Localization of Plasmon Field in Nanospace and Application to Fluorescence Analysis

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Localization of surface plasmon filed based on light-wavelength sized apertures on gold surface has been studied. The 500 nm and 600 nm apertures were prepared by projection method using polystyrene latex beads. ATR illumination of the gold films having the apertures resulted in extraordinary light transmission at the specific wavelengths corresponding to the aperture sizes. Fluorescence immunoassay in the apertures has been carried out by immobilization of anti-IgG on the bottom glass surface of the aperture. Upon putting a droplet of a PBS solution of IgG Texas Red conjugate during ATR illumination of the 20 apertures by 532 nm light induced remarkable increase in the fluorescence signal. The control experiment using BSA Texas Red conjugate gave no fluorescence signal, on the other hand. The fluorescence DNA assay in the apertures using 15mer oligonucleotides was also successful. The present results demonstrated fluorescence analyses in the nanospace based on plasmon enhanced excitation and development of the protein and DNA nanoarrays based on this novel localization method of photons in nanospace is expected.