Biosensing based upon molecular confinement in metallic nanocavity arrays

Research world-wide on biosensing techniques is motivated by numerous applications in clinical diagnostics, genetic screenings, proteomics, and single-molecule detection, for example. However, the important problem of detecting in parallel a large number of molecular species from very small samples remains an elusive goal. This work represents a step in that direction through the development of a biosensor platform in which enhanced fluorescence transduction occurs through the optical excitation of molecules located within metallic nanocavities. This study also demonstrates that the phenomenon of enhanced transmission can be used as a technique for molecular transduction in optical biosensor applications with the important benefits of an apparent increase in fluorescence yield and isolation from fluorescence produced by unbound species. Finally, we demonstrate that real-time biosensing can be performed by monitoring the fluorescence signal produced due to the hybridization between probe oligonucleotide's immobilized within the nanocavities and complementary target oligonucleotides in solution introduced through a microfluidic channel.