Novel optical biosensors based on Si nanowires for determining cancer, metabolic and oxidizing stress indicators

The project aims at the development of optical biosensors for the immunochemical detection of cancer markers and markers of oxidative stress both proteins and low molecular weight analytes. The detection is based on Raman spectroscopy and photoluminescence (PL). For the enhancement of the detection sensitivity, Si substrates with an array of vertical nanowires will be fabricated, on which metal nanoparticles will be deposited in order to enhance the Raman signal of the substances. This method of detection is called SERS (surface-enhanced Raman scattering). Under optimal conditions the Raman signal can be enhanced by a factor of 106 to 1014. The sensitivity of the method will be assessed through the use of SERS substrates for the immunochemical determination of three cancer markers, which are related mainly to gynecological cancers, the cancer antigen 125 (Ca-125), human epididymis protein 4 (HE4) and survivin or BIRC5 (baculoviral inhibitor of apoptosis repeat-containing 5). The combined detection of these three biomarkers is expected to enable early diagnosis and staging of ovarian cancer, contributing to the survival of the patient and the avoidance of relapse. It is worth noting that there is no screening process contributing to the prevention of ovarian cancer so far. The use of the proposed SERS substrates for the immunochemical determination of the three cancer markers is expected to increase the sensitivity of the detection relative to the exiting immunochemical techniques (ELISA, chemoluminescence) and decrease the analysis duration and cost. Additionally, in the frame of the project, methods for the selective detection of characteristic oxidative stress markers in saliva will be developed and evaluated regarding their sensitivity and specificity.

The main objectives of the project can be summarized as follows:

  1. Fabrication of sensitive SERS substrates based on Si nanowires made by MACE and covered with metal nanoparticles of optimal size and density.
  2. Novel high sensitivity technique for the detection of three biomarkers related to ovarian cancer diagnosis and staging assessment
  3. Novel sensitive methods of detecting markers related to oxidative stress in saliva
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