A fluorogenic probe for dynamic tracking of lipid droplets’ polarity during the evolution of cancer

Article abstract of DOI:10.1039/d0nj05900e

Exploring the changes in the polarity of intracellular lipid droplets (LDs) during the evolution of cancer is important for cancer detection and treatment. Therefore, we designed and synthesized a new type of polarity-sensitive fluorescent probe,CTPE, whi

Full text of DOI:10.1039/d0nj05900e

NJC
View Article Online
View Journal | View Issue
PAPER
A fluorogenic probe for dynamic tracking of lipid
droplets’ polarity during the evolution of cancer†
Cite this: New J. Chem., 2021,
a
a
a
ab
45, 4347
Cong Liu,
Junling Yin,
Bingli Lu
and Weiying Lin
*
Exploring the changes in the polarity of intracellular lipid droplets (LDs) during the evolution of cancer is
important for cancer detection and treatment. Therefore, we designed and synthesized a new type of
polarity-sensitive fluorescent probe, CTPE, which uses coumarin as the polarity-sensitive group and
tetraphenylethylene as the electron-donating group to target LDs. Due to its special intramolecular
charge transfer mechanism, CTPE emitted a weak green fluorescence in high-polar solvents, and a
strong green fluorescence in low-polar solvents, thus exhibiting a drastic change in fluorescence signal
as a function of the solvent polarity. In virtue of the probe CTPE, tumorous tissues have been
successfully identified from normal ones and the decrease in LDs’ polarity could be revealed with the
evolution of cancer. Moreover, the changes in the LDs’ polarity in drugs-treated tumor were observed at
the tissue level, endowing its capacity for anti-cancer drug efficacy evaluation. This work provides a
promising imaging tool for LDs tracking in cancer research and clinical diagnosis.
Received 3rd December 2020,
Accepted 26th January 2021
DOI: 10.1039/d0nj05900e
rsc.li/njc
Lipid droplets (LDs) are cellular organelles that store lipids
comprising a core of neutral lipids surrounded by a monolayer
Cancer is recognized as a severe disease with high mortality of phospholipids loaded with associated proteins. In addi-
rate, which is often a consequence of late diagnosis during tion to energy storage, LDs participate in physiological pro-
1
. Introduction
8
,9
1
,2
advanced stages. The timely diagnosis of cancer is critical cesses such as cell activation, migration, proliferation, and
1
0,11
such that effective treatment therapy can be initiated in early apoptosis.
Abnormal LDs can be detected in diseases such
stages without locally advancing the disease or metastasis. as type II diabetes, obesity, and atherosclerosis. Especially, due
Therefore, it is necessary to detect cancer in time to improve to specific alterations in the metabolic activity in cancer cells,
3
the survival rate. Accordingly, performing relevant research to parameters related to LDs should be quite different from
1
2–17
explore cancer evolution is highly desirable for current medical those of normal cells.
Recent evidence suggests that lipid
diagnostics. In recent years, cancer detection through related biosynthesis gets dysregulated because of the development of
markers has become a hot topic, which has been studied in cancer and reactivation of lipid biosynthesis is frequently
more and less economically developed countries alike. At observed in cancer tissue. The excess of LDs in a cancer cell
present, a large number of tumor markers have been discovered is attributed to the enhanced rate of glycolysis producing
1
8,19
through genomic and proteomic studies, which greatly facilitates pyruvate, known as the Warburg effect.
the diagnosis of cancer.
It should also be
4
–6
However, most of them fail to noted that the abnormal lipid content leads to the variation in
effectively detect cancer because of their invasive, unpleasant, hydrophilic and hydrophobic domains in the LD, further leading
7
and inconvenient nature. Therefore, it is particularly important to the change in the polarity of LDs. Although increasing
to develop a new strategy to identify tumors.
contribution has been devoted to the study of the metabolic
processes involved in LDs and their regulation within the context
of cancer, the potential role of LDs’ polarity in tumor progression
a
Institute of Fluorescent Probes for Biological Imaging, School of Chemistry and
20–23
have not yet been fully understood.
Thus, timely attention
Chemical Engineering, School of Materials Science and Engineering,
University of Jinan, Jinan, Shandong, 250022, People’s Republic of China.
