Near-Infrared-Emitting Squaraine Dyes with High 2PA Cross-Sections for Multiphoton Fluorescence Imaging

    Authors

    H. Y. Ahn; S. Yao; X. Wang;K. D. Belfield

    Comments

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    Abbreviated Journal Title

    ACS Appl. Mater. Interfaces

    Keywords

    near infrared (NIR) dyes; squaraine; linear and nonlinear optical; properties; bioimaging; two-photon fluorescence microscopy; ABSORBING FLUORENE DERIVATIVES; OPTICAL-DATA STORAGE; ONE-PHOTON; 2-PHOTON ABSORPTION; PHOTODYNAMIC THERAPY; CYANINE DYES; SOLAR-CELLS; PHOTOSTABILITY; EFFICIENCY; AGGREGATION; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary

    Abstract

    Designed to achieve high two-photon absorptivity, new near-infrared (NIR) emitting squaraine dyes, (E)-2-(1-(2-(2-methoxyethoxy)ethyl)-5-(3,4,5-trimethoxystyryl)-1H-pyrrol-2-yl)-4-(1-(2-(2-methoxyethoxy)ethyl)-5-(3,4,5-trimethoxystyryl)-2H-pyrrolium-2-ylidene)-3-oxocyclobut-1-enolate (1) and (Z)-2-(4-(dibutylamino)-2-hydroxyphenyl)-4-(4-(dibutyliminio)-2-hydroxycyclohexa-2,5-dienylidene)-3-oxocyclobut-1-enolate (2), were synthesized and characterized. Their linear photophysical properties were investigated via UV-visible absorption spectroscopy and fluorescence spectroscopy in various solvents, while their nonlinear photophysical properties were investigated using a combination of two-photon induced fluorescence and open aperture z-scan methods. Squaraine 1 exhibited a high two-photon absorption (2PA) cross-section (delta(2PA)), similar to 20 000 GM at 800 nm, and high photostability with the photochemical decomposition quantum yield one order of magnitude lower than Cy 5, a commercially available pentamethine cyanine NIR dye. The cytotoxicity of the squaraine dyes were evaluated in HCT 116 and COS 7 cell lines to assess the potential of these probes for biomedical imaging. The viability of both cell lines was maintained above 80% at dye concentrations up to 30 mu M, indicating good biocompatibility of the probes. Finally, one-photon fluorescence microscopy (1PFM) and two-photon fluorescence microscopy (2PFM) imaging was accomplished after incubation of micelle-encapsulated squaraine probes with HCT 116 and COS 7 cells, demonstrating their potential in 2PFM bioimaging.

    Journal Title

    Acs Applied Materials & Interfaces

    Volume

    4

    Issue/Number

    6

    Publication Date

    1-1-2012

    Document Type

    Article

    Language

    English

    First Page

    2847

    Last Page

    2854

    WOS Identifier

    WOS:000305716900004

    ISSN

    1944-8244

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