National Institute of Hygiene and Epidemiology NIHE

Thị Trấn Trùng Khánh, Vietnam

National Institute of Hygiene and Epidemiology NIHE

Thị Trấn Trùng Khánh, Vietnam
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Le A.-T.,Hanoi University | Tam L.T.,Hanoi University | Tam P.D.,Hanoi University | Huy P.T.,Hanoi University | And 4 more authors.
Materials Science and Engineering C | Year: 2010

The development of new and simple green chemical methods for synthesizing colloidal solutions of functional nanoparticles is desirable for environment-friendly applications. In the present work, we report a feasible method for synthesizing colloidal solutions of silver nanoparticles (Ag NPs) based on the modified Tollens technique. The Ag NPs were stabilized by using oleic acid as a surfactant and were produced for the first time by the reduction of silver ammonium complex [Ag(NH3)2]+ (aq) by glucose with UV irradiation treatment. A stable and nearly monodisperse aqueous Ag NPs solution with average-sized particles (~ 9-10 nm) was obtained. The Ag NPs exhibited high antibacterial activity against both Gram-negative Escherichia Coli (E. coli) and Gram-positive Staphylococcus aureus bacteria. Electron microscopic images and analyses provided further insights into the interaction and bactericidal mechanism of the Ag NPs. The proposed method of synthesis is an effective way to produce highly bactericidal colloidal solutions for medical, microbiological, and industrial applications. © 2010 Elsevier B.V.


Tam P.D.,Hanoi University | Tuan M.A.,Hanoi University | Huy T.Q.,National Institute of Hygiene and Epidemiology NIHE | Le A.-T.,Hanoi University | Hieu N.V.,Hanoi University
Materials Science and Engineering C | Year: 2010

In this paper, a simple DNA sensor platform was developed for rapid herpes virus detection in real samples. The deoxyribonucleic acid (DNA) sequences of the herpes simplex virus (DNA probe) were directly immobilized on the surface of interdigitated electrodes by electrochemical polymerization along with pyrrole monomers. The potential was scanned from - 0.7 to + 0.6 V, and the scanning rate was 100 mV/s. Fourier transform infrared spectroscopy was employed to verify specific DNA sequence binding and the conducting polymer. The morphology of the conducting polymer doped with DNA strands was characterized using a field emission scanning electron microscope. As-obtained DNA sensor was used to detect the herpes virus DNA in the real samples. The results show that the current DNA sensors detected the lowest DNA concentration of 2 nM. This sensitivity appears to be better than that of the DNA sensors prepared by immobilization of the DNA probe on the 3-aminopropyl-triethoxy-silance (APTS) membrane. © 2010 Elsevier B.V.


Anh D.D.,National Institute of Hygiene and Epidemiology NIHE | Lopez A.L.,Korean International Vaccine Institute | Thiem V.D.,National Institute of Hygiene and Epidemiology NIHE | Grahek S.L.,Korean International Vaccine Institute | And 6 more authors.
PLoS Neglected Tropical Diseases | Year: 2011

Background: Killed oral cholera vaccines (OCVs) are available but not used routinely for cholera control except in Vietnam, which produces its own vaccine. In 2007-2008, unprecedented cholera outbreaks occurred in the capital, Hanoi, prompting immunization in two districts. In an outbreak investigation, we assessed the effectiveness of killed OCV use after a cholera outbreak began. Methodology/Principal Findings: From 16 to 28 January 2008, vaccination campaigns with the Vietnamese killed OCV were held in two districts of Hanoi. No cholera cases were detected from 5 February to 4 March 2008, after which cases were again identified. Beginning 8 April 2008, residents of four districts of Hanoi admitted to one of five hospitals for acute diarrhea with onset after 5 March 2008 were recruited for a matched, hospital-based, case-control outbreak investigation. Cases were matched by hospital, admission date, district, gender, and age to controls admitted for non-diarrheal conditions. Subjects from the two vaccinated districts were evaluated to determine vaccine effectiveness. 54 case-control pairs from the vaccinated districts were included in the analysis. There were 8 (15%) and 16 (30%) vaccine recipients among cases and controls, respectively. The vaccine was 76% protective against cholera in this setting (95% CI 5% to 94%, P = 0.042) after adjusting for intake of dog meat or raw vegetables and not drinking boiled or bottled water most of the time. Conclusions/Significance: This is the first study to explore the effectiveness of the reactive use of killed OCVs during a cholera outbreak. Our findings suggest that killed OCVs may have a role in controlling cholera outbreaks. © 2011 Anh et al.


