title: Development of a far-red to near-infrared fluorescence probe for calcium ion and its application to multicolor neuronal imaging.
abstract: To improve optical imaging of Ca(2+) and to make available a distinct color window for multicolor imaging, we designed and synthesized CaSiR-1, a far-red to near-infrared fluorescence probe for Ca(2+), using Si-rhodamine (SiR) as the fluorophore and the well-known Ca(2+) chelator BAPTA. This wavelength region is advantageous, affording higher tissue penetration, lower background autofluorescence, and lower phototoxicity in comparison with the UV to visible range. CaSiR-1 has a high fluorescence off/on ratio of over 1000. We demonstrate its usefulness for multicolor fluorescence imaging of action potentials (visualized as increases in intracellular Ca(2+)) in brain slices loaded with sulforhodamine 101 (red color; specific for astrocytes) that were prepared from transgenic mice in which some neurons expressed green fluorescent protein.
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Egawa
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Hanaoka
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Koide
authors.forename: Sakiko
authors.initials: S
authors.lastname: Ujita
authors.forename: Naoya
authors.initials: N
authors.lastname: Takahashi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Ikegaya
authors.forename: Norio
authors.initials: N
authors.lastname: Matsuki
authors.forename: Takuya
authors.initials: T
authors.lastname: Terai
authors.forename: Tasuku
authors.initials: T
authors.lastname: Ueno
authors.forename: Toru
authors.initials: T
authors.lastname: Komatsu
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Nagano
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis*; D002413:Cations, Divalent / Q000032:analysis; D005456:Fluorescent Dyes / Q000737:chemistry*; D006624:Hippocampus / Q000737:chemistry* / Q000166:cytology; D051379:Mice; D009474:Neurons / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D002413:Cations, Divalent; D005456:Fluorescent Dyes; D012235:Rhodamines; D002118:Calcium