Nguyen Thanh Binh

Surface modification of iron oxide nanoparticles and their conjuntion with water soluble polymers for biomedical application

Superparamagnetic iron oxide nanoparticles (SPION) coated with suitable bio-compatible substances have been used in biomedicine, particularly in magnetic resonance imaging (MRI), tissue engineering, and hyperthermia and drug delivery. In this study, we describe the synthesis of SPION and its surface modification for in-vitro experiments. The particle diameter and structure were estimated by FESEM, TEM, XRD analyses. The saturation magnetization was characterized. SPION with a mean size of 12 nm have been prepared under N2 atmosphere, with support of natural polymeric starch, by controlling chemical coprecipitation of magnetite phase from aqueous solutions containing suitable salts ratios of Fe2+ and Fe3+. The surface of SPION-nanoparticles was treated with a coordinatable agent for higher dispersion ability in water and remaining the superparamagnetic behavior. The prepared iron oxide nanoparticles were coated with starch, dextran, PEG or MPEG to extend the application potential in the quite different engineering field of nano biomedicine.

Fabrication and upconversion emission processes in nanoluminophores NaYF4: Er, Yb and NaYF4: Tm, Yb

In this paper we present the new results of fabrication, characterisation and upconversion emission process of NaYF4 nanoparticles doped with Er3+ or Tm3+and Yb3+ as sensitiser. In order to fabricate α–, β–NaYF4:2%Er3+, 19%Yb3+and α–, β–NaYF4:2%Tm3+, 19%Yb3+ nanoparticles the soft template method in isopropylamine at 140C and diethylene glycol (DEG) at 180C has been used. The morphology, structures and emission properties were studied by X–ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and luminescence spectroscopy. The upconversion luminescence (UCL) spectra of α and β crystalline forms of NaYF4:2%Er3+, 19%Yb3+and NaYF4:2%Tm3+, 19%Yb3+ nanoparticles were investigated upon diode laser excitation at 976 nm. The strong emissions in the green and red spectral regions were observed upon this excitation. The spectral lines of the UCL could be assigned to the upconversion radiative transitions of the Er3+ or Tm3+ ions with Yb3+ sensitiser. The upconversion emission spectra dependent on laser excitation powers have been investigated in order to elucidate the upconversion emission paths which could take place. We found the significant influence of the type of nanocrystalline structure on the upconverting radiative transition mechanisms in NaYF4:2%Er3+, 19%Yb3+and NaYF4:2%Tm3+, 19%Yb3+ nanoparticles.

Study on preparation and properties of a novel photo–catalytic material based on copper–centred metal–organic frameworks (Cu–MOF) and titanium dioxide

A Cu3BTC2 metal–organic framework (MOF) with large specific surface area of 1350 m2/g, where BTC = benzene–1,3,5–tricarboxylate, was synthesised by hydrothermal method. It was then used as a starting material for the preparation of a novel MOF based photocatalyst containing titanium dioxide. This photocatalyst, namely, TiO2@Cu3BTC2, has been prepared by hydrolysis of titanium (IV) isopropoxide under hydrothermal condition. The synthesised materials were then characterised by X–ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) techniques. The photocatalytic discolouration of methylene blue dye (MB) in aqueous solution was investigated under UV–VIS light irradiation at different illumination times using the photocatalyst TiO2@Cu3BTC2 metal–organic frameworks and a control sample of commercial TiO2 nano powder (Degussa P25). It is interesting to note that TiO2@Cu3BTC2 exhibits very strong photocatalytic activity for MB discolouration, much better than lone TiO2 nano–particles P25. Thus, this novel photocatalytic material based on copper–centred MOFs may serve as an excellent class of photocatalytic materials for different environmental applications.

