Systematic Computational and Experimental Investigation of Lithium-Ion Transport Mechanisms in Polyester-Based Polymer Electrolytes.

Understanding the mechanisms of lithium-ion transport in polymers is crucial for the design of polymer electrolytes. We combine modular synthesis, electrochemical characterization, and molecular simulation to investigate lithium-ion transport in a new family of polyester-based polymers and in poly(ethylene oxide) (PEO). Theoretical predictions of glass-transition temperatures and ionic conductivities in the polymers agree well with experimental measurements. Interestingly, both the experiments and simulations indicate that the ionic conductivity of PEO, relative to the polyesters, is far higher than would be expected from its relative glass-transition temperature. The simulations reveal that diffusion of the lithium cations in the polyesters proceeds via a different mechanism than in PEO, and analysis of the distribution of available cation solvation sites in the various polymers provides a novel and intuitive way to explain the experimentally observed ionic conductivities. This work provides a platform for the evaluation and prediction of ionic conductivities in polymer electrolyte materials.

Tag-free microfluidic separation of cells against multiple markers.

Conventional cell separation against multiple markers generally requires the attachment of antibody tags, typically fluorescent or magnetic, to selected cell types in a heterogeneous suspension. This work describes how such separation can be accomplished in a series of microfluidic systems without the need for such tags. Two capture stages containing antibody-functionalized alginate hydrogels are utilized for the isolation of CD34+ and Flk1+ cells from untreated, whole human blood. The capture-release capability of these degradable coatings is harnessed by a mixing chamber and a simple valving system such that the suspension emerging from the first capture stage is prepared for the second capture stage for further enrichment. With this configuration, we demonstrate the isolation of CD34+/Flk1+ endothelial progenitor cells from blood enabled by the depletion of CD34+/Flk1-hematopoietic stem cells population. This ability to achieve isolation of cells against multiple markers in an untagged separation method is of particular significance in applications involving cell implantation-based therapeutics including tissue engineering and molecular analysis.