Aggregates-Based Boronlectins with Pyrene as Fluorophore

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Aggregates-based Boronlectins with Pyrene as Fluorophore: Multichannel Discriminative Sensing of Monosaccharides and their Applications Xiao-Tai Zhang, Shu Wang, and Guo-wen Xing ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.6b01940 • Publication Date (Web): 25 Apr 2016 Downloaded from http://pubs.acs.org on May 1, 2016

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ACS Applied Materials & Interfaces

Aggregates-based Boronlectins with Pyrene as Fluorophore: Multi-channel Discriminative Sensing of Monosaccharides and their Applications Xiao-tai Zhang,† Shu Wang‡ and Guo-wen Xing*† †

Department of Chemistry, Beijing Normal University, Beijing 100875, China

‡

Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China

ABSTRACT: Four-channel fluorescence assay towards six monosaccharides was achieved by employing two novel pyrenefunctionalized boronlectins with flexible diboronic acid as receptors. The effects of pH values and aging time on the sensor properties were thoroughly evaluated by UV-Vis, fluorescence spectroscopy and dynamic light scattering. We find that the fluorescence relative ratios were highly correlated with analyte concentrations at μM level. The flexibility of the receptors was perceived as an indispensable factor to produce diverse fluorescence signals towards different monosaccharides. Most importantly, integration of four fluorescence channels derived from the two sensors enables an excellent discrimination for all tested monosaccharides at a certain concentration or a concentration range via linear discriminant analysis (LDA). It is proposed that the multiple flexible linkers in the boronlectins could increase their self-adaptive capacity for different analytes, and facilitate the formation of stable boronlectin-sugar aggregate assemblies. In addition, practical sensing of glucose in the simulative blood and urine was illustrated to be feasible in the presence of interferences at physiological concentrations. KEYWORDS: boronlectin, pyrene, monosaccharide, aggregates, sensor

INTRODUCTION As part and parcel of organisms, saccharides are actively involved in multifarious biological events1-2: glucose and its multimers are of great importance in supplying primary energy for basic survival; cellulose serves as the framework of plants; deoxyribose is one of the building blocks of DNA; etc. Besides, oligosaccharide motifs that bear specific sequences are over-expressed on the surface of malignant cells, and as a result, corresponding abnormal glycosylation process can be perceived as a manifestation of cancer.3-4 Based on the profound understanding of biological significances of various saccharides, massive efforts have been devoted to the design and construction of sensing systems which enable the specific capture towards a certain kind of saccharide.5-8 Apparent structural characteristics of saccharides, namely abundant in saturated aliphatic C-H bonds and hydroxy groups, have aroused researchers’ inspiration to develop several kinds of biomimetic lectins with rigid macropolycycles. The synthetic receptors are capable of encapsulating oligosaccharides such as glucoside, β-GlcNAc or cellobioside with the aid of CH-π interaction and hydrogen bonds.9-13 Nevertheless, it was difficult to balance the water-solubility of sensors and high affinities with analytes, and the tedious synthetic routes also confine the practical applications. Compared with aforementioned acceptors featuring non-covalent

interactions, the boronic acid-based supramolecular systems, which can covalently and reversibly bind with cis1,2- or 1,3-diol moieties to form five- or six-membered cyclic boronic esters,14-17 have attracted more attentions due to the polytropic design philosophy and facile synthesis. It is worth noting that a single boronic acid moiety exhibits much higher affinity with fructose than other monosaccharides.15 For the purpose to broaden the substrates of sensing, especially to attach importance to glucose which is indispensable for normal operation of organisms, two strategies have been exploited in general. i) Introduction of two boronic acid moieties in a molecule is proved to be feasible in selective sensing glucose through multivalent interaction.18-21 Optimization of the spatial distance and relative orientation between the two binding sites can be achieved via modular approach20 or computer-guided design.19 ii) The systems based on boronic acidinvolved supramolecular assembly are another hotspot in the area of saccharides sensing, which were functionalized with “exogenous” fluorescent indicators21-25 or “endogenic” fluorophore such as pyrene26-30 and tetraphenylethene31. In addition, the performance of the complexes resulted from monoboronic acid receptors and cyclodextrins was extensively investigated as well32-34. Additionally, graphene oxide, hydrogel, or silica gels can also be modified by boronic acid to form novel composite materials to detect or separate saccharides35-37.

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In the previous work, we developed a series of watersoluble cationic diboronic acids NHBAs with a novel flexible linker derived from N,N-di-2-picolylamine (DPA). A covalently-discrete anionic fluorescent dye 8hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) was used as the indicator, and discriminative sensing of mono- and disaccharides was facilely achieved by the integrated sensor array.24 Herein, we designed a pair of pyrene-functionalized flexible diboronic acids PDBA1 and PDBA2, which exhibit difference merely on the flexible aliphatic linkers between pyrenyl and DPA moiety, and the turnable methylene sites of boronic acid receptors were highlighted in purple color (Scheme 1). More importantly, introduction of pyrene fluorophore should have potential to trigger a dual-channel responses towards analytes. In fact, some kinds of pyrene-appended sensors have been reported to interact with saccharides, but most of them just focused on the monomer emission modulated by photoinduced electron transfer (PET) process,20,32,38-40 few work successfully realized the assemblyinduced excimer emission27-29 which suggested the formation of aggregates. In the current work, boronlectin compounds PDBA1 and PDBA2 share similar chemical structures with two flexible binding sites, and we found that the little structural difference would remarkably affect the multi-channel fluorescent responses during the boronlectin-sugar aggregates formation.

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failed. The negative results presumably stemmed from the spatial hindrance caused by the two groups that attached to the nitrogen atom of the secondary amine. (1)

N O

O

N

N H

N

N

DPA

OH

a)

N

PD1 HO

OH B

O

Br

N

N

B(OH) 2

b)

N

2Br

OH B OH

PDBA1

N

(2)

N

N H

DPA OH

Br

a)

b)

HO

Br N

N

N

B(OH)2

c) PD2

N

OH B

2Br

N

PDBA2

N

OH B OH

Scheme 2. Synthesis of PDBA1 and PDBA2. (1) a) DIEA, HBTU, DMF, r.t., 85%; b) THF, 65℃ reflux, 40%; (2) a) PPh3, CBr4, K2CO3, DCM, r.t., 95%; b) K2CO3, KI, CH3CN, 65℃, 86%; c) THF, 65℃ reflux, 33%. DIEA = N, N-diisopropylethylamine, HBTU = O-(benzotriazol-1-yl)N, N, N', N'-tetramethyluronium hexafluorophosphate, DMF = N, Ndimethylformamide, THF = tetrahydrofuran, DCM = dichloromethane.

Spectral characteristics of sensors

Scheme 1. Sensing system in current work.

