Fluorescent Biosensor for Rapid and Accurate Detection of Dopamine Based on Oxidized Single-Walled Carbon Nanohorns and Cryonase Enzyme.

In this study, a novel and sensitive fluorescent sensing platform was rationally developed for the rapid and specific detection of dopamine. The proposed strategy ingeniously integrates the superior adsorption behavior and extraordinary fluorescence quenching effect of oxidized single-walled carbon nanohorns toward FAM-modified aptamers, as well as the highly efficient cleavage property of the cryonase enzyme. Specifically, the fluorescently labeled aptamer is efficiently adsorbed and shielded by oxidized single-walled carbon nanohorns through strong supramolecular interactions, thereby triggering an evident fluorescence quenching response. Upon the introduction of target dopamine, the specific recognition event between dopamine and its corresponding aptamer takes place, accompanied by the formation of stable aptamer-dopamine complexes. Subsequently, these complexes are selectively hydrolyzed under the catalytic action of the cryonase enzyme, which contributes to the distinct release of fluorophores and the obvious recovery of fluorescence signals. Under the optimized experimental conditions, the aptamer exhibits good linearity toward dopamine in the concentration range of 50-400 ng/mL, with a correlation coefficient of 0.9957 and a low detection limit of 26.12 ng/mL. Therefore, the established analytical method offers a rapid, convenient, and reliable tool for the accurate determination of dopamine in complex human serum samples.