A "turn-on" fluorescent sensor for cytosine in aqueous media based on diamino-bridged biphenyl acrylonitrile

Article abstract of DOI:10.1039/d0nj05098a

The detection of cytosine is of significance for analyzing DNA bases, but no "turn-on"fluorescent sensor for cytosine in aqueous media has been reported so far. In this study, series of diamino-bridged biphenyl acrylonitriles 3a-3c were designed and synthesized with yields of 70-75%. The sensing experiments for 16 types of ions and biomolecules suggested that compound 3b with butanediamino bridges exhibited good selective sensing abilities towards cytosine based on "turn-on"fluorescence enhancement. The detection limit of compound 3b for cytosine attained 1.02 × 10-7 M. The selective sensing ability towards cytosine was little influenced by other species and remained stable between pH = 6-9. The sensing mechanism was proposed by the analysis of Job's plot, 1H NMR and MS binding spectra. The sensing ability for cytosine was successfully used for analysing urine samples with the recovery over 94%. Sample 3b also exhibited good bioimaging performance with bright blue-green fluorescence for sensing cytosine, implying the application prospect in complicated and living environment.

Full text of DOI:10.1039/d0nj05098a

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A“turn-on“ fluorescent sensor for cytosine in aqueous media based
on diamino-bridged biphenylacrylonitrile
hongReceived 00th January 20xx,
Accepted 00th January 20xx
Jiaojiao Chen,a,b Bangyi Zhou,a,c Yongsheng Li, Linlu Zheng, Hongyu Guo, and Fafu Yang*a, b, c
a
d
a, b
The detection of cytosine is of significance for analyzing DNA bases, but no “turn-
on“ fluorescent sensor for cytosine in aqueous media was presented so far. In this work, series
of diamino-bridged biphenylacrylonitriles 3a-3c were designed and synthesized in yields of 70-
DOI: 10.1039/x0xx00000x
www.rsc.org/
7
5%. The sensing experiments for 16 kinds of ions and biomolecules suggested that compound
3
b with butanediamino bridges exhibited good selective sensing abilities for cytosine based on
“
1
turn-on” fluorescence enhancement. The detection limit of compound 3b for cytosine attained
.02×10 M. The selective sensing ability for cytosine was little influenced by other species and
-7
kept stably between pH = 6-9. The sensing mechanism was proposed by the analysis of Job’s
1
plot, H NMR and MS binding spectra. The sensing ability for cytosine was successfully used for
analysing urine sample with the recovery over 94%. Sample 3b also exhibited good bioimaging
performance with bright blue-green fluorescence for sensing cytosine, implying the application
prospect in complicated and living environment.
Introduction
usually involved the expensive instruments, complicated
Deoxyribonucleic acid (DNA) plays the crucial roles in living body, preparation processes, long-time consumption and low sensor
1
5-21
which contains four bases (guanine, adenine, thymine and selectivity for detecting cytosine.
cytosine) to encode genetic information. Abnormal changes of effective methods are expected for selectively sensing cytosine
DNA bases in organism might indicate the irregularity in the or other DNA bases.
immunity system, and suggest the presence of various diseases
such as mental retardation, epilepsy, ageing, cancer, HIV attention due to their advantages of strong sensitivity, low cost,
infection, renal failure and cardiovascular disease. Thus, the and simple operation. Generally, the ideal fluorescent sensors
detection of qualitative or quantitative changes of four bases is have the merits including “turn-on” characteristic to reduce the
of great significance for both clinical diagnosis and study on background interference, strong emission in aqueous media
fundamental genetic information. Up to now, several analytical for the practical application,
methodologies had been used for determine DNA bases, such as low detection limit.
Hence, the simple and
1
In recent years, florescence sensors have attracted much
2
-4
2
5
5
25-28
and high sensing selectivity and
2
9
Comparing with the traditional
fluorescence dyes such as BODIPY and perylene derivatives with
6
,7
8
gas and liquid chromatography, capillary electrophoresis,
immunocytochemical method, and micellar electrokinetic ACQ effect,
chromatography.
important DNA base, was examined by various electrochemical
methods based on organic-inorganic hybrids,
plasmon resonance, and fluorescence changes of organic- polarized photoluminescence,
9
30-32
the aggregation-induced emission (AIE)
1
0-14
33-
For example, cytosine, as one of the molecules emitted the strong fluorescence in aqueous media,
3
7
exhibiting extensive application prospect in all kinds of
1
5-21
38-41
surface research fields such as luminous materials,
circularly
2
2
42,43
detection of various guests
inorganic nanocomposites.23,24 Although these reported and bio-imaging in water.44-60 However, although much progress
methods possessed their merits and advantages, they were was made for organic fluorescence sensor including AIE sensor,
it is still a considerable challenge for the precise design on
sensing complicated guests, such as DNA bases. To the best of
our knowledge, no high selective and “turn-on” fluorescent
a. College of Chemistry and Materials, Fujian Normal University, Fuzhou 350007, P.
