title: Harnessing Cooperative Interactions between Thermoresponsive Aptamers and Gels To Trap and Release Nanoparticles.
abstract: We use computational modeling to design a device that can controllably trap and release particles in solution in response to variations in temperature. The system exploits the thermoresponsive properties of end-grafted fibers and the underlying gel substrate. The fibers mimic the temperature-dependent behavior of biological aptamers, which form a hairpin structure at low temperatures (T) and unfold at higher T, consequently losing their binding affinity. The gel substrate exhibits a lower critical solution temperature and thus, expands at low temperatures and contracts at higher T. By developing a new dissipative particle dynamics simulation, we examine the behavior of this hybrid system in a flowing fluid that contains buoyant nanoparticles. At low T, the expansion of the gel causes the hairpin-shaped fibers to extend into the path of the fluid-driven particle. Exhibiting a high binding affinity for these particles at low temperature, the fibers effectively trap and extract the particles from the surrounding solution. When the temperature is increased, the unfolding of the fiber and collapse of the supporting gel layer cause the particles to be released and transported away from the layer by the applied shear flow. Since the temperature-induced conformational changes of the fiber and polymer gel are reversible, the system can be used repeatedly to "catch and release" particles in solution. Our findings provide guidelines for creating fluidic devices that are effective at purifying contaminated solutions or trapping cells for biological assays.
authors.affiliation: Department of Chemical and Petroleum Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States.
authors.forename: Ya
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Materials Science and Engineering Department, Clemson University , Clemson, South Carolina 29634, United States.
authors.forename: Olga
authors.initials: O
authors.lastname: Kuksenok
authors.affiliation: Biodesign Institute, Arizona State University , Tempe, Arizona 85281, United States.|Materials Science and Engineering, School for Engineering of Matter, Transport and Energy, Arizona State University , Tempe, Arizona 85281, United States.
authors.forename: Ximin
authors.initials: X
authors.lastname: He
authors.affiliation: Wyss Institute for Biologically Inspired Engineering, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Aizenberg
authors.affiliation: Wyss Institute for Biologically Inspired Engineering, Harvard University , Cambridge, Massachusetts 02138, United States.|Department of Chemistry and Chemical Biology, Harvard University , Cambridge, Massachusetts 02138, United States.|School of Engineering and Applied Science, Harvard University , Cambridge, Massachusetts 02138, United States.|Kavli Institute for Bionano Science and Technology, Harvard University , Cambridge, Massachusetts 02138, United States.
authors.forename: Joanna
authors.initials: J
authors.lastname: Aizenberg
authors.affiliation: Department of Chemical and Petroleum Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States.
authors.forename: Anna C
authors.initials: AC
authors.lastname: Balazs
keywords: aptamers; catch-and-release system; dissipative particle dynamics simulations; microfluidic device; nanoparticles; thermoresponsive gel