RGD-Conjugated In Situ Forming Hydrogels as Cell-Adhesive Injectable Scaffolds

Ngoc Quyen Tran,정윤기,Eugene Lih,박경민,박기동 한국고분자학회 2011 Macromolecular Research Vol.19 No.3

In this study, a bioactive hydrogel was prepared from a chitosan derivative and Arg-Gly-Asp (RGD)-conjugated polypseudorotaxane, which is a cell-adhesive extracellular matrix. Chitosan was modified with 4-hydroxy phenyl acetic acid to obtain a water-soluble product for enzymatic cross-linking. Tyramine-terminated polypseudorotaxane (PRx) was prepared from the inclusion complex of a tyramine-terminated poly(ethylene glycol) backbone,and α-cyclodextrin (α-CD). Gly-Arg-Gly-Asp-Ser (GRGDS) was conjugated to the PRx using 4-nitrophenyl chloroformate (NPC) and partially carboxylated with succinic anhydride. The structure of the PRx-RGD and 4-hydroxylphenylacetamide chitosan (CHPA) was characterized by ^1H NMR and FTIR spectroscopy. The RGD content in PRx-RGD was determined to be 0.19%. PRx-RGD and CHPA solution was crosslinked to form a bioactive hydrogel in the presence of horseradish peroxidase (HRP) and hydrogen peroxide (H_2O_2), which exhibited rapid gelation (~20sec). An in vitro cell culture was carried out with L929 mouse fibroblasts for 1 and 3 days. The results showed that fibroblasts adhered better and appeared to be more biocompatible on the RGD-conjugated hydrogel than the hydrogel without RGD. The combined results highlight the potential use of this bioactive hydrogel as an injectable scaffold in tissue engineering applications.

The manufacturing of sintered bricks from clay and red mud derived from the alumina processing plant

Ngoc Tuyen Tran,Duc Vu Quyen Nguyen,Van Minh Hai Ho,Xuan Tin Dang,Ngoc Quang Tran 한양대학교 청정에너지연구소 2017 Journal of Ceramic Processing Research Vol.18 No.5

In this study, the manufacturing of sintered bricks from clay and red mud was presented. The initial materials and obtainedbricks were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope(TEM), X-ray fluorescence (XRF), and differential scanning calorimetry-thermal gravimetry (DSC-TG). The compressivestrength, water absorption, bulk density and sintering shrinkage of sintered bricks were performed. The effects of componentsof raw materials, sintering temperature and time on physico-mechanical properties of the products was investigated. Theresults showed that the bricks prepared at 1000 oC for 1 hr with raw material containing up to 50% of red mud providedexcellent physico-mechanical properties. The obtained brick met the Vietnam standard VS1451-1998 and was satisfied theconstruction material requirements that were safe to human’s health and friendly with environment in terms of alkalineleaching and radioactivity indexes.

In Situ Forming and Rutin-Releasing Chitosan Hydrogels As Injectable Dressings for Dermal Wound Healing

Tran, Ngoc Quyen,Joung, Yoon Ki,Lih, Eugene,Park, Ki Dong American Chemical Society 2011 Biomacromolecules Vol.12 No.8

<P>An in situ gel-forming system composed of rutin- and tyramine-conjugated chitosan derivatives, horseradish peroxidase (HRP), and hydrogen peroxide (H<SUB>2</SUB>O<SUB>2</SUB>) was prepared and applied to dermal wound repair. Rutin was employed to enhance production and accumulation of extracellular matrix in the healing process. In vitro study demonstrates that released rutin significantly enhanced cell proliferation as compared with media without rutin. In vivo wound healing study was performed by injecting hydrogels on rat dorsal wounds with a diameter of 8 mm for 14 days. Histological results demonstrated that rutin-conjugated hydrogel exhibited enhancement of wound healing as compared with treatments with PBS, hydrogel without rutin, and a commercialized wound dressing (Duoderm). More specifically, rutin-conjugated hydrogels induced better defined formation of neo-epithelium and thicker granulation, which is closer to the original epithelial tissue. As a result, this study suggests that the in situ gel-forming system can be a promising injectable gel-type wound dressing.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/bomaf6/2011/bomaf6.2011.12.issue-8/bm200326g/production/images/medium/bm-2011-00326g_0012.gif'></P>

One-Pot Preparation of Antibacterial Electrospun Polycaprolactone Membrane Embedded with Gamma Irradiation-Induced Silver Nanoparticles

Chien Minh Tran,Ngoc Thi‑Thanh Nguyen,Minh Hieu Ho,Vinh Khanh Doan,Khanh Loan Ly,Nhi Ngoc‑Thao Dang,Nam Minh‑Phuong Tran,Hoai Thi‑Thu Nguyen,Long Phuoc Truong,Thai Minh Do,Quyen Ngoc Tran,Hien Quoc Ng 한국섬유공학회 2023 Fibers and polymers Vol.24 No.1

