An Optical Fiber Immunosensor With a Low Detection Limit Based on Plasmon Coupling Enhancement

An optical fiber immunosensor with a low detection limit based on plasmon coupling enhancement is proposed for detecting human immunoglobulin G (IgG). Graphene oxide (GO)-gold nanorod composites are synthesized and modified onto a photonic crystal fiber (PCF) surface coated with a Au film. GO, as a biosensitive layer, is used to decorate the gold nanorods and concentrate target molecules. The experimental result indicates that the refractive index sensitivity is drastically enhanced to 22248 nm/RIU because of plasmon coupling. Correspondingly, the human IgG detection limit decreases to 6 ng/mL. Moreover, the PCF is insensitive to temperature fluctuation, which can further reduce the measurement error.