title: Autonomic molecular transport by polymer films containing programmed chemical potential gradients.
abstract: Materials which induce molecular motion without external input offer unique opportunities for spatial manipulation of molecules. Here, we present the use of polyacrylamide hydrogel films containing built-in chemical gradients (enthalpic gradients) to direct molecular transport. Using a cationic tertiary amine gradient, anionic molecules were directionally transported up to several millimeters. A 40-fold concentration of anionic molecules dosed in aerosol form on a substrate to a small region at the center of a radially symmetric cationic gradient was observed. The separation of mixtures of charged dye molecules was demonstrated using a boronic acid-to-cationic gradient where one molecule was attracted to the boronic acid end of the gradient, and the other to the cationic end of the gradient. Theoretical and computational analysis provides a quantitative description of such anisotropic molecular transport, and reveals that the gradient-imposed drift velocity is in the range of hundreds of nanometers per second, comparable to the transport velocities of biomolecular motors. This general concept of enthalpy gradient-directed molecular transport should enable the autonomous processing of a diversity of chemical species.
authors.affiliation: †Department of Materials Science and Engineering, Beckman Institute for Advanced Science and Technology, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
authors.forename: Chunjie
authors.initials: C
authors.lastname: Zhang
authors.affiliation: ‡Department of Biomedical Engineering, Columbia University, 1210 Amsterdam Avenue, New York, New York 10027, United States.
authors.forename: Amit
authors.initials: A
authors.lastname: Sitt
authors.affiliation: †Department of Materials Science and Engineering, Beckman Institute for Advanced Science and Technology, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
authors.forename: Hyung-Jun
authors.initials: HJ
authors.lastname: Koo
authors.affiliation: †Department of Materials Science and Engineering, Beckman Institute for Advanced Science and Technology, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
authors.forename: Kristopher V
authors.initials: KV
authors.lastname: Waynant
authors.affiliation: ‡Department of Biomedical Engineering, Columbia University, 1210 Amsterdam Avenue, New York, New York 10027, United States.
authors.forename: Henry
authors.initials: H
authors.lastname: Hess
authors.affiliation: §Defense Threat Reduction Agency, Fort Belvoir, Virginia 22060, United States.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Pate
authors.affiliation: †Department of Materials Science and Engineering, Beckman Institute for Advanced Science and Technology, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
authors.forename: Paul V
authors.initials: PV
authors.lastname: Braun
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D001897:Boronic Acids / Q000737:chemistry; D005591:Chemical Fractionation; D004058:Diffusion; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry; D006868:Hydrolysis; D007700:Kinetics; D015394:Molecular Structure; D010316:Particle Size; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D001897:Boronic Acids; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D000099166:Polyacrylamides