Researchers at the University of Bath working in collaboration with industrial partner, Integrated Graphene, have developed a new sensing technique based on graphene foam for the detection of glucose levels in the blood. Since it is a chemical sensor instead of being enzyme-based, the new technology is robust, has a long shelf-life and can be tuned to detect lower glucose concentrations than current systems.
Diabetes affects around 4.9 million people in the UK and is a chronic condition where the patient cannot naturally regulate their blood sugar levels. Therefore, the patient must measure their blood sugar levels several times a day as part of managing their condition.
Many current biosensors use enzymes that bind glucose and produce an electric current proportional to the concentration of glucose in the blood sample.
The new technique is more robust and is not affected by high temperatures or changes in pH. Furthermore, it has the potential to accurately detect a wider range of glucose concentrations above and below current biosensor ranges, which may be useful in neonatal glucose sensing.
The sensor is based on the chemical, boronic acid, which is attached to a graphene foam surface. An electroactive polymer layer is added on top and binds to the boronic acid. When glucose is present, it competitively binds to the boronic acid, displacing the polymer. The sensor produces an electric current proportional to how much polymer is displaced, meaning that the concentration of glucose in the sample can be accurately measured.
The researchers anticipate the sensor will expand the scope of boronic acid-based glucose sensing. Since their sensor is based upon electrochemical methods rather than fluorescence, it will enable new boronic acid-based glucose sensing approaches.
“We hope that in the future we might be able to apply our glucose detection method to exciting new technologies, such as wearable or implantable glucose monitoring systems. The graphene foam electrode has a high surface area to interact with the blood sample, while the polymer can act as a molecular sieve, filtering out larger molecules in the blood that could interfere with the glucose sensing. This sensor has proven to be reusable, which is the first step towards realizing a continuous monitoring system. This same sensing technique may also be applied to a wide range of other targets, such as lactic acid. This is due to the versatile nature of the boronic acid receptor, which gives us a general strategy for a variety of sensing applications,” said Simon Wikeley, PhD candidate at the University of Bath.
Professor Tony James said: “We’re excited by our results, as this is the first time this approach has been used for glucose sensing. We are still in the early stages of optimizing sensitivity and reproducibility but hope this new technology could be used in a wide range of applications, from medical sensing to food production. It could also be adapted to sense other molecules or for use in continuous flow systems.”