E-mail: weiyinglin2013@163.com
should be given to the study of the LDs’ polarity during the
evolution of cancer.
b
Guangxi Key Laboratory of Electrochemical Energy Materials, Institute of Optical
Fluorescence imaging technology is a highly sensitive char-
acterization technique with the ability to perform non-
destructive, real-time and in situ detection of target analytes,
and has become a powerful tool for understanding biological
Materials and Chemical Biology, School of Chemistry and Chemical Engineering,
Guangxi University, Nanning, Guangxi, 530004, People’s Republic of China
†
Electronic supplementary information (ESI) available: Experimental details
including synthesis, the characterization of the compounds, absorption and
fluorescence spectroscopic data, and living cells imaging. See DOI: 10.1039/
d0nj05900e
2
4–27
systems with high spatial resolution.
Therefore, it can serve
as a feasible strategy to develop a new tool for studying the
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021
New J. Chem., 2021, 45, 4347À4353 | 4347

View Article Online
Paper
NJC
changes in the polarity of LDs in cancer development projects. 109.89, 108.69, 96.69, 45.20, 12.50. HR-MS m/z: calcd for
However, the predominated challenge in constructing such
optical agents is to control their luminescent behavior at
different polarities in systems. Ideally, the tumors should be
obviously discriminated from normal cells according to the
difference in their fluorescence signals caused by LDs’ polarity
variance. Another concern is to ensure that the probe is
primarily located in LDs to avoid false signals from other
suborganelles because the local polarity differs considerably
from one region to another. With polarity-sensitive and LDs
targeting optical agents, the contribution of LDs’ polarity in
tumor development could be revealed. However, to the best of
C
42
H
35NO
3
602.27; found, 602.2693.
2.3. General procedures for spectral test
The 1 mM CTPE stock solution was prepared in dimethyl
sulfoxide (DMSO). Toluene, dioxane, dichloromethane (DCM),
acetone, N,N-dimethylformamide (DMF) used in the experiment
were all spectrally pure. Before performing the spectrum test, the
solutions used were thoroughly shaken. All measurements were
performed using 420 nm excitation and 5.0 nm excitation/
emission gap width parameters.
our knowledge, such a powerful probe has not been proposed 2.4. Cell culture and imaging methods
for exploring the potential role of LDs polarity in the cancer
evolution.
In this work, we designed and synthesized a new fluorescent
The 4T1, HepG2, and HeLa cancer cells were used in this work.
Dulbecco’s Modified Eagle Medium media (DMEM, Hyclone)
supplemented with 10% heat-inactivated fetal bovine serum
probe CTPE with 3-acetyl-7-(N,N-diethyl)amino benzopyan-2-
one (the coumarin dye) as the polarity sensitive dye, with
tetraphenylethylene (TPE) as the electron donor. The probe
has excellent LDs targeting ability, good photo-stability and a
low biological toxicity. Owing to the intramolecular charge
transfer (ICT), CTPE exhibited a good solvation effect. As
anticipated, the probe displayed a stronger fluorescence in
cancerous tissues and a weaker fluorescence in the normal
tissues. Thus, cancer and normal tissues can be clearly
discriminated by fluorescence signals. Using this probe, the
LDs polarity in the evolution of cancer has been successfully
explored. In addition, LDs polarity fluctuations in cells incubated
with different stimulants have been detected.
À1
(
1
FBS, Sijiqing) and 1% antibiotics (100 U mL penicillin and
00 mg mL
À1
streptomycin, Hyclone) were utilized for cells
. Before imaging, 1 mL cells were
seeded in glass bottom culture dishes (Nest) at a density of
 10 mL . These cells were loaded on glass coverslips and
allowed to adhere for 24 h. After the cells were covered about
0% confluence, imaging experiments were carried out. For
culture at 37 1C and 5% CO
2
5
À1
1
7
imaging cells, 10 mL CTPE were mixed with 1 mL culture
medium firstly and then utilized for incubating cells for
30 min. Before imaging, cells were washed 3 times with PBS
to remove the residual probe. Finally, confocal fluorescence
imaging was carried out by Nikon fluorescence microscope
equipped with 100Â objective lens.
