Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322 United States.
School of Physics and Astronomy, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO171BJ, U.K.
ACS Nano. 2021 May 25;15(5):8427-8438. doi: 10.1021/acsnano.0c10658. Epub 2021 May 6.
Synthetic motors that consume chemical energy to produce mechanical work offer potential applications in many fields that span from computing to drug delivery and diagnostics. Among the various synthetic motors studied thus far, DNA-based machines offer the greatest programmability and have shown the ability to translocate micrometer-distances in an autonomous manner. DNA motors move by employing a burnt-bridge Brownian ratchet mechanism, where the DNA "legs" hybridize and then destroy complementary nucleic acids immobilized on a surface. We have previously shown that highly multivalent DNA motors that roll offer improved performance compared to bipedal walkers. Here, we use DNA-gold nanoparticle conjugates to investigate and enhance DNA nanomotor performance. Specifically, we tune structural parameters such as DNA leg density, leg span, and nanoparticle anisotropy as well as buffer conditions to enhance motor performance. Both modeling and experiments demonstrate that increasing DNA leg density boosts the speed and processivity of motors, whereas DNA leg span increases processivity and directionality. By taking advantage of label-free imaging of nanomotors, we also uncover Lévy-type motion where motors exhibit bursts of translocation that are punctuated with transient stalling. Dimerized particles also demonstrate more ballistic trajectories confirming a rolling mechanism. Our work shows the fundamental properties that control DNA motor performance and demonstrates optimized motors that can travel multiple micrometers within minutes with speeds of up to 50 nm/s. The performance of these nanoscale motors approaches that of motor proteins that travel at speeds of 100-1000 nm/s, and hence this work can be important in developing protocellular systems as well next generation sensors and diagnostics.
合成马达利用化学能产生机械功，在从计算到药物输送和诊断的许多领域都有潜在的应用。在迄今为止研究的各种合成马达中，基于 DNA 的机器具有最大的可编程性，并显示出自主迁移微米距离的能力。DNA 马达通过采用烧桥布朗棘轮机制来移动，其中 DNA“腿”杂交，然后破坏固定在表面上的互补核酸。我们之前已经表明，与双足步行者相比，滚动的高度多价 DNA 马达具有更好的性能。在这里，我们使用 DNA-金纳米粒子缀合物来研究和增强 DNA 纳米马达的性能。具体来说，我们调整结构参数，如 DNA 腿密度、腿跨度和纳米粒子各向异性以及缓冲条件，以提高马达性能。模型和实验都表明，增加 DNA 腿密度可以提高马达的速度和进程，而 DNA 腿跨度则增加了进程和方向性。通过利用纳米马达的无标记成像，我们还揭示了莱维型运动，其中马达表现出突发的迁移，伴随着短暂的停顿。二聚化粒子也表现出更多的弹道轨迹，证实了滚动机制。我们的工作展示了控制 DNA 马达性能的基本特性，并展示了经过优化的马达，它们可以在几分钟内行驶多个微米，速度高达 50nm/s。这些纳米级马达的性能接近以 100-1000nm/s 速度行驶的马达蛋白的性能，因此这项工作在开发原细胞系统以及下一代传感器和诊断方面可能非常重要。
