Molecular-scale Breaking due to Repeated Loading in Molecular Shuttles

机器随着使用而降级的速度对它们的价值有很大影响。例如，由于对故障模式的勤奋研究和随后的设计改进，现代汽车的使用寿命比仅30年前制造的汽车长得多。纳米技术已经取得了进步，我们可以成功地制造纳米机器，如分子航天飞机：由生物分子马达提供动力的纳米级运输系统，能够运送分子货物。这个项目的目标是促进我们对限制这些分子航天飞机寿命的退化机制的理解。PIS的研究表明，“里程”很重要--每移动千分之一英寸的距离，分子航天飞机的长度就会缩小几纳米。在这个研究项目中，PI将调查这一过程是否也很重要，并让分子航天飞机通过越来越弯曲的微制造轨道，这会给它们的结构施加机械应力，并应该导致它们以更高的频率断裂。这些实验将提高对纳米机器一般降解机制的理解，使我们的“分子航天飞机”的设计得以改进，甚至可能为生物纳米机器如何降解和老化提供见解。该项目将整合本科研究人员和高中生，新的见解将被整合到一门新的纳米生物技术课程中。外展活动包括实验室活动和讲座，作为面向人数不足的高中生的暑期课程“纳米技术入门”的一部分，该项目以两个假设为指导。首先，我们的假设是，破裂事件将以机械力化学原理确定的平均速率随机发生。其次，我们的假设是，在工程环境中分子航天飞机的整体降解可以理解为微管组件的断裂和缩短的组合。为了验证这些假设，我们将观察到运动蛋白马达(我们基本的“分子穿梭”)通过微制造的引导结构移动的微管，这些结构对微管施加一定数量的恒定和循环应变。该项目的结果将是我们的视角潜在的变革性拓宽，从分子间键的物理启发的力谱(测量例如断裂力量)到工程启发的损伤累积的观点，这是纳米机械中机械应力的结果，这可能最终导致骨折。更直接的是，该项目的结果将帮助社区克服基于生物分子马达的纳米设备设计中有限的生命周期障碍。

The rate at which machines degrade with use has a large impact on their value. For example, modern cars last significantly longer than cars built only thirty years ago due to diligent research into failure modes and subsequent design improvements. Nanotechnology has progressed so that we can successfully build nanomachines such as 'molecular shuttles': nanoscale transport systems powered by biomolecular motors capable of delivering molecular cargo. The goal of this project is to advance our understanding of the degradation mechanisms limiting the lifetime of these molecular shuttles. The PIs research showed that 'mileage' matters - for every thousandth of an inch of distance moved, the molecular shuttle shrank a few nanometers in length. In this research project, the PIs will investigate if the course matters as well, and let the molecular shuttles travel through increasingly curvy microfabricated tracks which puts mechanical stress on their structure and should cause them to break at increasing frequencies. These experiments will improve understanding of degradation mechanisms for nanomachines in general, enable improvement of the design of our 'molecular shuttles', and may even provide insights into how biological nanomachines degrade and age. The project will integrate undergraduate researchers and high school students, and the new insights will be integrated into a new nanobiotechnology course. Outreach activities include lab activities and lectures as part of the 'Introduction to Nanotechnology' summer course for underrepresented high school students,The project is guided by two hypotheses. Firstly, it is our hypothesis that breaking events will occur stochastically at average rates determined by mechanochemical principles. Secondly, it is our hypothesis that the overall degradation of molecular shuttles in engineered environments can be understood as a combination of breaking and shortening of the microtubule component. To test these hypotheses, we will observe microtubules moved by kinesin motors (our basic 'molecular shuttle') through microfabricated guiding structures which exert a defined amount of constant and cyclic strain on the microtubule. The outcome of the project will be a potentially transformational broadening of our perspective from the physics-inspired force spectroscopy of intermolecular bonds (measuring e.g. rupture forces) to an engineering-inspired view of an accumulation of damage as result of mechanical stress in nanomachines, which may ultimately result in fracture. More immediately, the results of the project will help the community to overcome the limited lifetime roadblock in the design of nanodevices based on biomolecular motors.