In this work, a novel and sensitive electrochemical biosensor was constructed based on a black phosphorene (BP) and nanosized zinc oxide (ZnO@BP) nanocomposite as a modifier, which was used for the immobilization of horseradish peroxidase (HRP) on a carbon ionic liquid electrode (CILE). The ZnO@BP nanocomposite was synthesized by a simple in situ hydrothermal method with stripped black phosphorus nanoplates and ZnO. The ZnO@BP and HRP-modified electrode was developed by a casting method. ZnO@BP with highly conductivity, large surface area and good biocompatibility could maintain the bioactivity of HRP and accelerate the electron transfer rate. Cyclic voltammetry was used to study the direct electrochemistry of HRP on the Nafion/HRP/ZnO@BP/CILE with the appearance of a pair of distinct redox peaks. The constructed electrochemical HRP biosensor exhibited excellent electrocatalytic effects on the reduction of trichloroacetic acid and sodium nitrite. Real samples were detected with satisfactory results, which demonstrated the potential applications of this electrochemical HRP biosensor.

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.