Yun Suk Huh

Selective extraction of acetic acid from the fermentation broth produced by Mannheimia succiniciproducens

Acetic acid is by-product from fermentation processes for producing succinic acid using Mannheimia succiniciproducens. To obtain pure succinic acid from the final fermentation broth, acetic acid was selectively removed based on the different extractability of succinic acid and acetic acid with pH using tri-n-octylamine (TOA) as extractant. When successive batch extractions were performed using 0.25xa0mol TOA kg−1 dissolved in 1-octanol at pH 5, the mol ratio of succinic acid to acetic acid before extraction was 4.9 and the final ratio after the fourth batch was 9.4.

Rapid separation of bacteriorhodopsin using a laminar-flow extraction system in a microfluidic device

A protein separation technology using the microfluidic device was developed for the more rapid and effective analysis of target protein. This microfluidic separation system was carried out using the aqueous two-phase system (ATPS) and the ionic liquid two-phase system (ILTPS) for purification method of the protein sample, and the three-flow desalting system was used for the removal of salts from the sucrose-rich sample. Partitioning of the protein sample was observed in ATPS or ILTPS with the various pHs. The microdialysis system was applied to remove small molecules, such as sucrose and salts in the microfluidic channel with the different flow rates of buffer phase. A complex purification method, which combines microdialysis and ATPS or ILTPS, was carried out for the effective purification of bacteriorhodopsin (BR) from the purple membrane of Halobacterium salinarium, which was then analyzed by sodium dodecyl sulfatepolyacrylamide gel electrophoresis and matrix-assisted laser desorptionionization time-of-flight. Furthermore, we were able to make a stable three-phase flow controlling the flow rate in the microfluidic channel. Our complex purification methods were successful in purifying and recovering the BR to its required value.

Removal of bovine serum albumin using solid-phase extraction with in-situ polymerized stationary phase in a microfluidic device.

Serum albumin, one of the most abundant serum proteins, blocks the expression of other important biomarkers. The objective of this study is to remove serum albumin effectively by using solid-phase extraction (SPE) in microfluidic devices. Photo-polymerized adsorbent as a stationary phase of SPE was used to remove bovine serum albumin (BSA). The adsorption capacity was examined with the effect of pH and concentration in BSA solution, and adjustment of monomer concentration such as hydrophilic 2-acrylamido-2-methyl-1-propanesulfonic acid and acrylamide in the adsorbent. The effect of hydrophobic butyl methacylate on BSA adsorption was also studied. Selective removal in a bicomponent with BSA and bovine gamma-globulin was performed by adjusting the pH as required.

Kinetics of the Extraction of Succinic Acid with Tri-n-octylamine in 1-Octanol Solution

Kinetic studies for the extraction of succinic acid from aqueous solution with 1‐octanol solutions of tri‐n‐octylamine (TOA) were carried out using a stirred cell with a microporous hydrophobic membrane. The interfacial concentrations of species were correlated and thus the intrinsic kinetics was obtained. The overall extraction process was controlled by the chemical reaction at or near the interface between the aqueous and organic phases. The formation reaction of succinic acid‐TOA complex was found to be first order with respect to the concentration of succinic acid in the aqueous phase and the order of 0.5 with respect to that of TOA in the organic phase with a rate constant of (3.14 ± 0.6) × 10−8 m2.5·mol−0.5·s−1. The dissociation reaction of succinic acid‐TOA complex was found to be the second‐order with respect to that of succinic acid‐TOA complex in the organic phase and the order of –2 with respect to that of TOA in the organic phase with a rate constant of (1.44 ± 1.4) × 10−4 mol·m−2·s−1.

Development of a fully integrated microfluidic system for sensing infectious viral disease

An active micromixer system utilizing the magnetic force was developed and examined for its ability to facilitate the mixing of more than two fluid flows. The mixing performance of the active micromixer was evaluated in aqueous–aqueous systems including dyes for visual observation. A complete analytical microfluidic system was developed by integrating various functional modules into a single chip, thus allowing cell lysis, sample preparation, purification of intracellular molecules, and subsequent analysis. Upon loading the cell samples and lysis solution into the mixing chamber, the integrated microfluidic device allows efficient cell disruption by rotation of a micromagnetic disk and control of mixing time using the Teflon‐coated hydrophobic film as a microvalve. This inflow is followed by separating the cell debris and contaminated proteins from the cell lysate sample using the acrylamide (AAm)‐functionalized SPE. The inflow of partially purified cell lysate sample containing the gold binding polypeptide (GBP)‐fusion protein was bound onto the gold micropatterns by means of its metal binding affinity. The GBP‐fusion method allows immobilization of proteins in bioactive forms onto the gold surface without surface modification suitable for studying antigen–antibody interaction. It was used for the detection of severe acute respiratory syndrome (SARS), an infectious viral disease, as an example case.

