Non-Fullerene Organic Semiconductor ITIC as a Redox Mediator in Electrochemical Glucose Biosensors

ITIC's superior electron-accepting capacity and efficient oxygen reduction motivated the design of a sensor to enhance sensitivity, selectivity, and stability over conventional oxygen-dependent or fullerene-based systems. As oxygen acts as the terminal reagent in enzymatic glucose oxidation, we developed an ITIC-mediated glucose oxidase (GOx) biosensor on glassy carbon (GCE) and screen-printed carbon electrodes (SPCE). ITIC, a non-fullerene organic semiconductor, was drop-cast onto the electrode to catalyze oxygen reduction, followed by GOx immobilization in a chitosan matrix. Scanning electron microscopy (SEM) confirmed uniform, ultrathin coatings without significant morphological changes upon ITIC and GOx deposition. Electrochemical studies (cyclic (CV) and differential pulse voltammetry (DPV)) revealed a distinct ITIC reduction peak at -0.7 V (vs. Ag/AgCl) and a glucose-dependent current decrease, consistent with mediated electron transfer during enzymatic oxidation. Under optimized conditions, the GCE-based biosensor showed a sensitivity of 10.7 μA L mmol^-1, a linear dynamic range (LDR) of 0.10-1.00 mmol L^-1, and detection (LOD)/quantification (LOQ) limits of 0.02 and 0.06 mmol L^-1, respectively. The SPCE device displayed sensitivity (3.8 μA L mmol^-1) and maintained excellent linearity (R² > 0.99) with LOD and LOQ of 0.05 and 0.16 mmol L^-1. Both platforms showed good precision (RSD < 5%) and reliable recovery in deproteinized plasma and artificial tears (90-104%). The superior performance of the GCE is attributed to higher ITIC loading, faster electron transfer, and reduced background current, while the SPCE offers a low-cost, disposable format with sufficient analytical performance for point-of-care glucose monitoring.