Graphene oxide-functionalized long period fiber grating for ultrafast label-free glucose biosensor

A label-free glucose biosensor is constructed successfully based on the long period fiber grating (LPFG) functionalized with graphene oxide (GO)-glucose oxidase (GOD) via the chemical crosslink method. GO coated on the surface of LPFG can immobilize GOD by the plentiful binding sites because of its favorable combination of exceptionally high surface-to-volume ratio. The structure and characterization of GOD-GO-modified LPFG are studied by the optical microscope, Fourier transformation infrared spectrometer (FTIR), Raman spectroscopy, scanning electron microscope (SEM) and atomic force microscopy (AFM), respectively. The reaction between GOD and glucose create gluconic acid and H₂O₂, which will lead to an evident shift of LPFG transmission spectrum due to the greater change of the surrounding refractive index (SRI). The GOD-GO-modified LPFG sensor shows a linear response with a response coefficient of 0.77 nm/(mg/mL). This biosensor has good selectivity and can be used for the detection of practical sample. The GOD-GO-modified LPFG biosensor has great prospect in the pharmaceutical research and medical diagnosis fields.