Designs of Electrochemical Biosensors for the Diagnosis of Neurodegenerative Diseases
Project no. 22395 · Status: Kapanmış · 2020
Summary
<p>Within the scope of this thesis; aptamer and antibody-based electrochemical nanobiosensors were designed for rapid, specific, and reliable determination of myelin basic protein (MBP), a biomarker of multiple sclerosis (MS) disease, and their properties were compared. In these designed sensors, disposable graphite electrodes (PGE) coated with graphene oxide (GO) nanomaterial were used as the sensor surface. Using GO for increasing the surface areas of the sensor enabled very sensitive and analyzes with low detection limit to be performed. Nanomodified sensor surfaces were coated with three different aptamer sequences (LJM-5708, LJM-3064, MBPcl3) and antibodies recognizing MBP biomarker and placed to interact with MBP containing solutions. This interaction was visualized by the Electrochemical Impedance Spectroscopy</p><p>(EIS) technique. The selectivity of the designed sensors was evaluated using human serum albumin (HSA), which has the highest content in both cerebrospinal fluid (CSF) and serum. After the optimization studies of the bioreceptors (aptamers and antibody) concentration, interaction time with the biomarker and washing time after interaction, the most suitable conditions for the assay were determined and analyzes were performed in a biological matrix (artificial CSF) containing a mixture of MBP and HSA. Stability analyzes were made under different time and storage conditions and the application of biosensors was confirmed.</p><p>The aptamers used in this study were previously synthesized in a mouse model for therapeutic purposes and were applied for the first time as detection agents for human MBP determination. In total, three aptasensors and one immunosensor were developed in this study with the electrochemical technique applied in the physical converter unit. After optimization studies, capacities of all sensors to bind the target</p><p>molecule were evaluated, and LJM-5708 aptamer-based sensor and immunosensor were found to be the most appropriate. The miniature PGE-based sensors obtained at the end of the study was applied for the determination of MBP in both PBS and artificial CSF with same detection limit (1 ng/mL) and range of detection (1…128 ng/mL). In addition, thanks to electrochemical measurements without the use of any</p><p>marker or indicator, it allows very fast, label-free direct analysis. With this improved new generation aptasensor; in the clinic, especially for the early diagnosis and monitoring of neurodegenerative diseases, the development of a fast-response, reliable, commercialization potential domestic product has been carried out.</p>