title: Direct nanomaterial-DNA contact effects on DNA and mutation induction.
abstract: The toxicity of nanomaterials has been well known, but mechanisms involved have been little known. This study was aimed at looking at direct interaction between nanomaterials and naked DNA for some fundamental understanding. Two different types of nanomaterials, carbon nanotubes (CNTs) and tungsten trioxide (WO₃) nanoplates, were simply mixed with naked DNA plasmid, respectively, in two different contact modes, dry or wet (in solution), for varied time periods. DNA topological forms were analyzed for changes using gel electrophoresis and fluoro-spectrometry. The nanomaterial-contacted DNA was transferred into bacteria Escherichia coli (E. coli) cells for mutation observation. Certain types and degrees of DNA damage were observed, such as single strand break and double strand break, and bacterial mutation was confirmed. The DNA damage increased with the contacting time in an exponential manner and increased more rapidly in the initial stage for the wet contact. The nanomaterials-contacted DNA transferred bacteria had about less than 10% survival but almost 100% mutation for the surviving cells. The CNTs were more offensive than the metal oxide nanomaterials. The mutation spectrum from the DNA sequencing analysis showed that DNA point mutation was dominated by transversion, which was dominated by guanine changes in the wet contact condition while by cytosine changes in the dry contact condition. The point mutation occurrence in the wet contact was more than in the dry contact, confirming the wet contact more active and thus dangerous than dry contact. This experiment, although as a model study, revealed that direct simple contacts between nanomaterials and DNA could cause DNA changes and thus induce mutations which might potentially lead to cancers, diseases and genetic changes. This could be a mechanism for nanomaterial genotoxicity to the cells and also provided a caution to applications in using nanomaterials for DNA delivery.
authors: Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400, Thailand; Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
authors: P
authors: P
authors: Thongkumkoon
authors: Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; Biotechnology Unit, University of Phayao, Muang, Phayao 56000, Thailand.
authors: K
authors: K
authors: Sangwijit
authors: Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
authors: C
authors: C
authors: Chaiwong
authors: Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
authors: S
authors: S
authors: Thongtem
authors: Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
authors: P
authors: P
authors: Singjai
authors: Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; Thailand Center of Excellence in Physics, Commission on Higher Education, 328 Si Ayutthaya Road, Bangkok 10400, Thailand. Electronic address: yuld@thep-center.org.
authors: L D
authors: LD
authors: Yu
mesh_terms: D004247:DNA / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D004249:DNA Damage; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D053768:Metal Nanoparticles / Q000633:toxicity*; D016296:Mutagenesis; D009152:Mutagenicity Tests; D037742:Nanotubes, Carbon / Q000633:toxicity*; D009690:Nucleic Acid Conformation; D010087:Oxides / Q000633:toxicity*; D010957:Plasmids / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D017354:Point Mutation; D013997:Time Factors; D014162:Transfection; D014414:Tungsten / Q000633:toxicity*
chemical_list: D037742:Nanotubes, Carbon; D010087:Oxides; D049452:Green Fluorescent Proteins; D004247:DNA; C511604:tungsten oxide; D014414:Tungsten
keywords: Carbon nanotubes (CNTs); DNA; Escherichia coli (E. coli); Mutation; Nanomaterial; Toxicity; Tungsten trioxide (WO(3))