Ionic Liquid Interface as A Cell Scaffold.

In sharp contrast to conventional solid/hydrogel platforms, water-immiscible liquids, such as perfluorocarbons and silicones, allow the adhesion of mammalian cells via protein nanolayers (PNLs) formed at the interface. However, fluorocarbons and silicones, which have been typically used for liquid cell culture, possess only narrow ranges of physicochemical parameters and have not allowed for a wide variety of cell culturing environment. In this paper, we propose that water-immiscible ionic liquids (ILs) are a new family of liquid substrate with tunable physicochemical properties and high solvation capabilities. Tetraalkylphosphonium-based ILs have been identified as non-cytotoxic ILs, whereon human mesenchymal stem cells (hMSCs) were successfully cultured. By reducing the cation charge distribution, or ionicity, via alkyl chain elongation, the interface allowed cell spreading with matured focal contacts. High-speed atomic force microscopy observations of the PNL formation process suggested that the cation charge distribution significantly altered the protein adsorption dynamics, which were associated with the degree of protein denaturation and the PNL mechanics. Moreover, by exploiting ILs dissolution capability, we fabricated an ion-gel cell scaffold. This enables us to further identify the significant contribution of bulk subphase mechanics to cellular mechanosensing in liquid-based culture scaffolds. This article is protected by copyright. All rights reserved.