Structural, optical and plasmonic sensing characteristics of graphene quantum dots/gold nanolayered film in contact with dopamine solution

Graphene quantum dots (GQDs) have captured a considerable attention in biomedical field due to their unique structure-related properties. In this work, GQDs monolayer film was coated on gold thin film and integrated into surface plasmon resonance spectroscopy (SPR). The plasmonic sensing properties of GQDs/Au nanostructured layer in contact with varied concentrations of dopamine (DA) solution were evaluated. Increasing DA concentrations increased the changes in the resonance angle. This sensing platform showed a good sensitivity of 0.332°/nM throughout a linear range of 0.01–100 nM, as well as a high binding affinity of 1.610 × 10 9 M −1 . The optical properties of GQDs film were precisely determined by fitting the experimental curves to theoretical data formula using the transfer matrix method (TMM). The fitting results showed that the n value of the GQDs film was 1.3049 and its thickness was 7.22 nm in the absence of DA solution. The binding of DA to the SPR chip, as evidenced by the structural analysis of the film using FTIR and AFM, increased the n value and thickness of the GQDs film. These findings revealed the obvious changes in the structural and optical characteristics of this GQDs film after interaction with DA, and confirmed the potential of this material in DA sensing when combined with SPR spectroscopy.