DEVELOPMENT OF NUCLEIC ACID AND NANOMATERIAL BASED ELECTROCHEMICAL BIOSENSORS AND THEIR APPLICATIONS FOR CANCER DIAGNOSIS
Project no. 24070 · Status: Kapanmış (Yayın bekleniyor) · 2022
Summary
<p>In this thesis, an alternative diagnostic method based on electrochemical nanobiosensor (nanoaptasensor) has been developed for cancer diagnosis. Electrochemical biosensors are used in a wide variety of fields today, as they are sensitive, fast, selective, miniaturized, portable, easy to use and economical devices.</p><p>Within the scope of the thesis study, the presence of human epidermal growth factor receptor 2 (HER2), an established cancer biomarker, in breast cancer cell line MCF7 and lung cancer cell A549 was determined with developed biosensor technologies. Breast cancer is one of the most common cancer types in women around the world. More than 90% of these deaths are associated with metastatic growth. Therefore, detecting cancer at an early stage is very important to increase the chances of survival. HER2 actually plays a role in normal growth and cell differentiation. However, a malignant growth is associated with overexpression of HER2. Therefore, early diagnosis of this expression indicating the development of cancer, that is, determination of low HER2 level with effective methods, is important in order to start treatment early.</p><p>For the fast, cheap, sensitive and selective determination of HER2, electrochemical DNA biosensors were designed separately by using a pencil graphite electrode (PGE) and then carbon black (CB) and carbon nanotube (CNT) electrodes with appropriate types of PLA additives produced via a three-dimensional printer. Before biosensing studies, optimization studies were first carried out for 3D electrodes. Then, the HER2 aptamer containing the electroactive label was immobilized on the electrode surfaces, and electrochemical measurements for the detection of low HER2 levels in MCF-7 and A549 cancer cells were performed by using differential pulse voltammetry (DPV) technique. The results obtained from the developed PGE and 3D electrode-based biosensors were compared with each other. In the study, in low level HER2 analysis, concentrations of 106 cells/20 μL for PGE and 106 cells/10 μL for 3D electrodes were determined as the optimum conditions, respectively. In the thesis, three different types of biosensors that are sensitive to detect changes in even low HER2 levels and can be determined through aptamer-cell interaction have been developed and their applicability in cancer diagnosis has been demonstrated. With this study, an alternative diagnostic method for the healthcare field has been developed that provides results in a short time and can be analyzed without the need for expensive kits and expertise.</p>