In this work, a novel portable and wireless intelligent electrochemical nanosensor was developed for the detection of 6,7-dihydroxycoumarin (6,7-DHC) using a modified screen-printed electrode (SPE). Black phosphorene (BP) nanosheets were prepared via exfoliation of black phosphorus nanoplates. The BP nanosheets were then mixed with nano-diamond (ND) to prepare ND@BP nanocomposites using the self-assembly method, achieving high environmental stability. The nanocomposite was characterized by SEM, TEM, Raman, XPS and XRD. The nanocomposite was used for the modification of SPE to improve its electrochemical performances. The nanosensor displayed a wide linear range of 0.01–450.0 μmol/L with a low detection limit of 0.003 μmol/L for 6,7-DHC analysis. The portable and wireless intelligent electrochemical nanosensor was applied to detect 6,7-DHC in real drug samples by the standard addition method with satisfactory recoveries, which extends the application of BP-based nanocomposite for electroanalysis.

In this paper, a highly conductive alkali-activated graphitized carbon (a-GC) was prepared using tilapia fish scales as precursors through enzymolysis, activation and pyrolytic carbonization methods. The prepared a-GC was modified on the surface of a screen-printed carbon electrode to construct a flexible portable electrochemical sensing platform, which was applied to the differential pulse voltametric detection of dopamine (DA) using a U-disk electrochemical workstation combined with a smart phone and Bluetooth. The prepared a-GC possesses good electrical conductivity, a large specific surface area and abundant active sites, which are beneficial for the electrooxidation of DA molecules and result in excellent sensitivity and high selectivity for DA analysis. Under the optimal conditions, the oxidation peak current of DA increased gradually, with its concentrations in the range from 1.0 μmol/L to 1000.0 μmol/L, with the detection limit as low as 0.25 μmol/L (3S/N). The proposed sensor was further applied to the determination of DA in human sweat samples, with satisfactory results, which provided an opportunity for developing noninvasive early diagnosis and nursing equipment.