Trimetallic Hybrid Nanoflower-Decorated MoS2 Nanosheet Sensor for

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Trimetallic Hybrid Nanoflower-Decorated MoS2 Nanosheet Sensor for Direct In Situ Monitoring of H2O2 Secreted from Live Cancer Cells Baoting Dou, Jianmei Yang, Ruo Yuan, and Yun Xiang Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.analchem.8b00894 • Publication Date (Web): 13 Apr 2018 Downloaded from http://pubs.acs.org on April 13, 2018

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Analytical Chemistry

Trimetallic Hybrid Nanoflower-Decorated MoS2 Nanosheet Sensor for Direct In Situ Monitoring of H2O2 Secreted from Live Cancer Cells Baoting Dou, Jianmei Yang, Ruo Yuan and Yun Xiang* Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China E-mail: [email protected] (Y. Xiang). * Corresponding author. Tel.: +86-23-68252277 (Y. Xiang). ABSTRACT In situ monitoring of hydrogen peroxide (H2O2) secreted from live cells plays critical roles in elucidating many cellular signaling pathways, and it is of significant challenge to selectively detect these low levels of endogenous H2O2. To address this challenge, we report the establishment of a trimetallic hybrid nanoflower-decorated MoS2 nanosheet-modified sensor for in situ monitoring of H2O2 secreted from live MCF-7 cancer cells. The Au-Pd-Pt nanoflower-dispersed MoS2 nanosheets are synthesized by a simple wet-chemistry method, and the resulting nanosheet composites exhibit significantly enhanced catalytic activity toward electrochemical reduction of H2O2, due to the synergistic effect of the highly dispersed trimetallic hybrid nanoflowers and the MoS2 nanosheets, thereby resulting in ultra-sensitive detection of H2O2 with a sub-nanomolar level detection limit in vitro. Besides, the immobilization of the laminin glycoproteins on the surface of the nanocomposites increases its biocompatibility for cell adhesion and growth, which enables in situ electrochemical monitoring of H2O2 directly secreted from live cells for potential application of such sensor in cellular biology, clinical diagnosis and pathophysiology.

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INTRODUCTION Reactive oxygen species (ROS), generally including the peroxides, super-oxide, hydroxyl radical and singlet oxygen, is a kind of significant products in the metabolism of oxygen.1 The endogenous ROS plays a crucial role in cell signaling by modulating many different types of cell functions and physiological processes.2,3 For instance, hydrogen peroxide (H2O2), as the most stable ROS, is related to immune responses, signal transduction of cells, and pathogen invasion.4,5 With the diffusion distance of about 1.5 mm, H2O2 can penetrate cell membranes and almost cellular organelles. In this regard, overexpression of H2O2 can induce irreversible damages to several biological processes, such as peroxidation of nucleic acids, unsaturated fatty acids and cell membrane lipids, which may eventually lead to neurodegenerative disorders, diabetes and cardiovascular diseases.6,7 Therefore, in situ monitoring of H2O2 released from live cells is of great significance for clinical diagnosis and cell functions. Conventional spectrophotometric approaches including chemiluminescence,8 and fluorescence,9,10 have been demonstrated to be useful for the determination of H2O2 in vitro. Yet, the application of these methods for in situ monitoring of H2O2 secreted from live cells encounters significant challenges due to the low amount of H2O2 released from cells and the lack of effective signal probes responsive to cellular H2O2. Electrochemical techniques, however, with the unique advantages of high sensitivity and selectivity, rapid response, cost and miniaturization can achieve simple and sensitive detection of H2O2.11,12 Moreover, the electrochemical method can also offer an convenient interface to bridge cells and the sensing electrode,13 making these electrochemical sensors particularly suitable for the detection of H2O2 secreted from live cells. This has triggered recent development of various modified sensing electrodes based on inorganic nanomaterials14,15 and organic polymers16,17 for in situ detection of H2O2. For example, a multifunctional biointerface involving the layered graphene-artificial peroxidase-protein nanostructures with good cell adhesion and growth has been constructed for in situ selective and quantitative electrochemical detection of H2O2.14 Besides, a horseradish peroxidase (HRP) embedded and self-assembled peptide hydrogel has also been reported for detecting H2O2 released from live ACS Paragon Plus Environment 2

