Phase behaviour in complementary DNA-coated gold nanoparticles and fd-viruses mixtures: a numerical study

Area of Science:

• Colloidal science
• Materials science
• Biophysics

Background:

• A novel gel-forming colloidal system utilizes fd-viruses and DNA-functionalized gold nanoparticles.
• This system forms a highly porous gel upon cooling, offering potential as a tunable functional material.

Purpose of the Study:

• To elucidate the gelation mechanism of this binary colloidal system.
• To explore the equilibrium phase diagram using computational modeling.

Main Methods:

• Development of a computational model mimicking the experimental binary mixture of hard rods (fd-viruses) and hard spheres (gold nanoparticles).
• Application of Monte Carlo simulations to investigate the system's phase behavior and gelation pathways.
• Analysis of phase separation mechanisms, including nucleation-and-growth and spinodal decomposition.

Main Results:

• The model predicts phase separation under experimental conditions, occurring via nucleation-and-growth or spinodal decomposition.
• Spinodal decomposition leads to the formation of small clusters that aggregate into a percolating network.
• Evidence suggests gelation proceeds through an arrested spinodal decomposition mechanism.

Conclusions:

• The study provides insights into the gelation mechanism of DNA-functionalized fd-virus and gold nanoparticle mixtures.
• The findings support the hypothesis of arrested spinodal decomposition driving gel formation in this system.
• This understanding is crucial for designing and controlling the properties of such tunable porous materials.