Faculty Profiles - SAITO, Nagahiro

Papers - SAITO, Nagahiro

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High Efficiency DNA Extraction by Graphite Oxide/Cellulose/Magnetite Composites Under Na<sup>+</sup> Free System

Akceoglu G., Li O., Saito N.

JOM Vol. 68 ( 4 ) page： 1071 - 1077 2016.4

Language：English Publishing type：Research paper (scientific journal) Publisher：JOM

DNA extraction is the key step at various research areas like biotechnology, diagnostic development, paternity determination, and forensic science. Solid support extraction is the most common method for DNA purification. In this method, Na+ ions have often been applied as binding buffers in order to obtain high extraction efficiency and high quality of DNA; however, the presence of Na+ ions might be interfering with the downstream DNA applications. In this study, we proposed graphite oxide (GO)/magnetite composite/cellulose as an innovative material for Na+-free DNA extraction. The total wt.% of GO was fixed at 4.15% in the GO/cellulose/magnetite composite. The concentration of magnetite within the composites were controlled at 0–3.98 wt.%. The extraction yield of DNA increased with increasing weight percentage of magnetite. The highest yield was achieved at 3.98 wt.% magnetite, where the extraction efficiency was reported to be 338.5 ng/µl. The absorbance ratios between 260 nm and 280 nm (A260/A280) of the DNA elution volume was demonstrated as 1.81, indicating the extracted DNA consisted of high purity. The mechanism of adsorption of DNA was provided by (1) π–π interaction between the aromatic ring in GO and nucleobases of DNA molecule, and (2) surface charge interaction between the positive charge magnetite and anions such as phosphates within the DNA molecules. The results proved that the GO/cellulose/magnetite composite provides a Na+-free method for selective DNA extraction with high extraction efficiency of pure DNA.

DOI： 10.1007/s11837-016-1826-0

Nitrogen-Doped Carbon Nanoparticle-Carbon Nanofiber Composite as an Efficient Metal-Free Cathode Catalyst for Oxygen Reduction Reaction

Panomsuwan G., Saito N., Ishizaki T.

ACS Applied Materials and Interfaces Vol. 8 ( 11 ) page： 6962 - 6971 2016.3

Language：English Publishing type：Research paper (scientific journal) Publisher：ACS Applied Materials and Interfaces

Metal-free nitrogen-doped carbon materials are currently considered at the forefront of potential alternative cathode catalysts for the oxygen reduction reaction (ORR) in fuel cell technology. Despite numerous efforts in this area over the past decade, rational design and development of a new catalyst system based on nitrogen-doped carbon materials via an innovative approach still present intriguing challenges in ORR catalysis research. Herein, a new kind of nitrogen-doped carbon nanoparticle-carbon nanofiber (NCNP-CNF) composite with highly efficient and stable ORR catalytic activity has been developed via a new approach assisted by a solution plasma process. The integration of NCNPs and CNFs by the solution plasma process can lead to a unique morphological feature and modify physicochemical properties. The NCNP-CNF composite exhibits a significantly enhanced ORR activity through a dominant four-electron pathway in an alkaline solution. The enhancement in ORR activity of NCNP-CNF composite can be attributed to the synergistic effects of good electron transport from highly graphitized CNFs as well as abundance of exposed catalytic sites and meso/macroporosity from NCNPs. More importantly, NCNP-CNF composite reveals excellent long-term durability and high tolerance to methanol crossover compared with those of a commercial 20 wt % supported on Vulcan XC-72. We expect that NCNP-CNF composite prepared by this synthetic approach can be a promising metal-free cathode catalyst candidate for ORR in fuel cells and metal-air batteries.

DOI： 10.1021/acsami.5b10493

Electrocatalytic oxygen reduction on nitrogen-doped carbon nanoparticles derived from cyano-aromatic molecules via a solution plasma approach

Panomsuwan G., Saito N., Ishizaki T.

