A long period grating-based platform for the detection of E. coli proteins

A Long Period Grating (LPG)-based platform for the detection of E. coli outer membranes proteins (EcOMPs) is presented. The sensing probe is achieved by the functionalization of a LPG inscribed in a single mode fiber (SMF28) with a DNA-aptamer resulting in a label-free configuration capable of specific recognize EcOMPs in waters. Measurement takes place by tracking the variations induced in the resonance wavelength by the refractive index changes at the fiber surface (≈100 nm/RIU). The sensing head was characterized and tested against EcOMPs and applied to spiked environmental water samples. The sensor displayed logarithmic responses in the range of 0.1 nM to 10 nM EcOMPs and is regenerated (under low pH conditions) and the deviation of the subsequent detection was less than 0.1 %.