R. China.
Fujian Key Laboratory of Polymer Materials, Fuzhou 350007, P. R. China.
Fujian provincial Key Laboratory of Advanced Materials Oriented Chemical
Engineering, Fuzhou 350007, P. R. China.
Fujian Provincial Key Laboratory of Featured Biochemical and Chemical Materials,
Ningde Normal University, Ningde 352106, P. R. China
b.
c.
probe for cytosine was presented so far. In this work, a series of
diamino-bridged biphenylacrylonitrile were designed and
synthesized for sensing DNA bases. The butanediamino-bridged
biphenylacrylonitrile exhibited good selective sensing abilities
for cytosine based on the “turn-on” fluorescence in aqueous
d.
Electronic Supplementary Information (ESI) available: Experimental details,
supporting figures and table. See DOI: 10.1039/x0xx00000x
This journal is © The Royal Society of Chemistry 20xx
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media, which was observed for organic fluorescence sensor for fluorescence spectra, which suggested the emission wavelength
the first time. Moreover, it was applied successfully for at 390-490 nm. Some red shift of the maximum emission
detecting cytosine in urine sample and bio-imaging of living wavelength and the increase of fluorescence intensities were
cells.
View Article Online
DOI: 10.1039/D0NJ05098A
observed with the increase of solution polarities, indicating the
formation of J-aggregate in high polar solution. Furthermore,
the AIE effect was studied for compounds 3a-3c in the H O/THF
2
mixtures with different water fractions. As illustrated in Figure 1
and S16-17, all of them emitted the weak fluorescence in pure
Results and discussion
Synthesis
0
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NC
THF solution. With the increase of water fractions (f
fluorescence intensities were still weak as f was smaller than
0% and increased rapidly as f was bigger than 30%. The
highest emission appeared at f = 70% for H O/THF mixtures
and the fluorescence intensities increased by 27.8, 19.3 and
5.8 times for samples 3a, 3b and 3c, respectively. The
fluorescence quantum yields were 0.30, 0.22 and 0.18 in
O/THF mixtures with f = 70% for samples 3a, 3b and 3c,
respectively. The decreasing fluorescence intensities (f > 70%)
w
), the
NC
+
OH
NaOH
EtOH
CHO
OH
w
1
3
w
O
O
O
2a: n = 2
2b: n = 4
2c: n = 6
w
2
+
Cl
DCM
O
H2N
n NH2
Cl HN
n NH Cl
Cl
O
O
1
HN
n N
H
O
H
2
w
K2CO3, KI
CH3CN
3a: n = 2
3b: n = 4
3c: n = 6
1
+ 2
w
CN
NC
were ascribed the weak solubility in these solutions. On the
other hand, the maximum emission emerged at about 440 nm
and exhibited red shifts with the increasing of water fractions,
indicating the J-aggregate in high polar solution again. All these
Scheme 1 The synthetic route for compounds 3a, 3b and 3c
2
results implied the good AIE fluorescence in H O/THF mixtures
Scheme 1 illustrated the synthetic route of target
compounds 3a, 3b and 3c. According to the published
procedure, hydroxyl-biphenylacrylonitrile 1 was obtained
smoothly by reacting benzaldehyde and p-
hydroxyphenylacetonitrile under NaOH/EtOH system. The
yield was 78% after recrystallization. On the other hand,
chlorinated diamido derivatives 2a, 2b and 2c were
based on the J-aggregate in aggregated states.
