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MoS2 quantum dots-combined zirconium-metalloporphyrin frameworks: Synergistic effect on electron transfer and application for bioassay
Accepted Manuscript Title: MoS2 quantum dots-combined zirconium-metalloporphyrin frameworks: Synergistic effect on electron transfer and application for bioassay Authors: Wen-Li Xin, Lian-Fu Jiang, Li-Ping Zong, Hai-Bo Zeng, Guo-Fang Shu, Robert Marks, Xue-ji Zhang, Dan Shan PII: DOI: Reference:
S0925-4005(18)31195-X https://doi.org/10.1016/j.snb.2018.06.090 SNB 24927
To appear in:
Sensors and Actuators B
Received date: Revised date: Accepted date:
4-4-2018 15-6-2018 19-6-2018
Please cite this article as: Xin W-Li, Jiang L-Fu, Zong L-Ping, Zeng H-Bo, Shu G-Fang, Marks R, Zhang X-ji, Shan D, MoS2 quantum dots-combined zirconium-metalloporphyrin frameworks: Synergistic effect on electron transfer and application for bioassay, Sensors and Actuators: B. Chemical (2018), https://doi.org/10.1016/j.snb.2018.06.090 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Ms.Ref.No.: SNB-D-18-01460
MoS2 quantum dots-combined zirconium-metalloporphyrin frameworks: Synergistic effect on electron transfer and
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application for bioassay Wen-Li Xin,† Lian-Fu Jiang,† Li-Ping Zong,† Hai-Bo Zeng,†* Guo-Fang Shu, ‡
†MIIT
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Robert Marks,§ Xue-ji Zhang,¿ Dan Shan†*
Key Laboratory of Advanced Display Materials and Devices, School of
Environmental and Biological Engineering, Nanjing University of Science and
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of Clinical Laboratory, Zhongda Hospital, Affiliated to Southeast University,
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‡Centre
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Nanjing 210009, China
Department of Biotechnology Engineering, Ben-Gurion University of the Negev,
Beer-Sheva, Israel.
School of chemistry and biological engineering, University of Science and
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¿
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§
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Technology, Nanjing 210094, China
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Technology Beijing, Beijing 100083, China
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*Corresponding author: Email: [email protected] (D. Shan) [email protected] (H.B. Zeng) Fax: 0086-25-84303107 1
The ECL emission of singlet oxygen in aqueous media was originated from
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Highlights
successive electro-reduction of zinc porphyrin in MOF-545-Zn as electron media
MOF-545-Zn could be functionalized with the 2D-MoS2(MQDs) and enhanced
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reacting with O2 in the 3D nanocage.
Modified by lipoic acid, the as-synthesized MOF-545-Zn@MQDs was further
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ECL intensity was obtained due to the synergetic effect of the O2 electrocatalysis.
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used as signal amplifying probes for ultrasensitive ECL CEA assay.
ABSTRACT
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In this study, 2D-MoS2 quantum dots (MQDs) were combined with the zirconium based porphyrinic metal-organic framework (MOF-545-Zn) through simple ultrasonic method for the purpose of the enhanced electrochemiluminescence (ECL). In addition, electrochemiluminescence (ECL), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed to investigate the synergistic effect on 2
electron transfer of the composite. MQD loading with confined orientation on the surface of MOF-545-Zn was confirmed by morphology and spectroscopy. Moreover, from hybrids material, the higher ECL intensity was received. MOF-545-Zn@MQDs was functionalized by alpha lipoic acid (LA) and was further applied to develop a
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novel ECL immunosensors for carcinoembryonic antigen (CEA).
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Keywords: electrochemiluminescence, metal-organic framework, 2D-MoS2 quantum dots, immunoassay
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1 INTRODUCTION
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The electrochemiluminescence (ECL) is a powerful analytical tool and has been
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widely applied in multiple fields[1]. In most cases, the ECL system is composed of
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luminophore (electrochemical process) and co-reactant (chemical reaction) [2].
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Recently, the electrochemical studies utilized metal complexes, luminol, and nanomaterials as ECL luminophore. The core issues of ECL are response intensity and
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co-reaction efficiency. New ECL system has attracted much attention due to the high efficiency and excellent stabilities [1]. Metal-organic frameworks (MOFs) are
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multifunctional materials which consist of metal moieties and organic ligand bridges. Because of chemical functionalities, tunable pore sizes, and large surface areas, MOFs
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have been widely used in gas storage/separation, catalysis, sensing, and drug delivery[3-5]. MOFs, made metal porphyrin as organic ligand, have also been reported to act as ECL luminophores [6-9]. The Zr-based MOFs have been synthesized variously[9-12], thereinto, the MOF-525-Zn can be served as an ECL luminophore because of it has excellent ECL response and stability[13]. Furthermore, 3
our previous work utilized MOF-525-Zn established a new ECL systems which combined with MOF-525-Zn and O2, was successfully used in biosensor[11, 14]. However, in this system, the Zn-TCPP numbers in the MOF-525-Zn surface are less than that in the MOF-545-Zn surface[15]. Therefore, the MOF-545-Zn was used to synthesized composites in this work.
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Moreover, the electron transfer efficiency is an important part in ECL progress， although, enhanced electron transfer efficiency was an important way to achieve
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higher ECL intensity. The MoS2 was a typical two-dimensional material, have lately attracted much attention as an energy acceptor in resonance energy transfer because of
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their special properties in nanoelectronics, optoelectronics, and energy harvesting
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properties [16, 17]. the MoS2 nanosheets have multimethod to prepare, such as
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micromechanical cleavage, lithium interaction, liquid exfoliation, hydrothermal
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reaction, chemical reaction [18-22]. Moreover, while the size of MoS2 was controlled to be less than 10 nm, MoS2 quantum dots (MQDs) has been synthesized. The MQDs
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possess unique optical and electronic properties and are potentially applicable in fluorescence sensing, catalysis, bioimaging because of quantum confinement and
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edge effect[23]. The MQDs has excellent gas absorb property and be used to gas
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sensor [24, 25]. Based on the MQDs can catalytic O2 reaction and absorbed, in the other hand the O2 was better co-reactant in ECL process of MOF-545-Zn, composites the MQDs with MOF-545-Zn could received a composite which have higher ECL
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response.
2 EXPERIMENTAL 2.1 Materials and Reagents Zirconium (IV) chloride, N, N-dimethylformamide (DMF), sodium salt (HEPES) 4
were purchased from Sigma-Aldrich Chemical Co., Ltd. (Shanghai, China). Zn-meso-tetra (4-carboxyphenyl) porphyrin (Zn-TCPP) was bought from J&K Scientific Ltd. (Shanghai, China). All other reagents were of analytical grade and were used without further purification. Ultrapure water obtained from a Millipore water purification system (≥18 MΩ, Milli-Q, Millipore) was used as the water source
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throughout the work. The 10 mM pH 7.4 HEPES containing 0.3 M KCl solution was employed as an aqueous electrolyte solution for photoelectrochemical and
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electrochemical measurements. 2.2 Characterization
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ECL measurements were carried out on an MPI-E multifunctional electrochemical
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and chemiluminescent analytical system (Xi’an Remex Analytical Instrument Co., Ltd,
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China). Photoluminescence (PL) was recorded by an Edinburgh FLS920 fluorescence
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spectrometer (Livingston, UK). All electrochemical measurements were carried out
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on a CHI 660D (Chenhua, China) at room temperature. All electrochemical studies were performed with a conventional three electrode system. The Ag/AgCl electrode
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and Pt wire electrode was used as reference and counter electrode, respectively. A modified glassy carbon (GCE, 3 mm in diameter) was used as working electrode.
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Before modification, the GCE was polished carefully with 0.3 and 0.05 m of α-Al2O3 powder, subsequently, washed with ethanol and ultrapure water in proper
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order, blow dry with N2 and packaging electrode with TOAB when accomplish modified. Electrochemical impedance spectroscopy (EIS) measurements were carried out using an Autolab PGSTAT30 (Eco chemie, The Netherlands) controlled by NOVA 2.0 software. The morphology was investigated with a XL-30E scanning electron microscope (SEM). Powder X-ray diffraction patterns (PXRD) were recorded on a 5
Bruker D8-Focus Bragg Brentano X-ray Powder diffract meter equipped with a Cu sealed tube (λ = 1.54178 Å) at room temperature. The ultraviolet absorption spectra were measured by UV-vis spectrophotometry (UV-3600, Shimadzu, Japan). The X-ray photoelectron spectroscopy (XPS) experiments were carried out on K-Alpha (Thermo Fisher Scientific Co., USA). Deoxygenated deionized water obtained by
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bubbling N2 to remove O2 from the water.
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2.3 Preparation of MOF-545-Zn@MQDs composites
The MOF-545-Zn was synthesized according to the previously reported hydrothermal method[15]. Zirconyl chloride octahydrate (37.5 mg) was added to 10 mL DMF and
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sonicated for 0.5 hours. Following sonication, Zn (II) meso-tetra (4-carboxyphenyl)
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porphyrin (6.5 mg) was added to the mixed solution. After a further ten minutes of
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sonication, 7 mL of formic acid was added. The mixture was placed into 20 mL
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scintillation vials and heated at 130 °C for three days. The samples were collected by
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filtration and washed with DMF. The DMF was then replaced with acetone over a five day period. Finally, the volatile acetone was removed by heating at 120 °C under
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vacuum for 48 hours. In addition, the MQDs were obtained via two step method, the n-butyl lithium intercalation[26] and ultrasonic liquid exfoliationc[27]. Firstly, in
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glove box, 0.8 g bulk MoS2 was suspended in 15 mL n-Butyl lithium (n-Hexane) and transferred to a 50 mL Teflon-lined stainless steel autoclave then kept at 90 oC for 12 hours. Following, the mixture was washed with n-Hexane in glove box and then
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solvent was removed by heating at 30 oC under vacuum for 48 h. Next, decentralized solid in deoxygenated deionized water and probe sonicated for 2 h, the resulting mixture was centrifuged at 4000 rpm for 60 minutes, to remove sediment solid and obtained MQDs suspension. 6
The MOF-545-Zn@MQDs composite was obtained with ultrasonic compositeness. Briefly, mixed isovolumetric 10 mg L-1 MQDs and 30 mg mL-1 MOF-545-Zn, the MOF-545-Zn@MQDs suspension was obtained after the mixture ultrasonicated for 0.5 hours.
