title: 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 49.2nm, the sensitivity in refractive index (RI) of dLPG was increased to 2538nm/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 7ng/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.
authors.affiliation: School of Electronic Engineering, Bangor University, Bangor LL57 1UT, United Kingdom.
authors.forename: Chen
authors.initials: C
authors.lastname: Liu
authors.affiliation: School of Electronic Engineering, Bangor University, Bangor LL57 1UT, United Kingdom; State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Cai
authors.affiliation: State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China.
authors.forename: Baojian
authors.initials: B
authors.lastname: Xu
authors.affiliation: Department of Applied Science and Technology, Saint Peter's University, NJ 07306, USA.
authors.forename: Weidong
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Aston Institute of Photonic Technologies, Aston University, Birmingham B4 7ET, United Kingdom.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China. Electronic address: jlzhao@mail.sim.ac.cn.
authors.forename: Jianlong
authors.initials: J
authors.lastname: Zhao
authors.affiliation: School of Electronic Engineering, Bangor University, Bangor LL57 1UT, United Kingdom. Electronic address: x.chen@bangor.ac.uk.
authors.forename: Xianfeng
authors.initials: X
authors.lastname: Chen
mesh_terms: D000906:Antibodies / Q000276:immunology / Q000302:isolation & purification; D000888:Antibodies, Anti-Idiotypic / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D000941:Antigens / Q000276:immunology / Q000302:isolation & purification; D015374:Biosensing Techniques / Q000379:methods*; D006108:Graphite / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry
chemical_list: D000906:Antibodies; D000888:Antibodies, Anti-Idiotypic; D000941:Antigens; D010087:Oxides; C048844:anti-IgG; D006108:Graphite
keywords: Antibody-antigen; Biosensor; Graphene oxide; Immunosensor; Label-free; Long period grating