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Supporting Information

Voltage/pH Driven Mechanized Silica Nanoparticles for

the Multimodal Controlled Release of Drugs

Ting Wang,† GuangPing Sun,† MingDong Wang,† BaoJing Zhou‡ and JiaJun Fu*,† *Corresponding Author, E-Mail: fujiajun668@gmail.com †

School of Chemical Engineering, Nanjing University of Science and Technology,

Nanjing 210094, P. R. China ‡

Institute of Computation in Molecular and Materials Science and Department of

Chemistry, Nanjing University of Science and Technology, Nanjing 210094, P. R.

China

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1. Materials

Hexadecyltrimethylammonium bromide (CTAB, ≥98.0%), tetraethylorthosilicate

(TEOS, ≥99.0%), β-Cyclodextrin (β-CD, ≥97%), lithium hydride (powder, 95%),

propargyl bromide (80% in toluene), lithium iodide (anhydrous, 99.9%),

ferrocenemethanol (97%), sodium azide (≥99%), triethyl phosphite (99.8%), sodium

methoxide (≥97%), propargyl alcohol (99%), 3-(triethoxysilyl)propyl isocyanate

(ICPTES, 95%), p-toluenesulfonyl chloride (≥98%), 2-bromoethanol (95%),

2,2-dimethoxypropane (98%), p-toluenesulfonic acid monohydrate (≥98.5%),

tetrabutylammonium bromide (TBAB, ≥98.0%), bis(cyclopentadienyl)cobalt(III)

hexafluorophosphate (Cob+, 98%), gemcitabine hydrochloride (GEM), and

doxorubicin hydrochloride (DOX, ≥98.0%) were purchased from Sigma-Aldrich.

Copper iodide (≥99.5%), triphenylphosphine (≥99.5) and MTT (3-(4,

5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide, 98%) were obtained from

Aladdin Industrial Inc. (Shanghai, China).

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2. Preparation and Synthesis

2.1 Synthetic Procedure of PTPC

Scheme S1 Synthesis of PTPC.

2.2 Synthetic Procedure of ABP

Scheme S2 Synthesis of ABP.

2.3 Synthetic Procedure of NH2-Fc-β-CD

Scheme S3 Synthesis of NH2-Fc-β-CD.

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2.4 Preparation of MSNPs 1

Scheme S4 Synthetic procedure for preparing MSNPs 1.

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3. Analytical Data

3.1 Characterization of MSNs

Figure S1. (A) SA-XRD pattern and (B) N2 adsorption-desorption isotherm and pore size

distribution of MSNs.

Table S1. Physicochemical properties of the MSNs.

Materials Specific surface area

(m2 g

-1)

Average pore size

(nm)

Pore volume

(cm3 g

-1)

MSNs 1262.57 2.35 0.97

As seen in Figure S1A, the three well-defined diffraction peaks at 2.39°, 4.05° and

4.65°, which corresponded to (100), (110) and (200) reflections, respectively,

suggested the hexagonal mesostructure of the prepared MSNs. N2

adsorption-desorption isotherm of MSNs (Figure S1B) showed the characteristic type-

Ⅳ isotherm, and the specific surface area, average pore diameter, as well as total

pore volume are summarized in Table S1.

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3.2 N2 Adsorption-Desorption Isotherms and SA-XRD Analysis

Figure S2. (A) N2 adsorption-desorption isotherms and (B) pore size distributions of MSNs,

MSNs-PTPC, MSNs-ABP, and MSNPs 1.

Table S2. Physicochemical properties of the MSNs, MSNs-PTPC, MSNs-ABP, and MSNPs 1.

Materials Specific surface area

(m2 g

-1)

Average pore size

(nm)

Pore volume

(cm3 g

-1)

MSNs 1262.57 2.35 0.97

MSNs-PTPC 954.04 2.27 0.86

MSNs-ABP 739.78 2.14 0.67

MSNPs 1 172.86 ------ 0.15

Figure S3. SA-XRD patterns of MSNs, MSNs-PTPC, MSNs-ABP, and MSNPs 1.

