All Fiber-Optic Immunosensors Based on Elliptical Core Helical Intermediate-Period Fiber Grating with Low-Sensitivity to Environmental Disturbances

Abstract

An all fiber-optic immunosensor based on elliptical core helical intermediate-period fiber grating (E-HIPFG) is proposed for the specific detection of human immunoglobulin G (human IgG). E-HIPFGs are all-fiber transducers that do not include any additional coating materials or fiber architectures, simplifying the fabrication process and promising the stability of the E-HIPFG biosensor. For human IgG recognition, the surface of an E-HIPFG is functionalized by goat anti-human IgG. The functionalized E-HIPFG is tested by human IgG solutions with a concentration range of 10–100 μg/mL and shows a high sensitivity of 0.018 nm/(μg/mL) and a limit of detection (LOD) of 4.7 μg/mL. Notably, the functionalized E-HIPFG biosensor is found to be insensitive to environmental disturbances, with a temperature sensitivity of 2.6 pm/°C, a strain sensitivity of 1.2 pm/με, and a torsion sensitivity of −23.566 nm/(rad/mm). The results demonstrate the considerable properties of the immunosensor, with high resistance to environmental perturbations, indicating significant potential for applications in mobile biosensors and compact devices.

Recent Developments in the Field of Optical Immunosensors Focusing on a Label-Free, White Light Reflectance Spectroscopy-Based Immunosensing Platform

“…A long-period fiber grating (LPFG) immunosensor that employed an avian antibody (IgY) recognizing Staphylococcus aureus was reported; upon bacteria–antibody interaction, an increase in the bioconjugate thickness and density was created and was tracked as a change of resonance wavelength in the LPFG transmission spectrum [ 68 ]. An all-fiber-optic immunosensor based on elliptical core helical intermediate fiber grating (E-HIPFG) was developed and evaluated through the detection of human IgG after functionalizing the sensor surface with a goat anti-human IgG antibody [ 69 ]. Two immunosensors based on specific antibodies against the Cor a 14-hazelnut allergen and electrochemical or SPR-based optical detection were reported and proposed as a platform for hazelnut allergen analysis in food; mammalian IgG and avian IgY anti-analyte antibodies were immobilized on the gold-coated sensors’ surface, with the latter leading to a better outcome regarding mainly assay specificity [ 70 ].…”

“…Other optical immunosensors have been applied to and/or evaluated for the detection/quantification of specific disease biomarkers, such as neuron-specific enolase [ 56 ], myocardial creatine-kinase [ 80 ], prostate-specific antigen [ 81 ], human epididymis protein 4 [ 57 ], programmed death ligand 1 [ 73 ], cardiac troponin I [ 78 ], and C-reactive protein [ 87 ]. Another group includes optical immunosensors that have been applied to and/or evaluated through the detection/quantification of basic and important biomolecules, such as human INF-γ or insulin [ 62 ], immunoglobulin G [ 69 ], CD5 [ 76 ], collagen I [ 72 ], cortisol [ 74 ], and estrone and estradiol [ 63 ]. On the other hand, other optical immunosensors have been applied to the detection/quantification of exogenous substances, especially natural or synthetic toxic compounds, such as methylamphetamine [ 64 ], ochratoxin A [ 85 ], aflatoxin B1 [ 58 , 67 ], microcystin-LR [ 61 ], zearalenone [ 55 , 79 , 82 ], hazelnut Cor a14 allergen [ 70 ], imidacloprid [ 77 ], carbendazim [ 86 ], and ricin and abrin [ 75 ].…”