Self-Assembled Monolayers on Screen-Printed Gold Electrodes for Uricase Enzyme Covalent Immobilization

Abstract

This work reports the development of an electrochemical biosensor for uric acid (UA), based on covalent immobilization of uricase (Uox) on cysteamine self-assembled monolayers (SAM). The monolayers were prepared over screen-printed gold electrode (AuSPE) modified with Au nanostructures for covalent linkage through EDC-NHS. The modified AuSPE was characterized by Scanning Electron Microscope (SEM) and Cyclic Voltammetry (CV). The results verified the cysteamine SAM formation, and the improved electrochemical performance of the working surface. The AuSPE/SAM/Uox biosensor presented a linear range of 0.84 – 16.81 mg/dL (50-1000 µM), a sensibility of 9.1423 µA/(mg/dL)cm2, and a limit of detection (LOD) of 0.0700 mg/dL. The biosensor did not present a response due to ascorbic acid (AA), verifying the selectivity of the assembly only to UA oxidation. The AuSPE/SAM/Uox showed a promising performance as a reliable, simple and fast detection tool for UA.