In this study, we proposed a straightforward electrospun polycaprolactone (PCL) loaded with silver nanoparticles (SNPs)membrane fabrication process, in which SNPs were directly synthesized from silver nitrate (AgNO3) in PCL–acetone mixtureby gamma irradiation. The insolubility of AgNO3in PCL solution was solved using an auxiliary dimethyl sulfoxide solvent. As a physical approach, gamma rays readily converted silver ions into SNPs without the addition of harmful reductionagents, which reduced the cytotoxicity of the synthesized material. By avoiding some processes such as purification, solventremoval, or redispersion of SNPs, this method was more time-saving compared to other related studies. SNPs formation wasconfirmed by both UV–Visible spectrum (UV–Vis) and X-ray diffraction analysis. Scanning electron microscopy (SEM)revealed that the addition of SNPs significantly reduced the fiber diameter of PCL–Ag membranes compared to that of rawPCL. Uniform spherical-shaped SNPs incorporated in PCL fibers were observed under transmission electron microscopy(TEM). The tensile test showed that the electrospun PCL–Ag membranes exhibited good mechanical characteristics. Moistureeasily penetrated the porous microstructure of PCL–Ag, facilitating wound humidity regulation. Inductively coupledplasma-mass spectroscopy (ICP-MS) was employed to study the release profiles of SNPs at different time intervals. Overall,the PCL–Ag 500 ppm sample exerted excellent antibacterial activity against Pseudomonas aeruginosa and Staphylococcusaureus strains and low in vitro cytotoxicity.

Application of Total Quality Management in Developing Quality Assessment Model: The Case of Vietnamese Higher Education

Quyen Le Hoang Thuy To NGUYEN,Du Van NGUYEN,Ngoc Nguyen Mong CHU,Van Hong TRAN 한국유통과학회 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.11

The shift from elite education to mass education in Vietnam has met the demand for education for everybody as well as for quality human resource talent for an emerging nation. Under the resource constraint, understanding the quality dimensions of education and its priority level is important for effective and efficient policies. This study was carried out using both qualitative and quantitative methodologies to develop quality criteria and a ranking model. Two rounds of in-depth interviews were conducted with fifteen experts in the field, who were rectors, employers, and recruitment specialists to develop the quality framework applied in Vietnamese universities under total quality management (TQM), starting from the input of the senior secondary school leavers, through a teaching process to the output. The first round of interviews were unstructured questionnaires designed to explore the main factors in quality assessment model. The second round affirmed the experts’ agreement on the assessment model. Then, fuzzy logic was applied to rank eight criteria in the quality assessment model into priority order: cost, teaching and administrative staff, leadership, curriculum, student-related factors, internationalization, admissions, and campus. The results are critical for identifying the necessary actions to enhance the education quality and to further research on the optimal quality model.

Factors Affecting Financial Independence of Young Adults: An Empirical Study in Vietnam

Lan NGUYEN,Quyen Thi TRINH,Thao Ngoc Minh TRAN 한국유통과학회 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.10

Nowadays, with the constant enhancement in the health of the economy, the average income and living standard have accordingly increased, making the need for financial independence a favorable choice. This research aims to identify the factors affecting the financial independence of young people. The authors implement quantitative analysis, with a set of primary data collected from a survey of 2664 Vietnamese people aged from 18 to 28. The research results demonstrate the considerable impact of monetary, psychological, group-related, and family-related factors on the financial independence of young people. The results of the sample analysis provide adequate evidence to reject the correlative relationship between family and group factors and the financial independence of young people. In addition, there are 3 factors, including demographic factors, monetary factors, and psychological factors, all have varying degrees and directions of influence on young people’s financial independence. Most of the mentioned variables reflect a positive effect on financial independence. The only exception is the education variable, illustrated by its negative standardized beta value. A significant difference in financial independence between genders also is reported, suggesting that males seem to have a higher level of financial independence than females.

Self-Assembled Nanogel of Pluronic-Conjugated Heparin as a Versatile Drug Nanocarrier

최종훈,정윤기,배진우,최장원,Tran Ngoc Quyen,박기동 한국고분자학회 2011 Macromolecular Research Vol.19 No.2

Heparin has not been used as a macromolecule to prepare nanocarriers for drug delivery, even though it has advantageous structural features, such as a negatively charged structure and presence of specific binding domains of proteins. In this study, a nanogel of a Pluronic-conjugated heparin was prepared by direct dissolution to develop a versatile drug nanocarrier composed of heparin. The aqueous nanogel solution of the heparin-Pluronic (HP) conjugate, exhibited higher stability than the micelles and smaller hydrodynamic size than 100 nm. The drug encapsulation test demonstrated that the HP nanogel encapsulates efficiently both hydrophobic small molecules and proteins. The release profile of indomethacin (IMC) was almost zero-order without a burst due to the presence of heparin, which appears to be advantageous comparing to polymeric micelles. Circular dichroism (CD) and gel electrophoresis demonstrated that the stability of monoclonal antibodies (3D8 scFv) encapsulated into the HP nanogel had been maintained. Overall, the self-assembled HP nanogel may be a versatile and promising nanocarrier for a range of drugs in drug delivery applications.

