Artificial cellular nano-environment composed of collagen-based nanofilm promotes osteogenic differentiation of mesenchymal stem cells

Hwang, Jun-Ha,Han, Uiyoung,Yang, Miso,Choi, Yonghyun,Choi, Jonghoon,Lee, Jong-Min,Jung, Han-Sung,Hong, Jinkee,Hong, Jeong-Ho Elsevier 2019 ACTA BIOMATERIALIA Vol.86 No.-

<P><B>Abstract</B></P> <P>In regenerative medicine, the generation of therapeutic stem cells and tissue engineering are important for replacing damaged tissues. Numerous studies have attempted to produce cellular components that mimic the native tissue for gaining optimal function. Particularly, the extracellular matrix (ECM) composition plays an important role in cellular functions including determining the fates of mesenchymal stem cells (MSCs). Here, we evaluated the osteogenic effects of a nanofilm in which oppositely charged polyelectrolytes were alternately adsorbed onto the cell surface to create an artificial ECM environment for single MSCs. Interestingly, nanofilm composed of collagen (Col) and alginate (AA) showed relatively high stiffness and MSCs coated with the Col/AA nanofilm showed increased osteogenic differentiation efficiency compared to other nanofilm-coated MSCs. Further analysis revealed that the Col/AA nanofilm coating stimulated osteogenesis by activating transcriptional coactivators with the PDZ binding motif through extracellular signal-related kinase and p38 MAPK signaling. This nano-sized cellular coating will facilitate the development of nanotechnology for controlling cellular functions and advance stem cell-based clinical applications for regenerative medicine.</P> <P><B>State of Significance</B></P> <P>In this study, we developed an artificial cellular nano-environment formed by multilayer nanofilms. We demonstrated that the nanofilms introduced to mesenchymal stem cells (MSCs) stimulate osteogenic differentiation by regulating intracellular signaling. Among the various nanofilm combinations, the induction of osteogenic gene transcription in collagen (Col) and alginate (AA) film-coated MSCs was the most pronounced compared to that on other nanofilms. A minimum number of Col/AA nanofilm bilayers (n = 2) was required for effective induction of MSC osteogenic differentiation. In addition, we observed the correlation between the promoting effect of osteogenic differentiation and stiffness of the nanofilm. Our results may be useful for developing a cell coating model system widely applicable in bioengineering and regenerative medicine.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Optical and Magnetic Properties of Copper Doped Zinc Oxide Nanofilms

Shifeng Zhao,Yulong Bai,Jieyu Chen,Alima Bai,Wei Gao 한국자기학회 2014 Journal of Magnetics Vol.19 No.1

Copper doped Zinc Oxide nanofilms were prepared using a simple and low cost wet chemical method. The microstructures, phase structure, Raman shift and optical absorption spectrum as well as magnetization were investigated for the nanofilms. Room temperature ferromagnetism has been observed for the nanofilms. Structural analyses indicated that the films possess wurtzite structure and there are no segregated clusters of impurity phase appreciating. The results show that the ferromagnetism in Copper doped Zinc Oxide nanofilms is driven either by a carrier or defect-mediated mechanism. The present work provides an evidence for the origin of ferromagnetism on Copper doped Zinc Oxide nanofilms.

Fluorescence Modulation of Graphene Quantum Dots Near Structured Silver Nanofilms

Chae, Weon-Sik,Yun, Jungheum,Nam, Sang-Hyeon,Lee, Sang-Geul,Yang, Won-Geun,Yoon, Hyewon,Park, Minsu,Jeon, Seokwoo American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.16

<P>Here, we study the plasmonic metal-enhanced fluorescence properties of blue-emitting graphene quantum dots (GQDs) and green-emitting graphene oxide quantum dots (GOQDs) using fluorescence lifetime imaging microscopy. Reactive ion sputtered silver (Ag) on zinc oxide (ZnO) thin films deposited on silicon (Si) wafers are used as the substrates. The morphology of the sputtered Ag gradually changes from nanoislands, via and elongated network and a continuous film with nanoholes, to a continuous film with increasing sputtering time. The fluorescence properties of GQD and GOQD on the Ag are modulated in terms of the intensities and lifetimes as the morphology of the Ag layers changes. Although both GQD and GOQD show similar fluorescence modulation on the Ag nanofilms, the fluorescence of GQD is enhanced, whereas that of GOQD is quenched due to the charge transfer process from GOQD to ZnO. Moreover, the GQD and GOQD exhibit different fluorescence lifetimes due to the effect of their electronic configurations. The theoretical calculation explains that the fluorescence amplification on the Ag nanofilms can largely be attributed to the enhanced absorption mechanism arising from accumulated optical fields around nanogaps and nanovoids in the Ag nanofilms.</P> [FIG OMISSION]</BR>