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cells.16 Despite these advancements, current electrochemical sensors for in situ detection of H2O2 require complicated fabrication processes and the biocompatibility for cell adhesion and growth as well as the sensitivity and selectivity for complex physiological environment still needs to be further improved. Therefore the development of new interfaces with high analytical performances and good biocompatibility for cells will significantly facilitate in situ detection of H2O2. In this regard, we report herein convenient synthesis of trimetallic hybrid nanoflower-decorated MoS2 nanosheets for in situ monitoring of H2O2 secreted from live cancer cells. Nanomaterials exhibit unique electrical, catalytic and mechanical properties over conventional bulk materials, due to their high surface-to-volume ratio and small size. For example, MoS2 nanosheets have favorable electrocatalytic activity toward the reduction of H2O2, ascribing to the enhancement of the planar electric transportation properties assisted by the electron-electron correlations.18,19 With a lower charge transfer resistance and more available reaction sites, MoS2 nanosheet-templated noble metal composites have also shown immense potential for high-performance electrochemical biosensors.20-22 Besides, bimetallic or even trimetallic nanoparticles consisted of different metal elements have shown enhanced catalytic performances over the corresponding single-phase counterparts due to their unique properties,23,24 and highly branched or dispersed nanostructures are also useful for improving the catalytic activity of the nanomaterials.25,26 On the other hand, the extracellular matrix of laminin is a large cross-shaped glycoprotein, which can be found in the basement membranes of cells and is associated with cell proliferation, adhesion, and migration.27,28 Research evidences have shown that laminin can be immobilized on the surface of nanomaterials without the loss of any functions and the surface can serve as a biocompatible substrate for boosting cell attachment and differentiation.29 Based on these facts, our approach for in situ monitoring of H2O2 using the trimetallic hybrid nanoflower-decorated MoS2 nanosheets shows two major advantages. First, the modified MoS2 nanosheets with high catalytic performance toward electrochemical reduction of H2O2 can be synthesized in a homogeneous one-step format. Second, the superior biocompatibility of the designed interface with the assistance of laminin



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can improve cell adhesion and growth. The integration of the advantages in the sensor design thus provides promising potentials for sensitive monitoring of H2O2 secreted from live cancer cells.

EXPERIMENTAL SECTION Materials and reagents: Pluronic F127 (Mw=12600), potassium tetrachloroplatinate (K2PtCl4, 99%), sodium chloropalladite (Na2PdCl4, 98%), hexadecylpyridinium chloride monohydrate (HDPC, 98%), gold chloride (HAuCl4, 99%), dimethyl sulfoxide (DMSO), L-ascorbic acid (AA, 99%), H2O2 (30%), uric acid (UA), sodium nitrite (NaNO2), laminin, phorbol 12-myristate-13-acetate (PMA) and catalase were all supplied by Sigma-Aldrich Shanghai Trading Co., Ltd. (Shanghai, China). MoS2 nanosheets were purchased from JCNANO Technology Co., Ltd. (Nanjing, China). The cell culture reagents were obtained from Dingguo Biological Technology Co., Ltd. (Chongqing, China). The MCF-7 cell line was provided by the cell bank of the type culture collection of the Chinese Academy of Sciences (Shanghai, China). Disposable screen-printed carbon electrode (SPCE) with a carbon 3-mm diameter working electrode, a silver pseudo reference electrode and a carbon-based control electrode, was bought from Zensor R&D Co., Ltd (Taichung, Taiwan). Ultrapure water was used throughout the experiments. Synthesis of the trimetallic nanoflower-decorated MoS2 nanosheets (Au-Pd-Pt/MoS2): The trimetallic nanoflower-decorated MoS2 nanosheets were synthesized by using a wet-chemical method,30,31 employing the Pluronic F127 and HDPC surfactants as the micellar templates. The aqueous solution (2.5 mL) consisting of Pluronic F127 (4.3 mg) and HDPC (0.35 mg) were first prepared in a beaker. Subsequently, HAuCl4 (30 L, 10 mM), Na2PdCl4 (120 L, 10 mM) and K2PtCl4 (120 L, 10 mM) were added in succession into the beaker under mild stirring, followed by sonication with MoS2 (500 L, 2.5 mg mL-1) suspension for 30 min. AA (450 L, 30.4 mM) was then added slowly to the aqueous solution, and the mixture was stirred vigorously for 1 hour at room temperature. The resulting mixture was finally centrifuged at 8000 rpm for 10 min and washed with ultrapure water three times to obtain the Au-Pd-Pt/MoS2 nanosheets. ACS Paragon Plus Environment 4

