Complexation of DNA with cationic surfactants as studied by small-angle X-ray scattering

• Published in: Science China. Chemistry Vol. 57; no. 12; pp. 1738 - 1745
• Main Authors: Niu, Lin, Yan, JingJing, Yang, XuYan, Burger, Christian, Rong, LiXia, Hsiao, Benjamin, Liang, DeHai
• Format: Journal Article
• Language: English
• Published: Heidelberg Science China Press 01.12.2014; Springer Nature B.V
• Subjects: Cetyltrimethylammonium bromide; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Hexagonal phase; Lamella; Oligonucleotides; Small angle X ray scattering; Synchrotrons; phase behavior; synchrotron small-angle X-ray scattering; kinetics; DNA; surfactant
• ISSN: 1674-7291; 1869-1870
• DOI: 10.1007/s11426-014-5159-y

The phase behaviors of the complex formed by didodecyldimethylammonium bromide (DDAB) and cetyltrimethylammonium bromide (CTAB) interacting with three different types of DNAs, salmon testes DNA (∼2000 bp), 21-bp double-stranded oligonucleotides (oligo-dsDNA), and 21-nt single-stranded oligonucleotides (oligo-ssDNA) were studied by synchrotron small-angle X-ray scattering. It was found that the DNA length and flexibility, together with the positive/negative charge ratio, determined the final structure. At higher charge ratios, the DNA length exhibited negligible effect. Both oligo-dsDNA and salmon DNA formed inverted hexagonal packing of cylinders with CTAB, as well as bilayered lamella with DDAB. However, at lower charge ratios, oligo-dsDNA formed a distorted hexagonal phase with CTAB and a new structure with DDAB, which was different from the behaviors of salmon DNA. The flexible oligo-ssDNA formed rich structures that were subject to environmental disturbance. Kinetic study also indicated that the structures of the complex formed by oligo-ssDNA took much longer to mature than the structures formed by oligo-dsDNA. We attributed this result to the conformational adjustment of oligo-ssDNA in the complex.