Highly sensitive plasmonic grating platform for the detection of a wide range of infectious diseases

We report the cost-effective fabrication of a plasmonic grating for improved light coupling in a fluorescence-based sensor platform by a simple micro-contact printing technique. The fluorescence of Rhodamine 6G (R6G) film on gratings was enhanced by up to 239-fold with respect to glass using a fluorescence microplate reader. The silver gratings are made suitable for use in biological buffers by a protective alumina layer. The platform has been optimized to detect Interferon-gamma (IFN_δ), a commonly used biomarker for M. tuberculosis infection and other autoimmune diseases, with an immunofluorescence assay. The platform demonstrates 500 fg/ml limit of detection (LOD) while commercial enzyme-linked immunosorbent assays (ELISA) report 2 pg/mL LOD. The extraordinary fluorescence enhancement was compared with simulation result to predict and support the experimental analysis. These results can be used to expand the platform for numerous fast, robust, sensitive biosensors.