Agarwal Siddharth, Dizani Mahdi, Osmanovic Dino, Franco Elisa
Department of Mechanical and Aerospace Engineering, University of California at Los Angeles, Los Angeles, CA 90024, USA.
Department of Bioengineering, University of California at Los Angeles, Los Angeles, CA 90024, USA.
Interface Focus. 2023 Aug 11;13(5):20230017. doi: 10.1098/rsfs.2023.0017. eCollection 2023 Oct 6.
Living cells regulate many of their vital functions through dynamic, membraneless compartments that phase separate (condense) in response to different types of stimuli. In synthetic cells, responsive condensates could similarly play a crucial role in sustaining their operations. Here we use DNA nanotechnology to design and characterize artificial condensates that respond to light. These condensates form via the programmable interactions of star-shaped DNA subunits (nanostars), which are engineered to include photo-responsive protection domains. In the absence of UV irradiation, the nanostar interactions are not conducive to the formation of condensates. UV irradiation cleaves the protection domains, increases the nanostar valency and enables condensation. We demonstrate that this approach makes it possible to tune precisely the kinetics of condensate formation by dosing UV exposure time. Our experimental observations are complemented by a computational model that characterizes phase transitions of mixtures of particles of different valency, under changes in the mixture composition and bond interaction energy. In addition, we illustrate how UV activation is a useful tool to control the formation and size of DNA condensates in emulsion droplets, as a prototype organelle in a synthetic cell. This research expands our capacity to remotely control the dynamics of DNA-based components via physical stimuli and is particularly relevant to the development of minimal artificial cells and responsive biomaterials.
活细胞通过动态的、无膜区室来调节许多重要功能，这些区室会根据不同类型的刺激发生相分离（凝聚）。在合成细胞中，响应性凝聚物同样可能在维持其运作方面发挥关键作用。在此，我们利用DNA纳米技术设计并表征对光有响应的人工凝聚物。这些凝聚物通过星形DNA亚基（纳米星）的可编程相互作用形成，这些纳米星经过设计，包含光响应保护结构域。在没有紫外线照射的情况下，纳米星之间的相互作用不利于凝聚物的形成。紫外线照射会切割保护结构域，增加纳米星的价态并促使凝聚发生。我们证明，这种方法能够通过控制紫外线照射时间精确调节凝聚物形成的动力学。我们的实验观察结果得到了一个计算模型的补充，该模型描述了在混合物组成和键相互作用能发生变化时，不同价态颗粒混合物的相变情况。此外，我们还展示了紫外线激活作为一种有用工具，如何控制乳液滴中DNA凝聚物的形成和大小，乳液滴可作为合成细胞中的一种原型细胞器。这项研究扩展了我们通过物理刺激远程控制基于DNA的组件动态的能力，对最小化人工细胞和响应性生物材料的开发尤为重要。
