Thrombin detection by means of an aptamer based sensitive coating fabricated onto LMR-based optical fiber refractometer

An optical fiber sensor using an aptamer receptor has been developed for the detection of thrombin. The sensitive coating consists of an aptamer-polymer structure fabricated using the layer-by-layer electrostatic self assembly technique onto novel optical fiber refractometers based on lossy mode resonances (LMRs). LMR based refractometers enable to overcome the traditional drawbacks of surface Plasmon resonance (SPR) based devices, such as the utilization of polarized light for example. The refractometer is based on an indium tin oxide thin layer deposited by DC-sputtering onto the cladding removed multimode fiber. These refractometers enable to monitor the variations of the surrounding medium refractive index (RI). Hence, RI variations of the outer film induced by thrombin can be referenced to the LMR wavelength shift. The described configuration has enabled the detection of low concentrations of thrombin (100nM) as well as obtaining a maximum wavelength shift of 50 nm at higher (1μM) concentrations.