title: Sulfone-Rhodamines: A New Class of Near-Infrared Fluorescent Dyes for Bioimaging.
abstract: Given the wavelength dependence of tissue transparency and the requirement for sufficiently low background autofluorescence, the development of fluorescent dyes with excitation and emission maxima beyond 700 nm is highly desired, but it is a challenging task. Herein, a new class of fluorescent dyes, named sulfone-rhodamines (SO2Rs), was developed on the basis of the one-atom replacement of the rhodamine 10-position O atom by a sulfone group. Such a modification makes their absorption and emission maxima surprisingly reach up to 700-710 and 728-752 nm, respectively, much longer than their O-, C-, and Si-rhodamine analogs, due to the unusual d*-π* conjugation. Among these dyes, SO2R4 and SO2R5, bearing disubstituted meso-phenyl groups, show the greatest potentials for bioimaging applications in view of their wide pH range of application, high photostability, and big extinction coefficients and fluorescence quantum yields. They could quickly penetrate cells to give stable NIR fluorescence, even after continuous irradiation by a semiconductor laser, making them suitable candidates for time-lapse and long-term bioimaging applications. Moreover, they could specifically localize in lysosomes independent of alkylmorpholine targeted group, thus avoiding the problematic alkalization effect suffered by most LysoTrackers. Further imaging assays of frozen slices of rat kidney reveal that their tissue imaging depth is suprior to the widely used NIR labeling agent Cy5.5.
authors.affiliation: School of Chemistry and Chemical Engineering and ‡Institute of Biotechnology, Shanxi University , Taiyuan 030006, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: School of Chemistry and Chemical Engineering and ‡Institute of Biotechnology, Shanxi University , Taiyuan 030006, China.
authors.forename: Yuan-Qiang
authors.initials: YQ
authors.lastname: Sun
authors.affiliation: School of Chemistry and Chemical Engineering and ‡Institute of Biotechnology, Shanxi University , Taiyuan 030006, China.
authors.forename: Hongxing
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Chemistry and Chemical Engineering and ‡Institute of Biotechnology, Shanxi University , Taiyuan 030006, China.
authors.forename: Heping
authors.initials: H
authors.lastname: Shi
authors.affiliation: School of Chemistry and Chemical Engineering and ‡Institute of Biotechnology, Shanxi University , Taiyuan 030006, China.
authors.forename: Yawei
authors.initials: Y
authors.lastname: Shi
authors.affiliation: School of Chemistry and Chemical Engineering and ‡Institute of Biotechnology, Shanxi University , Taiyuan 030006, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Guo
mesh_terms: D005453:Fluorescence; D005456:Fluorescent Dyes; D008247:Lysosomes; D012235:Rhodamines / Q000737:chemistry*; D013450:Sulfones
chemical_list: D005456:Fluorescent Dyes; D012235:Rhodamines; D013450:Sulfones
keywords: fluorescent dyes; imaging agents; near-infrared; rhodamines; sulfones