Cytotoxicity of gold-nanorods to human HEp-2 and canine MDCK cells

Despite great potentials in biomedical sensing, imaging and therapy, the cytotoxicity of gold nanorods (GNRs) remains to be controversial. Here we address this issue via studying the cytotoxicity of gold GNRs of different aspect ratios to two types of cells: human tumor HEp-2 cells and canine MDCK cells of 'normal epithelium'. It is found that all types of GNRs displayed minimal cytotoxicity at ∼10-12 M to both cell-lines in MTT assays. However, cytotoxicity increased accordingly when dosages increased and HEp-2 cells were in general more susceptible than MDCK cells to GNRs. Time-lapse study revealed that majority cell death occurred within one hour. In contrast, free CTAB causes cell death in a time- and dose-dependent manner. This suggests that the cytotoxicity of GNRs arises from their intrinsic property rather than from free CTAB. Finally, GNRs induce apoptosis, the programmed death, which may be exploited further for tumor treatments.