Simultaneous detection and speciation of mono- & di-valent copper ions with a dual-channel fluorescent nanoprobe

Redox cyclings between mono-/di-valent copper oxidation states occur in electron transfer reactions that underlie their biological functions. We report herein a dual channel fluorescent nanoprobe for the detection of mono- and di-valent copper ions. The probe, BSA-CDs@RBH/BCS, is designed by decorating carbon dots (CDs) on BSA encapsulated rhodamine hydrazide (RBH) and conjugating with bathocuproine disulfonate (BCS). Cu2+ catalyzes the hydrolysis of RBH, and the formed rhodamine B (RhB) shows emission at λex/λem = 360/575 nm which ensures Cu2+ detection. BSA reduces Cu2+ to Cu+ and the BCS-Cu+ chelate shows emission at λex/λem 360/450 nm which ensures Cu+ assay. Thus, the dual-channel fluorescence enables speciation of Cu2+ and Cu+.