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2.4 Fabrication of CEA biosensor The procedure for the preparation of ECL immunosensor for CEA was illustrated in
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Scheme 1. Initially, MOF-545-Zn@MQDs modified electrode was obtained by coating GCE with 10 L of MOF-545-Zn@MQDs mixture (20 mg mL-1) and dried
under ambient temperature. For the purpose of biomodification, 10 L LA (5 mg L-1)
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was pipetted onto the MOF-545-Zn@MQDs modified electrode and kept for 30
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min[28]. The above prepared electrode was further activated by 20 mg mL-1 of
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EDC/NHS(c (EDC) =20 mg mL-1, c (NHS) =10 mg mL-1) for 0.5 hours. Subsequently,
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the above electrode was incubated at 4 oC with 10 L of CEACAM5 ( one of the
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antibodies of CEA.) solution (0.01 mg mL-1, 0.01 M PBS, PH 7.4) for 12 hours. Finally, 10 μL of 1 wt% BSA as a blocking reagent was dropped onto the surface of
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electrode for 1 hours to eliminate nonspecific binding effects.
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3 RESULTS
3.1 ECL Investigation
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Practically, MQDs were combined with MOF-545-Zn via a simple ultrasonic method. The ECL behavior of the obtained MOF-545-Zn@MQDs was investigated. GCE/MOF-545-Zn@MQDs
was
feasibly prepared
by
casting
10
L of
MOF-545-Zn@MQDs solution (20 mg mL1) on the surface of GCE and dried at ambient temperature. GCE/MOF-545-Zn and GCE/MQDs were fabricated following 7
the same procedure and used as a control. Fig. 1 showing the ECL files of the modified electrode in HEPES (10 mM) buffer solution. In the O2-saturated environment, no obvious ECL signal can be observed at GCE/MQDs (curve a of Fig. 1A). Moreover, for the case of GCE/ MOF-545-Zn and GCE/MOF-545-Zn@MQDs, the maximum ECL response intensity can be found at 3088 a.u. and 9177 a.u., (curve
b,
c
of
Fig.
1A).
The
ECL
responses
of
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respectively,
GCE/MOF-545-Zn@MQDs are illustrated in Fig. 1B, which was obtained during a
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continuous potential scan, showing constant and stable signals and the relative
standard deviation (RSD) was just 3.7 %, respectively. The effect of O2 on the ECL
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response of GCE/MOF-545-Zn@MQDs was also evaluated (Fig. 1C) and no signal
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response was observed in the deoxygenated environment (curve a of Fig. 1C). ECL
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response intensity for the saturated air and O2 can be observed at 3562 a.u. and 9294
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a.u.(curve b, c of Figure 1C).
In addition, the photoluminescence properties of the composites were investigated.
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The photoluminescence spectra of MQDs exhibits a peak at 488 nm (curve a of Fig. 1D) and the photoluminescence emission peaks of the MOF-545-Zn@MQDs,
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MOF-545-Zn, and Zn-TCPP are expressing in curve b, c, and d of Fig. 1D. The ECL
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spectrum of GCE/MOF-545-Zn@MQDs in the O2-saturated aqueous electrolyte solution biased at -1.68 V was performed that ECL emission occurred in the range of 400-700 nm and the maximum wavelength is at 642 nm (inset of Fig. 1D).
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3.2 Electrochemical Investigation Cyclic voltammetry (CV) was used to analyze electrochemical behaviors of the MOF-545-Zn, MQDs and MOF-545-Zn@MQDs in HEPES (10 mM) buffer solution system, the continuous potential scan rate was between -1.8 V to - 0 V and 100 mV s-1. 8
As the MOF-545-Zn CV (Fig. 2A) in the deoxygenated environment (curve a), a reduction peak can be observed. Meanwhile in saturated oxygen environment (curve b), reduction peak of the dissolved oxygen was found at -0.65 V and onset potential near -0.26 V, other two reduction peaks -1.20 V and -1.68 V are belong to Zn-TCPP. The MQDs CV displaying in Fig. 2B that have only one reduction peak near -0.64 V
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in oxygen saturated (curve b) and the onset was potential about -0.26 V. Meanwhile, the MOF-545-Zn@MQDs CV (Fig. 2C) has three reduction peaks like to
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MOF-545-Zn, located at -0.64 V, -1.20 V and -1.68 V, respectively. Its onset potential was 0.08 V.
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The electrochemical impedance spectrum (EIS) showing in Fig. 2D, for the Rct of
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bare GCE (curve a), the Rct of MOF-545-Zn (curve b), the Rct MQDs (curve c) and Rct
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of MOF-545-Zn@MQDs was observed at 918 Ω, 418 Ω, 2102 Ω and 493 Ω,
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respectively.
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4 DISCUSSIONS
4.1 Synergetic effects between MOF-545-Zn and MQDs
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Based on the ECL response intensity were investigated, the MQDs can enhance the ECL response of the MOF-545-Zn, obviously. The MOF-545-Zn@MQDs ECL
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response intensity has been increased about three times as compared to MOF-545-Zn. Meanwhile, it has stable luminous performance that the ECL response intensity
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changes in a narrow rangeability and the relative standard deviation (RSD) of 3.7% (Fig. 1B). The O2 has been determined an important regent in ECL reaction [14], as compared to air saturated and the O2 saturated ECL response intensity increased from 3562 a.u. to 9247 a.u. and no ECL response can be seen in deoxygenated saturated, respectively. The ECL response intensity ratio with air saturated and O2 saturated was 9
1:4 that indicated the MOF-545-Zn@MQDs can enrich O2 in surface of substance. The different MQDs concentration effect with ECL intensity was shown in Fig. S2, it indicated that 10 mg mL-1 was most optimum concentration. The higher concentration of MQDs can depress ECL intensity because of the gas over enriched on the surface of hybrids material and resulting rejection of substance exchanged in the solution. The
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Photoluminescence emission spectrum (Fig. 1D) is showing that MQDs (curve a)
have a small peak at 488 nm [29] and the excitation wavelength was 397 nm.
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However, the MOF-545-Zn (curve b), MOF-545-Zn@MQDs (curve c) have the same
peaks at 466 nm, 660 nm, and 720 nm and it was like to Zn-TCPP PL emission peaks
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(curve d) which demonstrated the MOF-545-Zn and MOF-545-Zn@MQDs have the
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same luminophores that were Zn-TCPP. It’s indicated that MQDs haven’t obviously
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effect to MOF-545-Zn photoluminescence spectrum and the ECL spectrum of
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MOF-545-Zn in pH 7.4 HEPES solution and O2 saturated (inset Fig. 1D) indicated the system emission wavelength at 642 nm, research shows that was singlet oxygen [6,
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30].
The cyclic voltammetry (CV) was used to analyze the electrochemical change of the
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MQDs with MOF-545-Zn. The MOF-545-Zn CV curve shown in Fig. 2A, it
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displayed that the O2 reduction peak at -0.66 V and the onset potential at -0.26 V, the porphyrin reduction potential peaks at -1.20 V and -1.68 V. Previously reported, MQDs has excellent reduction properties [31, 32], the MQDs CV (Fig. 2B) shows the
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only O2 reduction peak, the reduction potential was -0.65 V and the onset potential was 0.26V. However, the MOF-545-Zn@MQDs CV (Fig. 2C) indicated that it has higher onset potential (in -0.09V) and reductive current (125.4 μA) as compared to pre-composite. From above experimentation the MQDs and MOF-545-Zn could produce a synergistic effect, made O2 more easily electron acceptor and been a 10
reduction. As compared to MOF-545-Zn, the MOF-545-Zn@MQDs has higher reduction peaks current at -1.20 V and 1.68 V, it belongs to Zn-TCPP. The EIS demonstrated the MQDs can markedly decrease impedance (Fig. 2D). From the above facts, the MQDs could promoted electron transformation and
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enriched O2 in substance surface that was made it easier to be reduced. It has synergistic interaction with MOF-545-Zn, therefore, the ECL response has been
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increased obviously (Fig. 1A)[33]. Based on the above discussion, the possible ECL mechanism is proposed with the following equation: O2 + e- → O•− 2
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O2
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•+ 2― Zn•+TCPP + O•− + 2 → Zn TCPP
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Zn2+TCPP + e- → Zn•+TCPP
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2 1O2 → ( 1O2 )∗2
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( 1O2 )∗2 → 2 3O2 + hυ (λ𝑒𝑥 = 642 nm)
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4.2 The structure of the MOF-545-Zn@MQDs SEM image (Fig. 3A) showing that MOF-545-Zn has the fiber-like structure and cross
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binding with each other, its diameter about 1μm (Inset Fig. 3A) and length exceed 200 μm. TEM (Fig. 3B) showing that MQDs diameter was about 1~2 nm and the absolute
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height centralized in 0.3 - 1.5 nm (Fig. 3C). The TEM image (Fig. 3D) of MOF-545-Zn@MQDs demonstrates MQDs dispersed over the surface of the MOF-545-Zn. It was determined by FT-IR spectrum and Raman Shift that demonstrated in Figure S1. As can be seen from UV-vis (Fig. S3A), the MoS2 (curve a) hasn’t absorbed peaks 11
between detection range, the MOF-545-Zn (curve b) has three peaks that respectively are 433 nm, 565 nm and 604 nm [15, 34]. The MOF-545-Zn@MQDs (curve c) has three peaks as like as MOF-545-Zn, its peak seat was not significantly changed but absorb intensity obviously increased that indicated the MQDs can be increased the solubility of MOF-545-Zn in DMF and not affect its internal structure, this effect
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made more Zn-TCPP exposed in solution and increased absorb intensity of
MOF-545-Zn. The powder XRD (Fig. S3B curve a) indicate the MQDs peaks occur at
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14.7° (002), its 2H MoS2 typical peaks[35]. Compared to MOF-545-Zn peaks (Fig.
3B curve b) the MOF-545-Zn@MQDs peaks (Fig. S2B curve c) have obviously
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changed[15] in 14.7° (002) peak has disappeared and 9.4° (200) peak has divided two
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peaks, this phenomenon indicated that MQDs was bond of MOD-545-Zn surface and
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changed its crystal structure.
