Russian scientists have developed a biosensor based on the Prussian blue pigment, which determines the levels of glucose and lactate in blood and sweat with an accuracy of 99%. Certain concentrations of these molecules can indicate overwork, as well as diseases such as diabetes and meningitis. The proposed device is compact and easily attached to the surface of the skin, so it can be used for continuous monitoring of the health status of athletes and patients with diabetes. The results of the study, supported by a grant from the Russian Science Foundation (RSF), are published in the journal Sensors and Actuators, B: Chemical.
Professional athletes who experience significant physical exertion are often under the close attention of doctors who monitor their health. The state of the body can be assessed by various indicators, one of which is organic molecules involved in metabolism, that is, metabolism. Glucose and lactate are considered good “markers” because the levels of these substances deviate significantly from the norm if a person is overexerted or sick. For example, high levels of glucose and lactate in the absence of any exercise can indicate diabetes, meningitis, hypoxia (lack of oxygen) and sepsis, that is, blood poisoning. If, at rest, the indicators do not deviate from the norm, but as the training progresses, for example, among athletes, they increase, this should be a signal that
To monitor the levels of glucose and lactate in the body in real time, there are special sensors. At the same time, they measure the concentration of the corresponding compounds not directly, but fix the number of peroxide molecules formed during their oxidation in the blood. Therefore, the sensors must be attached to the blood vessels below the surface of the skin. Scientists are trying to make wearing such devices painless, avoiding damage to the skin and vessel walls.
Scientists from Lomonosov Moscow State University (Moscow) have developed a biosensor for monitoring glucose and lactate levels in human sweat, making it non-invasive and easy to use. The authors took electrodes coated with nanoparticles of Prussian blue, a pigment that is part of blue art paint, as the basis for the device. The peculiarity of this compound is that it is sensitive to hydrogen peroxide, due to which it can be used to convert a chemical signal about the concentration of peroxide into an electrical signal supplied to the electrode.
However, Prussian blue dissolves under the action of hydroxyl ions, which are present in the human body and sweat and are formed during the reduction of hydrogen peroxide. To avoid pigment dissolution, the researchers coated the nanoparticles with a protective layer of nickel hexacyanoferrate, which is more stable to hydroxyl ions.
Scientists experimentally tested the sensitivity of biosensors by placing them in solutions of glucose and lactate of different concentrations. It turned out that at any concentration of these molecules, characteristic of the human body, the device worked stably. Experiments with human blood and sweat samples have shown that the sensor detects glucose and lactate concentrations in both fluids with an accuracy of 99%. The device transmitted readings to a specially developed application on a smartphone using Bluetooth. The sample used in the laboratory displayed the measurement result as an electric current value, however, for the convenience of users, the scientists plan to program it automatically to convert to lactate and glucose values. Thanks to this, a person can easily and quickly obtain data and interpret them even without the participation of a doctor.
In addition, the authors compared the stability of a device based solely on Prussian blue with one whose particles were coated with a protective layer of nickel hexacyanoferrate. The samples had the same sensitivity, but the latter worked up to eight times longer. At the same time, the most stable sensors were based on particles with a size of 50 nanometers, comparable in size to small viruses.
“The proposed biosensors are stable and easy to use, thanks to which they can be used to monitor lactate and glucose levels in blood and sweat in athletes and patients with diabetes in real time,” says a participant in a project supported by a RSF grant and the first author of the work. Elena Daboss, Senior Researcher, Department of Analytical Chemistry, Faculty of Chemistry, Moscow State University.