Graphene quantum dots and Nafion composite as an ultrasensitive electrochemical sensor for the detection of dopamine

A novel electrochemical sensor for highly sensitive and selective detection of dopamine (DA) was developed based on a graphene quantum dots (GQDs) and Nafion composite modified glassy carbon electrode (GCE). GQDs were synthesized by a hydrothermal approach for cutting graphene sheets into GQDs and characterized by TEM, UV-vis, photoluminescence, and FT-IR spectra. The GQDs had carboxyl groups with a negative charge, which not only provided good stability, but also enabled interaction with amine functional groups in DA through electrostatic interaction to enhance the specificity of DA. The interaction and electron communication between GQDs and DA can be further strengthened via p-p stacking force. Nafion was used as an anchoring agent to increase the robustness of GQDs on the electrode surface and sensor stability and reproducibility. The GQDs-Nafion composite exhibits a good linear range of 5 nM to 100 mM and a limit of detection as low as 0.45 nM in the detection of DA. The proposed electrochemical sensor also displays good selectivity and high stability and could be used for the determination of DA in real samples with satisfactory results. The present study provides a powerful avenue for the design of an ultrasensitive detection method for clinical application.