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Construction of the sensing interface: The SPCE as the substrate was first pretreated in Tris-HCl buffer (20 mM, pH 7.4) by scanning the potential (scan rate of 0.5 V s−1) in the range between -0.6 and +0.6 V. The obtained Au-Pd-Pt/MoS2 (10 L, 2 mg mL-1) was cast onto the pretreated SPCE and dried in the air, denoted as Au-Pd-Pt/MoS2/SPCE. The modified SPCE was then sterilized through irradiation under UV light for 15 min prior to use. Laminin (10 L, 20 g mL-1) was further incubated with the Au-Pd-Pt/MoS2/SPCE for 30 min at 25 °C, and the laminin/Au-Pd-Pt/MoS2/SPCE was washed three times with sterile phosphate buffer (6.7 mM, pH 7.2) before plating cells. Cell culture: According to previously reported method,32,33 MCF-7 cells were cultured in Dulbecco’s modified Eagle medium (DMEM) solution containing 1% penicillin, 1% streptomycin, and 10% fetal bovine serum in a humidified atmosphere of 5% CO2 for 24 h at 37 °C in the culture dishes. To culture cells on the sensing interfaces, the cells were then removed from the petri dish by trypsinization and washed three times with sterile buffer, followed by being suspended in fresh DMEM. Subsequently, the suspension of cells (1×105 cells mL-1, 10 L) was cast to the sensing interfaces and allowed to stay at 37 °C in a humidified incubator (95% air with 5% CO2) for different time frames. In situ detection of H2O2 released from cells: After the culture of the MCF-7 cells on the interface for 2 hours, MCF-7/laminin/Au-Pd-Pt/MoS2/SPCE was washed carefully by using sterile phosphate buffer for three times to remove the culture medium. After that, N2 purged phosphate buffer (50 L, 10 mM, pH 7.4) as electrolyte was dropped on the prepared interface, current responses upon injecting PMA (1 L, 50 μg mL−1) were recorded for quantitative detection of H2O2 released from cells. Apparatus: Scanning electron microscopy (SEM) images and transmission electron microscopy (TEM) photographs were respectively obtained on a Hitachi S-4800 scanning electron microscope (Tokyo, Japan) at an acceleration voltage of 30 kV and a JEM 1200EX microscope operated at 120 kV. The MCF-7 cells cultured on different interfaces were first fixed with paraformaldehyde/sucrose (4% w/v) at room temperature for 15 min and dehydrated using various concentrations of ethanol (15%, 30%, 50%, 70%, 80%, 90%, 100%). The samples were then dried at room temperature and coated with Au by a ion ACS Paragon Plus Environment 5


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sputter system (Hitachi E-1010) for 20 s, followed by recording with SEM. Cyclic voltammograms (CV) and typical current-time curves were recorded on a CHI 852C electrochemical workstation (CH Instruments, Shanghai, China). RESULTS AND DISCUSSION

Scheme 1. Schematic illustration for (A) one step synthesis of the trimetallic Au-Pd-Pt nanoflower-decorated MoS2 nanosheets and (B) in situ electrochemical monitoring of H2O2 secreted from live MCF-7 cancer cells. Synthesis and characterization of the Au-Pd-Pt/MoS2 nanosheets. The Au-Pd-Pt/MoS2 nanosheets were synthesized by using a one-step wet-chemical synthesis method as depicted in Scheme 1A. The micellar template based on Pluronic F127 and HDPC attributes to the structure of the highly-branched trimetallic hybrid nanoflowers, and AA is used as the reducing agent. During the process, part of the Au precursor is firstly reduced as initial seeds on the MoS2 substrate due to more positive standard reduction potential of Au ions, and then Au, Pd and Pt sources rapidly nucleate, resulting in the blooming of the homogeneous flower-like nanostructures on the MoS2 nanosheets.