Carbon Vol. 98 page： 411 - 420 2016.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Carbon

Metal-free nitrogen-doped carbon nanoparticles (NCNPs) have been synthesized via a solution plasma process with the potential to achieve uniformly distributed nitrogen atoms. A set of cyano-aromatic molecules, including benzonitrile, 2-cyanopyridine, and cyanopyrazine, were used as a single-source precursor in the synthesis without the addition of a metal catalyst source. The resultant NCNPs reveal uniformly nanosized particles (20-40 nm) and an interconnected hierarchical pore structure with a high specific surface area (210-250 m2 g-1). The difference in carbon/nitrogen mole ratios of organic precursors gives rise to the variation of nitrogen-doping level in NCNPs from 0.63 to 1.94 atom %. Detailed electrochemical evaluation toward the oxygen reduction reaction (ORR) demonstrates that NCNPs exhibit a significant improvement in terms of both onset potential and current density under alkaline and acidic conditions. The predominant distribution of graphitic-N and pyridinic-N sites on NCNPs plays an essential role in enhancing the ORR activity and the selectivity toward a four-electron reduction pathway. More importantly, NCNPs possess excellent robust long-term durability and strong methanol tolerance compared with those of a commercial Pt/carbon catalyst.

DOI： 10.1016/j.carbon.2015.11.013

Synthesis of Fe-Cu bi-functional catalysts by solution plasma process for li-air battery application

Li O.L., Takahashi R., Urashima K., Saito N.

International Journal of Plasma Environmental Science and Technology Vol. 10 ( 1 ) page： 51 - 56 2016.3

Language：English Publishing type：Research paper (scientific journal) Publisher：International Journal of Plasma Environmental Science and Technology

This research reported an innovative method to synthesize inexpensive and bi-functional catalyst electrode material for the application in Li-air battery. Non-novel metal, Cu and Fe were served, respectively, as alternative Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER). Solution Plasma Process was applied to synthesized Cu-Fe metal nanoparticles and carbon nanoparticles simultaneously. SPP was generated in benzene 100 mL using a bipolar pulse power supply. Iron and copper of diameter 1.0 mm were used for the discharge electrode and precursor of the bimetallic nanoparticles. Solution was reacted and stirred continuously for 20 minutes. Based on the amount of electrode consumption and ICP-AES analysis, the percentage of Cu and Fe supported on carbon were respectively, 2.8 and 1.0 wt%. The diameter of metal nanoparticles was approximately 10 nm, where the carbon nanoparticles ranged between 20-30 nm. From XRD analyses, the presences of Cu, Fe and CuFe2O4 were confirmed. In the performance of cyclic voltammetry, Fe and Cu nanoparticles showed the catalytic activity, respectively, for ORR and OER, at -0.38 and above 0.5 V. In the case of Fe-Cu bimetallic nanoparticles, it showed the combined catalytic activities of the single particles.

Analysis of benzoquinone decomposition in solution plasma process

Bratescu M., Saito N.

Journal of Instrumentation Vol. 11 ( 1 ) 2016.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Instrumentation

The decomposition of p-benzoquinone (p-BQ) in Solution Plasma Processing (SPP) was analyzed by Coherent Anti-Stokes Raman Spectroscopy (CARS) by monitoring the change of the anti-Stokes signal intensity of the vibrational transitions of the molecule, during and after SPP. Just in the beginning of the SPP treatment, the CARS signal intensities of the ring vibrational molecular transitions increased under the influence of the electric field of plasma. The results show that plasma influences the p-BQ molecules in two ways: (i) plasma produces a polarization and an orientation of the molecules in the local electric field of plasma and (ii) the gas phase plasma supplies, in the liquid phase, hydrogen and hydroxyl radicals, which reduce or oxidize the molecules, respectively, generating different carboxylic acids. The decomposition of p-BQ after SPP was confirmed by UV-visible absorption spectroscopy and liquid chromatography.

DOI： 10.1088/1748-0221/11/01/C01009

Adsorption of carbon dioxide by solution-plasma-synthesized heteroatom-doped carbon nanospheres

Thongwichit N., Helena Li O.L., Yaowarat W., Saito N., Suriyapraphadilok U.

