Prylutskyi M. Development of biosensor platforms and basic analysis algorithms for express diagnostics of breast cancer in vitro

The Thesis describes the development of a method for the determination of polyamines in the culture of MCF-7 cells and in the blood serum of patients with breast cancer and study of the biological properties of polyamines as potential markers of breast cancer. To compare the efficiency of newly created biosensor platform, several types of biosensor devices were used, in which a different approach for sensitizing the surface of the transducer was applied. Several types of transducers with different surface coatings have also been used to determine an effective platform for polyamine determination. At the beginning of research to create an effective biosensor platform, it was decided to compare the effectiveness of several algorithms of to determine the most sensitive and effective approach. Among all the used analysis algorithms, the highest efficiency was shown by the "direct" approach, in which specific antibodies and polyamines were immobilized directly on the surface of the transducer. The next step was to determine the limits of the biosensor sensitivity with a direct analysis algorithm. The biosensor sensitivity range was 5-1000 ng/ml. The efficiency of the assay improved after modification of the transducer surface with additional substances, which made it possible to increase the sensitivity of the transducer surface, orient antibodies to polyamine-specific sites, and block non-specific binding sites. The efficiency of the biosensor analysis method based on the SPR effect was compared with a biosensor based on photoluminescence of zinc oxide. The biosensor based on the effect of surface plasmon resonance turned out to be the best in the determination of polamines in model solutions and cell culture of the human breast cancer cell line MCF-7 by 14-30% in comparison with the biosensor based on photoluminescence of zinc oxide. In addition, a gold-based transducer is able to detect polyamines in cell culture and model solutions 1.5-2 times better. The correspondence of the displacement of the resonance angle of the biosensor to the concentration of polyamines in the analysis of blood serum samples from patients with breast cancer was studied. The concentration of polyamines in the control blood serum did not exceed the limits of 5-10 ng/ml, and in the blood samples of patients with breast cancer, the concentration of polyamines was in the range of 20-100 ng/ml, which exceeds physiological levels. Based on the results obtained, a biosensor method has been developed that can detect both low and high concentrations of polyamines. The new biosensor platform can determine the presence and concentration of polyamines in solution and in cell culture in vitro at nanomolar concentrations, as well as in blood serum, which makes it relevant and promising for further improvement and use.