Nguyen Hoang Nam

Magnetic properties of FePt nanoparticles prepared by sonoelectrodeposition

Sonoelectrodeposition is a useful technique to make metallic nanoparticles, using ultrasound during electrodeposition to remove nanoparticles as they grow on the cathode surface. This paper reports some structural and magnetic properties of FePt nanoparticles prepared by this method. The as-prepared Fe45Pt55 nanoparticles were ferromagnetic at room temperature. Upon annealing at 700°C for 1 h under H2 atmosphere, the saturation magnetization and the coercivity of the nanoparticles were improved significantly. The annealed nanoparticles showed a high coercivity of 13.5 kOe at 2 K and of 9 kOe at room temperature. Sonoelectrodeposition is a promising technique to make large quantity of FePt nanoparticles.

Hydrogen Gas Sensing Using Palladium-Graphene Nanocomposite Material Based on Surface Acoustic Wave

We report the fabrication and characterization of surface acoustic wave (SAW) hydrogen sensors using palladium-graphene (Pd-Gr) nanocomposite as sensing material. The Pd-Gr nanocomposite as sensing layer was deposited onto SAW delay line sensor-based interdigitated electrodes (IDTs)/aluminum nitride (AlN)/silicon (Si) structure. The Pd-Gr nanocomposite was synthesized by a chemical route and deposited onto SAW sensors by air-brush spraying. The SAW H2 sensor using Pd-Gr nanocomposite as a sensing layer shows a frequency shift of 25 kHz in 0.5% H2 concentration at room temperature with good repeatability and stability. Moreover, the sensor showed good linearity and fast response/recovery within ten seconds with various H2 concentrations from 0.25 to 1%. The specific interaction between graphene and SAW transfer inside AlN/Si structures yields a high sensitivity and fast response/recovery of SAW H2 sensor based on Pd-Gr/AlN/Si structure.

Specificity and processing rate enhancement of Mycobacterium tuberculosis diagnostic procedure using antibody–coupled magnetic nanoparticles

Mycobacterium tuberculosis (MTB) is the immediate cause of one of the most dangerous lung diseases that threaten developing countries, where the number of patients diagnosed with multi–drug resistant (MDR) strains is increasing significantly. In this study, we have developed a new diagnostic procedure using magnetic nanoparticles functionalised with amino group (NP–NH2) to couple with anti–MTB antibody for a more specific PCR–based detection method. The results show that the NP–NH2–antibody complex generated through 1–ethyl–3–[3–dimethylaminopropyl] carbodiimide (EDC) coupling allows rapid and specific detection of Mycobacterium bovis from the BCG vaccine which possesses the signature IS6110 sequence widely used in MTB diagnosis. Furthermore, this complex is stable and provides reproducible detection for at least 4 weeks when stored in phosphate–buffered saline solution with Tween, bovine serum albumin (BSA) and sodium azide (PBS–TBN) at 4oC. As a result, the required time for the whole procedure to prepare samples for PCR could be completed within an hour owing to the elimination of the DNA purification step. We have tested this method on sputum samples collected from Vietnam Hospital 103 thus proving its validity. Further experiments are underway to employ the magnetic feature of the NP–NH2–antibody complex to develop an automated kit facilitating high throughput screening and reducing contamination risk.

Study of nanostructured polymeric composites used for organic light emitting diodes and organic solar cells

Polymeric nanocomposite films from PEDOT and MEH-PPV embedded with surface modified TiO2 nanoparticles were prepared, respectively for the hole transport layer (HTL) and emission layer (EL) in Organic Light Emitting Diodes (OLED). The composite of MEH-PPV + nc-TiO2 was used for Organic Solar Cells (OCS). The results from the characterization of the properties of the nanocomposites and devices showed that electrical (I-V characteristics) and spectroscopic (photoluminescent) properties of the conjugate polymers were enhanced due to the incorporation of nc-TiO2 in the polymers. The OLEDs made from the nanocomposite films would exhibit a larger photonic efficiency and a longer lasting life. For the OSC made from MEH-PPV + nc-TiO2 composite, the fill factor (FF) reached a value as high as 0.34. Under illumination of light with a power density of 50 mW/cm2, the photoelectrical conversion efficiency (PEC) was found to be of 0.15% corresponding to an open circuit voltage VOC = 1.15 V and a short-cut circuit curre...

New biological treatment targeting Mycobacterium tuberculosis in contaminated wastewater using lysing enzymes coupled to magnetic nanoparticles

Abstract Wastewater from hospitals and facilities that receive patients infected with contagious microorganisms has dense concentrations of these pathogens, which may represent a threat to public health. Thus, proper wastewater treatment to remove these contaminants before discharging to the sewage system has been a great concern to the society. Aside from chemical and physical treatment, biological alternatives have been more widely studied and implemented for wastewater processing to avoid unwanted effects and to lower the costs. This study aimed to use lysing enzymes coupled to magnetic amino nanoparticles functionalized with specific antibodies (NP-NH2-antibody) to treat wastewater contaminated with targeted contagious pathogens, initially with Mycobacterium tuberculosis, a highly persistent bacterium. The generated complexes captured Mycobacterium bovis in Bacillus Calmette-Guérin (BCG; tuberculosis vaccine), which was subsequently lysed by lysozyme and lipase. The result showed that single complexes (functionalized with either enzyme or antibody) worked more efficiently than dual complexes (coupled to both proteins) and the complexes could be stored refrigerated stably for at least two months. The preliminary assessment of this method in treating wastewater model samples spiked with BCG vaccine showed evidence for the bacteria being captured and eliminated. Further optimization is necessary to implement these complexes in treating pathogen-contaminated wastewater.