Japanese Journal of Applied Physics Vol. 55 ( 1 ) 2016.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics

Porous carbon nanospheres (CNSs) synthesized by a plasma-in-liquid technique were applied as an adsorbent for CO2 adsorption. Two different types of aromatic solvents, benzene and pyridine, were used as precursors to generate CNSs. The prepared CNSs were carbonized and then activated with CO2 to obtain carbon materials with a suitable porous structure for CO2 adsorption. To improve CO2 adsorption capacity, activated CNSs were then chemically modified using different approaches of surface treatment, namely, HNO3 oxidation, amination without HNO3 preoxidation, and amination with HNO3 preoxidation. The CO2 adsorption capacities of the samples were investigated at 1 atm and 40 °C using a simultaneous thermal analyzer. It was found that the CO2 adsorption of CNSs was enhanced through the development of textural properties. All of the surface treatment approaches led to the increase in CO2 adsorption capacity of the activated CNSs owing to the presence of nitrogen or oxygen functional groups introduced onto the carbon surface during the treatment.

DOI： 10.7567/JJAP.55.01AE10

Highly durable silica-coated Pt/carbon nanotubes for proton-exchange membrane fuel cells application

Yaowarat W., Helena Li O.L., Saito N.

Japanese Journal of Applied Physics Vol. 55 ( 1 ) 2016.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics

Platinum nanoparticles supported on carbon nanotubes (Pt/CNTs) have been used as an electrocatalyst in proton-exchange membrane fuel cells (PEMFCs). These catalysts show higher activity in oxygen reduction reaction in PEMFCs than conventional carbon-black-supported Pt nanoparticles. However, their durability is lower than that of other metal-alloy-based or nonmetal-based catalysts. In this study, Pt/CNTs were synthesized by solution plasma followed by coating with silica layer by the sol-gel method using a cationic surfactant [cetyltrimethylammonium bromide (CTAB)]. This material can be used as a cathode in PEMFCs. The silica layer was coated on the surface of Pt/CNTs to prevent agglomeration and detachment of Pt nanoparticles from carbon nanotubes during operation. The formation of silica layers significantly improved the durability of the Pt/CNT catalysts under acidic conditions. After 300 cycles of the cyclic voltammetry test in 0.5#M sulfuric acid (H2SO4), silicacoated Pt/CNTs increased the durability by 43.0 and 24.0% compared with those of noncoated commercial Pt/C and Pt/CNTs, respectively.

DOI： 10.7567/JJAP.55.01AE23

Synthesis of nitrogen-containing carbon by solution plasma in aniline with high-repetition frequency discharges

Hyun K., Ueno T., Saito N.

Japanese Journal of Applied Physics Vol. 55 ( 1 ) 2016.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics

Nitrogen-containing carbon nanoparticles were synthesized in aniline by solution plasma with high-repetition frequency discharges. We developed a bipolar pulsed power supply that can apply high-repetition frequencies ranging from 25 to 200 kHz. By utilizing high-repetition frequencies, conductive carbons were directly synthesized. The crystallinity was increased and H/C ratio of carbon was decreased. Furthermore, nitrogen atoms were simultaneously embedded in the carbon matrix. Due to the presence of nitrogen atoms, the conductivity and electrocatalytic activity of the samples were remarkably improved compared to that of a pure carbon matrix synthesized from a benzene precursor.

DOI： 10.7567/JJAP.55.01AE18

Synthesis of SnO<inf>2</inf> nanoparticles using a solution plasma and their gas-sensing properties

Zhang J., Hu X., Shi J., Lu P., Shen X., Xu P., Saito N.

Japanese Journal of Applied Physics Vol. 55 ( 1 ) 2016.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics

A simple solution plasma method was applied to the synthesis of SnO2 nanoparticles directly from tin(II) chloride solution, without adding any precipitant, stabilizer, or other agents at atmospheric pressure, because solution plasma provides a reaction field with a highly excited energy state. The results of X-ray power diffraction (XRD) analysis and transmission electron microscopy (TEM) verified that well-crystallized SnO2 nanoparticles in the size range of 2-5 nm were synthesized. SnO2 nanoparticles show satisfactory sensitivities to acetaldehyde and ethanol.

