Photonic crystals on copolymer film for bacteria detection.

The development of two-dimensional photonic crystals (PCs) on a copolymer film is described in connection with Fresnel reflection spectroscopy and fluorescence microscopy. Label-free detection of Legionella pneumophila was performed using a PC platform with a detection limit of 200 cells/mL. L. pneumophila is well known as the cause of Legionnaires' disease and a lesser form called Pontiac fever. Since death by L. pneumophila infection depends on the early anti-microbial treatment, rapid diagnosis of this disease is critical for efficient treatment and patient survival. Conventional assays have turn-around times measurable in several hours to days, and are limited in their detection of various serogroups. Due to the recent introduction of regulatory guidelines for routine testing of water cooling towers and treatment facilities, biosensors for the on-field detection of Legionella spp. are highly in demand. The versatile and economical immunochips described here can be easily adapted for the monitoring of L. pneumophila serogroups in clinical and environmental samples in a few minutes.