title: Electron microscopic visualization of complementary labeled DNA with platinum-containing guanine derivative.
abstract: The object of the present report is to provide a method for a visualization of DNA in TEM by complementary labeling of cytosine with guanine derivative, which contains platinum as contrast-enhanced heavy element. The stretched single-chain DNA was obtained by modifying double-stranded DNA. The labeling method comprises the following steps: (i) stretching and adsorption of DNA on the support film of an electron microscope grid (the hydrophobic carbon film holding negative charged DNA); (ii) complementary labeling of the cytosine bases from the stretched single-stranded DNA pieces on the support film with platinum containing guanine derivative to form base-specific hydrogen bond; and (iii) producing a magnified image of the base-specific labeled DNA. Stretched single-stranded DNA on a support film is obtained by a rapid elongation of DNA pieces on the surface between air and aqueous buffer solution. The attached platinum-containing guanine derivative serves as a high-dense marker and it can be discriminated from the surrounding background of support carbon film and visualized by use of conventional TEM observation at 100 kV accelerated voltage. This method allows examination of specific nucleic macromolecules through atom-by-atom analysis and it is promising way toward future DNA-sequencing or molecular diagnostics of nucleic acids by electron microscopic observation.
authors.affiliation: Department of Chemistry, Graduate School of Science and Engineering, Saitama University, 255 Shimookubo, Sakura-Ku, Saitama, 338-8570, Japan.|Department of Engineering Geoecology, Laboratory of Engineering NanoBiotechnology, University of Mining and Geology "St. Ivan Rilski", Bulgaria.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Loukanov
authors.affiliation: Department of Infectious Pathology, Hygiene, Technology and Control of Food Stuffs of Animal Origin, Faculty of Veterinary Medicine, University of Forestry, Sofia, Bulgaria.
authors.forename: Chavdar
authors.initials: C
authors.lastname: Filipov
authors.affiliation: Department of Engineering Geoecology, Laboratory of Engineering NanoBiotechnology, University of Mining and Geology "St. Ivan Rilski", Bulgaria.
authors.forename: Polina
authors.initials: P
authors.lastname: Mladenova
authors.affiliation: Department of Engineering Geoecology, Laboratory of Engineering NanoBiotechnology, University of Mining and Geology "St. Ivan Rilski", Bulgaria.
authors.forename: Svetlin
authors.initials: S
authors.lastname: Toshev
authors.affiliation: Materials Research Laboratory, University of Nova Gorica, Nova Gorica, SI-5000, Slovenia.
authors.forename: Saim
authors.initials: S
authors.lastname: Emin
mesh_terms: D018076:DNA, Complementary / Q000737:chemistry* / Q000648:ultrastructure*; D006147:Guanine / Q000737:chemistry*; D008854:Microscopy, Electron; D009690:Nucleic Acid Conformation; D010984:Platinum / Q000737:chemistry*; D013194:Staining and Labeling
chemical_list: D018076:DNA, Complementary; D010984:Platinum; D006147:Guanine
keywords: DNA sequences; DNA stretching and visualization; contrast-enhanced Pt-containing guanine