Preparation of Silver Core-Chitosan Shell Nanoparticles Using Catechol-Functionalized Chitosan and Antibacterial Studies

Thanh Son Cu,Ngoc Quyen Tran,Van Du Cao,Cuu Khoa Nguyen 한국고분자학회 2014 Macromolecular Research Vol.22 No.4

In this paper, we report the preparation and stabilization of colloidal silver nanoparticle solution, with theassistance of chitosan dihydroxyphenyl acetamide (CDHPA), or oligochitosan dihydroxyphenyl acetamide (OCDHPA). The structure of the chitosan derivatives were characterized by nuclear magnetic resonance (1H NMR) spectroscopy. The morphology of the synthesized silver core-chitosan shell nanoparticles were observed by transmission electronmicroscopy (TEM) and X-ray diffraction (XRD) techniques, and showed a well-defined core-shell structure of polymer-coated silver nanoparticles (AgNPs). The core-shell NPs exhibited a strong antibacterial activity against E. coliand S. aureus, at a very low concentration of AgNPs (2.5 ppm). Our studies offer a new method for the preparationand protection of silver nanoparticles for antibacterial applications.

The reduced reversible phase transition field of lead–free Bi–based ceramic composites by adding nonergodic relaxor

Dinh, Thi Hinh,Tran, Vu Diem Ngoc,Nguyen, Thi Thao,Hoang, Quyen Thi Ngoc,Han, Hyoung–,Su,Lee, Jae–,Shin Elsevier 2017 CERAMICS INTERNATIONAL Vol.43 No.18

<P><B>Abstract</B></P> <P>This study investigated the microstructure, dielectric, ferroelectric, and strain properties of lead‒free 0.995Bi<SUB>1/2</SUB>(Na<SUB>0.82</SUB>K<SUB>0.18</SUB>)<SUB>1/2</SUB>TiO<SUB>3</SUB>–0.005BaZrO<SUB>3</SUB>/0.98Bi<SUB>1/2</SUB>(Na<SUB>0.78</SUB>K<SUB>0.22</SUB>)<SUB>1/2</SUB>TiO<SUB>3</SUB>–0.02LaFeO<SUB>3</SUB> (BNKT18BZ/BNKT22LF) ceramic composites. We found that the required electric field for trigging the phase transition from ergodic relaxor (ER) to ferroelectric of BNKT18BZ/BNKT22LF ceramic composites can be effectively decreased by adding BNKT18BZ as nonergodic relaxor (NER) with changes of three different stabilized regions and the highest <I>S</I> <SUB>usable</SUB> peak points as a function of the applied electric field. The highest <I>d</I> <SUB>33</SUB> <SUP>*</SUP> value of 690p.m./V was obtained at 4kV/mm for 0.3wt BNKT18BZ fraction ceramic composites. This value was higher than 575 p.m./V of BNKT22LF ceramics under an applied electric field of 5kV/mm.</P>

Barriers to Derivative Accounting Disclosure: The Case of Vietnamese Firms

NGUYEN, Hanh Thi Hong,TRAN, Ngoc Minh,NGUYEN, Quyen Le Hoang Thuy To Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.10

This paper explores the barriers to derivative accounting disclosures in Vietnamese companies and ranks their relative importance for effective and efficient remedies. The Delphi technique was applied to get agreement of panel of experts on the measurement of factors hindering disclosure. Unstructured questionnaires were first sent to twelve experts who had both practical experience and academic knowledge in the field to get ideas on the obstructions to derivatives disclosure. The structured questionnaire was designed to get their agreement on barriers to derivative accounting disclosures. The data analysis with mean, median, mode, standard deviation, and quartile has been implemented to ensure the unanimity. Market-related factors, legislation, accountants' attributes, managers' attributes, information technology and communication, and on-site training were the six major obstacles agreed upon by the experts during their in-depth interviews. Then, these factors were ranked by applying the analytical hierarchy process (AHP). The findings confirmed the priority of information technology and communication, which held the greatest weight. Legislation ranked second, followed by market-related factors and on-site training, which explained the impediments to derivatives disclosure. Managers' and accountants' attributes had the least contribution to the barriers to derivative disclosures. The results have important implications for actions to enhance corporate derivative disclosures in Vietnam.