Multifunctional Fluorescent Nanoprobe for Sequential Detections of

Subscriber access provided by UNIV OF DURHAM

Article

Multifunctional fluorescent nanoprobe for sequential detections of Hg2+ ions and biothiols in live cells Lu He, Hui Tao, Seyoung Koo, Guo Chen, Amit Sharma, Yong Chen, In-Teak Lim, Qian-Yong Cao, and Jong Seung Kim ACS Appl. Bio Mater., Just Accepted Manuscript • DOI: 10.1021/acsabm.8b00300 • Publication Date (Web): 27 Aug 2018 Downloaded from http://pubs.acs.org on August 28, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Bio Materials

Multifunctional fluorescent nanoprobe for sequential detections of Hg2+ ions and biothiols in live cells Lu He a,‡, Hui Tao a,‡, Seyoung Koob,‡, Guo Chen c, Amit Sharmab, Yong Chen c, In-Taek Lim,d Qian-Yong Cao a,*, Jong Seung Kimb,* a

Department of Chemistry, Nanchang University, Nanchang 330031, China.

b

Department of Chemistry, Korea University, Seoul 02841, Korea.

c

Institute for Advanced Study, Nanchang University, Nanchang 330031, China.

d

Center for Teaching and Learning, Chunnam Techno University, Gokseong 57500, Korea

‡ These authors contributed equally to this work. *

Corresponding authors. E-mail: [email protected] (Q.-Y. Cao); [email protected] (J. S.

Kim)

ACS Paragon Plus Environment

ACS Applied Bio Materials 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Abstract Herein, we report an amphiphilic fluorescent probe consisting of a dansyl fluorophore as a reporter and a hydrophobic cetyl chain bridged by a triazole unit. The cetyl-based probe can selfassemble to form nanoaggregates in aqueous solution, as confirmed by Tyndall effect, dynamic light scattering (DLS), and transmission electron microscopy (TEM) measurements. This probe exhibited an “on-off” fluorescence quenching response toward Hg2+ ions in aqueous solution over other tested metal ions. In contrast, the analogous methyl-based probe barely exhibits Hg2+ ion sensing behavior under the same conditions. Moreover, the resulting complex of the cetylbased probe and Hg2+ (1-Hg2+, 1:1 stoichiometry) exhibited an efficient fluorescence “off-on” sensing for thiol-containing amino acids, including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH). This nanoprobe exhibited minimal cytotoxicity with excellent cell permeability and was efficiently tested for the imaging of intracellular Hg2+ and cysteine in live cells.

Keywords: Nanoaggregates; mercury sensing; thiols recognition; fluorescence imaging


Page 2 of 28

Page 3 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


1. Introduction Heavy metal poisoning, particularly caused by the accumulation of certain metal ions poses a serious threat to human health, environment and ecological systems even if present at ultra-low concentrations. Mercury is among the most prevalent toxic metals that have drawn considerable attention due to its high toxicity and bio-accumulation by the drinking water, and food intakes. Mercury exists in various forms, of which the Hg2+ ion is the most common oxidation form. By the action of bacteria, the Hg2+ ion can be converted into highly toxic methylmercury, which can be enriched by organisms via the food chain. Once inside the body, it may induce irreversible damages to DNA, central nervous system and brain resulting in various chronic diseases.1-4 Thus, ultrasensitive, biocompatible, rapid and efficient detection of Hg2+ in the environment and in biosystems is highly desired. In past, several traditional sensing technologies like, ultraviolet-visible absorption spectrometry,5 cold vapor atomic absorption spectrometry (CVAAS),6 and inductively coupled plasma mass spectrometry (ICPMS)7 have been developed for Hg2+ ions detection and quantification. However, due to complicated processes involved for sample preparations, expensive instrumentations and expertise personnel requirements in these techniques, numerous optical sensors has been developed with good response and operational ease. Especially, fluorescence methods for sensing Hg2+ ions have attracted considerable interest, because of their intrinsic sensitivity and selectivity.8-10 Many organic probes bearing different fluorophores as reporter, including rhodamine, pyrene, naphthalimide, boron dipyrromethene, and dansyl groups, has been developed for the selective sensing of Hg2+ ions.11-18 Among these, dansyl-based probes have attracted particular attention, because dansyl exhibits characteristic spectroscopic properties such as intense absorption bands in the near-UV, strong fluorescence in the visible region, and



sensitivity of the emission spectrum towards its microenvironment by the internal charge transfer (ICT) mechanism.19,20 Due to their high photostability, the dansyl dyes have been wildly applied in biological systems.21,22 Importantly, the lone-pair containing nitrogen atom of the sulfonamide group in the dansyl moiety serves as a good donor for Hg2+ ions, and its metal ion binding ability can be enhanced by the introduction of other donors.23 In this regard, various amino acids, calix[4]arenes, bile acid, and heterocyclic-ring-functionalized dansyls have been reported for Hg2+ ion recognition.24-30 However, many of these probes require complicated multi-step synthetic preparation. In addition, the reported examples are frequently employed in an organic solvent or semi-aqueous solution owing to the poor solubility and/or weak binding ability of the organic fluorophores in aqueous media. Therefore, it is significant to develop a simple, sensitive, bio-compatible and cost-effective sensor for sensing Hg2+ ions. The most abundant small-molecule biological thiols, Cys, Hcy, and GSH play key roles in various biological processes.31 Abnormal levels of these biothiols, particularly in cancer are known to be linked with progression of the disease and have been successfully utilized in the development of targeted therapeutics.32 Likewise, an abnormal level of Cys is a risk factor in liver damage, skin lesions, and slowed growth.33,34 Thus, a great deal of attention has been given to the detection of these thiol-containing amino acids. Until now, various reaction-based fluorescent probes utilizing different reaction mechanisms, including Michael addition, cleavage of sulfonate esters and sulfonamide, or cleavage of S–S bonds or Se–N bonds, has been developed for the detection of biothiols.35-48 Recently, sensing of biothiols using coordination metal complexes via the displacement approach has also been reported,46-55 based on the strong binding ability of the sulfur atom in biothiols toward some thiophilic metals, such as Hg2+ and Cu2+. Lately, self-assembled materials derived from small amphiphilic organic molecules have


