A Nanoparticle based chromogenic chemosensor for the ... › suppdata › cc › b8 › b813423e › b813423e.pdf · 4. Figure S2: pS5 5. Figure S3: pS6 6. Figure S4: pS6 7. Figure

A Nanoparticle based chromogenic chemosensor for the simultaneous detection of multiple analytes.

Narinder Singh, Ray C. Mulrooney, Navneet Kaur and John F. Callan*.

School of Pharmacy, The Robert Gordon University, Aberdeen, Scotland, U.K. AB10 1FR Email: [email protected]

1. Experimental: Synthesis of 1 and 2. pS2-pS3 2. Experimental: Equipment and parameters. pS4 3. Figure S1: pS5 4. Figure S2: pS5 5. Figure S3: pS6 6. Figure S4: pS6 7. Figure S5: pS7 8. Figure S6 pS8 9. Figure S7 pS9 10. Figure S8 pS9 11. Figure S9 pS10 12. Figure S10 pS10 13. Figure S11 pS11 14. Figure S12 pS11

Supplementary Material (ESI) for Chemical CommunicationsThis journal is (c) The Royal Society of Chemistry 2008

2

1. Experimental: Synthesis of 1 and 2. Materials and Reagents.

Chemicals were purchased from Aldrich Co. and used as received without further

purification. Green emitting CdSe-ZnS QD’s were purchased from Evident

Technologies, New York (product No ED-C10-TOL-0545). Receptor 11 and its

disulfde 32 were prepared following literature procedures. Their 1H nmr spectra are

provided in Figures S11 and S12 respectively.

Synthesis of QD-Receptor conjugate (2).

The QD-Receptor conjugate was prepared with the ligand exchange reaction

developed by Tomasulo et al.3 A solution of CdSe/ZnS core based QDs (0.5 mL, 27

nmol) was added to receptor 1 (2.3 g, 0.01 mol) in dry chloroform. The reaction was

allowed to reflux for 24 h. Upon completion of reaction, the solvent was removed

under reduced pressure. The crude mass was suspended in acetonitrile (5 ml) and

centrifuged at 12,500 rpm for 5 min. The supernatant solution was decanted off and

the solid was again suspended in fresh acetonitrile. This step was repeated twice and

the product was vacuum dried to obtain pure 2 as an orange coloured powder (0.02 g).

The QD and QD conjugate concentration was determined by a literature method.4

Cation recognition studies.

The cation binding ability of 2 was determined by preparing solutions containing 4.0

X 10-8 M of QD-receptor conjugate and 50 μM of a particular metal salt in THF:H2O

(8:2, v/v) HEPES buffered solution (pH = 7.0 ± 0.1). The absorption spectrum of each

solution was recorded. The cation recognition behavior of QD-receptor conjugate for

the binding of a particular cation was evaluated from the changes in absorption

spectrum of receptor upon addition of that metal salt.

QD-receptor conjugate vs. Metal ion titration

Volumetric flasks were taken each containing 4.0 X 10-8 M of 2 along with varied

amounts of a particular metal salt in THF : H2O (8:2, v/v) HEPES buffered solution

(pH = 7.0 ± 0.1). The solutions were shaken thoroughly and their absorption spectra

were recorded.


3

pH titration

The solutions were prepared under similar conditions as were used for QD-receptor

conjugate vs. metal ion titration experiment, except that the solutions were not

buffered at a fixed pH value.


4

2. Experimental: Equipment and Parameters UV-Vis measurements were recorded on an Agilent UV-Vis Spectrometer using 10

mm quartz cuvettes. NMR spectra were recorded on a Bruker Ultrasheild 400 MHz.

1H NMR samples were prepared by dissolving 5 mg of sample in 1.0 mL of CDCl3..

Chemical shifts are reported in parts per million (δ) downfield of TMS. Particle size

distributions were recorded on a Malvern NanoZS instrument at 25oC in a 10 mm

cuvette using a He-Ne laser of 633 nm. The average size is the average of 20

independent experiments and the standard deviation is taken as the error.

Transmission Electron Micrographs were recorded with a JEOL-JEM 2011 electron

microscope operating at 200 kV


5

Figure S1: Absorption spectra of 1 in the presence of various metal ions. [1] = 1 x 10-6 M; [ion] = 50 μM; in a 80% THF / 20% 0.01 M HEPES buffer solution at pH = 7.0.

0

0.5

1

1.5

2

2.5

275 325 375 425 475 525

Wavelength (nm)

Abs

orba

nce

Host Na(I)K(I) Ca(II)Mg(II) Mn(II)Fe(III) Co(II)Ni(II) Cu(II)Zn(II) Ag(I)Cd(II)

Figure S2: Absorption spectra of 3 in the presence of various metal ions. [3] = 1 x 10-6 M; [ion] = 50 μM; in a 80% THF / 20% 0.01 M HEPES buffer solution at pH = 7.0.

