Engineering a subcellular targetable, red-emitting, and ratiometric fluorescent probe for Ca2+ and its bioimaging applications.
A new, visible-light-excited and red-emitting fluorescent Ca(2+) probe, STDBT, was synthesized, which consists of 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid as a Ca(2+)-chelating moiety and two benzothiazolium hemicyanine dyes as fluorophores. The spectral profiles of its free and Ca(2+)-bound forms were studied. Upon addition of Ca(2+), the fluorescence spectra of STDBT displayed a significant enhancement (about 48-fold) in fluorescence intensity and a 20-nm blueshift (from 600 to 580 nm) in the emission spectrum. Both the absorption and the excitation spectra of STDBT showed a very large (more than 100 nm) hypsochromic shift in the long-wavelength maxima upon binding with Ca(2+). Interestingly, in contrast with the commonly used Ca(2+) indicator Fluo-3, when the acetoxymethyl ester of STDBT enters into cells, it distributes both in the cytosol and the nucleus, but displays a very clear boundary between the two compartments. This allows STDBT to be used as a double targetable Ca(2+) probe that can be used to report cytoplasmic Ca(2+) and nuclear Ca(2+) simultaneously.
Zhu
Baocun
B
Department of Chemistry, School of Science, Beijing Institute of Technology, Beijing 100081, China.
Jia
Hongying
H
Zhang
Xiaoling
X
Chen
Yan
Y
Liu
Haipeng
H
Tan
Weihong
W
D052160:Benzothiazoles / Q000737:chemistry; D002118:Calcium / Q000032:analysis* / Q000378:metabolism; D002413:Cations, Divalent / Q000032:analysis / Q000378:metabolism; D002460:Cell Line; D002466:Cell Nucleolus / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D006801:Humans; D018613:Microscopy, Confocal / Q000379:methods*
D052160:Benzothiazoles; D002413:Cations, Divalent; D005456:Fluorescent Dyes; D004533:Egtazic Acid; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium