11-MUA/Ag Modified Large-Core Fiber-Optic SPR Sensing Probe and Its Highly Sensitive Detection for Rabies Virus

Rabies is a serious disease that causes madness and death in humans and mammals. Therefore, high sensitivity of rabies virus (RV) detection is of vital importance. In this work, an RV fiber-optic biosensor based on reflection structure and surface plasmon resonance (SPR) is designed. The silver film is coated on the surface of 1-cm bare core of the large core fiber to excite the SPR effect, and a 300-nm silver film is evaporated on the end face of the large-core fiber to enhance the light reflection. An 11-mercaptoundecanoic acid (11-MUA) is used to functionalize the carboxyl group onto the surfaced optical fiber, the carboxyl group binds stably to the RV antigen; thus, the sensor detects RV antibody via immunoreaction. The results show that the designed sensor can detect trace RV antibodies in the concentration range of 0.1–103 pg/mL, the sensitivity and the detection limit are 2.10635 and 0.13360 pg/mL, respectively. Furthermore, the sensor shows the excellent sensing performance in the clinical samples.