Posted in | Quantum Dots

Rapid-Tests on Quantum Dots Enable Fast, Accurate Diagnosis of Heart Attack and Sepsis

A new type of membrane test strip has been developed by NUST MISIS researchers to achieve innovative and quantitative immunochromatographic rapid-tests. The test strip can be used for making an early diagnosis of acute myocardial infarction quickly and accurately, via the presence of disease markers in blood. The test strip can also be used for identifying other things such as viral and bacterial infections, sepsis and the stage of a pregnancy.

Image credit: NUST MISIS

One of the major focuses in present analytical biotechnology is the development of innovative devices and techniques, which enable medical professionals to quickly study mixtures of biologically active compounds. Requirements like high sensitivity, the speed of implementation and a low cost are relevant to these techniques. Tests based on immunochromatography (the pregnancy test is the most popular) can be used very easily. In these tests, individual substances are detected in biological liquids and their presence is visualized in the form of fluorescence or coloring on the test-strip; the “yes-no” principle.

To achieve quantitative results and make an accurate diagnosis, unique portable tools, such as a reflecting photometer, often need to be used to record the intensity of coloring in the test zone. In cases of sepsis, acute myocardial infarction (a serious heart attack) and malignant transformations, the speed of diagnosis is important to initiate treatment immediately.

The science team, headed by Alexander Osipov, Candidate of Chemical Sciences and Senior Fellow at the NUST MISIS Department for Functional Nanosystems & High-Temperature Materials, has successfully combined quantitative and qualitative immunochromatographic test principles in an effective and simple bioanalytical system; enhancing the accuracy and quality 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.

Alexander Osipov, Senior Fellow at 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.

Alexander Osipov, Senior Fellow at NUST MISIS Department for Functional Nanosystems & High-Temperature Materials

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.

Alexander Osipov, Senior Fellow at NUST MISIS Department for Functional Nanosystems & High-Temperature Materials

The relatively active and easy-to-use method can be applied in both ambulance and home settings. Presently, a set of experimental test samples is undergoing pre-clinical trials.

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