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XPS was used to characterize the elemental composition and bonding configuration of the composite. In Fig. 4 are displayed the Mo3d, S2p, and C1s regions of the XPS
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acquired using as MQDs, MOF-545-Zn and MOF-545-Zn@MQDs samples displaying different valence ratio of Mo and S in MQDs and MOF-545-Zn@MQDs
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because of MQDs interacted with MOF-545-Zn. Further confirmed with the peaks
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belong to -COO- group has despaired in MOF-545-Zn@MQDs. More evidence of elemental analysis confirmed with the difference in the atomic ratio of Mo : S between MQDs and MOF-545-Zn@MQDs. The atomic ratio of Mo : S is increased
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from 1 : 2.38 in MQDs to 1 : 2.43 in MOF-545-Zn@MQDs, which is attributed to the decrease of the number of layers and the increase of the number of unsaturated sulfur atoms located at the external edge of MQDs[36]. Based on above analysis, a possible structure of MOF-545-Zn@MQDs was drawn in Scheme S1.
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4.3 Sample detection of CEA. Carcinoembryonic antigen (CEA) was a highly glycosylated protein and variously be used as a tumor marker for the clinical diagnosis of some types of cancer [37]. The immunosensors were employed to detect various concentrations CEA [38, 39]. In this
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work, we used functionalized MOF-545-Zn@MQDs by LA[28], it hasn’t affected the MOF-545-Zn@MQDs ECL response but also provided more numerous binding sites
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to anti CEA and the experimental indicated the LA concentration haven’t obviously
effect with ECL intensity (Fig. S4). As shown in Fig. 5A, multi-concentration CEA was detected by ECL and could be found that the ECL response intensity decreased
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with the increase of CEA concentration. Inset Fig. 5A showing the relationship of the
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ECL intensity and CEA concentration, it could be found that the logarithmic function
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correlation occurred between the ECL intensity decreased and CEA concentration[40].
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The linear range was obtained from 0.18 to1000 ng mL-1 and the detection limit was 0.45 pg mL-1. The key characteristics of different CEA immunosensors was compared
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the results are summarized in Table 1S. It indicates that our proposed immunosensor
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exhibits wider linear range. In addition, this proposed CEA immunosensor exhibits acceptable precision and reproducibility, with a relative standard deviation of 3.19%
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for 5 independent electrodes. Meanwhile,
in order to further prove the reliability of the immunosensors, the
recovery of different concentrations of CEA in serum sample was detected by
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standard addition method [39]. Serum real sample derived from the laboratory of hospital that CEA concentration reference value was 1.13 ng mL-1 (1), 4.94 ng mL-1 (2), 8.36 ng mL-1 (3), 21.88 ng mL-1 (4), 50.24 ng mL-1 (5), respectively. The real sample was prepared by adding 5 L above mentioned serum sample into 95L 13
standard CEA solution of 40 ng mL-1. The results are illustrated in Fig. 5B. The recovery is in the range of 123.6-128.1% with the RSDs varied from 2.0% to 4.4%, indicating the proposed CEA immunosensor has potential application for clinical detection of CEA in human serum samples.
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5 CONCLUSIONS
In this work, the MOF-545-Zn@MQDs was feasibly prepared with the ultrasonic
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method through the interaction between MQDs and MOF-545-Zn. The MQDs
increased ECL intensity of MOF-545-Zn because of the O2 enrichment and electron
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transformation have been enhanced. From the experimental results, new composite
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substance has more stable, higher ECL response and more easily functional. The
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biosensor system was constructed with this substance through LA functioned that
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acquired a better result. Accordingly, an enhanced ECL composite was synthesized and estabilished a novel ECL immunosensors system has huge potential in the various
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fields.
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■ ACKNOWLEDGMENT
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This research was supported by National Natural Science Foundation of China (Grant No.21675086) and a project founded by the priority academic program development of Jiangsu Higher Education Institutions (PAPD).
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Notes
The authors declare no competing financial interest. REFERENCE
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[1] Z. Liu, W. Qi, G. Xu, Recent advances in electrochemiluminescence, Chem. Soc. Rev., 44(2015) 3117-3142. [2] W. Miao, Electrogenerated chemiluminescence and its biorelated applications, Chem. Rev., 108(2008) 2506-2553. [3] Q.L. Zhu, Q. Xu, Metal-organic framework composites, Chem. Soc. Rev., 43(2014)
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5468-5512.
[4] L.H. Wee, Y. Li, K. Zhang, P. Davit, S. Bordiga, J. Jiang, I.F.J. Vankelecom, J.A.
SC R
Martens, Submicrometer-sized ZIF-71 filled organophilic membranes for improved bioethanol recovery: Mechanistic insights by monte carlo simulation and ftir
U
spectroscopy, Adv. Funct. Mater., 25(2015) 516-525.
N
[5] H.S. Cho, H.X. Deng, K. Miyasaka, Z.Y. Dong, M. Cho, A.V. Neimark, J.K. Kang,
A
O.M. Yaghi, O. Terasaki, Extra adsorption and adsorbate superlattice formation in
M
metal-organic frameworks, Nature, 527(2015) 503-U193. [6] A. Bolin, M.M. Richter, Coreactant electrogenerated chemiluminescence of
[7]
Y.
Xu,
ED
ruthenium porphyrins, Inorg. Chim. Acta, 362(2009) 1974-1976. X.B.
Yin,
X.W.
He,
Y.K.
Zhang,
Electrochemistry
and
PT
electrochemiluminescence from a redox-active metal-organic framework, Biosens.
CC E
Bioelectron., 68(2015) 197-203. [8] S. Zhu, X. Lin, P. Ran, Q. Xia, C. Yang, J. Ma, Y. Fu, A novel luminescence-functionalized metal-organic framework nanoflowers electrochemi
A
-luminesence sensor via "on-off" system, Biosens. Bioelectron., 91(2017) 436-440. [9] F.Y. Zhao, W.J. Li, A. Guo, L. Chang, Y. Li, W.J. Ruan, Zn(II) porphyrin based nano-/microscale metal-organic frameworks: Morphology dependent sensitization and photocatalytic oxathiolane deprotection, RSC Adv., 6(2016) 26199-26202. [10] Y. Bai, Y. Dou, L.H. Xie, W. Rutledge, J.R. Li, H.C. Zhou, Zr-based 15
metal-organic frameworks: Design, synthesis, structure, and applications, Chem. Soc. Rev., 45(2016) 2327-2367. [11] G.Y. Zhang, Y.H. Zhuang, D. Shan, G.F. Su, S. Cornier, X.J. Zhang, Zirconium-based porphyrinic metal-organic framework (PCN-222): Enhanced photoelectrochemical response and its application for label-free phosphoprotein
IP T
detection, Anal. Chem., 88(2016) 11207-11212.
[12] D. Yang, S.O. Odoh, J. Borycz, T.C. Wang, O.K. Farha, J.T. Hupp, C.J. Cramer,
SC R
L. Gagliardi, B.C. Gates, Tuning zr-6 metal-organic framework (MOF) nodes as catalyst supports: Site densities and electron-donor properties influence molecular
U
iridium complexes as ethylene conversion catalysts, Acs Catalysis, 6(2016) 235-247.
N
[13] C.W. Kung, T.H. Chang, L.Y. Chou, J.T. Hupp, O.K. Farha, K.C. Ho,
A
Porphyrin-based metal-organic framework thin films for electrochemical nitrite
M
detection, Electrochem. Commun., 58(2015) 51-56. [14] G.Y. Zhang, C. Cai, S. Cosnier, H.B. Zeng, X.J. Zhang, D. Shan,
ED
Zirconium-metalloporphyrin frameworks as a three-in-one platform possessing oxygen nanocage, electron media, and bonding site for electrochemiluminescence
PT
protein kinase activity assay, Nanoscale, 8(2016) 11649-11657.
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[15] W. Morris, B. Volosskiy, S. Demir, F. Gándara, P.L. McGrier, H. Furukawa, D. Cascio, J.F. Stoddart, O.M. Yaghi, Synthesis, structure, and metalation of two new highly porous zirconium metal–organic frameworks, Inorg. Chem., 51(2012)
A
6443-6445.
[16] N. Rathi, S. Rathi, I. Lee, J.W. Wang, M. Kang, D. Lim, M.A. Khan, Y. Lee, G.H. Kim, Reduction of persistent photoconductivity in a few-layer mos2 field-effect transistor by graphene oxide functionalization, RSC Adv., 6(2016) 23961-23967. [17] G. Liu, A.W. Robertson, M.J. Li, W.C.H. Kuo, M.T. Darby, M.H. Muhieddine, 16
Y.C. Lin, K. Suenaga, M. Stamatakis, J.H. Warner, Mos2 monolayer catalyst doped with isolated co atoms for the hydrodeoxygenation reaction, Nature Chem., 9(2017) 810-816. [18] S.X. Wu, Z.Y. Zeng, Q.Y. He, Z.J. Wang, S.J. Wang, Y.P. Du, Z.Y. Yin, X.P. Sun, W. Chen, H. Zhang, Electrochemically reduced single-layer MoS2 nanosheets:
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Characterization, properties, and sensing applications, Small, 8(2012) 2264-2270.
[19] X. Xiang, J.B. Shi, F.H. Huang, M.M. Zheng, Q.C. Deng, J. Xu, MoS2
SC R
nanosheet-based fluorescent biosensor for protein detection via terminal protection of
small-molecule-linked DNA and exonuclease iii-aided DNA recycling amplification,
U
Biosens. Bioelectron., 74(2015) 227-232.
N
[20] W.S. Zhang, P.P. Zhang, Z.Q. Su, G. Wei, Synthesis and sensor applications of
A
MoS2-based nanocomposites, Nanoscale, 7(2015) 18364-18378.
M
[21] T. Wang, K. Du, W. Liu, J. Zhang, M. Li, Electrochemical sensors based on molybdenum disulfide nanomaterials, Electroanalysis, 27(2015) 2091-2097.
ED
[22] B.R. Garrett, S.M. Polen, M. Pimplikar, C.M. Hadad, Y. Wu, Anion-redox mechanism of MoO(S2)2(2,2’-bipyridine) for electrocatalytic hydrogen production, J.
PT
Am. Chem. Soc., 139(2017) 4342.
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[23] W. Gu, Y.H. Yan, C.L. Zhang, C.P. Ding, Y.Z. Xian, One-step synthesis of water-soluble MoS2 quantum dots via a hydrothermal method as a fluorescent probe for hyaluronidase detection, Acs Appl. Mater. Interfaces, 8(2016) 11272-11279.