2
.5. Fluorescent imaging in tumor tissues and normal organs
2. Experimental
tissues
2
.1. Materials and instruments
Five-week-old female balb/c mice were purchased from the
School of Pharmaceutical Sciences, Shandong University, and
the studies were approved by the Animal Ethical Experiment
Committee of Shandong University. The entire experiment
followed the animal protection guidelines of the National
Laboratory Animal Use Law (China). 4T1 cells were transplanted
into mice to establish tumor models. These normal mouse
organs (heart, liver, spleen, lung, kidney) and tumor of tumor-
bearing mice were isolated, respectively, and wash them with
PBS (pH 7.4) thrice. With the help of a vibrating blade micro-
tome, the slices were cut to 200 mm thickness in 25 mM PBS
Unless otherwise stated, ultrapure water was utilized in the
experiments. Solvents were of spectral purity. All instruments
utilized in the research are illustrated in the ESI.†
2.2. Synthesis of CTPE
The synthetic route and part of the synthesis processes are
displayed in the ESI.† Compound 1 and compound 2 were
dissolved in 10 mL of solvent (ethanol) and three drops of
piperidine were added as a catalyst. Then, the mixture was
protected by nitrogen and refluxed at 80 1C for 24 h. After the
reaction was complete, the solution was cooled to room tem-
perature and the solvent in the reaction system was distilled off
under reduced pressure. The crude product was purified by
column chromatography (methanol : dichloromethane = 1 : 50),
(pH 7.4). Then, these slices were incubated with 15 mM CTPE in
PBS buffer for 2 h with 95% O and 5% CO at 37 1C. After
2
2
washing three times with PBS, these samples were transferred to
a glass bottom dish and observed under a confocal microscope.
1
and finally a red solid was obtained. H NMR (400 MHz,
chloroform-d) d 8.53 (s, 1H), 8.01 (d, J = 15.7 Hz, 1H), 7.74 (d,
J = 15.6 Hz, 1H), 7.44 (dd, J = 22.5, 8.3 Hz, 3H), 7.13–7.01 (m,
3
. Results and discussion
3.1. Design strategy of the probe CTPE
1
5H), 6.79 (d, J = 8.3 Hz, 1H), 6.63 (s, 1H), 5.30 (s, 1H), 3.47 (q,
1
3
J = 7.1 Hz, 4H), 1.26 (t, J = 7.0 Hz, 7H). C NMR (101 MHz, The donor (D)–p–acceptor (A) structure is generally beneficial
chloroform-d) d 186.43, 160.86, 158.68, 152.95, 148.63, 146.12, for polarity sensitivity and the hydrophobic nature is favorable
2
8
1
1
43.54, 143.44, 143.36, 143.10, 141.89, 140.37, 133.46, 128.20, for LDs targeting. Based on this, 3-acetyl-7-(N,N-diethyl)
27.86, 127.77, 127.66, 126.80, 126.62, 126.57, 124.52, 116.86, amino benzopyan-2-one (the coumarin dye) was selected as a
4348 | New J. Chem., 2021, 45, 4347À4353
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021

View Article Online
NJC
Paper
Fig. 1 The design concept of the probe CTPE for monitoring LDs polarity in cancer cells and normal cells.
fluorophore because it shows substantial changes in the dipole may change, and this change will be manifested by the fluorescence
moments while undergoing electronic transitions, and therefore intensity of the tissue incubated with CTPE (Fig. 1).
2
9
can serve as polarity-sensitive dye. Tetraphenylethylene (TPE)
plays the role of electron donor in CTPE probe, and the intro-
3.2. Optical properties of CTPE
duction of TPE increases the conjugation in CTPE as evidenced The absorption and fluorescence spectra of CTPE in solvents
by red shift, which makes it more suitable for biological such as toluene, dioxane, dichloromethane (DCM), acetone,
30
imaging. According to our assumption, the fluorescence intensity and N,N-dimethylformamide (DMF) were analyzed. As show in
of the probe with this push–pull electronic structure will be Fig. 2a, the absorption wavelength of CTPE in solvents of
3
1,32
sensitive to polarity.
We anticipated that owing to the LDs different polarities were slightly red shifted from 456 nm of
polarity variance caused by specific alterations in metabolism toluene to 464 nm of DMF. In the fluorescence spectra, this
of cancer, the probe will exhibit stronger fluorescence in cancer trend is even more obvious. As shown in Fig. 2b, the emission
tissues and weaker in normal tissues. Moreover, with the wavelength of CTPE ranges from 502 nm in low-polarity solvent
development of the tumor, the LDs polarity of the tumor tissue (toluene) to 561 nm in the highly polar solvent (DMF) with a red
Fig. 2 (a) The absorption spectra of CTPE in solvents with various polarities. (b) The fluorescence spectra of CTPE in solvents with various polarities.
