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Rong Chen - One of the best experts on this subject based on the ideXlab platform.

  • HEPES involved hydrothermal synthesis of fe3o4 nanoparticles and their biological application
    RSC Advances, 2015
    Co-Authors: Hui Li, Zhong Lu, Gang Cheng, Kaifeng Rong, Fengxi Chen, Rong Chen
    Abstract:

    A simple one-step hydrothermal route was developed for the synthesis of magnetite (Fe3O4) nanoparticles in HEPES solution, using FeCl2 as the Fe(II) precursor. It was found that HEPES played an important role in the fabrication of Fe3O4 nanoparticles, where HEPES could act as a weak antioxidant to prevent the complete oxidation of Fe(II) to Fe(III). The possible formation mechanism of HEPES-coated Fe3O4 nanomaterials was also discussed. In the reaction system, the influence of inorganic anions on the morphologies of Fe3O4 nanostructures was also investigated. The as-synthesized spherical Fe3O4 nanoparticles with a concentration of 5–100 μg mL−1 exhibited nontoxicity towards HUVEC normal cells, indicating their potential application in biology. Combining the preparation of Ag and Au nanoparticles in HEPES solution, Ag/Fe3O4 and Au/Fe3O4 nanocomposites were successfully synthesized by a two-step method, which showed excellent antibacterial properties against S. aureus. Furthermore, the Ag/Fe3O4 and Au/Fe3O4 nanocomposites could be recycled and reused due to their superparamagnetic properties and retained their antibacterial activities.

  • controllable microwave and ultrasonic wave combined synthesis of zno micro nanostructures in HEPES solution and their shape dependent photocatalytic activities
    Journal of Alloys and Compounds, 2013
    Co-Authors: Qin Li, Rong Chen, Hui Li, Runming Wang, Guangfang Li, Hao Yang
    Abstract:

    Abstract Size- and morphology-controlled zinc oxide (ZnO) micro-/nanostructures have been successfully synthesized via a facile and rapid microwave and ultrasonic wave combined method in HEPES solution (HEPES = 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid). The as-prepared ZnO products are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and UV–vis diffuse reflection spectroscopy (DRS). Various morphologies of ZnO products, including grenade-like, column-like, spindle-like, rod-like, shuttle-like and flower-like micro-/nanostructures are obtained, which are strongly dependent on Zn/HEPES moral ratio, pH value and Zn precursor. It is found that HEPES plays a crucial role in the formation of ZnO micro-/nanostructures with controllable size and morphology. The photocatalytic activities of the prepared ZnO micro-/nanostructures are evaluated by degradation of methylene blue (MB) under UV light irradiation, among which spindle-like ZnO microstructures exhibit superior photocatalytic activity compared with other ZnO products.

  • hydrothermal synthesis and properties of controlled α fe2o3 nanostructures in HEPES solution
    Chemistry-an Asian Journal, 2011
    Co-Authors: Hui Li, Zhong Lu, Qin Li, Manho So, Rong Chen
    Abstract:

    : A facile, template-free, and environmentally friendly hydrothermal strategy was explored for the controllable synthesis of α-Fe(2)O(3) nanostructures in HEPES solution (HEPES=2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid). The effects of experimental parameters including HEPES/FeCl(3) molar ratio, pH value, reaction temperature, and reaction time on the formation of α-Fe(2)O(3) nanostructures have been investigated systematically. Based on the observations of the products, the function of HEPES in the reaction is discussed. The different α-Fe(2)O(3) nanostructures possess different optical, magnetic properties, and photocatalytic activities, depending on the shape and size of the sample. In addition, a novel and facile approach was developed for the synthesis of Au/α-Fe(2)O(3) and Ag/α-Fe(2)O(3) nanocomposites in HEPES buffer solution; this verified the dual function of HEPES both as reductant and stabilizer. This work provides a new strategy for the controllable synthesis of transition metal oxide nanostructures and metal-supported nanocomposites, and gives a strong evidence of the relationship between the property and morphology/size of nanomaterials.