Bettarel Y.,Montpellier University | Thuy N.T.,National Institute of Hygiene and Epidemiology NIHE | Huy T.Q.,National Institute of Hygiene and Epidemiology NIHE | Hoang P.K.,Vietnamese National Institute of Oceanography VNIO | Bouvier T.,Montpellier University
Journal of the Marine Biological Association of the United Kingdom | Year: 2013

Virus-like particles were observed in thin sections of partially bleaching colonies of the scleractinian Acropora cytherea, collected in the Hon Mun Marine Protected Area (Vietnam). The most common particles were found in the cytoplasm of epidermal cells, exhibiting icosahedral symmetry and measuring 90-140 nm in diameter. Some had a tail-like structure resembling that of certain Hepadnaviridae such as the hepatitis B virus. Some others were tailless with a virion size. Overall, less than 10% of the cells showed obvious signs of infection. Images of virally-parasitized tissues of A. cytherea provide further evidence that corals are a target for viral infection. However, more research is required into their pathogenicity and involvement in bleaching events. Copyright © Marine Biological Association of the United Kingdom 2012.


van Tuan C.,Hanoi University of Science and Technology | Huy T.Q.,National Institute of Hygiene and Epidemiology NIHE | Van Hieu N.,Hanoi University of Science and Technology | Tuan M.A.,Hanoi University of Science and Technology | Trung T.,Hung Yen University of Technology and Education
Analytical Letters | Year: 2013

Polyaniline (PANI) conducting polymers have attracted increasing interest as a transducer material for biosensors applications. In this study, we demonstrate the use of PANI nanowires (NWs) as immobilization platforms in the configuration of an electrochemical immunosensor for label free detection of Japanese encephalitis virus. The PANI NWs were synthesized on the surface of an interdigitated platinum (Pt) microelectrode via electrochemical growth. The morphology and characteristics of the PANI NWs on the Pt microelectrode were verified by scanning electron microscopy and Fourier transform infrared spectroscopy. The anti- Japanese encephalitis virus polyclonal IgG antibody was then covalently immobilized on the PANI NWs-coated Pt microelectrode by using 1-ethyl-3-(3-dimethyaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimde (NHS). The detection of Japanese encephalitis virus antigens was analyzed by electrochemical impedance spectroscopy (EIS). The developed PANI NWs-based electrochemical immunosensor could detect the Japanese encephalitis virus with a detection limit below 10 ng/ml. The results from EIS analysis also indicate that when the PANI NWs were exposed to nonspecific molecules, a negligible response was found, and it did not impact to the specificity of the sensor in the virus detection. This work shows the potential use of PANI NWs in electrochemical immunosensors for label free detection of other pathogens and small biomolecules. © 2013 Copyright Taylor and Francis Group, LLC.


Huy T.Q.,Hanoi University of Science and Technology | Hanh N.T.H.,National Institute of Hygiene and Epidemiology NIHE | Van Chung P.,National Institute of Hygiene and Epidemiology NIHE | Anh D.D.,National Institute of Hygiene and Epidemiology NIHE | And 2 more authors.
Applied Surface Science | Year: 2011

In this paper, we describes different methods to immobilize Japanese encephalitis virus (JEV) antibodies in human serum onto the interdigitated surface of a microelectrode sensor for optimizing electrochemical detection: (1) direct covalent binding to the silanized surface, (2) binding to the silanized surface via a cross-linker of glutaraldehyde (GA), (3) binding to glutaraldehyde/silanized surface via goat anti-human IgG polyclonal antibody and (4) binding to glutaraldehyde/silanized surface via protein A (PrA). Field emission scanning electron microscopy, Fourier transform infrared spectrometry, and fluorescence microscopy are used to verify the characteristics of antibodies on the interdigitated surface after the serum antibodies immobilization. The analyzed results indicate that the use of protein A is an effective choice for immobilization and orientation of antibodies in serum for electrochemical biosensors. This study provides an advantageous immobilization method of serum containing antiviral antibodies to develop electrochemical biosensors for preliminary screening of viruses in clinical samples from outbreaks. © 2011 Elsevier B.V.


Tran Q.H.,National Institute of Hygiene and Epidemiology NIHE | Nguyen V.Q.,Hanoi University of Science and Technology | Le A.-T.,Hanoi University of Science and Technology
Advances in Natural Sciences: Nanoscience and Nanotechnology | Year: 2013

In recent years the outbreak of re-emerging and emerging infectious diseases has been a significant burden on global economies and public health. The growth of population and urbanization along with poor water supply and environmental hygiene are the main reasons for the increase in outbreak of infectious pathogens. Transmission of infectious pathogens to the community has caused outbreaks of diseases such as influenza (A/H, diarrhea (Escherichia coli), cholera (Vibrio cholera), etc throughout the world. The comprehensive treatments of environments containing infectious pathogens using advanced disinfectant nanomaterials have been proposed for prevention of the outbreaks. Among these nanomaterials, silver nanoparticles (Ag-NPs) with unique properties of high antimicrobial activity have attracted much interest from scientists and technologists to develop nanosilver-based disinfectant products. This article aims to review the synthesis routes and antimicrobial effects of Ag-NPs against various pathogens including bacteria, fungi and virus. Toxicology considerations of Ag-NPs to humans and ecology are discussed in detail. Some current applications of Ag-NPs in water-, air- and surface- disinfection are described. Finally, future prospects of Ag-NPs for treatment and prevention of currently emerging infections are discussed. © 2013 Vietnam Academy of Science & Technology.


