Square nanoplate–like tungsten oxide nanostructure–based sensor for electrochemical dopamine detection in human serum and saliva

Developing compact, high-performance sensors for detecting biofluid disease biomarkers can significantly enhance and revolutionize health monitoring systems. In this report, we present the synthesis of square nanoplate-like tungsten oxide (SNP-WO₃) nanostructures using an acid-assisted, low-temperature hydrothermal process and characterise them using various techniques. Using the SNP-WO₃ nanostructure, we have fabricated an electrochemical-based dopamine (DA) sensor. The conductive grade poly(2,3-dihydrothieno-1,4-dioxin)-poly(styrenesulfonate) (PEDOT:PSS) was employed alongside the SNP-WO₃ nanostructure to enhance stability and synergize DA detection. The SNP-WO₃ nanostructure and PEDOT:PSS slurry were deposited onto a screen-printed carbon electrode (SPCE), and the sensor fabrication steps were examined using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The optimised WO₃-PEDOT:PSS modified SPCE sensors implemented DA detection techniques, including CV, chronoamperometry, and DPV. The sensor exhibited a linear detection range of up to 4000 μM DA during CV and chronoamperometry measurements, whereas DPV demonstrated a linear range of up to 1000 μM. Notably, DPV outperformed CV and chronoamperometry in terms of sensitivity (2.1485 μA/μM/cm²) and detection limit (0.019 μM), establishing it as the most effective technique for DA quantification. Furthermore, the sensor displayed exceptional selectivity for DA and excellent fabrication reproducibility, cyclic stability, and long-term stability of up to 8 weeks, ensuring reliable performance over time. The sensor's applicability was validated by detecting DA in human blood serum and artificial saliva samples, achieving high accuracy. These findings highlight the WO₃-PEDOT:PSS nanostructure as an emerging platform for electrochemical sensing with significant potential in neurochemical analysis and clinical diagnostics.