Ratiometric Fluorescence Azide-Alkyne Cycloaddition for Live Mammalian Cell Imaging.
Click chemistry with metabolic labeling has been widely used for selectively imaging biomacromolecules in cells. The first example of azide-alkyne cycloaddition for ratiometric fluorescent imaging of live cells is reported. The precursor of the azido fluorophore (cresyl violet) has a fluorescence emission peak at 620 nm. The electron-rich nitrogen of the azido group blue-shifts the emission peak to 566 nm. When the click reaction occurs, an emission peak appears at 620 nm due to the lower electronic density of the newly formed triazole ring, which allows us to ratiometrically record fluorescence signals. This emission shift was applied to ratiometric imaging of propargylcholine- and dibenzocyclooctyne-labeled human breast cancer cells MCF-7 under laser confocal microscopy. Two typical triazole compounds were isolated for photophysical parameter measurements. The emission spectra presented a fluorescence emission peak around 620 nm for both click products. The results further confirmed the emission wavelength change was the result of azide-alkyne cycloaddition reaction. Since nearly all biomolecules can be metabolically labeled by reported alkyne-functionalized derivatives of native metabolites, our method can be readily applied to image these biomacromolecules.
Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province and ‡Experimental Chemistry Teaching Center, School of Chemistry and Chemical Engineering, Shaanxi Normal University , 620 Xi Chang'an Street, Xi'an, Shaanxi 710119, People's Republic of China.
Hongxia
H
Fu
Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province and ‡Experimental Chemistry Teaching Center, School of Chemistry and Chemical Engineering, Shaanxi Normal University , 620 Xi Chang'an Street, Xi'an, Shaanxi 710119, People's Republic of China.
Yanru
Y
Li
Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province and ‡Experimental Chemistry Teaching Center, School of Chemistry and Chemical Engineering, Shaanxi Normal University , 620 Xi Chang'an Street, Xi'an, Shaanxi 710119, People's Republic of China.
Lingbo
L
Sun
Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province and ‡Experimental Chemistry Teaching Center, School of Chemistry and Chemical Engineering, Shaanxi Normal University , 620 Xi Chang'an Street, Xi'an, Shaanxi 710119, People's Republic of China.
Pan
P
He
Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province and ‡Experimental Chemistry Teaching Center, School of Chemistry and Chemical Engineering, Shaanxi Normal University , 620 Xi Chang'an Street, Xi'an, Shaanxi 710119, People's Republic of China.
Xinrui
X
Duan
D000480:Alkynes / Q000737:chemistry*; D001386:Azides / Q000737:chemistry*; D002470:Cell Survival; D061565:Cycloaddition Reaction; D005453:Fluorescence; D006801:Humans; D061986:MCF-7 Cells; D008856:Microscopy, Fluorescence; D057054:Molecular Imaging / Q000379:methods*; D015394:Molecular Structure
D000480:Alkynes; D001386:Azides