Hybrid One-Dimensional Plasmonic-Photonic Crystals for Optical Detection of Bacterial Contaminants.

Photonic crystal-based biosensors hold great promise as low-cost devices for real-time monitoring of a variety of biotargets, for example, bacterial contaminants in food. Here, we report the proof-of-concept for a new colorimetric sensor of bacterial contamination, which is based on a novel hybrid plasmonic-photonic device. Our system consists of a layer of silver, a plasmonic metal exhibiting a well-known bioactivity, on top of a one-dimensional photonic crystal. We attribute the bioresponsivity to the formation of polarization charges at the Ag/bacterium interface within a sort of "bio-doping" mechanism. Interestingly, this triggers a blue shift in the photonic response. As an example, we assessed the validity of our approach by detecting one of the most hazardous contaminants, . This work demonstrates that our device can be a low-cost and portable platform for the detection of common bacterial contaminants.