Page 4 of 28

Page 5 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


gained considerable attention in chemosensors owing to their superior characteristics.56-60 By adjusting the structural features of organic building blocks, various topologies of nanoaggregates can be obtained in aqueous media. Compared to the small organic molecules, these nanoaggregates show superior characteristics, such as good biocompatibility, low cytotoxicity, and greater sensitivity to external stimuli. Some amphiphile-based nanoaggregates have been developed for the fluorescence sensing of anions and metal ions.61-65

Aqueous medium

= thiol-containing amino acids

Hg2+

Scheme 1. Schematic illustration of the recognition strategy of 1 toward Hg2+ and biothiols. In this context, we report here an amphiphilic dansyl based probe 1 for sequential sensing of Hg2+ ions followed by bothiols in aqueous solution (Scheme 1). In this probe, the dansyl moiety was chosen as both the reporter unit and primary metal ion binding site. The long hydrophobic cetyl chain leads to self-assembly in aqueous solution, and the “click”-reaction-derived triazole ring serves as an efficient covalent linker as well as an extra donor for metal ions.66,67 The cetyl chain is the most often used for formation of nanostructured aggregates in literature.61,68 It was found that probe 1 can easily self-assemble into nanostructured aggregates with strong green



Page 6 of 28

emission in pure aqueous solution, as confirmed by the DLS and TEM techniques. The nanoaggregates of 1 shows an “on-off” fluorescence quenching response, selective toward Hg2+ over other tested metal ions in the aqueous medium. Importantly, the assembled 1-Hg2+ complex can be used as an efficient fluorescence “off-on” sensor for thiol-containing amino acids, including Cys, Hcy, and GSH in aqueous solution. The sensing mechanism of the probe toward Hg2+ ions and thiol-containing amino acids is also discussed in detail. For comparison, the reference compound 2, bearing a short methyl chain is also prepared and tested.

2. Materials and Methods 2.1 General apparatus and reagents. All the reagents and solvents used for the synthesis and testing were analytically pure and used as received. 5-(Dimethylamino)-N-2-propyn-1-ylnaphthalene sulfonamide (2) and azidocythane (3) were synthesized using literature methods.69,70 UV-Vis absorption spectra were recorded using a Hitachi UV-4100 spectrophotometer. Emission spectra were recorded on a Hitachi F-4500 spectrophotometer. The 1H and

13

C NMR spectra

were obtained using Varian instruments (400 MHz). The respective chloride or perchlorate (Ag+) salts of the metal ions were used for titration and were prepared in aqueous solution. 2.2 Preparation of the nanoaggregates of 1 and its emission titrations. A high concentration (4.0 × 10–3 M) solution of 1 in DMSO was first prepared as stock. Then 10 µL of the stock solution was added dropwise into distilled water (2 mL) under rapid stirring to obtain the nanoaggregates; the concentration of 1 in the aqueous solution was 2.0 × 10–5 M (0.5% DMSO). Stock solutions of the metal ions (Hg2+, Cd2+, Zn2+, Cu2+, Pb2+, Cr3+, Ca2+, Ni2+, Fe2+, Co2+, Ag+, Mg2+, and Fe3+) (4.0 × 10–3 M) as their perchlorate salts and of the biologically relevant amino acid analytes (Cys, GSH, Hcy, Glu, Arg, Phe, Val, Tyr, Asn, Gly, Trp, Asp, His, Ala, Thr, Lys,


Page 7 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Met, and Leu) were prepared in the distilled water. Subsequently, using a micro-injector, different equivalents of the metal ions solution were added into the aqueous solution of 1, and the fluorescence emission of the resulting solutions were measured. For amino acid recognition, the 1-Hg2+ complex was generated in situ by the addition of equal amounts (2.0 × 10–5 M) of 1 and Hg2+ in distilled water, and subsequently different numbers of equivalents of the amino acids were added. The volumes of the metal ion or amino acid solutions added to the test solution of 1 were negligible. Hence, the total volume of the final system was considered as constant. 2.3 Cell culture and fluorescence imaging. Liver cancer HepG-2 cells were cultured in the Dulbecco’s modified Eagle’s medium (DMEM) and supplemented with fetal bovine serum (10%, FBS) (Invitrogen Corp., CA) and penicillin (100 units/mL)-streptomycin (100 µg/mL) liquid (Invitrogen Corp., CA) at 37 °C under a humidified atmosphere of 5% CO2 in air. The cells were incubated on an uncoated glass-bottomed dish (D110100, Matsunami, Japan) for 2 days. Subsequently, the cells were incubated with DMEM containing 10% phosphate-buffered saline (PBS) and 10 µM of probe 1 at 37 °C (30 min), washed with PBS (twice), and mounted on the microscope stage. The fluorescence images were recorded using a confocal laser-scanning microscope (Nikon A1) equipped with live cell workstation. Live HepG-2 cells were pretreated with 1 mM NEM for 30 min. Then the in situ cells were treated with 10 µM Hg2+ and Cys (50 µM) and further incubated for 30 minutes, and same set of cells was used for recording confocal laser-scanning microscopy measurements. 2.4 Cytotoxicity assay. Liver cancer HepG-2 cells were seeded into the 96-well plates for overnight in the Dulbecco’s modified Eagle’s medium (DMEM) with FBS (10%, v/v), and further treated with 0, 5, 10, 15, 20, 25, 30, 35, or 40 µM each of probe 1 at 37 °C for 24 h. Then, a freshly prepared 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT, 1



Page 8 of 28

mg/mL) (100 µL, PBS) solution was added and further incubated for 4 h. The supernatant was taken off cells were lysed with DMSO (100 µL) per well. The plates were shaken gently for next 5 min, and the absorbance spectra of purple formazan (520 nm) was recorded by using the Spectra MAX 340PC plate reader. 2.5 Synthesis of probe 1. Under a nitrogen atmosphere, 5-(dimethylamino)-N-2-propyn-1-ylnaphthalene sulfonamide 3 (120 mg, 0.41 mmol), azidocythane 4 (109.5 mg, 0.41 mmol), CuSO4·5H2O (20.5 mg, 0.08 mmol), and sodium ascorbate (24.4 mg, 0.12 mmol) were taken in a round bottom flask containing DMF (3 mL). The resulting mixture was stirred at room temperature (RT) for 4 h. Then, 30 mL ethyl acetate was added to dilute the mixture, and the resulting mixture was washed with water (3 × 30 mL). Organic phase was separated, dried over MgSO4 and filtered, and then the solvent was concentrated under vaccum. The crude mixture was purified by column chromatography (CH2Cl2/MeOH, 98:2, v/v) to yield 1 as a yellow powder (197.3 mg, yield 86%). 1H NMR (400 MHz, CDCl3): δ = 8.53 (1 H, d, J = 8.5), 8.25 (2 H, d, J = 7.6 Hz), 7.52 (2 H, dt, J = 11.0 Hz, 8.3 Hz), 7.21 (1 H, s), 7.17 (1 H, d, J = 7.5 Hz), 5.54 (1 H, t, J = 5.8 Hz), 4.21 (2 H, d, J = 6.0 Hz), 4.15 (2 H, t, J = 7.3 Hz), 2.88 (6 H, s), 1.79– 1.69 (3 H, m), 1.25 (28 H, s).

