Fluorescence “On-Off” chemical sensor for ultrasensitive detection of Al3+ in live cell

Article abstract of DOI:10.1016/j.tetlet.2020.151893

An efficient fluorescent probe, 3, 3-bis(4-hydroxyphenyl)-2-benzofuran-1-one-isoquinoline-1-carbohydrazide hydrazine (L), has been prepared for the selective sensing of Al³⁺ in DMSO-H₂O (90:10, v/v) solution. The 1:2 stoichiometry of

Full text of DOI:10.1016/j.tetlet.2020.151893

Tetrahedron Letters xxx (xxxx) xxx
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Tetrahedron Letters
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Fluorescence ‘‘On-Off” chemical sensor for ultrasensitive detection
3
+
of Al in live cell
Jinli Zhu a,c,1, Linxia Lu
b,c,1
, Miao Wang , Tongming Sun , Yang Huang b,c, Chunxian Wang a,c
a,c
a,c
,
a,c
a,c,
⇑
a,c
a,c,
⇑
Wenyan Bao , Minmin Wang
, Fengxia Zou , Yanfeng Tang
a
School of Chemistry and Chemical Engineering, Nantong University, Nantong 226019, PR China
School of Textiles, Nantong University, Nantong 226019, PR China
Nantong Key Laboratory of Intelligent and New Energy Materials, PR China
b
c
a r t i c l e i n f o
a b s t r a c t
Article history:
An efficient fluorescent probe, 3, 3-bis(4-hydroxyphenyl)-2-benzofuran-1-one-isoquinoline-1-carbohy-
Received 16 February 2020
Revised 5 March 2020
Accepted 31 March 2020
Available online xxxx
3+
2
drazide hydrazine (L), has been prepared for the selective sensing of Al in DMSO-H O (90:10, v/v)
3+
solution. The 1:2 stoichiometry of L and Al was determined from Job’s plot experiments and ESI-MS.
10
À2
À9
The binding constants was observed as 7.106 Â 10
M
, and the detection limit is 9.79 Â 10 M.
3
+
Moreover, the as-prepared probe shows high sensitivity to Al both in acidic and neutral conditions.
In addition, the as-prepared probe with good biological compatibility shows effective imaging of Al
in living cells.
3+
Keywords:
Schiff base
Ó 2020 Published by Elsevier Ltd.
Fluorescent probe
3+
Al sensing
Cell imaging
Introduction
suitable for organic solvents or mixed aqueous in a narrow pH
range, which limited the utilization in practical samples. Therefore,
a more sensitive probe with fast analysis, wide pH response, highly
sensitive and selective is still required to be developed in practical
utilization. Phenolphthalein with properties of low biotoxicity and
abundant N and O sites has attracted great attention in Schiff base
based fluorescent probe [26,27].
In recent years, newly synthesized molecular probes with highly
sensitivity, selectivity and eco-friendly have attracted great atten-
tion in various fields [1–4]. Especially, molecular based fluorescent
probes had attracted a keen attention due to their highly potential
applications in the field of ecological as well as therapeutic [5–9].
Although some advancements have been made in designing and
applying molecular-based materials for highly specific and selec-
Herein, we designed and synthesized a novel Schiff base fluo-
rescent probe of 3, 3-bis(4-hydroxyphenyl)-2-benzofuran-1-one-
isoquinoline-1-carbohydrazide hydrazine (L). It is synthesized
from phenolphthalein and isoquinoline hydrazide. As expected, L
2
+
2+
2+
3+
3+
tive for Cu , Zn , Hg , Fe , Al or other transition metal ions
10–15]. Despite being a non-essential element, the detection of
[
3
+
3+
Al is of great interest due to its potential toxicity, for example,
exhibits excellent sensitivity and selectivity for Al , and the detec-
3
+
À9
excessive Al could cause Alzheimer’s disease [16], adolescent
mental retardation [17], osteoporosis [18] and impede the absorp-
tion of various trace elements [19]. Therefore, sensitive detection of
tion limit is 9.79 Â 10 M which is much lower than previous
reported sensors. Moreover, the potential photoinduced electron
transfer sensing mechanism was proposed by ESI-MS and Job’s plot
analysis. More importantly, the as-prepared L probe shows high
3
+
Al is crucial in controlling its concentration levels in the organism.
