Multivariate analysis and electrochemical detection of uric acid using a novel Fe–Ni-MOF/RGO nanosheet-based uricase biosensor on glassy carbon electrode

We report the development of a highly innovative and selective biosensor for uric acid (UA) detection in plasma and urine samples, integrating bimetallic Fe–Ni-MOF nanoparticles with reduced graphene oxide (RGO) nanosheets and immobilized uricase (UOx) on a glassy carbon electrode (GCE). Unlike previously reported MOF- or RGO-based sensors, our design exploits the synergistic electro catalytic activity of Fe–Ni bimetallic centers and the high conductivity of RGO, coupled with an optimized enzyme loading, to achieve superior analytical performance. Critical experimental parameters—including Fe–Ni-MOF and RGO concentrations, enzyme volume, and pulse potential—were systematically optimized using central composite design (CCD) and response surface methodology, ensuring a statistically validated model confirmed by ANOVA. Under optimal conditions (Fe–Ni-MOF: 5.00 mg/mL; RGO: 1.91 mg/mL; UOx: 3.00 U/mL; pulse potential: 0.007 V), the biosensor exhibited a sharp anodic response at 0.31 V in phosphate buffer (pH 7.4). A broad linear range (0.005–5000 μM) with an ultralow detection limit of 0.21 µM was achieved, outperforming most state-of-the-art UA sensors. The sensor demonstrated excellent recoveries (99.1–101.7%) in real human plasma and urine samples, highlighting its accuracy, reproducibility, and strong potential for clinical diagnostics.