Design and development of a biosensor for uric acid detection based on self-assembled monolayers (SAMs) made on screen-printed gold electrodes.

This work presents the development of an enzymatic biosensor for uric acid (UA) detection based on the immobilization of uricase (Uox) on cysteamine (CYS) self-assembled monolayers (SAM). The SAMs were created on the surface of a screen-printed gold electrode (AuSPE) modified with gold nanoparticles (AuNPs) to allow the Uox immobilization using crosslinking. To verify the surface modifications, the electrodes were characterized by scanning electron microscopy (SEM), X-ray energy dispersive spectrometry (EDS) and cyclic voltammetry. The structural techniques corroborated the SAMS formation over the AuNPs electrode and the improved electrochemical performance after all the modifications. Finally, the assembled biosensor was evaluated against UA showing a wide sensing range from 1.68 to 336.20 mg/dL, a sensitivity of 0.6607 with an R2=0.9632. The device also showed good selectivity against interference species like ascorbic acid. The biosensor showed promising results as an alternative method for fast, sensitive, and straightforward uric acid detection.