Enhancing analytical performance of tyrosinase-based sensors with nanoparticles for detection of isoproterenol

In this work, electrochemical biosensors utilizing tyrosinase (Tyr) for the detection of the nonselective beta-adrenergic agonist isoproterenol (ISO) are presented. Three different configurations for immobilizing Tyr on a graphite electrode (GE) are compared: (1) GE modified with poly(diallyldimethylammonium chloride) (PDADMAC), PDADMAC/Tyr/GE; (2) PDADMAC combined with iridium nanoparticles (IrNPs) in a stepwise preparation, resulting in PDADMAC/IrNPs/Tyr/GE; and (3) a composite of PDADMAC and IrNPs mixed with Tyr at a 1:1 (v:v), forming PDADMAC/(IrNPs-Tyr)/GE. Surface morphology was characterized using scanning electron microscopy (SEM). Cyclic voltammetry (CV) and amperometry were applied to characterize the biosensor's performance. Within the linear range of 5 μM to 211 μM, the biosensor PDADMAC/Tyr/GE exhibited a limit of detection (LOD) of 1.4 μM and a limit of quantification (LOQ) of 4.1 μM. PDADMAC/IrNPs/Tyr/GE displayed improved sensitivity with an LOD of 0.9 μM and an LOQ of 2.8 μM. The configuration PDADMAC/(IrNPs-Tyr)/GE demonstrated the best performance with an LOD of 0.3 μM and an LOQ of 0.8 μM. The slopes (0.0147 μA/M, 0.0096 μA/M, and 0.0031 μA/M for PDADMAC/(IrNPs-Tyr)/GE, PDADMAC/IrNPs/Tyr/GE, and PDADMAC/Tyr/GE, respectively) of the concentration dependencies for the three sensor modifications (which represent the analytical sensitivity) demonstrate the achieved enhancement of analytical performance by IrNPs. Furthermore, the biosensor's ability to detect ISO in the presence of potential interferences, such as ascorbic acid, uric acid, and paracetamol, was assessed. Additionally, we demonstrated the biosensor's potential to detect ISO in diluted spiked human serum samples.