Supporting Information

Postmodification Strategy to Modulate the Photoluminescence of Carbon Dots

from Blue to Green and Red: Synthesis and Applications

Min Zhenga*, Lihong Qiaoa, Ya Sua, Pengli Gaoa, and Zhigang Xieb*

a School of Chemistry and Life Science, Advanced Institute of Materials Science,

Changchun University of Technology, 2055 Yanan Street, Changchun, Jilin 130012,

P. R. China

b State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of

Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun,

Jilin 130022, P. R. China

*Corresponding author E-mail: zhengm@ciac.ac.cn (Min Zheng); xiez@ciac.ac.cn

(Zhigang Xie)

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry B.This journal is © The Royal Society of Chemistry 2019

Experimental Section

Materials. All reagents were purchased from commercial sources and used without

further treatment.

Characterizations.

Transmission electron microscope (TEM) images were carried out on a JEOL

JEM–1011 (Japan) at the accelerating voltage of 100 kV. High-resolution TEM (HR-

TEM) images were recorded with a FEI-TECNAI G2 transmission electron

microscope operating at 200 kV. X-Ray photoelectron spectra (XPS) were obtained

on a Thermo Scientific ESCALAB 250 Multitechnique Surface Analysis. Fourier

Transform Infrared (FT-IR) spectra were recorded on a Bruker Vertex 70

spectrometer. Fluorescence emission spectra were recorded on a PerkinElmer LS-55

phosphorescence spectrophotometer. UV-Vis absorption spectra were conducted on

Shimadzu UV-2450 spectrophotometer. The Edinburgh FLS 920 spectrometer with a

calibrated integrating sphere was used to measure absolute Quantum Yield.

MTT [3-(4,5-dmethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay cell

lines and cell culture

HeLa cell lines were purchased from the Institute of Biochemistry and Cell Biology,

Chinese Academy of Sciences, Shanghai, China. HeLa cells were grown in

Dulbecco’s modified Eagle’s medium (DMEM, GIBCO) supplemented with 10%

heat-inactivated fetal bovine serum (GIBCO), 100 U/mL penicillin and 100 μg/mL

streptomycin (Sigma), and the culture medium was replaced once very day.

Cellular uptake

Cellular uptake by HeLa cells was examined using a confocal laser scanning

microscope. HeLa cells were seeded in 6-well culture plates (a sterile cover slip was

put in each well) with a density of 5 x 104 cells per well and allowed to adhere for 24

h. After that, the cells were treated with CD-B, CD-V and CD-A (2 mg/mL) for 1 h

at 37 °C, respectively. After that, the supernatant was carefully removed and the

cells were washed three times with PBS. Subsequently, the cells were fixed with 800

μL of 4% formaldehyde in each well for 20 min at room temperature and washed

twice with PBS again. The slides were mounted and observed with a confocal laser

scanning microscope imaging system (Zeiss LSM 780).

In vivo fluorescence imaging.

Kunming male mice were obtained from Jilin University, China (56–84 days, 20–25

g) and maintained under required conditions. Their use for this study was approved

by the Animal Ethics Committee of Jilin University. Before the subcutaneous

injection, the back area of the mouse was shaved to minimize autofluorescence. The

mouse were subcutaneously injected with CD-V and CD-A (2 mg/mL, 25 μL) on

their back after being anesthetized by intraperitoneal injection of 1% pentobarbital.

The mouse was imaged by using a Maestro in vivo optical imaging system

(Cambridge Research & Instrumentation, Inc., Woburn, Massachusetts). Various

excitations including green (503–555 nm) and yellow (575–605 nm) light were

applied during imaging.

Fig. S1 (A) The photo of the six samples under UV light on the eighth day. (B) 3D

PL spectra of B vs time.

400 500 600 7000

60

120

180

Inte

nsity

(a.u

.)

Wavelength (nm)

20 min 20 min 40 min 40 min 60 min 60 min

60 oC

400 500 6000

50

100

150In

tens

ity (a

.u.)

Wavelength (nm)

20 min 20 min 40 min 40 min 60 min 60 min

40 oC

350 400 450 500 550 600 6500

255075

100125150175200

Inte

nsity

(a.u

.)

Wavelength (nm)

20 min 20 min 40 min 40 min 60 min 60 min

RT

350 400 450 500 550 600 6500

200

400

600

800

Inte

nsity

(a.u

.)

Wavelength (nm)

20 min 20 min 40 min 40 min 60 min 60 min

80 oC

A B

C D

Fig. S2 PL spectra changes of the reaction mixtures of CD-B with VC at RT (A), 40

oC (B), 60 oC (C), and 80 oC (D), the emissions were excited at 300 nm and 440 nm,

respectively.

7 8 9 10 11 12 13Diameter (nm)3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0Diameter (nm) 5.0 5.5 6.0 6.5 7.0 7.5Diameter (nm)

A B C

Fig. S3 Size distribution of CD-B (A), CD-V (B) and CD-A (C) determined by TEM

images.

4000 3500 3000 2500 2000 1500 1000 500

Tran

smitt

ance

Wavenumbers (cm-1)

C=N

4000350030002500200015001000 500

Tran

smitt

ance

Wavenumbers (cm-1)4000350030002500200015001000 500

C-OTran

smitt

ance

Wavenumbers (cm-1)

C=O

A B C

Fig. S4 FT-IR spectrum of CD-B (A), CD-V (B) and CD-A (C).

0 10 20 30 40

IRF CD-V

Inte

nsity

Time (ns)

500 550 600 650 700 7500

20

40

60

80

100

Inte

nsity

(a.u

.)

Wavelength (nm)

460 nm 480 nm 500 nm 520 nm 540 nm 560 nm

0 10 20 30 40

Inte

nsity

(a.u

.)

Time (ns)

IRF CD-A

A B

C D

400 450 500 550 600 650 700

0

200

400

600

800

1000In

tens

ity (a

.u.)

Wavelength (nm)

360 nm 380 nm 400 nm 420 nm 440 nm 460 nm 480 nm

Fig. S5 (A) PL spectra of CD-V under the excitation of 360-480 nm. (B) PL decay

curve of CD-V. (C) PL spectra of CD-A under the excitation of 460-560 nm. (D) PL

decay curve of CD-A.

Table S1 A series of control experiments of CD-B with VC.

Samples CD-B (mg/mL) VC (mg/mL)

A 0.5 0.5

B 0.05 0.5

C 0.005 0.5

D 0.1 0.1

E 0.1 0.25

F 0.1 0.5