Screen-printed carbon electrode functionalized with AuNPs-cysteamine self-assembled monolayers for enzymatic uric acid detection in non-invasive samples.

Uric acid (UA) is a relevant biomarker that at abnormal levels could provide information for the timely diagnosis of chronic-degenerative diseases, such as Diabetes mellitus, cardiovascular deficiencies or gut. This work presents a simple surface functionalization of screen-printed carbon electrodes (SPCE) with cysteamine self-assembled monolayers (SAMs) assembled over electrodeposited gold nanoparticles (AuNPs). The modification allowed the immobilization of uricase enzyme, preserving its biocatalytic activity and resulting in sensitive and selective UA detection. The developed biosensor device exhibited a linear detection range from 100 μM – 1000 μM, a sensitivity of 6.622 nA/μM and a limit of detection (LOD) of 4.6 μM with selectivity to UA molecules over common interfering analytes. When evaluated in urine samples, the analytical capabilities of the PTSPCE/AuNPS/SAMs/Uox biosensor remained, achieving an average recovery rate of 126.91%. The obtained analytical parameters proved to be competitive when utilizing non-invasive fluids, suggesting the possibility of conducting detection assays with potential clinical applications using an implemented electrochemical biosensor through a simple, flexible, and reproducible methodology.