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Figure 1. SEM images of (A) MoS2 nanosheets and (B) Au-Pd-Pt/MoS2; (C) and (D) TEM images of Au-Pd-Pt/MoS2; (E) SEM-EDS profile of the Au-Pd-Pt/MoS2; (F) size distribution of the Au-Pd-Pt nanoflowers. The morphologies of the as prepared Au-Pd-Pt/MoS2 nanosheets were characterized by SEM and TEM. The typical SEM image of Figure 1A shows the sheet-like structure of MoS2 nanosheets with diameter from 200 nm to 500 nm deposited on Si substrate. Well-dispersed trimetallic nanostructures can be clearly observed on the MoS2 nanosheets in Figure 1B, and more trimetallic nanostructures are observed at the edges of the MoS2 nanosheets due to the high density of energetic defects at the edges.34,35 Such observations are further confirmed by TEM characterizations. According to Figure 1C, the Au-Pd-Pt trimetallic nanoflowers are uniformly decorated on the MoS2 nanosheets, which is consistent with the SEM observation in Figure 1B. Besides, the TEM image with enhanced magnification on the sample (Figure 1D) reveals the highly branched nanoflower structure of the Au-Pd-Pt trimetallic nanohybrids. Moreover, energy-dispersive X-ray spectroscopy (EDS) was then employed to investigate the composition of the Au-Pd-Pt/MoS2 nanosheets. As shown in Figure 1E, the appearance of the corresponding elemental peaks indicates that the hybrid nanomaterials are composed of Au, Pd, Pt, Mo and S as expected. The size of the Au-Pd-Pt trimetallic nanoflowers was also ACS Paragon Plus Environment 7


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analyzed by using the Nano Measurer 1.2. From Figure 1F, it is evident that the size of the nanoflowers on the MoS2 substrate ranges narrowly from 14 to 26 nm and the mean diameter is about 20 nm. These characterizations thus suggest the successful preparation of the Au-Pd-Pt/MoS2 nanosheets.

Figure 2. SEM images of MCF-7 cells cultured on different interfaces: (A) Au-Pd-Pt/MoS2/SPCE and (B) laminin/Au-Pd-Pt/MoS2/SPCE. MCF-7 cells were cultured in DMEM solution with 5% CO2 at 37 °C for 24 h. Culture of MCF-7 cells on the interfaces. In order to apply the synthesized Au-Pd-Pt/MoS2 nanosheets for in situ monitoring of H2O2 secreted by cells, these nanosheets should have significant biocompatibility for cell adhesion and growth. To this purpose, the laminin glycoproteins were immobilized on the Au-Pd-Pt/MoS2 nanosheets through physical adsorption to build the biointerface, and the adhesion and growth of the target MCF-7 cancer cells on the interfaces were further assessed by SEM. As shown in Figure 2A, only a few MCF-7 cells with spherical morphologies can be observed on the Au-Pd-Pt/MoS2 nanosheets after culturing the cells for 24 h, which indicates the poor growth of cells due to the limited cell adhesion capability and negative charge of the interface. On the contrary, it can be clearly seen in Figure 2B that the introduction of laminin on the surface of the Au-Pd-Pt/MoS2 nanosheets leads to significant increase in the number of MCF-7 cells. Besides, some pseudopodia are also observed in the inset of Figure 2B, suggesting effective capture of cells by laminin, which is in accordance with previous reports that cells typically adhere better to positively charged surface.29,36


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Figure 3. (A) Typical CV responses of (a) bare SPCE in the absence of H2O2; (b) SPCE, (c) MoS2/SPCE, (d) Au-Pd-Pt/MoS2/SPCE and (e) laminin/Au-Pd-Pt/MoS2/SPCE in the presence of 50 nM H2O2 in N2 saturated phosphate buffer at scan the rate of 50 mV s−1. (B) Selectivity profile of laminin/Au-Pd-Pt/MoS2/SPCE at different applied potentials from -0.3 V to +0.3 V. Analytical performance of laminin/Au-Pd-Pt/MoS2 nanosheet-modified SPCE for in vitro detection of H2O2. The electrocatalytic capabilities of different interfaces toward H2O2 were assessed by performing CV in N2 saturated phosphate buffer. As can be seen in Figure 3A, there is no reduction or oxidation peaks (curve a) that can be observed on the bare SPCE in the absence of H2O2 from -0.6 to 0.6 V, due to the fact that there is no any electroactive species present in buffer, and the addition of 50 nM H2O2 causes neglect changes in the current response (curve b), suggesting that the sensitivity of the unmodified SPCE is unable to detect H2O2 at such concentration. However, the presence of 50 nM H2O2 on the MoS2/SPCE can lead to obvious reduction current response at about -0.3 V (curve c), revealing the catalytic activity of MoS2 nanosheets for the reduction of H2O2, which is confirmed by previous reports.19,37 Moreover, the Au-Pd-Pt/MoS2/SPCE shows significantly enhanced electrocatalytic reduction of H2O2 with ~200% increase in current response (curve d vs. c). Such an increase is basically due to the synergistic enhancement on the catalytic activity by the trimetal hybrid nanoflowers and MoS2 nanosheets. Although the adsorption of laminin on the Au-Pd-Pt/MoS2/SPCE results in a small decrease in current response for electro-reduction of H2O2 (curve e), owing to the increased electron transfer resistance by the surface-adsorbed laminin glycoproteins, it still shows sensitive current response for H2O2. The current-time response was further used to evaluate the specificity of the laminin/Au-Pd-Pt/MoS2/SPCE, and its amperometric response to various interferences under different applied potentials was shown in Figure 3B. As can be seen form this figure, electro-reduction of H2O2 on laminin/Au-Pd-Pt/MoS2/SPCE shows increasing current response from +0.3 to 0 V and remains almost unchanged when the potential is lowered to -0.3 V. While, the cathodic interference (NaNO2) and anodic interferences (AA, UA) exhibit current responses at the low (from -0.1 to -0.3 V) and high (from +0.1 to +0.3 V) potentials, respectively, indicating that these potentials are not suitable for ACS Paragon Plus Environment 9


