title: Combing DNA on CTAB-coated surfaces.
abstract: A fluorescence microscope (FM) coupled with an intensified charge-coupled device (ICCD) camera was used to investigate the combing of DNA on cetyltrimethyl ammonium bromide (CTAB)-coated glass surfaces. DNA molecules can be combed uniform and straight on CTAB-coated surfaces. Different combing characteristics at different pH values were found. At lower pH (ca. 5.5), DNA molecules were stretched 30% longer than the unextended and DNA extremities bound with CTAB-coated surfaces via hydrophobic interaction. At high pH values (e.g., 6.4 and 6.5), DNA molecules were extended about 10% longer and DNA extremities bound with CTAB-coated surfaces via electrostatic attraction. At pH 6.0, DNA molecules could be extended 30% longer on 0.2-mM CTAB-coated surfaces. CTAB cationic surfactant has both a hydrophobic motif and a positively charged group. So, CTAB-coated surfaces can bind DNA extremities via hydrophobic effect or electrostatic attraction at different pH values. It was also found that combing of DNA on CTAB-coated surfaces is reversible. The number of DNA base pairs binding to CTAB-coated surfaces was calculated.
authors.affiliation: College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P.R. China.
authors.forename: Hu-Zhi
authors.initials: HZ
authors.lastname: Zheng
authors.forename: Dai-Wen
authors.initials: DW
authors.lastname: Pang
authors.forename: Zhe-Xue
authors.initials: ZX
authors.lastname: Lu
authors.forename: Zhi-Ling
authors.initials: ZL
authors.lastname: Zhang
authors.forename: Zhi-Xiong
authors.initials: ZX
authors.lastname: Xie
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics*; D001665:Binding Sites; D002412:Cations / Q000737:chemistry / Q000378:metabolism; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry / Q000378:metabolism*; D004247:DNA / Q000737:chemistry* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008856:Microscopy, Fluorescence; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry / Q000378:metabolism*
chemical_list: D002412:Cations; D002593:Cetrimonium Compounds; D013501:Surface-Active Agents; D004247:DNA; D000077286:Cetrimonium