Mai Anh Tuan

DNA sensor development based on multi-wall carbon nanotubes for label-free influenza virus (type A) detection

This paper describes the DNA immobilization using carbon multi-walled nanotubes (MWCNTs) for direct and label-free detection of influenza virus (type A). The DNA probe was attached on the sensor surface by means of covalent bonding between the amine and phosphate groups of the DNA sequence. The interaction between the DNA probe and the MWCNTs were characterized by Fourier Transform Infrared (FTIR) spectrometry, Raman spectra. The hybridization of the DNA probe and the target DNA were detected by changes in the conductance on the surface of sensors leading to the change in the output signal of the system. The results show that the DNA sensor can detect as low as 0.5 nM of the target DNA samples; the response time of DNA sensor is approximately 4 min.

A novel biosensor based on serum antibody immobilization for rapid detection of viral antigens

Abstract 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 1–10μg/ml JEV antigens, with a detection limit of 0.75μg/ml and that stable signals are measured in about 20min. 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.

Polyaniline Nanowires-Based Electrochemical Immunosensor for Label Free Detection of Japanese Encephalitis Virus

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.

Synthesis of Cu\(^+\)/bipyridyl Based Complex Towards Dye Sensitized Solar Cell Application

This study aims to synthesize the Cu + /bipyridyl-based complex using Sonogashira cross coupling. The structure of the ligand and the complex were investigated by nuclear magnetic resonance spectroscopy; by single crystal X-ray diffraction and by UV-VIS absorption spectroscopy. The obtained experimental results were in good agreement with the theoretical calculations. The complex is a potential candidate to be the photo sensitizer in dye-sensitized solar cells.

Synthesis of coumarin derivatives based fluorescent dye towards the detection of cancer cell

Fluorescent readout is a powerful technique for the detection of cell cancer. The fluorescent biomarkers (or dyes) should exhibit the ability of the light emission when excited, and the biocompatibility. This work reports on the synthesis of coumarin derivatives based fluorescent dyes. The characterization results, obtained by NMR, HR-MS, absorption and emission spectroscopic method, revealed that these compounds are promising candidates for fluorescent biomarker applications. Keywords. Coumarin derivatives, fluorescence, biomarker, cancer cell, Palladium-catalyzed direct arylation.

Low resistivity molybdenum thin film towards the back contact of dye-sensitized solar cell

This paper reports the optimization of the molybdenum thin film electrode as the back contact of dye-sensitized solar cell (DSSC). The molybdenum thin film was grown on the glass substrate by direct current sputtering techniques of which the sputtering power was 150 W at 18 sccm flow rate of Ar. At such sputtering parameters, the Mo film can reach the lowest resistivity of 1.28E −6 Ω cm at 400 nm thick. And the reflection of Mo membrane was 82%. This value is considered as a very good result for preparation of the back contact of DSSC.

Impact parameters investigation of DNA immobilisation process on DNA sensor response

This paper studies impact parameters of DNA sequence immobilisation on DNA sensor response. The parameters were examined including immobilisation time, carbon nanotubes concentration, DNA probe concentration and pH value. The DNA probe sequences were immobilised on surface of microelectrodes by using multi–walled carbon nanotubes (MWCNTs) as mediator. The hybridisation between DNA probe and DNA target was detected by changes in the conductance on the surface of sensors leading to the change in the output signal of the system. The experimental results showed that DNA sensor can well detect E. coli O157:H7 bacteria at optimal parameters including immobilisation time of 120 minute, MWCNTs of 1 mg, 20 µM DNA probe and pH7. Additionally, influence of BSA agent blocking was also studied. The result showed that DNA sensor response was decrease about 15% compared to that obtained in the absence of BSA blocking.

Review: Possible removal of heavy metal and selective rare-earth ions by polymeric and nano-composite materials.

Heavy metal contamination in aqueous environment from natural processes and human’s activities including pesticides usage, mining, factories discharging and leaking irritation shows an extreme threat to environment and human health. The control of rising amount of heavy metal in environment not only requires critical observations at their original sources but also demands efficient removal methods. However, each conventional method is only suitable in a certain range of use. For example, inexpensive materials and convenient techniques are necessary for large scale heavy meal treatment, while high performance system to remove almost trace amount of heavy metals are critically required for drinking water treatment. On the other hands, heavy metal treatments must be applicable in some crucial environment conditions. Among solutions for environmental heavy metal control, polymeric materials have showed many advantages to enhance the performance of conventional heavy metal adsorbents. Possessing functional chemical moieties on their side chains and backbones, polymers can act as main metal ion adsorption component and/or effective supports for the adsorption property. In addition, the utilization of polymeric components can result in a low corrosion, selectivity, controllability, and recyclability of absorbents when operated in real environment conditions. This article summarizes the preparation techniques and desirable properties of polymer for removal of toxic heavy metal ion as well as the possibility of polymers in collecting some rare noble metal ions. Keywords. Heavy metal ions, nano-composite, polymer.

Theoretical Study on Ru2+, Cu+, and Fe2+ Complexes Toward the Application in Dye Sensitized Solar Cell

This paper reports the application of the Ru2+, Cu+, and Fe2+ complexes in form of RuL2(SCN)2, CuL2(SCN)2− for dye-sensitized solar cell (DSSC) development. The calculation results, given by quantum chemistry, demonstrated that the complex containing copper is more suitable than the one containing iron. The modification of Cu(I) complex by using various numbers of ligands enhanced photon absorption capacity as well as the absorption range. The addition of an organic ligand such as an electron attraction group to the benzene ring gave a better result as compared to the inorganic ones. Based on the analysis conducted, CuM2(SCN)2− is considered as potential material for N3 replacement.

Synthesis of Gold Nanoparticles Conjugated with Protein A: Towards the Application in Biosensors for Virus Detection

In this article, a facile and effective technique is described to prepare a complex of gold nanoparticles (GNPs)/protein A (PrA) for biosensors in virus detection. GNPs were synthesized by the reduction of tetrachloroauric (III) acid trihydrate using sodium ascorbate, and then coated with PrA via ultracentrifugation. The complex of GNPs/PrA was characterized using UV-vis spectroscopy and transmission electron microscopy. The immunogold labeling method of scanning electron microscopy was also used to verify the capacity for the detection and binding of GNPs/PrA to H