Effective extraction of oligomeric proanthocyanidin (OPC) from wild grape seeds

The Oligomeric proanthocyanidin (OPC) in green and black tea, grape seeds, grapes and wine has raised much attention but that OPC in wild grape seed remains to be intensively investigated. This study investigated the total OPC contents and total antioxidant activity of wild grape seeds and developed an efficient extraction process with various temperatures, solvent compositions and times. Also, a chromatography column packed with the Dia-ion HP-20 resin was used for further purification of the OPC. The total OPC contents were determined with the Folin-Ciocalteu reagent, and the antioxidant activity using total antioxidant potential (TAP) and 1,1-diphenyl-2picrylhydrazyl (DPPH). The yield of final purified OPC was 1.78 (+)-catechin equivalent (CE) g/100 g, with IC50 activities of TAP and DPPH of 31.60 and 15.70 μg/mL. These activities of the final purified OPC were about two times higher than that of the BHA used as a reference sample.

Advanced cleanup process of the free-flow microfluidic device for protein analysis.

The treatment of samples preparation is generally recognized as a bottleneck for the rapid analysis of protein because of the off-chip performance in many cases. In this study, we used the charge characteristics of protein to develop a simple and rapid electro-microfluidic desalting system as an effective means of cleaning up protein sample. When we loaded a urea-rich protein sample and a buffer solution into a free-flow zone electrophoresis (FFZE) chamber, the microfluidic device was able to separate the charged protein sample and the non-charged urea. With a 90 V electric field in the FFZE chamber, the removal efficiency of the urea was about 88% and the recovery of the protein was 78%. In addition, the desalted protein sample used in this device showed significant improvement with respect to the MALDI-TOF-MS spectrum signal of a fusion protein, which was fused to the gold-binding polypeptide with enhanced green fluorescent protein, as a model protein. The inflow of the purified fusion protein sample can be successfully immobilized on the gold surface and analyzed by confocal fluorescence microscopy and surface plasmon resonance for biotechnological sensors.

Predispersed solvent extraction of succinic acid aqueous solution by colloidal liquid aphrons in column

A study of the PDSE (predispersed solvent extraction) for succinic acid by colloidal liquid aphrons was conducted. The organic phase contaning TOA (tri-n-octylamine) and 1-octanol permits a selective extraction of succinic acid from its aqueous solution. There was no difference of the extractability of PDSE and that of conventional mixer-settler type extraction. Taking into account the no mechanical mixing in PDSE, it was concluded that the PDSE process is more adaptive than the conventional mixer-settler type extraction process. From mass transfer analysis at the various concentration of TOA in counter-current continuous operation, the concentration of TOA had no influence on the mass transfer coefficient. The loading values in continuous PDSE were almost same as those in batch operation.

Clean up protein for analysis from salt-rich sample using facilitated by copper ion in micro-device

In this study, we made the simple and rapid microfluidic desalting systems. They are 3-phase flow micro-dialysis using simple diffusion and 5-phase flow micro-dialysis based on the coupling of simple diffusion and affinity of urea for the effective removal of urea. The facilitative desalting system is particularly useful for removal of urea and analysis of protein by mass spectroscopy because urea is removed by the mass transfer with the difference of concentration, molecular size and the affinity of urea to copper (II) ion resulting the complex. We also evaluated the activity and MALDI-TOF-MS spectrum of red fluorescent protein (RFP) for protein analysis.

Sample Clean-up of Red Fluorescent Protein for Analysis Using Electric Field in Microfluidic Device

Microfluidic technology allows the design and operation of effective and simple devices for sample preparation and cleanup. Majority of current sample preparation methods is focused on the complex and combined steps such as solid phase extraction and membrane dialysis. In addition, it is generally recognized that sample treatment often is the bottleneck for the rapid analysis of protein due to performing off-chip in many cases. In this study, for an effective cleaning of protein from a urea-rich protein sample, electro-microfluidic desalting system was applied using the charge characteristics of protein.