Impact of nanosilver on various DNA lesions and HPRT gene mutations – effects of charge and surface coating

Abstract

BackgroundThe main goal of this research was to study the interactions of a fully characterized set of silver nanomaterials (Ag ENMs) with cells in vitro, according to the standards of Good Laboratory Practices (GLP), to assure the quality of nanotoxicology research. We were interested in whether Ag ENMs synthesized by the same method, with the same size distribution, shape and specific surface area, but with different charges and surface compositions could give different biological responses.MethodsA range of methods and toxicity endpoints were applied to study the impacts of interaction of the Ag ENMs with TK6 cells. As tests of viability, relative growth activity and trypan blue exclusion were applied. Genotoxicity was evaluated by the alkaline comet assay for detection of strand breaks and oxidized purines. The mutagenic potential of Ag ENMs was investigated with the in vitro HPRT gene mutation test on V79-4 cells according to the OECD protocol. Ag ENM agglomeration, dissolution as well as uptake and distribution within the cells were investigated as crucial aspects of Ag ENM toxicity. Ag ENM stabilizers were included in addition to positive and negative controls.ResultsDifferent cytotoxic effects were observed including membrane damage, cell cycle arrest and cell death. Ag ENMs also induced various kinds of DNA damage including strand breaks and DNA oxidation, and caused gene mutation. We found that positive Ag ENMs had greater impact on cyto- and genotoxicity than did Ag ENMs with neutral or negative charge, assumed to be related to their greater uptake into cells and to their presence in the nucleus and mitochondria, implying that Ag ENMs might induce toxicity by both direct and indirect mechanisms.ConclusionWe showed that Ag ENMs could be cytotoxic, genotoxic and mutagenic. Our experiments with the HPRT gene mutation assay demonstrated that surface chemical composition plays a significant role in Ag ENM toxicity.

Impact of storage conditions and storage time on silver nanoparticles' physicochemical properties and implications for their biological effects

“…They caused a decrease in the number of cells (Ag_SDS) and, which is most striking, acidication and swelling of lysosomes (T6:RT-DL samples), which presumably precedes lysosomal membrane rupture. 31 Thus, Ag_SDS NPs' ability to induce cytotoxicity, measured as a decrease in the cell number (HCS, PE) increased with aging, regardless of the storage conditions, and may be caused by Ag dissolution resulting in increasing concentrations of free SDS. 5), suggests that the increased concentration of Ag + exerts the nal Ag_SDS (PE) and Ag_Citrate (HCS) toxicity, which is consistent with previous reports.…”

“…30,31 Six different stabilizers were utilized: two negatively charged: 3-sodium citrate (Na 3 C 6 H 5 O 7 ; Fisher Scientic, Schwerte, Germany) and sodium dodecyl sulfate (SDS; Sigma-Aldrich, St. Louis, MO, USA); two positively charged: chitosan (high molecular weight; Sigma-Aldrich, Tauirchen, Germany) and BYK-9076® (BYK-Chemie, Wesel, Germany); and two neutral: Tween 80® (Sigma-Aldrich, Tauirchen, Germany) and DISPERBYK-192® (BYK-Chemie, Wesel, Germany). Silver nitrate (AgNO 3 ; Heraeus, Hanau, Germany) was used as the metal precursor and sodium borohydride (NaBH 4 ; ACROS Organics, Geel, Belgium) as the reducing agent (modied protocol of Creighton et al).…”

Immunotoxicity, genotoxicity and epigenetic toxicity of nanomaterials: New strategies for toxicity testing?

“…Mutations are assessed at a specific locus -often the HPRT (hypoxanthine phosphoribosyltransferase) or TK (thymidine kinase) genes (Wang et al, 2007;Huk et al, 2014Huk et al, , 2015Gabelova et al, 2017). These assays can detect a range of mutations, including deletions; however, the mouse lymphoma assay (based on the TK gene) detects deletions with higher efficiency compared with the HPRT gene mutation test (Johnson, 2012).…”

Cytotoxic and Antiproliferative Effects of Nanomaterials on Cancer Cell Lines: A Review

“…Assessing antitumor properties of NPs requires stability in investigation under in vitro cell culture conditions. The interactions between NPs and biomolecules present in the culture media, such as proteins and lipids, could change nanomaterial's characteristics [12]. For instance, research has demonstrated the formation of protein corona around NP surface due to interaction with cellular media, resulting in modifications of their physical properties and leading, for instance, to aggregation and sedimentation [13].…”

“…It is important to note that AgNPs_byk formed the smallest agglomerates in medium solution in comparison to other coated AgNPs, suggesting that size is an important factor in toxicity. To sum up, coated NPs display various biological in vitro effects depending mainly on their surface charge [12].…”