  • hydrothermal synthesis of transition metal oxide nanomaterials in HEPES buffer solution
    Materials Letters, 2010
    Co-Authors: Hui Li, Zhong Lu, Jiliang Wu, Hui Yu, Xianglin Yu, Rong Chen
    Abstract:

    Abstract Various transition metal oxide (Co3O4, Mn3O4 and ZnO) nanostructures were readily synthesized in HEPES buffer solution (200 mmol/L, pH 7.40) via a simple hydrothermal method. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDX). It was found that the morphologies of the as-obtained transition metal oxide nanostructures were affected by the reaction temperature, HEPES/metal salt molar ratio and metal precursor. HEPES with two free nitrogen atoms (piperazine group) and terminal hydroxyl groups plays a critical role as a reactant and surfactant to prevent the transition metal oxide nanomaterials from aggregation.

  • Hydrothermal synthesis of platinum-group-metal nanoparticles by using HEPES as a reductant and stabilizer.
    Chemistry-an Asian Journal, 2010
    Co-Authors: Man‐ho So, Chi-ming Ho, Rong Chen
    Abstract:

    : Platinum-group-metal (Ru, Os, Rh, Ir, Pd and Pt) nanoparticles are synthesized in an aqueous buffer solution of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) (200 mM, pH 7.4) under hydrothermal conditions (180 degrees C). Monodispersed (monodispersity: 11-15%) metal nanoparticles were obtained with an average particle size of less than 5 nm (Ru: 1.8+/-0.2, Os: 1.6+/-0.2, Rh: 4.5+/-0.5, Ir: 2.0+/-0.3, Pd: 3.8+/-0.4, Pt: 1.9+/-0.2 nm). The size, monodispersity, and stability of the as-obtained metal nanoparticles were affected by the HEPES concentration, pH of the HEPES buffer solution, and reaction temperature. HEPES with two tertiary amines (piperazine groups) and terminal hydroxyl groups can act as a reductant and stabilizer. The HEPES molecules can bind to the surface of metal nanoparticles to prevent metal nanoparticles from aggregation. These platinum-group-metal nanoparticles could be deposited onto the surface of graphite, which catalyzed the aerobic oxidation of alcohols to aldehydes.

R L Martin - One of the best experts on this subject based on the ideXlab platform.

  • ionic basis of the membrane potential responses of rat dorsal vagal motoneurones to HEPES buffer
    Brain Research, 1996
    Co-Authors: A I Cowan, R L Martin
    Abstract:

    Abstract The effects of 10 mM HEPES ( N -2-hydroxyethylpiperazine- N -2-ethanesulfonic acid) buffered artificial cerebrospinal fluid (aCSF) on membrane potential and the action potential were studied in 93 dorsal vagal motoneurones (DVMs) using an in vitro slice preparation of the rat medulla. Changing from bicarbonate/CO 2 aCSF to HEPES aCSF resulted in a depolarisation of 6.0 ± 0.6 V and an increase in input resistance ( R In ; n = 61). In the presence of 5 mM 4-AP, HEPES either had little effect ( n = 9) or hyperpolarised the membrane ( n = 10). Mn 2+ (3 mM) or Ni 2+ (200 μm) abolished the hyperpolarisation and its associated increase in R In . In voltage-clamp studies 5 mM 4-AP eliminated a transient outward current and Ni 2+ blocked an inactivating inward current. It is concluded that HEPES buffer reduces the contribution of the A current to resting membrane potential and also reduces a Ni 2+ -sensitive transient I Ca .

  • simultaneous measurement of ph and membrane potential in rat dorsal vagal motoneurons during normoxia and hypoxia a comparison in bicarbonate and HEPES buffers
    Journal of Neurophysiology, 1995
    Co-Authors: Anna I Cowan, R L Martin
    Abstract:

