Although silver and titanium dioxide nanoparticles (Ag NP and TiO2 NP) belong to the NP most often studied, the mechanisms of their biological effects are still not fully understood. Moreover, there are numerous discrepancies in the reports on the extent of DNA damage induced by Ag NP in various mammalian cells in in vitro studies. The available data on Ag NP genotoxicity in vitro are based on short-term assays, such as MTT or Neutral Red assay, and no attempt has been made to directly relate DNA damage to clonogenicity loss. Therefore, we undertook a detailed study of unfunctionalised Ag NP and TiO2 NP action on 3 mammalian cell lines: human hepatocellular liver carcinoma HepG2, human lung carcinoma A549 and human colorectal adenocarcinoma HT-29. The end-points examined in this report after 2h and 24h treatment with NP, were DNA breakage estimated by the comet assay and oxidative base damage recognized by formamido-pyrimidine glycosylase (FPG) and estimated with the FPG+comet assay. Further, the frequencies of histone γH2AX foci and micronuclei, apoptosis as well as metabolic activity (MTT assay) and clonogenic capacity were estimated. Each cell line had a different pattern of DNA breakage and base damage versus NP concentration and time of treatment. There were no increases in the frequencies of histone γH2AX foci and micronuclei as compared to those in the untreated cells. Our results provided no data that would link DNA damage induced by Ag NP to the early apoptosis or to the loss of clonogenic ability. Such a conclusion is especially convincing for 20 nm TiO2 NP which induce DNA damage at a level comparable to that of 20 nm Ag NP but, in contrast with 20 nm Ag NP, hardly affects clonogenic ability. This does not mean that DNA lesions induced by NP are harmless, especially at the organismal level. When incorrectly repaired, they may lead to mutations in proteins, in consequence bringing about various adverse effects on human health, including cancer predisposition, neurodegeneration, and immunodeficiency.

Sylwia Męczyńska-Wielgosz, Teresa Bartłomiejczyk, Iwona Grądzka, Anna Lankoff, Maria Wojewódzka, Grzegorz Wójciuk, Karolina Wójciuk, Maria Dusinska, Lucyna Kapka-Skrzypczak, Marcin Kruszewski



Article metrics loading...

Loading full text...

Full text loading...

  • Received: 16 May 2012
  • Accepted: 16 May 2012
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error