Functional Polymers and Colloids

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Synthetic polyampholytes, copolymers formed from anionic, cationic and neutral monomers, have fascinating solution properties that resemble those of an important class of proteins called Inherently Disordered Proteins. We will prepare series of non-stoichiometric polyampholytes based on acrylic monomers with a range of cation to anion ratios, and with different charge densities controlled by incorporation of neutral comonomers. We will explore the ability of these copolymers to phase separate as viscous liquid coacervates from aqueous solution, in response to subtle and often cooperative changes in salinity, pH, temperature, and presence of other polymers. These polyampholytes and their coacervates are highly cell compatible, and we will explore their use as components of synthetic extracellular matrices, with particular focus on their ability to fulfill the attachment needs of many mammalian cells. We have previously shown that such polyampholytes have significant potential as cell cryoprotectants. At the same time, we are developing highly hydrated polymer microgels, lightly crosslinked, optically transparent, spherical polymer gels of 5 to 20 micrometer diameter when swollen. These entities are formed by precipitation polymerization in marginal solvents, a unique process we originally developed, that results in radially structured, surfactant-free microgels. We now plan to explore the use of these microgels as granular components of extracellular matrices, in particular for assays to test migration of different cell types through tissue, including metastatic cancer cell, embryonic cells, and immune surveillance cells. This will involve microgels grafted with the above polyampholytes to allow better control over cell adhesion as well as visco-elastic properties of these synthetic 3D tissue mimics. Additional applications may involve using similar modified microgels with liquid coacervate cores as templates for cell-free biology using single absorbed enzymes as well as cell extracts. This work will involve collaborators with expertise in certain cell types, and could lead to useful approaches to better understand cell behaviour.