Hydrogel-based three-dimensional cell culture for organ-on-a-chip applications

Lee, S. H.,Shim, K. Y.,Kim, B.,Sung, J. H. American Institute of Chemical Engineers 2017 Biotechnology progress Vol.33 No.3

<P>Recent studies have reported that three-dimensionally cultured cells have more physiologically relevant functions than two-dimensionally cultured cells. Cells are three-dimensionally surrounded by the extracellular matrix (ECM) in complex in vivo microenvironments and interact with the ECM and neighboring cells. Therefore, replicating the ECM environment is key to the successful cell culture models. Various natural and synthetic hydrogels have been used to mimic ECM environments based on their physical, chemical, and biological characteristics, such as biocompatibility, biodegradability, and biochemical functional groups. Because of these characteristics, hydrogels have been combined with microtechnologies and used in organ-on-a-chip applications to more closely recapitulate the in vivo microenvironment. Therefore, appropriate hydrogels should be selected depending on the cell types and applications. The porosity of the selected hydrogel should be controlled to facilitate the movement of nutrients and oxygen. In this review, we describe various types of hydrogels, external stimulation-based gelation of hydrogels, and control of their porosity. Then, we introduce applications of hydrogels for organ-on-a-chip. Last, we also discuss the challenges of hydrogel-based three-dimensional cell culture techniques and propose future directions. (C) 2017 American Institute of Chemical Engineers.</P>

Cell-free translational screening of an expression sequence tag library of Clonorchis sinensis for novel antigen discovery

Kasi, D.,Catherine, C.,Lee, S. W.,Lee, K. H.,Kim, Y. J.,Ro Lee, M.,Ju, J. W.,Kim, D. M. American Institute of Chemical Engineers 2017 Biotechnology progress Vol.33 No.3

<P>The rapidly evolving cloning and sequencing technologies have enabled understanding of genomic structure of parasite genomes, opening up new ways of combatting parasite-related diseases. To make the most of the exponentially accumulating genomic data, however, it is crucial to analyze the proteins encoded by these genomic sequences. In this study, we adopted an engineered cell-free protein synthesis system for large-scale expression screening of an expression sequence tag (EST) library of Clonorchis sinensis to identify potential antigens that can be used for diagnosis and treatment of clonorchiasis. To allow high-throughput expression and identification of individual genes comprising the library, a cell-free synthesis reaction was designed such that both the template DNA and the expressed proteins were co-immobilized on the same microbeads, leading to microbead-based linkage of the genotype and phenotype. This reaction configuration allowed streamlined expression, recovery, and analysis of proteins. This approach enabled us to identify 21 antigenic proteins. (C) 2017 American Institute of Chemical Engineers</P>

Permeability enhancement of Escherichia coli by single-walled carbon nanotube treatment

Mosleh, A.,Heintz, A.,Lim, K. T.,Kim, J. W.,Beitle, R. American Institute of Chemical Engineers 2017 Biotechnology progress Vol.33 No.3

<P>This research investigated the use of single-walled carbon nanotubes (SWNTs) as an additive to increase the permeability of a bacterial cell wall. Recombinant Escherichia coli BL21 (DE3) that expressed beta-lactamase were exposed to SWNTs under various levels of concentration and agitation. Activity of beta-lactamase in the culture fluid and transmission electron microscopy (TEM) were used to determine the amount of released protein, and visually examine the permeability enhancement of the cells. It was found that beta-lactamase release in the culture fluid occurred in a dose-dependent manner with treatment by SWNTs and was also dependent on agitation rate. Based on TEM, this treatment successfully caused an increase in permeability without significant damage to the cell wall. Consequently, SWNTs can be used as an enhancement agent to cause the release of intracellular proteins. (C) 2017 American Institute of Chemical Engineers</P>

Environmental and economic analysis of a water network system using LCA and LCC

Lim, Seong‐,Rin,Park, Jong Moon American Institute of Chemical Engineers 2007 AIChE Journal Vol.53 No.12

<P><B>Abstract</B></P><P>Water network synthesis has been used to conserve water resources and reduce costs. The objective of this study was to verify the higher eco‐efficiency of a water network system (WNS), and to identify principal contributors to environmental burdens and economic costs using life cycle assessment (LCA) and life cycle costing (LCC). The WNS was compared to the conventional water system (CWS). LCA and LCC results showed that the total environmental burdens and life cycle cost of the WNS were lower than those of the CWS. The consumptions of industrial and ionized water were principal contributors to the environmental and economic burdens. The third principal contributor to the environmental burdens was electricity consumption, but that to the economic costs was piping cost. These principal contributors can be employed to obtain the simple and practical mathematical optimization models synthesizing the most environmentally friendly, economical, or sustainable WNSs. © 2007 American Institute of Chemical Engineers AIChE J, 2007</P>

The development of a thermostable CiP (Coprinus cinereus peroxidase) through in silico design.

