Long period grating-based fiber optic sensor for label-free DNA detection

The feasibility of a DNA biosensor based on a long period grating inscribed in an optical fiber has been investigated. The sensor can perform a label-free detection, due to the functionalization of the optical fiber external surface with peptide nucleic acid probes matched with the DNA target strands. A wavelength shift of 1.2 nm for a 120 nM DNA solution has been measured. Fluorescence measurements have been also taken, in order to give a further proof of the fiber functionalization and hybridization.