Gelling without Structuring: A SAXS Study of the Interactions among DNA Nanostars

Francesco Spinozzi*, Maria Grazia Ortore, Giovanni Nava, Francesca Bomboi, Federica Carducci, Heinz Amenitsch, Tommaso Bellini*, Francesco Sciortino, Paolo Mariani

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Pages (from-to)10387-10396
Number of pages10
Issue number35
Publication statusPublished - 8 Sept 2020

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Materials Science(all)
  • Spectroscopy
  • Surfaces and Interfaces
  • Electrochemistry

Fields of Expertise

  • Advanced Materials Science

Treatment code (Nähere Zuordnung)

  • Basic - Fundamental (Grundlagenforschung)

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