Structural and luminescent properties of (Eu,Tb)PO4·H2O nanorods/nanowires prepared by microwave technique

Abstract Nanowires/nanorods of europium/terbium orthophosphate monohydrate with Eu 3+ concentration of 6, 11, and 20 at.% were prepared by microwave synthesis method. The effects of Eu 3+ doping concentration on structure, morphology and optical properties of nanomaterials were also investigated. The results showed that, for all studied Eu 3+ doping concentrations, a single-crystalline phase of rhabdophane-type (Eu,Tb)PO 4 ·H 2 O nanowires/nanorods was obtained by using microwave heating of an aqueous solution of terbium(III) nitrate, europium(III) nitrate and NH 4 H 2 PO 4 with pH=2. The length and width of these nanowires/nanorods ranged from 150 to 300 nm and from 10 to 50 nm, respectively. The evidence of energy transfer from Tb 3+ to Eu 3+ due to the energy overlap between the donor Tb 3+ and the acceptor Eu 3+ was observed obviously via a significant enhancement in the luminescent intensity of Eu 3+ .

Measurement of the Upper Tropospheric Density and Temperature Profiles in Hanoi Using a Raman Lidar

Abstract. The nitrogen molecular density and temperature profiles of the upper troposphere are measured by a Ra-man lidar system in Hanoi over the range from 3 km to 19 km. The spatial and temporal resolutions of profiles are60 m and 1h, respectively. The nitrogen molecular density profiles are directly calculated from the range-correctedlidar signal. The temperature profiles are derived from the molecular density profile based on the assumptions of thehydrostatic equilibrium, the ideal-gas law and a fixed nitrogen molecule ratio in the atmosphere. The results of ourlidar measurements show good agreement with the MSISE-90 atmospheric model. The maximum errors of density andtemperature measurements are 6% and 7%, respectively. We estimated the height of tropopause in Hanoi about 16 kmfrom the derived temperature profile. The measured density and temperature profiles from this Raman lidar can be usedfor studying the trends and characteristics of the upper troposphere in Hanoi.Keywords: upper troposphere, temperature profile, Raman lidar.

Measurements of the stratospheric Density and Temperature Profiles in Hanoi by a Rayleigh Lidar

The molecular density and temperature profiles of the stratosphere in Hanoi are measured by a Rayleigh lidar. The profiles have the spatial resolution of 120 m and the temporal resolution of 1h. Their bottom height and top height are 20 km and 57 km, respectively. The atmospheric molecule density profile is directly derived from the correction-range lidar signal. The temperature profile is deduced from the molecular density profile based on the assumptions of the hydrostatic equilibrium and the ideal-gas law. Lidar measurements show good agreement with the molecular density and the temperature profiles from the MSISE-90 atmospheric model. Maximum errors of the density and temperature are found to be 0:9% and 3:4 K, respectively. The position and the temperature of the stratopause in Hanoi are determined to be about 49 km and 270 K. Database of lidar in a long time might reveal the characteristic and the structure of the stratosphere in Hanoi, Vietnam.

Fluorescent Properties of Cancerous Liver Tissue

Fluorescence spectroscopy is a technology used fruitfully for biomedical diagnostics as well as for therapeutic purposes. The fluorescent analysis method are applied in biomedical diagnostics based on fluorescence of endogenous or exogenous fluorophores. We initially applied fluorescence spectroscopy for the study of human liver cancer (hepatocellular carcinoma) with an exogenous fluorophores, Radachlorinr 0.35%. The main aim of this study is to determine the spectral variation between normal and malignant liver tissues in 2 cases: the samples exposed and non-exposed to Radachlorin. The excitation wavelength used for the fluorescence measurements is 405 nm.

New nanomaterials for photonic application

A brief survey of the development of new nanomaterials for photonic application will be presented. Based on the photoresponsive sol gel nanohybrid of polymethamethyl acrylate, silica, and zirconia (ASZ) or titania (AST) have been fabricated some planar light guiding structures and devices. The lanthanide containing nanosphere with core/shell structures have been synthesized in using a modified solgel process. The opal like photonic crystal structures have been fabricated by self assembling technique.