title: Rational design of ratiometric near-infrared fluorescent pH probes with various pKa values, based on aminocyanine.
abstract: Novel ratiometric, near-infrared fluorescent pH probes with various pK(a) values have been designed and synthesized on the basis of aminocyanine bearing a diamine moiety, and their photochemical properties were evaluated. Under acidic conditions, these pH probes showed a 46- to 83-nm red shift of the absorption maximum. This change is sufficiently large to permit their use as ratiometric pH probes, and is reversible, whereas monoamine-substituted aminocyanines showed irreversible changes because of their instability under acidic conditions. Furthermore, the pK(a) values of these probes can be predicted from the calculated pK(a) values of the diamine moieties, obtained from the SciFinder database. This design strategy is very simple and flexible, and should be applicable to develop NIR pH probes for various applications.
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Myochin
authors.forename: Kazuki
authors.initials: K
authors.lastname: Kiyose
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Hanaoka
authors.forename: Hirotatsu
authors.initials: H
authors.lastname: Kojima
authors.forename: Takuya
authors.initials: T
authors.lastname: Terai
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Nagano
mesh_terms: D003959:Diamines / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D003959:Diamines; D005456:Fluorescent Dyes