title: Highly sensitive optical fibre long period grating biosensor anchored with silica core gold shell nanoparticles.
abstract: An optical fibre long period grating (LPG), modified with a coating of silica core gold shell (SiO2:Au) nanoparticles (NPs) deposited using the layer-by-layer method, was employed for the development of a biosensor. The SiO2:Au NPs were electrostatically assembled onto the LPG with the aid of a poly(allylamine hydrochloride) (PAH) polycation layer. The LPG sensor operates at the phase matching turning point to provide the highest sensitivity. The SiO2:Au NPs were modified with biotin, which was used as a ligand for streptavidin (SV) detection. The sensing mechanism is based on the measurement of the refractive index change induced by the binding of the SV to the biotin. The effect on sensitivity of increasing the surface area by virtue of the SiO2:Au nanoparticles' diameter and film thickness was studied. The lowest measured concentration of SV was 2.5nM, achieved using an LPG modified with a 3 layer (PAH/SiO2:Au) thin film composed of SiO2 NPs of 300nm diameter with a binding constant of k=1.7(pM)(-1), sensitivity of 6.9nm/ng/mm(2) and limit of detection of 19pg/mm(2).
authors: Applied Optics Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK.
authors: L
authors: L
authors: Marques
authors: Applied Optics Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK.
authors: F U
authors: FU
authors: Hernandez
authors: Engineering Photonics, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK.
authors: S W
authors: SW
authors: James
authors: Applied Optics Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK.
authors: S P
authors: SP
authors: Morgan
authors: Applied Optics Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK.
authors: M
authors: M
authors: Clark
authors: Engineering Photonics, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK.
authors: R P
authors: RP
authors: Tatam
authors: Applied Optics Group, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK; Engineering Photonics, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK. Electronic address: s.korposh@nottingham.ac.uk.
authors: S
authors: S
authors: Korposh
mesh_terms: D015374:Biosensing Techniques; D001710:Biotin / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D055100:Optical Fibers; D011073:Polyamines / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D019809:Streptavidin / Q000737:chemistry
chemical_list: D011073:Polyamines; C063994:polyallylamine; D001710:Biotin; D006046:Gold; D012822:Silicon Dioxide; D019809:Streptavidin
keywords: Antigen–antibody; Biosensor; Layer-by-layer; Long period grating; Silica-gold core/shell nanoparticles