Graphene Quantum Dots-Band-Aids Used for Wound Disinfection

Supporting information Graphene Quantum Dots-Band-Aids Used for Wound Disinfection Hanjun Sun, Nan Gao, Kai Dong, Jinsong Ren, and Xiaogang Qu* Laboratory of Chemical Biology, Division of Biological Inorganic Chemistry, State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, University of Chinese Academy of Sciences, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China.

Figure S1. (A) PL spectra of the GQDs at different excitation wavelengths; (B) Normalized photoluminescence spectra of the GQDs; (C) UV-Vis absorption spectra of the GQDs; (D) FT IR spectra of GQDs; (E) XPS analysis surveys of GQDs; The XPS C1s analysis of GQDs. The optical properties of GQDs were studied by UV-vis absorption and photoluminescence (PL) spectroscopy. As shown in Figure S1A and S1B, the GQDs exhibited maximum excitation and emission wavelengths near 320 and 500 nm, respectively. For the UV-vis absorption of GQDs (Figure S1C), a typical absorption peak at ca. 270 nm was observed, and the strong background absorption below ca. 320 nm was assigned to the π π* transition of aromatic sp 2 domains. 1, 2 Fourier transform infrared (FT-IR) spectroscopy and X-Ray photoelectron spectroscopy (XPS) were used to discern the chemical structural variation of GQDs. As shown in Figure S1D, stretching vibrations of C-OH at 3438 cm -1, vibrations of OH at 1131 cm -1 -C=O at 1715 cm -1 and -C=C- at 1610 cm -1 were observed for GQDs. 2-4 Furthermore, the XPS of the GQDs showed three types of carbons: graphitic carbon

(C=C and C-C), oxygenated carbon (C=O and C-O-C) and nitrogenated carbon (C-N). 2-4 The nitrogen of GQDs originated from HNO 3 oxidation during the preparation (Figure S1E and S1F), which were consistence with the previous works. 2-4

Figure S2. GQDs peroxidase-like activity is dependent on temperature, ph, GQDs and H 2 O 2 concentration. (A) Experiments were carried out using 75 μg/ml GQDs in a reaction volume of 0.5 ml in 25 mm Na 2 HPO 4 buffer (ph=4.0), and 50 mm H 2 O 2, with 2.5 mm ABTS as substrate. (B) Experiments were carried out using 75 μg/ml GQDs in a reaction volume of 0.5 ml in 25 mm Na 2 HPO 4 buffer (37 C), and 50 mm H 2 O 2, with 2.5 mm ABTS as substrate at different ph. (C) Experiments were carried out using different concentration of GQDs in a reaction volume of 0.5 ml in 25 mm Na 2 HPO 4 buffer (ph=4.0, 37 C), and 50 mm H 2 O 2, with 2.5 mm ABTS as substrate. (D) Experiments were carried out using 75 μg/ml GQDs in a reaction volume of 0.5 ml in 25 mm Na 2 HPO 4 buffer (ph=4.0, 37 C), different concentration of H 2 O 2 with 2.5 mm ABTS as substrate. (E) Plots of the ABTS (2.5 mm) oxidation reaction rates with H 2 O 2 catalyzed by GQDs and GO versus the concentration of H 2 O 2. (F) Time course curves of using 50, 75, 100, 150 μg/ml GQDs or not in a reaction volume of 0.5 ml in 25 mm Na 2 HPO 4 buffer (ph=7.4, 37 C), and 50 mm H 2 O 2, with 2.5 mm ABTS as substrate.

Figure S3. (A) The chemiluminescence counts of 10 mm luminol oxidation by 50 mm H 2 O 2 without the addition of GQDs at ph 7.4; (B) The chemiluminescence counts of 10 mm luminol oxidation by 50 mm H 2 O 2 with the addition of 100 μg/ml GQDs at ph 7.4. The concentration of mannitol and NaN 3 were 10 mm. (C) Histograms of peak heights of (A) and (B), error bars were taken from five parallel experiments.