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3.3 TG Analysis

Figure S4. TGA analysis of (a) MSNs, (b) MSNs-PTPC, (c) MSNs-ABP, and (d) MSNPs 1.

3.4 2D ROESY NMR Spectra

Figure S5. Partial 2D ROESY spectra (300 MHz, 25℃, D2O) of Fc+-β-CD (0.1 mM) reduced by

-1.5 V voltage.

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3.5 1H NMR Spectra

Figure S6. Partial 1H NMR spectra (300 MHz, 25℃, D2O) (A) Fc-β-CD (0.1 mM); (B) adding 1.0

equiv. (NH4)4Ce(SO4)4·4H2O; (C) adding 1.0 equiv. Vitamin C.

Figure S6 demonstrates the cyclic conversion from Fc-β-CD to Fc+-β-CD by

chemical redox agents. (NH4)4Ce(SO4)4·4H2O and vitamin C were used as the

oxidizing and reducing reagents, respectively. In comparison, upon addition of 1.0

equiv. (NH4)4Ce(SO4)4·4H2O, the peaks assigned to cyclopentadiene groups

disappeared due to the paramagnetic nature of ferrocenium (Fc+). After reduction by

adding Vitamin C, the peaks for ferrocene (Fc) emerged again, indicating the potential

of Fc-β-CD for reversible supramolecular nanovalves.

3.6 UV-Vis Analysis

Figure S7. The UV-Vis spectra of (a) Fc-β-CD (0.1 mM) in aqueous solution; (b) adding 1.0 equiv.

(NH4)4Ce(SO4)4·4H2O; (c) adding 1.0 equiv. Vitamin C.

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The reversible transformations were also monitored by UV-Vis. Upon addition of

1.0 equiv. of (NH4)4Ce(SO4)4·4H2O, the peak around 630 nm was observed,

concomitant with the obvious change in color, resulting from oxidation of Fc to Fc+.

With the addition of Vitamin C, the peak vanished and the color of solution returned

to the original Fc state.

3.7 Calculation Method for Binding Affinity

The molecular dynamics/quantum mechanics/continuum solvent model (MD/QM/

CSM) method was used to calculate binding affinities in aqueous solution between

β-CD and the drugs, including GEM, p-coumalic acid and DOX. Briefly, we first

carried out MD simulations using Amber12 software to sample the large number of

conformations of the β-CD inclusion complex. Then, we categorized similar

conformations along the MD trajectory based on coordinates of the O atoms at 2, 3, 4,

6 positions of β-CD as well as the heavy atoms of the guest molecules. The threshold

of the RMS difference for cluster analysis was set to ca.1.0 Å to generate 6~9 clusters.

Next, the conformations at local minima on the potential energy surface of the two

largest clusters were collected, which were subjected to further energy minimization.

Finally, the global minimum was identified and deemed as the representative

conformation of the β-CD complex, which served as the starting structure for further

binding free energy calculations.

The calculated free energy includes both the interaction between β-CD and the

guest molecules and that between the inclusion complex and the aqueous solution.

Based on thermodynamic cycle, the total binding free energy in aqueous solution is

partitioned as following,

aqu vacu solv

bind bind bindG G G∆ = ∆ + ∆ (1)

where vacu

bindG∆ and solv

bindG∆ are the binding free energy in vacuum and the change

of solvation free energy when the system is transferred from vacuum to aqueous

solution, respectively. The latter is calculated as the difference between the solvation

energy of the β-CD complex and those of the separated CD and guest,

( )solv solv solv solv

bind comp host guestG G G G∆ = − + (2)

The binding free energy in vacuum in Eq. (1), include the enthalpy and entropy

changes, vacu vacu vacu

bind bind bindG H T S∆ = ∆ − ∆ (3)

We first optimized the representative conformations of the β-CD complex, β-CD,

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and guest in the gas phase. Then these thermodynamic quantities are computed from

the PM3 frequency calculation.