(
c) The plot of the emission maximum of the probe CTPE in diverse solvents versus E
T
(30). (d) Fluorescence spectra of CTPE in different ratios of
methanol and glycerol system. Concentration: 10 mM; lex = 460 nm.
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021
New J. Chem., 2021, 45, 4347À4353 | 4349

View Article Online
Paper
NJC
shift of 59 nm. Simultaneously, as shown in Fig. 2b, as the cytotoxicity test of the probe in HepG2, HeLa and 4T1 cells
polarity of the solvent increases, the fluorescence intensity of (Fig. S6, ESI†). The results show that even when the probe
CTPE decreases accordingly, which may be ascribed to the concentration is 50 mM, the survival rate could still reach over
3
3
‘
‘positive solvatokinetic effect’’. This effect can be manifested 80%. The above results show that the probe CTPE has high
by changes in the fluorescence quantum yield of CTPE in selectivity, low biological toxicity and a good photo-stability,
different solvents (Table S1, ESI†). Moreover, the fluorescent therefore making it an excellent tool for detecting polarity in
lifetime variation of the CTPE under different polarities was complex biological systems.
studied. From Fig. S1 (ESI†), it can be seen that as the solvent
3
.3. Co-localization experiments
polarity increases, the fluorescent lifetime of the probe in
different solvents gets shortened. To further understand the
influence of solvent polarity on CTPE emission, a linear regression
curve of the maximum emission wavelength of the probe with
Subsequently, the commercial dye Nile red and CTPE were used
for colocalization experiments. An ideal condition was explored
first to ensure that green fluorescence only came from the
probe CTPE (Fig. 3a), and red fluorescence (Fig. 3b) only came
from Nile red. HepG2, HeLa, 4T1 cells were co-cultured with
CTPE and Nile red at the same time. As shown in Fig. 3c,
we observed granular dots in both red and green channels,
which is a typical shape for LDs (Fig. 3c). Moreover, yellow
fluorescence was observed in the merge image, indicating that
the two channels have a large overlap, and the correlation of the
intensity scatter plot reached 0.92. All these results indicate
that the probe has the property of locating LDs in cells, and
CTPE is capable of monitoring the changes in polarity of LDs in
living cells.
respect to the solvent polarity parameter E (30) was plotted. As
T
2
displayed in Fig. 2c, an excellent linearity (R = 0.982) was
obtained when the emission maximum of CTPE was plotted
against the E (30). This data indicated that the probe is highly
T
dependent on polarity, which is consistent with our original probe
design philosophy.
Due to the existence of single bonds in the CTPE structure,
limiting the rotation of single bonds by increasing the solvent
viscosity is expected to affect the fluorescence of the probe to a
certain extent. To understand the influence of viscosity on the
fluorescence intensity, the fluorescence spectra of CTPE in the
methanol–glycerol system with different ratios were measured.
As shown in Fig. 2d, with the increase of solvent viscosity, the 3.4. Imaging LDs polarity under abnormal physiological state
maximum fluorescence intensity of CTPE only increased from
The polarity of LDs in cells under abnormal physiological
219.8 to 579.8, while the maximum fluorescence intensity of
conditions was further monitored by confocal microscopy. As
shown in Fig. 4a, the cells were incubated with CTPE for 1 hour.
Granular LDs were seen in the cells and appropriate fluorescence
intensity was observed. Previous reports have shown that when
fatty acids (such as oleic acid) are added to the cell culture
each solvent in Fig. 2b is mostly higher than this change. To
further prove that CTPE is more sensitive to polarity, we
compared the fluorescence spectra of CTPE in THF and MeOH
solvent mixture (Fig. S2, ESI†), which have similar viscosities
but different polarities. The fluorescence spectrum of CTPE in
this system significantly changed. The above results show that
the sensitivity of CTPE probe to polarity is much higher than
that of viscosity of the solution. In other words, the change in
the probe fluorescence intensity with viscosity is basically
negligible. Therefore, we believe that CTPE could be utilized
to detect the polarity change despite being in viscous media.
Living biological cells are a very complex system that contains
a variety of biological macromolecules and a variety of ions.
To detect the selectivity of probe polarity in such a complex
environment, the fluorescence spectra of the probe CTPE in the
presence of Gln, Thr, Cys, Gly, Asn and other biological
macromolecules, and various ions were collected. As shown
in Fig. S3 (ESI†), the fluorescence of the probe did not change
significantly indicating that the probe was not influenced by
these biomolecules and ions. In addition, the result of probe in
different pH solutions demonstrated that CTPE is essentially
pH-insensitive over the pH range of 3.0–10.0 (Fig. S4, ESI†).
