Burridge Kelley A, Figa Michael A, Wong Joyce Y
Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA.
Langmuir. 2004 Nov 9;20(23):10252-9. doi: 10.1021/la0489099.
To achieve efficient targeting, carriers containing either drugs or imaging agents must have surface properties that promote binding to targets yet at the same time block rapid immune system clearance. Here we describe a versatile technique that allows simultaneous comparison of the effects of carrier surface composition on binding properties under identical flow conditions. Parallel lanes of supported lipid bilayers that mimic the surface of liposomal delivery vehicles are formed using the vesicle fusion method in microfluidic channels created via standard soft lithography techniques. Vesicle stock solutions are premixed and injected into lanes formed by a poly(dimethylsiloxane) (PDMS) stamp reversibly sealed to a glass slide to create adjacent lanes of distinct composition. After removing the stamp, an adsorbed layer of bovine serum albumin (BSA) is used to prevent bilayer spreading before assembling the patterned substrate into a flow chamber for binding studies. Advantages of this method include easy and rapid preparation of bilayers with desired compositions from an unlimited number of lipid types, choice of feature size, time-stable features, and low nonspecific binding. Feature sizes on the order of tens of microns allow multiple compositions to be analyzed in one field of view, thereby reducing the number of experiments, ensuring identical flow conditions, and enabling simultaneous incorporation of controls. We show that the presence of a long poly(ethylene glycol) (PEG) tether (MW 2000) between the lipid and ligand results in higher detachment resistances as compared to a short six-carbon spacer.
为实现高效靶向，含有药物或成像剂的载体必须具备促进与靶点结合的表面特性，同时阻止免疫系统的快速清除。在此，我们描述了一种通用技术，可在相同流动条件下同时比较载体表面组成对结合特性的影响。使用通过标准软光刻技术创建的微流控通道中的囊泡融合方法，形成模仿脂质体递送载体表面的支持脂质双层的平行通道。将囊泡储备溶液预混合并注入由可逆密封在载玻片上的聚二甲基硅氧烷（PDMS）印章形成的通道中，以创建不同组成的相邻通道。移除印章后，在将图案化基板组装到流动室进行结合研究之前，使用牛血清白蛋白（BSA）吸附层来防止双层扩散。该方法的优点包括能够轻松快速地从无限数量的脂质类型制备具有所需组成的双层，可选择特征尺寸，特征具有时间稳定性，以及非特异性结合低。几十微米量级的特征尺寸允许在一个视野中分析多种组成，从而减少实验次数，确保相同的流动条件，并能够同时纳入对照。我们表明，与短的六碳间隔基团相比，脂质与配体之间存在长的聚乙二醇（PEG）链（分子量2000）会导致更高的抗脱离性。
