Green synthesis of multimodal ‘OFF-ON’ switchable MRI/optical

probes

J. Gallo1*, N. Vasimalai2, M.T. Fernandez-Arguelles2, M. Bañobre-López1*

1 Advanced (magnetic) Theranostic nanostructures group, INL – International Iberian Nanotechnology Laboratory,

Av. Mestre José Veiga, 4715-330 Braga, Portugal 2 Life Sciences department, INL – International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga, 4715-

330 Braga, Portugal

Electronic supporting information

Electronic Supplementary Material (ESI) for Dalton Transactions.This journal is © The Royal Society of Chemistry 2016

Table S1. CQDs characterisation summary.

Parameters Results

Excitation/emission

maximum

λex: 370 nm

λem: 462 nm

Stokes shift 92 nm

FWHM 145 nm

Size (TEM) 4.3 ± 0.5 nm

d-spacing (TEM) 0.32 nm

D band

G band (Raman)

1340.6 cm-1

1567.5 cm-1

ID/IG (Raman) 1.44

Zeta potential -16.3 mV

Quantum yield

(quinine sulfate std)

38.31 %

Figure S1. (a) UV-vis and (b) emission spectra of CQDs (λex/λem = 370 nm/462 nm). Inset:

photographs of CQDs water solutions (i) day light (ii) UV light (320 nm).

Figure S2. Emission spectra of CQDs under different excitation wavelengths. Left, from 290 to

370 nm, and right, from 370 to 600 nm.

400 500 600 700

0.0

2.0x106

4.0x106

6.0x106

8.0x106

1.0x107

Inte

nsit

y

Wavelength (nm)

290 nm

300 nm

310 nm

320 nm

330 nm

340 nm

350 nm

360 nm

370 nm

400 500 600 700

0.0

2.0x106

4.0x106

6.0x106

8.0x106

1.0x107

Inte

nsit

y

Wavelength (nm)

370 nm

380 nm

390 nm

400 nm

410 nm

420 nm

430 nm

440 nm

450 nm

460 nm

470 nm

480 nm

490 nm

500 nm

510 nm

520 nm

530 nm

540 nm

550 nm

560 nm

570 nm

580 nm

590 nm

600 nm

400 500 600 700

0.0

2.0x106

4.0x106

6.0x106

8.0x106

1.0x107

Inte

nsit

y

Wavelength (nm)

200 300 400 500 600 700

0

1

2

3

4

5A

bso

rban

ce

Wavelength (nm)

n-

(ii) (i)

(a) (b)

Figure S3. FT-IR spectrum of CQDs

Figure S4. Raman spectrum of CQDs showing D and G bands.

4000 3500 3000 2500 2000 1500 1000 5000.0

0.2

0.4

0.6

0.8

1.0

33

90

29

66

11

14

14

02

C-O

C-H

C=O

16

02

C-H

Tra

ns

mit

tan

ce

(%

)

Wavenumber (cm-1)

O-H

1000 1200 1400 1600 1800

Inte

ns

ity

(a

.u.)

Raman shift (cm-1)

D G

Figure S5. Left, overview SEM image of MnO2_CQDS nanosheets deposited on a silicon

surface. Right, high resolution TEM image of CQDs.

Figure S6. High resolution TEM image of MnO2_CQDs showing the polycrystalline nature of

the sample.

Figure S7. SAED pattern obtained on a sample of MnO2_CQDs and the assignment of the

structure.

Figure S8. Energy dispersive X-ray spectra (EDXS) of a MnO2_CQDs sample showing clear

peaks from Mn, O and C.

Figure S9. Raman spectra and tentative assignment of the peaks of a sample of MnO2_CQDs.

30 40 50 60 70 80 90

MnO2-CQDs

Inte

nsity (

a. u

.)

2 (º)

Figure S10. XRD diffractogram of MnO2_CQDs nanosheets showing a pattern matching the

JCPDS pattern of MnO2 (JCPDS 44-0141, J.Phys.Chem.C, 2015, 119, 6604). The baseline signal

has been subtracted by adjacent-averaging smoothing method considering 20 anchor points

connected by Spline interpolation.

Figure S11. FT-IR spectra of MnO2-CQDs nanocomposites.

Figure S12. TGA curve showing the mass loss from MnO2 nanosheets (after solvent loss) against

temperature.

0

0.2

0.4

0.6

0.8

1

1.2

4008501300175022002650310035504000

Wavelength/cm-1

ν(OH)str

ν(OH)bendv (C=O)

ν(Mn-O)

Figure S13. TGA curve showing the mass loss from MnO2-CQDs nanocomposites (after solvent

loss) against temperature.

Figure S14. Left, white light image of water solutions of MnO2_CQDs nanocomposites (left

column) before (upper) and after (bottom) reduction with GSH, and CQDs (bottom right column);

center, green channel fluorescence of the same samples; right, overlay image. MnO2_CQDs

concentration: 1 and 3, 0.9 mg Mn/mL; 2 and 4, 1.8 mg Mn/mL. CQDs concentration: 5, 0.9

mg/mL; 6, 1.8 mg/mL. GSH concentration 5 mM.

1 2

3 4 5 6

Figure S15. Left, evolution of the fluorescence spectra of a 11 µg Mn/mL solution of MnO2-

CQDs nanocomposites in completed (10% foetal bovine serum) DMEM medium upon the addition

of increasing concentrations of GSH (from 0 to1.80 mM). Right, evolution of the fluorescence at

443 nm versus the concentration of GSH.

Figure S16. Investigation of the de-quenching mechanism of CQDs PL from MnO2 nanosheets in

the presence of increasing concentrations of H2O2.

Figure S17. A, T1-weigthed MR image of different phantoms: First column, H2O only (top) and

MnO2_CQDs in H2O (bottom). Second column, DMEM only (top) and MnO2_CQDs in DMEM

(bottom). Rest of columns, MnO2_CQDs in DMEM or H2O (top) and MnO2_CQDs in DMEM or

H2O after the addition of Glc, Tyr, or GSH (bottom). B, Signal intensity analysis from phantoms

in A showing a clear OFF-ON transition both in water and DMEM cell culture media.

Figure S18. Evolution of the T1-weigthed signal intensity of a phantom containing 6 ug Mn/mL

of MnO2-CQDs in water (orange) or completed DMEM cell culture media (blue) as a function of

the concentration of GSH in the solution.

Figure S19. r1 and r2 relaxivity plots of MnO2_CQDs nanocomposites in water before (A) and

24h after (B) the addition of 100 mM GSH.

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70

I Sam

ple

/IB

lan

k

mM GSH

DMEM

H2O

Figure S20. Viability test of A549 cells incubated for 4h at 37oC and 5% CO2 in the presence of

increasing concentrations of MnO2-CQDs (0 to 100 µg Mn/mL).

Figure S21. Representative fluorescence confocal images of A549 cells incubated only in

completed DMEM cell culture media (A), completed cell culture media plus 1.8 mg/mL of

turmeric CQDs (B), and completed cell culture media plus 1.8 mg Mn/mL of MnO2_CQDs

nanocomposites (C).

0

20

40

60

80

100

120

140

0 2 5 10 25 50 75 100

Cytotoxicity MnO2_CQDs nanosheets