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.
Highlights
Human immunoglobulin G (IgG) is a kind of large molecule in blood, with a molecular weight of roughly 150 kD and a tetrameric quaternary structure consisting of four peptide chains: two heavy chains (HCs) and two light chains (LCs) [1,2]
An IgG sensor consisting of a graphene oxide (GO)coated-U-bent longperiod fiber gratings (LPFG) inscribed in a two-mode fiber (TMF) was reported with a low limit of detection (23 ng/mL) in the 3–20 μg/mL range [24]
Schematicrepresentation representationofof the surface functionalization of elliptical core helical intermediate-period fiber grating (E-Helix intermediate-period fiber gratings (HIPFGs)): cleaning activating the by piranha solution; (b) generation of silane layer using solution; activating the E-HIPFG by piranha solution; (b) generation of silane layer using APTES solution; (c) treatment with glutaraldehyde solution; (d) immobilization of anti-IgG; (e) blocking the re(c) treatment with glutaraldehyde solution; (d) immobilization of anti-IgG; (e) blocking the remaining maining bonding sites by bovine serum albumin (BSA) solution; (f) human IgG detection and (g) dissociation of antibody
Summary
Human immunoglobulin G (IgG) is a kind of large molecule in blood, with a molecular weight of roughly 150 kD and a tetrameric quaternary structure consisting of four peptide chains: two heavy chains (HCs) and two light chains (LCs) [1,2]. A diffraction grating immunosensor was proposed for specific detection with the LOD of 1.3 × 10− 8 M [13] These methods are either time-consuming or complex processes. An IgG sensor consisting of a graphene oxide (GO)coated-U-bent LPFG inscribed in a two-mode fiber (TMF) was reported with a low limit of detection (23 ng/mL) in the 3–20 μg/mL range [24]. For an immunoassay, most of these optical fiber biosensors need to be combined with extra surface materials and/or multi-fiber architectures, resulting in complicated fabrication procedures that affect stability and weaken coupling strength [21,29] Some of these sensors have a high susceptibility to outside interference, which can impact the stability and the accuracy of the immunosensor. The outstanding resistance to environmental disturbances of the functionalized E-HIPFG is further proved by its low temperature sensitivity, strain sensitivity, and torsion sensitivity
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