DOI： 10.7567/JJAP.55.01AE17

A simple synthesis method for nanostructured Co-WC/carbon composites with enhanced oxygen reduction reaction activity

Kang J., Kim H., Saito N., Lee M.

Science and Technology of Advanced Materials Vol. 17 ( 1 ) page： 37 - 44 2016

Language：English Publishing type：Research paper (scientific journal) Publisher：Science and Technology of Advanced Materials

Co nanoparticles (Co NPs) and nanoscale tungsten carbide (WC) are successfully synthesized simultaneously with mesoporous structured carbon black (C) using an innovative simple method, which is known as solution plasma processing (SPP), and NPs are also loaded onto carbon black at the same time by SPP. The introduction of Co NPs led to not only superior oxygen reduction reaction (ORR) activity in terms of onset potential and peak potential, but also to a more efficient electron transfer process compared to that of pure WC. Co-WC/C also showed durability for long-term operation better than that of commercial Pt/C. These results clearly demonstrate that the presence of Co NPs significantly enhanced the ORR and charge transfer number of neighboring WC NPs in ORR activities. In addition, it was proved that SPP is a simple method (from synthesis of NPs and carbon black to loading on carbon black) for the large-scale synthesis of NP-carbon composite. Therefore, SPP holds great potential as a candidate for nextgeneration synthetic methods for the production of NP-carbon composites.

DOI： 10.1080/14686996.2016.1140305

DFT calculation of oxygen adsorption on a core-single shell ZnNb catalyst

Morishita T., Ueno T., Panomsuwan G., Hieda J., Antoaneta Bratescu M., Saito N.

RSC Advances Vol. 6 ( 100 ) page： 98091 - 98095 2016

Language：English Publishing type：Research paper (scientific journal) Publisher：RSC Advances

Oxygen adsorption onto Pt, Nb, and core-single shell ZnNb particles is studied using ab initio molecular orbital (MO) calculations to realize their ability for the oxygen reduction reaction (ORR). The calculations demonstrate that the electronic state of oxygen adsorption on core-single shell ZnNb is very close to that on Pt, rather than that on Nb. The energy levels of the oxygen 2pσ∗ orbital and the antibonding orbital formed by the oxygen 2pπ∗ and metal d orbitals are different depending on the type of catalyst. In contrast, the energy level of the Nb-O π∗ (O2 2pπ∗ + Nb 4d antibonding) orbital of the core-single shell ZnNb is located at a position close to that of Pt. Our finding suggests that the oxygen adsorbed on the core-single shell ZnNb particle can easily be dissociated and desorbed owing to the disappearance of the interaction between the oxygen and Nb subsurface atoms through the replacement of Zn. We expect that core-single shell ZnNb can be utilized as an efficient and cost-effective catalyst for the ORR in a polymer electrolyte fuel cell.

DOI： 10.1039/c6ra19311k

Effect of treatment time in the Mg(OH)<inf>2</inf>/Mg–Al LDH composite film formed on Mg alloy AZ31 by steam coating on the corrosion resistance

Kamiyama N., Panomsuwan G., Yamamoto E., Sudare T., Saito N., Ishizaki T.

Surface and Coatings Technology Vol. 286 page： 172 - 177 2016

Language：English Publishing type：Research paper (scientific journal) Publisher：Surface and Coatings Technology

The corrosion resistant films were fabricated on Mg alloy AZ31 substrates by steam coating method using Al(NO3)3·9H2O aqueous solution as a steam source. The treatment temperature was maintained at 433 K, while the treatment time was varied at 3, 5, 7 and 9 h. X-ray diffraction (XRD) analysis demonstrated that the coated films were composed of a mixed structure of Mg(OH)2 and Mg–Al layered double hydroxide (Mg–Al LDH) phases. As revealed by the scanning electron microscopy (SEM) observation, the surface of coated films had a good uniformity of changing treatment times. The deposition rate increased exponentially with increasing treatment time. Fourier transform infrared (FT-IR) spectra showed that carbonate and nitrate ions were co-existed in the interlayer of Mg–Al LDH. The potentiodynamic polarization curves of the film coated for 7 h exhibited the lowest corrosion current density, which was almost four orders of magnitude lower than that of bare AZ31. The enhanced corrosion resistance was well consistent with the increase of Mg–Al LDH content in the films.

