Fig. 3: Structure and biosafety of CQDs.

a Schematic of the synthesis of CQDs. b TEM and HRTEM (top right corner inset) images of the CQDs. Bottom left corner inset: Particle size distribution chart, which contains histogram fitted to a Gaussian curve. Experiment independently repeated 3 times with similar results. c AFM images of the CQDs. Inset: height profile along the line. Experiment independently repeated 3 times with similar results. d FT-IR spectra of the CQDs and ox-CQDs. e, f Hydrogen NMR spectra of the CQDs and ox-CQDs in DMSO-d6. g Photographs of the CQD solid and solution. h PL imaging of the major mouse organs conducted at different time points before and after intravenous injection of 100 µL of CQD aqueous solution (100 µL, 1000 µg mL⁻¹). (Ex, 589 nm laser; Em, 650 nm longpass [LP] optical filter). Scale bar: 5 mm. i Live/dead cell imaging assays of 4T1 cells treated with CQDs (500 μg mL⁻¹) after 1064 nm laser irradiation (1 W cm⁻²) for 10 min. Viable cells (green) and dead cells (red) were stained with Calcein AM and propidium iodide (PI), respectively. Source data is provided as a Source Data file.