RESULTS AND DISCUSSION Synthesis Desired diboronic acid PDBA1 was readily synthesized via two steps (Scheme 2). The precursor molecule PD1 was obtained through the reaction of commercially available 1-pyrenebutyric acid with equivalent DPA. Then, excess 2(bromomethyl)phenylboronic acid was used to achieve the quaternization of PD1 in THF, the generated crude product was purified through reversed-phase column chromatography (SiliaSphere C18) eluting with MeOH/H2O mixed solvent to afford the final product PDBA1.24 Synthesis of PDBA2 followed the similar strategy (Scheme 2). Initial molecule 1-pyrenebutanol was converted to corresponding alkyl bromide, and then interact with DPA to obtain the precursor PD2.41-42 The final procedure was identical to that in the synthesis of PDBA1. We also attempted to synthesized the target molecules PDBA1 and PDBA2 with a convergent modular method, namely 1-pyrenebutyric acid or 1-pyrenebutyl bromide was directly used to react with NHoBA in hand, but all

The UV-Vis absorption spectra of diboronic acids PDBA1 and PDBA2 were measured, and the pyrenespecific vibronic bands with maximum absorbance at 343, 327, 313 nm can be assigned to (0→0), (0→1) and (0→2) transition, respectively (Figure S1a, S1b).43-44 Molar extinction coefficients of PDBA1 and PDBA2 were calculated to be 2.97×104 and 2.58×104 M-1cm-1 respectively on the basis of linear relationships between the absorption intensity at 343 nm and the sensor concentrations (Figure 1a). In addition, we have reason to conclude that both PDBA1 and PDBA2 exhibit good water-solubility at the concentration ranges, which can be attributed to the presence of quaternary ammonium salt and boronic acid moieties. However, the spectrum of PD1 gradually became lessstructured with the appearance of a new band at 354 nm (Figure S1c), and a typical isobestic point arose at 347 nm when setting molar extinction coefficient as the dependent variable (Figure 1b), which was absent in the cases of PDBA1 and PDBA2 (Figure S2). The result indicated the aggregation behavior of PD1, which was resulted from its poor water-solubility, and the aggregating constant (Kagg) was calculated to be 3.04×105 M-1 through non-linear fitting (Figure 1b), the change of Gibbs free energy (ΔGagg, 298K) was -31.3 KJ M-1.45-46 In addition, the quite broad and unresolved bands shown in the UV-Vis absorption spectrum of PD2 at the concentration of 2 μM reflected its prominent hydrophobicity (Figure S1d). It is well known that the forms of both the boron and nitrogen centers are closely associated with the pH


(a) 0.25 A (343 nm)

0.20

Absorbance

0.20 0.15

PDBA1 PDBA2

0.16

(a) 1000

Fluorescence Intensity (a.u.)

changes of the media. Under alkaline conditions, the initial sp2 hybridized boronic acids are readily converted into sp3 hybridized anionic boronates with an extra hydroxy attached to the boron atom, whereas the nitrogen atom will quickly be protonated under acidic conditions. Ionization behaviors will affect the aggregating process to some extent to bring about certain electronic effects. Fluorescence emissions towards PDBA1 and PDBA2 in monomer and excimer channels were investigated at a broad pH range (Figure S3). It was found that the diboronic acids exhibited an obvious π-π interaction-induced excimer emission (528 nm for PDBA1, 488 nm for PDBA2) from pH 5.0 to 9.0 (Figure 2), and we speculated that a massive amount of anhydride may generate which enable pyrene fluorophores to close mutually. Interestingly, the monomer emission of PDBA1 (381 nm) enhanced dramatically along with the increased pH, but that of PDBA2 (381 nm) possessed an opposite trend. To weaken the effects of sensors themselves in the absence of analytes, pH 10.0 was considered to be the ideal condition at which PDBA1 and PDBA2 showed inconspicuous excimer emission background. Additionally, an alkaline pH value also favors the interaction between boronic acid and diol.5,47-48

PDBA1-Monomer (381 nm) PDBA1-Excimer (528 nm)

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4

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(b)

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pH

0.08

Figure 2. pH profiles of monomer emission and excimer emission towards a) PDBA1 and b) PDBA2. [PDBA1] = [PDBA2] = 100 μM, λex = 327 nm, slitex = slitem = 10 nm.

0.04 3

9

PDBA2-Monomer (381 nm) PDBA2-Excimer (488 nm)

700

R = 0.9994

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8

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0.12

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Titration experiments PDBA1 PDBA2

0.05 0.00 250

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Wavelength (nm)

(b) 4

4x10

ε 343 nm (M-1cm-1)

36000 33000 30000

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24000

4

2x10

2

3

4 5 6 -6 [PD1] (10 M)

2uM 4uM 6uM

4

1x10

0 300

7

350

400

450

3uM 5uM 7uM

500

Wavelength (nm)

Figure 1. (a) UV-Vis absorption spectra of diboronic acids PDBA1 and PDBA2 at 7 μM in carbonate buffer (50 mM, pH 10.0) containing 1% (v/v) DMSO. Inset: plots of UV-Vis absorption at 343 nm. (b) UVVis absorption spectra of PD1 with ɛ (molar extinction coefficient) as the dependent variable. Inset: plot of ɛ at 343 nm.

In the absence of analytes, the monomer emission with high intensity at 381 nm of PDBA1 was observed. Addition of glucose triggered a novel and typical dual-channel ratiometric response with an isostilbic point at 437 nm, i.e. the excimer emission at 528 nm increased with decreasing monomer emission (Figure 3a, 3b). The system reached saturation when the concentration of glucose was up to about 500 µM, and about 24-fold enhancement of fluorescence ratio (I528 nm/I381 nm) was afforded (Figure S4). Existence of considerable excimer emission confirmed the formation of aggregates in the presence of glucose. In addition, an excellent linear relationship between the intensity ratios and glucose concentrations from 10 to 100 µM was obtained (Figure S4), which would facilitate the sensing of glucose in practical samples. Corresponding UV-Vis absorption spectra of PDBA1 upon addition of glucose were also measured (Figure 3c). The isobestic points at 331 nm and 336 nm indicated inconsistence of decrease at 327 nm and 343 nm. Variation or reversal of the relative intensity of (0→0) and (0→1) vibronic bands always relates to the π-π stacking in pyrene- or perylene diimide (PDI)-involved systems.43-44,49-51 In the present case, the ratio of absorption at 343 nm and 327 nm decreased with the increasement of glucose concentration, which offered evidence towards the formation of aggregates.



ing, even though the glucose concentration was 10 mM (Figure S5c). Therefore, aging after the preparation of samples is an indispensable procedure in practical testing.

(a) [Glu] 0 - 500 µM

400

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0 350

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Wavelength (nm)

(b) Fluorescence Intensity (a.u.)

800

280

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200 220 100 200 0 0

Monomer (381 nm) Excimer (528nm)

100

200

300

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500

Aging Time (min) Figure 4. Time-dependent excimer emission and effective particle diameter at pH 10.0. [PDBA1] = 100 μM, [Glu] = 500 μM, λex = 327 nm, slitex = slitem = 10 nm. Particle size was measured by dynamic light scattering.

600

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0 0

10

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-5

[Glucose] (10 M)

(c)

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Effective Diameter (nm)

600

Excimer Intensity (528 nm) (a.u.)


800

[Glu] 0 - 500 µM 3.5

1.40

3.0

1.36 A343nm/A327nm

Absorbance

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2.5 2.0 1.5

1.32 1.28 0

10

20

30

40

50

-5

[Glucose] (10 M)

1.0 0.5 0.0 300

350

400

450

500

Wavelength (nm) Figure 3. (a) Fluorescence emission spectra of PDBA1 upon addition of glucose at pH 10.0 in carbonate buffer (50 mM) containing 1% (v/v) DMSO. [PDBA1] = 100 μM, λex = 327 nm, slitex = slitem = 10 nm, aging time = 3 h. (b) Concentration-dependent fluorescence responses of monomer and excimer emission. (c) UV-Vis absorption spectra of PDBA1 upon addition of glucose. Inset: plot of absorption ratios at 343 nm and 327 nm.

