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

Abstract

Miniaturized and integrated devices for fast determination of clinical biomarkers are in high demand in the current healthcare environment. In this work, we present a functionalized self-assembled monolayer (SAM) on the gold surface of a screen-printed electrode (Au-SPE). The device was applied for uric acid (UA) detection, a biomarker associated with arthritis, diabetes mellitus, and kidney function. Prior to SAM formation, AuSPE was subjected to pretreatment with KOH and Au electrodeposition to provide additional roughness to the substrate. The SAM was formed in the AuSPE/KOH/AuNP surface by the cysteamine method—carried out for working surface dipping in the cysteamine (CYS) solution at 20 mM for 24 h (rinsed with ethanol and milli-Q water). Then, the uricase enzyme was immobilized through physical absorption at room temperature for 1 h to obtain the AuSPE/KOH/AuNPs/SAM/Uox biosensor. The physical and electrochemical characterization of AuSPE modification was carried out by scanning electron microscopy (SEM) and cyclic voltammetry (CV). The calibrated data of the Au/KOH/AuNPs/SAM/Uox biosensor showed a linear relation in the range of 50–1000 µM, a sensibility of 0.1449 µA/[(µM)cm2], and a limit of detection (LOD) of 4.4669 µM. The Au/KOH/AuNPs/SAM/Uox also exhibited good selectivity for UA in the presence of ascorbic acid. Moreover, the methodology showed good reproducibility, stability, and sensitive detection of UA. This performance of the proposed biosensor is in good accordance with clinical needs and can be compared with previous biosensors based on nanostructured surfaces of high-fabrication complexity.

Keywords

• AuNPs
• AuSPE
• biosensor
• CV
• electrochemist
• uric acid