    : 1. The effects of oxygenated and hypoxic bicarbonate/CO2, 10 and 25 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES)-buffered artificial cerebrospinal fluid (ACSF) have been studied in a rat brain slice preparation. Double-barreled pH-selective microelectrodes were used to measure intracellular pH (pHi) and membrane potential in dorsal vagal motoneurons (DVMs) and to measure extracellular pH (pHe) in the dorsal vagal motonucleus. 2. In bicarbonate ACSF, pHi averaged 7.24 +/- 0.05 (mean +/- SE, n = 21) and ranged from 6.86 to 7.79 pH units. pHe averaged 7.13 +/- 0.08 (n = 10). 3. On changing from oxygenated bicarbonate ACSF to either 10 or 25 mM HEPES ACSF, pHi decreased by 0.13-0.15 units, and the membrane depolarized by 10-11 mV. pHe also decreased in 10 mM HEPES ACSF (pHe 6.89 +/- 0.02, n = 8) but not in 25 mM HEPES ACSF (pHe 7.15 +/- 0.06, n = 3). In most neurons changes in pHi preceded changes in membrane potential. 4. In bicarbonate ACSF and in 25 mM HEPES ACSF, there was a significant linear relationship between prehypoxic pHi and the direction and amplitude of the hypoxia-induced membrane potential change (either an hyperpolarization or a depolarization). 5. In 10 mM HEPES ACSF, hypoxia always induced a depolarization; there was no correlation between prehypoxic pHi and the membrane potential response. 6. In bicarbonate ACSF and in 10 and 25 mM HEPES ACSF, hypoxia resulted in intracellular and extracellular acidification. However, the extracellular acidification in hypoxic 10 mM HEPES buffer was most pronounced (pH 6.40 +/- 0.11, n = 8), reflecting a preexisting extracellular acidification in oxygenated 10 mM HEPES buffer. 7. Various hypotheses that could give rise to a relationship between changes in membrane potential and pH are discussed; arguments are presented in favor of the concept that modulation of ion channels by either pHi or pHe, or both, is responsible for the observed correlations.

Chi-ming Ho - One of the best experts on this subject based on the ideXlab platform.

  • Hydrothermal synthesis of platinum-group-metal nanoparticles by using HEPES as a reductant and stabilizer.
    Chemistry-an Asian Journal, 2010
    Co-Authors: Man‐ho So, Chi-ming Ho, Rong Chen
    Abstract:

    : Platinum-group-metal (Ru, Os, Rh, Ir, Pd and Pt) nanoparticles are synthesized in an aqueous buffer solution of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) (200 mM, pH 7.4) under hydrothermal conditions (180 degrees C). Monodispersed (monodispersity: 11-15%) metal nanoparticles were obtained with an average particle size of less than 5 nm (Ru: 1.8+/-0.2, Os: 1.6+/-0.2, Rh: 4.5+/-0.5, Ir: 2.0+/-0.3, Pd: 3.8+/-0.4, Pt: 1.9+/-0.2 nm). The size, monodispersity, and stability of the as-obtained metal nanoparticles were affected by the HEPES concentration, pH of the HEPES buffer solution, and reaction temperature. HEPES with two tertiary amines (piperazine groups) and terminal hydroxyl groups can act as a reductant and stabilizer. The HEPES molecules can bind to the surface of metal nanoparticles to prevent metal nanoparticles from aggregation. These platinum-group-metal nanoparticles could be deposited onto the surface of graphite, which catalyzed the aerobic oxidation of alcohols to aldehydes.

  • Hydrothermal Synthesis of Platinum-Group-Metal Nanoparticles by Using HEPES as a Reductant and Stabilizer
    Chemistry - An Asian Journal, 2010
    Co-Authors: Manho So, Chi-ming Ho, Rong Chen
    Abstract:

    Platinum-group-metal (Ru, Os, Rh, Ir, Pd and Pt) nanoparticles are synthesized in an aqueous buffer solution of 4-(2-hydroxyethyl)-1-piper- azineethanesulfonic acid (HEPES) (200 mM, pH 7.4) under hydrothermal conditions (180 °C). Monodispersed (monodispersity: 11-15%) metal nanoparticles were obtained with an average particle size of less than 5 nm (Ru: 1.8±0.2, Os: 1.6±0.2, Rh: 4.5 ±0.5, Ir: 2.0±0.3, Pd: 3.8±0.4, Pt: 1.9±0.2 nm). The size, monodispersity, and stability of the as-obtained metal nanoparticles were affected by the HEPES concentration, pH of the HEPES buffer solution, and reaction temperature. HEPES with two tertiary amines (pi- perazine groups) and terminal hydroxyl groups can act as a reductant and stabilizer. The HEPES molecules can bind to the surface of metal nanoparticles to prevent metal nanoparticles from aggregation. These platinum- group-metal nanoparticles could be deposited onto the surface of graphite, which catalyzed the aerobic oxidation of alcohols to aldehydes. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.link_to_subscribed_fulltex

  • silver nanoparticles fabricated in HEPES buffer exhibit cytoprotective activities toward hiv 1 infected cells
    Chemical Communications, 2005
    Co-Authors: Rong Chen, Nancy P Y Chung, Chi-ming Ho
    Abstract:

    Silver nanoparticles fabricated in HEPES buffer exhibit potent cytoprotective and post-infected anti-HIV-1 activities toward Hut/CCR5 cells.