13

C NMR (101 MHz, CDCl3): δ = 150.9, 133.7, 129.5, 128.8,

128.5, 127.5, 122.1, 117.8, 114.3, 49.3, 44.4, 37.7, 30.9, 29.1, 28.8, 28.5, 28.3, 28.2, 27.9, 25.4, 21.7, 13.1. TOF-HRMS: Calcd. for [C31H49N5O2S]+ 555.3607; Found 556.3684 (M+ +1).

2.6 Synthesis of probe 2. This compound was prepared using the procedure similar to that of 1. 1

H NMR (400 MHz, CD3CN): δ = 8.54(1H, d, J = 8.4 Hz), 8.20 (2H, dd, J1 = 4.0 Hz, J2 = 10.4

Hz), 7.58 (2H, dd, J1 = 8.0 Hz, J2 = 10.4 Hz), 7.27 (1H, d, J = 7.6 Hz), 7.19 (1H, s), 6.29 (1H, s), 4.13 (2H, s), 3.80 (3H, s), 2.88 (6H, s). (1H, d, J = 8.4 Hz).

13


C NMR (101 MHz, CD3CN): δ =

Page 9 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


130.1, 129.3, 128.1, 123.4, 123.3, 118.8, 117.4, 115.2, 44.7, 38.1, 35.8. TOF-HRMS: Calcd. For [C16H19N5O2S]+ 345.1259; Found 346.1335 (M++ 1).

3. Results and Discussion

Scheme 2. The synthesis route of target compounds 1 and 2. The synthesis schemes for the target probes 1 and 2 are shown in scheme 2. Using dansyl chloride as the starting material, the key precursor 3 was firstly prepared using a method previously described in the literature. Probe 1 was then obtained by a click reaction between 3 and 1-azidohexadecane (4) in a DMF solution. In addition, the analogous compound 2 was prepared by a similar method. The chemical structures of 1 and 2 were well characterized by analytical techniques (1H NMR, 13C NMR, and ESI-MS spectra, supporting information).



Figure 1. (a) Fluorescence emission changes of probe 1 (20 µM) with the addition of various amounts of Hg2+ in the aqueous solution, Inset: photo of the emission of probe 1 before and after the addition of 1.0 equivalent of Hg2+. (b) Emission intensity of probe 1 at 500 nm versus the number of equivalents of Hg2+.

Next, the photophysical properties of probes 1 and 2 were tested. Probe 1 showed a typical dansyl-based absorption at 342 nm in pure aqueous solution containing 0.5% DMSO co-solvent and a strong green emission with its maximum wavelength at 500 nm. However, upon the addition of Hg2+, the absorption of probe 1 changed barely (Figure S1). In contrast, the addition of a small amount of Hg2+ led to a significant quenching response in the emission of 1 (80% quenching) with a blue shift from 500 nm to 476 nm, which could be observed in the change of the fluorescence of the solution from strong green to dark blue (Figure 1). This large change in the fluorescence indicated that coordination between 1 and Hg2+ had taken place, possibly via the sulfonamide and triazole donors. Consequently, the fluorescence of probe 1 was quenched due to the heavy atom or spin-orbit coupling effects. The probable binding mode between probe 1 and Hg2+ was then analyzed by using the fluorescence spectroscopy. A 1:1 stoichiometry was observed for the host-guest complex 1-Hg2+ using the continuous variation method (Job’s plot, Figure S2). With the emission titration data, the binding constant for 1-Hg2+ complexation was found to be 7.5×105 M‒1 (Figure S3) by using the Benesi-Hildebrand equation.


Page 10 of 28

Page 11 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 2. (a) Fluorescence emission of probe 1 (20 µM) before and after 1.0 equivalent addition of metal ions in the aqueous solution. (b) The bar diagram showing the change in the emission intensity of probe 1 recorded at 500 nm upon addition of metal anions. a: Hg2+, b: Cu2+, c: Zn2+, d: Cd2+, e: Pb2+, f: Cr3+, g: Ca2+, h: Ni2+, i: Fe2+, j: Co2+, k: Ag+, l: Mg2+, m: Fe3+.

Under the same conditions used for Hg2+, the fluorescence recognition ability of 1 towards other metal ions (Cu2+, Zn2+, Cd2+, Pb2+, Cr3+, Ca2+, Ni2+, Fe2+, Co2+, Ag+, Mg2+, and Fe3+) was also investigated (Figure 2). Slight fluorescence quenching of 1 was observed in the presence of Cu2+, with negligible fluorescence change occurring upon addition of the other tested metal ions. Thus, probe 1 displayed a high fluorescence selectivity towards Hg2+ over several tested metal ions, including the possible interferents Cd2+, Cu2+, and Ag+ ions.



Figure 3. The 1H NMR spectra of probe 1 recorded with various amounts of Hg2+ in CD3CN.

The recognition capability of probe 1 for Hg2+ was also investigated using a 1H NMR titration experiment (Figure 3). In CD3CN solution, the sulfonamide proton, Ha, and the proton at the 5position of the triazole ring, Hb, of 1 were located at 6.26 ppm and 7.15 ppm, respectively. When a small amount of Hg2+ was added (0.5 equivalents), these two protons showed large downfield shifts, with ∆δ values of 0.79 ppm and 0.80 ppm for Ha and Hb, respectively. This result indicated that the two N donors from the triazole ring and the sulfonamide group chelate the Hg2+ center to form a stable five-membered ring. Thus, the resulting coordination increases the electron withdrawing ability of the sulfonamide and the triazole groups and causes the large downfield shift of the attached protons. The highly sensitive Hg2+ sensing of the probe 1 in pure aqueous solution is very interesting and could possibly be related to the incorporation of the long hydrophobic cetyl chain into this


Page 12 of 28

Page 13 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


system. To verify this assumption, the metal ion recognition ability of an analogous compound with a short methyl chain, 2, was also investigated (Figure S4). Compound 2 scarcely showed any change in fluorescence when 1.0 equivalent of Hg2+ or other tested metal ions were added in the aqueous solution. Thus, the long cetyl chain was confirmed to play a key role in improving the sensing ability of probe 1, possibly via inducing the self-aggregation of 1 in the aqueous solution.

