Reflection-type long period grating biosensor for detection of drug resistant bacteria: the OptoBacteria project

In this paper, we report the experimental results on the fabrication and validation of a multilayer coated reflection-type long period fiber grating (LPG) biosensor, useful for the detection of antibiotic resistance bacteria. A standard LPG is first transformed in a practical probe working in reflection mode, then it is coated by two layers: atactic polystyrene (aPS) and (methyl methacrylate-co-methacrylic acid) (PMMA-co-MA). This multilayer strategy allow, at same time, to increase the surrounding refractive index sensitivity of the standard LPG and create the necessary conditions for a correct bio-functionalization. Standard linkage chemistry has been applied to anchor the bioreceptors on the probe surface. The experimental results demonstrate the capability of our LPG biosensor to successfully monitor all the biological steps of the biomolecular experiments, with β-lactamase AmpC binding detection tests obtained using two different ligands characterized by two different β-lactamase affinities.