A Novel Electrochemical Biosensor with Dual Signal Outputs: Toward Simultaneous Quantification of pH and O2 in Brain upon Ischemia and in Tumor during Cancer Therapy

In this work, we develop a novel methodology for designing electrochemical biosensors with both current and potential signal outputs for simultaneous determination of two important species in the live systems. By designing a new molecule, Hemin-aminoferrocene (Hemin-Fc), we create a single electrochemical biosensor for simultaneous quantification of O2 and pH in brain upon ischemia and in tumor during cancer starvation therapy. The reduction peak current of Hemin group increases with rising concentrations of O2 from 1.3 to 200.6 μM. Meanwhile, this peak potential positively shifts with decreasing pH from 8.0 to 5.5, resulting in simultaneous determination of O2 and pH by monitoring both current and potential signal outputs. The developed single biosensor with high temporal and spatial resolutions, as well as remarkable selectivity and accuracy, is successfully applied in determination of O2 and pH in brain upon ischemia, as well as in tumor during cancer therapy.