Figure 5: Corona-mediated sulphidation of Ag NPs impacts particle toxicity.

TEM images of partially sulphidated Ag NPs after pre-incubation in RPMI-1640 with 10% FBS (a) and completely sulphidated Ag NPs after pre-incubation in RPMI-1640 with 1% FBS (b); scale bars are 50 nm; Viability of J774 murine macrophages (as measured with MTT assays) after 24 h exposure to various concentrations (2, 5, 10, 15, 25, 50 and 100 μg ml⁻¹) of Ag⁺ ions (black diamonds), pristine Ag NPs (red triangles), partially sulphidated Ag NPs (blue squares) and completely sulphidated Ag NPs (orange circles); error bars are provided as standard deviation; statistically significant differences (two-tailed t-test, with all data sets showing normal distribution and similar variance values) as compared with the control are marked with **P<0.005 or ***P<0.0005 (n=6), with all the P values available in Supplementary Table 7 (c); release profiles of TNFα (d) and MIP-2 (e) after 24 h exposure of J774 macrophages to various concentrations (2, 5, 10, 15, 25, 50 and 100 μg ml⁻¹) of pristine (red), partially sulphidated (blue) and completely sulphidated (orange) Ag NPs; the missing concentrations of TNFα and MIP-2 after exposure to pristine Ag NPs are above the measuring limit (see calibration curves in Supplementary Fig. 29).