Transformations in crystals of DNA-functionalized nanoparticles by electrolytes

Roger John-Erik Reinertsen, Felipe Jiménez-Ángeles, Sumit Kewalramani, Michael Bedzyk, Monica Olvera de la Cruz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Colloidal crystals have applications in water treatments, including water purification and desalination technologies. It is, therefore, important to understand the interactions between colloids as a function of electrolyte concentration. We study the assembly of DNA-grafted gold nanoparticles immersed in concentrated electrolyte solutions. Increasing the concentration of divalent Ca2+ ions leads to the condensation of nanoparticles into face-centered-cubic (FCC) crystals at low electrolyte concentrations. As the electrolyte concentration increases, the system undergoes a phase change to body-centered-cubic (BCC) crystals. This phase change occurs as the interparticle distance decreases. Molecular dynamics analysis suggests that the interparticle interactions change from strongly repulsive to short-range attractive as the divalent-electrolyte concentration increases. A thermodynamic analysis suggests that increasing the salt concentration leads to significant dehydration of the nanoparticle environment. We conjecture that the intercolloid attractive interactions and dehydrated states favour the BCC structure. Our results gain insight into salting out of colloids such as proteins as the concentration of salt increases in the solution.

Original languageEnglish (US)
Pages (from-to)408-423
Number of pages16
JournalFaraday Discussions
StatePublished - Jun 16 2023

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry


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