In order to obtain satisfying fluorescence responses, aging process should be taken into account. Formation of aggregates involving PDBA1 and glucose was highly dependent on time, both the excimer emission and effective particle diameter increased gradually when prolonged aging time, and two sets of signals reached the maximum after standing for 3 h (Figure 4, Figure S5a, S6). The timedependent absorption spectra (Figure S5b) closely resembled the case of titration experiment with glucose. Negligible fluorescence responses were observed without ag-

Next, titration experiments of diboronic acids with various monosaccharides were performed systematically and comprehensively (Figure S7-S17). The ratiometric responses of various monosaccharides based on the formation of aggregates were obtained for the first time, except for glucose which had been selectively identified via a pyrene-functionalized monoboronic acid.29 Relative ratio, which refers to the quotient of ratios between excimer emission and monomer emission in the presence (p)/absence (a) of analyte (i.e. [Iexcimer/Imonomer]p / [Iexcimer /I monomer ] a ), was found to be highly concentrationdependent (Figure 5). Compared with the most reported unimolecular boronic acid receptors for sensing saccharides at mM levels,21,25,52-60 PDBA1 and PDBA2 exhibited much higher sensitivities towards monosaccharides since they gave rise to sufficient fluorescence responses for analytes at μM level. Besides ribose, the monomer emission of PDBA1 was decreased in the process of titration (Figure 3, S7-S10). Nevertheless, as shown in Table 1, various monomer responses were obtained when using PDBA2: fructose and mannose induced enhanced signals while xylose and galactose induced opposite characters, and almost no responses were observed when added glucose or ribose. Structurally, two pairs of cis-1,2- or 1,3-diols were found in the five-membered furanose form of glucose, xylose, galactose and mannose, thus each molecule of them was capable of binding with two molecules of dibronic acids simultaneously. The shortened spatial distance facilitated π-π interaction between pyrene moieties of different diboronic acid receptors, followed by generating excimer emission (Figure 3, S8-S10, S12, S14-S16). Although the abundance of reactive furanose is much lower than that of corresponding pyranose61-62, its “local” association constants63 which just aim at the binding between boronic acid with a certain diol moiety functions in an anomer are quite higher because of the low ring strain in boronic esters. When exploiting PDBA1 as receptor, almost no responses were observed upon addition


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of ribose that contains only a pair of cis-diol in either furanose or pyranose forms (Figure S11). However, under

reactive species, from β-D-pyranose form acted as a bidentate ligand to β-D-furanose with only one binding site.64

Table 1. Profiles of fluorescence responses towards six monosaccharides at 100 μM and monotonous response ranges.

Relative Ratio

Considering the structural complexities of host and guest in the Excimer emission[a, b] Monotonous range (μM)[c] Monomer emission[a, b] supramolecular system, some plausible patterns of boronic esPDBA1 PDBA2 PDBA1 PDBA2 PDBA1 PDBA2 ters were put forward to underGlu − N + + 0-500 0-500 stand the binding behaviors (Figure 6). At low concentration of Fru − + + + 0-100 0-100 analytes, 2:1 PDBA : monosacchaXyl − − + + 0-500 0-500 ride boronate was assumed to be Gal − − + + 0-500 0-500 the primary species, in which the π-π interaction between pyrene Man − + + + 0-500 0-100 groups was potentially existed and Rib N N N + 0-500 0-100 resulted in excimer emission. The [a] “−”/“+” means fluorescence intensity decreased or increased upon addition of 100 μM monoremained two boronic acid resisaccharides, respectively; “N” means no obvious variation. [b] Monomer emission of PDBA1 and dues belonged to different recepPDBA2 were all evaluated at 381 nm, excimer emission of PDBA1 and PDBA2 were evaluated at 528 tors can be blocked by another nm and 510 nm, respectively. [c] Both monomer emission and excimer emission changed monotoone or two analyte molecules to nously at the given concentration range. form 2:2 mono-blocking dimer or (a) 2:3 di-blocking dimer. All of the three kinds of boronates Glu Fru assembled to form corresponding multimer adopting Xyl Gal 25 n:(n-1), n:n, n:(n+1) stoichiometric ratio, respectively. For Man Rib the none-blocking and di-blocking multimer, the simplest 20 ratio of PDBA to monosaccharide would approximate to 1:1 if the value of n is great enough. Although the covalent 15 linkages as well as the hydrophobic π-π interaction were considered to be the synergistic driving forces for aggre10 gates formation, what should be realized is that the decreasing entropy would not allow the continuous growth 5 of aggregates, which has been intuitively reflected in the 0 profile of time-dependent particle size (Figure 4). The 0 10 20 30 40 50 macrocyclic 2:2 di-blocking dimer was obtained from the -5 [Monosaccharides] (10 M) mono-blocking counterpart, the rigid arrangement deGlu Fru (b) creased spatial freedom and may conduce to a more effiXyl Gal 3.5 cient excimer emission. In addition, 1:1 mono-blocking or Man Rib di-blocking monomer were also reasonable forms in the 3.0 complex system, and the existence of the latter can be supported by our previous work, in which the structure of 2.5 1:1 NHoBA:glucose macrocyclic boronic ester was confirmed by MALDI-TOF-MS analysis.7c Amount of 1:2 di2.0 blocking monomer would increase dramatically if ana1.5 lytes was seriously excessive. Even though both the dimers and multimers are likely to generate excimer emis1.0 sion, however, the actual weight contributions will be different from each other. Therefore, the elusory conver0.5 0 10 20 30 40 50 sions among various kinds of possible complexes should -5 be related to the non-monotonous variations of fluores[Monosaccharides] (10 M) cence responses in some cases (Table 1). Figure 5. Relative ratios of fluorescence signals towards monosacRelative Ratio

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


charides using PDBA1 (a) or PDBA2 (b) as sensor at pH 10.0. [PDBA1] = [PDBA2] = 100 μM, λex = 327 nm, λem (PDBA1) = 381/528 nm, λem (PDBA2) = 381/510 nm, slitex = slitem = 10 nm.

the same conditions, the binding between ribose and PDBA2 induced obvious excimer emission (Figure S17), which might be related to a certain but unproven reactive site. As for fructose, an inflection point arose at the concentration of about 100 μM in excimer emission (Figure S7, S13), which was caused by the alteration of primary

Understandably, the formation of dimers and multimers, which induced aggregates, was highly dependent on the abundances of effective analytes species and the position/orientation of their cis-diol moieties. Additionally, we speculated that the multiple flexible linkers belonged to diboronic acids also facilitated the optimization of three-dimensional structures of aggregates to minimize energy, which can be perceived as the self-adaptive capac-



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ity of sensors. As a result, from the aspect of fluorescence responses, although the specificity towards a certain


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Figure 6. Hypothetical binding modes between PDBA and monosaccharides.

analyte was not quite remarkable, but perceptible differences still existed on four fluorescence channels when a sensor interacted with different monosaccharides or different sensors interacted with the same monosaccharide. Combination of multiple dependent variables will enable a better identification for the monosaccharides, if a proper mathematical treatment was employed.