A
[24] B. Zhao, C. Shang, N. Qi, Z.Y. Chen, Z.Q. Chen, Stability of defects in monolayer MoS2 and their interaction with O2 molecule: A first-principles study, Appl. Surf. Sci., 412(2017) 385-393. [25] Y. Tong, Y. Liu, Y. Zhao, J. Thong, D.S.H. Chan, C. Zhu, Selectivity of MoS2 gas sensors based on a time constant spectrum method, Sens. Actuators, A:Phy., 255(2017) 17
28-33. [26] P. Joensen, R.F. Frindt, S.R. Morrison, Single-layer MoS2, Mater. Res. Bull., 21(1986) 457-461. [27] S. Xu, D. Li, P. Wu, One-pot, facile, and versatile synthesis of monolayer MoS2/
evolution reaction, Adv. Funct. Mater., 25(2015) 1127-1136.
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WS2 quantum dots as bioimaging probes and efficient electrocatalysts for hydrogen
[28] M. Jeong, S. Kim, S.-Y. Ju, Preparation and characterization of a covalent
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edge-functionalized lipoic acid–MoS2 conjugate, RSC Adv., 6(2016) 36248-36255.
[29] H. Huang, C. Du, H. Shi, X. Feng, J. Li, Y. Tan, W. Song, Water-soluble
U
monolayer molybdenum disulfide quantum dots with upconversion fluorescence, Part.
N
Part. Syst. Char., 32(2015) 72-79.
A
[30] W.R. Cai, G.Y. Zhang, K.K. Lu, H.B. Zeng, S. Cosnier, X.J. Zhang, D. Shan,
M
Enhanced electrochemiluminescence of one-dimensional self-assembled porphyrin hexagonal nanoprisms, Acs Appl. Mater. Interfaces, 9(2017) 20904-20912.
ED
[31] A.B. Laursen, S. Kegnæs, S. Dahl, I. Chorkendorff, Molybdenum sulfides—efficient and viable materials for electro - and photoelectrocatalytic
PT
hydrogen evolution, Energ. Environ. Sci., 5(2012) 5577.
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[32] M.V. Bollinger, J.V. Lauritsen, K.W. Jacobsen, J.K. Norskov, S. Helveg, F. Besenbacher, One-dimensional metallic edge states in MoS2, Phys. Rev. Lett., 87(2001) 196803.
A
[33] Y. Li, H. Wang, L. Xie, Y. Liang, G. Hong, H. Dai, MoS2 nanoparticles grown on graphene: An advanced catalyst for the hydrogen evolution reaction, J. Am. Chem. Soc., 133(2011) 7296-7299. [34] X.B. Li, Y.J. Gao, H.L. Wu, Y. Wang, Q. Guo, M.Y. Huang, B. Chen, C.H. Tung, L.Z. Wu, Assembling metallic 1T- MoS2 nanosheets with inorganic-ligand stabilized 18
quantum dots for exceptional solar hydrogen evolution, Chem. Commun., 53(2017) 5606-5609 [35] R.M. Clark, B.J. Carey, T. Daeneke, P. Atkin, M. Bhaskaran, K. Latham, I.S. Cole, K. Kalantar-Zadeh, Two-step synthesis of luminescent MoS2-ZnS hybrid quantum dots, Nanoscale, 7(2015) 16763-16772.
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[36] C. Ma, H. Zhu, J. Zhou, Z. Cui, T. Liu, Y. Wang, Y. Wang, Z. Zou, Confinement
effect of monolayer MoS2 quantum dots on conjugated polyimide and promotion of
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solar-driven photocatalytic hydrogen generation, Dalton Trans, 46(2017) 3877-3886.
[37] P. Thomas, A. Gangopadhyay, S.G. Jr, C. Andrews, H. Nakazato, S. Oikawa, J.M.
U
Jessup, The effect of transfection of the cea gene on the metastatic behavior of the
N
human colorectal cancer cell line MIP-101, Cancer Lett., 92(1995) 59-63.
A
[38] N. Van Anh, H. Van Trung, B.Q. Tien, N.H. Binh, C.H. Ha, N. Le Huy, N.T. Loc,
M
V.T. Thu, T.D. Lam, Development of a pmma electrochemical microfluidic device for carcinoembryonic antigen detection, J. Electron. Mater., 45(2016) 2455-2462.
electrochemical
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[39] L. Tian, L. Liu, Y. Li, Q. Wei, W. Cao, Ultrasensitive sandwich-type immunosensor
based
on
trimetallic
nanocomposite
signal
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30849.
PT
amplification strategy for the ultrasensitive detection of CEA, Sci. Rep., 6(2016)
[40] Q. Liu, Y. Yang, X.P. Liu, Y.P. Wei, C.J. Mao, J.S. Chen, H.L. Niu, J.M. Song, S.Y. Zhang, B.K. Jin, A facile in situ synthesis of MIL-101-CdSe nanocomposites for
A
ultrasensitive electrochemiluminescence detection of carcinoembryonic antigen, Sens. Actuators, B: Chem., 242(2017) 1073-1078.
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Author Biographies Wenli Xin is currently studying for degree of MS in School of Environmental and Biological Engineering, Nanjing University
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of Science & Technology, PR China.
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Lianfu Jiang is currently studying for degree of Ph.D in MIIT Key Laboratory of Advanced Display Materials and Devices,
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Nanjing University of Science and Technology, PR china.
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Liping Zong is currently studying for degree of MS in School of
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Environmental and Biological Engineering, Nanjing University
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of Science & Technology, PR China.
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Haibo Zeng is presently employed as a professor in MIIT Key Laboratory of Advanced Display Materials and Devices, Nanjing University of Science and Technology, PR china. He received her MS in Applied mathematics from Hubei University, China in 2003, and her PhD in electrochemistry from Institute of Biophysics, Chinese Academy of Sciences in
2006. He current fields of interest include research on new display and special sensing 20
materials. GuoFang Shu is presently employed as a dorctor in Clinical laboratory
of
Zhongda
Hospital,
Affiliated
to
Southeast University. He received his MS in Southeast University, China in 2013, and he was associate chief
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technician in Clinical laboratory of Zhongda Hospital form 2015 to now.
Department
of
Biotechnology
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Robert S. Marks is presently employed as a professor in Engineering,
Ben-Gurion
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University of the Negev, Beer-Sheva, Israel. He received his
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MS Physiology and Cell Biology from University of California,
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Santa Barbara, USA in 1987, and PhD Chemical Immunology,
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The Weizmann Institute of Science, Rehovot, Israel in 1992. The main focus remains diagnostics (mainly biosensors), with the latest novel technology,
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electrolateral flow immunosensor.
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Dan Shan is presently employed as a professor in School of Environmental
and
Biological
Engineering,
Nanjing
University of Science & Technology, PR China. She received her MS in physical chemistry from Yangzhou University, China in 2001, and her PhD in electrochemistry from Joseph
Fourier University of Grenoble (France) in 2004. She worked at School of Chemistry & Chemical Engineering, Yangzhou University, PR China from 2004 to 2011. Her current fields of interest include biosensor, interfacial electrochemistry and 21
electroconductive polymer. Xue-Ji Zhang is a professor and Dean in school of chemistry and biological engineering, University of Science and Technology Beijing, PR China. He received his PhD in electrochemistry from Wu Han University, PR China (1989). current
fields
of
interest
include
bio-analysis,
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His
electrochemical sensors and biosensors, microelectrodes,
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ultramicroelectrodes and nanoelectrodes, nanosensors, free radical sensors.
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Figure captions
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Figure 1 (A) ECL-potential curves of GCE/ MQDs (a), GCE/MOF-545-Zn (b) and GCE/MOF-545-Zn@MQDs (c) O2-saturated in pH 7.4 HEPES solution during a
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continuous potential scan between −1.8 and 0 V, scan rate: 100 mV s−1. (B) ECL–time response of GCE/MOF-545-Zn@MQDs recorded in O2-saturated pH 7.4 HEPES
solution during a continuous potential scan between −1.8 and 0 V, scan rate: 100 mV
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s−1. (C) ECL-potential curve of GCE/MOF-545@MQDs in N2-saturated (a),
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Air-saturated (b) and O2-saturated (c) in pH 7.4 HEPES solution. (D)
and
Zn-TCPP
(d),
in
ethanol.
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(c)
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Photoluminescence spectrum of MQDs (a), MOF-545-Zn (b), MOF-545-Zn@MQDs Inset
D:
ECL
spectrum
of
GCE/MOF-545-Zn@MQDs in the O2-saturated pH 7.4 HEPES solution biased at
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−1.68 V.
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Figure 2 CVs of (A) GCE/MOF-545-Zn, (B) GCE/MQDs, (C) GCE/MOF-545-Zn@ MQDs in the N2-saturated (a) and O2-saturated (b) pH 7.4 HEPES solution during a
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continuous potential scan between −1.8 and 0 V, scan rate: 100 mV s−1. (D) EIS of bare GCE (a), GCE/MOF-545-Zn (b), GCE/ MQDs (c), GCE/MOF-545-Zn@MQDs 4−/3−
.
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(d) in the in 0.1 M KCl solution containing 5 mM Fe(CN)6
Figure 3 (A) SEM image of MOF-545-Zn. Inset A: Enlarged SEM image of MOF-545-Zn. (B) TEM image of MQDs. (C) AFM image of MQDs deposited on a glass substrate (a region of small coverage is shown to determine the thickness of the film), Insect B: Height profile of the film along the line depicted in (C). (D) TEM 23
image of Zn-545-Zn@MQDs. Figure 4 XPS of MQDs Mo3d (A), S2p (C), MOF-545-Zn C1s (E) and MOF-545-Zn@MQDs Mo3d (B), S2p (D), C1s (F). Figure 5 (A) ECL–potential curves of the modified electrode at different
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concentrations of CEA (a–h: 0, 0.0001, 0.002, 0.01, 0.04, 0.1, 0.4, 1.0 μg/mL). Inset A: The calibration plots of ECL peak intensity versus the logarithm of CEA
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concentration. Error bar =RSD (n=5). (B) Addition 5 μL real sample that CEA concentration was 1.13 ng/mL (1), 4.94 ng/mL (2), 8.36 ng/mL (3), 21.88 ng/mL (4), 50.24 ng/mL (5)1 in 95 μL test sample that concentration was 40 ng/mL CEA. (Red:
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theoretical value; blue: real value). Error bar =RSD (n=5).
