21-0043 Method for Analyte Measurement with a Micro-Sized Electrode

  • Accurate and reproducible analyte measurements with a significantly smaller 10 micrometer electrode.
  • Smaller electrode allows for production of smaller biosensors (e.g. continuous glucose monitoring systems, painless sensors for in vivo monitoring, single cell monitoring).

Abstract

Background
Biosensors are analytical devices that incorporate material associated with or integrated within a physiochemical transducer to measure an enzymatic reaction. The most common electrochemical biosensors are those for measuring glucose. The major method of measurement of glucose biosensors is by amperometric measurement of oxidation reactions of substrates catalyzed by the enzyme, glucose oxidase. To detect the reactions, the electrical current is monitored by measuring the decreased oxygen concentration, or increased hydrogen peroxide, formed by the oxidase reaction. Alternatively, synthetic electron acceptors have been utilized instead of oxygen, and the change in reduced electron acceptors is electrochemically monitored. An advanced method of measurement is by utilizing direct electron transfer (DET) enzymes, which are capable of transferring electrons from the redox reaction directly to the electrode. Amperometric sensors are limited by the inability to reduce the size of the sensors. The inherent issue with downsizing the sensor size is that the electrical current measurements are proportional to the surface area of the sensors and with a sensor that is too small, the current would be indistinguishable from background noise. However, an open circuit potential (OCP) based enzyme sensor can measure reactions independent of sensor size but presents longer detection times (up to 1 minute). Additionally, OCP based glucose sensors present glucose concentration in a logarithmic scale, which is not as relevant for users, as it is ideal for the glucose concentration to be provided directly on a linear scale. These challenges show that the current electrochemical biosensors have inherent limitations associated with size, time of detection, and scale of the analyte concentration.

Technology Overview
Researchers in the Departments of Biomedical Engineering and Chemistry have developed a new innovative principle, which calculates the differentiation of OCP by time (dOCP/dt) or “transient potentiometry”, for electrochemical sensing of analytes such as, glucose, serine, and lactate. The transient potentiometry principle measures the time dependent change of the OCP between an immobilized redox enzyme electrode and a counter electrode in the presence of the target analyte. This principle allows for direct measurement of analyte concentration (linear not logarithmic) in less than one second. Proof-of-concept has been demonstrated using a 10 micrometer electrode to measure the concentration of glucose, lactate, and D-serine accurately, reproducibly, and within one second. This new sensing principle resolves previous issues associated with DET enzymes or OCP based sensing methods such as size limitations and time of detection. Importantly, by allowing a smaller electrode to be used for measurements, this principle opens the door for a new class of smaller and more accurate wearable biosensors systems.

Website

https://unc.flintbox.com/technologies/79C0BC01AF30456DBE69921B4F1F046C

Advantages

  • Analyte concentration measured within 1 second.
  • Accurate and reproducible analyte measurements with a significantly smaller 10 micrometer electrode.
  • Smaller electrode allows for production of smaller biosensors (e.g. continuous glucose monitoring systems, painless sensors for in vivo monitoring, single cell monitoring).
  • Compatible with many systems utilizing different redox enzymes such as, glucose dehydrogenase, glucose oxidase, lactate oxidase, lactate dehydrogenase, D-amino acid oxidase, fructosyl amino acid oxidases, glycerol-3phosphate oxidase, or fructose dehydrogenase.

Potential Applications

Fast and accurate measurement of analytes such as, glucose, serine, and lactate, in commercially available biosensors and novel small wearable biosensors that utilize smaller electrodes.

Contact Information

Name: Matthew Howe

Email: matthew.howe@unc.edu

Phone: 919.966.3929