Hui Li - One of the best experts on this subject based on the ideXlab platform.

  • HEPES involved hydrothermal synthesis of fe3o4 nanoparticles and their biological application
    RSC Advances, 2015
    Co-Authors: Hui Li, Zhong Lu, Gang Cheng, Kaifeng Rong, Fengxi Chen, Rong Chen
    Abstract:

    A simple one-step hydrothermal route was developed for the synthesis of magnetite (Fe3O4) nanoparticles in HEPES solution, using FeCl2 as the Fe(II) precursor. It was found that HEPES played an important role in the fabrication of Fe3O4 nanoparticles, where HEPES could act as a weak antioxidant to prevent the complete oxidation of Fe(II) to Fe(III). The possible formation mechanism of HEPES-coated Fe3O4 nanomaterials was also discussed. In the reaction system, the influence of inorganic anions on the morphologies of Fe3O4 nanostructures was also investigated. The as-synthesized spherical Fe3O4 nanoparticles with a concentration of 5–100 μg mL−1 exhibited nontoxicity towards HUVEC normal cells, indicating their potential application in biology. Combining the preparation of Ag and Au nanoparticles in HEPES solution, Ag/Fe3O4 and Au/Fe3O4 nanocomposites were successfully synthesized by a two-step method, which showed excellent antibacterial properties against S. aureus. Furthermore, the Ag/Fe3O4 and Au/Fe3O4 nanocomposites could be recycled and reused due to their superparamagnetic properties and retained their antibacterial activities.

  • controllable microwave and ultrasonic wave combined synthesis of zno micro nanostructures in HEPES solution and their shape dependent photocatalytic activities
    Journal of Alloys and Compounds, 2013
    Co-Authors: Qin Li, Rong Chen, Hui Li, Runming Wang, Guangfang Li, Hao Yang
    Abstract:

    Abstract Size- and morphology-controlled zinc oxide (ZnO) micro-/nanostructures have been successfully synthesized via a facile and rapid microwave and ultrasonic wave combined method in HEPES solution (HEPES = 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid). The as-prepared ZnO products are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and UV–vis diffuse reflection spectroscopy (DRS). Various morphologies of ZnO products, including grenade-like, column-like, spindle-like, rod-like, shuttle-like and flower-like micro-/nanostructures are obtained, which are strongly dependent on Zn/HEPES moral ratio, pH value and Zn precursor. It is found that HEPES plays a crucial role in the formation of ZnO micro-/nanostructures with controllable size and morphology. The photocatalytic activities of the prepared ZnO micro-/nanostructures are evaluated by degradation of methylene blue (MB) under UV light irradiation, among which spindle-like ZnO microstructures exhibit superior photocatalytic activity compared with other ZnO products.

  • hydrothermal synthesis and properties of controlled α fe2o3 nanostructures in HEPES solution
    Chemistry-an Asian Journal, 2011
    Co-Authors: Hui Li, Zhong Lu, Qin Li, Manho So, Rong Chen
    Abstract:

    : A facile, template-free, and environmentally friendly hydrothermal strategy was explored for the controllable synthesis of α-Fe(2)O(3) nanostructures in HEPES solution (HEPES=2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid). The effects of experimental parameters including HEPES/FeCl(3) molar ratio, pH value, reaction temperature, and reaction time on the formation of α-Fe(2)O(3) nanostructures have been investigated systematically. Based on the observations of the products, the function of HEPES in the reaction is discussed. The different α-Fe(2)O(3) nanostructures possess different optical, magnetic properties, and photocatalytic activities, depending on the shape and size of the sample. In addition, a novel and facile approach was developed for the synthesis of Au/α-Fe(2)O(3) and Ag/α-Fe(2)O(3) nanocomposites in HEPES buffer solution; this verified the dual function of HEPES both as reductant and stabilizer. This work provides a new strategy for the controllable synthesis of transition metal oxide nanostructures and metal-supported nanocomposites, and gives a strong evidence of the relationship between the property and morphology/size of nanomaterials.

