Graphene oxide functionalized long period grating for ultrasensitive label-free immunosensing

Abstract

We explore graphene oxide (GO) nanosheets functionalized dual-peak long period grating (dLPG) based biosensor for ultrasensitive label-free antibody-antigen immunosensing. The GO linking layer provides a remarkable analytical platform for bioaffinity binding interface due to its favorable combination of exceptionally high surface-to-volume ratio and excellent optical and biochemical properties. A new GO deposition technique based on chemical-bonding in conjunction with physical-adsorption was proposed to offer the advantages of a strong bonding between GO and fiber device surface and a homogeneous GO overlay with desirable stability, repeatability and durability. The surface morphology of GO overlay was characterized by Atomic force microscopy, Scanning electron microscope, and Raman spectroscopy. By depositing the GO with a thickness of 49.2 nm, the sensitivity in refractive index (RI) of dLPG was increased to 2538 nm/RIU, 200% that of non-coated dLPG, in low RI region (1.333-1.347) where bioassays and biological events were usually carried out. The IgG was covalently immobilized on GO-dLPG via EDC/NHS heterobifunctional cross-linking chemistry leaving the binding sites free for target analyte recognition. The performance of immunosensing was evaluated by monitoring the kinetic bioaffinity binding between IgG and specific anti-IgG in real-time. The GO-dLPG based biosensor demonstrates an ultrahigh sensitivity with limit of detection of 7 ng/mL, which is 10-fold better than non-coated dLPG biosensor and 100-fold greater than LPG-based immunosensor. Moreover, the reusability of GO-dLPG biosensor has been facilitated by a simple regeneration procedure based on stripping off bound anti-IgG treatment. The proposed ultrasensitive biosensor can be further adapted as biophotonic platform opening up the potential for food safety, environmental monitoring, clinical diagnostics and medical applications.

Graphene-Oxide-Coated Long-Period Grating-Based Fiber Optic Sensor for Relative Humidity and External Refractive Index

“…Further refinement can come from the variation of the period of the grating, to achieve a higher sensitivity, as higher order modes are bound to be more sensitive to the external RI. Another potential approach is to functionalize the GO layer deposited on the fibre surface with various molecules with functional groups or bio-molecules, to develop highly selective chemical and bio chemical fibre optic sensors [22]. Furthermore, GO could be reduced to achieve the characteristics of graphene by applying a chemical or thermal reduction process and in that way, reduced GO could add another dimension to optical fibre sensors, as has been introduced by Sridevi et al in [23].…”

Graphene Oxide as an Optical Biosensing Platform: A Progress Report

“…[87] Consequently, temperature and GO oxidation degree should be carefully controlled in these approaches. [92] In fact, the GO-coated fiber approach showed a limit of detection tenfold lower than that of the noncoated fiber. [87][88][89] Although label-free optical biosensing platforms have been reported to be enhanced by using structural properties of GO, as far as we are concerned, the elucidation of the optical/photonic properties or phenomena underlying such improvements have been scarcely elaborated until now, which can be subject of in-depth investigation.…”

“…[108][109][110] iii) The ability to anchor organic compounds utilizing π-π stacking interactions for highly sensitive analysis. [92] Copyright 2017, Elsevier. [114] Interestingly, the 2D character of GO facilitates www.advmat.de www.advancedsciencenews.com engineering of advantageous 3D SERS substrates with different numbers of AgNp layers intercalated, showing from picomolar to femtomolar sensitivity.…”

Black phosphorus integrated tilted fiber grating for ultrasensitive heavy metal sensing

“…However, the grand challenge of film deposition on optical fiber is from its cylindrical geometry and such a thin diameter. The recent exploitation reveals that 2D layered materials could modulate light with superior performance for realistic applications in ultrafast lasers, broadband polarizer, gas detection, humidity sensor, and biosensing [6,7,[33][34][35][36].…”