0
1
2
%
0%
0%
30%
40%
0%
0%
0%
6
1
2400
800
1200
1
5
6
7
80%
90%
5%
synthesized
in
dichloromethane
by
refluxing
9
600
ethylenediamine (butanediamine or hexamethylendiamine)
with chloroacetic chloride. Subsequently, by treating
compound 1 with chlorinated diamido derivatives 2a, 2b
and 2c in the K
target diamino-bridged biphenylacrylonitrile 3a-3c were
prepared in yields of 70-75% after rapid column
chromatography. The structures of new compounds 3a-3c
were confirmed by H NMR, C NMR, MALDI-MS and
elemental analysis (see SI). The peaks in MS spectra and the
6
2
0
CO
3
/MeCN system using KI as catalyst, the
320
400
480
560
2
Wavelength (nm)
24
18
12
6
1
13
data of elemental analysis were in accordance with the
1
“
1+2” condensation mode of samples 1 and 2. The H NMR
0%
70%
1
3
and C NMR spectra also agreed with their structures. For
1
example, only one peak in H NMR spectra was observed
for the OCH CO groups of diamino bridges, indicating the
2
symmetrical structure of “1+2” condensation mode of
compounds 3a-3c. It was worthy of noting that the soft
diamino bridges in samples 3a-3c were favorable for tuning
the complexation cavities to adapt different guests and the
amido-groups contributed to hydrogen-bond action for
binding guests, such as DNA bases and amino acids.
0
0
20
40
60
80
100
water fraction (%)
Figure 1 (upper) The emission spectra of compound 3b in
O/THF mixtures with different water fractions (λex = 320 nm,
1.0×10 M); (lower) The changes in peak intensities with
H
2
-6
different water fractions in H
fluorescence intensities in H
2
o
O/THF mixtures (I and I were the
Photophysical studies
2
O/THF mixtures with different
Firstly, the absorption and emission spectra of compounds 3a-3c water fractions and in pure THF solution); Inserted: The
were explored in series of common solvents (CH Cl , THF, CH
CN, corresponding fluorescence images.
DMF and DMSO). As shown in Figure S10-12, they exhibited
similar UV-vis spectra with the maximum absorption wavelength
at about 320 nm. Figure S13-S15 displayed the corresponding
2
2
3
2
| J. Name., 2012, 00, 1-3
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Selective fluorescence sensor for cytosine
concentration of cytosine. The plot between 0.0 eq and 0.1 eq
View Article Online
DOI: 10.1039/D0NJ05098A
of cytosine was enlarged and showed the good linear
2
As samples 3a-3c displayed the highest fluorescence in H O/THF
mixtures with f = 70%, this H O/THF system was used for
w 2
investigating the sensor abilities for series of guests. Figure 2
and S18-19 exhibited the fluorescence spectra of samples 3a-3c
relationship, which suggest the ratio of 1:1 binding
stoichiometry of compound 3b with cytosine. Furthermore,
based on the detect-limit calculating formula of DL = K×Sb1/S (K
=
2 or 3, K was set 2 here, Sb1 was the standard deviation of the
+
+
2+
2+
2+
with 8 kinds of common metal ions (Na , K , Zn , Hg , Cu ,
blank solution, S is the slope of the standard curve), the
2+
2+
+
Mg , Ca and Ag ) and 8 kinds of normal biomolecules (glucose,
urea, niacin, ascorbic acid, cytosine, guanine, thymine and
adenine). After the complexation with these tested guests, the
fluorescence spectra showed the obviously changes including
the shifts of maximum emission wavelengths and fluctuation of
maximum fluorescence intensities, indicating the strong
interaction between hosts and guests. Moreover, it can be seen
that, although samples 3a and 3c demonstrated the good
sensing abilities for cytonsine among all tested species with
enhanced fluorescence, the sensing selectivity was poor (Figure
S18 and 19). However, sample 3b exhibited the good sensing
selectivity for cytosine, accompanied by strong fluorescence
enhancement (Figure 2). The fluorescence intensities of sample
-7
detection limit of cytosine was calculated as DL = 1.02×10 M.
This value was good by comparison with the reported detection
0
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-
6
limits (0.06-10×10 M) obtained by other methods such as
electrochemical techniques (Figure S1), implying the potential
application prospect of compound 3b as sensor for cytosine.
6000
0
1
0.0 eq
0.01
0.02
0.04
5000
0.06
0.08
0.1
4
000
000
0.2
0.4
0.6
3
0.0 eq 10.0 eq
0
.8
1.0
.0
4.0
.0
8.0
0.0
3
b with cytosine (1:1) increased by 2.3 times by comparison
2000
2
with that of sample 3b. The fluorescence quantum yields
increased from 0.22 before complexation to 0.45 after binding
cytosine. The fluorescence before and after complexation
remained unchanged in five days, indicating the good
fluorescence stability. These results suggested sample 3b
possessed the good selective sensing ability for cytosine with
the “turn-on” fluorescence in aqueous media, which was
observed for organic fluorescent sensor for the first time.
