Shinji Sugiura

Affinity extraction of proteins with a reversed micellar system composed of Cibacron Blue-modified lecithin.

Crude soybean lecithin was used as a novel surfactant to form reversed micelles in n-hexane. Cibacron Blue F-3GA (CB) was directly immobilized to the reversed micelles by a two-phase reaction. The reversed micellar system without CB showed low solubilizing capacity for low molecular weight proteins, lysozyme, and cytochrome c due to the weak electrostatic interactions. The introduction of CB significantly increased the solubilization of lysozyme because of its affinity binding to CB but showed no effect on the solubilization of cytochrome c since it did not bind to CB. Although bovine serum albumin had an affinity for CB, it was not extracted to the reversed micelles containing CB because its high molecular weight resulted in a significant steric hindrance effect. Thus the reversed micellar system had a high selectivity resulting from both biospecific and steric hindrance effects. The extraction yield of lysozyme decreased significantly with increasing ionic strength. Therefore, the back extraction of lysozyme was carried out using a stripping solution with an ionic strength of 0.865 mol/L. The overall recovery yield of lysozyme after back extraction could be increased to 87% by stripping for 2 h. The recovered lysozyme exhibited an activity equivalent to native lysozyme, and its secondary structure was also unchanged.

Formation of biocompatible reversed micellar systems using phospholipids

Formation of reversed micellar systems using biocompatible components was revealed by a significant increase of water content in the organic phase. Soybean lecithin (SL), which is a mixture of different phospholipids, and phosphatidylcholine (PC) purified from soybean were used as the amphiphilic molecule. Fatty acid and fatty acid ethyl esters were used as the organic solvent. Reversed micelles were formed in the following combinations of (amphiphilic molecule)/(organic solvent): SL/ethyl caproate, SL/ethyl oleate, SL/ethyl linoleate, PC/ethyl caproate, and PC/oleic acid. Characterization of the micelles using small angle X-ray scattering analysis was presented. Reversed micelles formed in SL/ethyl caproate, SL/ethyl oleate, and PC/ethyl caproate systems were spherical. Their radius of gyration was about 40Å when the water concentration in the organic phase was maximal. Maximal water concentrations in SL/ethyl caproate and PC/ethyl caproate reversed micellar systems decreased with increasing salt concentration in the aqueous phase. Micelle sizes also decreased with increased salt concentration. The extraction of protein cytochrome c using the reversed micellar system was demonstrated. Application of these reversed micellar systems will expand to pharmaceutical and food industries.

Monodispersed Droplet Formation Caused by Interfacial Tension from Microfabricated Channel Array

Emulsions have been utilized in various industries. Physical and qualitative stability depend on their size and size distribution. Stability and resistance to creaming of emulsions are influenced by their size.1, 2 Furthermore, size and size distribution determine the characteristics and abilities of emulsions. Rheology, appearance, chemical reactivity, and physical properties are influenced by both the average size and size distribution.1, 3 Monodispersed emulsions are applicable to valuable materials, such as drug delivery vehicles and as precursors of monodispersed beads for column chromatography. Monodispersed emulsions are also useful for fundamental studies because the interpretation of experimental results is much simpler than that for polydispersed emulsions.1 However, size control of these MS is not so easy.

Application of Microfluidics in Stem Cell Culture

In this chapter, we review the recent developments, including our studies on the micro‐ fabricated devices applicable to stem cell culture. We will focus on the application of plu‐ ripotent stem cells including embryonic stem cells and induced pluripotent stem cells. In the first section, we provide a background on microfluidic devices, including their fabri‐ cation technology, characteristics, and the advantages of their application in stem cell cul‐ ture. The second section outlines the use of micropatterning technology in stem cell culture. The use of microwell array technology in stem cell culture is explored in the third section. In the fourth section, we discuss the use of the microfluidic perfusion culture sys‐ tem for stem cell culture, and the last section is a summary of the current state of the art and perspectives of microfluidic technologies in stem cell culture.