Dec 17 2019
Researchers from KAUST have created an electronic biosensor that is powered by the glucose present in bodily fluids. The device couples an electron-transporting polymer with an enzyme that derives electrons from its reaction with glucose to power its circuitry.
A schematic of the all-polymer bio-fuel cell, which draws energy from the glucose naturally present in saliva. Image Credit: © 2019 KAUST; Heno Hwang.
Therefore, the plastic bio-sensor may possibly serve as a constant monitor of essential health indicators such as blood sugar levels in diabetes patients.
Quick, accurate and early detection of abnormalities in metabolism is of paramount importance to monitor, control and prevent many diseases, including diabetes. Today’s glucose monitors are mainly limited to finger-pricking devices, which are often painful.
David Ohayon, PhD student, KAUST
Ohayon led the research in collaboration with postdoctoral colleague Georgios Nikiforidis. Although implantable glucose-sensing devices are being created, their batteries make implantation more difficult, and hence must be replaced or recharged finally.
Implantable polymer biosensors would be an optimal alternative technology since they exhibit the potential to drive themselves by making use of molecules around them.
Inal and her colleagues have come across a polymer, developed by Iain McCulloch’s group at KAUST, which seems to be well-suited for the task.
The polymer is an n-type semiconductor, meaning that it can accept and transport electrons along its backbone.
David Ohayon, PhD student, KAUST
The polymer is combined with the glucose oxidase enzyme that oxidatively derives electrons from its reaction with glucose. In general, there is a need for a third component to shuttle the electrons from the enzyme to the polymer.
“These mediators are often toxic and need to be immobilized onto the electrode surface, which complicates device miniaturization and shortens lifetime,” stated Ohayon.
The novel polymer does not require such a mediator. “Our polymer seems to be able to host the enzyme in such proximity that it enables efficient electrical communication between the active center and the polymer backbone.”
The ethylene glycol side chains of the polymer are perhaps the factor crucial to the interaction, a theory that is being investigated at present, in collaboration with Enzo di Fabrizo’s team at KAUST.
The research team made use of this n-type polymer material in a transistor to detect the levels of glucose in saliva. Moreover, it was also used as one half of an all-polymer fuel cell that makes use of glucose as an energy source to power the device.
This fuel cell is the first demonstration of a completely plastic, enzyme-based electrocatalytic energy generation device operating in physiologically relevant media.
Sahika Inal, Assistant Professor, KAUST
Inal added, “Glucose sensing and power generation are only two examples of the applications possible when a synthetic polymer communicates effectively with a catalytic enzyme-like glucose oxidase. Our main aim was to show the versatile chemistry and novel applications of this special water-stable, polymer class, which exhibits mixed conduction (ionic and electronic).”