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Abstract：
In this paper, the adsorption behavior of DNA on 1,2-dipalmitoyl-sn-glycero-3- phosphocholine (DPPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) mixed lipid monolayers had been studied at the air-water interface through the surface pressure-area curves (π-A), adsorption curves (π/π0-t), excess mean area (∆Aexc), excess Gibbs free energy (∆Gex) and the atomic force microscopy (AFM). π-A isotherms showed that the curves moved to larger mean molecular area after DNA added into subphase, however, the curves shifted to smaller mean molecular area when the concentration of DNA was higher than 1.2 μg/mL. The result of adsorption curves indicated that DNA molecules were spread by combining with polar head groups of lipids except the concentration of DNA was 0.4 μg/mL. ∆Aexc and ∆Gex demonstrated that DNA enlarged the interval between DPPC and POPC, and the strongest position happened at the concentration of DNA was 1.2 μg/mL. These phenomena might be the steric hindrance between DNA molecules. Morphology of surface observed by AFM was agreement with the results above, which verified our conclusion from a more intuitive aspect. This work provides useful theoretical basis for the development of novel DNA delivery materials.
摘要：
在本文中,研究了DNA在1,2-二棕榈酰-sn-甘油-3-磷酸胆碱（DPPC）和1-棕榈酰-2-油酰基-sn-甘油-3-磷酸胆碱（POPC）混合脂质单层上的吸附行为。通过表面压力-面积曲线（π-A），吸附曲线(π/π0-t)，超额平均面积(ΔAexc)，多余的吉布斯自由能(ΔGex)和原子力显微镜(AFM)。π-A等温线表明，在DNA加入亚相后，曲线移动到更大的平均分子面积，然而,当DNA浓度高于1.2μg/mL时，曲线移至较小的平均分子面积。吸附曲线的结果表明，除DNA浓度为0.4μg/mL外，DNA分子通过与脂质的极性头基结合而扩散。ΔAexc和ΔGex证明DNA扩大了DPPC和POPC之间的间隔，最强位置发生在DNA浓度为1.2μg/mL时。这些现象可能是DNA分子之间的空间位阻。通过AFM观察到的表面形态与上述结果一致。从更直观的方面验证了我们的结论。这项工作为开发新型DNA递送材料提供了有益的理论基础。
