Molecular profiling of cancer-derived small extracellular vesicles by SERS assay

Cancer-derived small extracellular vesicles (sEVs) have been recognized as a promising biomarker for early cancer diagnosis. Thus, the overall aim of this thesis is to isolate, characterize cancer-derived sEVs from ovarian cancer cell lines and employ surface-enhanced Raman scattering (SERS) assay for molecular profiling of sEVs. Firstly, we demonstrated the isolation of sEVs from 2D cultured A2780-WT (wild-type), A2780-MT (mutant), and OVCAR-3 cell lines, as well 3D cultured A2780-WT and A2780-MT cell lines. Secondly, we characterized the physical properties of sEVs by utilizing nanoparticles tracking analysis (NTA), zetasizer, and transmission electron microscopy (TEM). We found that sEVs are highly heterogeneous (size range of 100–125 nm, and concentration from 1.9x10¹⁰ - 8.9x10¹⁰ particles/mL). We further characterize the molecular features of sEVs by using flow cytometry, Bicinchoninic Acid (BCA) assay, and western blot (WB). We discovered that CA125 and EpCAM expressed on OVCAR3 cell-derived sEVs but not A2780-WT cell-derived sEVs. The SERS assay was employed to profile surface protein (CA125) on sEVs derived from OVCAR3 cell lines, which share similar results as flow cytometry and western blot. This demonstrates SERS assay is a specific and reliable assay. Further studies will be conducted in the PhD project.