Among previous reported fluorescent probes [20–22], Schiff
base as an excellent ligand with unique photophysical properties
has attract great attention in designing molecular sensor. Even
though Schiff base probes have made some progress in detecting
3
+
sensitivity to Al in 3–7 pH range, and the as-prepared probe with
3+
good biological compatibility could be used to image Al in living
cells.
3
+
Al metal ions [23–25], previous reported molecules are mostly
Results and discussion
⇑
Corresponding authors at: School of Chemistry and Chemical Engineering,
Nantong University, Nantong 226019, PR China.
3
+
Fluorescent sensing of Al
E-mail addresses: mmwang0528@ntu.edu.cn (M. Wang), tangyf@ntu.edu.cn
Y. Tang).
J.L. Zhu and L.X. Lu contributed equally to this work.
The fluorescence responses of the L towards various metal ions
were carried out in DMSO-H O (90:10, v/v) at pH = 7.4. As shown in
(
1
2
https://doi.org/10.1016/j.tetlet.2020.151893
040-4039/Ó 2020 Published by Elsevier Ltd.
0
Please cite this article as: J. Zhu, L. Lu, M. Wang et al., Fluorescence ‘‘On-Off” chemical sensor for ultrasensitive detection of Al3+ in live cell, Tetrahedron
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2
J. Zhu et al. / Tetrahedron Letters xxx (xxxx) xxx
Fig. 1a, upon excitation at 377 nm, L exhibit a very weak emission
band near 479 nm, while the fluorescent intensity of the composite
was significantly enhanced after the adding of Al3 due to the pho-
toinduced electron transfer (PET) and isomerization of AC@N [28–
ions change the emission performance of the as-prepared L. As
directly shown in Fig. S8, L also exhibited a distinguishable naked
eye sensing property toward Al . The optical photographs under
365 nm UV light (inset of Fig. 1) indicated an obvious fluorescence
emission change from colourless to yellow in the absence and pres-
+
3+
3
1]. Notably, under similar experiment conditions, no other metal
M) in the absence and presence of Zn2+, Cr3+, Ag , Mg2+, Ba2+, Na , Ni , Pb2+, Hg2+, Al3+, Mn2+, Co2+, Cu2+, Cd2+, K , Li , Fe2+, Ca2+
M) in the presence of selected metal ions (100 M). (c) Fluorescence spectra of L (10 M) in the presence of increasing concentrations
of Al3+ and (d) its corresponding limit of detection of L for Al . All fluorescence analysis was studied in DMSO-H
O (90:10, v/v, HEPES = 20 mM, pH = 7.4).
+
+
+
+
+
,
Fig. 1. (a) Fluorescence spectra of probe L (10
l
3+
Fe . (b) Fluorescence intensity of L (10
l
l
l
3+
2
3+
2
Fig. 2. (a) A Job’s plot showing 1:2 ratio stoichiometry of the complex between L and Al in DMSO-H O (90:10, v/v, HEPES = 20 mM, pH = 7.40). (b) ESI-Mass spectrum of
L-Al3+-NO
k
À
complex. (c) Association constant of L for Al through fluorescent intensity, assuming 1: 2 stoichiometry for association between L and Al in methanol,
3+
3+
3
ex = 377 nm, kem = 479 nm. (d) A possible mechanism of probe L in sensitive detection of Al3 in our system.
+
Please cite this article as: J. Zhu, L. Lu, M. Wang et al., Fluorescence ‘‘On-Off” chemical sensor for ultrasensitive detection of Al3+ in live cell, Tetrahedron
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J. Zhu et al. / Tetrahedron Letters xxx (xxxx) xxx
3
ence of Al3+. More interestingly, even coexistent metal ions make
tron-transfer (PET) phenomenon from lone pair electrons of the
Schiff-base nitrogen atom to the chromonemoiety. Interestingly,
as shown in Fig. 1c, with increasing addition of Al (0–6 eq.) into
3+
little influence on the emission intensity of L-Al
complex
2+
3+
(
Fig. 1b) except for the addition of Cu , which the fluorescence
3
+
2+
of L-Al is quenched by the paramagnetic effect of Cu . All the
results demonstrated the high sensing selectivity of our prepared
probe L. Subsequently, the fluorescence emission titration spectra
the solution of probe L, the fluorescence intensity enhanced grad-
ually, and its intensity increased by more than 700-fold with the
value of fluorescence quantum yield changing to 0.032. That phe-
3+
3+
of probe L with increasing amounts of Al were studied to explore
the sensitivity of the prepared probe L. As shown in Fig. 1c, the flu-
orescence emission of probe L alone was extremely weak with a
low quantum yield value of 0.0012 in quinoline sulfate, which
was due to the fluorescence quenching by the photoinduced elec-
nomena were induced by the chelation of probe L with Al , which
would lead to the chelation-enhanced fluorescence (CHEF) process
due to the interruption of the PET phenomenon, thereby restoring
the fluorescence emission of the probe L. The detection limit of
3
+
probe L for recognizing Al was evaluated to be as low as
À9
9
.79 Â 10 M level (Fig. 1d), which was low enough for L to detect
3
+
and control Al in the environmental and biological systems and
was lower than US EPA defined tolerable levels of Al in drinking
3
+
water [32]. Thus, the probe L could be used as a selective fluores-
3
+
cent sensor for sensitive detection of Al in many chemical and
biological systems.
