DEVELOPING AN OPTICAL FIBER BIOSENSOR FOR THE DETECTION OF CD44 PROTEIN WITH BREAST CANCER CELLS

Abstract

CD44, the transmembrane glycoprotein functions as a cancer stem cell biomarker, as it supports cell attachment as well as cell movements, leading to tumor cell progression. The excessive overexpression of CD44 is strongly associated with unfavorable cancer progression and metastasis in several cancer types such as breast cancer. Existing detection methods for CD44 such as ELISA and immunohistochemistry together with Western blotting face limitations in both processing complexity and time requirements. Additionally, they are limited in terms of sensitivity. Optical fiber biosensors provide researchers with a sensitive method that performs real-time label-free measurements. This thesis project describes and discusses the fabrication, calibration, and detection processes of a novel optical fiber biosensor which detects CD44 through commercially sourced cell lines. The sensor worked with anti-CD44 antibodies at its surface while testing sucrose-based refractive index standards which yielded 125.23 dB/RIU sensitivity. A sensor detection procedure used three human cell lines: HCC1806 with CD44 expression and MCF10A without it as well as HEK293 with no CD44 expression. The sensor demonstrated high sensitivity to HCC1806 cells through a distinct intensity decrease at 1544.416 nm (3.315 dB) but revealed minimal detection of MCF10A cells (0.110 dB) thus proving its specific detection capabilities. Research progressed to evaluate non-specific interactions after HEK293 cells produced signal magnitude of 2.289 dB. The sensor system proved its capability to function as a specific tool for quick detection of CD44-expressing cells thereby opening prospects for future cancer screening and metastasis monitoring.