Fabry–Perot fiber-optic immunosensor based on suspended layer-by-layer (chitosan/polystyrene sulfonate) membrane

A label-free fiber-optic Fabry–Perot interferometric (FPI) immunosensor is proposed by layer-by-layer (LBL) self-assembly of a suspended chitosan and polystyrene sulfonate membrane at the tip of a hollow fiber. Immunoglobulin G (IgG) was immobilized on the polyelectrolyte substrate and the detection of target anti-immunoglobulin G (anti-IgG) was monitored through the measurement of substrate's effective optical thickness. The sensitivity and specificity of the sensor were studied using correlated and non-correlated anti-IgG/IgG pair. Sensitivity of 0.033 μm/(pg/mm2) and limit of detection of 0.005 nM was achieved with the sensor displaying minimal response toward non-correlated anti-IgG. The results demonstrate the feasibility of the sensor for immunosensing.