Enhancing Cell Nucleus Accumulation and DNA Cleavage Activity of
Anti-Cancer Drug via Graphene Quantum Dots
Chong Wang,1 Congyu Wu,2 Xuejiao Zhou2, Ting Han2, Xiaozhen Xin,1Jiaying Wu1, Jingyan
Zhang,1* Shouwu Guo2*
Figure S1. DNA cleavage by DOX (10 μM) and GQDs for 1 and 2 h of reactions at
37 ℃.The first two lanes in the gels are the controls of DNA alone and DNA with NaBH4 (25
mM). The Table on the right side summarizes the percentages of the nicked and linear DNA
generated under different reaction conditions.
Figure S2. AFM images (top panel) acquired in air under tapping mode and the height
profiles (down panel) of (a) GQDs and (b) DOX/GQD conjugates. Scale bar: 0.5 μm.
Figure S3. Zeta potential of the GQDs (120 μg mL-1) (red line) and DOX (8 μM) with GQDs
(120 μg mL-1) (black line).
Figure S4. Fluorescence emission spectra of the DOX (5 μM) mixed with GQDs (75 μg mL−1)
in PBS buffer (a) and in cellular culture medium (b). Black lines in both figures are the
fluorescence spectra of DOX alone. The addition of GQDs quenched the fluorescence, and the
mixture was maintained at room temperature for 1, 6, 12, 24, and 36 h. c) Fluorescence
emission spectra of DOX (10 μM), and DOX with GQDs (50 μg mL-1) in PBS buffer (pH 7.4)
with different NaCl: 10 (black), 50 (red) and 100 mM NaCl (blue). d) Fluorescence emission
spectra of the DOX and DOX/GQDs in the solution with different pH values: 7.4 (black), 5
(red) and 2 (blue). Excitation wavelength was 500 nm.
Figure S5. Left: Fluorescence emission spectra of the DOX (20 μM) (black), DOX (20 μM)
with GQDs (100 μg mL-1) (red) in aqueous solutions, and the mixture of DOX and GQDs
after the addition of 50% alcohol (blue). Excitation wavelength is 500 nm. Right: the
molecular model of the DOX/GQD conjugate.
Figure S6. Cell viability of MGC-803 cells after 24 h exposure to 2 μM of DOX and different
concentrations of GQDs at 37 ℃. Zero spot indicates without GQDs corresponding to the
point that circled in the inset. Inset is the cell viability of MGC-803 cells after 24 h of
incubation with different concentrations of DOX alone at 37 ℃.
Figure S7. Cell viability of MCF-7 (a) and MGC-803 cells (b) after 24 h of exposure to
different concentrations of GQDs at 37 ℃.
Figure S8. CLSM images of the MCF-7 cells after the incubation with GQDs (15 µg mL-1),
DOX (1µM), and DOX/GQDs with the same DOX and GQD concentrations for 4 h.
Excitation wavelength was 488 nm. The fluorescence intensities in the right figure were
generated by Image-Pro Plus program. Scale bar: 50 μm.
Figure S9. Fluorescence images of the MCF-7 cells after incubation with DOX (1 µM) and
different concentration of GQDs for 1h. a) bright-field images, b) fluorescence images of
nuclei stained by Hoechst 33258, c) fluorescence images of DOX at excitation wavelength of
510 nm, and d) merges of a, b, c. Scale bar: 50 μm.
Figure S10. MCF-7 cells were pretreated with fresh medium, chlorpromazine, Filipin Ⅲ and
NaN3 and then incubated with DOX (1 µM) and GQDs (20 µg mL-1) for 4 h. Row a,
bright-field images, Row b, fluorescence images of DOX at excitation wavelength of 510 nm;
Row c, fluorescence images of the Hoechst 33258 stained nuclei, and row d are merges of a, b,
and c. Scale bar: 50 μm.
Figure S11. Top: Fluorescence images of the MCF-7 cells incubated with DOX (1µM ) and
GQDs (20 µg mL-1) for 1 h, then cultured in a fresh medium for 45 min, 105 min and 3 h.
Bottom: the merges of the fluorescence images with the bright field images. Scale bar: 25 μm.
Figure S12. MCF-7 cells were incubated first with the medium containing DOX (1µM) for 8
h (control), and then cultured in the fresh media without DOX, but with different
concentration of GQDs (0, 15, and 60 µg mL-1) for 1 and 16 h. Scale bar: 25 μm.
Figure S13. Bright field (top) and DOX fluorescence (bottom) images of the MCF-7/ADR
cells incubated with different concentration of GQDs for 6 h. Scale bar: 25 μm.