A new generation of test strips
Rapid tests on quantum dots will be able to carry out an early diagnosis of a heart attack and detect sepsis within 10 minutes
NUST MISIS scientists have developed a new type of membrane test strips for quantitative immunochromatographic rapid analysis (rapid test), which will be able to accurately and quickly make an early diagnosis of acute myocardial infarction based on the presence of disease markers in the blood, as well as detect sepsis, determine the duration of pregnancy and distinguish between viral and bacterial infections.
Today, one of the urgent tasks in the field of analytical biotechnology is the development of new methods and devices that allow rapid analysis of mixtures of biologically active compounds. These methods are subject to such requirements as ease of analysis, high sensitivity and low cost. Tests based on the principle of immunochromatography (the most famous of them is the pregnancy test) are extremely easy to use. They are based on the recognition of individual substances in a biological fluid and visualization of their presence in the form of staining or fluorescence on a test strip, according to the "yes-no" principle.
Usually, in order to obtain quantitative results and make a diagnosis, it is necessary to use special portable tools, for example, a reflective photometer that allows recording the intensity of staining of the test area. And the speed of diagnosis is extremely important for starting therapy in cases of acute myocardial infarction, sepsis or malignant neoplasms.
The scientific team, led by Senior researcher of the Department of Functional Nanosystems and High-temperature Materials of NUST MISIS, K.H.N. Alexander Osipov, managed to combine the qualitative and quantitative principles of the immunochromatographic test in a simple and effective bioanalytical system, thereby increasing the quality and accuracy of their results.
"We have improved the technology used for rapid tests: now it is possible not only to detect the presence of certain substances in the body, but also to visually determine their critical amount. To get a quantitative result, you need to put one or several drops of a bio-sample on the test strip and simply count the number of colored test lines appearing in the analytical zone of the device," said Alexander Osipov, senior researcher at the Department of Functional Nanosystems and High–temperature Materials at NUST MISIS.
"The biological fluid flows onto a segment of the test strip containing a conjugate (hybrid molecule) of antibodies labeled with gold nanoparticles or quantum dots, captures it and moves with it along the analytical membrane. The resulting labeled immunocomplexes pass through several transverse lines containing second antibodies sorbed in increasing concentrations against the determined antigen. Due to specific antibody-antigen interactions, labeled immunocomplexes bind on the carrier, which is visually recorded in the form of colored transverse test lines. The higher the content of the substance to be determined in the sample, the greater the number of lines appears in the analytical zone. Such an approach when analyzing, for example, human chorionic gonadotropin in urine makes it possible to determine not only the presence, but also the duration of pregnancy," the expert explained.
"The use of new types of nanoscale gold particles or quantum dots in a conjugate with antibodies in the form of so-called "nanowells", "stars", "popcorn", "flowers" can significantly increase the detection limit of the analyzed substances in biological fluids. This is fundamentally important when analyzing markers of a number of deadly diseases, for example, procalcitonin for the detection of sepsis.
When diagnosing a heart attack, the protein binding fatty acids (c-BSFA) is the most promising as an early cardiomarker. With damage to the myocardium – the heart muscle – the concentration of c-BSFA in the blood increases significantly in the first hours after the appearance of pain symptoms. Simultaneous determination of early (c-BSFA) and late (troponin I) cardiomarkers using a new type of rapid test increases the effectiveness of diagnosis and allows you to identify hidden forms of heart attack," he said.
The prompt and very easy-to-use method can be used even in an ambulance or at home. A batch of experimental test samples is currently undergoing preclinical testing.
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