Department of Pharmaceutical Sciences, University of Connecticut, 69 N Eagleville Rd U3092, Storrs, Connecticut 06269, USA.
Pharm Res. 2012 Jul;29(7):1919-31. doi: 10.1007/s11095-012-0720-x. Epub 2012 Mar 9.
To encapsulate a large amount of protein (superoxide dismutase, SOD) into unilamellar liposomes using a simple process and to investigate the lipid-protein interaction.
To achieve protein encapsulation, preformed unilamellar empty liposomes were mixed with SOD and subjected to freeze-thaw cycling. To investigate the lipid-protein interaction, a novel light scattering technique was used.
Up to 50% protein encapsulation was achieved at ∼150 nm. There was no significant change in particle size following the freeze-thaw cycling. SOD had a strong interaction with DPPC liposomes containing high concentration of cholesterol. Light scattering data revealed that in some cases the SOD molecules were present inside the lipid bilayer.
The method reported here allows great flexibility in the manufacturing process as the liposome preparation and protein-loading operations can be separated. Accordingly, empty liposomes can be prepared without concern about protein stability, making the manufacturing process more flexible and easy to control and ultimately leading to improved product quality. To explain the SOD-lipid interaction, a "pocket-embedding" theory was proposed. The encapsulation method reported here can be applied to hydrophilic small molecules as well as most hydrophilic proteins to achieve high encapsulation efficiency.
使用简单的方法将大量蛋白质（超氧化物歧化酶，SOD）包裹在单层脂质体中，并研究脂质-蛋白质相互作用。
为了实现蛋白质包封，将预先形成的单层空脂质体与 SOD 混合，并进行冻融循环。为了研究脂质-蛋白质相互作用，采用了一种新的光散射技术。
在约 150nm 时，实现了高达 50%的蛋白质包封率。冻融循环后，粒径没有明显变化。SOD 与含有高浓度胆固醇的 DPPC 脂质体有很强的相互作用。光散射数据表明，在某些情况下，SOD 分子存在于脂质双层内。
这里报道的方法在制造过程中具有很大的灵活性，因为脂质体的制备和加载操作可以分开。因此，可以在不考虑蛋白质稳定性的情况下制备空脂质体，使制造过程更加灵活和易于控制，并最终提高产品质量。为了解释 SOD-脂质相互作用，提出了“口袋嵌入”理论。这里报道的包封方法可应用于亲水性小分子以及大多数亲水性蛋白质，以实现高包封效率。
