Low-cost and disposable sensors for the simultaneous determination of coenzyme Q10 and α-lipoic acid using manganese (IV) oxide-modified screen-printed graphene electrodes

Highlights: • The simultaneous determination of CoQ10 and ALA was firstly proposed. • The simple and inexpensive method for the fabrication of MnO₂/SPGE was presented. • The incorporation of MnO₂ into SPGE showed the greatly improved performance towards the oxidation of CoQ10 and ALA. • The proposed method can be applied in real samples with high accuracy. - Abstract: In this work, for the first time, manganese (IV) oxide-modified screen-printed graphene electrodes (MnO₂/SPGEs) were developed for the simultaneous electrochemical detection of coenzyme Q10 (CoQ10) and α-lipoic acid (ALA). This sensor exhibits attractive benefits such as simplicity, low production costs, and disposability. Cyclic voltammetry (CV) was used to characterize the electrochemical behavior of the analyte and investigate the capacitance and electroactive surface area of the unmodified and modified electrode surfaces. The electrochemical behavior of CoQ10 and ALA on MnO₂/SPGEs was also discussed. Additionally, square wave anodic stripping voltammetry (SWASV) was used for the quantitative determination of CoQ10 and ALA. Under optimal conditions, the obtained signals are linear in the concentration range from 2.0 to 75.0 μg mL⁻¹ for CoQ10 and 0.3–25.0 μg mL⁻¹ for ALA. The low limits of detection (LODs) were found to be 0.56 μg mL⁻¹ and 0.088 μg mL⁻¹ for CoQ10 and ALA, respectively. Moreover, we demonstrated the utility and applicability of the MnO₂/SPGE sensor through simultaneous measurements of CoQ10 and ALA in dietary supplements. The sensor provides high accuracy measurements, exhibiting its high potential for practical applications.