These results indicate that CTPE has high selectivity and can
detect changes in polarity in more complex environments. In
the photo stability experiment (Fig. S5, ESI†), it can be seen that
the fluorescence intensity of CTPE hardly changes with time
even under continuous irradiation of 90 min, which proves its
excellent photo-stability. Furthermore, to verify the biological
toxicity of CTPE, the MTT assay was introduced to establish the
medium, the number and size of LDs changes due to the
34,35
stimulation of the fatty acid receptor FFAR4.
Herein, 10 mL
Fig. 3 The co-localization fluorescence images of CTPE in 4T1 cells.
(
a) CTPE (1 mM) stain. (b) Nile red (2.0 mM) stain. (c) Merged image of
a) and (b). (d) The intensity scatter plot of two channels. Scale bar: 20 mm.
(
Green channel: lex = 488 nm, collected 500–550 nm. Red channel:
ex = 561 nm, collected 570–620 nm.
l
4350 | New J. Chem., 2021, 45, 4347À4353
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021

View Article Online
NJC
Paper
Similarly, weak florescence was also observed in taxol (Fig. 4d)
and sucrose (Fig. 4e) treated group. The results demonstrated
that the LDs’ polarity will decrease in abnormal cell state.
Moreover, similar phenomena were obtained in HeLa and
HepG2 cells (Fig. S7 and S8, ESI†). Thus, we believe that CTPE
can dynamically monitor the LDs’ polarity in cells under
different conditions.
3.5. Fluorescence imaging of LDs polarity in the evolution of
cancer
Based on the above detection results for abnormal cells, we
tried to further explore the changes in the polarity of LDs
during the evolution of cancer in the tissues. Four different
mouse tumor models were established (Fig. S9, ESI†). 4T1 cells
were inoculated into normal mice to establish a tumor model,
and the tumor tissues were obtained after 2 days, 5 days and
1
8
0 days, respectively. Concurrently, 20 mL taxol was injected to
day-tumor mice as a treatment group and the proposed slices
were obtained after 2 days of treatment (Fig. 5). The above
tissues were sliced in PBS. After CTPE staining, granular bright
spots could be seen in the tumor tissue, which is a typical shape
of LDs, indicating that CTPE could still locate LDs in the tissue.
As expected, the polarity of LDs in tumor tissue changed
with the time of inoculation, and this change is reflected by the
fluorescence brightness after CTPE staining. This indicates that
as the tumor develops, the number of LDs gradually decreased.
Note that, after drug treatment, the fluorescence intensity of
tumor decreased significantly compared with the 10 day-tumor
slices, indicating that the LDs polarity increased. The above
results revealed that with the evolution of cancer, the polarity
of LDs in tumor tissue gradually decreases, and after the
Fig. 4 Fluorescence imaging of 4T1 cells. (a1–a3) 4T1 cells incubated with treatment, the polarity in tumor tissue increases again.
1
0 mM probe CTPE for 30 min; (b1–b3) 4T1 cells incubated with 20 mM
In addition, the penetration ability of the probe in different
organ tissues (heart, liver, spleen, lung, kidney) was examined,
and the fluorescence could still be observed at a depth of 50 mm
oleic acid for 1 h and 10 mM CTPE for another 30 min (c1–c3) 4T1 cells
were incubated with PBS for 24 hours and 10 mM CTPE for another 30 min;
(
d1–d3) 4T1 cells incubated with 20 mM taxol for 30 min and 10 mM CTPE
for another 30 min. (e1–e3) 4T1 cells incubated with 20 mM sucrose
solution for 30 min and 10 mM CTPE for another 30 min. Conditions:
l
em = 500–550 nm; lex = 488 nm. Scale bar: 20 mm.
of oleic acid was added to the medium and then incubated with
probe for 1 hour and imaged. Simultaneously, the cells that were
only incubated with the probe were set as control group.
Compared with the control group (a1–a3), the number and
volume of LDs increased, hence, the fluorescence intensity of
LDs increased after incubation with oleic acid (Fig. 4b). The
results show that besides polarity CTPE can also dynamically
monitor the number and size of LDs in living cells.
