Transformations in crystals of DNA-functionalized nanoparticles by electrolytes

Area of Science:

• Colloid and interface science
• Materials science
• Physical chemistry

Background:

• Colloidal crystals are crucial for water treatment technologies like purification and desalination.
• Understanding colloid interactions with varying electrolyte concentrations is essential for optimizing these applications.

Purpose of the Study:

• To investigate the assembly and phase behavior of DNA-grafted gold nanoparticles in concentrated electrolyte solutions.
• To elucidate the relationship between electrolyte concentration, interparticle interactions, and crystal structure.

Main Methods:

• Studied the assembly of DNA-grafted gold nanoparticles in solutions with varying divalent Ca2+ ion concentrations.
• Employed molecular dynamics simulations to analyze interparticle interactions.
• Utilized thermodynamic analysis to assess environmental changes.

Main Results:

• Increasing Ca2+ concentration induced a phase transition from face-centered-cubic (FCC) to body-centered-cubic (BCC) crystal structures.
• Molecular dynamics revealed a shift from repulsive to attractive interparticle forces with increasing electrolyte concentration.
• Thermodynamic analysis indicated significant dehydration of the nanoparticle environment at higher salt concentrations.

Conclusions:

• The transition to BCC structures is favored by attractive intercolloid interactions and dehydrated states, driven by increased salt concentration.
• Findings provide insights into the salting-out phenomenon observed in colloidal systems like proteins.