Table 1: In vitro QDs genotoxicity studies.
| Citations (references) | Quantum dot types and sizes | Concentration/Exposure time | In vitro systems | Toxicity/Genotoxiciy assays | Findings |
| Aye, et al. μ [50] | CdSe/ZnS core-shell QDs encapsulated by fusogenic lipid (1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)) and functionalized by a nucleolipid N-μ5'-(2',3'-di-oleoyl) uridine]-N',N',N'-trimethyl ammonium tosylate (DOTAU) CdSe/ZnS-DOPC/DOTAU | In vitro Chinese hamster ovary cell line (CHO-K1 cells) | WST-1 assay Comet assay Micronucleus assay (MN) |
Protective effect of l-ergothioneine (ERT) on genotoxicity of QDs was studied in Comet assay. In dark and light conditions QDs showed genotoxic effects in the Comet assay This QDs induced MN frequencies in MN assay (in dark conditions) |
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| Aye, et al. μ [50] | CdSe/ZnS-DOPC/DOTAU | .In vitro Salmonella typhimurium tester strains A97a, TA98, TA100 and TA102 were used | Salmonella/Microsome assay | Non-mutagenic in all experimental strains both light and dark conditions | |
| Ju, et al. [13] | CdSe/ZnS QDs coated with PEG and uncoated CdSe/ZnS QDs | 8-80 nM | In vitroHuman skin fibroblasts (HSF-42) | Neutral Comet assay γH2AX foci assayIntracellular (ROS) measurement with using 2',7'-dichlorofluorescin diacetate (DCFH-DA) assay | Uncoated QDs caused significant DNA damage in a time and dose dependent manner both the neutral Comet assay and γH2AX foci formation but PEG coated QDs decreased DNA damage |
| Pathakoti, et al. μ [52] | 1) CdSe/ZnS plus amphiphilic polymer coating with COOH on the surface. 2) CdSe/ZnS plus amphiphilic polymer coating and PEG coating with-NH2 on the surface. 3) CdSe/ZnS plus amphiphilic polymer and PEI (polyethilenimine) coating with primary, secondary and tertiary amine on the surface (for 3 types of them with 530, 580 and 620 nm wavelength) |
Exposure to the various concentrations of QDs for 24 hrs for comet assay (0.2, 1, 5 and 10 nm/L) ROS mesurements (5,10, and 20 nm/L) and MTT | In vitro Human adult low calcium high temperature (HaCaT) cells |
MTT comet assay Intracellular (ROS) measurement with using 2',7'-dichlorofluorescin diacetate (DCFH-DA) assay | The QDs toxicity can be attributed to the PEI surface coating which was highly toxic to cells in comparison with PEG and significant DNA damage occurred in the HaCaT cells after exposure to QEI QDs |
| Munari, et al. μ [53] | CdS QDs and silver sulphide (Ag2S) coated with methyl polyethylene glycol (M-PEG). | 0.01-1 μg/mL concentrations for 24 and 48 hrs exposure | In vitro rainbow trout cell line (RTG-2) |
LDH, trypan blue Comet assay |
Genotoxicity CdS QD showed significant genotoxicity with a concentration response trend in the sub-toxic concentration range (0.01-1 μg/ml) after 24 hrs. No genotoxicity was observed in CdS QDs exposed RTG-2 cells after 48 hrs. |
| Katsumiti, et al. μ [56] | CdS QDs (about 5 nm) Bulk and ionic form of CdS | 0.001-100 mg Cd/L | In vitro Mytilus galloprovincialis Mussel gill cells and hemocytes |
MTT (Thiazolyl blue tetrazolium bromide) NT (Neutral Red) Comet assay |
All forms of CdS (QD, bulk and ionic) caused DNA damage and ROS production |
| Nagy, et al. μ [49] | CdSe QDs coated with mercaptopropionic acid (MPA) CdSe QDs coated with cysteamine (CYST) 3 nm |
Negatively charge MPA-QDs 20 and 160 μg/mL (non-cytotoxic concentration for Comet assay) Positively charge CYST-QDs 0.5 and 20 μg/mL (non-cytotoxic concentration for Comet assay) for 24 hrs exposure | In vitro primary normal human bronchial epithelial cells |
Comet assay DNA damage verify by presence of nuclear foci as a result of increased expression of 53 BP1 |
CYST-CdSe QDs induced DNA strand breakage with cytotoxicity, MPA-CdSe QDs induced DNA strand breakage with no cytotoxicity and ROS (Reactive Oxygen Species) production |
| Manshian, et al. μ [64] | CdSe/ZnS core/shell with amine and carboxyl-functional ligands attached to the surface (core and shell diameter average was 4-10 nm) | 0, 2.5, 5, 7.5, 10, 15 and 20 nM dispersions of QDs for 1 or 3 cell cycles. | In vitro Human bronchial epithelial cells (BEAS-2B), Human foreskin fibroblast (HFF1) Human lymphoblastoid-B (TK6) |
Cytokinesis-blocked micronucleus (CBMN) assay | Carboxyl functionalised QDs induced micronuclei frequencies both HFF1 and TK6 cell lines for 1 cell cycle period but only in TK6 cells induced MN for 3 cell cycle period. Further while amine functionalised QDs induced MN by concentration in HFF1 cells up to 10 nM but no MN induction was determined both QDs type in BEAS-2B cells |
| Wang, et al. μ [88] | CdTe QDs | 1, 10, and 50 μg /mL exposed for 12 hrs treatment | γH2AX foci | DNA damage observed but presence of an antioxidant molecule N-acetyl-cysteine (NAC) DNA damage was decreased | |
| Tang, et al. μ [90] | CdSe coated with mercaptoacetic acid-MAA | 0.043, 0.13, 0.4, 1.2, and 3.6 μmol/L for 2 hrs | In vitro Plasmid pUC18 DNA | plasmid transformation assay | Dose-dependent DNA damage was observed according to investigators' opinion Cd-MAA complex in the solution of MAA-QDs may interact with DNA through the groove-binding mode and also Cd-MAA complex has an innate tendency to damage plasmids with a high AT content or an AT-rich region |