Determination of specific biomarkers with disposable biosensor systems and investigation of useage in cancer early diagnosis

Cancer is known as a disease of epoch and it threats human health significantly. The identification and determination of biomarkers has a significant role in the early stage of cancer. Biomarkers are present in saliva, serum, plasma and tissue. Therefore, the early detection of cancer is possible by measuring cancer biomarkers in biological fluids. The biomarker measurement is usually performed in serum samples. However, recent research has displayed that a variety of protein ingredients in blood are also present in saliva. Saliva, has attracted attention due to being easily accessible biological fluid. The collection, storage and transfer of saliva samples is easy. The analysis of saliva provides a desirable and promising platform for the diagnosis of different types of cancers. Consequently, the accurate and sensitive detection of cancer biomarkers facilitates the treatment of cancer. In this thesis, six different biosensors have been produced to detect cancer biomarkers in body fluids. Each biosensor is fabricated with different electrode designs. Interleukin-1a, interleukin-1 and interleukin-8 are the cancer biomarkers targeted for analysis. 6-phosphonohexanoic acid (PHA), 3-phosphonopropionic acid (PHP), 3- (triethoxysilyl) propyl isocyanate (IPTES), linear polymer poly (glycylmethacrylate) and Super P-poly (glycylmethacrylate) polymer composite interface materials. Anti-interleukin 1α, anti-interleukin 1β and anti-interleukin 8 were used as biorecognition elements. The modifications performed on the electrode surface are characterized by electrochemical techniques (electrochemical impedance spectroscopy, alternating voltammetry) and morphological techniques (scanning electron microscopy, atomic force microscopy). Single frequency impedance measurements were also performed to monitor the interaction between the antibodies and the antigens. Repeatability, reproducibility, shelf life, reusability of biosensors has also been monitored. In addition, biomarker deteminations were performed in serum and saliva samples to monitor the clinical success of biosensors. Whether the ELISA test is required or the standard addition method proves the success of the biosensor.