A matrix of perovskite micro-seeds and polypyrrole nanotubes tethered laccase/graphite biosensor for sensitive quantification of 2,4-dichlorophenol in wastewater

The present study demonstrates the fabrication of a laccase (lac) biosensor to detect and quantify 2,4-dichlorophenol (2,4-DCP) using a lac immobilized polypyrrole nanotube (PPyNT) and strontium copper oxide (SrCuO2) micro-seed composite modified graphite electrode. The SrCuO2 was synthesized using the co-precipitation method and PPyNT was grown using a methyl orange template. Scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction spectroscopy (XRD) techniques were used in the characterization of SrCuO2 and PPyNT. Furthermore, PPyNT and SrCuO2 were deposited onto the graphite electrode (Gr) and used as a platform for immobilization of the lac enzyme. SEM micrographs of the Gr/PPyNT/SrCuO2/lac electrode authenticated the deposition of nanomaterials and the enzyme, whereas the electrochemical impedance spectroscopy (EIS) results demonstrated the conducting nature of SrCuO2 and the successful enzyme immobilization. Compared to the unmodified electrode, Gr/PPyNT/SrCuO2/lac displayed a higher electrocatalytic behavior towards 2,4-DCP. The performance of the sensor was calibrated and evaluated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The sensor exhibited a wide linear range (1–50 μM), a low detection limit (LOD) (0.18 μM) and high sensitivity (4.715 μA μM−1 cm−2). In addition, the proposed sensor exhibited good repeatability, reproducibility and stability. The real sample analysis results indicated an acceptable recovery up to 94%, which suggested that the sensor could be used to monitor 2,4-DCP.