells. Finally, QP-1 has been used to detect Cys in rat urine samples.