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Scheme 1 Schematic illustration for the ECL mechanism of singlet oxygen and the
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construction of CEA immunosensor based on GCE/MOF-545-Zn@ MQDs
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Figure 1
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Figure 2
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Figure 3
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Figure 4
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Figure 5
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Scheme 1
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S0925-4005(18)31195-X https://doi.org/10.1016/j.snb.2018.06.090 SNB 24927
To appear in:
Sensors and Actuators B
Received date: Revised date: Accepted date:
4-4-2018 15-6-2018 19-6-2018
Please cite this article as: Xin W-Li, Jiang L-Fu, Zong L-Ping, Zeng H-Bo, Shu G-Fang, Marks R, Zhang X-ji, Shan D, MoS2 quantum dots-combined zirconium-metalloporphyrin frameworks: Synergistic effect on electron transfer and application for bioassay, Sensors and Actuators: B. Chemical (2018), https://doi.org/10.1016/j.snb.2018.06.090 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Ms.Ref.No.: SNB-D-18-01460
MoS2 quantum dots-combined zirconium-metalloporphyrin frameworks: Synergistic effect on electron transfer and
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application for bioassay Wen-Li Xin,† Lian-Fu Jiang,† Li-Ping Zong,† Hai-Bo Zeng,†* Guo-Fang Shu, ‡
†MIIT
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Robert Marks,§ Xue-ji Zhang,¿ Dan Shan†*
Key Laboratory of Advanced Display Materials and Devices, School of
Environmental and Biological Engineering, Nanjing University of Science and
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of Clinical Laboratory, Zhongda Hospital, Affiliated to Southeast University,
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‡Centre
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Nanjing 210009, China
Department of Biotechnology Engineering, Ben-Gurion University of the Negev,
Beer-Sheva, Israel.
School of chemistry and biological engineering, University of Science and
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¿
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§
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Technology, Nanjing 210094, China
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Technology Beijing, Beijing 100083, China
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*Corresponding author: Email: [email protected] (D. Shan) [email protected] (H.B. Zeng) Fax: 0086-25-84303107 1
The ECL emission of singlet oxygen in aqueous media was originated from
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Highlights
successive electro-reduction of zinc porphyrin in MOF-545-Zn as electron media
MOF-545-Zn could be functionalized with the 2D-MoS2(MQDs) and enhanced
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reacting with O2 in the 3D nanocage.
Modified by lipoic acid, the as-synthesized MOF-545-Zn@MQDs was further
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ECL intensity was obtained due to the synergetic effect of the O2 electrocatalysis.
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used as signal amplifying probes for ultrasensitive ECL CEA assay.
ABSTRACT
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In this study, 2D-MoS2 quantum dots (MQDs) were combined with the zirconium based porphyrinic metal-organic framework (MOF-545-Zn) through simple ultrasonic method for the purpose of the enhanced electrochemiluminescence (ECL). In addition, electrochemiluminescence (ECL), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed to investigate the synergistic effect on 2
electron transfer of the composite. MQD loading with confined orientation on the surface of MOF-545-Zn was confirmed by morphology and spectroscopy. Moreover, from hybrids material, the higher ECL intensity was received. MOF-545-Zn@MQDs was functionalized by alpha lipoic acid (LA) and was further applied to develop a
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novel ECL immunosensors for carcinoembryonic antigen (CEA).
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Keywords: electrochemiluminescence, metal-organic framework, 2D-MoS2 quantum dots, immunoassay
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1 INTRODUCTION
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The electrochemiluminescence (ECL) is a powerful analytical tool and has been
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widely applied in multiple fields[1]. In most cases, the ECL system is composed of
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luminophore (electrochemical process) and co-reactant (chemical reaction) [2].
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Recently, the electrochemical studies utilized metal complexes, luminol, and nanomaterials as ECL luminophore. The core issues of ECL are response intensity and
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co-reaction efficiency. New ECL system has attracted much attention due to the high efficiency and excellent stabilities [1]. Metal-organic frameworks (MOFs) are
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multifunctional materials which consist of metal moieties and organic ligand bridges. Because of chemical functionalities, tunable pore sizes, and large surface areas, MOFs
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have been widely used in gas storage/separation, catalysis, sensing, and drug delivery[3-5]. MOFs, made metal porphyrin as organic ligand, have also been reported to act as ECL luminophores [6-9]. The Zr-based MOFs have been synthesized variously[9-12], thereinto, the MOF-525-Zn can be served as an ECL luminophore because of it has excellent ECL response and stability[13]. Furthermore, 3
our previous work utilized MOF-525-Zn established a new ECL systems which combined with MOF-525-Zn and O2, was successfully used in biosensor[11, 14]. However, in this system, the Zn-TCPP numbers in the MOF-525-Zn surface are less than that in the MOF-545-Zn surface[15]. Therefore, the MOF-545-Zn was used to synthesized composites in this work.
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Moreover, the electron transfer efficiency is an important part in ECL progress， although, enhanced electron transfer efficiency was an important way to achieve
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higher ECL intensity. The MoS2 was a typical two-dimensional material, have lately attracted much attention as an energy acceptor in resonance energy transfer because of
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their special properties in nanoelectronics, optoelectronics, and energy harvesting
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properties [16, 17]. the MoS2 nanosheets have multimethod to prepare, such as
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micromechanical cleavage, lithium interaction, liquid exfoliation, hydrothermal
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reaction, chemical reaction [18-22]. Moreover, while the size of MoS2 was controlled to be less than 10 nm, MoS2 quantum dots (MQDs) has been synthesized. The MQDs
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possess unique optical and electronic properties and are potentially applicable in fluorescence sensing, catalysis, bioimaging because of quantum confinement and
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edge effect[23]. The MQDs has excellent gas absorb property and be used to gas
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sensor [24, 25]. Based on the MQDs can catalytic O2 reaction and absorbed, in the other hand the O2 was better co-reactant in ECL process of MOF-545-Zn, composites the MQDs with MOF-545-Zn could received a composite which have higher ECL
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response.
2 EXPERIMENTAL 2.1 Materials and Reagents Zirconium (IV) chloride, N, N-dimethylformamide (DMF), sodium salt (HEPES) 4
were purchased from Sigma-Aldrich Chemical Co., Ltd. (Shanghai, China). Zn-meso-tetra (4-carboxyphenyl) porphyrin (Zn-TCPP) was bought from J&K Scientific Ltd. (Shanghai, China). All other reagents were of analytical grade and were used without further purification. Ultrapure water obtained from a Millipore water purification system (≥18 MΩ, Milli-Q, Millipore) was used as the water source
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throughout the work. The 10 mM pH 7.4 HEPES containing 0.3 M KCl solution was employed as an aqueous electrolyte solution for photoelectrochemical and
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electrochemical measurements. 2.2 Characterization
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ECL measurements were carried out on an MPI-E multifunctional electrochemical
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and chemiluminescent analytical system (Xi’an Remex Analytical Instrument Co., Ltd,
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China). Photoluminescence (PL) was recorded by an Edinburgh FLS920 fluorescence
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spectrometer (Livingston, UK). All electrochemical measurements were carried out
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on a CHI 660D (Chenhua, China) at room temperature. All electrochemical studies were performed with a conventional three electrode system. The Ag/AgCl electrode
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and Pt wire electrode was used as reference and counter electrode, respectively. A modified glassy carbon (GCE, 3 mm in diameter) was used as working electrode.
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Before modification, the GCE was polished carefully with 0.3 and 0.05 m of α-Al2O3 powder, subsequently, washed with ethanol and ultrapure water in proper
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order, blow dry with N2 and packaging electrode with TOAB when accomplish modified. Electrochemical impedance spectroscopy (EIS) measurements were carried out using an Autolab PGSTAT30 (Eco chemie, The Netherlands) controlled by NOVA 2.0 software. The morphology was investigated with a XL-30E scanning electron microscope (SEM). Powder X-ray diffraction patterns (PXRD) were recorded on a 5
Bruker D8-Focus Bragg Brentano X-ray Powder diffract meter equipped with a Cu sealed tube (λ = 1.54178 Å) at room temperature. The ultraviolet absorption spectra were measured by UV-vis spectrophotometry (UV-3600, Shimadzu, Japan). The X-ray photoelectron spectroscopy (XPS) experiments were carried out on K-Alpha (Thermo Fisher Scientific Co., USA). Deoxygenated deionized water obtained by
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bubbling N2 to remove O2 from the water.
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2.3 Preparation of MOF-545-Zn@MQDs composites
The MOF-545-Zn was synthesized according to the previously reported hydrothermal method[15]. Zirconyl chloride octahydrate (37.5 mg) was added to 10 mL DMF and
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sonicated for 0.5 hours. Following sonication, Zn (II) meso-tetra (4-carboxyphenyl)
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porphyrin (6.5 mg) was added to the mixed solution. After a further ten minutes of
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sonication, 7 mL of formic acid was added. The mixture was placed into 20 mL
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scintillation vials and heated at 130 °C for three days. The samples were collected by
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filtration and washed with DMF. The DMF was then replaced with acetone over a five day period. Finally, the volatile acetone was removed by heating at 120 °C under
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vacuum for 48 hours. In addition, the MQDs were obtained via two step method, the n-butyl lithium intercalation[26] and ultrasonic liquid exfoliationc[27]. Firstly, in
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glove box, 0.8 g bulk MoS2 was suspended in 15 mL n-Butyl lithium (n-Hexane) and transferred to a 50 mL Teflon-lined stainless steel autoclave then kept at 90 oC for 12 hours. Following, the mixture was washed with n-Hexane in glove box and then
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solvent was removed by heating at 30 oC under vacuum for 48 h. Next, decentralized solid in deoxygenated deionized water and probe sonicated for 2 h, the resulting mixture was centrifuged at 4000 rpm for 60 minutes, to remove sediment solid and obtained MQDs suspension. 6
The MOF-545-Zn@MQDs composite was obtained with ultrasonic compositeness. Briefly, mixed isovolumetric 10 mg L-1 MQDs and 30 mg mL-1 MOF-545-Zn, the MOF-545-Zn@MQDs suspension was obtained after the mixture ultrasonicated for 0.5 hours.