Therefore, its sensing behaviour for cytosine was further studied
in details.
0.0 eq
6
1000
1
0
3
00
350
400
450
500
550
600
650
Wavelength (nm)
Figure 3. Fluorescence spectra of compound 3b in H
2
O/THF
-6
mixtures with 70% of H O (λex = 320 nm, 1.0×10 M) in the
presence of various equivalent concentrations of cytosine.
2
5500
None
glucose
urea
niacin
ascorbic acid
5
000
5000
3000
Equation
Weight
y = a + b*x
4
000
+
No Weightin
1037.66724
cytosine
Na
4500
4000
3500
3000
2500
2900
2800
2700
2600
Residual
Sum of
+
K
Squares
Pearson's r
0
.99822
2
+
Zn
Adj. R-Squar
0.99572
3000
2
+
+
Value
Standard Err
8.84691
Hg
Cu
2
B
B
Intercept
Slope
2293.3566
5885.4948
157.45058
2
+
Mg
2
000
2
+
Ca
+
Ag
2500
cytosine
guanine
thymine
adenine
1000
0
2400
2300
3
50
400
450
500
550
600
650
2200
Wavelength (nm)
0.00
0.02
0.04
0.06
0.08
0.10
2
000
Figure 2 Fluorescence spectra of the compound 3b in H
mixtures with 70% of H
presence of various metal ions and biomolecules (1.0×10 M).
2
O/THF
0
2
4
6
8
10
-
6
-6
2
O (λex = 320 nm, 1.0×10 M) in the
[
cytosine] (10 M)
-6
2
Figure 4 Fluorescence intensities of compound 3b in H O/THF
mixtures with 70% of H O (λex = 320 nm, 1.0×10 M) in the
presence of various equivalent concentrations of cytosine.
-
6
2
Fluorescence titration for cytosine
The sensing behaviour of compound 3b for cytosine was further Inserted: The enlarged plot from 0.0 to 0.1 eq of cytosine.
investigated by fluorescence titration. The complexation UV-Vis
spectra suggested the little spectral change after complexation Interference experiments and pH influence
(Figure S23). However, after adding series of different The sensing behavior of compound 3b for cytosine was also
concentrations of cytosine, the fluorescence of compound 3b in investigated in the presence of other interference species. The
H
2
O/THF mixtures with 70% of H
2
O enhanced gradually as results were summarized in Figure 5. It can be seen that the
were fluctuated around 1 in the range of 0.94-1.08,
shown in Figure 3. When the concentrations of cytosine were values of I/I
o
more than 1.0 eq., the fluorescence intensities changed little, indicating the small influence of interference species on the
indicating the achievement of complexation turning point at 1.0 fluorescence intensities of compound 3b with cytosine. These
eq of cytosine. Next, Figure 4 displayed the changes of experimental results suggested that compound 3b possesses
fluorescence intensities at 440 nm with the increase of the good selective sensing abilities for thymine in the
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complicated environments containing multiple competing
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.0
.5
.0
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10 11 12 13 14 15 16
Figure 5 Competitive experiments of 3b+cytosine with
interfering species. I and I were the fluorescence intensities of
b+cytosine and 3b+cytosine+other species, respectively. 1 =
o
3
3
1
1
1
+
+
2+
2+
b+cytosine, 2 = 1+Na , 3 = 1+K , 4 = 1+Zn , 5 = 1+Hg , 6 =
+Cu , 7 = 1+Mg , 8 = 1+Ca , 9 =1+Ag , 10 = 1+glucose, 11 =
+urea, 12 = 1+niacin, 13 = 1+ascorbic acid, 14 =1+guanine, 15 =
2
+
2+
2+
+
2
+thymine and 16 = 1+adenine. (H O/THF mixtures with 70% of
-6
1
H O, λex = 320 nm, 1.0×10 M each).
2
Figure 7 The comparison of H NMR spectra of compound 3b
lower), cytosine (upper) and 3b with cytosine (middle).