Kim, Su Jin,Lee, Jeong Ah,Joo, Jeong Chan,Yoo, Young Je,Kim, Yong Hwan,Song, Bong Keun American Institute of Chemical Engineers ; America 2010 Biotechnology progress Vol.26 No.4

<P>Protein thermostability is a crucial issue in the practical application of enzymes, such as inorganic synthesis and enzymatic polymerization of phenol derivatives. Much attention has been focused on the enhancement and numerous successes have been achieved through protein engineering methods. Despite fruitful results based on random mutagenesis, it was still necessary to develop a novel strategy that can reduce the time and effort involved in this process. In this study, a rapid and effective strategy is described for increasing the thermal stability of a protein. Instead of random mutagenesis, a rational strategy was adopted to theoretically stabilize the thermo labile residues of a protein using computational methods. Protein residues with high flexibility can be thermo labile due to their large range of movement. Here, residue B factor values were used to identify putatively thermo labile residues and the RosettaDesign program was applied to search for stable sequences. Coprinus cinereus (CiP) heme peroxidase was selected as a model protein for its importance in commercial applications, such as the polymerization of phenolic compounds. Eleven CiP residues with the highest B factor values were chosen as target mutation sites for thermostabilization, and then redesigned using RosettaDesign to identify sequences. Eight mutants based on the redesigns, were produced as functional enzymes and two of these (S323Y and E328D) showed increased thermal stability over the wild-type in addition to conserved catalytic activity. Thus, this strategy can be used as a rapid and effective in silico design tool for obtaining thermostable proteins. (c) 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010.</P>

pH‐responsive hydrogel microparticles as intelligent delivery carriers for α‐MSH antagonists

Yang, Juseung,Cho, Geundo,Lee, Tai‐,Gyu,Kim, Bumsang American Institute of Chemical Engineers 2011 AIChE Journal Vol.57 No.7

<P><B>Abstract</B></P><P>For a first step in the development of an intelligent delivery system for a nonapeptide as an α‐MSH antagonist, pH‐responsive P(MAA‐co‐EGMA) hydrogel microparticles were prepared and their feasibility as intelligent delivery carriers was evaluated. There was a drastic change in the swelling ratio of P(MAA‐co‐EGMA) microparticles at a pH of around 5 and as the MAA amount in the hydrogel increased, the swelling ratio increased at a pH above 5. The loading efficiency of the nonapeptide at pH 7 increased with the amount of Methacrylic acid (MAA) in the hydrogel and at pH 2, where the electrostatic attraction was greatest, a high loading efficiency was not obtained because of the low swelling ratio of the hydrogel. The P(MAA‐co‐EGMA) microparticles demonstrated a pH‐sensitive release behavior for the nonapeptide. In addition, the P(MAA‐co‐EGMA) microparticles showed a protective ability for the nonapeptide and preserved the stability of the nonapeptide. © 2010 American Institute of Chemical Engineers AIChE J, 2010</P>

Optimal design of batch‐storage network considering exchange rates and taxes

Yi, Gyeongbeom,Reklaitis, Gintaras V. American Institute of Chemical Engineers 2007 AIChE Journal Vol.53 No.5

<P><B>Abstract</B></P><P>This article presents an integrated analysis of the supply chain and financing decisions of multinational corporations. We construct a model in which multiple currency storage units are installed to manage the currency flows associated with multinational supply chain activities such as raw material procurement, processing, inventory control, transportation, and finished product sales. Temporary financial investments, bank loans, and currency transfer between multiple nations are allowed to increase the marginal profit. The core contribution of this study is its quantitative investigation of the influence of macroscopic economic factors such as exchange rates and taxes on operational decisions. The supply chain is modeled as a batch‐storage network with recycling streams. The objective function of the optimization involves minimizing the opportunity costs of annualized capital investments and currency/material inventories minus the benefit to stockholders in the numeraire currency. The major constraints of the optimization are that the material and currency storage units must not be depleted. A production and inventory analysis formulation (the periodic square wave model) provides useful expressions for the upper and lower bounds and average levels of the currency and material inventory holdings. The expressions for the Kuhn‐Tucker conditions of the optimization problem are reduced to a subproblem and analytical lot‐sizing equations. The lot sizes of procurement, production, transportation, and financial transaction can be determined by analytical expressions once the average flow rates are known. We show that the optimal production lot and storage sizes are typically 20% smaller when corporate income tax is taken into consideration than when it is not considered. An illustrative example is presented to demonstrate the potential of this approach. © 2007 American Institute of Chemical Engineers AIChE J, 2007</P>

Cell-free synthesis and multifold screening of Candida antarctica lipase B (CalB) variants after combinatorial mutagenesis of hot spots.