DOI： 10.1016/j.surfcoat.2015.11.051

Effect of microstructure on corrosion resistance and heat resistance of flame-resistant Ca-added magnesium alloy AZ61

Serizawa A., Iwase Y., Sudare T., Saito N., Kamiyama N., Ishizaki T.

Keikinzoku/Journal of Japan Institute of Light Metals Vol. 66 ( 1 ) page： 9 - 14 2016

Language：English Publishing type：Research paper (scientific journal) Publisher：Keikinzoku/Journal of Japan Institute of Light Metals

Effect of microstructure on corrosion resistance and heat resistance of flame-resistant Ca-added magnesium alloy AZ61 (AZX612) were investigated. An extruded and twin-rolled casting magnesium alloys AZX612 were used with a view to better understanding the relationship between microstructure and these properties. The microstructures of the magnesium alloys were characterized by optical microscope (OM), X-ray diffraction (XRD) and scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS). The shapes of compounds in the alloys observed by EDS were significantly different; spherical distribution in grain for the extruded magnesium alloy and preferential formation on grain boundaries for the twin-rolled casting magnesium alloy. The different microstructure of the two alloys resulted in showing the different properties. Immersion test in 5 mass% NaCl aqueous solution revealed that the corrosion rates for the extruded and twin-rolled casting magnesium alloys AZX612 were estimated to be 6.5 and 15.0 mm/year, respectively, indicating that the corrosion resistance of the extruded magnesium alloys AZX612 were more superior than that of the twin-rolled casting one. On the contrary, the heat resistance of the alloy did not change depending on the microstructure.

DOI： 10.2464/jilm.66.9

Enhancement of conductivity in nano carbon balls by the addition of carbon tetrachloride: Via room temperature solution plasma process

Li O.L., Hayashi H., Ishizaki T., Saito N.

RSC Advances Vol. 6 ( 57 ) page： 51864 - 51870 2016

Language：English Publishing type：Research paper (scientific journal) Publisher：RSC Advances

The conductivity of carbon nanoballs (CNBs) was enhanced by two orders of magnitude with the addition of carbon tetrachloride through a room temperature solution plasma process without post-heat treatment. The synthesized CNBs demonstrated the lowest resistivity of 8 Ω cm when the ratio of benzene to carbon tetrachloride was adjusted to 3:2. The morphologies from Transmission Electron Microscopy (TEM) showed the benzene-synthesized CNBs appeared as amorphous carbon while CNBs generated from the mixture of carbon tetrachloride and benzene were presented as short range graphite with turbostratic structure. From Raman spectroscopy and X-ray diffraction patterns, the results indicated the transition from amorphous carbon to nanocrystalline-graphite (NCG). From chemical elemental analysis, the hydrogen mole percentage decreased 20-50% when 20-60 vol% of carbon tetrachloride was added into benzene. We expect that this approach can be extended to enhance the conductivity of all kinds of amorphous carbonaceous materials in other synthesis technologies under room temperature.

DOI： 10.1039/c6ra02453j

Fe-N-doped carbon-based composite as an efficient and durable electrocatalyst for the oxygen reduction reaction

Panomsuwan G., Saito N., Ishizaki T.

RSC Advances Vol. 6 ( 115 ) page： 114553 - 114559 2016

Language：English Publishing type：Research paper (scientific journal) Publisher：RSC Advances

We herein report the preparation of an Fe-N-doped carbon nanoparticle-carbon nanofiber (Fe-N-CNP-CNF) composite using a solution plasma process followed by heat treatment. The resulting Fe-N-CNP-CNF exhibits excellent catalytic activity, durability, and methanol tolerance for the oxygen reduction reaction (ORR) in an alkaline solution. The enhanced ORR activity of Fe-N-CNP-CNF can reasonably be attributed to the synergistic contributions provided by a high degree of graphitization of CNF, meso/macroporosity of CNP, presence of catalytically active sites for ORR (i.e., graphitic N and Fe-N bond), and existence of carbon-encapsulated Fe/Fe3C particles.