0

0.5

1

1.5

2

2.5

250 300 350 400 450 500

Wavelength (nm)

Abs

orba

nce

Host Na(I)K(I) Ca(II)Mg(II) Mn(II)Fe(III) Co(II)Ni(II) Cu(II)Zn(II) Ag(II)Cd(II)


6

Figure S3: Expansion of the aromatic region for Receptor 1 (A) and QD-receptor

conjugate 2 (B).

Figure S4: Absorption spectrum of 2 recorded in THF showing the visible region. The first exciton peak is the broad absorption centered at 510 nm. [2] = 2.0 x 10-6. M.

0.05

0.15

0.25

0.35

425 475 525 575 625 675 725 775

Wavelength (nm)

Abs

orba

nce


7

Figure S5: Dynamic Light Scattering measurements of CdSe/ZnS QD’s (top) and 2 (bottom). Solvent = THF, [CdSe/ZnS QD’s] = 1.0 x 10-6 M, [2] = 1.0 x 10-6 M.

0

5

10

15

20

1 10 100 1000 10000

Volu

me

(%)

Size (d.nm)

Size Distribution by Volume

0

10

20

30

40

1 10 100 1000 10000

Volu

me

(%)

Size (d.nm)

Size Distribution by Volume


8

Figure S6: TEM image of 2.


9

Figure S7: UV/Vis - pH titration of 2. [2] = 4 x 10-8 M in a 80% THF / 20% H2O solution. Inset lists the pH values tested.

0

0.2

0.4

0.6

0.8

1

1.2

290 315 340 365 390 415 440

Wavelength (nm)

Abs

orba

nce

3.45 3.653.97 4.785.53 6.16.75 7.27.52 8.18.31 8.578.73 8.939.15 9.459.7 9.9510.22 10.6510.89 10.9611.25 11.812.05 12.35

Figure S8: Plot of absorbance intensity against pH for 2. [2] = 4.0 x 10-8 M in a 80% THF / 20% H2O solution.

0

0.2

0.4

0.6

0.8

1

1.2

0 1 2 3 4 5 6 7 8 9 10 11 12 13

pH

Abs

orba

nce

@ 3

82 n

m


10

Figure S9: Competition study of 2 for Cu(II) in the presence of Fe(II). The values shown in the inset are the μM concentrations of Cu(II) with Fe(II) being present at 25% of this concentration. Solutions prepared in a 80% THF / 20% 0.01 M HEPES buffer solution at pH = 7.0. [2] =4.0 x 10-8 M.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

250 275 300 325 350 375 400 425 450 475 500

Wavelength (nm)

Abs

orba

nce

Host 2.5 5

7.5 10 12.5

15 17.5 20

22.5 25 27.5

30

Figure S10:Competition study of 2 for Fe(III) in the presence of Cu(II). The values shown in the inset are the μM concentrations of Fe(III) with equimolar concentration of Cu(II). Solutions prepared in a 80% THF / 20% 0.01 M HEPES buffer solution at pH = 7.0. [2] =4.0 x 10-8 M.

00.20.40.60.8

11.21.41.61.8

2

230 255 280 305 330 355 380 405 430 455 480 505 530

Wavelength (nm)

Abs

orba

nce

0 2.55 7.510 12.515 17.520


11

Figure S11: 1H NMR spectra of 1 in CDCl3.

Figure S12: 1H NMR spectra of 3 in d6-DMSO


12

Table 1. Illustrating the dA/Ao ratios for various metal ions at λmax = 325 and 410 nm.

dA/Ao 325

dA/Ao 410

Na(I) 0.164 1.025 K (I) 0.086 1.140 Mg(II) 0.029 1.099 Ca(II) 0.171 1.073 Mn(II) 0.509 1.092 Fe(III) 1.500 9.716 Co(II) 0.509 3.271 Ni(II) 0.159 2.748 Cu(II) 0.342 22.717 Zn(II) 0.259 2.977 Ag(I) 0.194 2.822 Cd(II) 0.261 2.410

The reported values are the average of independent determinations and are within error range of ± 5%.


13

References 1 F. Tisato, F. Refosco, U. Mazzi, G. Bandoli, and M. Nicolini, J. Chem. Soc., Dalton Trans. 1987, 1693-1699. 2 D. Wang, A. Behrens, M. Farahbakhsh, J. Gätjens, and D Rehder, D. Chem. - Eur. J, 2003, 9, 1805-1813. 3 M. Tomasulo, I. Yildiz, S.L. Kaanumalle, and F.M. Raymo, Langmuir, 2006, 22, 10284-10290. 4 W.W.Yu, L. Qu, W. Guo, X. Peng, Chem. Mater., 2003, 15, 2854-2860.


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A Nanoparticle based chromogenic chemosensor for the ... › suppdata › cc › b8 › b813423e › b813423e.pdf · 4. Figure S2: pS5 5. Figure S3: pS6 6. Figure S4: pS6 7. Figure