Fig 1.
Schematic illustration for the preparation of GQDs.
Fig 2.
(a) TEM image of GQDs, (b) high-resolution TEM image of an individual GQD, (c) the size distribution of GQDs, (d) AFM image of GQDs and (e) the height profile along the lines in (d).
Fig 3.
(a) XPS survey spectra and (b) well-fitted C 1s XPS spectra and (c) well-fitted N 1s XPS spectra of GQDs (d) FTIR spectra of GQDs.
Fig 4.
a) UV-vis and PL spectra of the GQDs dispersed in water. Inset is the photographs of the GQDs aqueous solution under visible light and 365 nm UV lamp, respectively b) The fluorescence spectra of GQDs in aqueous solutions at different pH values. The spectra are measured in PBS solutions and the excitation wavelength used is 400 nm.
Fig 5.
Fluorescence images of Hela cells: (a) control cells, (b) and (c) cells treated with 50 μg/mL of GQDs for 24 h at magnification of 10 and 20 times respectively.
Fig 6.
a) Cell viability, b) LDH release and c) internal cellular ROS level of Hela cells incubated with various concentrations of GQDs for 24 h.
Data are presented as mean ± SD (n = 5 per group). (*≤ 0.05 between test and the control concentrations.)
Fig 7.
FACS results of the Annexin V-FITC and PI assay.
Scatter diagrams of cells exposed to different concentrations of GQDs for 24 h.
Fig 8.
Confocal fluorescence images of histopathological slices in heart region at excitation of 405 laser beams and heart rate of zebrafish:
a) control, b) larvae treated with 100 μg/mL, c) larvae treated with 200 μg/mL. d) heart rate of zebrafish embryos exposed to QGDs at 48, 72, 96 and 120 hpf. * denotes P < 0.05 compared with control. Values represent the mean ± SE.