DOI： 10.1039/C6RA24214F

Synthesis of colloidal MnO<inf>2</inf> with a sheet-like structure by one-pot plasma discharge in permanganate aqueous solution

Kim H., Watthanaphanit A., Saito N.

RSC Advances Vol. 6 ( 4 ) page： 2826 - 2834 2016

Language：English Publishing type：Research paper (scientific journal) Publisher：RSC Advances

Stable colloidal MnO2 - consisting of MnO2 with a sheet-like structure - was synthesized by solution plasma process (SPP). The synthesis was completed in one-step by discharging the plasma in potassium permanganate (KMnO4) aqueous solution without using any dispersants or stabilizers. An alteration of the manganese oxide oxidation state, from MnO4- to MnO2 as a function of the discharge time, was investigated by UV-vis spectroscopy. Morphology and elemental constituents were observed by TEM and EDS mapping. Results indicated that the discharge time was an important feature for the formation of MnO2 in the SPP system. Specifically at neutral pH (pH = 7), MnO4- was completely reduced to MnO2 within a discharge time of 18 min. After that the obtained MnO2 was converted rapidly to Mn2+. To better understand the possible pathways of MnO2 formation by the SPP, we compared aspects of the reaction under different pH conditions. Formation of MnO2 under additional, controlled pH conditions, i.e. 2 and 12, was studied. Results suggested that hydrogen species played a key role for the reduction of MnO4- in the water-based SPP system. In comparison to the existing routes for the synthesis of MnO2 nanosheets with a single or low number of layers, the SPP holds excellent promise as an effective alternative means regarding its simplicity, time-energy preserving, and scalability.

DOI： 10.1039/c5ra20416j

Synthesis of heteroatom-carbon nanosheets by solution plasma processing using: N -methyl-2-pyrrolidone as precursor

Hyun K., Ueno T., Li O., Saito N.

RSC Advances Vol. 6 ( 9 ) page： 6990 - 6996 2016

Language：English Publishing type：Research paper (scientific journal) Publisher：RSC Advances

Nitrogen-carbon nanosheets (NCNS), composed of multi-layer graphene with turbostratic stacking, were successfully synthesized through a solution plasma processing (SPP) at room temperature and an atmospheric pressure. The plasma was generated in 200 mL of N-methyl-2-pyrrolidone (NMP), which was applied as the carbon and nitrogen precursors. The NCNS presented an electrical resistivity of 0.065 Ω cm, which is comparable with that of N-doped carbon nanofibers (CNFs) and N-doped carbon nanotubes (CNTs). The synthesis rate of NCNS was 20 mg min-1. From the characteristics analyses, NCNS showed the surface area of 277 m2 g-1, a pore volume of 0.95 cm3 g-1 and a moderate nitrogen content of 1.3 at%. The synthesized NCNS also exhibited catalytic activity towards oxygen reduction reaction (ORR). This unique synthesis method can be applicable to synthesize multiple types of heteroatom-carbon nanosheets.

DOI： 10.1039/c5ra23659b

Verification of Radicals Formation in Ethanol-Water Mixture Based Solution Plasma and Their Relation to the Rate of Reaction

Sudare T., Ueno T., Watthanaphanit A., Saito N.

Journal of Physical Chemistry A Vol. 119 ( 48 ) page： 11668 - 11673 2015.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Physical Chemistry A

Our previous research demonstrated that using ethanol-water mixture as a liquid medium for the synthesis of gold nanoparticles by the solution plasma process (SPP) could lead to an increment of the reaction rate of ∼35.2 times faster than that in pure water. This drastic change was observed when a small amount of ethanol, that is, at an ethanol mole fraction (χethanol) of 0.089, was added in the system. After this composition, the reaction rate decreased continuously. To better understand what happens in the ethanol-water mixture-based SPP, in this study, effect of the ethanol content on the radical formation in the system was verified. We focused on detecting the magnetic resonance of electronic spins using electron spin resonance spectroscopy to determine the type and quantity of the generated radicals at each χethanol. Results indicated that ethanol radicals were generated in the ethanol-water mixtures and exhibited maximum quantity at the xethanol of 0.089. Relationship between the ethanol radical yield and the rate of reaction, along with possible mechanism responsible for the observed phenomenon, is discussed in this paper.

