Department of Bioengineering, University of California, Merced, Merced, California 95343, United States.
ACS Appl Mater Interfaces. 2020 Dec 16;12(50):56549-56561. doi: 10.1021/acsami.0c14485. Epub 2020 Dec 7.
To date, techniques for the assembly of phospholipid films into cell-like giant unilamellar vesicles (GUVs) use planar surfaces and require the application of electric fields or dissolved molecules to obtain adequate yields. Here, we present the use of nanocellulose paper, which are surfaces composed of entangled cylindrical nanofibers, to promote the facile and high yield assembly of GUVs. Use of nanocellulose paper results in up to a 100 000-fold reduction in costs while increasing yields compared to extant surface-assisted assembly techniques. Quantitative measurements of yields and the distributions of sizes using large data set confocal microscopy illuminates the mechanism of assembly. We present a thermodynamic "budding and merging", BNM, model that offers a unified explanation for the differences in the yields and sizes of GUVs obtained from surfaces of varying geometry and chemistry. The BNM model considers the change in free energy due to budding by balancing the elastic, adhesion, and edge energies of a section of a surface-attached membrane that transitions into a surface-attached spherical bud. The model reveals that the formation of GUVs is spontaneous on hydrophilic surfaces consisting of entangled cylindrical nanofibers with dimensions similar to nanocellulose fibers. This work advances understanding of the effects of surface properties on the assembly of GUVs. It also addresses practical barriers that currently impede the promising use of GUVs as vehicles for the delivery of drugs, for the manufacturing of synthetic cells, and for the assembly of artificial tissues at scale.
迄今为止，将磷脂膜组装成类似细胞的大单室脂质体（GUV）的技术使用平面表面，并需要施加电场或溶解分子以获得足够的产量。在这里，我们提出使用纳米纤维素纸，这是由纠缠的圆柱形纳米纤维组成的表面，以促进 GUV 的易于和高产组装。与现有的表面辅助组装技术相比，纳米纤维素纸的使用使成本降低了高达 100,000 倍，同时提高了产量。使用大的数据集共聚焦显微镜对产量和尺寸分布进行定量测量，阐明了组装的机制。我们提出了一种热力学“出芽和融合”（BNM）模型，该模型为从具有不同几何形状和化学性质的表面获得的 GUV 的产量和尺寸的差异提供了统一的解释。BNM 模型考虑了由出芽引起的自由能变化，通过平衡附着在表面的膜的一部分的弹性，粘附和边缘能来平衡，该部分膜过渡到附着在表面的球形芽。该模型表明，在由类似于纳米纤维素纤维的尺寸的纠缠的圆柱形纳米纤维组成的亲水表面上，GUV 的形成是自发的。这项工作增进了对表面性质对 GUV 组装影响的理解。它还解决了当前阻碍 GUV 作为药物输送载体，合成细胞制造以及在大规模上组装人工组织的有前途的用途的实际障碍。
