A highly sensitive uric acid electrochemical biosensor based on a nano-cube cuprous oxide/ferrocene/uricase modified glassy carbon electrode

Qinghua Yan,Qigao Feng,Shujuan Sun,Qiqing Zhang,Na Zhi,Li Yang,Guangri Xu

doi:10.1038/s41598-020-67394-8

Abstract

A uric acid (UA) electrochemical biosensor was constructed using ferrocene (Fc) decorated cuprous oxide (Cu2O) enhanced electro-active characteristics and covalently immobilized with uricase (UOx) on glassy carbon electrode (GCE). The electrochemical characteristics of the fabricated electrode was analysed by cyclic voltammetry, electrochemical impedance spectroscopy and differential pulse voltammetry (DPV). DPV studies revealed rapid response of fabricated electrode UOx/Fc/Cu2O/GCE towards UA in a wide concentration range of 0.1–1,000 μM with a sensitivity of 1.900 μA mM−1 cm−2 and very low detection limit of 0.0596 μM. A very low magnitude Michaelis–Menten constant (Km) value was evaluated as 34.7351 μM which indicated the chemical attraction of the enzyme towards the UA was much higher. The developed biosensor was successfully applied to detect UA in human urine samples. Moreover, reproducibility and stability studies demonstrated the fabricated UOx/Fc/Cu2O/GCE biosensor had high reproducibility with a RSD of 2.8% and good reusability with a RSD of 3.2%. Specificity studies results showed the fabricated biosensor had strong anti-interference ability. The improved sensor performance was attributed to the synergistic electronic properties of Cu2O and Fc that provided enhances delectrocatalytic activity and electron transfer. The present biosensor can be extended for use in clinical settings.

Highlights

In the current worldwide field of disease diagnosis and treatment, there is an urgent requirement to develop a device that can recognize, detect and quantify metabolites in important biochemical processes of human body for rapid, simple and accurate diagnosis of various diseases
X-Ray diffractometer (XRD) spectra of Cu2O NPs showed the diffraction peaks appeared at a 2θ value of 29.48°, 36.38°, 42.20°, 61.32°, 75.26° and 76.30° corresponds to the (110), (111), (200), (220), (311) and (222) characteristic planes, and confirmed that all the diffraction peaks in the XRD spectrum correspond to the standard pattern of cuprous oxide cubic crystal system (PDF#05-0667, cell parameter a = 0.4269 nm) (Fig. S1), and had high diffraction intensity and sharp peak shape, indicating that the products had good crystallinity[25,26]
It can be seen from the XRD spectra that the synthesized nanoparticles had no impurity peak, indicating that the product had a single crystal shape and high crystal purity (Fig. 2A)

Summary

Introduction

In the current worldwide field of disease diagnosis and treatment, there is an urgent requirement to develop a device that can recognize, detect and quantify metabolites in important biochemical processes of human body for rapid, simple and accurate diagnosis of various diseases. Because conjugation of Fc and UOx can provide novel systems promoting electron transfer.[18] In the energy spectrum sodium and phosphorus elements appeared indicating UOx in PBS buffer solution was modified on the Fc/Cu2O/GCE electrode (Fig. 3I).

Results

Conclusion