Spinozzi Francesco, Ortore Maria Grazia, Nava Giovanni, Bomboi Francesca, Carducci Federica, Amenitsch Heinz, Bellini Tommaso, Sciortino Francesco, Mariani Paolo
Department of Life and Environmental Sciences, Polytechnic University of Marche, 60131 Ancona, Italy.
Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, 20133 Milan, Italy.
Langmuir. 2020 Sep 8;36(35):10387-10396. doi: 10.1021/acs.langmuir.0c01520. Epub 2020 Aug 25.
We evaluate, by means of synchrotron small-angle X-ray scattering, the shape and mutual interactions of DNA tetravalent nanostars as a function of temperature in both the gas-like state and across the gel transition. To this end, we calculate the form factor from coarse-grained molecular dynamics simulations with a novel method that includes hydration effects; we approximate the radial interaction of DNA nanostars as a hard-sphere potential complemented by a repulsive and an attractive Yukawa term; and we predict the structure factors by exploiting the perturbative random phase approximation of the Percus-Yevick equation. Our approach enables us to fit all the data by selecting the particle radius and the width and amplitude of the attractive potential as free parameters. We determine the evolution of the structure factor across gelation and detect subtle changes of the effective interparticle interactions, that we associate to the temperature and concentration dependence of the particle size. Despite the approximations, the approach here adopted offers new detailed insights into the structure and interparticle interactions of this fascinating system.
我们通过同步加速器小角X射线散射，研究了DNA四价纳米星在气态和凝胶转变过程中形状及相互作用随温度的变化。为此，我们采用一种包含水合效应的新方法，从粗粒度分子动力学模拟中计算形状因子；我们将DNA纳米星的径向相互作用近似为硬球势，并辅以排斥和吸引的 Yukawa 项；我们利用 Percus-Yevick 方程的微扰随机相位近似来预测结构因子。我们的方法使我们能够通过选择粒子半径以及吸引势的宽度和幅度作为自由参数来拟合所有数据。我们确定了凝胶化过程中结构因子的演变，并检测到有效粒子间相互作用的细微变化，我们将其与粒子大小的温度和浓度依赖性联系起来。尽管存在近似，但这里采用的方法为这个迷人系统的结构和粒子间相互作用提供了新的详细见解。
