Dual-mode ratiometric electrochemical and turn-on fluorescent probe for reliably detecting H2O2 in Parkinson's disease serum

Abstract

Accurate diagnosis and effective treatment of Parkinson's disease (PD) rely on the accurate detection of the corresponding biomarkers. The build-up of reactive oxygen species (ROS), for instance, hydrogen peroxide (H₂O₂), resulting in oxidative stress inside cells is closely related to the pathogenesis of PD. In this study, two compounds, Re-B and Re-OB, were synthesized through a simple one-step reaction. Upon reacting with H₂O₂, the borate ester group in Re-B is selectively cleaved, restoring the phenol group. This leads to both a dual-signal ratiometric electrochemical response and a ``turn-on'' fluorescence effect. The Re-B probe demonstrates a clear ``turn-on'' electrochemical current response at −311.1 mV, followed by a ``turn-off'' response at −257.6 mV when interacting with H<sub>2</sub>O<sub>2</sub> on a single-walled carbon nanotube-modified screen-printed carbon electrode (SPCE/SWCNTs). Concurrently, the fluorescence spectrum shows a ``turn-on'' response with an emission peak at 586 nm. The fluorescence and ratiometric electrochemical methods developed in this study show exceptionally high sensitivity and selectivity for H₂O₂, with detection limits as low as 0.5 μM for the electrochemical method and 0.1 μM for fluorescence. The consistency between the results from both electrochemical and fluorescence quantification of H₂O₂ levels in serum underscores its reliability. This approach has significant potential as a point-of-care diagnostic device for PD early detection, providing valuable information for timely diagnosis and treatment.