Dinh N.X.,Hanoi University of Science and Technology | Quy N.V.,Hanoi University of Science and Technology | Huy T.Q.,National Institute of Hygiene and Epidemiology NIHE | Le A.-T.,Hanoi University of Science and Technology
Journal of Nanomaterials | Year: 2015

Recently, development of carbon nanocomposites composed of carbon nanostructures and metal nanoparticles has attracted much interests because of their large potential for technological applications such as catalyst, sensor, biomedicine, and disinfection. In this work, we established a simple chemistry method to synthesize multiwalled carbon nanotubes (MWCNTs) decorated with silver nanoparticles (Ag-NPs) using a modified photochemical reaction (Tollens process). The formation and interaction of Ag-NPs with functionalized groups on the surface of MWCNTs were analyzed by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. The average size of Ag-NPs on the MWCNTs was approximately 7 nm with nearly uniform size distribution. Antibacterial effect of Ag-MWCNTs nanocomposites was evaluated against two pathogenic bacteria including Gram-negative Escherichia Coli and Gram-positive Staphylococcus aureus bacteria. Interaction and bactericidal mechanism of Ag-MWCNTs with tested bacteria was studied by adapting the electron microscopy. Analysis on ultrastructural changes of bacterial cells indicates that antibacterial action mechanism of Ag-MWCNTs is physical interaction with cell membrane, the large formation of cell-Ag-MWCNTs aggregates, and faster destructibility of cell membrane and disruption of membrane function, hence resulting in cells death. © 2015 Ngo Xuan Dinh et al.


Huy T.Q.,Hanoi University of Science and Technology | Hanh N.T.H.,National Institute of Hygiene and Epidemiology NIHE | Thuy N.T.,National Institute of Hygiene and Epidemiology NIHE | Chung P.V.,National Institute of Hygiene and Epidemiology NIHE | And 2 more authors.
Talanta | Year: 2011

In this paper, we represent a label-free biosensor based on immobilization of serum antibodies for rapid detection of viral antigens. Human serum containing specific antibodies against Japanese encephalitis virus (JEV) was immobilized on a silanized surface of an interdigitated sensor via protein A/glutaraldehyde for electrical detection of JEV antigens. The effective immobilization of serum antibodies on the sensor surface was verified by Fourier transform infrared spectrometry and fluorescence microscopy. The signal of the biosensor obtained by the differential voltage converted from the change into non-Faradic impedance resulting from the specific binding of JEV antigens on the surface of the sensor. The detection analyzed indicates that the detection range of this biosensor is 1-10 μg/ml JEV antigens, with a detection limit of 0.75 μg/ml and that stable signals are measured in about 20 min. This study presents a useful biosensor with a high selectivity for rapid and simple detection of JEV antigens, and it also proposes the biosensor as a future diagnostic tool for rapid and direct detection of viral antigens in clinical samples for preliminary pathogenic screenings in the case of possible outbreaks. © 2011 Elsevier B.V. All rights reserved.


Nga N.K.,Hanoi University of Science and Technology | Hong P.T.T.,Hanoi University of Science and Technology | Lam T.D.,Vietnam Academy of Science and Technology | Huy T.Q.,National Institute of Hygiene and Epidemiology NIHE
Journal of Colloid and Interface Science | Year: 2013

Magnesium oxide (MgO) has been known as an excellent adsorbent for a variety of the environmentally polluted compounds. This work describes a synthesis of nanostructured MgO particles via a facile procedure by using cetyltrimethylammonium bromide (CTAB). Powder X-ray diffraction, thermal gravimetric, and differential thermal gravimetry (TGA/DTG) analyses were performed to characterize the physical properties of synthesized MgO particles and field emission-scanning electron microscopy (FE-SEM) was used to observe their morphology, whereas nitrogen adsorption-desorption isotherms and Brunauer-Emmett-Teller (BET) method were used to calculate the total surface areas of the samples. The adsorptive performance was studied by batch experiments for reactive blue (RB) 19 dye removal. The results showed that as-prepared MgO particles revealed hexagonal-like shaped platelets with an average diameter in the range of 49-91nm and a mean thickness of 19-25nm; meanwhile, MgO CTAB-free particles are aggregated, tiny nanoparticles with an average width of 22nm and an average length of 77nm. The maximum adsorption capacity of as-prepared nanostructured MgO for reactive blue (RB) 19 dye was 250mgg-1. Furthermore, the correlation between structural characterization (mean size, pore, surface) of the samples and the adsorption performance was also discussed in details. © 2013 Elsevier Inc.

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