Guoxi Zhu
“Characterizing the transition size in a two-step phase transition in DNA-coated colloids”
Guoxi Zhu, Huang Fang, W. Benjamin Roger
Brandeis / Physics
Hosted by Rogers' Lab
Abstract
Self-assembly is the process by which a disordered system organizes into an ordered state under thermal fluctuation as a consequence of interactions between the components themselves. In the Rogers Lab, we study self-assembly using a model experimental system combining small particles, called colloids, with single-stranded DNA. Specifically, we coat single-stranded DNA onto the surface of colloidal particles to introduce interactions between these particles and study the assembled structures that emerge. Complimentary DNA sequences coated on particles will bind to one another, which induces a specific attractive force between particles.
In our project, we study the two-dimensional self-assembly of these DNA-coated particles using molecular dynamics simulations, and explore the role of different interaction strengths in determining the structures that form. In these simulations, we observe a two-step phase transition during crystallization when like interactions are weak. The structure of the growing crystal transitions from a floppy square to a closely packed hexagonal structure as time passes. My work is to explore how the size of the crystal at the point at which it transitions from square to hexagonal, which we call the “transition size,” depends on the three pair interactions in the system.
Preliminary results suggest that the transition size appears to decrease with increasing like attraction. Going forward, we hope to compare these simulation results with free-energy calculations and experimental observations.
Support
SMURF (Summer MRSEC Undergrad Research Fellowship)