Modeling Energy Transduction in Systems of Nanoparticle-Filled Polymeric Microcapsules

摘要

Biological cells can communicate with each other via molecules that are released by signaling cells and recognized by receptors on the surface of target cells. This form of communication enables groups of cells to perform complicated,concerted functions. Inspired by the signaling behavior of biological cells,we recently used theory and simulation to design self-propelled microcapsules that communicate with each other via nanoparticles . This synthetic system consists of a 1 signaling microcapsule that encases nanoparticles and an initially empty target capsule. Both microcapsules are immersed in a fluid and are localized on an initially homogenously adhesive substrate. Furthermore,at the onset,both capsules are stationary. As the nanoparticles diffuse from the interior of signaling capsule and into the surrounding fluid,they can adsorb onto the substrate. Here,we assume that the adhesive strength of the substrate is reduced by the adsorbed nanoparticles. Consequently,the adsorbed nanoparticles give rise to an adhesion gradient under the target capsule that propels this capsule to move along the substrate. Through hydrodynamic interaction between the capsules,the target capsule then effectively "pulls" the signaling capsule onto the adhesion gradient. This behavior creates a self-sustained motion of both the capsules,since the adhesion gradient is now propagated due to the movement of the signaling capsule,which continues to release the nanoparticles. In effect,the released nanoparticles provide the fuel that drives the concerted motion of both the capsules. In this sense,the system displays chemo-mechanical transduction,where the chemical energy produced by the adsorption of the nanoparticles is transduced into the mechanical motion of the capsules. Ultimately,the findings could enable researchers to fabricate small-scale devices that "cooperate" to display effective forms of self-actuation,sensing,and sharing of information.