Figure S8. Representative conformations of the β-CD inclusion complexes with (A) GEM, (B)

p-coumalic acid and (C) DOX, DOX cannot form the stable complexation with β-CD due to the

limitation of molecular size.

Table S3. Calculated binding affinities in aqueous solutions for the β-CD complexes.

System ∆H -T∆S ∆Gvacu ∆G

el ∆Gnp ∆G

solv ∆Gaqu

GEM/β-CD -10.9101 19.6548 9.7447 -2.9987 9.95 6.9513 15.696

p-coumalic

acid/β-CD -4.8616 14.4883 9.6267 -2.6326 5.66 3.0274 12.654

According to the following equation,

lnaquG RT K∆ = − (4)

The higher aquG∆ , the lower K (binding affinity). Therefore, Compared with

p-coumalic acid, the relatively lower binding affinity between GEM and β-CD was

theoretically obtained, indicating that GEM was more prone to pass through β-CD’s

cavity by diffusion under the concentration gradient.

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4. Control Experiments ⅠⅠⅠⅠ

4.1 Preparation of MSNPs 2

Scheme S5. Synthetic procedure for preparing MSNPs 2.

4.1.1 Synthetic procedure of heptakis(6-deoxy-6-amino)-β-cyclodextrin

(NH2-β-CD)

Scheme S6. Synthesis of NH2-β-CD.

The synthesis process of NH2-β-CD was according to the previously literature.1 The

NMR and MS measurements were used to characterize NH2-β-CD. 1H NMR (NH2-β-CD, 300 MHz, D2O) δ 4.20 (t, J=7.0Hz, 7H, H-1), 3.83 (m, 7H,

H-6’), 3.57 (m, 14H, H-3, 5), 3.44 (dd, 14H, H-2, 4), 3.26 (dd, 7H, H-6). 13

C NMR (NH2-β-CD, 75 MHz, D2O) δ 100.94 (C-1), 81.69 (C-4), 71.67-71.15 (C-2,

C-3, C-5), 42.9 (C-6).

MS (NH2-β-CD, ESI): m/z calcd forC42H77N7O28: 1128.62; found: 1129.58 [M+H]+.

4.1.2 Preparation of MSNPs 2

The synthetic procedure of MSNPs 2 was as the same as that for MSNPs 1, except

for employing NH2-β-CD (equal mol.% to NH2-Fc-β-CD) to replacing NH2-Fc-β-CD.

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The FTIR (Figure S9) and 13C SS-NMR (Figure S10) spectra proved the successful

construction of MSNPs 2.

Figure S9. FTIR spectra of (a) MSNs; (b) MSNs-PTPC; (c) MSNs-ABP; and (d) MSNPs 2

(without GEM and DOX).

Figure S10. 13C SS-NMR spectra of (A) MSNs-PTPC, (B) MSNs-ABP, and (C) MSNPs 2

(without GEM and DOX).

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5. Control Experiments ⅡⅡⅡⅡ

5.1 Preparation of MSNPs 3

Scheme S7. Synthetic procedure for preparing MSNPs 3.

5.1.1 Synthetic procedure of mono-2-O-[[1-(ferrocenylmethyl)-1H-1,2,3-triazole

-4-yl]methyl]-mono-(6-deoxy-6-amino)-β-cyclodextrin

(mono-NH2-Fc-β-CD)

Scheme S8. Synthesis of mono-NH2-Fc-β-CD.

