Circulating cancer cell detection using an optical fiber aptasensor

The detection of circulating tumor cells (CTCs) represents an important goal in oncological diagnosis and treatment, as CTCs are responsible for metastasis in several forms of cancer and are present at very low concentration. Their detection should occur at around 1-10 cells/mL of blood for diagnosis purpose. In this work, we propose an all-fiber plasmonic aptasensor featuring multiple narrowband resonances in the near-infrared wavelength range to detect metastatic breast cancer cells. To this aim, specific aptamers against mammaglobin-A proteins were selected and immobilized as bioreceptors on the optical fiber surface. In vitro assays confirm that label-free and real-time detection of cancer cells (LOD of 49 cells/mL) occurs within 5 minutes, while the additional use of functionalized gold nanoparticles allows a two-fold amplification of the biosensor response. Differential measurements on selected optical resonances were used to process the sensor response and results were confirmed by microscopy analysis. The detection of only 10 cancer cells/mL was performed with relevant specificity against non-target cells with comparable sizes and shapes.