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2.4 Fabrication of CEA biosensor The procedure for the preparation of ECL immunosensor for CEA was illustrated in
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Scheme 1. Initially, MOF-545-Zn@MQDs modified electrode was obtained by coating GCE with 10 L of MOF-545-Zn@MQDs mixture (20 mg mL-1) and dried
under ambient temperature. For the purpose of biomodification, 10 L LA (5 mg L-1)
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was pipetted onto the MOF-545-Zn@MQDs modified electrode and kept for 30
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min[28]. The above prepared electrode was further activated by 20 mg mL-1 of
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EDC/NHS(c (EDC) =20 mg mL-1, c (NHS) =10 mg mL-1) for 0.5 hours. Subsequently,
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the above electrode was incubated at 4 oC with 10 L of CEACAM5 ( one of the
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antibodies of CEA.) solution (0.01 mg mL-1, 0.01 M PBS, PH 7.4) for 12 hours. Finally, 10 μL of 1 wt% BSA as a blocking reagent was dropped onto the surface of
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electrode for 1 hours to eliminate nonspecific binding effects.
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3 RESULTS
3.1 ECL Investigation
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Practically, MQDs were combined with MOF-545-Zn via a simple ultrasonic method. The ECL behavior of the obtained MOF-545-Zn@MQDs was investigated. GCE/MOF-545-Zn@MQDs
was
feasibly prepared
by
casting
10
L of
MOF-545-Zn@MQDs solution (20 mg mL1) on the surface of GCE and dried at ambient temperature. GCE/MOF-545-Zn and GCE/MQDs were fabricated following 7
the same procedure and used as a control. Fig. 1 showing the ECL files of the modified electrode in HEPES (10 mM) buffer solution. In the O2-saturated environment, no obvious ECL signal can be observed at GCE/MQDs (curve a of Fig. 1A). Moreover, for the case of GCE/ MOF-545-Zn and GCE/MOF-545-Zn@MQDs, the maximum ECL response intensity can be found at 3088 a.u. and 9177 a.u., (curve
b,
c
of
Fig.
1A).
The
ECL
responses
of
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respectively,
GCE/MOF-545-Zn@MQDs are illustrated in Fig. 1B, which was obtained during a
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continuous potential scan, showing constant and stable signals and the relative
standard deviation (RSD) was just 3.7 %, respectively. The effect of O2 on the ECL
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response of GCE/MOF-545-Zn@MQDs was also evaluated (Fig. 1C) and no signal
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response was observed in the deoxygenated environment (curve a of Fig. 1C). ECL
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response intensity for the saturated air and O2 can be observed at 3562 a.u. and 9294
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a.u.(curve b, c of Figure 1C).
In addition, the photoluminescence properties of the composites were investigated.
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The photoluminescence spectra of MQDs exhibits a peak at 488 nm (curve a of Fig. 1D) and the photoluminescence emission peaks of the MOF-545-Zn@MQDs,
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MOF-545-Zn, and Zn-TCPP are expressing in curve b, c, and d of Fig. 1D. The ECL
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spectrum of GCE/MOF-545-Zn@MQDs in the O2-saturated aqueous electrolyte solution biased at -1.68 V was performed that ECL emission occurred in the range of 400-700 nm and the maximum wavelength is at 642 nm (inset of Fig. 1D).
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3.2 Electrochemical Investigation Cyclic voltammetry (CV) was used to analyze electrochemical behaviors of the MOF-545-Zn, MQDs and MOF-545-Zn@MQDs in HEPES (10 mM) buffer solution system, the continuous potential scan rate was between -1.8 V to - 0 V and 100 mV s-1. 8
As the MOF-545-Zn CV (Fig. 2A) in the deoxygenated environment (curve a), a reduction peak can be observed. Meanwhile in saturated oxygen environment (curve b), reduction peak of the dissolved oxygen was found at -0.65 V and onset potential near -0.26 V, other two reduction peaks -1.20 V and -1.68 V are belong to Zn-TCPP. The MQDs CV displaying in Fig. 2B that have only one reduction peak near -0.64 V
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in oxygen saturated (curve b) and the onset was potential about -0.26 V. Meanwhile, the MOF-545-Zn@MQDs CV (Fig. 2C) has three reduction peaks like to
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MOF-545-Zn, located at -0.64 V, -1.20 V and -1.68 V, respectively. Its onset potential was 0.08 V.
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The electrochemical impedance spectrum (EIS) showing in Fig. 2D, for the Rct of
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bare GCE (curve a), the Rct of MOF-545-Zn (curve b), the Rct MQDs (curve c) and Rct
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of MOF-545-Zn@MQDs was observed at 918 Ω, 418 Ω, 2102 Ω and 493 Ω,
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respectively.
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4 DISCUSSIONS
4.1 Synergetic effects between MOF-545-Zn and MQDs
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Based on the ECL response intensity were investigated, the MQDs can enhance the ECL response of the MOF-545-Zn, obviously. The MOF-545-Zn@MQDs ECL
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response intensity has been increased about three times as compared to MOF-545-Zn. Meanwhile, it has stable luminous performance that the ECL response intensity
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changes in a narrow rangeability and the relative standard deviation (RSD) of 3.7% (Fig. 1B). The O2 has been determined an important regent in ECL reaction [14], as compared to air saturated and the O2 saturated ECL response intensity increased from 3562 a.u. to 9247 a.u. and no ECL response can be seen in deoxygenated saturated, respectively. The ECL response intensity ratio with air saturated and O2 saturated was 9
1:4 that indicated the MOF-545-Zn@MQDs can enrich O2 in surface of substance. The different MQDs concentration effect with ECL intensity was shown in Fig. S2, it indicated that 10 mg mL-1 was most optimum concentration. The higher concentration of MQDs can depress ECL intensity because of the gas over enriched on the surface of hybrids material and resulting rejection of substance exchanged in the solution. The
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Photoluminescence emission spectrum (Fig. 1D) is showing that MQDs (curve a)
have a small peak at 488 nm [29] and the excitation wavelength was 397 nm.
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However, the MOF-545-Zn (curve b), MOF-545-Zn@MQDs (curve c) have the same
peaks at 466 nm, 660 nm, and 720 nm and it was like to Zn-TCPP PL emission peaks
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(curve d) which demonstrated the MOF-545-Zn and MOF-545-Zn@MQDs have the
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same luminophores that were Zn-TCPP. It’s indicated that MQDs haven’t obviously
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effect to MOF-545-Zn photoluminescence spectrum and the ECL spectrum of
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MOF-545-Zn in pH 7.4 HEPES solution and O2 saturated (inset Fig. 1D) indicated the system emission wavelength at 642 nm, research shows that was singlet oxygen [6,
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30].
The cyclic voltammetry (CV) was used to analyze the electrochemical change of the
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MQDs with MOF-545-Zn. The MOF-545-Zn CV curve shown in Fig. 2A, it
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displayed that the O2 reduction peak at -0.66 V and the onset potential at -0.26 V, the porphyrin reduction potential peaks at -1.20 V and -1.68 V. Previously reported, MQDs has excellent reduction properties [31, 32], the MQDs CV (Fig. 2B) shows the
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only O2 reduction peak, the reduction potential was -0.65 V and the onset potential was 0.26V. However, the MOF-545-Zn@MQDs CV (Fig. 2C) indicated that it has higher onset potential (in -0.09V) and reductive current (125.4 μA) as compared to pre-composite. From above experimentation the MQDs and MOF-545-Zn could produce a synergistic effect, made O2 more easily electron acceptor and been a 10
reduction. As compared to MOF-545-Zn, the MOF-545-Zn@MQDs has higher reduction peaks current at -1.20 V and 1.68 V, it belongs to Zn-TCPP. The EIS demonstrated the MQDs can markedly decrease impedance (Fig. 2D). From the above facts, the MQDs could promoted electron transformation and
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enriched O2 in substance surface that was made it easier to be reduced. It has synergistic interaction with MOF-545-Zn, therefore, the ECL response has been
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increased obviously (Fig. 1A)[33]. Based on the above discussion, the possible ECL mechanism is proposed with the following equation: O2 + e- → O•− 2
1
O2
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•+ 2― Zn•+TCPP + O•− + 2 → Zn TCPP
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Zn2+TCPP + e- → Zn•+TCPP
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2 1O2 → ( 1O2 )∗2
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( 1O2 )∗2 → 2 3O2 + hυ (λ𝑒𝑥 = 642 nm)
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4.2 The structure of the MOF-545-Zn@MQDs SEM image (Fig. 3A) showing that MOF-545-Zn has the fiber-like structure and cross
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binding with each other, its diameter about 1μm (Inset Fig. 3A) and length exceed 200 μm. TEM (Fig. 3B) showing that MQDs diameter was about 1~2 nm and the absolute
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height centralized in 0.3 - 1.5 nm (Fig. 3C). The TEM image (Fig. 3D) of MOF-545-Zn@MQDs demonstrates MQDs dispersed over the surface of the MOF-545-Zn. It was determined by FT-IR spectrum and Raman Shift that demonstrated in Figure S1. As can be seen from UV-vis (Fig. S3A), the MoS2 (curve a) hasn’t absorbed peaks 11
between detection range, the MOF-545-Zn (curve b) has three peaks that respectively are 433 nm, 565 nm and 604 nm [15, 34]. The MOF-545-Zn@MQDs (curve c) has three peaks as like as MOF-545-Zn, its peak seat was not significantly changed but absorb intensity obviously increased that indicated the MQDs can be increased the solubility of MOF-545-Zn in DMF and not affect its internal structure, this effect
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made more Zn-TCPP exposed in solution and increased absorb intensity of
MOF-545-Zn. The powder XRD (Fig. S3B curve a) indicate the MQDs peaks occur at
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14.7° (002), its 2H MoS2 typical peaks[35]. Compared to MOF-545-Zn peaks (Fig.
3B curve b) the MOF-545-Zn@MQDs peaks (Fig. S2B curve c) have obviously
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changed[15] in 14.7° (002) peak has disappeared and 9.4° (200) peak has divided two
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peaks, this phenomenon indicated that MQDs was bond of MOD-545-Zn surface and
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changed its crystal structure.
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XPS was used to characterize the elemental composition and bonding configuration of the composite. In Fig. 4 are displayed the Mo3d, S2p, and C1s regions of the XPS
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acquired using as MQDs, MOF-545-Zn and MOF-545-Zn@MQDs samples displaying different valence ratio of Mo and S in MQDs and MOF-545-Zn@MQDs
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because of MQDs interacted with MOF-545-Zn. Further confirmed with the peaks
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belong to -COO- group has despaired in MOF-545-Zn@MQDs. More evidence of elemental analysis confirmed with the difference in the atomic ratio of Mo : S between MQDs and MOF-545-Zn@MQDs. The atomic ratio of Mo : S is increased
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from 1 : 2.38 in MQDs to 1 : 2.43 in MOF-545-Zn@MQDs, which is attributed to the decrease of the number of layers and the increase of the number of unsaturated sulfur atoms located at the external edge of MQDs[36]. Based on above analysis, a possible structure of MOF-545-Zn@MQDs was drawn in Scheme S1.