Figure 4. (a) Photograph of the Tyndall effect of probes 1 and 2 in aqueous solution. (b) Data from the surface tension (γ) experiment of 1 recorded in the aqueous solution. (c) TEM image and, (d) DLS measurements of probe 1 (20 µM) in the aqueous solution.



The self-aggregation behavior of probe 1 was then investigated using a simple Tyndall effect experiment (Figure 4a). At the tested concentration (20 µM) in aqueous solution, probe 1 showed a strong Tyndall phenomenon, which was retained upon the addition of Hg2+. In contrast, no Tyndall phenomenon was observed for probe 2 under the same conditions. This result supported the fact that probe 1 can form nanoaggregates in the aqueous solution. The critical aggregation concentration (CMC) of probe 1 was observed as 7.86 µM by a surface tension (γ) experiment (Figure 4b); this concentration was found to be well below that was used in the Tyndall effect experiment (20 µM). The nanoaggregation of 1 was further confirmed by the dynamic light scattering (DLS) and transmission electron microscopy (TEM) measurements (Figure 4c and 4d). DLS results revealed that probe 1 self-assembles into nanoaggregates with an average diameter of 120 nm in the aqueous solution, while the TEM experiment showed sphere-like aggregates with diameters of 20‒50 nm in the solid state. Additionally, the self-assembled nanoaggregates were retained upon the addition of Hg2+. The mean diameters of 1 and the in situ generated 1Hg2+ ensemble measured by DLS was very similar. Based upon the above results, we proposed a possible binding model between probe 1 and Hg2+, as depicted in Scheme 1. First, the amphiphilic probe 1 self-assembles to form sphere-like nanoaggregates in the aqueous solution, where the hydrophilic cetyl chain pointing towards the inside, and the hydrophilic metal ions donors oriented outward. Upon the addition of Hg2+ ions, 1:1 1-Hg2+ complexes form on the outer surface of the nanoaggregates via the triazole and sulfonamide donors of probe 1. Thus, fluorescence quenching occurs through energy transfer from the heavy atom Hg2+ at the nano-interface to the probe. Due to the confinement and preorganization of the molecules in the nanointerface, probe 1 can strongly bind with Hg2+ in the aqueous solution.


Page 14 of 28

Page 15 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 5. (a) The change in fluorescence emissions of probe 1 (20 µM) in the presence of tested metal ions (Cu2+, Zn2+, Cd2+, Pb2+, Cr3+, Ca2+, Ni2+, Fe2+, Co2+, Ag+, Mg2+, Fe3+) and Hg2+ in aqueous solution. (b) The fluorescence changes I1 ‒ I1-Hg of probe 1 (20 µM) upon 1.0 equivalent addition of Hg2+ at different pH values.

Next, we performed the competition experiments of probe 1 for Hg2+ in the presence of other tested metal ions (Figure 5a). The presence of the other miscellaneous competitive metal ions scarcely induced any change in the emission response compared to Hg2+ alone. In addition, the sensing ability of probe 1 toward Hg2+ among other metal ions in Tris-HCl (1 mM, pH 7.2) buffer solution were also investigated, which gives almost the same results as that in pure water solution, indicating that the ionic strength of solution barely influences the recognition ability of 1. Furthermore, the sensing ability of 1 toward Hg2+ at different pH values was also monitored. Probe 1 showed satisfactory sensing response over a pH range from 4 to 11 (Figure 5b). Therefore, the current probe can detect Hg2+ in physiological conditions, which could be the advantageous property for further cell-based studies.



Figure 6. Emission spectra (a) and a bar graph representing the fluorescence at 500 nm (b) of probe 1 (20 µM) upon addition of various amino acids in the aqueous solution. a: Blank, b: Met, c: Asn, d: Phe, e: Arg, f: Ala, g: Lys, h: Hcy, i: Val, j: Trp, k: Asp, l: His, m: Gly, n: GSH, o: Cys, p: Try, q: Glu, r: Lue.

Considering the crucial roles of thiol-containing amino acids in the biological systems, and their high binding ability toward Hg2+ ions, the utility of the 1-Hg2+ assembly as a secondary sensor for the selective recognition of amino acids were also tested. Figure 6 shows the changes in fluorescence emisssion of the 1-Hg2+ complex upon the addition of 17 different amino acids (Cys, GSH, Hcy, Glu, Arg, Phe, Val, Tyr, Asn, Gly, Trp, Asp, His, Ala, Thr, Lys, Met, and Leu) in aqueous solution. The addition of the thiol-containing amino acids Hcy, Cys, and GSH significantly enhanced the fluorescence intensity of 1-Hg2+, while the other amino acids didn’t induce any noticeable change in the emission spectra of the 1-Hg2+ complex. Thus, the 1-Hg2+ complex was successfully utilized to detect thiol-containing amino acids via a fluorescence turnon response. In addition, the fluorescence changes of 1-Hg2+ with different anions (F‒, Cl‒, Br‒, I‒, CO32‒, SO42‒, AcO‒, H2PO4‒, HP2O73‒, ADP, AMP, ATP, UTP, GTP) and reactive oxygen species (H2O2, HOCl, ONOO‒, O2‒·, HO·) were also investigated. However, no response was observed (Fig. S5).


Page 16 of 28

Page 17 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 7. (a) Emission spectra of 1-Hg2+ (20 µM) recorded upon addition of various amounts of Cys in the aqueous solution. (b) Emission intensity of 1-Hg2+ at 500 nm versus the number of equivalents of Cys.

