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Fig. 4 Confocal fluorescence images of a polymeric fluorescent
sensor PNME at different temperatures in the HeLa cells: (a) 25 1C
and (b) 37 1C, respectively. The bar represents 10 mm.
4
5
LysoTracker Red showed convincing yellow fluorescence
(
Fig. 3(c)), which implied the colocalization of PNME in
lysosome. Meanwhile, the lysosome localization of PNME
demonstrated that PNME was taken up in lysosomes through
the endocytosis pathway and then accumulated in acidic
lysosomes (Fig. 3(c)). All these results indicated that PNME
could be used as an intracellular pH sensor for lysosome
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The intracellular temperature sensing of PNME was also
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with PNME at 25 1C displayed weak green fluorescence, while
the cells incubated with PNME at 37 1C exhibited brighter
green fluorescence, as shown in Fig. 4(b), which was also in
good agreement with in vitro results (Fig. 1(b)). The
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In summary, we have synthesized a novel water-soluble
polymeric fluorescent sensor PNME which responds to both
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exhibited a sensitive fluorescence change towards pH between
1
0 S. M. Borisov, R. Seifner and I. Klimant, Anal. Bioanal. Chem.,
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.0 and 10.0 at 25 1C, and showed strong fluorescence at pH o
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2
010, 33, 541; G. Mistlberger, K. Koren, S. M. Borisov and
as the temperature increased, and PNME could be used as a
thermometer to detect the temperature range from 32 to 40 1C
in aqueous solution. The subcellular localization of PNME
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be endocytosed by cells and accumulated in lysosomes, and
could be used as an intracellular pH sensor for lysosomes
imaging in living cells. Moreover, it also could sense different
temperature change in living cells at 25 and 37 1C, respectively.
The authors are grateful for the financial support from the
National Natural Science Foundation of China (21076077),
the National Science and Technology Pillar Program of China
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488 Chem. Commun., 2012, 48, 4486–4488
This journal is c The Royal Society of Chemistry 2012