Optimization of leucrose production by dextransucrase from <i>Streptococcus mutans</i> and its application as an adipogenesis regulator

Lee, Daeyeon,Lee, Jihye,Hong, Moon-Gi,Lee, Byung-Hoo,Kim, Young-Min,Chang, Pahn-Shick,Kim, Yuri,Yoo, Sang-Ho Elsevier 2017 Journal of Functional Foods Vol.39 No.-

<P><B>Abstract</B></P> <P>Leucrose is a sucrose isomer which has an α-1,5-linkage, and slowly hydrolyzed to glucose and fructose by small intestinal α-glucosidases. Leucrose can be produced by an isomerization reaction of dextransucrase on a sucrose substrate. In this study, the recombinant dextransucrase from <I>Streptococcus mutans</I> (<I>Sm</I>DS) was applied to optimize the reaction conditions for leucrose production. With a substrate mixture of 0.5 M sucrose + 1.0 M fructose, the greatest yield (ca. 24.5%) of leucrose was obtained by <I>Sm</I>DS treatment at 30°C for 120h. When preadipocyte 3T3-L1 cells were treated with leucrose, this disaccharide inhibited intracellular lipid accumulation in a dose-dependent manner and significantly suppressed mRNA levels of major adipogenic genes, including CCAT/enhancer-binding protein α (<I>C/EBPα</I>), peroxisome proliferator-activated receptor-γ (<I>PPARγ</I>), fatty acid synthase (<I>FAS</I>), and sterol regulatory element-binding protein-1C (<I>SREBP-1C</I>). Phosphorylation of PI3 kinase/Akt/mTOR was also reduced with leucrose treatment. These results suggest that leucrose has a potential in regulating adipogenesis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Leucrose was produced by dextransucrase isomerization of on sucrose. </LI> <LI> The production yield of leucrose was about 24.5 ± 3.5% by this enzymatic process. </LI> <LI> Leucrose inhibited the adipogenesis by regulating adipogenic gene expression. </LI> <LI> Leucrose has a potential to serve as a functional sweetener. </LI> </UL> </P>

Uncoordinated tetrazole ligands in metal–organic frameworks for proton‐conductivity studies

Lee Daeyeon,Lee Sangho,Son Younghu,Kim Jun Yeong,Cha Seungheon,Kwak Dongmin,Lee Jooyeon,Kwak Jaesung,Yoon Minyoung,Kim Min 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.7

Zr-based metal–organic frameworks (MOFs) were modified with pendant tetrazole ligands for proton conductivity studies. Although tetrazolate ligands coordinated to metal cations have been widely utilized to construct MOFs or porous coordination polymers, to date, the use of uncoordinated tetrazole groups in MOFs has been limited. In this study, a benzene-1,4-dicarboxylic acid with pendant tetrazole groups (BDC-N4) was synthesized and used to prepare a Zr-based UiO-66 MOF using a mixed-ligand strategy. The tetrazolefunctionalized UiO-66-N4 was compared to MOFs containing other acidic functional groups (hydroxyl, carboxylic acid, and sulfonic acid) with respect to their proton conductivities and acidities (calculated pKa). Interestingly, UiO-66-N4 showed a significant decrease in the activation energy with increase in the amount of added tetrazole groups, suggesting the Grotthuss proton conduction mechanism for uncoordinated tetrazole-containing MOFs.

Enhanced multi-fidelity model for flight simulation using global exploration and the Kriging method

Lee, Daeyeon,Van Nguyen, Nhu,Tyan, Maxim,Chun, Hyung-Geun,Kim, Sangho,Lee, Jae-Woo SAGE Publications 2017 Proceedings of the Institution of Mechanical Engin Vol.231 No.4

Recent developments in scale-up of microfluidic emulsion generation via parallelization

Daeyeon Lee,Heon-Ho Jeong,David Issadore 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.6

