Label-free detection of breast cancer biomarker using silica microfiber interferometry

Sensitive detection of HER2 biomarkers is critical for clinical diagnostics of breast cancer while such detection is quite challenging due to the rapid detection of low concentration of HER2 biomarkers in complex biological media. A compact and label-free optical fiber sensor based on silica microfiber interferometry for detecting HER2 in serum has been proposed and experimentally demonstrated. The antibodies immobilized on the microfiber surface play the roles of the specific immuno-tentacles on catching the HER2 targets. The change of the surface refractive index attributed to the immunoreactions could be captured by the optical fiber sensor and transduced into a significant wavelength shift in the interferometric fringe. The proposed fiber-optic biosensor shows an improved sensitivity of 0.1 nm/(ng/mL), even in a serum matrix. The advantages of simple detection scheme and ease of miniaturization might make the biosensor a promising platform for clinical cancer diagnosis and prognosis.