CBES Investigators

Anna Balazs

Victor Yashin

Research Assistant Professor
Chemical and Petroleum Engineering

Badel Mbanga

Postdoctoral Fellow
Chemical and Petroleum Engineering

Henry Shum

Postdoctoral Fellow
Chemical and Petroleum Engineering

Research Overview

Polymer Grafted Nanoparticle Networks
We focus on a relatively new class of materials: polymer-grafted nanoparticles (PGNs) that are cross-linked into extensive networks. Specifically, PGNs are nanoparticles that are decorated with end-grafted polymers or “arms”; these arms bind to each other through end groups to form chains thatinterconnect the nanoparticles into an extensive network. These arms can be strands of DNA. We hypothesize that under an applied stress, the flexible, cross-linked polymer arms can provide a useful means of controlling the particle locations within the network and can potentially lead to new, unexplored particle arrangements. Importantly, we will “co-design” the PGN networks and the applied stresses. Namely, we will determine not only the optimal features of the network to maximize its response to a given stress, but also the optimal stress that fully exploits the materials structure to yield the desired behavior. Through interactions with the Szleifer group, we will obtain expressions for the interactions between the coated particles. Using these expressions, we will use our recently developed models for the macroscopic response of the PGN networks to mechanical deformation. These predictions could then be tested by the Mirkin group.

The repressilator regulatory network generates oscillations in chemical production from microcapsules. These oscillations can be harnessed to drive self-regulated assembly and collective migration of the microcapsules on a surface.

Our previous studies on communicating microcapsules involved two different types of capsules—signaling and target—which respectively released signaling promoters and inhibitors. Hence, these capsules interacted through a coupling of positive and negative feedback loops. We found that this system led to pronounced oscillations in the concentrations of the promoter and inhibitor species (nanoparticles) in the surrounding solution. These oscillations, in turn, led to the complex dynamical behavior. We are currently working with the Stupp group to help guide the experimental realization of this system. In new modeling studies, we will consider the behavior of three different types of capsules that interact through a cycle of negative feedback loops. The system is intriguing because the negative feedback could lead to cooperative behavior among the capsules. We will first consider stationary capsules on a surface. We will isolate the critical parameters—relative permeabilities of the capsules and initial concentrations of the released inhibitors—that leads to oscillations in the released species. We will then assume that a fraction of the released species bind to the underlying surface and will determine how these adsorbed species must modify the capsule-surface adhesion interactions in order for the capsules to undergo autonomous chemotactic motion (in response to gradients of adsorbed species on the surface).