Titration of DNA/Carbon Nanotube Complexes with Double-Chained Oppositely Charged Surfactants

Nanomaterials

Franco Tardani¹  Camillo La Mesa¹ 

关键词: single- and double strand DNA;    ss-DNA and ds-DNA;    multi-walled carbon nanotubes (MWCNTs);    1/1 ss-DNA/MWCNT complexes;    double-chained cationic surfactants;    phase diagram;   

DOI  :  10.3390/nano5020722

来源: mdpi

【 摘 要 】

1/1 dispersions of ss-DNA/CNT complexes in mass ratios were investigated in a mixture with didodecyldimethylammonium bromide, DDAB. Depending on the amounts of the surface-active agent and of the complexes, solutions, precipitates, or re-dissolution occur. DDAB titrates the phosphate groups on the outer surface of the complex and controls the phase sequence in these systems. The combination of different experimental methods determined the phases that occur therein. The results are based on optical absorbance, Dynamic Light Scattering, ionic conductivity, ζ-potential, optical microscopy and AFM. From the above findings a (pseudo)-binary phase diagram is attained. The system has strong similarities with polymer-surfactant mixtures. In fact, its properties conform to cases in which interactions between rigid rod-like polyelectrolytes and oppositely charged species take place. The peculiarities of double-chained DDAB in the process imply significant differences with respect to the behavior of single chain surfactants. In fact, DDAB associates into vesicular entities, when the homologous single chain species forms small micellar aggregates.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.