Microplasma-enabled carbon dots composited with multi-walled carbon nanotubes for dopamine detection.

Composited carbon nanomaterials have attracted wide attention and are used for high-sensitivity biological assays due to their low toxicity, good biocompatibility, and excellent electrical conductivity. To further promote electron transfer and enhance electrocatalytic activity to detect dopamine (DA), this study proposed carbon dots (CDs) based on glycerol synthesized by liquid dielectric barrier discharge (DBD) microplasma. Combined with the multi-walled carbon nanotubes (MWCNTs) with excellent electrical conductivity, a composited carbon nanomaterial electrode of CDs/MWCNTs was constructed. As a DA biosensor, the interaction and electron exchange between MWCNTs, CDs, and DA can be enhanced thanks to the π-π stacking force, thereby facilitating the sensitive electrochemical detection of DA. The sensor exhibits good sensing performance toward DA detection with a linear range of 2.0-100 μM, a limit of detection (LOD) of 11.08 nM (S/N = 3), and a sensitivity of 29020 μA cm mM. The proposed electrode successfully detected DA levels in human serum samples with satisfactory selectivity and recovery rate. The microplasma-enabled synthesized method provides a promising path for preparing and applying carbon-based nanomaterials.