Using Reactive Dissipative Particle Dynamics to Understand Local Shape Manipulation of Polymer Vesicles

Biological cells have long been of interest to researchers due to their ability to actively control their shape. Accordingly, there is significant interest in generating simplified synthetic protocells that can alter their shape in response to stimuli. To better understand the possible mechanisms of local morphological changes in a popular protocell system, the block copolymer vesicle, we developed a reaction-diffusion model that combines Dissipative Particle Dynamics (DPD) and the Split Reactive Brownian Dynamics algorithm (SRBD), which is capable of modeling the dynamics of polymer solution as they undergo chemical reactions. We investigated local morphological change driven by either the microinjection of a stimulus or an enzymatically-produced stimulus. The results suggest that localized inflation can be induced by either a solvent stimulus that swells the vesicle, or by a reactant stimulus that alters the chemistry of the block polymer. The latter technique results in a more persistent local deformation than the former, which we attribute to the slower diffusion of polymer chains relative to the solvent. Additionally, our method expands the capability of simulating the non-equilibrium behavior of polymer solutions on mesoscopic scales to include stochastic chemical kinetics.