In situ measurement of thermodynamic partitioning in open hydrogels

Thermodynamic partitioning dictates solute loading and release from a hydrogel. Design of drug delivery vehicles, cell and tissue matrices, and immunoassay scaffolds that utilize hydrogel materials is informed by an understanding of the thermodynamic partitioning properties of those hydrogels. We develop aberration-compensated laser scanning confocal microscopy (AC-LSCM), a technique that can be applied to all fluorescence microscope-based equilibrium partition coefficient measurements where the fluorescence is uniformly distributed in the reference material (e.g., many solutes in thermodynamic equilibrium). In this paper, we use AC-LSCM to measure the spatially-resolved in situ equilibrium partition coefficients of various fluorescently-labeled solutes in single layer and multi-layer open hydrogels. In considering a dynamic material, we scrutinize solute interactions with a UV photoactive polyacrylamide gel that incorporates a benzophenone methacrylamide backbone. We observed strong agreement with an adj...