An optical fibre long period grating (LPG), modified with a coating of silica gold (SiO₂:Au) core/shell nanoparticles (NPs) deposited using the layer-by-layer (LbL) method, was employed for the development of a bio-sensor. The SiO₂:Au NPs were electrostatically assembled onto the LPG with the aid of a poly(hydrochloride ammonium) (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 lowest detected concentration of SV was 19 nM using an LPG modified with a 3 layer (PAH/SiO₂:Au) thin film.

Date Published: 2 June 2014
PDF: 4 pages
Proc. SPIE 9157, 23rd International Conference on Optical Fibre Sensors, 91574S (2 June 2014); doi: 10.1117/12.2059196

Published in SPIE Proceedings Vol. 9157:
23rd International Conference on Optical Fibre Sensors
José M. López-Higuera; Julian D. C. Jones; Manuel López-Amo; José Luis Santos, Editor(s)