Incorporation of low molecular weight poly-ethylene glycol (PEG) - grafted phospholipids in vesicle bilayers is known to increase the circulation time of liposomal drug delivery vehicles. Mechanical properties of giant unilamellar DPPC vesicles containing varying concentrations of DSPE-PEG (PEG MW: 550, 1000 and 2000) were measured by micropipette aspiration assay or osmotic swelling. While the area compressibility modulus did not change significantly, the bending modulus and water permeability of the bilayer was found to increase with increasing mole fraction of DSPE-PEG. This increase was more pronounced for higher molecular weight PEG. The measured bending modulus agreed with that predicted by scaling theory only at low mole fractions of DSPE-PEG. The water permeability was also measured as a function of the increase in area per lipid (due to steric repulsion between PEG chains), and for the same area per lipid, the PEG chain with MW 550 provided a greater resistance to water transport across the vesicle membrane compared to PEG 1000 and 2000. Lysis tension of the membrane, determined by osmotic lysis method at different loading rates showed a decrease in membrane strength on inclusion of the polymer lipid. These results suggest that liposome lifetime in the circulation and the rate of drug delivery are affected by the molecular weight and concentration of PEG in the bilayer.

已知在小泡双层中掺入低分子量聚乙二醇（PEG）-接枝的磷脂会增加脂质体药物递送载体的循环时间。通过微量移液管抽吸测定或渗透溶胀来测量包含不同浓度的DSPE-PEG（PEG MW：550、1000和2000）的单层巨型DPPC囊泡的机械性能。尽管面积压缩模量没有显着变化，但是发现双层的弯曲模量和透水性随着DSPE-PEG的摩尔分数的增加而增加。对于较高分子量的PEG，这种增加更为明显。仅在DSPE-PEG的摩尔分数较低时，测得的弯曲模量与通过定标理论预测的弯曲模量一致。还测量了水渗透性作为每个脂质面积增加的函数（由于PEG链之间的空间排斥），并且对于每个脂质相同的面积，MW 550的PEG链对水在整个囊泡中的传输具有更大的抵抗力与PEG 1000和2000相比，膜的溶解张力。通过渗透裂解法在不同的加载速率下测定的膜的溶解张力显示了在包含聚合物脂质时膜强度的降低。这些结果表明，脂质体在循环中的寿命和药物递送速率受双层中PEG的分子量和浓度影响。通过渗透裂解法在不同的加载速率下测定的膜的裂解张力显示了在包含聚合物脂质时膜强度的降低。这些结果表明，脂质体在循环中的寿命和药物递送速率受双层中PEG的分子量和浓度影响。通过渗透裂解法在不同的加载速率下测定的膜的裂解张力显示了在包含聚合物脂质时膜强度的降低。这些结果表明，脂质体在循环中的寿命和药物递送速率受双层中PEG的分子量和浓度影响。