The fluorescence titration of 1-Hg2+ toward Cys is shown in Figure 7. With increase in the concentration of Cys, the fluorescence intensity of 1-Hg2+ gradually increased and became saturated when the concentration of Cys reached about 1 equivalent. The final emission intensity was nearly identical to that of 1, indicating that Cys could release 1 from the 1-Hg2+ complex, according to the following equation: 1-Hg2+ + Cys → 1 + Cys -Hg2+. A 1:1 stoichiometric ratio between 1-Hg2+ and Cys was determined by Benesi–Hildebrand method and the binding constant of 1-Hg2+ and Cys was obtained as 1.25×105 M‒1. Further, the detection limit (LOD) of 1-Hg2+ for Cys was observed as 10.6 nM (Figure S6) based on 3σ/k (σ = 1.12, k = 3.15 × 108) method. The emission titrations of 1-Hg2+ toward GSH and Hcy were also investigated (Figure S7‒S10). Similar binding modes with high binding constants (8.58 × 104 M‒1 and 8.26 × 105 M‒1) and low LOD values (5.6 nM and 10.0 nM) were obtained. Compared with the previously reported fluorescence-complex-based probes for biothiol detection (Table 1), the present probe 1-Hg2+ showed superior binding constants, lower LOD, and aqueous working medium. Table 1 Comparison of previously reported complexes for the detection of GSH, Cys and Hcy.



Page 18 of 28

LOD (µM) Fluorophore

Media

Refs GSH

Cys

Hcy

Pyrene-Cu2+

HEPES−DMSO, 95:5

0.16

‒

‒

47

Murexide-Hg2+

PBS, 100%

0.01

0.02

0.04

48

Fluorescein-Cu2+

HEPES, 100%

0.024

0.12

0.036

49

Benzothiazole- Cu2+

CH3CN-PBS, (1:9)

0.29

0.14

0.19

50

Aldazine- Cu2+

THF:HEPES, (1:1)

2.2

1.5

1.8

51

DMSO:Tris (8/2, v/v)

1.17

1.17

‒

52

H2O, 100%

0.006

0.011

0.010

ThiosemicarbazideHg2+ Dansyl-Hg2+

This work

Next, the biocompatibility of probe 1 was evaluated for the practical application in the living organisms. The cytotoxicity of probe 1 was investigated using a standard MTT assay (Figure S11). HepG-2 liver cancer cells were incubated with probe 1 solution in concentrations ranging from 0 to 40 µM for 24 h. Greater than 90% of the cells were found to be viable in the tested concentration range, indicating the no significant cytotoxicity of probe 1 to the cells under the current experimental conditions.


Page 19 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 8. Fluorescence images of liver cancer HepG-2 cells, which were pretreated with NEM (1 mM)

for 30 min: (a) co-stained with 10 µM of probe 1 and 100 nM of Mito-Tracker red; (b) upon the addition of Hg2+ (10 µM); (c) and after the addition of Cys (50 µM).

Next, the biological application of probe 1 for the detection of Hg2+ and Cys in the living cells was performed (Figure 8). To avoid the interference of intracellular thiols, the HepG-2 cells were pretreated with 1 mM N-methylmaleimide, a well-known thiol-blocking reagent.44 The cells were co-stained with probe 1 (10 µM) and commercially available dye Mito-Tracker red (100 nM) and incubated for 30 min (37 °C) in a carbon dioxide incubator (95% relative humidity with 5% CO2). Figure 8 shows that high brightness in the cytoplasm and cell membranes of the cells, indicating that probe 1 could successfully penetrate the cell. Then 10 µM Hg2+ was added to the cell medium and the cells were further incubated for 30 min (37 °C), the fluorescence signal



(green channel) of probe 1 inside the cells was significant quenched due to binding of with Hg2+ (Figure 8). Further, 50 µM Cys was added and the green fluorescence was recovered due to the release of 1 from the 1-Hg2+ complex in the living cells (Figure 8). During this period, the red channel of the control co-staining dye Mito-Tracker red shows barely any change. Thus, probe 1 was successfully demonstrated for the fluorescence imaging of intracellular Hg2+, and the resulting 1-Hg2+ complex served to detect the thiol-containing amino acids in live cells. Conclusion In this study, we have developed a novel amphiphilic dansyl-based probe (1) for sequential sensing of mercury (II) and thiol-containing amino acids. In the aqueous solution, the probe can self-assemble into sphere-like nanostructured aggregates and shows selective “on-off” fluorescence response to Hg2+ over other tested metal ions. In contrast, the analogous compound bearing a short methyl chain (2) exhibits little fluorescence change in the presence of Hg2+, which indicates that the confinement and preorganization of the molecules in a nano-interface can enhance the metal ion binding ability of the probe. Interestingly, the obtained 1-Hg2+ complex acts as an efficient fluorescence “off-on” sensor for thiol-containing amino acids, like Hcy, Cys, and GSH. The LOD values for Cys, Hcy, and GSH are found to be 10.6 nM, 10.4 nM, and 5.6 nM, respectively. Probe 1 shows minimal cytotoxicity with excellent cell permeability and capable for the fluorescence imaging of intracellular Hg2+ and Cys in live cells. Thus, we believe that the present simple and cost-effective amphiphilic probe provides a promising strategy for designing the selective probes for Hg2+ and other metal ions.

ASSOCIATED CONTENT Supporting Information


Page 20 of 28

Page 21 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Analytical characterization of probes 1 and 2, UV-Vis and fluorescence emission spectra of probes 1 and 2, Cell viability results in HepG-2 cells. AUTHOR INFORMATION ORCID Jong Seung Kim: 0000-0003-3477-1172 Qian-Yong Cao: 0000-0002-6330-5050 Seyoung Koo: 0000-0002-0620-5395 Amit Sharma: 0000-0003-2815-8208 Notes The authors declare no competing financial interest.

ACKNOWLEDGEMENTS This work was supported by the National Nature Science Foundation of China (nos. 21462027 and

21762028)

and

the

Natural

Science

Foundation

of

Jiangxi

Province

(No.

20171BAB203009), and by a CRI project (Grant No. 2018R1A3B1052702, J.S.K.) of the NRF in Korea.

REFERENCES (1)

Clarkson, T. W.; Magos, L.; Myers, G. J. The Toxicology of Mercury-Current Exposures and Clinical Manifestations. New Engl. J. Med. 2003, 349, 1731−1737.

(2)

Wolfe, M. F.; Schwarzbach, S.; Sulaiman, R. A. Effects of Mercury on Wildlife. Environ. Toxicol. Chem. 1998, 17, 146−160.

