title: Synthesis and characterization of a hydrogel with controllable electroosmosis: a potential brain tissue surrogate for electrokinetic transport.
abstract: Electroosmosis is the bulk fluid flow initiated by application of an electric field to an electrolyte solution in contact with immobile objects with a nonzero ζ-potential such as the surface of a porous medium. Electroosmosis may be used to assist analytical separations. Several gel-based systems with varying electroosmotic mobilities have been made in this context. A method was recently developed to determine the ζ-potential of organotypic hippocampal slice cultures (OHSC) as a representative model for normal brain tissue. The ζ-potential of the tissue is significant. However, determining the role of the ζ-potential in solute transport in tissue in an electric field is difficult because the tissue's ζ-potential cannot be altered. We hypothesized that mass transport properties, namely the ζ-potential and tortuosity, could be modulated by controlling the composition of a set of hydrogels. Thus, poly(acrylamide-co-acrylic acid) gels were prepared with three compositions (by monomer weight percent): acrylamide/acrylic acid 100/0, 90/10, and 75/25. The ζ-potentials of these gels at pH 7.4 are distinctly different, and in fact vary approximately linearly with the weight percent of acrylic acid. We discovered that the 25% acrylic acid gel is a respectable model for brain tissue, as its ζ-potential is comparable to the OHSC. This series of gels permits the experimental determination of the importance of electrokinetic properties in a particular experiment or protocol. Additionally, tortuosities were measured electrokinetically and by evaluating diffusion coefficients. Hydrogels with well-defined ζ-potential and tortuosity may find utility in biomaterials and analytical separations, and as a surrogate model for OHSC and living biological tissues.
authors: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States.
authors: Amir H
authors: AH
authors: Faraji
authors: Jonathan J
authors: JJ
authors: Cui
authors: Yifat
authors: Y
authors: Guy
authors: Ling
authors: L
authors: Li
authors: Colleen A
authors: CA
authors: Gavigan
authors: Timothy G
authors: TG
authors: Strein
authors: Stephen G
authors: SG
authors: Weber
mesh_terms: D000179:Acrylates / Q000737:chemistry*; D004058:Diffusion; D053841:Electroosmosis; D006624:Hippocampus / Q000378:metabolism*; D020100:Hydrogels; D006863:Hydrogen-Ion Concentration
chemical_list: D000179:Acrylates; D020100:Hydrogels; C036658:acrylic acid