제일원리 계산을 통한 두께 변화에 따른 산화 아연 나노 박막의 압전 효과 해석 및 유한요소법으로의 응용

임진명(Jin-Myoung Lim),조경재(Kyeongjae Cho),조맹효(Maenghyo Cho) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10

Nano-structured piezoelectric materials, with their unique electromechanical coupled properties, have enabled the successful design and operation of a wide range of nano-sensors and -actuators. The size dependent piezoelectricity of ZnO nanofilms is investigated through First-principles calculations. Piezoelectric tensor is calculated, whose calculation scheme is based on Berry phase theory. Nanofilms ranging from 0.27 to 1.8 nm in thickness are modeled quantum mechanically. A three-dimensional finite element model is developed to accurately predict the complete electromechanical properties in piezoelectric nanofilms with thickness changes. The effective piezoelectric constant of ZnO nanofilms has inclination to converge monotonically that of bulk ZnO, and the thickness effect of piezoelectric nanofilms is represented.

Inkjet-based multilayered growth factor-releasing nanofilms for enhancing proliferation of mesenchymal stem cells in vitro

Choi, M.,Choi, D.,Han, U.,Hong, J. THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2017 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.50 No.-

<P>We report the preparation and characterization of inkjet-based basic fibroblast growth factor (bFGF)containing nanofilms on a flexible PET substrate. bFGF and heparin (HEP) were assembled by inkjet-based layer-by-layer (LbL) assembly driven by electrostatic interactions. The bFGF/HEP nano-assembly surface coatings were formed via alternating printing adsorption of positively charged bFGF and negatively charged HEP; the process was monitored by UV-vis spectroscopy and quartz crystal microbalance. The bFGF release profile could be controlled by altering the number of layers of printed LbL films. Mesenchymal stem cells, which are capable of extended proliferation in vitro, require a continuous supply of bFGF for proliferation. However, enhancing mesenchymal stem cell proliferation by continuous supplying bFGF is difficult, even with medium replacement, because of the instability of bFGF. Here, we established a novel system for releasing bioactive bFGF from a modified surface by using an inkjet-based nanofilm fabrication method. (C) 2017 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.</P>

Inkjet-based multilayered growth factor-releasing nanofilms for enhancing proliferation of mesenchymal stem cells in vitro

최문현,최다희,한의영,홍진기 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.50 No.-

We report the preparation and characterization of inkjet-based basicfibroblast growth factor (bFGF)-containing nanofilms on aflexible PET substrate. bFGF and heparin (HEP) were assembled by inkjet-basedlayer-by-layer (LbL) assembly driven by electrostatic interactions. The bFGF/HEP nano-assembly surfacecoatings were formed via alternating printing adsorption of positively charged bFGF and negativelycharged HEP; the process was monitored by UV–vis spectroscopy and quartz crystal microbalance. ThebFGF release profile could be controlled by altering the number of layers of printed LbLfilms. Mesenchymal stem cells, which are capable of extended proliferation in vitro, require a continuous supplyof bFGF for proliferation. However, enhancing mesenchymal stem cell proliferation by continuoussupplying bFGF is difficult, even with medium replacement, because of the instability of bFGF. Here, weestablished a novel system for releasing bioactive bFGF from a modified surface by using an inkjet-basednanofilm fabrication method.

Nanotechnology, Big things from a Tiny World: a Review

Debnath Bhattacharyya,Shashank Singh,Niraj Satnalika,Ankesh Khandelwal,Seung-Hwan Jeon 보안공학연구지원센터(IJUNESST) 2009 International Journal of u- and e- Service, Scienc Vol.2 No.3

Photocatalytic degradation performance of various types of modified TiO₂ against nitrophenols in aqueous systems

Fatima, Rida,Afridi, Muhammad Naveed,Kumar, Vanish,Lee, Jechan,Ali, Imran,Kim, Ki-Hyun,Kim, Jong-Oh Elsevier 2019 JOURNAL OF CLEANER PRODUCTION Vol.231 No.-

