A novel periodically tapered structure-based gold nanoparticles and graphene oxide - Immobilized optical fiber sensor to detect ascorbic acid

This work presents a study, analysis, design, and characterization of a localized surface plasmon resonance (LSPR) based ascorbic acid (AA) sensor with improved sensitivity compared to those already reported. Various multi-tapered (four, five, and eight tapered) optical fiber sensors (OFSs) have been developed and characterized in this study. Along with these, different nanomaterials (NMs), such as gold nanoparticles (AuNPs) and graphene oxide (GO), are immobilized over the bare probe. Further, NMs immobilized probes are functionalized with ascorbate oxidase. The AuNPs are well studied in the past with the variation in size, shape and surface functionalization and have been found to be well-suited NMs for biosensing applications. On the other hand, GO-based material is equally promising in the nanostructure-based optical sensing due to their broad surface area, high electrical conductivity, good chemical stability, and excellent mechanical behavior. The performance parameters of the proposed sensor, such as sensitivity (8.3 nm/mM), correlation correlator (0.9724), and limit of detection (51.94 mu M) are greatly improved over the previous designs. A wide range of characterization and validation of NMs immobilized structures are reported here. It indicates a great potential in the practical implementation of LSPR based OFSs for routine diagnostics.