DOI： 10.1021/acs.jpca.5b07224

Adsorption and desorption of DNA tuned by hydroxyl groups in graphite oxides-based solid extraction material

Akceoglu G., Li O., Saito N.

Colloids and Surfaces B: Biointerfaces Vol. 136 page： 1 - 6 2015.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Colloids and Surfaces B: Biointerfaces

The extraction of DNA is the most crucial method used in molecular biology. Up to date silica matrices has been widely applied as solid support for selective DNA adsorption and extraction. However, since adsorption force of Si. OH functional groups is much greater than that of desorption force, the DNA extraction efficiency of silica surfaces is limited. In order to increase the DNA extraction yield, a new surface with different functional groups which possess of greater desorption property is required. In this study, we proposed cellulose/graphite oxide (GO) composite as an alternative material for DNA adsorption and extraction. GO/Cellulose composite provides the major adsorption and desorption of DNA by C. OH, which belongs to alkyl or phenol type of OH functional group. Compared to Si. OH, C. OH is less polarized and reactive, therefore the composite might provide a higher desorption of DNA during the elution process. The GO/cellulose composite were prepared in spherical structure by mixing urea, cellulose, NaOH, Graphite oxide and water. The concentration of GO within the composites were controlled to be 0-4.15. wt.%. The extraction yield of DNA increased with increasing weight percentage of GO. The highest yield was achieved at 4.15. wt.% GO, where the extraction efficiency was reported as 660.4. ng/μl when applying 2. M GuHCl as the binding buffer. The absorbance ratios between 260. nm and 280. nm (A260/A280) of the DNA elution was demonstrated as 1.86, indicating the extracted DNA consisted of high purity. The results proved that GO/cellulose composite provides a simple method for selective DNA extraction with high extraction efficiency of pure DNA.

DOI： 10.1016/j.colsurfb.2015.07.080

Influences of solution plasma conditions on degradation rate and properties of chitosan

Tantiplapol T., Singsawat Y., Narongsil N., Damrongsakkul S., Saito N., Prasertsung I.

Innovative Food Science and Emerging Technologies Vol. 32 page： 116 - 120 2015.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Innovative Food Science and Emerging Technologies

In this work, the effects of solution plasma conditions on the degradation rate and properties of chitosan are investigated. Various types of electrodes including tungsten (W), copper (Cu), and iron (Fe) were used. The treatment time and the applied pulse frequency of the bipolar supply varied from 0 to 210 min and 15 to 30 kHz, respectively. The plasma-treated chitosan was characterized by GPC, XRD, FT-IR, and fractionation analysis. The results showed that after plasma treatment for 210 min, the molecular weight of chitosan decreased remarkably, when compared to those of untreated samples. The plasma treatment of chitosan using Fe electrode and high pulse frequency strongly promoted the degradation rate of chitosan. The XRD analysis showed that the crystallinity of plasma-treated chitosan was destroyed. FT-IR analysis revealed that the chemical structure of chitosan was not changed by solution plasma treatment. Solution plasma treatment of chitosan using an Fe electrode provided the highest %yield of water-soluble chitosan. Industrial Relevance In this study, the solution plasma process is introduced to treat chitosan in order to prepare low-molecular-weight chitosan. According to our finding, the solution plasma could be a potential method for the preparation of low-molecular-weight chitosan and chitooligosaccharides. Since the solution plasma is generated under mild conditions (i.e.; the reaction proceeds at room temperature and ambient pressure), therefore, it is very attractive for the degradation of polysaccharide polymer and applicable to industrial materials process such as medicine, food, chemical industry, and cosmetics. In addition, we expected that plasma technology could be used instead of conventional enzymatic treatment and chemical treatment which was high cost and contamination process.

DOI： 10.1016/j.ifset.2015.09.014

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