Utilizing rheology to accelerate the discovery of biocompatible ionic liquids
Ionic liquids (ILs), i.e., low-melting-point liquid salts containing organic cations, can be conveniently synthesized to achieve tailor-made physical, chemical and biological properties. This tunability significantly expands the scope of healthcare materials beyond conventional molecular liquids. However, the large number of IL candidates also evidences a need of high-throughput tools to screen their biocompatibility and performance, which can hardly be fulfilled by conventional in vivo and ex vivo experiments and molecular dynamics simulations. We aim to address this challenge from an innovative rheological perspective: we utilize hydrodynamic interactions to perturb and measure forces and microstructures in ILs mixed with key biological components such as proteins, lipids and water. These mixtures are complex fluids due to ion clustering under electrostatic, hydrogen bonding and polar interactions. The microstructures we probe can then be linked to critical events determining the performance of ILs, such as protein aggregation and membrane lipid extraction. We are not only interested in answering fundamental questions about the physical properties of these novel mixtures, but also seek to utilize our findings in applications such as formulations of protein therapeutics with enhanced permeation.