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selective detection of H2O2. It is also obvious that the current response contributions from the interferences are minimized at 0.0 V. Based on these comparisons, the potential for electro-reduction of H2O2 on laminin/Au-Pd-Pt/MoS2/SPCE was then set at 0.0 V.

Figure 4. (A) Current-time responses of laminin/Au-Pd-Pt/MoS2/SPCE to 1, 5, 8, 10, 20, 50, 80 and 100 nM of H2O2 (from a to h). (B) Calibration curve of the amperometric responses to the concentrations of H2O2 from 1 nM to 100 nM. After optimizing the potential, the detection sensitivity of the laminin/Au-Pd-Pt/MoS2/SPCE sensor for H2O2 was further investigated by using electrochemical current-time response curves. In this regard, the laminin/Au-Pd-Pt/MoS2/SPCE was challenged with different concentrations of H2O2 in N2 saturated phosphate buffer at 0.0 V. From Figure 4A, it is observed that the amperometric current response increases with elevated concentration of H2O2 from 1 nM to 100 nM, and the current response is determined to be proportional to the concentration of H2O2 in the investigated range as shown in Figure 4B. The linear regression equation is found to be i (A) = 0.31255 + 0.05914 c (nM) with a good linearity (R2 = 0.9967), and the detection limit for H2O2 is estimated to be 0.3 nM. In addition, six repetitive experiments for the measurement of H2O2 at 10 nM led to a relative standard deviation of 3.9%, further suggesting good reproducibility of the biosensing interface. Compared with previously reported H2O2 sensors based on other nanomaterials or enzymes, our detection method shows an improved sensitivity as can be seen in Table 1.


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Table 1 Comparison of different electrochemical sensors for the detection of H2O2 Sensor Linear range Detection limit Reference Dealloyed AuNi Dendrite Anchored on a Functionalized Conducting Polymer

5 nM to 40 nM

5 nM

9

Horseradish peroxidase

0.1 M to 60 M

18 nM

16

Cytochrome c

0.3 M to 800 M

50 nM

17

Ultrasmall MoS2 Nanoparticles

5.0 nM to 100 nM

2.5 nM

19

Platinum Nanoparticle on Graphene Hybrid Nanosheet

1 M to 500 M

80 nM

38

Core/Shell Au/MnO Nanoparticles

20 nM to 100 nM

8 nM

39

Copper(I) Phosphide Nanowires

0.005 μM to 0.10 μM

2 nM

40

Graphene/Intermetallic PtPb Nanoplates Composites

0.002 μM to 2516 μM

2 nM

41

Quasi-Core/Shell Structured TiO2@Cu2O

0.001 mM to 0.015 mM

0.15 μM

42

PtW/MoS2 hybrid nanocomposite

1 μM to 200 μM

5 nM

43

Au-Pd-Pt/MoS2

1 nM to 100 nM

0.3 nM

This work

Figure 5. (A) Current-time response curves of laminin/Au-Pd-Pt/MoS2/SPCE to (a) the addition of PMA without the cultured MCF-7 cells, the addition of (b) DMSO and (c) PMA and (d) catalase with ACS Paragon Plus Environment 11


