Faysal K M Rifat, Park June S, Nguyen Jonny, Garcia Luis, Subramaniam Anand Bala
Department of Physics, School of Natural Sciences, University of California Merced, Merced, CA, United States of America.
Department of Bioengineering, School of Engineering, University of California, Merced, Merced, CA, United States of America.
PLoS One. 2017 Jan 4;12(1):e0169487. doi: 10.1371/journal.pone.0169487. eCollection 2017.
Although it is well known that phospholipids self-assemble on hydrophilic plasma-oxidized PMDS surfaces (ox-PDMS) to form cell membrane mimetic bilayers, the temporal stability of phospholipid membranes on these surfaces is unknown. Here we report that phospholipid bilayers remain stable on solvent-cleaned ox-PDMS for at least 132 hours after preparation. Absent solvent cleaning, the bilayers were stable for only 36 hours. We characterized the phospholipid bilayers, i) through quantitative comparative analysis of the fluorescence intensity of phospholipid bilayers on ox-PDMS and phospholipid monolayers on native PDMS and, ii) through measurements of the diffusive mobility of the lipids through fluorescence recovery after photobleaching (FRAP). The fluorescence intensity of the phospholipid layer remained consistent with that of a bilayer for 132 hours. The evolution of the diffusive mobility of the phospholipids in the bilayer on ox-PDMS over time was similar to lipids in control bilayers prepared on glass surfaces. Solvent cleaning was essential for the long-term stability of the bilayers on ox-PDMS. Without cleaning in acetone and isopropanol, phospholipid bilayers prepared on ox-PDMS surfaces peeled off in large patches within 36 hours. Importantly, we find that phospholipid bilayers supported on solvent-cleaned ox-PDMS were indistinguishable from phospholipid bilayers supported on glass for at least 36 hours after preparation. Our results provide a link between the two common surfaces used to prepare in vitro biomimetic phospholipid membranes-i) glass surfaces used predominantly in fundamental biophysical experiments, for which there is abundant physicochemical information, with ii) ox-PDMS, the dominant material used in practical, applications-oriented systems to build micro-devices, topographically-patterned surfaces, and biosensors where there is a dearth of information.
尽管众所周知磷脂会在亲水性的等离子体氧化聚二甲基硅氧烷表面（ox-PDMS）上自组装形成模拟细胞膜的双层膜，但这些表面上磷脂膜的时间稳定性尚不清楚。在此我们报告，制备后磷脂双层在溶剂清洗过的ox-PDMS上至少可保持稳定132小时。若不进行溶剂清洗，双层膜仅能稳定36小时。我们对磷脂双层进行了表征，一是通过对ox-PDMS上磷脂双层和天然PDMS上磷脂单层的荧光强度进行定量比较分析，二是通过光漂白后荧光恢复（FRAP）测量脂质的扩散迁移率。磷脂层的荧光强度在132小时内保持与双层膜一致。ox-PDMS上双层膜中磷脂扩散迁移率随时间的变化与在玻璃表面制备的对照双层膜中的脂质相似。溶剂清洗对于ox-PDMS上双层膜的长期稳定性至关重要。若不使用丙酮和异丙醇进行清洗，在ox-PDMS表面制备的磷脂双层膜会在36小时内大片剥落。重要的是，我们发现，在制备后至少36小时内，溶剂清洗过的ox-PDMS上支撑的磷脂双层与玻璃上支撑的磷脂双层并无区别。我们的结果在用于制备体外仿生磷脂膜的两种常见表面之间建立了联系，一是主要用于基础生物物理实验的玻璃表面，对此有丰富的物理化学信息，二是ox-PDMS，这是用于构建微型设备、具有拓扑图案的表面和生物传感器的实际应用导向系统中使用的主要材料，而关于它的信息却很匮乏。
