Gold Nanoparticle-Enhanced SMS Fiber Optic Sensor for Enzymatic Detection of Ascorbic Acid

Ascorbic acid, commonly called vitamin C, is a major biomarker of many malfunctions and deficiencies in the human body. This research focuses on enhancing ascorbic acid detection sensitivity using a specialized (single-mode, multimode, and single-mode) SMS fiber structure through enzyme functionalization and leveraging localized surface plasmon resonance (LSPR). The SMS fiber structure, designed for versatility, was modified to increase selectivity by ascorbate oxidase functionalization, which oxidizes the AA in the presence of oxygen, while LSPR techniques were employed to harness plasmonic effects for improved detection capabilities using gold nanoparticles (AuNPs), whose absorbance peak wavelength appeared at 522.8 nm. The resulting sensor probe was examined for various concentrations of AA ranging from 50 to 120 µM in terms of different performance parameters such as sensitivity, limit of detection, selectivity, reproducibility, and repeatability for ascorbic acid detection and such studies could be employed in complex biological matrices for AA detection. The sensor demonstrated a sensitivity of 0.0138 nm/μM and a calibration correlation factor of 0.9181, good linearity over the range of 50–120 µM AA concentrations. Additionally, the resulting fiber structure displayed selective detection of AA, thus ensuring non-interference of other analytes present in the realistic biological matrix. This research holds promise for advanced applications in clinical diagnostics and biomedical research, offering a novel and effective approach to enhance ascorbic acid detection.