Discriminative sensing via LDA As discussed above, pyrene-functionalized diboronic acids PDBA1 and PDBA2 with two emission bands exhibited different signals towards different monosaccharides. Encouraged by the exhilarating results, the four-channel sensor array, which integrated monomer emission and excimer emission together, was utilized to achieve the “fingerprint” identification of six monosaccharides, and both the values and directions of responses were taken into account. (Figure 7). Testing concentration was designated at 100 μM, which was the inflection point of fluorescence signals of fructose, mannose and ribose (Table 1). The relative excimer emission intensity of PDBA2 in the presence of analyte was much lower than that of PDBA1, since a weak excimer emission background of neat diboronic acid was found relative to monomer emission (Figure 2b). Linear discriminant analysis (LDA) was performed to deal with the multidimensional raw data, which enables the minimization of variation within each data group while maximizing the differences between data groups by establishing linear discriminant functions for each class.65 As shown in Figure 8, six monosaccharides at 100 μM were well-clustered and thoroughly separated from each

other in the 3D canonical score plot, the first three principal factors carried about 84.7%, 8.1%, 6.9% of the total v a r i a t i o n , PDBA1-Monomer PDBA1-Excimer

PDBA2-Monomer PDBA2-Excimer

1.2 0.8

0.15

Log(I/I0)

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


0.00 -0.15 -0.30

Glu

Fru

Xyl

Gal

Man

Rib

Figure 7. Fluorescence responses of monosaccharides on four different channels at pH 10.0 using a fluorescence plate reader. [PDBA1] = [PDBA2] = 100 μM, [monosaccharides] = 100 μM, λex = 327 nm, λem (PDBA1) = 381/528 nm, λem (PDBA2) = 381/510 nm, excitation bandwidth = 5 nm. I/I0: relative fluorescence intensity upon addition of monosaccharides.

respectively. The 100% classification accuracy was confirmed by cross-validation based on “leave-one-out” method (LOOCV), indicating the availability of the sensor array in categorizing unknowns. Ideal discriminations were also achieved when adopting four incomplete arrays containing only three emission channels (Figure S18). In addition, conversion of original titration data concerning 20100 μM analytes into canonical scores resulted in satisfactory analytes-separated 2D plot with 83.3% correct classi-



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fication in 30 cases. More interestingly, point groups of different monosaccharides located in different sectors (Figure 9). In the concentration-dependent 3D score plot,

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the connected lines of various monosaccharides stemmed from the analytes-free point and extended in different

Figure 8. Four channels-based 3D canonical score plot of six monosaccharides at 100 μM analyzed by LDA (5 trials each). Cross-validation showed 100% classification accuracy.

cose concentration that is higher than renal threshold always induces glycosuria. Even though some kinds of glucose sensor systems based on enzymatic approaches have been employed to perform clinical tests with high selectivity and sensitivity,68 environmentally insensitive synthetic sensors are still required to broaden service conditions. Except for glucose, some other monosaccharides like fructose and galactose are found in blood with concentration less than 0.1 mM.66 Particularly, as a metabolite of anaerobic biological processes, lactate is also caFigure 9. Four channels-based 2D canonical score plot of six monosaccharides at a concentration range (20, 40, 60, 80, 100 μM) analyzed by LDA. Cross-validation showed 83.3% classification accuracy. pable to interact with boronic acid, and its blood condirections (Figure S19). In the structure matrix, among all centration level will increased up to about 0.5 mM after fluorescence channels, PDBA2-monomer emission was exercise.66,69 In order to evaluate the anti-interference highly correlated with the uppermost factor (Table S1), capacity of current synthesized boronlectins, a series which can be attributed to its polytropic responses tosamples with 5 mM glucose and potential interference wards different monosaccharides. Accordingly, it has species in blood at physiological concentrations were been found that the classification accuracy would deadded into the solution of sensors. To our delight, no obcreased to 70% if a sensor array without PDBA2-monomer vious signal fluctuates were observed (Figure 10), the emission channel was chosen to perform LDA (Figure maximum variations were calculated to be only 15% and S20). 7% respectively in PDBA1- and PDBA2-involved systems. Practical applications in glucose sensing Actually, the positive effect resulted from interferencesinduced assembly, to some extent, offset the negative Glucose is the predominant monosaccharides in human effect brought by the competition of binding sites. Addiblood, and its normal range of concentration is found to 66 tionally, relative fluorescence ratios were correlated linebe 4-8 mM for healthy individuals. Insufficient regulaarly with urinary glucose concentrations (Figure 11). tion of blood glucose level results in diabetes and a series Therefore, diboronic acids PDBA1 and PDBA2 are promisof complications such as blindness, heart disease and ing in detecting glucose of practical samples. It is note7,67 Alzheimer’s disease. Furthermore, abnormal blood glu-


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worthy that signal amplification occurred when using PDBA1 in contrast with the cases of PDBA2 which exhibited higher excimer emission background than the former.

Figure 10. Relative ratios of PDBA1 and PDBA2 towards simulative blood samples (containing glucose (5 mM) and various potential interferences like monosaccharides (0.1 mM) or lactate (0.5 mM)). Practical samples were diluted 10 times by pH 10.0 buffer solution before testing.

PDBA1 PDBA2

5

Relative ratio

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


2

4

R = 0.9955

3 2 2

R = 0.9977

1 0

20

40

60

80

100

[Diluted Urinary Glu] (µM) Figure 11. Linear relationships between relative ratios and urinary glucose concentrations using PDBA1 or PDBA2 as sensor. Simulative urine samples (containing glucose at mM level) were diluted 100 times by pH 10.0 buffer solution before testing.

CONCLUSION Pyrene-functionalized water-soluble diboronic acids with flexible linkers were designed and expediently synthesized to achieve both monomer and excimer fluorescence responses towards various monosaccharides at μM level. The pH values and aging time have been proved to be paramount important in the signal outputs of the analytes-induced assembly systems. The integrated sensor array with four fluorescence channels was capable to ideally discriminate six monosaccharides at a certain concentration or a given concentration range via LDA with excellent accuracy, and PDBA2-monomer emission occupied the greatest discriminatory contribution among

all channels if taking concentration factor into account. To the best of our knowledge, it is an ingenious work to employ polytropic fluorescence responses of different emission bands of pyrene fluorophore to distinguish monosaccharides with highly similar chemical structures. Moreover, the flexible structures of sensors were highlighted since the self-adaptive capacity could efficiently modulate the conformations of aggregates involved various monosaccharides. From a practical perspective, it was reliable to sense glucose in blood or urine using PDBA1 or PDBA2, even though some potential interferences existed. Encouraged by the current work, explorations of some other novel and elegant molecules with high spatial freedom are in progress to pursue a broader saccharide identification spectrum.