Figure S4. Representative digital images showed the influence of the catalytic activity of GQDs on the growth of Gram-positive (E. coli) and Gram-negative (S. aureus) bacteria. After co-incubation for 5 h at 37 C, the bacterial cells were plated in the appropriate medium (agar-lb for E. coli and S. aureus) and left to incubate for 8 h at 37 C. Gram-negative: E. coli alone (A); E. coli co-incubated with GQDs (100 μg/ml) (B); E. coli co-incubated with H 2 O 2 (1 mm) (C); E. coli co-incubated with GQDs (100 μg/ml) and H 2 O 2 (1 mm) (D); A significant decrease in bacterial population is observed in D. Gram-positive: S. aureus only (E); S. aureus co-incubated with GQDs (100 μg/ml) (F); S. aureus co-incubated with H 2 O 2 (1 mm) (G); S. aureus co-incubated with GQDs (100 μg/ml) and H 2 O 2 (10 mm) (H); In comparison, a significant decrease in the bacterial population (90%) can be observed in D and H.

Figure S5. Cytotoxicity studies of the GQDs (5 h post treatment) on both E.coli and S.aureus.

Figure S6. The survival rates of S. Epidermidis (A) treated with H 2 O 2 at different concentration co-incubation with or without GQDs (100 μg/ml). Optical density at 600 nm (OD 600nm ) of bacterial suspension treated with 100 μg/ml GQDs and 10 mm H 2 O 2 (S. Epidermidis) (B) at 2.5 h and 5 h. The original bacterial concentration is 1 10 6 cfu ml -1. * Significantly different (P < 0.05) from data o btained in the absence of GQDs, which indicated the enhanced antibacterial activity of H 2 O 2 by the catalysis of GQDs could inhibit the growth of S. Epidermidis bacteria significantly. (C) Cytotoxicity studies of the GQDs (5 h post treatment) on S. Epidermidis. Representative digital images showed the influence of the catalytic activity of GQDs on the growth of S. Epidermidis bacteria. After co-incubation for 5 h at 37 C, the bacterial cells were plated in the appropriate medium (agar-lb) and left to incubate for 8 h at 37 C. S. Epidermidis alone (D); S. Epidermidis co-incubated with GQDs (100 μg/ml) (E); S. Epidermidis co-incubated with H 2 O 2 (10 mm) (F); S. Epidermidis co-incubated with GQDs (100 μg/ml) and H 2 O 2 (10 mm) (G); A significant decrease in bacterial population is observed in G. S. Epidermidis (ATCC 12228) had been used as an in vitro model to test the antibacterial performance of this GQDs based system. As shown in Figure S6C, the GQDs didn t show any antibacterial activity at the concentration ranged from 10 to

500 μg/ml; Without addition of GQDs, just in the presence of a relative higher H 2 O 2 concentrations (1 M H 2 O 2 for S. epidermidis), the survival rate of S. epidermidis cells could be down to 10%. With the assistance of GQDs, the antibacterial ability of H 2 O 2 had been remarkably improved. Similar with S. aureus, just 10 mm H 2 O 2 could make the survival rate of S. epidermidis cells down to 10% (Figure S6A). In addition, the enhanced antibacterial activity of H 2 O 2 could also inhibit the growth of S. epidermidis (Figure S6B).

Figure S7. The effect of the GQDs based antibacterial system on the biofilm destory of S. aureus. (A) The remaining biofilms were quantified by crystal violet staining. (B) Pictures of crystal-violet-stained the remaining biofilms. (C) Pictures of the remaining biofilms before crystal-violet-stained.

Figure S8. The effect of the GQDs based antibacterial system on the biofilm formation of S. aureus. (A) The generated biofilms were quantified by crystal violet staining. (B) Pictures of crystal-violet-stained the generated biofilms. (C) Pictures of the generated biofilms before crystal-violet-stained.

Figure S9. Representative digital images showed the influence of the catalytic activity of GQDs on the growth of the surviving bacteria in the tissues of wound. After co-incubation for 300 min at 37 C, the bacterial cells were plated in the appropriate medium and left to incubate for 8 h at 37 C. Surviving bacteria in the tissues of wound treated with Saline+Blank-Band-Aid (A, E, I for the first day to third day, respectively.); Surviving bacteria in the tissues of wound treated with GQDs-Band-Aid (B, F, J for the first day to third day, respectively.); Surviving bacteria in the tissues of wound treated with H 2 O 2 +Blank-Band-Aid (C, G, K for the first day to third day, respectively.); Surviving bacteria in the tissues of wound treated with H 2 O 2 +GQDs-Band-Aid (D, H, L for the first day to third day, respectively.).

Table S1. The comparison of K m and V max with GQDs and GO. Sample K m (mm) V max (μm/s) GQDs 2.288 0.1563 GO 2.301 0.02205

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