Microfluidics affords precise control over the flow of multiphasic fluids in micron-scale channels. By manipulating the viscous and surface tension forces present in multiphasic flows in microfluidic channels, it is possible to produce highly uniform emulsion droplets one at a time. Monodisperse droplets generated based on microfluidics are useful templates for producing uniform microcapsules and microparticles for encapsulation and delivery of active ingredients as well as living cells. Also, droplet microfluidics have been extensively exploited as a means to enable highthroughput biological screening and assays. Despite the promise droplet-based microfluidics hold for a wide range of applications, low production rate (<<10mL/hour) of emulsion droplets has been a major hindrance to widespread utilization at the industrial and commercial scale. Several reports have recently shown that one way to overcome this challenge and enable mass production of microfluidic droplets is to parallelize droplet generation, by incorporating a large number of droplet generation units (N>>100) and networks of fluid channels that distribute fluid to each of these generators onto a single chip. To parallelize droplet generation and, at the same time, maintain high uniformity of emulsion droplets, several considerations have to be made including the design of channel geometries to ensure even distribution of fluids to each droplet generator, methods for large-scale and uniform fabrication of microchannels, device materials for mechanically robust operation to withstand high-pressure injection, and development of commercially feasible fabrication techniques for three-dimensional microfluidic devices. We highlight some of the recent advances in the mass production of highly uniform microfluidics droplets via parallelization and discuss outstanding issues.

Bicontinuous Biphasic Liquid Emulsions from Ternary Fluid Mixtures

Daeyeon Lee(이대연) 한국고분자학회 2023 한국고분자학회 학술대회 연구논문 초록집 Vol.48 No.1

Effect of interaction heterogeneity on colloidal arrangements at a curved oil–water interface

Lee, Mina,Lee, Daeyeon,Park, Bum Jun The Royal Society of Chemistry 2015 SOFT MATTER Vol.11 No.2

<P>We report the unique arrangement behaviour of colloidal particles at a curved oil–water interface. Particles trapped at a centrosymmetrically curved oil–water interface, formed by placing an oil lens at a neat air–water interface, organize into diverse arrangement structures due to electrostatic repulsion under the gravitational field. To reveal a possible mechanism behind the observed diversity, we investigate the interactions between pairs of particles at the curved oil–water interface. The magnitude of electrostatic repulsive interactions between pairs of particles is determined by minimizing the total potential of the particle pairs. We show that the pair interactions are quite heterogeneous, following a Gamma distribution. Using the experimentally determined pair potential and the heterogeneity in the potential as input parameters for Monte Carlo simulations, we show that such interaction heterogeneity affects the particle arrangements at the curved interface and results in an observed diversity in the particle arrangement structures. We believe that this work prompts further experimental and simulation studies to extensively understand hierarchical relations from small scale measurements (<I>e.g.</I>, pair interactions and heterogeneity) to bulk scale properties (<I>e.g.</I>, microstructure and interfacial rheology).</P> <P>Graphic Abstract</P><P>Interaction heterogeneity affects the particle arrangements at the curved oil–water interface, leading to diversity in the arrangement structures. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4sm02068e'> </P>

Effects of Anionic Surfactants on the Water Permeability of a Model Stratum Corneum Lipid Membrane

Lee, Sang-Wook,Tettey, Kwadwo E.,Yarovoy, Yury,Lee, Daeyeon American Chemical Society 2014 Langmuir Vol.30 No.1