(
The pH influence on sensing behaviour was explored in the
range of pH = 4-11. As shown in Figure S20, compound 3b had
good fluorescence stability at pH = 5-9 and the fluorescence
intensities decreased when the pH < 5 or pH > 9. As the
fluorescence behaviour of 3b with cytosine, the fluorescence
intensities kept stably in the range of pH = 6-9 but the
fluorescence intensities reduced obviously as pH < 6 and >9.
These phenomena suggested the pH values made stronger
influence on fluorescence intensities of 3b with cytosine than the mixture of compound 3b with excess cytosine (1:5). Only
that of 3b, which could be ascribed to that cytosine was easily one strong peak at 721.036 was observed, which was in
influenced by pH values accompanying with the protonation in
low pH values and deprotonation in high pH values. All these
results of pH influence suggested compound 3b has stable
sensing ability in the range of pH = 6-9, which was in consistent
with the pH range of common living bodies.
The sensing mechanism of compound 3b for cytosine was
examined by fluorescence Job’s plot, H NMR spectra and MS
spectra. As shown in Figure S21, the job’s plot exhibited the
highest fluorescence change at 0.5 fraction of cytosine,
indicating the ratio of 1:1 binding stoichiometry of compound
1
3
b with cytosine. Figure 6 illustrated the MALDI-MS spectrum of
accordance with the 1:1 complex for compound 3b with
cytosine. No other complex peak was observed although excess
cytosine was added in the mixture. This result also suggested
the 1:1 sensing system for compound 3b with cytosine.
Furthermore, the H NMR spectra of compound 3b, cytosine and
their mixture (1:1) were displayed for comparison in Figure 7. It
was observed that the signals of ArH for cytosine moved from
1
Sensing mechanism
2
high field to low field, and the signals of OCH , NH and ArH also
exhibited the small shifts. These phenomena indicated both
diamino bridge and biphenylacrylonitrile units of compound 3b
were involved in sensing cytosine. Thus, based on the above
analysis and taking into account the hydrogen-bonding and π-π
stacking action, the sensing model of compound 3b with
cytosine was suggested in Figure 8. Before sensing cytosine, the
butanediamino bridge was soft chain with random
conformation, resulting in the long distance of two
biphenylacrylonitrile units for weak π-π stacking action (weak
fluorescence). After complexation with cytosine, the distance of
two biphenylacrylonitrile units was closed due to the hydrogen-
bonding and π-π stacking action, resulting in the stronger π-π
stacking of biphenylacrylonitrile-cytosine-biphenylacrylonitrile
and enhanced fluorescence finally (strong fluorescence). The
Figure 6 The MALDI-MS spectrum of 3b with cytosine (1:5).
4
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molecular theoretical orbital amplitude plots of HOMO and Thus, the fluorescence image in living cell with compound 3b or
LUMO energy levels of compound 3b before and after binding compound 3b and cytosine were investigated under confocal
View Article Online
DOI: 10.1039/D0NJ05098A
laser scanning microscopy (CLSM). Firstly, the MCF-7 cell
metabolic activity with compound 3b was explored by classical
MTT assay. The results suggested that the cell viability was over
cytosine were calculated as shown in Figure S24. The LUMO
energy level and energy gap after complexation were lower
than that before complexation, which were favorable for the
stable complexation system and high fluorescence. This
proposed sensing mechanism explained well the results of
binding spectral studies and the fluorescence enhancement of
compound 3b with cytosine.
-6
o
8
3% with 4.0×10 M of compound 3b for 24 h at 37 C (Figure
S22). Furthermore, MCF-7 cells were fixed by incubating with
o
compound 3b or 3b with cytosine for 1 h at 37 C. The
0
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fluorescence of living cells was then examined at λex = 405 nm.
The obtained fluorescence images were displayed in Figure 9. It
can be seen that the cells with compound 3b showed the weak
blue-green fluorescence and the cells with compound 3b and
cytosine displayed the bright fluorescence. These images
implied that compound 3b had the good bioimaging ability and
responded to cytosine with obvious fluorescence enhancement
in bioimaging performance. These results were in accordance
with the aforementioned fluorescence experiments in solution,
confirming again the good application prospect for sensing
cytosine in actual and living environment.
O
O
N
O
N
H
H
H
NH2
O
O
H
NH
O
N
N
NC
O
N
H
HN
O
O
NC
Long distance
Short distance
(
AIE effect based on π-π stacking
and hydrogen-bonding action)
Figure 8 The possible sensing mechanism of 3b with cytosine.
