Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, People's Republic of China.
J Phys Chem B. 2010 Jan 28;114(3):1271-6. doi: 10.1021/jp910024n.
We have investigated the adsorption of hydrophobically end-capped poly(ethylene glycol) (HE-PEG) with carbon number (m) in the hydrocarbon end chain ranging from 0 to 16 onto phospholipid membrane by use of quartz crystal microbalance with dissipation (QCM-D), surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC). QCM-D and SPR studies show that the hydrophobic interaction between HE-PEG chains and the lipid membrane increases with the hydrocarbon chain length. At a low HE-PEG concentration, the adsorption cannot induce a vesicle-to-bilayer transition until the carbon number is up to 16. However, at a high HE-PEG concentration, the adsorption results in a vesicle-to-bilayer transition at m > or = 12. ITC measurements demonstrate that enthalpy change (DeltaH) for the mixing of lipid vesicles with HE-PEG chains is too small to be detectable when m is less than 12. However, DeltaH changes from positive to negative as the carbon number increases from 12 to 16, indicating that the HE-PEG insertion increases with its hydrocarbon end-chain length. The present study reveals that the hydrophobic interaction between the lipid membrane and HE-PEG chains as well as the osmotic pressure drive the adsorption and insertion of such polymer chains.
我们通过使用石英晶体微天平（QCM-D）、表面等离子体共振（SPR）和等温热力学滴定（ITC）研究了碳数（m）在 0 到 16 之间的疏水封端聚乙二醇（HE-PEG）在磷脂膜上的吸附。QCM-D 和 SPR 研究表明，HE-PEG 链与脂质膜之间的疏水相互作用随碳链长度的增加而增加。在低浓度的 HE-PEG 时，只有碳数达到 16 时，吸附才不能诱导囊泡到双层膜的转变。然而，在高浓度的 HE-PEG 时，吸附导致碳数大于或等于 12 时囊泡到双层膜的转变。ITC 测量表明，当 m 小于 12 时，脂质囊泡与 HE-PEG 链混合的焓变（ΔH）太小而无法检测到。然而，随着碳数从 12 增加到 16，ΔH 从正值变为负值，表明 HE-PEG 的插入随其碳氢末端链长度的增加而增加。本研究揭示了脂质膜与 HE-PEG 链之间的疏水相互作用以及渗透压驱动了这些聚合物链的吸附和插入。
