title: Beyond the diffraction-limit biological imaging by saturated excitation microscopy.
abstract: We demonstrate high-resolution fluorescence imaging in biological samples by saturated excitation (SAX) microscopy. In this technique, we saturate the population of fluorescence molecules at the excited state with high excitation intensity to induce strong nonlinear fluorescence responses in the center of laser focus, which contributes the improvement of the spatial resolution in three dimensions. Using SAX microscopy, we observed stained microtubules in HeLa cells with improved spatial resolution. We also measured the relation of the fluorescence and excitation intensity with several kinds of fluorescence dyes and, in the results, confirmed that SAX microscopy has the potential to observe any kind of fluorescence samples in current usage.
authors.affiliation: Osaka University, Department of Frontier Biosciences, 2-1 Yamadaoka, Suita, Osaka 565-871, Japan.
authors.forename: Masahito
authors.initials: M
authors.lastname: Yamanaka
authors.forename: Shogo
authors.initials: S
authors.lastname: Kawano
authors.forename: Katsumasa
authors.initials: K
authors.lastname: Fujita
authors.forename: Nicholas I
authors.initials: NI
authors.lastname: Smith
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kawata
mesh_terms: D006367:HeLa Cells; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008029:Lighting / Q000379:methods*; D018613:Microscopy, Confocal / Q000379:methods*; D008856:Microscopy, Fluorescence / Q000379:methods*; D008870:Microtubules / Q000648:ultrastructure*; D012031:Refractometry / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity