The sensitivity of semiconductor gas detectors to biomarkers characterizing intestinal function contained in the patient’s exhalation was increased by employees of the Laboratory of Chemistry and Physics of Semiconductor and Sensory Materials of the Faculty of Chemistry of Moscow State University, the university’s press service reported on August 22.
Scientists have managed to increase the sensitivity of these sensors to short-chain fatty acids contained in the air exhaled by a person, which increases the prospects for an adequate and non-invasive diagnosis of the patient’s health status.
Biomarkers contained in exhaled air and associated with human health and performance indicators may include, for example, acetone, formaldehyde, ethanol and other volatile organic compounds in exhalation.
The director of the research, Marina Rumyantseva, professor of the Department of Inorganic Chemistry of the Faculty of Chemistry of Moscow State University, spoke about the topic of the research:
“In the last decade, much attention has been paid to studying the role of short-chain fatty acids in the onset of various diseases. These acids are known as the most important metabolic products of the intestinal microbiota. According to recent medical research, increasing their production in the intestines is a way to prevent gastrointestinal dysfunction, obesity and type 2 diabetes.”
This raises the task of monitoring the level of these biomarkers in exhaled air, which can serve as a non-invasive method of monitoring the effectiveness of prescribed treatment or patient compliance with a diet.
In this case, exhaled air analyzers can be inexpensive, miniature and highly sensitive semiconductor gas sensors based on metal oxides. Since the interaction of gas molecules with the surface of such a semiconductor causes a change in its conductivity, it can serve as a sensor signal.
Tin dioxide is the most studied and sensitive material for this type of sensor. But to analyse exhaled air, it was necessary to increase its sensitivity to the target biomarkers.
“To increase the sensitivity to acids, we decided to reduce the Lewis acidity of the materials.“said the first author of the study, graduate student of the Department of Inorganic Chemistry Alina Sagitova. We have synthesized a series of substances based on tin dioxide modified with lanthanum compounds. Lanthanum was chosen as a modifying additive, since lanthanum oxide is less acidic compared to tin dioxide.”.
The researchers studied the sensory properties of the improved material against a series of inorganic gases and short-chain fatty acids, showing reduced surface acidity of the modified materials compared to tin dioxide.
At the same time, an increase in sensitivity to gases with acidic properties (short-chain fatty acids and hydrogen sulfide) was found, but a decrease in the signal when detecting ammonia, which has pronounced basic properties.
“We have thus demonstrated the effectiveness of the proposed concept in specifically increasing the sensor signal when detecting gases with acidic properties, such as short-chain fatty acids.”, explained Marina Rumyantseva. The results of the work clearly show that the resulting materials are capable of detecting acids in concentrations below ppm in the air, even under very high humidity conditions. This makes sensors based on them promising for determining these biomarkers in exhaled air for medical analysis purposes.”.
The work done by the MSU scientists was described in detail in the paper, “Determination of Subppm Short-Chain Fatty Acids Using La(III)-Modified SnO₂ Gas Sensors,” published in the journal Sensors and Actuators B: Chemical.
Source: Rossa Primavera
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