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Molecular Design Strategies for Near‐Infrared Ratiometric Fluorescent Probes Based on the Unique Spectral Properties of Aminocyanines
Author(s) -
Kiyose Kazuki,
Aizawa Sakiko,
Sasaki Eita,
Kojima Hirotatsu,
Hanaoka Kenjiro,
Terai Takuya,
Urano Yasuteru,
Nagano Tetsuo
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200900035
Subject(s) - fluorescence , biomolecule , photochemistry , chemistry , absorption (acoustics) , förster resonance energy transfer , near infrared spectroscopy , fluorescence in the life sciences , fluorophore , materials science , optics , biochemistry , physics , composite material
In spite of the wide availability of various near‐infrared (NIR) fluorophores as labeling reagents, there are few functional NIR fluorescent probes for which change in the absorption and/or fluorescence spectra upon specific reaction with biomolecules is seen. The widely used photoinduced electron‐transfer mechanism is unsuitable for NIR fluorophores, such as tricarbocyanines, because their long excitation wavelength results in a small singlet excitation energy. We have reported the unique spectral properties of amine‐substituted tricarbocyanines, which were utilized to develop two design strategies. One approach was based on control of the absorption wavelength by using the difference in electron‐donating ability before and after a specific reaction with a biomolecule, and the other approach was based on control of the fluorescence intensity by modulating the Förster resonance energy‐transfer efficiency through a change in the overlap integral that arises from the change in absorption under acidic conditions. These strategies were validated by obtaining tricarbocyanine‐based ratiometric NIR fluorescent probes for esterase and for pH level.