An Electrochemical Biosensor with Dual Signal Outputs: Toward Simultaneous Quantification of pH and O₂ in the Brain upon Ischemia and in a Tumor during Cancer Starvation Therapy

Abstract

Herein, we develop a novel method for designing electrochemical biosensors with both current and potential signal outputs for the simultaneous determination of two species in a living system. Oxygen (O ) and pH, simple and very important species, are employed as model molecules. By designing and synthesizing a new molecule, Hemin-aminoferrocene (Hemin-Fc), we create a single electrochemical biosensor for simultaneous detection and ratiometric quantification of O and pH in the brain. The reduction peak current of the hemin group increases with the concentration of O from 1.3 to 200.6 μm. Meanwhile, the peak potential positively shifts with decreasing pH from 8.0 to 5.5, resulting in the simultaneous determination of O and pH. The Fc group can serve as an internal reference for ratiometric biosensing because its current and potential signals remain almost constant with variations of O and pH. The developed biosensor has high temporal and spatial resolutions, as well as remarkable selectivity and accuracy, and is successfully applied in the real-time quantification of O and pH in the brain upon ischemia, as well as in tumor during cancer therapy.

A SERS Optophysiological Probe for the Real‐Time Mapping and Simultaneous Determination of the Carbonate Concentration and pH Value in a Live Mouse Brain

“…More interestingly, no obvious differences in the CO 3 2− concentration and pH value were observed when the microprobes were inserted into different areas of the cortex (Figure S15). The decrease in pH was due to a lack of O 2 and ATP upon MCAO, resulting in the accumulation of lactic acid . Meanwhile, the equilibrium of Equation moved to the left, leading to a decrease in the CO 3 2− concentration.…”

The Rise of Fiber Electronics

“…[43] Of course,afiber device can emit light at 3608 8,w hich is important for applications in biomedical fields such as optogenetic stimulation of peripheral nerve bundles. [15] Upon implantation, the fiber sensor can accurately and stably detect chemical signals of the target tissue. [15] Upon implantation, the fiber sensor can accurately and stably detect chemical signals of the target tissue.…”

The Rise of Fiber Electronics

“…It can illuminate the entire nerve bundle in all angles, suggesting its potential as a powerful tool for biological research and diagnosis. The fiber device may also receive stimuli, particularly biological signals from the environment, at 360° with both high sensitivity and stability . Upon implantation, the fiber sensor can accurately and stably detect chemical signals of the target tissue.…”

“…On the one hand, compared with three‐dimensional bulk and two‐dimensional thin film devices, miniaturized fiber devices using soft fiber electrodes match well with biological tissues in terms of bending stiffness, and the fiber shape also favors deep penetration into various tissues with negligible tissue damage and avoids complex implantation procedures. These properties help form stable tissue‐electronics interfaces, which allow fiber devices to be implanted into the human body to detect signals from organs such as the brain and treat various diseases . On the other hand, fiber devices can be woven into electronic fabrics by mature textile technology.…”