Development of novel methods based on surface-enhanced raman scattering for the detection of cancer protein biomarkers

The development of active platforms used in surface-enhanced Raman scattering (SERS) experiments is of great importance. High enhancement factor on active surfaces, good reproducibility, low cost, robustness, ease of preparation, and compatibility with different samples are among the preferred features of SERS. In this thesis, robust, flexible, and highly reproducible diatom-based SERS platforms were prepared using the layer-by-layer assembly method. Single and multiplex detection of cancer protein biomarkers was performed using both label-free and labeled approaches. The SERS enhancement factor of the diatom surface containing 5-layer silver nanoparticles (AgNPs), which has the highest SERS activity among the SERS active platforms with high reproducibility, was determined to be at least 105. PCA analysis indicates that the obtained spectra can be used for label-free biomarker detection. Additionally, the chromatographic separation of the biomarker mixture was performed using SERS as the active stationary phase, followed by multi-detection based on SERS In the labeled approach, SERS-based immunosensors were prepared using antibodies specific to proteins, and both single and multiplex detection of cancer biomarkers were performed with Raman probes. With the single approach, the concentration of each biomarker was detected down to 0.1 ng/mL. Two different approaches were applied within the multi-detection, and Raman mapping was performed for each approach, successfully identifying the biomarkers.