A ratiometric fluorometric epinephrine and norepinephrine assay based on carbon dot and CdTe quantum dots nanocomposites

A ratiometric fluorescence nanoprobe, consisted of water-soluble fluorescent carbon dots (CDs) and 3-mercapropionic acid-coated cadmium telluride quantum dots (CdTe QDs), was constructed for the detection of epinephrine (EP) and norepinephrine (NE). Under single-wavelength excitation (370 nm), the hybrid nanoprobe possessed dual emission peaks at 460 and 610 nm belongs to CDs and CdTe QDs, respectively. CdTe QDs fluorescence was quenched by EP or NE via electron transfer from QDs to the oxidation products of catecholamines, while the fluorescence intensity of CDs remained almost constant, which provided a ratiometric fluorescence assay for the catecholamines detection. The relative fluorescence intensity ratios were directly proportional to the concentration of catecholamines. Meanwhile, some structural analogues of the target molecules, including dopamine hydrochloride and isoprenaline hydrochloride, had no significant interference for the detection mode. The novel fluorescence detection platform was rapid and convenient, and applied to the detection of EP and NE in human serum samples with satisfactory results.