In addition, detecting the polarity changes in LDs of cells in
different states is necessary to understand the pathological
process of LDs-related diseases. Therefore, three models of
abnormal cell state were established to detect changes in
LDs’ polarity. In detail, PBS (pH = 7.4) was utilized to culture
4
T1 cells instead of another medium to produce starvation. As
Fig. 5 The imaging of mouse tumors slices of different periods and
drug-treated tumors slices with CTPE (10 mM) at a depth of 10–50 mm.
shown in Fig. 4c, in the state of starvation, the probe exhibited
weaker fluorescence compared with control group (Fig. 4a). The fluorescence was collected at 500–550 nm with 488 nm excitation.
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021
New J. Chem., 2021, 45, 4347À4353 | 4351

View Article Online
Paper
NJC
than the other. This indicates that the polarity of LDs in
inflamed tissues is lower than that in normal tissues; with the
occurrence of inflammation, the number of LDs also increased.
Finally, to ensure that the fluorescence in tissue imaging is
entirely from CTPE, we used confocal microscopy to image the
tissue without CTPE staining under the same parameters, and
only negligible fluorescence was found in the imaging results
(Fig. S10, ESI†).
4. Conclusion
In summary, we designed and synthesized a new polar fluor-
escent probe CTPE targeting LDs and explored the LD polarity
of cancer tissues at different stages. In addition to their targeting
ability, CTPE also exhibited a good biocompatibility and photo
stability. Due to the donor–p–acceptor structure of CTPE, the
probe displayed a high sensitivity towards the polarity of the
environment, endowing CTPE the ability to specifically detect
the polarity of LDs in living cells. By means of the probe, the LDs’
polarity in cells as induced by PBS, sucrose and taxol was
successfully sensed. More importantly, in virtue of the CTPE,
the change trend of the polarity of LDs during the evolution of
cancer was explored, and the therapeutic effects of paclitaxel
were also tracked. We believe that CTPE has the potential to
become a powerful tool for exploring pathological changes in the
development of cancer.
Fig. 6 The imaging the subcutaneous tissue sections of inflammatory
mice and normal mice pretreated with CTPE (10 mM) with a depth of 10–50 mm.
Fluorescence was collected at 500–550 nm under excitation at 488 nm.
confirming a good penetration depth of CTPE (Fig. 6). In a
nutshell, this work demonstrated that the probe can be used as
a powerful tool for cancer diagnosis and for tracking therapeutic
efficacy by detecting LDs polarity.
Conflicts of interest
3
.6. Fluorescence imaging of LDs polarity in the
There are no conflicts to declare.
inflammation mice
In addition, the inflammatory mouse model was established to
explore the change of the polarity of LDs. Through intraperitoneal Acknowledgements
injection of 20 mL lipopolysaccharide (LPS), a mouse model
This work was financially supported by NSFC (21672083,
1877048, 22077048), Taishan Scholar Foundation
of acute inflammation was obtained after 24 h, and a
subcutaneous tissue section of the abdominal cavity was taken.
After adding CTPE staining for 2 h, imaging was performed
using a confocal microscope, and granular LDs could be seen in
the imaging results (Fig. 7). By comparing with the subcutaneous
tissue of normal mice, it could be seen that the fluorescence in
the inflamed tissue was stronger than that in the normal tissue
and the number of LDs in the inflammation model was higher
2
(
(
TS201511041), and the startup fund of the University of Jinan
309-10004).
Notes and references
1
2
3
R. L. Siegel, K. D. Miller and A. Jemal, Ca-Cancer J. Clin.,
016, 66, 7.
T. E. Byers, H. J. Wolf and K. R. Bauer, et al., Cancer, 2010,
13(3), 582–591.
R. D. Neal, P. Tharmanathan and B. France, et al., Br.
J. Cancer, 2015, 112, S92–S107.
2
1
4
5
P. C. Boutros, Genome Res., 2015, 25(10), 1508–1513.
M. Chiba, Y. Ichikawa, M. Kamiya, T. Komatsu, T. Ueno,
K. Hanaoka, T. Nagano, N. Lange and Y. Urano, Angew.
Chem., Int. Ed., 2017, 56, 10418–10422.
6
7
M. Gao, F. Yu, C. Lv, J. Choo and L. Chen, Chem. Soc. Rev.,
2017, 46, 2237–2271.
