An In Vitro Study on the Cytotoxicity and Genotoxicity of Silver Sulfide Quantum Dots Coated with Meso-2,3-dimercaptosuccinic Acid.

OBJECTIVES: Silver sulfide (Ag2S) quantum dots (QDs) are highly promising nanomaterials in bioimaging systems due to their high activities for both imaging and drug/gene delivery. There is insufficient research on the toxicity of Ag2S QDs coated with meso-2,3-dimercaptosuccinic acid (DMSA). In this study, we aimed to determine the cytotoxicity of Ag2S QDs coated with DMSA in Chinese hamster lung fibroblast (V79) cells over a wide range of concentrations (5-2000 µg/mL). MATERIALS AND METHODS: Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and neutral red uptake (NRU) assays. The genotoxic and apoptotic effects of DMSA/Ag2S QDs were also assessed by comet assay and real-time polymerase chain reaction technique, respectively. RESULTS: Cell viability was 54.0±4.8% and 65.7±4.1% at the highest dose (2000 µg/mL) of Ag2S QDs using the MTT and NRU assays, respectively. Although cell viability decreased above 400 µg/mL (MTT assay) and 800 µg/mL (NRU assay), DNA damage was not induced by DMSA/Ag2S QDs at the studied concentrations. The mRNA expression levels of p53, caspase-3, caspase-9, Bax, Bcl-2, and survivin genes were altered in the cells exposed to 500 and 1000 µg/mL DMSA/Ag2S QDs. CONCLUSION: The cytotoxic effects of DMSA/Ag2S QDs may occur at high doses through the apoptotic pathways. However, DMSA/Ag2S QDs appear to be biocompatible at low doses, making them well suited for cell labeling applications.

Effects of silver sulfide quantum dots coated with 2-mercaptopropionic acid on genotoxic and apoptotic pathways in vitro.

Quantum dots (QDs) are highly promising nanomaterials in bioimaging system because of their bright fluorescence, broad UV excitation, narrow emission band, and high photostability. Recently, there is a great activity on Ag2S quantum dots for both imaging and drug/gene delivery due to the potential of having a better cytocompatability and near infrared luminescence. 2-Mercaptopropionic acid (2 MP A)-coated silver sulfide (Ag2S) QDs were reported as the most luminescent, stable, anionic Ag2S QDs in the literature. In this study, we aim to determine the cytotoxicity of 2 MP A/Ag2S in Chinese hamster lung fibroblast (V79) cells. The genotoxic and apoptotic effects of 2 MP A/Ag2S QDs were assessed by the alkaline single cell electrophoresis assay and real time polymerase chain reaction techniques, respectively. The cell viability decreased above 200 µg/ml and 800 µg/ml for MTT tetrazolium and neural red uptake assays, respectively. DNA damage was not observed by 2 MP A/Ag2S QDs at the studied concentration levels (5-2000 µg/ml). The levels of mRNA expression of p53, caspase 3, caspase 9, bax, bcl-2, survivin were not changed by 2 MP A/Ag2S QDs below IC50 (around 1000 µg/ml). Hence, 2 MP A/Ag2S QDs did not show any cytotoxic or genotoxic effects in V79 cells at lower doses. We conclude that the biocompatibility of 2 MP A/Ag2SODs makes them suitable for cell labeling applications.

Use of in vitro assays to assess the potential cytotoxic, genotoxic and antigenotoxic effects of vanillic and cinnamic acid.

Vanillic acid (VA) found in vanilla and cinnamic acid (CA) the precursor of flavonoids and found in cinnamon oil, are natural plant phenolic acids which are secondary aromatic plant products suggested to possess many physiological and pharmacological functions. In vitro and in vivo experiments have shown that phenolic acids exhibit powerful effects on biological responses by scavenging free radicals and eliciting antioxidant capacity. In the present study, we investigated the antioxidant capacity of VA and CA by the trolox equivalent antioxidant capacity (TEAC) assay, cytotoxicity by neutral red uptake (NRU) assay in Chinese Hamster Ovary (CHO) cells and also the genotoxic and antigenotoxic effects of these phenolic acids using the cytokinesis-blocked micronucleus (CBMN) and the alkaline comet assays in human peripheral blood lymphocytes. At all tested concentrations, VA (0.17-67.2 µg/ml) showed antioxidant activity but CA (0.15-59.2 µg/ml) did not show antioxidant activity against 2,2-azino-bis (3-ethylbenz-thiazoline-6-sulphonic acid) (ABTS). VA (0.84, 4.2, 8.4, 16.8, 84 and 168 µg/ml) and CA (0.74, 3.7, 7.4, 14.8, 74, 148 µg/ml) did not have cytotoxic and genotoxic effects alone at the studied concentrations as compared with the controls. Both VA and CA seem to decrease DNA damage induced by H2O2 in human lymphocytes.