(3)

Harris, H. H.; Pickering, I. J.; George, G. N. The Chemical Form of Mercury in Fish. Science 2003, 301, 1203−1203.



(4)

Tchounwou, P. B.; Ayensu, W. K.; Ninashvili, N.; Sutton, D. Environmental Exposure to Mercury and Its Toxicopathologic Implications for Public Health. Environ. Toxicol. 2003, 18, 149−175.

(5)

Kunkel, R.; Manahan, S. E., Atomic-Absorption Analysis of Strong Heavy Metal Chelating Agents in Water and Waste Water. Anal. Chem. 1973, 45, 1465−1468.

(6)

Li, Y. K.; Xu, Y. R.; Huang, Y.; Dai, Y.; Hu, Q. F.; Yang, G. Y., Cold Vapour Generation and Atomic Fluorescence Spectrometry for the Determination of Mercury. Asian J. Chem. 2009, 21, 2893−2897.

(7)

Bings, N. H.; Bogaerts, A.; Broekaert, J. A. C., Atomic Spectroscopy. Anal. Chem. 2006, 78, 3917−3945.

(8)

Kim, H. N.; Ren, W. X.; Kim, J. S.; Yoon, J. Fluorescent and Colorimetric Sensors for Detection of Lead, Cadmium, and Mercury Ions. Chem. Soc. Rev. 2012, 41, 3210−3244.

(9)

Nolan, E. M.; Lippard, S. J. Tools and Tactics for the Optical Detection of Mercuric Ion. Chem. Rev. 2008, 108, 3443−3480.

(10) Saleem, M.; Rafiq, M.; Hanif, M. Organic Material Based Fluorescent Sensor for Hg2+: A Brief Review on Recent Development. J. Fluoresc. 2017, 27, 31−58. (11) Cao, Q-Y.; Han, Y-M.; Wang, H-M.; Xie, Y. A New Pyrenyl-Appended Triazole for Fluorescent Recognition of Hg2+ Ion in Aqueous Solution. Dyes Pigmen. 2013, 99, 798−802. (12) Li, M.; Sun, Y.; Dong, L.; Feng, Q. C.; Xu, H.; Zang, S. Q.; Mak, T. C. Colorimetric Recognition of Cu2+ and Fluorescent Detection of Hg2+ in Aqueous Media by a Dual Chemosensor Derived from Rhodamine B Dye with a NS2 Receptor. Sens. Actuators, B 2016, 226, 332−341. (13) Qu, W-j.; Gao, G-y.; Shi, B-b.; Wei, T-b.; Zhang, Y-m.; Lin, Q.; Yao, H. A Highly Selective and Sensitive Fluorescent Chemosensor for Mercury Ions Based on the Mechanism of Supramolecular Self-Assembly. Sens. Actuators, B 2014, 204, 368−374. (14) Nolan, E. M.; Lippard, S. J. Turn-On and Ratiometric Mercury Sensing in Water with a Red-Emitting Probe. J. Am. Chem. Soc. 2007, 129, 5910−5918. (15) Bhalla, V.; Tejpal, R.; Kumar, M. Rhodamine Appended Terphenyl: A Reversible “Off– On” Fluorescent Chemosensor for Mercury Ions. Sens. Actuators, B 2010, 151, 180−185.


Page 22 of 28

Page 23 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(16) Jiao, Y.; Zhang, L.; Zhou, P. A Rhodamine B-Based Fluorescent Sensor Toward Highly Selective Mercury (II) Ions Detection. Talanta 2016, 150, 14−19. (17) Huang, W.; Song, C.; He, C.; Lv, G.; Hu, X.; Zhu, X.; Duan, C. Recognition Preference of Rhodamine-Thiospirolactams for Mercury(II) in Aqueous Solution. Inorg. Chem. 2009, 48, 5061−5072. (18) Guo, Z.; Zhu, W.; Shen, L.; Tian, H. A Fluorophore Capable of Crossword Puzzles and Logic Memory. Angew. Chem. Int. Ed. 2007, 46, 5549−5553. (19) Kim, H. N.; Lee, M. H.; Kim, H. J.; Kim, J. S.; Yoon, J. A New Trend in RhodamineBased Chemosensors: Application of Spirolactam Ring-Opening to Sensing Ions. Chem. Soc. Rev. 2008, 37, 1465−1472. (20) Klymchenko, A. S. Solvatochromic and Fluorogenic Dyes as Environment-Sensitive Probes: Design and Biological Applications. Acc. Chem. Res. 2017, 50, 366−375. (21) Yang, M.; Sun, M.; Zhang, Z.; Wang, S. A Novel Dansyl-Based Fluorescent Probe for Highly Selective Detection of Ferric Ions, Talanta 2013, 105, 34‒39. (22) Fiorani, G.; Selva, M.; Perosa, A.; Benedetti, A.; Enrichi, F.; Licence, P.; Easun, T. L. Luminescent Dansyl-Based Ionic Liquids from Amino Acids and Methylcarbonate Onium Salt Precursors: Synthesis and Photobehaviour, Green Chem. 2015, 17, 538–550. (23) Lakowicz J. R. Principle of Fluorescence Spectroscopy, Energy Transfer. Springer: Boston, MA, 2006; p. 443−475. (24) Aliberti, A.; Vaiano, P.; Caporale, A.; Consales, M.; Ruvo, M.; Cusano, A. Fluorescent Chemosensors for Hg2+ Detection in Aqueous Environment. Sens. Actuators, B 2017, 247, 727−735. (25) Neupane, L. N.; Kim, J. M.; Lohani, C. R.; Lee, K. H. Selective and Sensitive Ratiometric Detection of Hg2+ in 100% Aqueous Solution with Triazole-Based Dansyl Probe. J. Mater. Chem. 2012, 22, 4003−4008. (26) Dhir, A.; Bhalla, V.; Kumar, M. Ratiometric Sensing of Hg2+ Based on the Calix [4] arene of Partial Cone Conformation Possessing a Dansyl Moiety. Org. Lett. 2008, 10, 4891−4894. (27) Talanova, G. G.; Talanov, V. S. Dansyl-Containing Fluorogenic Calixarenes as Optical Chemosensors of Hazardous Metal Ions: a mini-review. Supramol. Chem. 2010, 22, 838−852.