Fig. 7 The imaging the subcutaneous tissue sections of inflammatory
mice and normal mice pretreated with CTPE (10 mM) with a depth of 10–50
mm. Fluorescence was collected at 500–550 nm under excitation at
B. Daniele, A. Bencivenga, A. S. Megna and V. Tinessa,
Gastroenterology, 2004, 127, S108.
4
88 nm.
8 R. V. Farese and T. C. Walther, Cell, 2009, 139, 855–860.
4352 | New J. Chem., 2021, 45, 4347À4353
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021

View Article Online
NJC
Paper
9
S. Martin and R. G. Parton, Nat. Rev. Mol. Cell Biol., 2006, 7, 22 C. Ghosh, S. Nandi and K. Bhattacharyya, Chem. Phys. Lett.,
73–378. 2017, 670, 27–31.
0 T. C. Walther and R. V. Farese, Jr., Annu. Rev. Biochem., 2012, 23 R. Chowdhury, M. A. Amin and K. Bhattacharyya, J. Phys.
1, 687–714. Chem. B, 2015, 119, 10868–10875.
1 H. S. Finstad, C. A. Drevon and M. A. Kulseth, et al., 24 H. Abramczyk, J. Surmacki, M. Kopec, A. K. Olejnik,
3
1
1
1
1
1
1
1
8
Biochem. J., 1998, 336(2), 451–459.
2 S. O. Olofsson, P. Bostrom, L. Andersson, M. Rutberg, J. Perman
and J. Boren, Biochim. Biophys. Acta, 2009, 1791, 448–458.
K. Lubecka-Pietruszewska and K. Fabianowska-Majewska,
Analyst, 2015, 140, 2224–2235.
25 J. R. Lakowicz, Die Naturwissenschaften, 1991, 78(10), 456.
3 T. C. Walther and R. V. Farese, Annu. Rev. Biochem., 2012, 81, 26 A. T. Aron, K. M. Ramos-Torres, J. A. Cotruvo Jr and
821–2828. C. J. Chang, Acc. Chem. Res., 2015, 48, 2434.
4 S. Martin and R. G. Parton, Nat. Rev. Mol. Cell Biol., 2006, 7, 27 B. Dong, X. Song, X. Kong, C. Wang, Y. Tang, Y. Liu and
73–378. W. Lin, Adv. Mater., 2016, 28, 8755.
5 M. Nagayama, T. Uchida and K. Gohara, J. Lipid Res., 2007, 28 S. L. Chen, L. N. Yang and Z. S. Li, J. Chem. Phys., 2013,
8, 9–18. 223, 86.
2
3
4
6 R. Bartz, W. H. Li, B. Venables, J. K. Zehmer, M. R. Roth, 29 B. R. Masters, J. Biomed. Opt., 2013, 18(3), 9901.
R. Welti, R. G. W. Anderson, P. S. Liu and K. D. Chapman, 30 Z. Yang, J. Cao, Y. He, J. H. Yang, T. Kim, X. Peng and
J. Lipid Res., 2007, 48, 837–847.
J. S. Kim, Chem. Soc. Rev., 2014, 43, 4563.
17 C. Thiele and J. R. Spandl, Curr. Opin. Cell Biol., 2008, 20, 31 S. Sasaki, Y. Niko and A. S. Klymchenko, et al., Tetrahedron,
378–385.
2014, 70(41), 7551–7559.
1
1
2
8 O. J. Warburg, Cancer Res., 2009, 9, 148–163.
9 O. Warburg, et al., Biochemica, 1924, 152, 319–344.
0 Z. Zhang, Z. Yao, Y. Chen, L. Qian, S. Jiang, J. Zhou, J. Shao, 33 M. J. Jiang, X. G. Gu and B. Z. Tang, et al., Chem. Sci., 2013,
32 T. Fujimoto and R. G. Parton, Perspect. Biol., 2011, 3,
4838–4855.
A. Chen, F. Zhang and S. Zheng, Biomed. Pharmacother.,
018, 97, 339–348.
8, 5400–5446.
2
34 O. D. Young and W. Evelyn, Front. Endocrinol., 2014, 5, 115.
21 F. Baenke, B. Peck, H. Miess and A. Schulze, Dis. Model 35 A. Rohwedder, Q. Zhang, S. A. Rudge and M. J. Wakelam,
Mech., 2013, 6, 1353–1363. Cell Sci., 2014, 127, 3104.
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021
New J. Chem., 2021, 45, 4347À4353 | 4353