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Seungjib JEON,Hyun Gi KOH,Mi Rae KIM,Young Jin KIM,Hyejeong HEO,Joon-Chul LEE,Yong Keun CHANG 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
Microalgae are promising resources for producing value-added products due to their rapid growth rate and high lipid content. Among products obtained from microalgae, the eicosapentaenoic acid (EPA) which is health supplement has gained attention because of the limitations on fish oil production. In this study, we optimized cultivation conditions of Nannochloropsis salina for enhancement of EPA production. The optimization process was carried out by response surface methodology (RSM) for studying the interactive effect of temperature and N concentration (NaNO₃) using central composite design. The RSM results showed an optimal level of 1.28 g/L for NaNO₃ and 21 ℃ for temperature, resulting in maximum EPA productivity of 14.4 ㎎/L/day. To understand the effect of optimal conditions on EPA production, we analyzed the lipid compositions and pigment contents. The glycolipids and chlorophyll a were found to be increased under optimal conditions. We also investigated mRNA expression levels of genes involved in EPA synthesis by quantitative real-time PCR and confirmed their positive contribution to EPA production.
Yum, Seungjib,An, Tae Kyu,Wang, Xiaowei,Lee, Wonho,Uddin, Mohammad Afsar,Kim, Yu Jin,Nguyen, Thanh Luan,Xu, Shuhao,Hwang, Sungu,Park, Chan Eon,Woo, Han Young American Chemical Society 2014 Chemistry of materials Vol.26 No.6
<P>We report a series of benzotriazole-based semicrystalline π-conjugated polymers with noncovalent conformational locks for applications in polymer field-effect transistors. The benzotriazole moiety is a versatile electron-deficient building block that offers two chemically functionalizable sites, 2(N) and 5, 6(C) positions, allowing easy modulation of the solution processability and electronic structures of the resulting polymers. Fluorine or alkoxy substituents were introduced to the benzotriazole unit to enhance the molecular ordering through intra- and intermolecular F···S, F···H–C, C–F···π<SUB>F</SUB>, or S···O attractive interactions. The fluorinated polymer (<B>PTBTz-F</B>) showed remarkably enhanced hole mobility (μ<SUB>h</SUB> = 1.9 cm<SUP>2</SUP>/(V·s), on/off ratio = 8 × 10<SUP>7</SUP>) upon thermal annealing at 305 °C, compared to the unsubstituted one (<B>PTBTz</B>) (μ<SUB>h</SUB> = 7.0 × 10<SUP>–3</SUP> cm<SUP>2</SUP>/(V·s), on/off ratio = 3 × 10<SUP>6</SUP>). Alkoxy unit substitution (<B>PTBTz-OR</B>) also improved the carrier mobility up to 0.019 cm<SUP>2</SUP>/(V·s) with an on/off ratio of 4 × 10<SUP>5</SUP>. Fluorine or alkoxy substitution induced tight interchain ordering with edge-on orientation, as confirmed by X-ray diffraction measurements. In particular, fluorinated <B>PTBTz-F</B> showed high thermal stability (<I>T</I><SUB>d</SUB> 453 °C) and the remarkable device characteristics with deep frontier orbital levels.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2014/cmatex.2014.26.issue-6/cm4042346/production/images/medium/cm-2013-042346_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm4042346'>ACS Electronic Supporting Info</A></P>
Yum, Seungjib,An, Tae Kyu,Wang, Xiaowei,Uddin, Mohammad Afsar,Nguyen, Thanh Luan,Xu, Shuhao,Ryu, Hwasook,Kim, Yu Jin,Hwang, Sungu,Park, Chan Eon,Woo, Han Young De Gruyter 2014 Pure and Applied Chemistry Vol.86 No.8
<P><B>Abstract</B></P><P>A series of thienothiophene-benzotriazole-based semicrystalline copolymers,<B>PTTBTz</B>,<B>PTTBTz-F</B>, and<B>PTTBTz-OR</B>, were synthesized by considering chain linearity, planarity and inter-chain packing by virtue of non-covalent attractive interaction. Fluorine and alkoxy substituents were introduced to modulate the intra- and inter-chain coulombic interactions and crystalline ordering. The fluorine and alkoxy-substituted<B>PTTBTz-F</B>and<B>PTTBTz-OR</B>showed pronounced inter-chain packing with edge-on orientation confirmed by UV-vis absorption and X-ray diffraction measurements. The well-resolved diffraction patterns were obtained for<B>PTTBTz-F</B>and<B>PTTBTz-OR</B>, showing (100)∼(500) inter-lamellar scattering peaks (d-spacing, 17∼18 Å) in the out-of-plane direction and a π-π stacking peak (d-spacing, 3.5∼4.1 Å) in the in-plane direction. Organic field effect transistor (OFET) devices were fabricated with a bottom gate and top contact geometry.<B>PTTBTz-F</B>(<I>μ</I><SUB>h</SUB>= 4.49 × 10<SUP>-2</SUP>cm<SUP>2</SUP>V<SUP>-1</SUP>s<SUP>-1</SUP>, on/off ratio = 1.13 × 10<SUP>7</SUP>) and<B>PTTBTz-OR</B>(<I>μ</I><SUB>h</SUB>= 8.39 × 10<SUP>-3</SUP>cm<SUP>2</SUP>V<SUP>-1</SUP>s<SUP>-1</SUP>, on/off ratio = 2.98 × 10<SUP>4</SUP>) showed nearly 3 and 2 orders of magnitude higher hole mobility upon annealing at 305 and 260 °C, with compared to the unsubstituted<B>PTTBTz</B>.</P>
Development of Serum-free Medium for Chinese Hamster Ovary Cell Line Producing Recombinant Protein
Na young HONG,Seungjib JEON,Mi Rae KIM,Hyejeong HEO,Sang Yeop LEE,Yong Jin KIM,Tae-Joon JEON,Joon-Chul LEE 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
Fetal bovine serum (FBS) has been used as an essential supplement in mammalian cell cultures. However, serumcontaining media have some disadvantages such as unclear composition, poor reproducibility and high risk of microbial contaminations. Recently, serum-free media has gained attention due to its uniform ingredients, excellent stability, and reproducibility. In this study, we developed serum-free media for recombinant Chinese hamster ovary (CHO) cells using design of experiments (DoE). Significant factors were selected using plackett-burman design, and the fractional factorial design was used to examine interactive effects of adopted components. In the optimal condition, the rCHO cells successfully showed higher maximum viable cell density up to 29x105 cells/mL on fourth day. Also, the optimization of components concentration was carried out by the response surface methodology for enhancing growth of rCHO cells.