MSU: Electrocatalyst to ensure the operation of glucose biosensors

Main article: Blood glucose monitoring systems

2025: Building an Ultrastable Electrocatalyst

Scientists have created an ultra-stable electrocatalyst that allows biosensors that measure glucose levels to run continuously for several days without losing sensitivity. This is fundamentally important for monitoring the condition of patients with diabetes mellitus with minimally invasive and non-invasive wearable devices, excluding the need for their calibration related to blood sampling. This was announced by the Russian Scientific Foundation (RSF) on July 11, 2025.

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Фото: Arkady Karjakin

Diabetes mellitus affects 590 million people worldwide, according to the International Diabetes Federation. This disease, which comes to the 7th place in mortality, is dangerous for its complications, such as atherosclerosis, blindness, kidney failure and others. Diabetes mellitus is still practically not curable, but it is possible to delay complications by maintaining the concentration of glucose in the blood in the required range.

People with the disease need to monitor glucose concentration several times a day. To avoid injury and infection associated with blood sampling, minimally invasive and non-invasive wearable devices are gaining increasing attention. The devices on the market are based on biosensors implanted into the body to a depth of 5 millimeters for continuous glucose monitoring, claimed to be in tissue fluid. The problem of most such devices remains the need to calibrate them daily by taking blood.

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Фото: Arkady Karjakin

The principle of operation of most glucose biosensors, including those used in clinical analyzers, is to detect hydrogen peroxide (N2O2), the product of the glucose oxidation reaction catalyzed by the enzyme glucose oxidase. However, the oxidation of hydrogen peroxide on platinum, proposed back in the 1970s and used so far, is complicated by a false positive signal to reducing agents, for example vitamin C, urea, which can give a response comparable to a reaction to glucose. A double overestimation of its concentration is dangerous in that the difference between the "norm" and the contents at which a diabetic coma was observed is less than one and a half times.

Back in 1994, scientists from Moscow State University named after M.V. Lomonosov presented an electrocatalyst that allows detecting hydrogen peroxide by its reduction, thus solving the problem of a false positive signal. In addition to high selectivity, specially synthesized Berlin azure (iron hexacyanoferrate) is characterized by 1000 times higher sensitivity compared to platinum, allowing analyzing not only blood, where the glucose concentration is quite high, but also excretory fluids, for example, sweat, laying the foundations for non-invasive analysis - without piercing blood vessels and damage to the skin.

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Фото: Arkady Karjakin

In this work, scientists have obtained a composite material by the joint synthesis of iron and nickel hexacyanoferrates. The task was to stabilize the electrocatalyst with nickel hexacyanoferrate at a micro level. The synthesis was carried out at the electrode-solution phase interface - the area where the electrochemical interaction between the solid electrode and the liquid medium takes place. According to to data electron microscopy, the crystals of the composite filling the entire surface of the electrode are 5-6 times larger than the crystals of Berlin azure. Little inferior to pure Berlin azure in catalytic activity, the composite is ten times superior in operational stability. The glucose biosensor created by applying glucose oxidase over the composite electrocatalyst did not lose sensitivity for more than three days of continuous monitoring of physiological glucose concentration.

The use of the developed ultra-stable electrocatalyst will make it possible to create non-calibrated both minimally invasive and non-invasive monitors of diabetes mellitus, "said Arkady Karjakin, Doctor of Chemistry, Professor of the Faculty of Chemistry, Moscow State University named after M.V. Lomonosov.