Researchers at Lomonosov Moscow State University, together with colleagues, have developed a new biosensor based on glucose oxidase and Prussian blue, capable of accurately measuring sugar levels in the interstitial fluid and blood of patients with diabetes.
The main problem with traditional sensors is the oxygen deficiency in the subcutaneous fluid, which is necessary for the reaction of the glucose oxidase enzyme with glucose. Scientists solved it by reducing the amount of enzyme on the sensor surface by 10–20 times.
In this mode, there is enough dissolved oxygen for operation, and the sensor maintains measurement accuracy even at high glucose concentrations — up to 5.4 grams per liter, which fully covers the range of sugar levels in humans.
To compensate for the decrease in sensitivity when reducing the enzyme, the device operates in a pulsed mode: hydrogen peroxide, the reaction product, accumulates on the electrode for 15 seconds, and then an amplified signal is recorded in fractions of a second. This approach increases the sensor's sensitivity by 100 times.
Experiments on rats have shown that the new sensor tracks sugar levels in the interstitial fluid in real time. The data obtained completely coincided with blood measurements, taking into account a delay of about 20 minutes, which is typical for subcutaneous detectors.