Figure 2.

(A) The insoluble purple formazan product generated in the AuNC@DHLA aqueous solution when upon X-ray radiation (6.0 Gy). Moreover, more formazan could be observed with increasing the concentration of AuNC@DHLA. In the presence of superoxide dismutase (SOD), a scavenger of O₂^-•, these insoluble formazans could not be observed. (B) The amount of O₂^-• as a function of the dosage of X-ray. Increasing the dosage of X-ray generally results in more amount of O₂^-•. Besides that, under the same X-ray radiation conditions, more AuNC@DHLA generally produce more amount of O₂^-•. Statistical analysis was performed by two-tailed t-test (**p < 0.01). (C) Generation of HO• during X-ray radiation in the presence of AuNC@DHLA was analyzed using 3′-(p-aminophenyl) fluorescein (APF) as the HO• trap. The amount of generated HO• increased with increasing the dosage of X-ray. Statistical analysis was performed by two-tailed t-test (**p < 0.01, ***p < 0.001). (D) Generation of ¹O₂ from AuNC@DHLA upon X-ray radiation was analyzed with singlet oxygen sensor green (SOSG) assay. No apparent signal of ¹O₂ could be detected. Statistical analysis was performed by two-tailed t-test (N.S. p > 0.05). (E) Images of Hepa 1-6 cells stained with 2′,7′-dichlorodihydrofluorescein diacetate (DCFH-DA) after treatment with AuNC@DHLA and X-ray (0.5 Gy). For comparison, other controls, including treatment with AuNC@DHLA (200 μg mL^-1) alone (without X-ray) and X-ray alone, are also demonstrated. The blank control group of cells received neither AuNC@DHLA nor X-ray. BF: bright field; FL: fluorescence after staining with 2′, 7′-dichlorodihydrofluorescein diacetate (DCFH-DA). (F) Corresponding intracellular fluorescence intensity of Hepa 1-6 cells (N ≥ 50). The concentration of AuNC was 200 μg mL^-1. The box plot showed data points, and one point corresponded to the intensity per cell. Statistical analysis was performed by two-tailed t-test (***p < 0.001).