Structure of the Complex Monolayer of Gemini Surfactant and DNA at the Air/Water Interface
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- 作者：Qibin Chen ; Xueli Kang ; Rong Li ; Xuezhong Du ; Yazhuo Shang ; Honglai Liu ; Ying Hu
- 刊名：Langmuir
- 出版年：2012
- 出版时间：February 21, 2012
- 年：2012
- 卷：28
- 期：7
- 页码：3429-3438
- 全文大小：542K
- 年卷期：v.28,no.7(February 21, 2012)
- ISSN：1520-5827
文摘
The properties of the complex monolayers composed of cationic gemini surfactants, [C18H37(CH3)2N+-(CH2)s-N+(CH3)2C18H37],2Br鈥?/sup> (18-s-18 with s = 3, 4, 6, 8, 10 and 12), and ds-DNA or ss-DNA at the air/water interface were in situ studied by the surface pressure鈥揳rea per molecule (蟺鈥?i>A) isotherm measurement and the infrared reflection absorption spectroscopy (IRRAS). The corresponding Langmuir鈥揃lodgett (LB) films were also investigated by the atomic force microscopy (AFM), the Fourier transform infrared spectroscopy (FT-IR), and the circular dichroism spectroscopy (CD). The 蟺鈥?i>A isotherms and AFM images reveal that the spacer of gemini surfactant has a significant effect on the surface properties of the complex monolayers. As s 鈮?6, the gemini/ds-DNA complex monolayers can both laterally and normally aggregate to form fibril structures with heights of 2.0鈥?.0 nm and widths of from several tens to 300 nm. As s > 6, they can laterally condense to form the platform structure with about 1.4 nm height. Nevertheless, FT-IR, IRRAS, and CD spectra, as well as AFM images, suggest that DNA retains its double-stranded character when complexed. This is very important and meaningful for gene therapy because it is crucial to maintain the extracellular genes undamaged to obtain a high transfection efficiency. In addition, when s 鈮?6, the gemini/ds-DNA complex monolayers can experience a transition of DNA molecule from the double-stranded helical structure to a typical 蠄-phase with a supramolecular chiral order.