Park, Chang-Gil,Kwon, Min-A,Song, Jae-Kwang,Kim, Dong-Myung American Institute of Chemical Engineers ; America 2011 Biotechnology progress Vol.27 No.1

<P>We have developed a strategy for rapid and combinatorial optimization of the hot spot residues of enzymes. After combinatorial randomization of target locations in the Candida antarctica lipase B (CalB) gene, the individual variant genes isolated in the E.coli cells were expressed in the cell-free protein synthesis system to analyze different parameters of the resulting CalB variants. The enzymatic assays for the hydrolysis of para-nitrophenyl-ester (pNP-ester) and triglyceride, synthesis of wax ester, and thermal stability of the variant enzymes were carried out simultaneously in 96-well microtiter plates. From the 1,000 variant genes tested in each assay, we were able to identify a series of the variant enzymes having markedly improved hydrolytic, synthetic activity, or thermal stability. The improved traits of the cell-free selected CalB variants were well reproduced when the corresponding genes were expressed in Pichia pastoris. Therefore, we expect that the proposed strategy of cell-free expression screening can serve as a viable option for rapid and precise tuning of enzyme molecules, not only for analytical purposes but also for industrial applications through large scale production using microbial cells transformed with variant genes selected from the cell-free expression screening. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2011.</P>

Production of ethylene glycol from xylose by metabolically engineered <i>Escherichia coli</i>

Chae, Tong Un,Choi, So Young,Ryu, Jae Yong,Lee, Sang Yup American Institute of Chemical Engineers 2018 AIChE Journal Vol.64 No.12

<P>Ethylene glycol (EG) is an important chemical used for several industrial applications including poly(ethylene terephthalate) synthesis. In this study, <I>Escherichia coli</I> was metabolically engineered to efficiently produce EG from xylose. To biosynthesize EG, the Dahms pathway was introduced by expressing <I>xylBC</I> genes from <I>Caulobacter crescentus</I> (<I>xylBC</I><SUB><I>ccs</I></SUB>). Various <I>E. coli</I> strains and glycolaldehyde reductases were screened to find <I>E. coli</I> W3110 strain and glycolaldehyde reductase (<I>yqhD</I>) as optimal combination for EG production. <I>In silico</I> genome‐scale metabolic simulation suggested that increasing the native xylose pathway flux, in the presence of the overexpressed Dahms pathway, is beneficial for EG production. This was achieved by reducing the Dahms pathway flux by employing a synthetic small regulatory RNA targeting <I>xylB</I><SUB><I>ccs</I></SUB>. Fed‐batch culture of the final engineered <I>E. coli</I> strain produced 108.2 g/L of EG in a xylose minimal medium. The yield on xylose and EG productivity were 0.36 g/g (0.87 mol/mol) and 2.25 g/L/h, respectively. © 2018 American Institute of Chemical Engineers <I>AIChE J</I>, 64: 4193–4200, 2018</P>

Amylosucrase-mediated β-carotene encapsulation in amylose microparticles

Letona, Carlos Andres Morales,Park, Cheon-Seok,Kim, Young-Rok American Institute of Chemical Engineers 2017 Biotechnology progress Vol.33 No.6

<P>The -carotene embedded amylose microparticles (BC-AmMPs) were prepared in one-step by utilizing the unique catalytic activity of amylosucrase from Deinococcus geothermalis (DgAS), which synthesizes linear amylose chains using sucrose as the sole substrate. Synthesized amylose chains self-assembled with -carotene to form well-defined spherical microparticles with an encapsulation yield of 65%. The BC-AmMPs produced (average diameter approximate to 8 mu m) were bright orange due to the embedded -carotene, and this was confirmed by Raman analysis. XRD showed BC-AmMPs had a B-type amylose crystal structure with a degree of crystallinity lower than that of AmMPs. This lower crystallinity of AmMP after BC encapsulation was confirmed by DSC analysis. Decreased enthalpy of gelatinization (H-gel) of BC-AmMP implied that molecular order within the amylose microstructure was influenced by the presence of BC. The stability of BC against environmental stresses, such as UV light and oxidative stress, was significantly enhanced by its encapsulation. The authors propose a new approach to the preparation of an amylose based carrier system for active compounds or expensive food ingredients with poor stabilities during storage or processing. Given that amylose is a safe food material, the devised encapsulation system will find wide range of practical applications in the food industry. (c) 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1640-1646, 2017</P>