Sensitivity enhancement of fiber-optic SMOX sensor using gold film-AuNPs-antibody three layers structure

A Spermine Oxidase (SMOX)detection local surface plasmon resonance/surface plasmon resonance (SPR/LSPR) optical fiber sensor was constructed with a three-layer structure consisting of gold film/gold nanospheres (AuNPs)/SMOX-antibody in this study. The detection of SMOX was achieved through the specific binding of immobilized antibodies to free antigens in a buffer solution. The AuNPs were immobilized on Gold Film by 1,6-Hexanedithiol (DMH) linker to enhance the sensitivity of optical fiber probe from 1821.21 to 2204.97nm/RIU. The Zeta potential and Fourier Transform Infrared Spectroscopy (FTIR) indicated that the SMOX antibody was attached to the surface of the optical fiber probe by physisorption to construct a SMOX sensor. The SMOX-detection experimental data conformed to the Langmuir model with an R 2 value of 0.92, a lower limit of detection of 0.625μg/ml and exhibited excellent selectivity, high stability, and a rapid response time of 12 min. This method provides a new concept for SMOX detection and has a broad application prospect in the field of biomedical diagnosis.