Development of a polyvinyl alcohol-capped copper nanocluster-integrated electrochemical sensor for trace-level monitoring of anthraquinone

In the current study, polyvinyl alcohol-capped copper nanoclusters (PVA-CuNCs) were synthesized <i>via</i> a chemical reduction method using PVA as a capping and stabilizing agent. The synthesized PVA-CuNCs were used for the fabrication of an ultra-sensitive electrochemical sensor to detect anthraquinone (AQ) at trace levels in an aqueous environment. The fabricated nanoclusters were thoroughly characterized using a wide range of analytical tools. FTIR analysis confirmed the functional properties of the PVA-CuNCs, while XRD investigation revealed a crystalline nature with an average size of 4.21 nm. Their elemental composition was assessed through EDX, indicating a clean copper-based matrix without any notable impurity. Furthermore, the DLS showed an average hydrodynamic diameter of 2.71 nm, and AFM imaging provided a 2D/3D surface profile with a particle size of approximately 6.5 nm. The synthesized nanocluster was then immobilized on a platinum electrode to fabricate a PVA-CuNCs/PtE sensor, which was employed for the electrochemical detection of AQ. Under optimized conditions, such as phosphate-buffered saline at pH 6, a scan rate of 220 mV s^-1, and a potential window of -0.4 to +0.8 V, the sensor demonstrated a sensitive and linear response to AQ, with an LOD of 0.056 μM and an LOQ of 0.17 μM. The fabricated sensor also performed exceptionally well in real water samples, including river water and industrial wastewater, showing recovery values within acceptable limits. The results confirm the potential of PVA-CuNCs as an efficient and reliable sensing platform for AQ detection in environmental monitoring.