Application of Grating Substrate Fabricated by Nanoimprint Lithography to Surface Plasmon Field-Enhanced Fluorescence Microscopy and Study of Its Optimum Structure

Nanoimprint lithography (NIL) has recently been expected to be applied in the field of nanobiology. Substrates with a subwavelength grating pattern covered with metal layers can provide grating-coupled surface plasmon resonance (GC-SPR) under suitable condition. The GC-SPR field can selectively excite a fluorescent dye bound to the substrate and its fluorescence can be enhanced. In our earlier work, using a glass substrate with a grating fabricated by photolithography and dry etching, fluorescence images of labeled cells were taken with high sensitivity under a fluorescence microscope. However, this fabrication process requires a great deal of time. The replication of the subwavelength grating pattern on a polymer film by thermal NIL has an advantage in fabrication process economy. In this study, a grating substrate fabricated by NIL was applied to fluorescence microscopic observation based on GC-SPR and it provided more than six-times enhanced fluorescence images. (C) 2009 The Japan Society of Applied Physics