Svetoslav Nikolov1 Alberto Fernandez-Nieves2 Alexander Alexeev1

1, Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
2, School of Physics, Georgia Institute of Technology, Atlanta, Georgia, United States

Advancements in nanotechnology over the last two decades have allowed researchers to tackle a number of critical biomedical problems on the microscale, like site-specific drug delivery and micro-sensing. Microdevices which can selectively capture nanoparticles at a given rate are particularly interesting as they are critical for the development of enzymatic bioreactors which are used in many in vivo micro-sensing applications. These devices could also be used for origin of life studies, where the ability to bring in particles at predefined rates can be used to carry out complex chemical reactions. In our work, using dissipative particle dynamics, we leverage the large volume changes of microgels to design a novel microdevice which can be used for nanoparticle capture. Our device is made up of a perforated rigid spherical shell that is embedded with a spherical microgel. Upon application of an external stimulus the gel swells, expanding through the perforated holes and making contact with the external nanoparticle rich solution. After removal of the external stimulus the microgel collapses into the shell interior, bringing along with it nanoparticles from the external solution. The area around each of the perforations is functionalized with a polymer brush which is used to achieve chemical gating, when the gel is in the collapsed state. We study how the capture rate depends on the swelling period and gel-nanoparticle interactions and we quantify the optimal swelling period which maximizes capture rates.

Project supported by the National Science Foundation of U.S.A. (DMR-1255288, TG-DMR180038, and DGE-1650044)