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4.3 Sample detection of CEA. Carcinoembryonic antigen (CEA) was a highly glycosylated protein and variously be used as a tumor marker for the clinical diagnosis of some types of cancer [37]. The immunosensors were employed to detect various concentrations CEA [38, 39]. In this
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work, we used functionalized MOF-545-Zn@MQDs by LA[28], it hasn’t affected the MOF-545-Zn@MQDs ECL response but also provided more numerous binding sites
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to anti CEA and the experimental indicated the LA concentration haven’t obviously
effect with ECL intensity (Fig. S4). As shown in Fig. 5A, multi-concentration CEA was detected by ECL and could be found that the ECL response intensity decreased
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with the increase of CEA concentration. Inset Fig. 5A showing the relationship of the
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ECL intensity and CEA concentration, it could be found that the logarithmic function
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correlation occurred between the ECL intensity decreased and CEA concentration[40].
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The linear range was obtained from 0.18 to1000 ng mL-1 and the detection limit was 0.45 pg mL-1. The key characteristics of different CEA immunosensors was compared
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the results are summarized in Table 1S. It indicates that our proposed immunosensor
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exhibits wider linear range. In addition, this proposed CEA immunosensor exhibits acceptable precision and reproducibility, with a relative standard deviation of 3.19%
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for 5 independent electrodes. Meanwhile,
in order to further prove the reliability of the immunosensors, the
recovery of different concentrations of CEA in serum sample was detected by
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standard addition method [39]. Serum real sample derived from the laboratory of hospital that CEA concentration reference value was 1.13 ng mL-1 (1), 4.94 ng mL-1 (2), 8.36 ng mL-1 (3), 21.88 ng mL-1 (4), 50.24 ng mL-1 (5), respectively. The real sample was prepared by adding 5 L above mentioned serum sample into 95L 13
standard CEA solution of 40 ng mL-1. The results are illustrated in Fig. 5B. The recovery is in the range of 123.6-128.1% with the RSDs varied from 2.0% to 4.4%, indicating the proposed CEA immunosensor has potential application for clinical detection of CEA in human serum samples.
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5 CONCLUSIONS
In this work, the MOF-545-Zn@MQDs was feasibly prepared with the ultrasonic
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method through the interaction between MQDs and MOF-545-Zn. The MQDs
increased ECL intensity of MOF-545-Zn because of the O2 enrichment and electron
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transformation have been enhanced. From the experimental results, new composite
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substance has more stable, higher ECL response and more easily functional. The
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biosensor system was constructed with this substance through LA functioned that
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acquired a better result. Accordingly, an enhanced ECL composite was synthesized and estabilished a novel ECL immunosensors system has huge potential in the various
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fields.
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■ ACKNOWLEDGMENT
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This research was supported by National Natural Science Foundation of China (Grant No.21675086) and a project founded by the priority academic program development of Jiangsu Higher Education Institutions (PAPD).
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Notes
The authors declare no competing financial interest. REFERENCE
14
[1] Z. Liu, W. Qi, G. Xu, Recent advances in electrochemiluminescence, Chem. Soc. Rev., 44(2015) 3117-3142. [2] W. Miao, Electrogenerated chemiluminescence and its biorelated applications, Chem. Rev., 108(2008) 2506-2553. [3] Q.L. Zhu, Q. Xu, Metal-organic framework composites, Chem. Soc. Rev., 43(2014)
IP T
5468-5512.
[4] L.H. Wee, Y. Li, K. Zhang, P. Davit, S. Bordiga, J. Jiang, I.F.J. Vankelecom, J.A.
SC R
Martens, Submicrometer-sized ZIF-71 filled organophilic membranes for improved bioethanol recovery: Mechanistic insights by monte carlo simulation and ftir
U
spectroscopy, Adv. Funct. Mater., 25(2015) 516-525.
N
[5] H.S. Cho, H.X. Deng, K. Miyasaka, Z.Y. Dong, M. Cho, A.V. Neimark, J.K. Kang,
A
O.M. Yaghi, O. Terasaki, Extra adsorption and adsorbate superlattice formation in
M
metal-organic frameworks, Nature, 527(2015) 503-U193. [6] A. Bolin, M.M. Richter, Coreactant electrogenerated chemiluminescence of
[7]
Y.
Xu,
ED
ruthenium porphyrins, Inorg. Chim. Acta, 362(2009) 1974-1976. X.B.
Yin,
X.W.
He,
Y.K.
Zhang,
Electrochemistry
and
PT
electrochemiluminescence from a redox-active metal-organic framework, Biosens.
CC E
Bioelectron., 68(2015) 197-203. [8] S. Zhu, X. Lin, P. Ran, Q. Xia, C. Yang, J. Ma, Y. Fu, A novel luminescence-functionalized metal-organic framework nanoflowers electrochemi
A
-luminesence sensor via "on-off" system, Biosens. Bioelectron., 91(2017) 436-440. [9] F.Y. Zhao, W.J. Li, A. Guo, L. Chang, Y. Li, W.J. Ruan, Zn(II) porphyrin based nano-/microscale metal-organic frameworks: Morphology dependent sensitization and photocatalytic oxathiolane deprotection, RSC Adv., 6(2016) 26199-26202. [10] Y. Bai, Y. Dou, L.H. Xie, W. Rutledge, J.R. Li, H.C. Zhou, Zr-based 15
metal-organic frameworks: Design, synthesis, structure, and applications, Chem. Soc. Rev., 45(2016) 2327-2367. [11] G.Y. Zhang, Y.H. Zhuang, D. Shan, G.F. Su, S. Cornier, X.J. Zhang, Zirconium-based porphyrinic metal-organic framework (PCN-222): Enhanced photoelectrochemical response and its application for label-free phosphoprotein
IP T
detection, Anal. Chem., 88(2016) 11207-11212.
[12] D. Yang, S.O. Odoh, J. Borycz, T.C. Wang, O.K. Farha, J.T. Hupp, C.J. Cramer,
SC R
L. Gagliardi, B.C. Gates, Tuning zr-6 metal-organic framework (MOF) nodes as catalyst supports: Site densities and electron-donor properties influence molecular
U
iridium complexes as ethylene conversion catalysts, Acs Catalysis, 6(2016) 235-247.
N
[13] C.W. Kung, T.H. Chang, L.Y. Chou, J.T. Hupp, O.K. Farha, K.C. Ho,
A
Porphyrin-based metal-organic framework thin films for electrochemical nitrite
M
detection, Electrochem. Commun., 58(2015) 51-56. [14] G.Y. Zhang, C. Cai, S. Cosnier, H.B. Zeng, X.J. Zhang, D. Shan,
ED
Zirconium-metalloporphyrin frameworks as a three-in-one platform possessing oxygen nanocage, electron media, and bonding site for electrochemiluminescence
PT
protein kinase activity assay, Nanoscale, 8(2016) 11649-11657.
CC E
[15] W. Morris, B. Volosskiy, S. Demir, F. Gándara, P.L. McGrier, H. Furukawa, D. Cascio, J.F. Stoddart, O.M. Yaghi, Synthesis, structure, and metalation of two new highly porous zirconium metal–organic frameworks, Inorg. Chem., 51(2012)
A
6443-6445.
[16] N. Rathi, S. Rathi, I. Lee, J.W. Wang, M. Kang, D. Lim, M.A. Khan, Y. Lee, G.H. Kim, Reduction of persistent photoconductivity in a few-layer mos2 field-effect transistor by graphene oxide functionalization, RSC Adv., 6(2016) 23961-23967. [17] G. Liu, A.W. Robertson, M.J. Li, W.C.H. Kuo, M.T. Darby, M.H. Muhieddine, 16
Y.C. Lin, K. Suenaga, M. Stamatakis, J.H. Warner, Mos2 monolayer catalyst doped with isolated co atoms for the hydrodeoxygenation reaction, Nature Chem., 9(2017) 810-816. [18] S.X. Wu, Z.Y. Zeng, Q.Y. He, Z.J. Wang, S.J. Wang, Y.P. Du, Z.Y. Yin, X.P. Sun, W. Chen, H. Zhang, Electrochemically reduced single-layer MoS2 nanosheets:
IP T
Characterization, properties, and sensing applications, Small, 8(2012) 2264-2270.
[19] X. Xiang, J.B. Shi, F.H. Huang, M.M. Zheng, Q.C. Deng, J. Xu, MoS2
SC R
nanosheet-based fluorescent biosensor for protein detection via terminal protection of
small-molecule-linked DNA and exonuclease iii-aided DNA recycling amplification,
U
Biosens. Bioelectron., 74(2015) 227-232.
N
[20] W.S. Zhang, P.P. Zhang, Z.Q. Su, G. Wei, Synthesis and sensor applications of
A
MoS2-based nanocomposites, Nanoscale, 7(2015) 18364-18378.
M
[21] T. Wang, K. Du, W. Liu, J. Zhang, M. Li, Electrochemical sensors based on molybdenum disulfide nanomaterials, Electroanalysis, 27(2015) 2091-2097.
ED
[22] B.R. Garrett, S.M. Polen, M. Pimplikar, C.M. Hadad, Y. Wu, Anion-redox mechanism of MoO(S2)2(2,2’-bipyridine) for electrocatalytic hydrogen production, J.
PT
Am. Chem. Soc., 139(2017) 4342.
CC E
[23] W. Gu, Y.H. Yan, C.L. Zhang, C.P. Ding, Y.Z. Xian, One-step synthesis of water-soluble MoS2 quantum dots via a hydrothermal method as a fluorescent probe for hyaluronidase detection, Acs Appl. Mater. Interfaces, 8(2016) 11272-11279.
A
[24] B. Zhao, C. Shang, N. Qi, Z.Y. Chen, Z.Q. Chen, Stability of defects in monolayer MoS2 and their interaction with O2 molecule: A first-principles study, Appl. Surf. Sci., 412(2017) 385-393. [25] Y. Tong, Y. Liu, Y. Zhao, J. Thong, D.S.H. Chan, C. Zhu, Selectivity of MoS2 gas sensors based on a time constant spectrum method, Sens. Actuators, A:Phy., 255(2017) 17
28-33. [26] P. Joensen, R.F. Frindt, S.R. Morrison, Single-layer MoS2, Mater. Res. Bull., 21(1986) 457-461. [27] S. Xu, D. Li, P. Wu, One-pot, facile, and versatile synthesis of monolayer MoS2/
evolution reaction, Adv. Funct. Mater., 25(2015) 1127-1136.
