A laser Raman microscope (Thermo Fisher, USA) was used to investigate the alteration of nuclear components after uptake of AG-QDs (200 μg/mL) into this organelle for 24 and 48 h. The nuclear areas were located by light microscopy, and a laser with the excitation wavelength at 438 nm was used to focus and collect all Raman signals in the sample.
For the investigation on DNA damage, NR8383 cells were exposed to AG-QDs (0 and 200 μg/mL), H2O2 (50 μL/mL), or AG-QDs (200 μg/mL) with GSH (10 μg/mL) for 24 h at 37 °C. The DNA of NR8383 cells in each treatment was extracted using a Genomic DNA Mini Preparation Kit with a Spin Column (Beyotime Institute of Biotechnology, China) according to the manufacturer’s instructions. The extracted DNA was dissolved in DI water (20 ng/μL) and was deposited on a freshly cleaved mica substrate (1 cm × 1 cm). After washing and air-drying, the DNA chain morphology on the mica substrate was imaged by AFM in tapping mode. Moreover, the extracted DNA samples (20 ng/μL) from the un-exposed cells were mixed with AG-QDs (200 μg/mL), and then were allowed to sit for 24 h prior to morphological observation by AFM. In addition, ROS levels of AG-QDs alone and NR8383 cells after exposure to AG-QDs (200 μg/mL) were detected using 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA, Beyotime Institute of Biotechnology, China) by a fluorescence spectrophotometer.
For the investigation on DNA damage, NR8383 cells were exposed to AG-QDs (0 and 200 μg/mL), H2O2 (50 μL/mL), or AG-QDs (200 μg/mL) with GSH (10 μg/mL) for 24 h at 37 °C. The DNA of NR8383 cells in each treatment was extracted using a Genomic DNA Mini Preparation Kit with a Spin Column (Beyotime Institute of Biotechnology, China) according to the manufacturer’s instructions. The extracted DNA was dissolved in DI water (20 ng/μL) and was deposited on a freshly cleaved mica substrate (1 cm × 1 cm). After washing and air-drying, the DNA chain morphology on the mica substrate was imaged by AFM in tapping mode. Moreover, the extracted DNA samples (20 ng/μL) from the un-exposed cells were mixed with AG-QDs (200 μg/mL), and then were allowed to sit for 24 h prior to morphological observation by AFM. In addition, ROS levels of AG-QDs alone and NR8383 cells after exposure to AG-QDs (200 μg/mL) were detected using 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA, Beyotime Institute of Biotechnology, China) by a fluorescence spectrophotometer.