  • hydrothermal synthesis of transition metal oxide nanomaterials in HEPES buffer solution
    Materials Letters, 2010
    Co-Authors: Hui Li, Zhong Lu, Jiliang Wu, Hui Yu, Xianglin Yu, Rong Chen
    Abstract:

    Abstract Various transition metal oxide (Co3O4, Mn3O4 and ZnO) nanostructures were readily synthesized in HEPES buffer solution (200 mmol/L, pH 7.40) via a simple hydrothermal method. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDX). It was found that the morphologies of the as-obtained transition metal oxide nanostructures were affected by the reaction temperature, HEPES/metal salt molar ratio and metal precursor. HEPES with two free nitrogen atoms (piperazine group) and terminal hydroxyl groups plays a critical role as a reactant and surfactant to prevent the transition metal oxide nanomaterials from aggregation.

  • fabrication of gold nanoparticles with different morphologies in HEPES buffer
    Rare Metals, 2010
    Co-Authors: Rong Chen, Hui Li, Gang Cheng, Jiliang Wu, Zhong Lu
    Abstract:

    Gold nanoparticles with different morphologies, such as spindle, octahedron, and decahedron were obtained by using different molar ratios of HAuCl4/HEPES in the presence and absence of surfactants at room temperature. These nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), scanning electron microcopy (SEM), energy-dispersive X-rays analysis (EDX), and selected area electron diffraction (SAED). The kinetics of the formation of gold nanoparticles in HEPES buffer was studied by UV-visible spectrophotometer. The formation of gold nanoparticles was strongly dependent on the concentration of HEPES and pH value. The surfactants play a crucial role in the size and shape controlled synthesis of gold nanoparticles.

Manho So - One of the best experts on this subject based on the ideXlab platform.

  • hydrothermal synthesis and properties of controlled α fe2o3 nanostructures in HEPES solution
    Chemistry-an Asian Journal, 2011
    Co-Authors: Hui Li, Zhong Lu, Qin Li, Manho So, Rong Chen
    Abstract:

    : A facile, template-free, and environmentally friendly hydrothermal strategy was explored for the controllable synthesis of α-Fe(2)O(3) nanostructures in HEPES solution (HEPES=2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid). The effects of experimental parameters including HEPES/FeCl(3) molar ratio, pH value, reaction temperature, and reaction time on the formation of α-Fe(2)O(3) nanostructures have been investigated systematically. Based on the observations of the products, the function of HEPES in the reaction is discussed. The different α-Fe(2)O(3) nanostructures possess different optical, magnetic properties, and photocatalytic activities, depending on the shape and size of the sample. In addition, a novel and facile approach was developed for the synthesis of Au/α-Fe(2)O(3) and Ag/α-Fe(2)O(3) nanocomposites in HEPES buffer solution; this verified the dual function of HEPES both as reductant and stabilizer. This work provides a new strategy for the controllable synthesis of transition metal oxide nanostructures and metal-supported nanocomposites, and gives a strong evidence of the relationship between the property and morphology/size of nanomaterials.

  • Hydrothermal Synthesis of Platinum-Group-Metal Nanoparticles by Using HEPES as a Reductant and Stabilizer
    Chemistry - An Asian Journal, 2010
    Co-Authors: Manho So, Chi-ming Ho, Rong Chen
    Abstract:

    Platinum-group-metal (Ru, Os, Rh, Ir, Pd and Pt) nanoparticles are synthesized in an aqueous buffer solution of 4-(2-hydroxyethyl)-1-piper- azineethanesulfonic acid (HEPES) (200 mM, pH 7.4) under hydrothermal conditions (180 °C). Monodispersed (monodispersity: 11-15%) metal nanoparticles were obtained with an average particle size of less than 5 nm (Ru: 1.8±0.2, Os: 1.6±0.2, Rh: 4.5 ±0.5, Ir: 2.0±0.3, Pd: 3.8±0.4, Pt: 1.9±0.2 nm). The size, monodispersity, and stability of the as-obtained metal nanoparticles were affected by the HEPES concentration, pH of the HEPES buffer solution, and reaction temperature. HEPES with two tertiary amines (pi- perazine groups) and terminal hydroxyl groups can act as a reductant and stabilizer. The HEPES molecules can bind to the surface of metal nanoparticles to prevent metal nanoparticles from aggregation. These platinum- group-metal nanoparticles could be deposited onto the surface of graphite, which catalyzed the aerobic oxidation of alcohols to aldehydes. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.link_to_subscribed_fulltex