Organic Letters
Letter
ASSOCIATED CONTENT
Supporting Information
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Experimental procedures, biological experiments, and
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H, C, and 2D NMR spectra for all new compounds
AUTHOR INFORMATION
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ORCID
Notes
Figure 4. (A) Fluorescence lifetime and (B) fluorescence images
obtained for HeLa cells incubated with 5d (5 μM). (C) Fluorescence
lifetime and (D) fluorescence images obtained for HeLa cells as a
control in the absence of 5d in HeLa cells. The fluorescence
intensities were obtained as relative values in (B) and (D).
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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This research was supported by the Basic Science Research
Program through the National Research Foundation of Korea
(NRF), funded by the Ministry of Education, Science and
Technology (grant no. 2019R1F1A1058712). We thank Dr.
Weon-Sik Chae for performing the fluorescence lifetime
measurements at the Korea Basic Science Institute (KBSI),
Daegu Center, Korea.
fluorescence lifetime of 5d in HeLa cells was comparable to the
viscosity of the endoplasmic reticulum (ER) reported in the
8c
literature (129.5 ± 7.2 cP), although the exact localization of
5d in the HeLa cells was not investigated using an ER-tracker
dye. In contrast, no sky-blue spot corresponding to the
fluorescence lifetime of 5d on the order of 0.6 ns was observed
in the HeLa cells in the absence of 5d, as shown in Figure 4C.
In addition, the strong fluorescent spots in Figure 4B were
overlapped with the sky-blue spots observed in the FLIM
image of Figure 4A. This indicated that the sky-blue spots
originate from 5d. In contrast, the strong fluorescence
intensities observed in Figure 4D were found in all parts of
the HeLa cells. Therefore, the strong fluorescence intensities
observed in Figure 4D represent the autofluorescence of the
cells. From these experiments, it was concluded that 5d can
enter the cell membrane and can be further developed as a new
category of viscosity sensor on a cellular level.
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cellular imaging applications, this disadvantage was overcome
using FLIM technology and the facile synthesis and simple
structure of 5d. The FLIM image of HeLa cells was obtained
upon treatment with 5 μM of 5d to map the viscosity of HeLa
cells and test the cell permeability. These studies prove that
tolan derivatives can be considered as a new category of
viscosity sensor and further modified toward various
applications.
D
Org. Lett. XXXX, XXX, XXX−XXX