A PDA/AuNPs/PDANPs Sandwich Structure Modified Fiber Optic SPR Biosensor for High Precision and Specific Detection of Rabbit IgG

A polydopamine (PDA)/gold nanoparticles (AuNPs)/PDA nanoparticles (PDANPs) sandwich structure modified optical fiber surface plasmon resonance (SPR) biosensor for specific detecting of rabbit IgG was proposed in this article. On the proposed sensor, PDA, AuNPs, and PDANPs were sequentially deposited to form a multilayer hybrid structure. The refractive index (RI) sensitivity of the sensor has been significantly enhanced through the strong coupling effects of SPR and localized surface plasmon resonance. The sensor achieves an RI sensitivity of 3009.58 nm/RIU, representing a threefold increase compared with the original SPR sensor. In addition, due to the high surface activity and large specific surface area of PDANPs, the biosensitivity of the sensor has been enhanced. The sensor demonstrated specific detection of rabbit IgG with a biosensitivity of 0.9157 nm/(<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>g/mL) and limit of detection (LOD) of 22 ng/mL. These findings indicate that the prepared sensor can specifically detect rabbit IgG with high precision and a low LOD. Therefore, this PDA/AuNPs/PDANPs sandwich structure modified biosensor has great potential in clinical detection and other biodetection fields.