NUST MISIS scientists have developed a new type of membrane test strip for the quantitative immunochromatographic rapid-test that will be able to accurately and quickly make an early diagnosis of an acute myocardial infarction through the presence of disease markers in blood, as well as to identify various things such as sepsis, a pregnancy’s duration, and viral & bacterial infections.
The development of new methods and devices which allow medical professionals to rapidly analyze mixtures of biologically active compounds is one of the main focuses in analytical biotechnology today. Requirements such as an analysis’s speed of implementation, high sensitivity, and low cost all apply to these methods. Tests based on immunochromatography (the most popular of which is a pregnancy test) are extremely easy to use. They are based on the detection of individual substances in biological liquids and the visualization of their presence in the form of coloring or fluorescence on the test-strip, on the “yes-no” principle.
Usually, to obtain quantitative results and make a diagnosis, it is necessary to use special portable tools, such as a reflecting photometer, to register the intensity of coloring in the test zone. The diagnosis’s speed is vital to start treatment immediately in cases of acute myocardial infarction (a serious heart attack), sepsis, and malignant transformations.
The science team led by Alexander Osipov, Candidate of Chemical Sciences and Senior Fellow at the NUST MISIS Department for Functional Nanosystems & High Temperature Materials, has managed to combine qualitative and quantitative immunochromatographic test principles in a simple and effective bioanalytical system, thus improving the quality and accuracy of their results.
“We have improved the technology used for rapid testing: it is now possible to not only identify the presence of certain substances in the body but also to determine their critical number visually. To get a quantitative result, it is necessary to apply one or several drops of a biosample to the test strip and count the number of colored test lines appearing in the device’s analytical area”, said Alexander Osipov, Senior Fellow at the NUST MISIS Department for Functional Nanosystems & High Temperature Materials.
“Biological fluid flows on the test strip segment that contains a conjugate (hybrid molecule) labeled with gold nanoparticles or quantum dots of antibodies, then [the test strip] captures it and moves with it along an analytical membrane. The resulting immunocomplexes move along several cross lines containing a second set of antibodies against the defined antigens in increasing concentrations. The binding of labeled immunocomplexes on the carrier, which is visually registered as forms of colored cross lines [on the test strip] takes place due to the specific interactions of ‘antibody-antigen’. The higher the content of the determining substance in the sample, the greater the number of lines that will appear in the analytical area. Using this approach to analyze, for example, human chorionic gonadotropin in urine, allows us to determine not only the presence but also the stage of a pregnancy”, Osipov explained.
“The use of new types of nanosize gold particles or quantum dots in conjugate with antibodies in the form of so-called ‘nanoclouds’, ‘stars’, ‘popcorn’, and ‘flowers’ allows us to significantly increase the detection limit of analyzed substances in biological fluids. This is fundamentally important in the analysis of the markers of a number of deadly diseases; for example, we can see these processes at work using procalcitonin to detect sepsis. [Monitoring] fatty-acid-binding proteins (FABP) is the most promising way to diagnose early heart attacks. When myocardium (the heart muscle) is damaged, the concentration of FABPs in the blood increases significantly in the first hours [after feeling pain]. The simultaneous determination of early FABP and late (tropotin I) Cardiac markers with the use of our new type of rapid-test increases the efficiency of diagnoses and allows doctors to identify hidden forms of heart attacks”, he concluded.
The method, which is quite active and easy to use, can be applied in an ambulance or even at home. A batch of experimental test samples is currently undergoing pre-clinical trials.