(28) Muwal, P. K.; Pandey, S.; Pandey P. S. A Novel Dansyl-Appended Bile Acid Receptor for Preferential Recognition of Hg2+. RSC Adv. 2014, 4, 21531−21534. (29) Tharmaraj, V.; Pitchumani, K. An Acyclic, Dansyl Based Colorimetric and Fluorescent Chemosensor for Hg (II) via Twisted Intramolecular Charge Transfer (TICT). Anal. Chim. Acta 2012, 751, 171−175. (30) Hatai, J.; Pal, S.; Jose, G. P.; Bandyopadhyay, S. Histidine Based Fluorescence Sensor Detects Hg2+in Solution, Paper Strips, and in Cells. Inorg. Chem. 2012, 51, 10129−10135. (31) Kleinman, W. A.; Richie, J. P. Status of Glutathione and Other Thiols and Disulfidesin Human Plasma. Biochem. Pharmacol. 2000, 60, 19−29. (32) Lee, M. H.; Sharma, A.; Chang, M. J.; Lee, J.; Son, S.; Sessler, J. L.; Kang, C.; Kim, J. S., Fluorogenic Reaction-based Prodrug Conjugates as Targeted Cancer Theranostics. Chem. Soc. Rev. 2018, 47, 28−52. (33) Lin, J.; Lee, I. M.; Song, Y.; Cook, N. R.; Selhub, J.; Manson, J. E.; Buring, H. E.; Zang, S. M. Plasma Homocysteine and Cysteine and Risk of Breast Cancer in Women. Cancer Res. 2010, 70, 2397−2405. (34) Reddie, K. G.; Carroll, K. S. Expanding the Functional Diversity of Proteins through Cysteine Oxidation. Curr. Opin. Chem. Biol. 2008, 12, 746−754. (35) Jung, H. S.; Chen, X.; Kim, J. S.; Yoon, J. Recent Progress in Luminescent and Colorimetric Chemosensors for Detection of Thiols. Chem. Soc. Rev. 2013, 42, 6019−6031. (36) Yin, C.; Huo, F.; Zhang, J.; Martínez-Máňez, R.; Yang, Y.; Lu, H.; Li, S. A Colorimetric and Near-Infrared Fluorescent Probe for Biothiols and Its Application in Living Cells. Chem. Soc. Rev. 2013, 42, 6032−6059. (37) Niu, L.Y.; Chen, Y. Z.; Zheng, H. R.; Wu, L. Z.; Tung, C. H.; Yang, Q. Z. Design Strategies of Fluorescent Probes for Selective Detection among Biothiols. Chem. Soc. Rev. 2015, 44, 6143−6160. (38) Lim, S. Y.; Hong, K. H.; Kim, D. I.; Kwon, H.; Kim, H. J. Tunable Heptamethine–Azo Dye Conjugate as an NIR Fluorescent Probe for the Selective Detection of Mitochondrial Glutathione over Cysteine and Homocysteine. J. Am. Chem. Soc. 2014, 136, 7018−7025. (39) Niu, L.Y.; Guan, Y. S.; Chen, Y. Z.; Wu, L. Z.; Tung, C. H.; Yang, Q. Z. BODIPY-Based Ratiometric Fluorescent Sensor for Highly Selective Detection of Glutathione over Cysteine and Homocysteine. J. Am. Chem. Soc. 2012, 134, 18928−18931.


Page 24 of 28

Page 25 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(40) Liu, J.; Sun, Y. Q.; Huo, T.; Zhang, H.; Wang, L.; Zhang, P.; Song, D.; Shi, Y.; Guo, W. Simultaneous Fluorescence Sensing of Cys and GSH from Different Emission Channels. J. Am. Chem. Soc. 2014, 136, 574−577. (41) Han, X.; Song, X.; Yu, F.; Chen, L. A Ratiometric Fluorescent Probe for Imaging and Quantifying Anti-Apoptotic Effects of GSH under Temperature Stress. Chem. Sci. 2017, 8, 6991−7002. (42) He, L.; Yang, X.; Xu, K.; Kong, X.; Lin, W. A Multi-Signal Fluorescent Probe for Simultaneously Distinguishing and Sequentially Sensing Cysteine/Homocysteine, Glutathione, and Hydrogen Sulfide in Living Cells. Chem. Sci. 2017, 8, 6257−6265. (43) Lee, J. H.; Sharma, A.; Jang, J. H.; Shin, W. S.; Lee, J. H.; Kim, J. S., Real time OFF-ON Monitoring of Gluthathione (GSH) in Living Cell. J. Incl. Phenom. Macro. 2015, 82, 117−122. (44) Ren,T.-B.; Zhang, Q.-L; Su, D.; Zhang, X.-X.; Yuan, L.; Zhang, X.-B. Detection of Analytes in Mitochondria without Interference from Other Sites Based on an Innovative Ratiometric Fluorophore. Chem. Sci. 2018, 9, 5461−5466. (45) Sedgwick, A. C.; Gardiner, J. E.; Kim, G.; Yevglevskis, M.; Lloyd, M. D.; Jenkins, A. T. A.; Bull, S. D.; Yoon, J.; James, T. D. Long-Wavelength TCF-Based Fluorescence Probes for the Detection and Intracellular Imaging of Biological Thiols. Chem. Commun. 2018, 54, 4786−4789. (46) Li, Y.; Liu, W.; Zhang, H.; Wang, M.; Wu, J.; Ge, J.; Wang, P. Dual-Emission Channels for Simultaneous Sensing of Cysteine and Homocysteine in Living Cells. Chem. Asian J. 2017, 12, 2098−2103. (47) Yan, C.; Guo, Z.; Shen, Y.; Chen, Y.; Tian, H.; Zhu, W.-H. Molecularly Precise SelfAssembly of Theranostic Nanoprobes within a Single-Molecular Framework for in vivo Tracking of Tumor-Specific Chemotherapy. Chem. Sci. 2018, 9, 4959−4969. (48) Zhou, Y.; Yoon, J. Recent Progress in Fluorescent and Colorimetric Chemosensors for Detection of Amino Acids. Chem. Soc. Rev. 2012, 41, 52−67. (49) Jung, J. M.; Kim, C.; Harrison, R. G. A Dual Sensor Selective for Hg2+ and Cysteine Detection. Sens. Actuators, B 2018, 255, 2756−2763.