Bonding mode studies
Continuous variation (Job’s plot) analysis was further demon-
strate the chemical reaction stoichiometry between Al3+ and probe
L. During this experimental process, the total concentration of
3
+
probe L and Al was kept constant at 10.0 lM with a continuous
3
+
variable molar fraction of the host ([L]/[L-Al ]). As demonstrated
in Fig. 2a, the fluorescence value at 489 nm approached a maxi-
mum when the molar fraction of probe L was 0.33, which meant
3
+
that probe L formed a 1: 2 complexes with Al . Additionally, the
formation of this 1: 2 complexes was further confirmed by the
appearance of a characteristic peak at m/z 444.3 assignable to
3
+
À
+ 2+
3+
[
L + 2Al + 2NO
3
À 2H ] in the ESI-MS spectrum of L-Al com-
Fig. 3. Effect of pH value on fluorescence intensity of the L (10 lM) and L with 10
equiv of Al3 + in DMSO-H2O (90:10, v/v, HEPES = 20 mM, pH = 7.40). kex = 377 nm,
+
À
plex and the characteristic peak at m/z 711.5 assignable to [L - H ]
kem = 479 nm.
(Fig. 2b). On a basis of 2:1 ratio stoichiometry between probe L and
Fig. 4. (a) Cell viability of Hela cells treated with various concentration (0–100
incubated with the probe L. (c) Fluorescent image of Hela cells incubated with L (10
l
M) of the sensor L determined by MTT assay. (b) Optical transmission images of HeLa cells
M) and (d) fluorescent image in presence of L-Al3 (100
+
lM).
l
Please cite this article as: J. Zhu, L. Lu, M. Wang et al., Fluorescence ‘‘On-Off” chemical sensor for ultrasensitive detection of Al3+ in live cell, Tetrahedron
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4
J. Zhu et al. / Tetrahedron Letters xxx (xxxx) xxx
Al3+, the association constant K of probe L with Al was then cal-
3+
Acknowledgements
1
0
À2
culated to be 7.106 Â 10
M
from fluorescence titration exper-
iments with a good linear relationship by the Benesi-Hildebrand
equation (Fig. 2c). Therefore, based on the above results, a possible
sensing mechanism was proposed as shown in Fig. 2d, with the
This work was financially supported by the National Natural
Science Foundation of China (Grant Nos. 21776140) and Natural
Science Foundation of Jiangsu Province (BK20190918) and Natural
Science Research Projects of Universities in Jiangsu Province
(19KJB430030). Nantong Science and Technology Bureau Project
(JC2018123). We are also very grateful to the Nantong University
Analytical Testing Center for its support for testing.
3
+
3+
addition of Al , the chelate formed by L and Al , which would
lead to the chelation-enhanced fluorescence (CHEF) process due
to the interruption of the PET phenomenon on pure L, thereby
restoring the fluorescence emission of L.
pH effect
Appendix A. Supplementary data
Besides of efficient sensitivity and selectivity, the sensing ability
in various acidity for probe is sessional for practical using. We
Supplementary data to this article can be found online at
https://doi.org/10.1016/j.tetlet.2020.151893.
study the sensing ability by tuning the pH of DMSO-H
2
O from
2
.5 to 11.5. As shown in Fig. 3, the pure probe L shows little fluo-
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Declaration of Competing Interest
The authors declare that they have no known competing finan-
cial interests or personal relationships that could have appeared
to influence the work reported in this paper.
Please cite this article as: J. Zhu, L. Lu, M. Wang et al., Fluorescence ‘‘On-Off” chemical sensor for ultrasensitive detection of Al3+ in live cell, Tetrahedron
Letters, https://doi.org/10.1016/j.tetlet.2020.151893