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

Abstract

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.