<P>The stratum corneum (SC) is the ourtermost layer of the epidermis and has a brick-and-mortar-like structure, in which multilamellar lipid bilayers surround flattened dead cells known as corneocytes. The SC lipid membranes provide the main pathway for the transport of water and other substances through the SC. While the physicochemical properties of the SC can be affected by exogenous materials such as surfactants, little is known about how the water barrier function of the SC lipid membranes is compromised by common surfactants. Here, we study the effect of common anionic surfactants on the water permeability of a model SC lipid membrane using a quartz crystal microbalance with dissipation monitoring (QCM-D). Particularly, the effect of sodium dodecyl sulfate (SDS) and sodium lauryl ether sulfate (SLES) is compared. These two surfactants share commonality in their molecular structure: sulfate in the polar headgroup and the same apolar tail. The mass of the lipid membranes increases after the surfactant treatment at or above the critical micelle concentration (CMC) of the surfactants due to their absorption into the membranes. The incorporation of the surfactants into the lipid membranes is also accompanied by partial dissolution of the lipids from the model SC lipid membranes as confirmed by Fourier-transform infrared (FT-IR) spectroscopy. Although the water sorption of pure SDS is much lower than that of pure SLES, the water sorption of SDS-treated membranes increases significantly similar to that of SLES-treated membranes. By combining QCM-D and FT-IR spectroscopy, we find that the chain conformational order and stiffness of the lipid membranes decrease after SDS treatment, resulting in the increased water sorption and diffusivity. In contrast, the conformational order and stiffness of the SLES-treated lipid membranes increase, suggesting that the increased water sorption capacity of SLES-treated lipid membranes is due to the hygroscopic nature of SLES.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2014/langd5.2014.30.issue-1/la403138a/production/images/medium/la-2013-03138a_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la403138a'>ACS Electronic Supporting Info</A></P>

Factory-on-a-chip: Scaling-up Droplet Microfluidics for Large-scale Materials Synthesis

Daeyeon Lee(이대연) 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2

Taking advantage of the precise control over the fluid flows in microchannels, droplet microfluidics has enjoyed a tremendous success in enabling synthesis of highly uniform and uniquely structured liquid droplets and gas bubbles. Although some successes in translating microfluidic-based assays and diagnostics to commercial technologies have been achieved, few examples of such translations in the domain of materials manufacturing based on microfluidics have been accomplished, largely due to the very low throughput of droplet/bubble generations. Without solving the scale-up challenge, microfluidic-based materials synthesis will continue to remain an academic exercise that may not reach its true potential in transforming various sectors of industry including medicine, personal/home care products, separations and catalysis. In this talk, I will present the recent developments that the Issadore and Lee Groups at the University of Pennsylvania have made in enabling large-scale manufacturing of materials using microfluidics. By parallelizing flow focusing generation units coupled with flow resistors in solvent-resistant materials, microfluidic generation of droplets and bubbles with precisely controlled size and morphology has been achieved at the liters-per-hr scale. Critical issues in enabling scale-up and outstanding challenges in future development of the scale-up devices will be discussed.

Stabilization and fabrication of microbubbles: applications for medical purposes and functional materials

Lee, Mina,Lee, Eun Yeol,Lee, Daeyeon,Park, Bum Jun The Royal Society of Chemistry 2015 SOFT MATTER Vol.11 No.11

<P>Microbubbles with diameters ranging from a few micrometers to tens of micrometers have garnered significant attention in various applications including food processing, water treatment, enhanced oil recovery, surface cleaning, medical purposes, and material preparation fields with versatile functionalities. A variety of techniques have been developed to prepare microbubbles, such as ultrasonication, excimer laser ablation, high shear emulsification, membrane emulsification, an inkjet printing method, electrohydrodynamic atomization, template layer-by-layer deposition, and microfluidics. Generated bubbles should be immediately stabilized <I>via</I> the adsorption of stabilizing materials (<I>e.g.</I>, surfactants, lipids, proteins, and solid particles) onto the gas–liquid interface to lower the interfacial tension. Such adsorption of stabilizers prevents coalescence between the microbubbles and also suppresses gas dissolution and resulting disproportionation caused by the presence of the Laplace overpressure across the gas–liquid interface. Herein, we comprehensively review three important topics of microbubbles: stabilization, fabrication, and applications.</P> <P>Graphic Abstract</P><P>In this review, we discuss the controlled stability of microbubbles, recent developments in a variety of microbubble preparation techniques, and applications of bubbles for medicine and functional materials. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5sm00113g'> </P>

리니어 부싱을 이용한 수직형 추력측정장치 개발에 대한 연구

이대연(DaeYeon Lee),백지웅(Jiwoong Baek),김지운(JiWoon Kim),이민수(MinSoo Lee),고영성(YoungSung Ko) 한국추진공학회 2022 한국추진공학회 학술대회논문집 Vol.2022 No.11