Electrocatalytic Hollow AgAu/SiO₂ Sensor for Multi-Matrix Isoproturon Monitoring

This study reports the development and application of an electrochemical sensor based on a glassy carbon electrode (GCE) modified with hollow AgAu nanoshells supported on SiO₂ (AgAu NSs/SiO₂) and Nafion as a binder. The proposed AgAu NSs/SiO₂/NF/GCE sensor demonstrated excellent analytical performance for detecting isoproturon (ISO), a persistent environmental contaminant of significant concern. The sensor exhibited a wide linear detection range from 0.75 to 20 μg L^-1, a low detection limit of 0.011 μg L^-1, and a quantification limit of 0.037 μg L^-1, meeting and exceeding regulatory requirements. Differential pulse voltammetry revealed a remarkable 220% increase in peak current response compared to the unmodified electrode, indicating superior electrocatalytic activity. The sensor also demonstrated high repeatability (RSD = 3.28%), reproducibility (RSD = 1.10%), and excellent selectivity with minimal interference from complex matrices. Its applicability was successfully validated in aquaculture water, tomato extract, and human plasma samples, achieving recovery rates ranging from 83.0 to 100.4%. The key contribution of this work is the synthesis of AgAu nanoshells via a galvanic replacement reaction and their integration into an electrochemical sensor, which exhibits enhanced sensitivity, selectivity, and environmental applicability. This novel sensing platform offers a practical, efficient, and versatile tool for ISO monitoring across diverse real-world samples.