Localized Surface Plasmon Resonance- Based Fiber Optic Biosensor for Acetylcholine Detection

Acetylcholine (Ach) is an important neurotransmitter, which mainly acts on the transmission of neural signals. A new optical fiber biosensor for Ach detection was fabricated by the simple electrostatic interaction relying on positive charge functionalized optical fiber and citrate-stabilized gold nanorods (GNRs). The highest SRI of this sensor was 848 nm/RI when the optimization conditions were 50 min of incubation time, $486.98 \mu \text{m}$ of optical fiber diameter, and the 2.63 of aspect ratio (AR). Then, acetylcholinesterase (AchE) was immobilized on the surface of GNRs by the crosslink method to prepare reflective optical fiber sensing probes. The linear range of the optical fiber biosensor for detecting Ach solution was 1– $1000 \mu \text{M}$ with the sensitivity of 0.0108 nm/ $\mu \text{M}$ . Compared with the traditional detection methods, it was more portable, simple, high strength, easy-to-handle, and cost-effective biosensors.