EXPERIMENTAL SECTION General All chemicals were purchased as reagent grade and used without further purification. Reactions were monitored by analytical thin-layer chromatography (TLC) on silica gel F254 glass plates and visualized under UV light (254nm). Flash column chromatography was performed on silica gel (200-300 mesh). Reversed-phase column chromatography was performed using SiliaSphere C18 as packing. 1H NMR and 13C NMR spectra were recorded with a Bruker Avance III 400 MHz NMR spectrometer, and the chemical shifts (in ppm) were referenced to solvent peaks. Coupling constants in Hz were calculated from the one-dimensional spectra. High resolution electrospray ionization mass spectra (HRMSESI) were recorded with Waters LCT Premier XEmass spectrometer. Both the buffer solutions and analytes stock solutions were prepared with distilled H2O purified by a quartz subboiling distiller. UV-Vis spectra were recorded on a Shimadzu UV-2600 spectrophotometer. Fluorescence emission spectra were recorded with a Varian Cary Eclipse spectrophotometer. All of the routine spectra were measured in a quartz cell with 1 cm path length. Fluorescence responses upon addition of certain concentration of analytes that were used for LDA analysis (performed by SPSS v20.0) were obtained on a microplate reader (Thermo Scientific, Varioskan Flash) using 96-well plates (Thermo Scientific, lighttight, flat bottom, nonsterile). Particle size data were obtained through dynamic laser scattering (ZetaPLUS, Brookhaven Instruments Corporation). Synthesis N, N-bis(pyridin-2-ylmethyl)-4-pyrenylbutanamide (PD1): 1-pyrenebutyric acid (300 mg, 1.040 mmol) and N, N-di-2-picolylamine (DPA, 207.3 mg, 1.040 mmol, 1.0 equiv.) were dissolved in 10 mL anhydrous DMF, and then O-(benzotriazol-1-yl)-N, N, N', N'tetramethyluronium hexafluorophosphate (HBTU, 394.6 mg, 1.040 mmol, 1.0 equiv.) and N, Ndiisopropylethylamine (DIEA, 180 μL, 1.0 equiv.) were



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added into the solution. The starting materials were completely consumed as detected by TLC (DCM/MeOH =15/1) after stirring for 24 h at room temperature. Then DMF was evaporated under vacuum and the residue was diluted with DCM (150 mL), washed with saturated NaHCO3 solution (3×10 mL) and brine (3×10 mL), and dried with MgSO4. After removal of the solvent, the residue was purified by column chromatography (DCM/MeOH =80/1) to give compound PD1 as a flaxen spumescent solid (413.7 mg, 85%). 1H NMR (400 MHz, CDCl3): δ = 2.22-2.29 (m, 2H), 2.55 (t, J = 7.1 Hz, 2H), 3.40 (t, J = 7.4 Hz, 2H), 4.64 (s, 2H), 4.82 (s, 2H), 6.97-7.01 (m, 2H), 7.15-7.18 (dd, J = 6.8, 5.3 Hz, 1H), 7.35 (d, J = 7.8 Hz, 1H), 7.40 (td, J = 7.7, 1.6 Hz, 1H), 7.63 (td, J = 7.7, 1.5 Hz, 1H), 7.82 (d, J = 7.8 Hz, 1H), 7.96-8.01 (m, 3H), 8.04 (s, 1H), 8.07 (d, J = 2.8 Hz, 1H), 8.15 (d, J = 7.6 Hz, 2H), 8.31 (d, J = 9.2 Hz, 1H), 8.42 (d, J = 4.3 Hz, 1H), 8.50 (d, J = 4.4 Hz, 1H) ppm; 13C NMR (100 MHz, CDCl3): δ = 27.0, 32.4, 32.7, 51.5, 53.1, 120.5, 122.27, 122.30, 122.5, 123.6, 124.7, 124.76, 124.80, 124.99, 125.03, 125.8, 126.6, 127.3, 127.4, 127.5, 128.8, 129.8, 130.9, 131.4, 136.2, 136.6, 136.8, 149.1, 149.7, 156.6, 157.5, 173.6 ppm. HRMS (ESI): m/z calcd for C32H28N3O ([M+H]+): 470.2232; found: 470.2235.

(bromomethyl)phenylboronic acid (220.6 mg, 1.027 mmol, 3.0 equiv.) were dissolved in 5 mL THF, then the mixture was refluxed at 65 °C for 48 h and a flaxen solid was obtained. TLC (DCM/MeOH =15/1) demonstrated that there were still some starting materials remained. After cooling to room temperature, the supernatant was removed, and the residual solid was washed by THF, followed by purification through reversed-phase column chromatography (SiliaSphere C18) eluting with a MeOH/H2O (6:4) mixed solvent. MeOH and H2O in eluate were respectively removed via rotary evaporation and lyophilization to afford PDBA2 as a flaxen flocculent solid (100.0 mg, 33%). 1H NMR (400 MHz, DMSO-d6): δ = 1.40-1.55 (m, 2H), 1.57-1.68 (m, 2H), 2.51-2.61 (m, 2H), 3.173.24 (m, 2H), 4.15 (s, 4H), 6.06 (s, 4H), 6.65 (d, J = 7.7 Hz, 2H), 7.26-7.42 (m, 5H), 7.79-7.92 (m, 3H), 7.95-8.15 (m, 7H), 8.15-8.29 (m, 8H), 8.54 (t, J = 7.6 Hz, 2H), 8.77 (d, J = 6.0 Hz, 2H) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 26.1, 29.4, 32.9, 55.0, 55.2, 57.9, 60.5, 74.6, 123.8, 124.6, 124.7, 125.3, 125.38, 125.44, 126.6, 127.0, 127.5, 127.7, 127.8, 127.87, 127.9, 128.42, 128.43, 128.5, 129.7, 130.8, 131.1, 131.3, 136.2, 137.0, 137.6, 146.4, 146.7, 155.6 ppm. HRMS (ESI): m/z calcd for C46H45B2BrN3O4 ([M-Br]+): 804.2774; found: 804.2779.

N, N-bis[(2-boronic acid)benzyl pyridinium-2ylmethyl]-4-pyrenylbutanamide dibromide (PDBA1): Compound PD1 (219.6 mg, 0.468 mmol) and 2(bromomethyl)phenylboronic acid (301.4 mg, 1.403 mmol, 3.0 equiv.) were dissolved in 7.5 mL THF, then the mixture was refluxed at 65 °C for 48 h and a flaxen solid was obtained. TLC (DCM/MeOH =15/1) demonstrated that there were still some starting materials remained. After cooling to room temperature, the supernatant was removed, and the residual solid was washed by THF, followed by purification through reversed-phase column chromatography (SiliaSphere C18) eluting with a MeOH/H2O (6:4) mixed solvent. MeOH and H2O in eluate were respectively removed via rotary evaporation and lyophilization to afford PDBA1 as a flaxen flocculent solid (169.8 mg, 40%). 1H NMR (400 MHz, DMSO-d6): δ = 1.93-2.00 (m, 2H), 2.37 (t, J = 5.6 Hz, 2H), 3.22-3.29 (m, 2H), 5.11 (s, 2H), 5.24 (s, 2H), 6.05 (s, 2H), 6.10 (s, 2H), 6.82-6.88 (m, 2H), 7.40-7.48 (m, 4H), 7.85 (d, J = 7.8 Hz, 2H), 7.91 (d, J = 6.6 Hz, 1H), 8.04-8.15 (m, 7H), 8.17-8.22 (m, 2H), 8.29 (t, J = 6.7 Hz, 2H), 8.34 (d, J = 9.3 Hz, 1H), 8.40 (s, 2H), 8.47 (s, 2H), 8.62 (t, J = 7.9 Hz, 2H), 8.81-8.89 (m, 2H) ppm; 13C NMR (100 MHz, DMSO-d6): δ = 26.7, 31.3, 32.4, 47.6, 49.5, 60.7, 123.9, 124.6, 124.7, 125.3, 125.4, 125.5, 125.8, 126.6, 126.7, 127.0, 127.1, 127.2, 127.7, 127.8, 127.9, 128.4, 128.5, 128.6, 128.8, 129.8, 130.8, 131.1, 131.2, 131.3, 136.1, 136.4, 136.7, 136.8, 137.2, 146.5, 146.6, 146.8, 147.1, 153.8, 154.3, 174.3 ppm. HRMS (ESI): m/z calcd for C46H43B2BrN3O5 ([M-Br]+): 818.2567; found: 818.2584.