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the cultured MCF-7 cells in N2 saturated phosphate buffer at 0.0 V. (B) The corresponding current responses of laminin/Au-Pd-Pt/MoS2/SPCE to the stimulations of (a) PMA without the cultured MCF-7 cells, (b) DMSO and (c) PMA with the cultured MCF-7 cells. In situ detection of H2O2 secreted from live MCF-7 cells. The application of the laminin/Au-Pd-Pt/MoS2/SPCE for in situ monitoring of H2O2 secreted from the cultured MCF-7 cells on the sensor was further evaluated. PMA, which can activate protein kinase c and cause the release of H2O2 from cells after a cascade of signaling events,44,45 was used as the stimulant to trigger the production of H2O2. Two control experiments were also performed by spiking PMA (1 μL, 50 μg mL−1) and DMSO (1 μL, 1% of volume fraction) to the sensor without and with the cultured MCF-7 cells, respectively. As shown Figure 5A, the control experiments exhibit no noticeable current responses (curves a and b), indicating that PMA itself has no effect on the current response and DMSO is unable to stimulate the production of H2O2 from the MCF-7 cells. However, when the same amount of PMA (1 μL, 50 μg mL−1) was added to laminin/Au-Pd-Pt/MoS2/SPCE cultured with MCF-7 cells, significant reduction current response (curve c) can be observed at the applied potential, suggesting that the secreted H2O2 can be sensitively detected by the sensor. Besides, the reduction current response caused by the PMA injection with the cultured MCF-7 cells can be further suppressed (curve d) by subsequent injection of catalase (1 μL, 5000 U mL−1), due to its capacity of selective scavenging of H2O2.46 The results shown here demonstrate that the developed laminin/Au-Pd-Pt/MoS2/SPCE sensor can be used for real time monitoring of H2O2 released from live cells. The corresponding current responses shown in Figure 5B were employed to calculate the average number (N0) of H2O2 released per cell based on the following formulation:14,16 N0={[∆R÷(k×A)×V]×NA}÷{ε×A}, where ∆R is the corresponding current response, k stands for sensitivity of the sensor, A corresponds to the electrode surface area, V is volume of the electrolyte, NA denotes the Avogadro constant (6.02×1023 mole-1), and ε is cell density. With a apparent current response of 216 nA, a sensitivity of 8.365 nA nM-1 mm-2, and a calculated electrode surface area of 7.07 mm2 and a cell density of 141 mm-2, as well as the volume of the electrolyte of 50 L, N0 is calculated to be around 1011 over 20 s, which is in agreement with the previous reports.14,16 ACS Paragon Plus Environment 12

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CONCLUSIONS In summary, simple preparation of trimetallic hybrid nanoflower-decorated MoS2 nanosheets and the application of such nanomaterials for enhanced catalytic electrochemical reduction of H2O2 have been demonstrated. The synergistic effect of the highly dispersed nanoflower nanostructures and the MoS2 nanosheets contributes to the high electrocatalytic activity of the composite nanomaterials, leading to a sub-nanomolar detection limit for H2O2. The introduction of the laminin glycoproteins on the surface of the Au-Pd-Pt/MoS2 sheets further increases its biocompatibility for the adhesion and growth of the MCF-7 cells, thereby enabling sensitive monitoring of H2O2 secreted from live cancer cells. With the results shown herein, the designed biointerface thus shows great promise for cellular functions, drug discovery and pathological investigations with the capability for in situ monitoring of cell secreted H2O2. AUTHOR INFORMATION Corresponding Author *Tel./Fax: +86-23-68252277; E-mail: [email protected]. Notes The authors declare no competing financial interest. ACKNOWLEDGMENT This work was supported by National Natural Science Foundation of China (No. 21675128) and Fundamental Research Funds for the Central Universities (XDJK2017A001). REFERENCES (1) Reddy, J. K.; Lalwani, N. D.; Reddy, M. K.; Qureshi, S. A. Cancer Res. 1982, 42, 259–266. (2) Winterbourn, C. C. Nat. Chem. Biol. 2008, 4, 278–286. (3) Amatore, C.; Arbault, S.; Bruce, D.; de Oliveira, P.; Erard, M.; Vuillaume, M. Chem. Eur. J. 2001, 7, 4171–4179. (4) Mroz, P.; Bhaumik, J.; Dogutan, D. K.; Aly, Z.; Kamal, Z.; Khalid, L.; Kee, H. L.; Bocian, D. F.; Holten, D.; Lindsey, J. S.; Hamblin, M. R. Cancer Lett. 2009, 282, 63–76. ACS Paragon Plus Environment 13


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Trimetallic Hybrid Nanoflower-Decorated MoS2 Nanosheet Sensor for

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