Determination of dopamine by a label-free fluorescent aptasensor based on AuNPs and carbon quantum dots

Abstract

In order to reduce the complex modification process and obtain a fast and label-free aptasensor, a label-free fluorescent aptasensor based on gold nanoparticles (AuNPs) and carbon quantum dots (CQDs) was constructed for rapid determination of dopamine (DA). In the absence of DA, CQDs were adsorbed on the surface of AuNPs through the electrostatic force between CQDs and aptamer, which led to the fluorescence quenching of CQDs. When DA were added, they combined with the corresponding aptamers with higher affinity and selectivity, resulting in CQDs far from the surface of AuNPs and thus the fluorescence intensity of CQDs was recovered. Under the optimal condition, the fluorescence intensity of the released CQDs was linearly proportional to the concentration of DA in a range of 5×10-8˜2.5×10-4mol/L with a detection limit of 1×10-8mol/L. Moreover, the aptasensor exhibited a satisfactory detection result of DA in human serum samples. This study provided a more effective method to detect a broad range of targets by using appropriate aptamers, holding great potential in the field of food safety and biomedical diagnostics.