D-shape optical fiber probe dimension optimization for LSPR based bio-sensor

Abstract

The evanescent wave absorption based photonic sensing platform has been developed using D-shaped fiber optic probes for refractive index (RI) mediated bio-sensors. The RI sensitivity of this bare probe was established using different sucrose solutions by optimizing the active de-cladded surface area of the fiber. A linear correlation between probe sensing area and RI sensitivity was observed for different probe lengths. Further, these bare probes have been functionalized using amine (–NH2) functional groups on the air-exposed core using the standard silane treatment process. This probe was demonstrated as a localized surface plasmon resonance (LSPR) monitoring platform by immobilizing the spherical gold nanoparticles (AuNPs). The effect of D-shaped length/area on absorption sensitivity was compared with bare and LSPR probes. The biosensing property of this LSPR probe was tested using Immunoglobulin antibody (HIgG). An exponential bimolecular binding kinetic has been observed during this antigen–antibody conjugation and the limit of detection was measured (0.6 µg/mL) by varying concentrations of antigen (GaHIgG). These fiber optic LSPR probes can be integrated into an optical system to develop an evanescent wave absorption-based biosensor.