(50) Hu, Y.; Heo, C. H.; Kim, G.; Jun, E. J.; Yin, J.; Kim, H. M.; Yoon, J. One-Photon and Two-Photon Sensing of Biothiols Using a Bis-Pyrene-Cu(II) Ensemble and Its Application to Image GSH in the Cells and Tissues. Anal. Chem. 2015, 87, 3308−3313. (51) Zhao, W.; Sun, M.; Lei, T.; Liu, X.; Zhang, Q.; Zong, C. An Indicator-Displacement Assay Based on the Murexide-Hg2+ System for Fluorescence Turn-On Detection of Biothiols in Biological Fluids. Sens. Actuators, B 2017, 24, 90−95. (52) Fu, Z. H.; Yan, L. B.; Zhang, X.; Zhu, F. F.; Han, X. L.; Fang, J.; Wang, Y. W.; Peng, Y. A Fluorescein-Based Chemosensor for Relay Fluorescence Recognition of Cu(II) Ions and Biothiols in Water and Its Applications to a Molecular Logic Gate and Living Cell Imaging. Org. Biomol. Chem. 2017, 15, 4115−4121. (53) Shen, Y.; Zhang, X.; Zhang, C.; Zhang, Y.; Jin, J.; Li, H. A Simple Fluorescent Probe for the Fast Sequential Detection of Copper and Biothiols Based on a Benzothiazole Derivative. Spectrochim. Acta, Part A 2018, 191, 427−434. (54) Wang, Y.; Zhang, Z.; Meng, Q.; He, C.; Zhang, R.; Duan, C. A New Ensemble Approach Based Chemosensor for the Reversible Detection of Bio-Thiols and Its Application in Live Cell Imaging. J. Lumin. 2016, 175, 122−128. (55) You, G. R.; Lee, S. Y.; Lee, J. J.; Kim, Y. S.; Kim, C. Sequential Detection of Mercury(II) and Thiol Containing Amino Acids by a Fluorescent Chemosensor. RSC Adv. 2016, 6, 4212−4220. (56) Yu, G.; Jie, K.; Huang, F. Supramolecular Amphiphiles Based on Host–Guest Molecular Recognition Motifs. Chem. Rev. 2015, 115, 7240−7303. (57) Ren, C.; Zhang, J.; Chen, M.; Yang, Z. Self-Assembling Small Molecules for the Detection of Important Analytes. Chem. Soc. Rev. 2014, 43, 7257−7266. (58) Ma, X.; Zhao, Y. Biomedical Applications of Supramolecular Systems Based on Host– Guest Interactions. Chem. Rev. 2015, 115, 7794−7839. (59) Peng, H.; Niu, L.; Chen, Y.; Wu, L.; Tung, C.; Yang, Q. Biological Applications of Supramolecular Assemblies Designed for Excitation Energy Transfer. Chem. Rev. 2015, 115, 7502−7542. (60) Zhang, X.; Wang, K.; Liu, M.; Zhang, X.; Tao, L.; Chen, Y.; Wei, Y. Polymeric AIE-Based Nanoprobes for Biomedical Applications: Recent Advances and Perspectives. Nanoscale 2015, 7, 11486−11508.


Page 26 of 28

Page 27 of 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(61) Zhu, J-H.; Yu, C.; Chen, Y.; Shin, J.; Cao, Q-Y.; Kim, J. S. A Self-Assembled Amphiphilic Imidazolium-Based ATP Probe. Chem. Commun. 2017, 53, 4342−4345. (62) Kim, I.; Lee, N. E.; Jeong, Y. J.; Chung, Y. H.; Cho, B. K.; Lee, E. Micellar and Vesicular Nanoassemblies of Triazole-Based Amphiphilic Probes Triggered by Mercury (II) Ions in a 100% Aqueous Medium. Chem. Commun. 2014, 50, 14006−14009. (63) Chi, X.; Yu, G.; Shao, L.; Chen, J.; Huang, F. A Dual-Thermoresponsive Gemini-Type Supra-Amphiphilic

Macromolecular

[3]

Pseudorotaxane

Based

on

Pillar

[10]

Arene/Paraquat Cooperative Complexation. J. Am. Chem. Soc. 2016, 138, 3168−3174. (64) Nie, K.; Dong, B.; Shi, H.; Liu, Z.; Liang, B. Diketopyrrolopyrrole Amphiphile-Based Micelle-Like Fluorescent Nanoparticles for Selective and Sensitive Detection of Mercury (II) Ions in Water. Anal. Chem. 2017, 89, 2928−2936. (65) Li, C-T.; Xu, Y-L.; Yang, J-G.; Chen, Y.; Kim, H. S.; Cao, Q-Y.; Kim, J. S. Pyrophosphate-Triggered Nanoaggregates with Aggregation-Induced Emission. Sens. Actuators, B 2017, 251, 617−623. (66) Lau, Y. H.; Rutledge, P. J.; Watkinson, M.; Todd, M. H. Chemical Sensors that Incorporate Click-Derived Triazoles. Chem. Soc. Rev. 2011, 40, 2848−2866. (67) Schulze, B.; Schubert, U. S. Beyond Click Chemistry–Supramolecular Interactions of 1,2,3-Triazoles. Chem. Soc. Rev. 2014, 43, 2522−2571. (68) Liu, L.-N.; Tao, H.; Chen, G.; Chen, Y.; Q.-Y. Cao, An Amphiphilic Pyrene-Based Probe for Multiple Channel Sensing of Mercury Ions, J. Lumin. 2018, 203, 189–194. (69) Wong, W. Y.; Poon, S. Y.; Lin, M-F.; Wong, W. K. Fluorescent Ethenyl- and Ethynyldimesitylboranes

Derived

from

5-(Dimethylamino)-N-(prop-2-ynyl)naphthalene-1-

sulfonamide. Aust. J. Chem. 2007, 60, 915−922. (70) Mishra, R.; Pandey, S.; Trivedi, S.; Pandey, S.; Pandey, P. S. Synthesis and Properties of L-valine Based Chiral Long Alkyl Chain Appended 1,2,3-Triazolium Ionic Liquids, RSC Adv. 2014, 4, 33478−33488.



Page 28 of 28

Graphical Abstract

Hg2+

Aqueous medium

Bithiols Hg 2+


Multifunctional Fluorescent Nanoprobe for Sequential Detections of

Recommend Documents