Fiber-optic semi-distributed Fabry-Perot interferometer for low-limit label-free detection of CCL5 cancer biomarker

We present an optical fiber label-free biosensor based on a partially stochastic Fabry-Perot interferometer for the detection of CCL5 (CC Chemokine Ligand 5) cancer biomarker. The sensor has a very simple fabrication process, with a splice-and-cleave approach that requires only one splice and a subsequent cleave at the fiber tip. The enhanced backscattering within the Mg-NP fiber paired with the Fresnel reflection at the fiber tip forms a lowfinesse interferometric structure; the inner reflections due to Rayleigh scattering provide an additional layers of phase shifts, forming a semi-distributed interferometer (SDI). The average sensitivity of the SDI sensors has been reported to be 92.5 dB/RIU. Sensors were biofunctionalized for the purpose of detecting CCL5 by means of a silanization process. We report the detection of CCL5 in diluted serum with a sensitivity of 2.947 mRIU for each 10-fold concentration increase and a limit of detection of 17.6 aM.