Application in urine sample
In order to test the application potential of compound 3b in
detecting cytosine in the live environment, the tap water and
urine water was added certain amounts of cytosine to be
applied for examining the fluorescence changes. The cytosine
contents in samples were calculated based on the fluorescence
changes and the comparison with standard working curve. The
results were summarized in Table 1. One can see that the
contents of cytosine detected by compound 3b in samples were
close to the added concentrations. Although the accuracies in
urine water decreased a little in comparison with that in tap
water, the recovery was still over 94%. These results confirmed
that the good application prospect for sensing cytosine in actual
samples.
Table 1 Recovery results of cytosine in samples
Total found
-
6
Sample
Found Added(10 M)
Recovery (%) Std Dev(%)
-6
(10 M)
0.97
1.95
2.94
0.94
1.89
2.90
0
0
0
0
0
0
1.0
2.0
3.0
1.0
2.0
3.0
97.0
97.5
98.0
94.0
94.5
96.9
1.8
2.4
3.2
2.2
3.1
1.7
Figure 9 Confocal fluorescence images of MCF-7 cells without or
with compound 3b (1.0×10 M) and cytosine. (A)-(C) MCF-7
cells; (D)-(F), compound 3b and MCF-7 cells; (G)-(I), compound
-6
Tap water
-6
3
b, MCF-7 cells and cytosine (1.0×10 M). Left bright field
images, middle fluorescence images, and right merged images
of fluorescence and bright field. (λex = 405 nm). The same scale
bar for all images (as shown for image G).
Urine
water
Conclusions
In conclusion, this work designed and synthesized three
diamino-bridged biphenylacrylonitriles 3a-3c in yields of
1
13
Application in living cell imaging
70-75%. Their structures were confirmed by H NMR,
C
Due to cytosine is one of the important DNA bases, it was NMR, MALDI-MS and elemental analysis. They exhibited
expected that the sensor 3b could detect cytosine in living cell. good AIE effect in H O/THF system. The sensing behaviors
2
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of samples 3a-3c for 8 kinds of common metal ions and 8 (d, 4H, J= 8.0Hz, ArH), 7.43-7.53 (m, 4H, CH and ArH), 7.69 (d,
kinds of normal biomolecules were studied by fluorescence 4H, J = 8.0Hz,ArH), 7.90 (m, 4H, ArH), 8.26(s, 2H, NH); C NMR
spectra. Compound 3b possessed good selective sensing (100 MHz, DMSO-d
abilities for cytosine based on “turn-on” fluorescence 130.74, 130.42, 130.05, 129.38, 129.04, 127.65, 115.85, 110.36,
enhancement. The detection limit attained 1.02×10 M for 67.41, 55.34; MALDI-MS (C36
cytosine. The sensing mechanism of 1:1 binding ratio was found: 605.195 [M+Na] ; Anal. Calcd. for C36
proposed based on the investigation of Job’s plot, H NMR 5.19, N 9.62; found C 74.25, H 5.22, N 9.56%.
and MS binding spectra. It had good selective sensing
ability for cytosine in the presence of other species and the 4H, CH
fluorescence kept stably between pH 6-9. The sensing 8.0Hz, ArH), 7.29 (d, 4H, J= 8.0Hz, ArH), 7.47-7.54 (m, 4H, CH
ability of sample 3b for cytosine was successfully used for and ArH), 7.71 (d, 4H, J = 8.0Hz,ArH), 7.90 (t, 4H, J = 4.0Hz, ArH),
6
analysing urine sample with the recovery over 94%. The 8.18(s, 2H, NH); C NMR (100 MHz, DMSO-d ) δppm: 167.64,
bioimaging experiment of MCF-7 cells with sample 3b 158.81, 141.45, 134.01, 130.76, 130.41, 130.06, 129.39, 129.05,
suggested that 3b possessed good bioimaging performance 127.67, 115.85, 110.39, 67.49, 55.34, 26.96; MALDI-MS
with enhanced bright blue-green fluorescence on sensing (C38
cytosine, suggesting the potential application prospect of Calcd. for C38
detecting cytosine in complicated and living environment.
View Article Online
DOI: 10.1039/D0 N1 3J 05098A
6
) δppm: 168.30, 158.92, 141.36, 134.35,
-
7
+
H
30
N
4
O
4
) [M] : Calcd.: 582.227.
