Scheme 1. Schematic illustration of the Z-scheme ZnO/CDots/g-C3N4 composite for photoresponsivity bacteria-killing and acceleration of wound healing.

Fig. 1. (A) TEM image of the ZCCN. (B) Magnified TEM image of the ZCCN. (C) HRTEM image of CDots and ZnO embedded in g-C3N4 and corresponding FFT pattern of the CDots. (D) XRD patterns of the CCN, ZCCN and ZnO. (E) FT-IR spectra of the CCN, ZCCN and ZnO. (F) Surface ζ-potential of the CCN, ZCCN and ZnO.

Fig. 2. (A) XPS survey scan of the CCN and ZCCN. XPS high-resolution spectra of (B) C 1s peaks and (C) N 1s peaks obtained from CCN and ZCCN. XPS high-resolution spectra of (D) O 1s peaks and (E) Zn 2p peaks obtained from ZCCN.

Fig. 3. Photoresponsivity properties of different groups. (A) Photothermal curves under 15 min visible light irradiation. (B) Real-time infrared thermal images of different samples under visible light irradiation for 15 min. (C) Temperature rising and cooling of the ZCCN when the irradiation is on/off. (D) UV-vis results of the CCN, ZCCN and ZnO. Bandgap calculated from UV-vis spectra of (E) ZnO, (F) CCN and (G) ZCCN. (H) PL spectra investigated with 325 nm excitation wavelength of ZnO, CN and ZCCN from 400 to 700 nm. (I) ESR spectra of ZCCN after visible light irradiation for 15 min. (J) Illustration of photoresponsivity performance process in ZCCN under visible light.

Fig. 4. Spread plate results of (A) S. aureus and (B) E. coli grown on different samples; Antibacterial activity of different samples against (C) S. aureus and (D) E. coli; Surface morphologies of (E) S. aureus, and (F) E. coli treated with different groups with or without 15 min visible light irradiation, scale bars: 1 μm. Error bars indicate means ± standard deviations: **p < 0.01, and ***p < 0.001.

Fig. 5. Spread plate results of (A) S. aureus and (B) E. coli grown on different samples without light irradiation for 24 h. Antibacterial ratio of different samples against (C) S. aureus and (D) E. coli via agar plating method. TEM images and corresponding EDS analysis of intracellular sections of (E) S. aureus and (F) E. coli cultured with different samples. Scale bars are 200 nm. Error bars indicate means ± standard deviations: *p < 0.05, **p < 0.01 and ***p < 0.001.

Fig. 6. (A) Cell viability of NIH3T3 treated with all samples at day 1, 3, and 7. (B) Cell viability of NIH3T3 treated with all samples after 15 min mixed light irradiation at day 1. Gene expression measured by qRT-PCR of the angiogenic genes (C) MMP-2, (D) COL I, and (E) COL III for fibroblasts incubated for 2 and 5 days in media containing different samples. The error bars indicate means ± standard deviations: *p < 0.05, **p < 0.01, and***p < 0.001.

Fig. 7. in vivo assessment of the ZCCN with antibacterial effects and wound healing capability. (A) Photographs of the S. aureus-infected wounds treated with different dressings at time points of 0, 2, 6 and 12 days. Scale bars, 2 mm. (B) Corresponding wound area at the different time points. (C) Giemsa stained images showing the degree of infection in the wound area after a 2-day treatment. Scale bars are 50 μm. (D) Inflammatory cell ratios calculated from H&E staining data. Inflammatory cell ratios = [(total area of lymphocyte, monocytes, and neutrophil)/area of tissue] × 100 %. (E) H&E stained images showing the degree of infection of the skin tissue after 2 and 12 days. Scale bars are 50 μm. The error bars indicate means ± standard deviations: *p < 0.05, **p < 0.01.