Ma Guangzhong, Wan Zijian, Zhu Hao, Tao Nongjian
Biodesign Center for Biosensors and Bioelectronics , Arizona State University , Tempe , Arizona 85287 , USA . Email:
School of Electrical, Computer and Energy Engineering , Arizona State University , Tempe , Arizona 85287 , USA.
Chem Sci. 2019 Dec 11;11(5):1283-1289. doi: 10.1039/c9sc05434k. eCollection 2020 Feb 7.
Tethering a particle to a surface with a single molecule allows detection of the molecule and analysis of molecular conformations and interactions. Understanding the dynamics of the system is critical to all applications. Here we present a plasmonic imaging study of two important forces that govern the dynamics. One is entropic force arising from the conformational change of the molecular tether, and the other is solvent damping on the particle and the molecule. We measure the response of the particle by driving it into oscillation with an alternating electric field. By varying the field frequency, we study the dynamics on different time scales. We also vary the type of the tether molecule (DNA and polyethylene glycol), size of the particle, and viscosity of the solvent, and describe the observations with a model. The study allows us to derive a single parameter to predict the relative importance of the entropic and damping forces. The findings provide insights into single molecule studies using not only tethered particles, but also other approaches, including force spectroscopy using atomic force microscopy and nanopores.
用单个分子将粒子束缚在表面上，能够检测该分子并分析分子构象及相互作用。了解系统的动力学对所有应用都至关重要。在此，我们展示了一项关于控制动力学的两种重要力的等离子体成像研究。一种是由分子系链的构象变化产生的熵力，另一种是粒子和分子上的溶剂阻尼。我们通过用交变电场驱动粒子振荡来测量粒子的响应。通过改变场频率，我们研究不同时间尺度上的动力学。我们还改变系链分子的类型（DNA和聚乙二醇）、粒子大小以及溶剂粘度，并用一个模型描述观测结果。该研究使我们能够推导出一个单一参数来预测熵力和阻尼力的相对重要性。这些发现不仅为使用束缚粒子的单分子研究，也为包括使用原子力显微镜和纳米孔的力谱学在内的其他方法提供了见解。
