School of Materials Science and Engineering , Nanyang Technological University , 50 Nanyang Avenue 639798 , Singapore.
School of Chemical Engineering , Sungkyunkwan University , Suwon 16419 , Republic of Korea.
Langmuir. 2019 Aug 13;35(32):10658-10666. doi: 10.1021/acs.langmuir.9b01644. Epub 2019 Aug 1.
The deposition of two-dimensional bicellar disks on hydrophilic surfaces is an emerging approach to fabricate supported lipid bilayers (SLBs) that requires minimal sample preparation, works at low lipid concentrations, and yields high-quality SLBs. While basic operating steps in the fabrication protocol mimic aspects of the conventional vesicle fusion method, lipid bicelles and vesicles have distinct architectural properties, and understanding how experimental parameters affect the efficiency of bicelle-mediated SLB formation remains to be investigated. Herein, using the quartz crystal microbalance-dissipation and localized surface plasmon resonance techniques, we investigated the effect of bulk NaCl concentration on bicelle-mediated SLB formation on silicon dioxide surfaces. For comparison, similar experiments were conducted with vesicles as well. In both cases, SLB formation was observed to occur rapidly provided that the NaCl concentration was sufficiently high (>50 mM). Under such conditions, the effect of NaCl concentration on SLB formation was minor in the case of bicelles and significant in the case of vesicles where it is expected to be related primarily to osmotic pressure. At lower NaCl concentrations, bicelles also formed SLBs but slowly, whereas adsorbed vesicles remained intact. These findings were complemented by time-lapsed fluorescence microscopy imaging and fluorescence recovery after photobleaching measurements that corroborated bicelle-mediated SLB formation across the range of tested NaCl concentrations. The results are discussed by comparing the architectural properties of bicelles and vesicles along with theoretical analysis of the corresponding adsorption kinetics.
二维双分子层盘在亲水表面上的沉积是一种新兴的方法，用于制备支持脂质双层（SLB），这种方法需要最少的样品制备，在低脂质浓度下工作，并产生高质量的 SLB。虽然制造协议中的基本操作步骤模仿了传统囊泡融合方法的某些方面，但脂质双分子层和囊泡具有不同的结构特性，并且了解实验参数如何影响双分子层介导的 SLB 形成的效率仍有待研究。在此，我们使用石英晶体微天平耗散和局域表面等离子体共振技术，研究了 bulk NaCl 浓度对二氧化硅表面上双分子层介导的 SLB 形成的影响。为了进行比较，我们还使用囊泡进行了类似的实验。在这两种情况下，只要 NaCl 浓度足够高（>50 mM），就可以观察到 SLB 快速形成。在这种条件下，NaCl 浓度对双分子层形成的影响在双分子层的情况下较小，而在囊泡的情况下则较大，这主要与渗透压有关。在较低的 NaCl 浓度下，双分子层也可以形成 SLB，但速度较慢，而吸附的囊泡则保持完整。这些发现通过时间分辨荧光显微镜成像和光漂白后荧光恢复测量得到了补充，该测量证实了在测试的 NaCl 浓度范围内双分子层介导的 SLB 形成。通过比较双分子层和囊泡的结构特性以及相应吸附动力学的理论分析，对结果进行了讨论。