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WS2 quantum dots as bioimaging probes and efficient electrocatalysts for hydrogen
[28] M. Jeong, S. Kim, S.-Y. Ju, Preparation and characterization of a covalent
SC R
edge-functionalized lipoic acid–MoS2 conjugate, RSC Adv., 6(2016) 36248-36255.
[29] H. Huang, C. Du, H. Shi, X. Feng, J. Li, Y. Tan, W. Song, Water-soluble
U
monolayer molybdenum disulfide quantum dots with upconversion fluorescence, Part.
N
Part. Syst. Char., 32(2015) 72-79.
A
[30] W.R. Cai, G.Y. Zhang, K.K. Lu, H.B. Zeng, S. Cosnier, X.J. Zhang, D. Shan,
M
Enhanced electrochemiluminescence of one-dimensional self-assembled porphyrin hexagonal nanoprisms, Acs Appl. Mater. Interfaces, 9(2017) 20904-20912.
ED
[31] A.B. Laursen, S. Kegnæs, S. Dahl, I. Chorkendorff, Molybdenum sulfides—efficient and viable materials for electro - and photoelectrocatalytic
PT
hydrogen evolution, Energ. Environ. Sci., 5(2012) 5577.
CC E
[32] M.V. Bollinger, J.V. Lauritsen, K.W. Jacobsen, J.K. Norskov, S. Helveg, F. Besenbacher, One-dimensional metallic edge states in MoS2, Phys. Rev. Lett., 87(2001) 196803.
A
[33] Y. Li, H. Wang, L. Xie, Y. Liang, G. Hong, H. Dai, MoS2 nanoparticles grown on graphene: An advanced catalyst for the hydrogen evolution reaction, J. Am. Chem. Soc., 133(2011) 7296-7299. [34] X.B. Li, Y.J. Gao, H.L. Wu, Y. Wang, Q. Guo, M.Y. Huang, B. Chen, C.H. Tung, L.Z. Wu, Assembling metallic 1T- MoS2 nanosheets with inorganic-ligand stabilized 18
quantum dots for exceptional solar hydrogen evolution, Chem. Commun., 53(2017) 5606-5609 [35] R.M. Clark, B.J. Carey, T. Daeneke, P. Atkin, M. Bhaskaran, K. Latham, I.S. Cole, K. Kalantar-Zadeh, Two-step synthesis of luminescent MoS2-ZnS hybrid quantum dots, Nanoscale, 7(2015) 16763-16772.
IP T
[36] C. Ma, H. Zhu, J. Zhou, Z. Cui, T. Liu, Y. Wang, Y. Wang, Z. Zou, Confinement
effect of monolayer MoS2 quantum dots on conjugated polyimide and promotion of
SC R
solar-driven photocatalytic hydrogen generation, Dalton Trans, 46(2017) 3877-3886.
[37] P. Thomas, A. Gangopadhyay, S.G. Jr, C. Andrews, H. Nakazato, S. Oikawa, J.M.
U
Jessup, The effect of transfection of the cea gene on the metastatic behavior of the
N
human colorectal cancer cell line MIP-101, Cancer Lett., 92(1995) 59-63.
A
[38] N. Van Anh, H. Van Trung, B.Q. Tien, N.H. Binh, C.H. Ha, N. Le Huy, N.T. Loc,
M
V.T. Thu, T.D. Lam, Development of a pmma electrochemical microfluidic device for carcinoembryonic antigen detection, J. Electron. Mater., 45(2016) 2455-2462.
electrochemical
ED
[39] L. Tian, L. Liu, Y. Li, Q. Wei, W. Cao, Ultrasensitive sandwich-type immunosensor
based
on
trimetallic
nanocomposite
signal
CC E
30849.
PT
amplification strategy for the ultrasensitive detection of CEA, Sci. Rep., 6(2016)
[40] Q. Liu, Y. Yang, X.P. Liu, Y.P. Wei, C.J. Mao, J.S. Chen, H.L. Niu, J.M. Song, S.Y. Zhang, B.K. Jin, A facile in situ synthesis of MIL-101-CdSe nanocomposites for
A
ultrasensitive electrochemiluminescence detection of carcinoembryonic antigen, Sens. Actuators, B: Chem., 242(2017) 1073-1078.
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Author Biographies Wenli Xin is currently studying for degree of MS in School of Environmental and Biological Engineering, Nanjing University
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of Science & Technology, PR China.
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Lianfu Jiang is currently studying for degree of Ph.D in MIIT Key Laboratory of Advanced Display Materials and Devices,
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Nanjing University of Science and Technology, PR china.
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Liping Zong is currently studying for degree of MS in School of
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Environmental and Biological Engineering, Nanjing University
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of Science & Technology, PR China.
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Haibo Zeng is presently employed as a professor in MIIT Key Laboratory of Advanced Display Materials and Devices, Nanjing University of Science and Technology, PR china. He received her MS in Applied mathematics from Hubei University, China in 2003, and her PhD in electrochemistry from Institute of Biophysics, Chinese Academy of Sciences in
2006. He current fields of interest include research on new display and special sensing 20
materials. GuoFang Shu is presently employed as a dorctor in Clinical laboratory
of
Zhongda
Hospital,
Affiliated
to
Southeast University. He received his MS in Southeast University, China in 2013, and he was associate chief
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technician in Clinical laboratory of Zhongda Hospital form 2015 to now.
Department
of
Biotechnology
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Robert S. Marks is presently employed as a professor in Engineering,
Ben-Gurion
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University of the Negev, Beer-Sheva, Israel. He received his
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MS Physiology and Cell Biology from University of California,
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Santa Barbara, USA in 1987, and PhD Chemical Immunology,
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The Weizmann Institute of Science, Rehovot, Israel in 1992. The main focus remains diagnostics (mainly biosensors), with the latest novel technology,
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electrolateral flow immunosensor.
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Dan Shan is presently employed as a professor in School of Environmental
and
Biological
Engineering,
Nanjing
University of Science & Technology, PR China. She received her MS in physical chemistry from Yangzhou University, China in 2001, and her PhD in electrochemistry from Joseph
Fourier University of Grenoble (France) in 2004. She worked at School of Chemistry & Chemical Engineering, Yangzhou University, PR China from 2004 to 2011. Her current fields of interest include biosensor, interfacial electrochemistry and 21
electroconductive polymer. Xue-Ji Zhang is a professor and Dean in school of chemistry and biological engineering, University of Science and Technology Beijing, PR China. He received his PhD in electrochemistry from Wu Han University, PR China (1989). current
fields
of
interest
include
bio-analysis,
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His
electrochemical sensors and biosensors, microelectrodes,
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ultramicroelectrodes and nanoelectrodes, nanosensors, free radical sensors.
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Figure captions
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Figure 1 (A) ECL-potential curves of GCE/ MQDs (a), GCE/MOF-545-Zn (b) and GCE/MOF-545-Zn@MQDs (c) O2-saturated in pH 7.4 HEPES solution during a
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continuous potential scan between −1.8 and 0 V, scan rate: 100 mV s−1. (B) ECL–time response of GCE/MOF-545-Zn@MQDs recorded in O2-saturated pH 7.4 HEPES
solution during a continuous potential scan between −1.8 and 0 V, scan rate: 100 mV
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s−1. (C) ECL-potential curve of GCE/MOF-545@MQDs in N2-saturated (a),
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Air-saturated (b) and O2-saturated (c) in pH 7.4 HEPES solution. (D)
and
Zn-TCPP
(d),
in
ethanol.
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(c)
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Photoluminescence spectrum of MQDs (a), MOF-545-Zn (b), MOF-545-Zn@MQDs Inset
D:
ECL
spectrum
of
GCE/MOF-545-Zn@MQDs in the O2-saturated pH 7.4 HEPES solution biased at
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−1.68 V.
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Figure 2 CVs of (A) GCE/MOF-545-Zn, (B) GCE/MQDs, (C) GCE/MOF-545-Zn@ MQDs in the N2-saturated (a) and O2-saturated (b) pH 7.4 HEPES solution during a
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continuous potential scan between −1.8 and 0 V, scan rate: 100 mV s−1. (D) EIS of bare GCE (a), GCE/MOF-545-Zn (b), GCE/ MQDs (c), GCE/MOF-545-Zn@MQDs 4−/3−
.
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(d) in the in 0.1 M KCl solution containing 5 mM Fe(CN)6
Figure 3 (A) SEM image of MOF-545-Zn. Inset A: Enlarged SEM image of MOF-545-Zn. (B) TEM image of MQDs. (C) AFM image of MQDs deposited on a glass substrate (a region of small coverage is shown to determine the thickness of the film), Insect B: Height profile of the film along the line depicted in (C). (D) TEM 23
image of Zn-545-Zn@MQDs. Figure 4 XPS of MQDs Mo3d (A), S2p (C), MOF-545-Zn C1s (E) and MOF-545-Zn@MQDs Mo3d (B), S2p (D), C1s (F). Figure 5 (A) ECL–potential curves of the modified electrode at different
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concentrations of CEA (a–h: 0, 0.0001, 0.002, 0.01, 0.04, 0.1, 0.4, 1.0 μg/mL). Inset A: The calibration plots of ECL peak intensity versus the logarithm of CEA
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concentration. Error bar =RSD (n=5). (B) Addition 5 μL real sample that CEA concentration was 1.13 ng/mL (1), 4.94 ng/mL (2), 8.36 ng/mL (3), 21.88 ng/mL (4), 50.24 ng/mL (5)1 in 95 μL test sample that concentration was 40 ng/mL CEA. (Red:
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theoretical value; blue: real value). Error bar =RSD (n=5).
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Scheme 1 Schematic illustration for the ECL mechanism of singlet oxygen and the
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construction of CEA immunosensor based on GCE/MOF-545-Zn@ MQDs
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Figure 4
28
Figure 5
29
A ED
PT
CC E
IP T
SC R
U
N
A
M
A
.
30
ED
PT
CC E
IP T
SC R
U
N
A
M
A ED
PT
CC E
IP T
SC R
U
N
A
M
Scheme 1
31