Sung Ho Ha

Selective recovery of acetone-butanol-ethanol from aqueous mixture by pervaporation using immobilized ionic liquid polydimethylsiloxane membrane

An effective in situ recovery of acetone, butanol and ethanol (ABE) from fermentation broth is requisite to overcome the low productivity of ABE production. Pervaporation has proven to be one of the best methods for recovering ABE from fermentation broth. We fabricated an immobilized ionic liquid-polydimethylsiloxane (PDMS) membrane in which a [Tf2N]− based ionic liquid covalently bound to the PDMS backbone polymer and used it to recover ABE from aqueous solution by pervaporation. Permeate flux of immobilized IL-PDMS membrane was 7.8 times higher than that of conventional supported IL-PDMS membrane (where ILs are physically absorbed on the supported membrane). Butanol enrichment factor of immobilized IL-PDMS membrane was three-times higher than that of PDMS membrane. In addition, high enrichment factor both to acetone and ethanol as well as high operational stability of immobilized IL-PDMS membrane can enhance the efficacy of ABE recovery by employing this membrane.

Elucidation of molecular interactions between lipid membranes and ionic liquids using model cell membranes

Ionic liquids (ILs) are often considered to be green solvents based on their unusual stability, although their toxicity to living organisms has become an emerging issue based on a number of recent studies. We assume that one of the main reasons for this high level of cell toxicity is the molecular interactions between ILs and cell membranes. In this study, we used model cells to demonstrate that ILs can incorporate into lipid membranes, resulting in the perturbation of membrane structure. We employed various methods to elucidate the molecular interactions between cell membranes and ILs. Our results demonstrate that the stability of cell membranes is inversely related to the alkyl chain length and concentration of ILs, providing important information for the design of greener and safer ILs.

Mathematical analysis of colonial formation of embryonic stem cells in microfluidic system

A fluidic environment affects mechanochemical characteristics of embryonic stem cells (ESCs). Perfusion is recognized as an attractive culture mode of ESCs since the steady fluidic state can enhance ESCs’ controllability, supporting a unique cell culture condition. Cellular membrane motility presents important information about cellular dynamics such as adhesion, spreading, and migration. Thus, an investigation of the perfusion-induced membrane motility is significant to understand the mechanochemical behavior of ESCs in the steady culture state. In this research, we suggest Lfr, the ratio of circumferential membrane unattached to other cells’ to the cell’s circumference, as a new parameter to characterize cells’ shape and motility. Lfr of embryonic stem cells has positive correlations with cellular area (Ar) and free peripheral length (Lf) but a negative correlation with roundness (Rn). We also propose a mathematical model representing ESCs’ membrane motilities and demonstrate their colonical behavior.