Preparation of Samples

N, N-bis[(2-boronic acid)benzyl pyridinium-2ylmethyl]-N-(4-pyrenylbutyl)amine dibromide (PDBA2): 1-(4-bromobutyl)pyrene and PD2 were synthesized as previous literatures reported.41-42 Compound PD2 (155.9 mg, 0.342 mmol) and 2-

Buffer solutions used in pH profile were list as below: pH 3.0: Glycine-HCl, 50 mM; pH 4.0-5.0: NaOAcAcOH, 50mM; pH 6.0-8.0: KH2PO4-NaOH, 50 mM; pH 9.0: GlycineNaOH, 50 mM; pH 10.0-11.0: NaHCO3-NaOH, 50 mM. Titration experiments: Stock solution of PDBA1 or PDBA2 (10 mM in DMSO) was added into 3 mL carbonate buffer (pH 10.0, 50 mM), final concentration of sensor was 100 μM. Then certain amount of stock solution of monosaccharide (0.01 M or 0.1 M in H2O) was added into the sensing system. Control group was set to be sensor only. Fluorescence emission spectra, UV-Vis absorption spectra and effective diameters of particles were measured after aging for 3 h. Buffer solution used in DLS analysis was preprocessed by 220 nm filtration membrane. Fluorescence responses of monosaccharides at 100 μM for LDA: Stock solution of PDBA1 or PDBA2 (10 mM in DMSO) was diluted to 100 μM using carbonate buffer (pH 10.0, 50 mM) and mixed with the stock solution of monosaccharides (5 mM in H2O). The total volume in each well of 96-well plate was about 200 μL. Final concentrations of analytes were 100 μM. Control groups contained no analytes, and blank groups contained buffer solution only. Data were collected on a fluorescence plate reader after aging for 3 h. Glucose sensing with interferences existed in blood: Stock solutions of glucose (0.5 M in H2O) and an interference species (0.5 M for lactate in H2O, 0.01 M for monosaccharides in H2O) were added into 3 mL


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phosphate buffer (pH 7.4, 50 mM), final concentrations of glucose, lactate and monosaccharide interferences in the simulative blood samples were 5 mM, 0.5 mM and 0.1 mM, respectively. Then 0.3 mL prepared samples were mixed with 2.7 mL carbonate buffer (pH 10.0, 50 mM) containing PDBA1 or PDBA2, and the final concentrations of sensor, glucose, lactate and monosaccharide interferences in testing samples were 100 μM, 500 μM, 50 μM and 10 μM, respectively. Control group contained no interferences while blank group contained sensor only in identical mixed buffer solution. Fluorescence emission spectra were measured after aging for 3 h. Glucose sensing in simulative urine: Artificial urine without glucose was prepared as previous literature reported.70 Simulative morbid urine samples were obtained via adding stock solution of glucose (0.5 M in H2O), final concentrations of glucose were 1-10 mM. Then the prepared samples were diluted by carbonate buffer (pH 10.0, 50 mM) containing PDBA1 or PDBA2, and the final concentrations of sensor and glucose were 100 μM and 10-100 μM, respectively. Control group was set to be sensor only. Fluorescence emission spectra were measured after aging for 3 h. Calculation of constants Aggregating constant of PD1 was calculated by fitting the molar absorption coefficients with the function as below:45-46

ε=

2K agg c + 1 − 4K agg c + 1 2

2K agg c 2

(ε f − ε a ) + ε a

ɛ: apparent molar extinction coefficient at 343 nm; Kagg: equilibrium constant of the entire aggregation process, assuming every step of aggregation share a same equilibrium constant; c: total concentration of PD1; ɛf : molar extinction coefficient of free species of PD1; ɛa : molar extinction coefficient of aggregated species of PD1. The change of Gibbs free energy was calculated via the equation: ΔGagg = -RTlnKagg.

ASSOCIATED CONTENT Supporting Information. UV-Vis absorption spectra of PD and PDBA at different concentrations, fluorescence spectra of PDBA at different pH values, linear relation between fluorescence ratios and glucose concentrations, time-dependent spectra of PDBA1 upon addition of glucose, particle size distribution of aggregates consisted of PDBA1 and glucose, fluorescence spectra of PDBA upon addition of monosaccharides, canonical score plots of monosaccharides analyzed by LDA, correlation matrix between principal factors and fluorescence channels, 1H and 13C NMR spectra of PD and PDBA. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Author

* [email protected]

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT The project was financially supported by the National Natural Science Foundation of China (21272027).

REFERENCES (1) Stick, R. V.; Williams, S. Carbohydrate: The Essential Molecules of Life; Elsevier, 2010. (2) Karp, G. Cell and Molecular Biology: Concepts and Experiments; John Wiley & Sons, 2008. (3) Ouerfelli, O.; Warren, J. D.; Wilson, R. M.; Danishefsky, S. J. Synthetic Carbohydrate-based Antitumor Vaccines: Challenges and Opportunities. Expert Rev. Vaccines 2005, 4, 677-685. (4) Danishefsky, S. J.; Allen, J. R. From the Laboratory to the Clinic: a Retrospective on Fully Synthetic Carbohydrate-based Anticancer Vaccines. Angew. Chem. Int. Ed. 2000, 39, 836-863. (5) Wu, X.; Li, Z.; Chen, X. X.; Fossey, J. S.; James, T. D.; Jiang, Y. B. Selective Sensing of Saccharides Using Simple Boronic Acids and Their aggregates. Chem. Soc. Rev. 2013, 42, 8032-8048. (6) Bull, S. D.; Davidson, M. G.; van den Elsen, J. M. H.; Fossey, J. S.; Jenkins, A. T.; Jiang, Y. B.; Kubo, Y.; Marken, F.; Sakurai, K.; Zhao, J.; James, T. D. Exploiting the Reversible Covalent Bonding of Boronic Acids: Recognition, Sensing, and Assembly. Acc. Chem. Res. 2013, 46, 312-326. (7) Sun, X.; James, T. D. Glucose Sensing in Supramolecular Chemistry. Chem. Rev. 2015, 115, 8001-8037. (8) Zhai, W.; Sun, X.; James, T. D.; Fossey, J. S. Recent Progress in Boronic Acid-based Carbohydrate Sensing. Chem. Asian J. 2015, 10, 1836-1848. (9) Davis, A. P.; Wareham, R. S. A Tricyclic Polyamide Receptor for Carbohydrates in Organic Media. Angew. Chem. Int. Ed. 1998, 37, 2270-2273. (10) Lecollinet, G.; Dominey, A. P.; Velasco, T.; Davis, A. P. Highly Selective Disaccharide Recognition by a Tricyclic Octaamide Cage. Angew. Chem. Int. Ed. 2002, 41, 4093-4096. (11) Ferrand, Y.; Crump, M. P.; Davis, A. P. A Synthetic Lectin Analog for Biomimetic Disaccharide Recognition. Science 2007, 318, 619-622. (12) Barwell, N. P.; Crump, M. P.; Davis, A. P. A Synthetic Lectin for β-Glucosyl. Angew. Chem. Int. Ed. 2009, 48, 7673-7676. (13) Ke, C.; Destecroix, H.; Crump, M. P.; Davis, A. P. A Simple and Accessible Synthetic Lectin for Glucose Recognition and Sensing. Nat. Chem. 2012, 4, 718-723. (14) Hall, D. G. Boronic Acids: Preparation, Applications in Organic Synthesis and Medicine; John, 2006. (15) Lorand, J. P.; Edwards, J. O. Polyol Complexes and Structure of the Benzeneboronate Ion. J. Org. Chem. 1959, 24, 769-774. (16) Ni, N.; Laughlin, S.; Wang, Y.; Feng, Y.; Zheng, Y.; Wang, B. Probing the General Time Scale Question of Boronic Acid Binding with Sugars in Aqueous Solution at Physiological pH. Bioorg. Med. Chem. 2012, 20, 2957-2961. (17) Nishiyabu, R.; Kubo, Y.; James, T. D.; Fossey, J. S. Boronic Acid Building Blocks: Tools for Sensing and Separation. Chem. Commun. 2011, 47, 1106-1123. (18) James, T. D.; Sandanayake, K. R. A. S.; Shinkai, S. A Glucoseselective Molecular Fluorescence Sensor. Angew. Chem. Int. Ed. 1994, 33, 2207-2209. (19) Yang, W.; He, H.; Drueckhammer, D. G. Computer-guided Design in Molecular Recognition: Design and Synthesis of a Glucopyranose Receptor. Angew. Chem. Int. Ed. 2001, 40, 1714-1718.



