The taxis of microscale objects in response to environmental chemical gradients represents a fundamental step toward the construction and programming of motile cytomimetic agents. Here, we demonstrate that various modes of autonomous oscillatory movement can be implemented across stratified chemical media by sensory-mediated actuation of protocell buoyancy. We use enzyme-powered peptide/polynucleotide protocells as microscale agents that sense and move in response to stationary or diffusive chemical fronts present in their local environment. By using stratified sucrose density gradients of antagonistic enzyme substrates, sustainable non-harmonic oscillatory movements, short-lived quasi-harmonic trajectories, damped harmonic behaviors, and states of protocell levitation are implemented under non-equilibrium conditions. Furthermore, transitions from harmonic to damped oscillatory trajectories provide a spatiotemporal mechanism for transient protocell-mediated reactivity and execute protocell logistics using an oscillatory cell-like transporter capable of repeated pick-up and delivery of molecular cargo. Our work provides opportunities for the development of soft microrobotics and sensing/delivery microscale agents.

中文翻译：

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分层化学介质中感觉原始细胞的自主振荡运动

微型物体对环境化学梯度的反应代表了构建和编程运动细胞模拟剂的基本步骤。在这里，我们证明了通过感觉介导的原始细胞浮力驱动，可以在分层化学介质中实现各种自主振荡运动模式。我们使用酶驱动的肽/多核苷酸原始细胞作为微型试剂，感知并移动以响应当地环境中存在的静止或扩散化学前沿。通过使用拮抗酶底物的分层蔗糖密度梯度，在非平衡条件下实现了可持续的非谐波振荡运动、短暂的准谐波轨迹、阻尼谐波行为和原始细胞悬浮状态。此外，从谐波到阻尼振荡轨迹的转变为瞬态原始细胞介导的反应性提供了时空机制，并使用能够重复拾取和递送分子货物的振荡细胞样转运蛋白来执行原始细胞物流。我们的工作为软体微型机器人和传感/输送微型代理的开发提供了机会。