Compaction Process of Calf Thymus DNA by Mixed Cationic-Zwitterionic Liposomes: A Physicochemical Study
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- 作者：Alberto Rodrí ; guez-Pulido ; Emilio Aicart ; Oscar Llorca ; Elena Junquera
- 刊名：Journal of Physical Chemistry B
- 出版年：2008
- 出版时间：February 21, 2008
- 年：2008
- 卷：112
- 期：7
- 页码：2187 - 2197
- 全文大小：696K
- 年卷期：v.112,no.7(February 21, 2008)
- ISSN：1520-5207
文摘
The compaction of calf thymus DNA (CT-DNA) by cationic liposomes constituted by a 1:1 mixture of acationic lipid, 1,2-distearoyl-3-(trimethylammonio)propane chloride (DSTAP), and a zwitterionic lipid, 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE, null net charge at pH = 7.4), has been evaluated inaqueous buffered solution at 298.15 K by means of conductometry, electrophoretic mobility, cryo-TEM, andfluorescence spectroscopy techniques. The results reveal that DSTAP/DOPE liposomes are mostly sphericaland unilamelar, with a mean diameter of around 77 ± 20 nm and a positively charged surface with a chargedensity of 
= (21 ± 1) × 10-3 C m-2. When CT-DNA is present, the genosomes DSTAP/DOPE/CT-DNA,formed by means of a surface electrostatic interaction, are generally smaller than the liposomes. Furthermore,they show a tendency to fuse forming cluster-type structures when approaching isoneutrality, which has beendetermined by the electrochemical methods at around (L/D)
= 5.6. The analysis of the decrease on thefluorescence emission of the fluorophore ethidium bromide, EtBr, initially intercalated between DNA basepairs, as long as the genosomes are formed has permitted us to confirm the electrostatic character of theDNA-liposome interaction.
= (21 ± 1) × 10-3 C m-2. When CT-DNA is present, the genosomes DSTAP/DOPE/CT-DNA,formed by means of a surface electrostatic interaction, are generally smaller than the liposomes. Furthermore,they show a tendency to fuse forming cluster-type structures when approaching isoneutrality, which has beendetermined by the electrochemical methods at around (L/D) = 5.6. The analysis of the decrease on thefluorescence emission of the fluorophore ethidium bromide, EtBr, initially intercalated between DNA basepairs, as long as the genosomes are formed has permitted us to confirm the electrostatic character of theDNA-liposome interaction.