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

(20) Arimori, S.; Bell, M. L.; Oh, C. S.; Frimat, K. A.; James, T. D. Modular Fluorescence Sensor for Saccharides. J. Chem. Soc., Perkin Trans. 1 2002, 803-808. (21) Gamsey, S.; Miller, A.; Olmstead, M. M.; Beavers, C. M.; Hirayama, L. C.; Pradhan, S.; Wessling, R. A.; Singaram, B. Boronic Acid-based Bipyridinium Salts as Tunable Receptors for Monosccharides and α-Hydroxycarboxylates. J. Am. Chem. Soc. 2007, 129, 1278-1286. (22) Schiller, A.; Vilozny, B.; Wessling, R. A.; Singaram, B. Going Beyond Continuous Glucose Monitoring with Boronic Acid Appended Bipyridinium Salts. In Reviews in Fluorescence 2009, (Ed.: Geddes, C.); Springer: New York, 2011, pp. 155-191. (23) Schiller, A., Wessling, R. A.; Singaram, B. A Fluorescent Sensor Array for Saccharides Based on Boronic Acid Appended Bipyridinium Salts. Angew. Chem. Int. Ed. 2007, 46, 6457-6459. (24) Zhang, X.-T.; Wang, S.; Xing, G.-W. Novel Boronlectins Based on Bispyridium Salt with a Flexible Linker: Discriminative Sensing of Lactose and Other Monosaccharides and Disaccharides in Aqueous Solution. Chem. Asian. J. 2015, 10, 2594-2598. (25) Springsteen, G.; Wang, B. Alizarin Red S. as a General Optical Receptor for Studying the Binding of Boronic Acids with Carbohydrates. Chem. Commun. 2001, 1608-1609. (26) Kanekiyo,Y.; Naganawa,R.; Tao, H. Fluorescence Detection of ATP Based on the ATP-mediated Aggregation of Pyreneappended Boronic Acid on a Polycation. Chem. Commun. 2004, 1006-1007. (27) Yu, C.; Yam, V. W.-W. Glucose Sensing via Polyanion Formation and Induced Pyrene Excimer Emission. Chem. Commun. 2009, 1347-1349. (28) Phillips, M. D.; Fyles, T. M.; Barwell, N. P.; James,T. D. Carbohydrate Sensing Using a Fluorescent Molecular Tweezer. Chem. Commun. 2009, 6557-6559. (29) Huang, Y.-J.; Ouyang, W.-J.; Wu, X.; Li, Z.; Fossey, J. S.; James, T. D.; Jiang, Y.-B. Glucose Sensing via Aggregation and the Use of “Knock-Out” Binding to Improve Selectivity. J. Am. Chem. Soc. 2013, 135, 1700-1703. (30) Neupane, L. N.; Han, S. Y.; Lee, K.-H. Ratiometric Fluorescence Sensing of Sugars via a Reversible Disassembly and Assembly of the Peptide Aggregates Mediated by Sugars. Chem. Commun. 2014, 50, 5854-5857. (31) Liu, Y.; Deng, C.; Tang, L.; Qin, A.; Hu, R.; Sun, J. Z.; Tang, B. Z. Specific Detection of D-Glucose by a Tetraphenylethenebased Fluorescent Sensor. J. Am. Chem. Soc. 2011, 133, 660-663. (32) Tong, A.-J.; Yamauchi, A.; Hayashita, T.; Zhang, Z.-Y.; Smith, B. D.; Teramae, N. Boronic Acid Fluorophore/β-Cyclodextrin Complex Sensors for Selective Sugar Recognition in Water. Anal. Chem. 2001, 73, 1530-1536. (33) Shimpuku, C.; Ozawa, R.; Sasaki, A.; Sato, F.; Hashimoto, T.; Yamauchi, A.; Suzuki, I.; Hayashita, T. Selective Glucose Recognition by Boronic Acid Azoprobe/γ-Cyclodextrin Complexes in Water. Chem. Commun. 2009, 1709-1711. (34) Wu, X.; Lin, L.-R.; Huang, Y.-J.; Li, Z.; Jiang, Y.-B. A 2:2 Stilbeneboronic Acid-γ-Cyclodextrin Fluorescent Ensemble Highly Selective For Glucose in Aqueous Solutions. Chem. Commun. 2012, 48, 4362-4364. (35) Xu, Z.; Uddin, K. M. A.; Kamra, T.; Schnadt, J.; Ye, L. Fluorescent Boronic Acid Polymer Grafted on Silica Particles for Affinity Separation of Saccharides. ACS Appl. Mater. Interfaces 2014, 6, 1406-1414. (36) Vilozny, B.; Schiller, A.; Wessling, R. A.; Singaram, B. Multiwell Plates Loaded with Fluorescent Hydrogel Sensors for Measuring pH and Glucose Concentration. J. Mater. Chem. 2011, 21, 7589-7595.

