In Vitro Toxicity of Silver Nanoparticles at Noncytotoxic Doses to HepG2 Human Hepatoma Cells

• Published in: Environmental science & technology Vol. 43; no. 15; pp. 6046 - 6051
• Main Authors: Kawata, Koji, Osawa, Masato, Okabe, Satoshi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.08.2009
• Subjects: Animal, plant and microbial ecology; Applied ecology; Applied sciences; Biological and medical sciences; Cell cycle; Cell Line, Tumor; Cells; Comparative analysis; Cysteine - chemistry; Deoxyribonucleic acid; DNA; DNA Damage; Drug Screening Assays, Antitumor - methods; Ecotoxicology and Human Environmental Health; Ecotoxicology, biological effects of pollution; Effects; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Profiling; Gene Expression Regulation, Neoplastic - drug effects; Humans; Ions; Kinases; Metal Nanoparticles - chemistry; Metal Nanoparticles - toxicity; Micronucleus Tests - methods; Nanoparticles; Nanotechnology - methods; Oligonucleotide Array Sequence Analysis; Oxidative Stress; Pollution; Reactive Oxygen Species; Silver; Silver - chemistry; Silver - toxicity; Toxicity; Human; Silver; Nanoparticle; Toxicity; In vitro; Nanostructured materials
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es900754q

Although it has been reported that silver nanoparticles (Ag-NPs) have strong acute toxic effects to various cultured cells, the toxic effects at noncytotoxic doses are still unknown. We, therefore, evaluated in vitro toxicity of Ag-NPs at noncytotoxic doses in human hepatoma cell line, HepG2, based on cell viability assay, micronucleus test, and DNA microarray analysis. We also used polystyrene nanoparticles (PS-NPs) and silver carbonate (Ag2CO3) as test materials to compare the toxic effects with respect to different raw chemical composition and form of silver. The cell viability assay demonstrated that Ag-NPs accelerated cell proliferation at low doses (<0.5 mg/L), which was supported by the DNA microarray analysis showing significant induction of genes associated with cell cycle progression. However, only Ag-NPs exposure exhibited a significant cytotoxicity at higher doses (>1.0 mg/L) and induced abnormal cellular morphology, displaying cellular shrinkage and acquisition of an irregular shape. In addition, only Ag-NPs exposure increased the frequency of micronucleus formation up to 47.9 ± 3.2% of binucleated cells, suggesting that Ag-NPs appear to cause much stronger damages to chromosome than PS-NPs and ionic Ag+. Cysteine, a strong ionic Ag+ ligand, only partially abolished the formation of micronuclei mediated by Ag-NPs and changed the gene expression, indicating that ionic Ag+ derived from Ag-NPs could not fully explain these biological actions. Based on these discussions, it is concluded that both “nanosized particle of Ag” as well as “ionic Ag+” contribute to the toxic effects of Ag-NPs.