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).

Food quality and safety assessment is of major importance to both the food industry, the food producers and the consumers. For some foods, such as milk, it is necessary to test both the material and the processed products against harmful substances as quickly as possible. Such tests include the detection of aflatoxin M1 (AFM1), as well as of several pathogenic bacteria including Salmonella spp., Escherichia Coli O157: H7, Staphylococcus aureus, Bacillus cereus and Listeria monocytogenes. AFM1 is one of the most carcinogenic and toxic aflatoxins produced by fungi and therefore the European Union has set very strict maximum allowable limits for AFM1 in food. Simiral limits have been set regarding microorganisms in food for which in many cases the presence is completely prohibited due to the seriousness of the problems they might cause to human health. The detection of various harmful substances in food is carried out by analytical methods that are characterized by high sensitivity and accuracy, however they are quite time consuming, require expensive equipment and cannot be used for field analysis. For this reason, the use of immunosensors, and in particular optical immunosensors, has been explored as alternative that could replace existing methodologies. Optical immunosensors are divided into two categories, those that require the use of labels to detect the substance to be determined and the label-free ones. In the latter category are included those based on Mach-Zehnder interferometry. In this context, the project aims to develop optical immune sensors for the detection of harmful species (e.g., mycotoxins, bacteria) in food. More specifically, an immersible photonic chip is developed in which two interferometers are realized, one working and one reference interferometer. The sensor arm of the reference interferometer will be coated with an inert protein, while the sensor arm of the working interferometer will be modified with the toxin or microorganism whose detection in milk is targeted, following a competitive immunoassay. The chip integrates the complete Mach-Zehnder interferometers photonic circuit but the optical coupling and signal recording is done via a double optical fiber that connects the chip input with a white light source and its output with a digital spectral analyzer. For analysis, the chip will be immersed in a solution containing the sample and specific antibodies against each analyte without the need for microfluidic cells. The work is carried out in the context of the execution of the FOODSENS project (Τ2ΕΔΚ-01934) and is the subject of the doctoral thesis of Mrs. Dimitra Kourti. The experimental part of the work is carried out at the Immunoassays-Immunosensors Laboratory of IPRETEA in collaboration with the Department of Microelectronics of the Institute of Nanoscience & Nanotechnology of NCSR “Demokritos” and the Department of Chemistry of the University of Athens (Prof. A. Economou).

Mycotoxins are chemical compounds produced by various families of fungi and belong to a class of substances whose concentration must be determined in several categories of food due to their negative effects on human health as these compounds present, each to varying degrees, hepatotoxic, immunosuppressive, mutagenic and/or carcinogenic effects. In order to ensure the good quality of food, continuous control is required at all stages of their production and processing to verify absence of mycotoxins. However, due to the large volume of samples, it is practically impossible to analyze them in a short period. Therefore, there is a need for methods and devices capable of accurately identifying groups of harmful substances outside the laboratory. Biosensors are detection devices that can meet these needs as they enable the simultaneous identification of multiple analytes in a sample and at the same time, they can be integrated into small size devices. In this context, the aim of the project is to develop an optical biosensor for the simultaneous identification of three mycotoxins, namely Aflatoxin B1, Fumonisin B1 and Deoxynivalenol in cereal samples. The choice of the three mycotoxins was due to the fact that they are one most commonly encountered in cereals as well as due to their high toxicity. Simultaneous determination of the targeted mycotoxins is pursued through the development of an immunosensor based on White Light Reflectance Spectroscopy using silicon chips with multiple reactive areas made of silicon dioxide layer with different thickness. Each of these regions is activated by a protein conjugate of a different mycotoxin. The reflection spectrum received from all regions during the immune responses is analyzed by appropriate processing into the individual spectra allowing the reactions that take place in each region to be monitored separately without the need for moving optical components. The experimental part of the thesis is performed in the Immunoassays/Immunosensors Lab of INRASTES in collaboration with the Chemistry Department of the University of Athens (Prof. A. Economou).

Sepsis, one of the leading causes of death worldwide, occurs when a local microbial infection spreads into blood circulation triggering a vigorous inflammatory response. This response can result in multiple organ failure, which is usually fatal. Thus, early diagnosis is the only way to increase the survival rate. The aim of this project is the development of a multi-analyte optical label-free biosensor based on White Light Reflectance Spectroscopy (WLRS) for sepsis diagnosis through the rapid and accurate determination of a panel of three markers related to sepsis in blood serum samples. The targeted markers are C-reactive protein, procalcitonin and inteleukin-6. The simultaneous determination of these markers is essential to early sepsis diagnosis. In combination with the overall clinical picture of the patient could help to manage successfully the treatment. The main objectives of the project are the development of: a) label-free assays for the three targeted analytes that will be characterized by high accuracy and dynamic range covering not only the pathological serum concentrations but also the concentration range of healthy individuals, b) sensors capable for the simultaneous determination of the three analytes in the same sample by appropriate structuring and biofunctionalization of the biosensor surface, and c) a prototype instrument and accompanying software for the acquisition and processing of the signals obtained from the different assays and presentation to the final user in a concise and easy to interpret format. The project is realized in the frame of the PhD thesis of Mrs. Dimitra Tsounidi, who is the recipient of a Stavros Niarchos Foundation Industrial Fellowship in collaboration and with co-founding from the company ThetaMetrisis S.A. The experimental part of the thesis is performed in the Immunoassays/Immunosensors Lab of INRASTES in collaboration with the Chemistry Department of the University of Patras (Prof. Th. Christopoulos).