Page 12 of 14

(37) Sun, X.; Zhu, B.; Ji, D.-K.; Chen, Q.; He, X.-P.; Chen, G.-R.; James, T. D. Selective Fluorescence Detection of Monosaccharides Using a Material Composite Formed Between Grapheme Oxide and Boronate-based Receptors. ACS Appl. Mater. Interfaces 2014, 6, 10078-10082. (38) Arimori, S.; Bell, M. L.; Oh, C. S.; Frimat, K. A.; James, T. D. Modular Fluorescence Sensors for Saccharides. Chem. Commun. 2001, 1836-1837. (39) Xing, Z.; Wang, H.-C.; Cheng, Y.; Zhu, C.; James, T. D.; Zhao, J. Selective Saccharide Recognition Using Modular Diboronic Acid Fluorescent Sensors. Eur. J. Org. Chem. 2012, 12231229. (40) Neupane, L. N.; Lohani, C. R.; Kim, J.; Lee, K.-H. A Dual Role of Phenylboronic Acid as a Receptor for Carbohydrates as well as a Quencher for Neighboring Pyrene Fluorophore. Tetrahedron 2013, 69, 11057-11063. (41) Lampkins, A. J.; O’Neil, E. J.; Smith, B. D. Bio-orthogonal Phosphatidylserine Conjugates for Delivery and Imaging Applications. J. Org. Chem. 2008, 73, 6053-6058. (42) Cho, H. K.; Lee, D. H.; Gong, J.-I. A Fluorescent Pyrophosphate Sensor via Excimer Formation in Water. Chem. Commun. 2005, 1690-1692. (43) Bittermann, H.; Siegemund, D.; Malinovskii, V. L.; Häner, R. Dialkynylpyrenes: Strongly Fluorescent, Environment-sensitive DNA Building Blocks. J. Am. Chem. Soc. 2008, 130, 15285-15287. (44) Vybornyi, M.; Rudnev, A. V.; Langenegger, S. M.; Wandlowski, T.; Calzaferri, G.; Häner, R. Formation of Twodimensional Supramolecular Polymers by Amphiphilic Pyrene Oligomers. Angew. Chem. Int. Ed. 2013, 52, 11488-11493. (45) Martin, R. B. Comparisons of Indefinite Self-association Models. Chem. Rev. 1996, 96, 3043-3064. (46) Würthner, F.; Thalacker, C.; Diele, S.; Tschierske, C. Fluorescent J-type Aggregates and Thermotropic Columnar Mesophases of Perylene Bisimide Dyes. Chem. Eur. J. 2001, 7, 2245-2253. (47) Ferrier, R. J. Carbohydrate Boronates. Adv. Carbohydr. Chem. Biochem. 1978, 35, 31-80. (48) Bosch, L. I.; Fyles, T. M.; James, T. D. Binary and Ternary Phenylboronic Acid Complexes with Saccharides and Lewis Bases. Tetrahedron 2004, 60, 11175-11190. (49) Zheng, Y.; Long, H.; Schatz, G. C.; Lewis, F. D. Duplex and Hairpin Dimer Structures for Perylene Diimide-oligonucleotide Conjugates. Chem. Commun. 2005, 4795-4797. (50) Wang, W.; Li, L.-S.; Helms, G.; Zhou, H.-H.; Li, A. D. Q. To Fold or to Assemble? J. Am. Chem. Soc. 2003, 125, 1120-1121. (51) Clark, A. E.; Qin, C.; Li, A. D. Q. Beyond Exciton Theory: a Time-dependent DFT and Franck-Condon Study of PeryleneDiimide and Its Chromophoric Dimer. J. Am. Chem. Soc. 2007, 129, 7586-7595. (52) Cooper, C. R.; James, T. D. Synthesis and Evaluation of DGlucosamine-selective Fluorescent Sensors. J. Chem. Soc., Perkin Trans. 1 2000, 963-969. (53) DiCesare, N.; Lakowicz, J. R. A New Highly Fluorescent Probe for Monosaccharides Based on a Donor-acceptor Diphenyloxazole. Chem. Commun. 2001, 2022-2023. (54) Cao, H.; Diaz, D. I.; DiCesare, N.; Lakowicz, J. R.; Heagy, M. D. Monoboronic Acid Sensor that Displays Anomalous Fluorescence Sensitivity to Glucose. Org. Lett. 2002, 4, 1503-1505. (55) Arimori, S.; Bell, M. L.; Oh, C. S.; James, T. D. A Modular Fluorescence Intramolecular Energy Transfer Saccharide Sensor. Org. Lett. 2002, 4, 4249-4251. (56) Cordes, D. B.; Gamsey, S.; Singaram, B. Fluorescent Quantum Dots with Boronic Acid Substituted Viologens to Sense Glu-


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cose in Aqueous Solution. Angew. Chem. Int. Ed. 2006, 45, 38293832. (57) Zhang, Y.; Gao, X.; Hardcastle, K.; Wang, B. Water-soluble Fluorescent Boronic Acid Compounds for Saccharide Sensing: Substituted Effects on Their Fluorescence Properties. Chem. Eur. J. 2006, 12, 1377-1384. (58) Jin, S.; Wang, J.; Li, M.; Wang, B. Synthesis, Evaluation, and Computational Studies of Naphthalimide-based Longwavelength Fluorescent Boronic Acid Receptor. Chem. Eur. J. 2008, 14, 2795-2804. (59) Zhai, J.; Pan, T.; Zhu, J.; Xu, Y.; Chen, J.; Xie, Y.; Qin, Y. Boronic Acid Functionalized Boron Dipyrromethene Fluorescent Probes: Preparation, Characterization, and Saccharides Sensing Applications. Anal. Chem. 2012, 84, 10214-10220. (60) Lopez, C. S.; Huvelle, M. A. L.; Uhrig, M. L.; Leskow, F. C.; Spagnuolo, C. C. Recognition of Saccharides in the NIR Region with a Novel Fluorogenic Boronolectin: In Vitro and Live Cell Labeling. Chem. Commun. 2015, 51, 4895-4898. (61) Angyal, S. J. The Composition of Reducing Sugars in Solution. Adv. Carbohydr. Chem. Biochem. 1984, 42, 15-68; (62) Angyal, S. J. The Composition of Reducing Sugars in Solution: Current Aspects. Adv. Carbohydr. Chem. Biochem. 1991, 49, 19-35. (63) van den Berg, R.; Peters, J. A.; van Bekkum, H. The Structure and (Local) Stability Constants of Borate Esters of Mono- and Di-saccharides as Studied by 11B and 13C NMR Spectroscopy. Carbohydr. Res. 1994, 253, 1-12. (64) Norrild, J. C.; Eggert, H. Boronic Acids as Fructose Sensors. Structure Determination of the Complexes Involved Using 1JCC Coupling Constants. J. Chem. Soc., Perkin Trans. 2 1996, 25832588. (65) Hughes, A. D.; Glenn, I. C.; Patrick, A. D.; Ellington, A.; Anslyn, E. V. A Pattern Recognition Based Fluorescence Quenching Assay for the Detection and Identification of Nitrated Explosive Analytes. Chem. Eur. J. 2008, 14, 1822-1827. (66) Horgan, A. M.; Marshall, A. J.; Kew, S. J.; Dean, K. E. S.; Creasey, C. D.; Kabilan, S. Crosslinking of Phenylboronic Acid Receptors as a Means of Glucose Selective Holographic Detection. Biosens. Bioelectron. 2006, 21, 1838-1845. (67) de la Monte, S. M.; Wands, J. R. Alzheimer’s Disease is Type 3 Diabetes—Evidence Reviewed. J. Diabetes Sci. Technol. 2008, 2, 1101-1113. (68) Steiner, M.-S.; Duerkop, A.; Wolfbeis, O. S. Optical Methods for Sensing Glucose. Chem. Soc. Rev. 2011, 40, 4805-4839. (69) Friedman, S.; Pace, B.; Pizer, R. Complexation of Phenylboronic Acid with Lactic acid. Stability Constant and Reaction Kinetics. J. Am. Chem. Soc. 1974, 96, 5381-5384. (70) Martinez, A. W.; Phillips, S. T.; Whitesides, G. M. Threedimensional Microfluidic Devices Fabricated in Layered Paper and Tape. Proc. Natl. Acad. Sci. U.S.A. 2008, 105, 19606-19611.



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Aggregates-Based Boronlectins with Pyrene as Fluorophore

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