+
H
30
N
4 4
O : C 74.21, H
1
1
Compound 3b: H NMR (400 MHz, DMSO-d
6
) δppm: 1.44(s,
0
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2
3
4
5
6
7
8
9
0
1
2
3
4
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7
8
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3
4
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1
2
3
4
5
6
7
8
9
0
2
), 3.14 (s, 4H, NCH
2
), 4.54(s, 4H, OCH
2
), 7.09 (d, 4H, J =
1
3
+
+
H
34
N
4
O
4
) [M] : Calcd.: 610.258. found: 611.061[MH] ; Anal.
: C 74.73, H 5.61, N 9.17; found C 74.76, H
34 4 4
H N O
5.65, N 9.11%.
Compound 3c: 1H NMR (400 MHz, DMSO-d
) δppm:
6
1
4
.23(bs, 4H, CH
H, OCH
2
), 1.41(bs, 4H, CH
2
), 3.12 (bs, 4H, NCH
2
), 4.50(s,
2
), 7.09 (d, 4H, J = 8.0Hz, ArH), 7.29 (d, 4H, J= 8.0Hz,
ArH), 7.47-7.54 (m, 4H, CH and ArH), 7.71 (d, 4H, J = 8.0Hz,ArH),
.91 (t, 4H, J = 4.0Hz, ArH), 8.11(s, 2H, NH); C NMR (100 MHz,
) δppm: 167.60, 158.77, 141.43, 133.96, 130.69, 130.40,
30.06, 129.37, 129.05, 127.65, 115.97, 113.11, 67.27, 56.52,
) [M] : Calcd.: 638.289.
found: 638.976[M] , 661.293[M+Na] ; Anal. Calcd. for
Experimental
1
3
7
Chemicals and methods
DMSO-d
6
1
2
The chemical reagents were supplied by commercial company
(Aladdin LLC). The organic solvents were treated by standard
anhydrous procedure before use. Pre-coated glass plates were
applied for TLC analysis. Column chromatography was carried
out on silica gel (200-300 mesh). NMR spectra were performed
in the solvent of CDCl
instrument at 26 C. Bruker mass spectrometer was used for
recording the MS spectra. Elemental analyses were analysed on Methylthiazolyldiphenyl-tetrazolium (MTT) method was applied
Vario EL IIIElemental Analyzer. UV-Vis spectra were measured to detect the toxicity of MCF-7 cancer cells. The Inoculated MCF-
on Varian UV-Vis spectrometer. Fluorescence spectra were 7 cancer cells were cultivated under the condition of 37 C and
examined on the Hitachi F-4500 spectrometer. The fluorescence 5% CO for 24 hours. After 24 h of cultivation, 1.0×10 M of
F
absolute quantum yield (Φ ) was obtained on FLS920 sample 3b was traced in the cells. Then, the cells were washed
Fluorescence instrument with a 6-inch integrating sphere. with PBS buffer and fostered in 0.5 mg/mL MTT-PBS buffer for 3
Compound 1 and 2a-2c were prepared according to the hours. Finally, 100 μL of DMSO was added to dissolve the
literatures.
Science, Fujian Normal University.
+
9.44, 26.42; MALDI-MS (C40
H
38
N
4
O
4
+
+
C
8
40 38 4 4
H N O : C 75.21, H 6.00, N 8.77; found C 75.27, H 6.04, N
.69%.
3
or DMSO-d
6
on the Bruker-ARX 400
MTT Assay
o
o
-6
2
6
1,62
The MCF-7 cells were supplied by college of Life appeared Formazan crystals, and the absorption intensity was
examined at 490 nm.
Synthesis of compounds 3a, 3b and 3c
The experiment of living cell imaging
Under N
mmol) and compound 2a (2b or 2c ) (0.5 mmol) was stirred and diluted to concentration of 1.0×10 M by PBS buffer (pH = 7.4)
refluxed in 20 mL of dry MeCN for 24 h with dry K CO (0.41g, 3 for imaging test. MCF-7 cancer cells were fostered under the
mmol) and KI (0.10g, 0.6 mmol) as catalyst. The disappearance same MTT condition for 24 hours, further stained with 1.0×10
of starting materials was examined by TLC detection. M of compound 3b, further rinsed with PBS buffer, and treated
Subsequently, 30 mL of HCl solution (1 M) and 30 mL of CH
were added in reaction system under stirring. Then the mixture obtained cells were imaged under the observation of confocal
was partitioned and the organic layer was dried by anhydrous laser scanning microscope (CLSM, Zeiss LSM 710, Jena,
2
atmosphere, the mixture of compound 1 (0.22 g, 1 Compound 3b (3.0 mg) was dissolved in DMSO (1 mL), then
-6
2
3
-6
-
6
o
2
Cl
2
in solution of cytosine (1.0×10 M) at 37 C for 1 hour. Then, the
MgSO
reduced pressure. The residue was purified by rapid column
chromatography (eluent: CH Cl
were obtained as pale yellow solid in yields of 72%, 70% and
5%, respectively.