<P><B>Abstract</B></P> <P>Nitrophenols are used extensively in the chemical, pharmaceutical, and pesticide industries. Recently, water pollution caused by nitrophenols has gained worldwide attention. Significant efforts have been made over the past years to develop effective treatment options for the removal of nitrophenols in aqueous phase. Photocatalysis using titanium dioxide (TiO<SUB>2</SUB>) is regarded as one of the most effective options to degrade nitrophenols in contaminated water. This review deals with the performance of TiO<SUB>2</SUB> photocatalysis for the degradation of nitrophenols and related mechanisms. The performance of TiO<SUB>2</SUB> photocatalysts is assessed by comparing basic performance metrics such as quantum yields and reaction rates before and after modification (e.g., pristine vs. modified forms). Results suggest that TiO<SUB>2</SUB>-based photocatalysis is a promising treatment option for degrading nitrophenol.</P>

Synthesis and Characterization of Functional Nanofilm-Coated Live Immune Cells

Hwang, Jangsun,Choi, Daheui,Choi, Moonhyun,Seo, Youngmin,Son, Jaewoo,Hong, Jinkee,Choi, Jonghoon American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.21

<P>Layer-by-layer (LbL) assembly techniques have been extensively studied in cell biology because of their simplicity of preparation and versatility. The applications of the LbL platform technology using polysaccharides, silicon, and graphene have been investigated. However, the applications of the above-mentioned technology using living cells remain to be fully understood. This study demonstrates a living cell-based LbL platform using various types of living cells. In addition, it confirms that the surplus charge on the outer surface of the coated cells can be used to bind the target protein. We develop a living cell-based LbL platform technology by stacking layers of hyaluronic acid (HA) and poly-<SMALL>L</SMALL>-lysine (PLL). The HA/PLL stacking results in three bilayers with a thickness of 4 ± 1 nm on the cell surface. Furthermore, the multilayer nanofilms on the cells are completely degraded after 3 days of the application of the LbL method. We also evaluate and visualize three bilayers of the nanofilm on adherent (AML-12 cells)-, nonadherent (trypsin-treated AML-12 cells)-, and circulation type [peripheral blood mononuclear cells (PBMCs)] cells by analyzing the zeta potential, cell viability, and imaging via scanning electron microscopy and confocal microscopy. Finally, we study the cytotoxicity of the nanofilm and characteristic functions of the immune cells after the nanofilm coating. The multilayer nanofilms are not acutely cytotoxic and did not inhibit the immune response of the PBMCs against stimulant. We conclude that a two bilayer nanofilm would be ideal for further study in any cell type. The living cell-based LbL platform is expected to be useful for a variety of applications in cell biology.</P> [FIG OMISSION]</BR>

Plasmonic and passivation effects of Au decorated RGO@CdSe nanofilm uplifted by CdSe@ZnO nanorods with photoelectrochemical enhancement

Zhang, Zhuo,Choi, Mingi,Baek, Minki,Deng, Zexiang,Yong, Kijung Elsevier 2016 Nano energy Vol.21 No.-

<P><B>Abstract</B></P> <P>Here, we demonstrate that the photoactivity of gold (Au)-decorated two-story hetero-nanostructures for photoelectrochemical (PEC) efficiency can be effectively enhanced by the plasmonic effect between Au and semiconductors in the visible region and by the passivation effect in the UV region. An Au-decorated two-story hetero-nanostructure was prepared as follows. The upper story is a novel hetero-nanofilm consisting of a reduced graphene oxide (RGO) nanofilm covered by a large area of crystalline CdSe nanolayer with a (111) plane outside and a thickness less than 8nm; the bottom story consists of CdSe-coated ZnO hetero-nanorods. In the visible region, the plasmonic effects between Au and other materials, such as ZnO, CdSe and RGO, were analyzed separately by reassembling the component ZnO nanorods, the CdSe layer and the RGO nanofilm. The photoconversion of the two-story hetero-nanostructure can be improved via the plasmonic effects between Au and n-type semiconductors, such as ZnO and CdSe, due to the stronger Schottky rectifier effects and hot-electron injection. In the UV light region, the photoconversion can be dramatically enhanced via the passivation of surface trap states. Moreover, the electron lifetime of the two-story hetero-nanostructure can also be improved by the suppression of electron–hole recombination by the Au nanoparticles and RGO nanofilms. Overall, CdSe-covered RGO hetero-nanofilms can increase the PEC efficiency 22.42 times over that of bare ZnO, while combination of the plasmonic and passivation effects can further improve this value by 20.7%, illustrating the potential of the two-story hetero-nanostructure in future photoelectrodes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The upper story is a hetero-nanofilm consisting of RGO covered by CdSe nanolayer less than 8 nm. </LI> <LI> The bottom story consists of CdSe-coated ZnO hetero-nanorods. </LI> <LI> In the visible region, photoconversion can be improved via plasmonic effects and Schottky contact. </LI> <LI> In the UV region, photoconversion can be enhanced via the passivation of surface trap states. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>