Diagnosing various types of cancer at an early stage is vital to their effective treatment and is a major challenge for the scientific community. One of the approaches followed to achieve this goal is the determination of various biomarkers in biological fluids and mainly in blood serum. In particular, for the diagnosis of gynecological cancer and especially of ovarian cancer, the determination in serum of the following three biomarkers has been proposed: cancer antigen 125 (Ca-125), human epidermal secretory protein 4 (HE4), and survivin or BIRC5 (baculoviral inhibitor of apoptosis repeat-containing 5). The combined determination of these three biomarkers is expected to help both in the initial diagnosis of ovarian cancer and in the categorization of ovarian tumors, contributing significantly to the overall survival and prevention of the disease recurrence. Simultaneous determination of cancer markers in a human serum sample with low cost, high sensitivity and reliability can be achieved by appropriate biosensors and more specifically immunosensors. Optical immunosensors offer higher detection sensitivity than other types of sensors and, in addition, allow for the simultaneous detection of multiple analyzers and are subject to less interference from the sample matrix compared to other types of sensors allowing real-time detection of analytes in human serum. The project will develop optical immunosensors for the detection of the three cancer markers, Ca-125, HE4, and survivin based on the principle of Surface-Enhanced Raman Scattering (SERS) . The use of SERS substrates as solid carriers for the immunochemical assay of the three cancer markers is expected to increase the detection sensitivity relative to standard immunochemical techniques. The work to be carried out in the project includes: the development of non-competitive enzyme-linked immunoassays in microtiter wells for the three targeted biomarkers, development of sensors on SERS substrates for each one of the three biomarkers separately, and finally the development of sensors on SERS substrates for the simultaneous determination of the three biomarkers in a single run. The work is carried out in the context of the execution of the project BioNanoDiagnostiki (Τ2ΕΔΚ-03746) and is the subject of the doctoral thesis of Mrs. Georgia Gkeka. The experimental part of the work will take place at the Laboratory of Immunoassays-Immunosensors of IPRETEA in collaboration with the Department of Microelectronics of the Institute of Nanoscience & Nanotechnology of NCSR “Demokritos” and the Chemistry Department of the University of Athens (Prof. A. Economou).