Carbon Dot Fluorescent Nanoprobe for Dual-Channel Detection of Epinephrine and Pyrophosphate in Live Cells

Advanced dual-channel fluorescent probes for simultaneous biomarker detection are in critical demand nowadays in biomedical research. Herein, a blue-green emissive ratiometric probe CD@Tb has been engineered by coupling pyridinedicarboxylate-functionalized carbon dots (CD) with Tb³⁺ ions. This probe exhibits ultrasensitive and selective detection of epinephrine (EP, LOD: 1.2 nM) and pyrophosphate (PPi, LOD: 0.25 μM) via distinct fluorescence responses: Epinephrine (EP) enhances the blue emission while suppressing the green emission by deactivating the excited state of terbium through energy transfer. In contrast, pyrophosphate (PPi) amplifies the green emission of terbium through bridging coordination by inducing carbon dot aggregation, which strengthens the antenna effect, while simultaneously diminishing the blue emission. The sensing efficiency of the probe was tested in real human blood serum samples to check its reliability. Moreover, after thorough testing of its biocompatibility, the CD@Tb probe was employed as an imaging tool for visualization of epinephrine in human neuroblastoma cells, SH-SY5Y, and pyrophosphate in mouse fibroblast cells, NIH 3T3.