Compound 7: To a solution of Fc-β-CD (2.49 g, 1.762 mmol) in water (20 mL)

was added sodium hydroxide solution (2 mL, 8.21 M), and then the reaction was

stirred for 1 h in ice bath. Next, p-toluenesulfonyl chloride (0.727 g, 3.52 mmol) in

acetonitrile (3 mL) was added dropwise within 15 min and reacted for 4 h. After

removing the precipitate, the pH of filtrate was adjusted by HCl (aq. 10 wt%) to 7, the

reaction mixture was cooled to 4 ℃ and kept overnight. The precipitate was filtered,

recrystallized from distilled water and dried in vacuo to afford mono-2-O-

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[[1-(ferrocenylmethyl)-1H-1,2,3-triazol-4-yl]methyl]-mono-(6-O-(p-tolylsulfonyl))-β-

cyclodextrin (Intermediate Compound 1). To a solution of Intermediate Compound 1

(0.334 g, 0.259 mmol) in DMF (3.3 mL) was added sodium azide (118 mg, 1.82

mmol). After reaction for 6 h at 80 ℃, the mixture was poured into acetone (45 mL)

and the crude product was filtered, washed with ethanol (20 mL×2), purified by

recrystallized from distilled water, and dried in vacuo to give Compound 7 (0.262 g,

yield 12.8%). 1H NMR (300 MHz, DMSO-d6) δ 8.05(s, 1H, H5-C2HN3), 5.71 (m, 12H, OH), 5.26

(d, J =9.3 Hz, 2H, CHN), 4.98-4.71 (m, 9H, H-1, CHO), 4.52 (m, 6H, OH), 4.35 (brs,

2H, HCp), 4.23 (s, 5H, HCp’), 4.20 (s, 2H, HCp), 4.00-3.32 (m, 69H, H-2~6, HDO). 13

C NMR (75 MHz, DMSO-d6) δ 143.70 (C4-C2HN3), 122.83 (C5-C2HN3), 103.10

(C-1), 100.46 (C-1A), 83.02 (C-4), 74.58-73.73 (C-2, C-3, C-5), 68.39 (CCp’),

67.61(CCp), 60.61 (C-6), 52.5 (C-6A), 49.31 (CH2N).

mono-NH2-Fc-β-CD: To a solution of Compound 7 (220 mg, 0.153 mmol) in

anhydrous DMF (4 mL) was added triphenylphosphine (636 mg, 2.42 mmol). The

reaction was stirred for 1 h at room temperature under nitrogen atmosphere. Next, the

concentrated aqueous ammonia (2.25 mL, 28 wt%) was added within 5 min. After

being stirred at room temperature for 18 h, the reaction mixture was concentrated in

vacuo, and the residue was poured into ethanol. The precipitate was filtered and

evaporated in vacuo to give mono-NH2-Fc-β-CD (153 mg, yield 71%). For NMR

measurement, the mono-NH2-Fc-β-CD was converted to amine salt by addition of a

dilute solution of DCL (down to pH 6). 1H NMR (300 MHz, D2O) δ 7.72 (s, 1H, H5-C2HN3), 5.71 (m, 12H, OH), 5.25 (d, J

= 9.3 Hz, 2H, CHN), 5.12 (m, 9H, H1, CHO), 4.52 (m, 6H, OH), 4.42 (brs, 9H, HCp,

HCp’), 4.04 (t, J=9.4Hz, 7H, H-1), 3.81 (m, 7H, H-6’), 3.52 (m, 14H, H-3, 5), 3.43 (dd,

14H, H-2, 4), 3.26 (dd, 7H, H-6). 13

C NMR (75 MHz, D2O) δ 101.29 (C-1), 81.83 (C-4), 80.31 (C-2A), 71.82-71.27

(C-2, C-3, C-5), 70.81 (C-3A), 39.92 (C-6), 30.07 (C-6A).

5.1.2 Preparation of MSNPs 3

The synthetic procedure of MSNPs 3 was as the same as that for MSNPs 1, except

for employing mono-NH2-Fc-β-CD (equal mol.% to NH2-Fc-β-CD) to replacing

NH2-Fc-β-CD. The FTIR and 13C SS-NMR spectra of MSNPs 3 were similar to

MSNPs 1 and not provided here.

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REFERENCES

(1) Ashton, P. R.; Koniger, R.; Stoddart, J. F.; Alker D.; Harding, V. D. Amino Acid

Derivatives of β-Cyclodextrin. J. Org. Chem. 1996, 61, 903-908.