An electrochemical and fluorescence dual-signal assay based on Fe3O4@MnO2 and N-doped carbon dots for determination of hydrogen peroxide

A novel electrochemical and fluorescence dual-signal assay was developed for the determination of hydrogen peroxide (H 2 O 2 ) based on Fe 3 O 4 @MnO 2 and N-doped carbon dots (NCDs). Fe 3 O 4 @MnO 2 was not only applied as the recognizer for H 2 O 2 but also served as the fluorescence quencher and electrochemical enhancer. This permits the dual-signal readout of the analytical system. In the absence of H 2 O 2 , the NCDs were quenched by Fe 3 O 4 @MnO 2 , and the oxidation of the electrochemical probe ferrocene (Fc) was catalyzed by Fe 3 O 4 @MnO 2 . In the presence of H 2 O 2 , MnO 2 was reduced to Mn 2+ , leading to the fluorescence recovery of NCDs and the reduction in the oxidation signal of Fc. By combining the electrochemical method and the fluorescence assay, more comprehensive and valuable information for H 2 O 2 determination was provided to meet different analytical demands. The method exhibits good repeatability and selectivity with a detection limit of 1.0 μM for the fluorescence assay and 0.6 μM for the electrochemical method. The proposed approach holds great potential for probing released targets from living cells. Graphical abstract