Fluorescent probe based on GO/g-C₃N₄-PEG@Cu NPs/MIP for the detection of dopamine in banana

Graphene oxide (GO) and copper nanoparticles (Cu NPs) were incorporated to modulate and enhance the fluorescence properties of pegylated graphite phase carbon nitride (g-C₃N₄-PEG). Combined with the specific recognition capability of a molecular imprinted polymer (MIP), a highly sensitive and selective fluorescent molecular imprinted probe for dopamine detection was developed. The fluorescent g-C₃N₄-PEG was synthesized from melamine and modified with GO and Cu NPs to obtain GO/g-C₃N₄-PEG@Cu NPs. Subsequently, MIP was prepared on the surface of GO/g-C₃N₄-PEG@Cu NPs using dopamine as the template molecule. Upon elution of the template molecule, a dopamine-specific GO/g-C₃N₄-PEG@Cu NPs/MIP fluorescence probe was obtained. The fluorescence intensity of the probe was quenched through the adsorption of different concentrations of dopamine by the MIP, thus establishing a novel method for the detection of dopamine. The linear range of dopamine detection was from 5 × 10^-11 to 6 × 10^-8 mol L^-1, with a detection limit of 2.32 × 10^-11 mol L^-1. The sensor was utilised for the detection of dopamine in bananas, achieving a spiked recovery rate between 90.3% and 101.3%. These results demonstrate that the fluorescence molecular imprinted sensor developed in this study offers a highly sensitive approach for dopamine detection in bananas.