Phenylketonuria monitoring in human blood serum by mosses extract/ZnO@Au nanoarrays-loaded filter paper as a novel electrochemical biosensor

Abstract

In this paper, ZnO nanorods with the coverage of gold nanoparticles alongside enzyme phenylalanine hydroxylase available in the extract of mosses leaf-like tissue were applied to the fabrication of a novel phenylalanine electrochemical biosensor. The synthesized ZnO@Au hybrid nanoarrays were characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transfer infrared (FT-IR) techniques. The enzyme immobilization was done by dropping the ZnO@Au hybrid nanoarrays and the mosses extract respectively onto a filter paper disc. The modified paper was placed on the top of the graphite screen printed electrode (GSPE). The electrochemical characteristics of the biosensor were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods for different fabrication steps. The changes in the electrochemical response of biosensor versus the concentration of phenylalanine were monitored by differential pulse voltammetry (DPV). Under the optimal conditions, the linear relationship between the DPV signals and phenylalanine concentrations were obtained in the range of 5.0 nM to 100 µM with a detection limit (S/N = 3) and limit of quantitation of 3.0 nM and 10.0 nM, respectively. This method was successfully applied for the determination of phenylalanine in the human blood serum samples.