Compound 3a: H NMR (400 MHz, DMSO-d
s, 4H, NCH ), 4.54(s, 4H, OCH ), 7.09 (d, 4H, J = 8.0Hz,ArH), 7.29
4
. The organic layer was further concentrated under Germany).
2
2
). Compounds 3a, 3b and 3c Compliance with ethical standards
7
Ethical approval
1
6
) δppm: 3.28
All procedures in this work concerning human participants were
performed in accordance with the Guidelines of 1964 Helsinki
(
2
2
6
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Declaration and its later amendments or comparable ethical 18. B. Zhu, M. A. Booth, P. Shepherd, A. Sheppard and J. Travas-
standards and approved by the ethics Committee at Fujian
Normal University.
View Article Online
DOI: 10.1039/D0NJ05098A
Sejdic, Biosens. Bioelectron., 2015, 64, 74-80.
19. X. Hou, Z. Li, Y. Wang, B. Li, C. Liu, Q. Zhan, G. Liu, D. Wei
and Z. Xu, J. Photochem. Photobio. A: Chem., 2020, 386,
12090.
0. S. Kundu, P. K. Maiti and P. Sahoo, Asian J Org. Chem., 2020,
, 94-98
1. M. Peng, H. Wang, G. L. Gibson, H. Shang; J. Yang, Y. Chen
and Y. Lu, J. Braz. Chem. Soc., 2020, 31, 305-312.
2. A. Kobori, S. Horie, H. Suda, I. Saito and K. Nakatani, J. Am.
Chem. Soc., 2004, 126, 557-562.
3. C. A. Huerta-Aguilar, B. Ramírez-Guzmán, P. Thangarasu, J.
Narayanan and N. Singh, Photochem. Photobiol. Sci., 2019,
8, 1761-1772.
4. W. Y. Xie, W. T. Huang, N. B. Li and H . Q. Luo, Analyst, 2011,
36, 4130-4134.
5. A. R. Longstreet, M. Jo, R. R. Chandler, K. Hanson, N. Zhan, J.
J. J. Hrudka, H. Mattoussi, M. Shatruk and D. T. Mcquade, J.
Am. Chem. Soc., 2014, 136, 15493-15496.
1
Informed consent
2
2
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Informed consent was obtained from all human participants of
this study.
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Conflicts of interest
The authors declare that they have no conflict of interest.
1
Acknowledgements
2
2
Financial support from the National Natural Science
Foundation of China (No: 21406036), Fujian Science and
Technology Project (No. 2019N0010), Fujian Provincial Key
Laboratory of Featured Biochemical and Chemical Materials
(FJKL_FBCM202006) and Undergraduate innovation 26. H. T. Feng, J. W. Y. Lam and B. Z. Tang, Coord. Chem. Rev.,
program of FJNU (2021) were greatly acknowledged.
1
2020, 406, 213142.
27. J. Qiu, S. Jiang, B. Lin, H. Guo and F. Yang, Dyes Pigm., 2019,
170, 107590.
28. S. Jiang, J. Qiu, Z. Wang, H. Guo and F. Yang, Spectr. Acta
Part A, 2020, 229, 117916.
29. J. Mei, Y. Huang and H. Tian, ACS Appl. Mater. Interf., 2018,
10, 12217-12261.
0. Z. Yan, X. Lin, H. Guo and F. Yang, Tetrahedron Lett., 2017,
8, 3064-3068.
1. M. Zhu, Z. Wang, F. Yang and H. Guo, Dyes Pigm., 2016, 133,
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New Journal of Chemistry
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View Article Online
DOI: 10.1039/D0NJ05098A
A“turn-on“ fluorescent sensor for cytosine in aqueous
media was prepared.
O
O
N
O
N
H
H
H
NH2
O
O
H
NH
O
N
N
NC
O
N
H
HN
O
O
NC
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Long distance
Short distance
(
AIE effect based on π-π stacking
and hydrogen-bonding action)