The difference between the LDH inactivation potentials of Ag-40 and Ag-35 (Figure 2) could be caused by the presence of carbon matrix that is used for preventing aggregation of Ag-35 NPs during synthesizing process while Ag-40 NPs do not contain carbon matrix. This finding, together with some studies on NP-protein interactions (Cedervall et al., 2007; Linse et al., 2007), suggest that carbon-based or carbon-containing
In summary, among the several NPs examined, Cu-40 and Ag-35 NPs were able to inactivate LDH. Therefore, data from LDH assay have to be interpreted with caution whenever the assay is used for assessing cytotoxicity of an ROS-generating material. This result also confirmed the importance of combining several cytotoxicity assays when evaluating a chemical or NP.