Enhanced DNA Detection Through the Incorporation of Nanocones and Cavities Into a Plasmonic Grating Sensor Platform

In this paper, a novel plasmonic grating sensor platform was developed and tested for feasibility using a lights-ON fluorescence-based DNA assay. The sensor platform combined the fluorescence enhancement of a grating-based plasmonic platform with the electric field intensifying effects of nanoscale cones and cavities. The gratings were made through a microcontact printing process that replicated HD-DVD disks in polymethylsilsesquioxane and coated with a thin gold film. Nanocavities were incorporated into the sensor platform during the printing process and nanocones were incorporated during the 100-nm gold deposition process. Fluorescently tagged single-strand (ss) DNA molecules were immobilized onto the surface and were designed such that the molecules would fluoresce when bound to a complementary sequence. Sensor substrates were imaged after exposure to a mismatched and matched ssDNA to quantify the fluorescence enhancement of the sensor. Exposure to matched ssDNA resulted in fluorescent emission from the grating that was 13.6× brighter than flat gold, while the nanocones and nanocavities were 37.5× and 47.4× brighter than flat gold, respectively.