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Goncalo Apolinario De Souza Filho - One of the best experts on this subject based on the ideXlab platform.

Kiyotaka Sakai - One of the best experts on this subject based on the ideXlab platform.

  • Internal and surface structure characterization of cellulose triacetate hollow-fiber Dialysis Membranes
    Journal of Membrane Science, 2011
    Co-Authors: Kumiko Yamazaki, Ken-ichiro Yamamoto, Masato Matsuda, Taiji Yakushiji, Kiyotaka Sakai
    Abstract:

    Abstract A cellulose triacetate (CTA) Dialysis Membrane is generally regarded as a homogeneous Membrane. The objective of the present study was to characterize the internal structure of CTA Dialysis Membranes. We used FB-150E, FB-150F, and FB-150UH CTA hollow-fiber Membrane dialyzers. The pore-size distribution and porosity of the CTA Membrane surfaces were calculated from surface image data obtained by using atomic force microscopy (AFM). The internal porosity of the CTA Membranes was measured by weight analysis. Further, the pore diameter of the CTA Membranes was calculated from data on pure-water permeability and diffusive permeability using a pore diffusion model. The pore diameters on the inner surface of the CTA Membranes were much greater than those on the outer surface. The surface porosity determined using AFM was much lesser than the internal porosity determined using weight analysis. The pore diameters on the inner and outer surfaces of the CTA Membranes determined using AFM were much lesser than pore diameter calculated on the basis of the permeability data. We conclude that the CTA Dialysis Membrane, which is generally regarded as a homogeneous Membrane, is actually a multilayer Membrane. The CTA Dialysis Membrane has tight layers at the inner and outer surfaces, and has a loose layer inside the Membrane.

  • Membrane potential and charge density of hollow-fiber Dialysis Membranes
    Journal of Membrane Science, 2010
    Co-Authors: Ken-ichiro Yamamoto, Masato Matsuda, Taiji Yakushiji, Takehiro Miyasaka, Takehito Ogawa, Akinori Iino, Kiyotaka Sakai
    Abstract:

    Abstract Membrane charge affects diffusive permeability for ions. Hence, evaluation of Membrane charge density is necessary to clarify diffusive permeability for ions. The objective of the present study is to measure stable and reproducible Membrane potentials with hollow-fiber Membranes and to evaluate the electrostatic characteristics of Dialysis Membrane by applying Membrane potential measurement method for flat Membrane to hollow-fiber Membranes. Membrane charge density was calculated from data on the Membrane potential. Values for Membrane charge density obtained as electrostatic characteristics of AM-UP150 (regenerated cellulose), KF-15C (ethylenevinylalcohol copolymer), PAN-150SF (polyacrylonitrile), AM-BC150X (polyethylene glycol-modified regenerated cellulose), FB-150U (cellulose triacetate), APS-150E (polysulfone), FLX-15GW (polyester–polymer alloy) and BLF-10GW (diethylaminoethyl-modified regenerated cellulose) were −0.9, −0.9, −0.7, −0.5, −0.1, +0.1, +0.35 and +3.1 mol/m 3 , respectively. This method allows determination of the Membrane charge density of hollow-fiber Dialysis Membrane.

  • Nanotechnological characterization of human serum albumin adsorption on wet synthetic polymer Dialysis Membrane surfaces.
    ASAIO journal (American Society for Artificial Internal Organs : 1992), 2009
    Co-Authors: Koki Namekawa, Makoto Fukuda, Ken-ichiro Yamamoto, Masato Matsuda, Yutaka Yagi, Kiyotaka Sakai
    Abstract:

    The objective of the present study was to evaluate the characteristics of protein adsorption on the inner surface of various Dialysis Membranes, to develop protein adsorption-resistant biocompatible Dialysis Membranes. The adsorption force of human serum albumin (HSA) on the inner surface of a Dialysis Membrane and the smoothness of the Membrane were evaluated from a nanoscale perspective by atomic force microscopy. The content ratio of the hydrophilic polymer, polyvinylpyrrolidone (PVP), was determined by attenuated total reflection Fourier transform infrared spectroscopy. Nine synthetic-polymer Dialysis Membranes on the market made of polysulfone (PSF), polyethersulfone (PES), polyester polymer-alloy (PEPA), and ethylene vinylalcohol (EVAL) were used in the present study. The HSA adsorption force on the surface of the hydrophobic polymer PEPA Membrane was higher than that on the hydrophilic polymer EVAL Membrane surface. It has been considered beneficial, for decreasing the HSA adsorption force, to cover a hydrophobic polymer Membrane surface with PVP. However, there were some areas on PVP-containing Membrane surfaces at which much higher HSA adsorption forces were observed. The HSA adsorption force gave a nearly linear correlation with the surface roughness on the PSF Membrane surface. However, the HSA adsorption force was uncorrelated with the PVP content ratio for any of the PSF Membrane surfaces tested. In conclusion, protein adsorption can be minimized by the use of Dialysis Membranes made of hydrophobic polymers containing PVP with a smooth surface.

  • Effects of fluid flow on elution of hydrophilic modifier from Dialysis Membrane surfaces
    Journal of Artificial Organs, 2008
    Co-Authors: Masato Matsuda, Hiroki Sakata, Takahisa Ogawa, Mika Sato, Makoto Fukuda, Ken-ichiro Yamamoto, Taiji Yakushiji, Takehiro Miyasaka, Kiyotaka Sakai
    Abstract:

    When uremic blood flows through dialyzers during hemoDialysis, Dialysis Membrane surfaces are exposed to shear stress and internal filtration, which may affect the surface characteristics of the Dialysis Membranes. In the present study, we evaluated changes in the characteristics of Membrane surfaces caused by shear stress and internal filtration using blood substitutes: water purified by reverse osmosis and 6.7 wt% dextran70 solution. We focused on the levels of a hydrophilic modifier, polyvinylpyrrolidone (PVP), on the Membrane surface measured by attenuated total reflectance Fourier transform infrared spectroscopy. Experiments involving 4 h Dialysis, 0–144 h shear-stress loading, and 4 h dead-end filtration were performed using polyester-polymer alloy (PEPA) and polysulfone (PS) Membranes. After the Dialysis experiments with accompanying internal filtration, average PVP retention on the PEPA Membrane surface was 93.7% in all areas, whereas that on the PS Membrane surface was 98.9% in all areas. After the shear-stress loading experiments, PVP retention on the PEPA Membrane surface decreased as shear-stress loading time and the magnitude of shear stress increased. However, with the PS Membrane, PVP retention scarcely changed. After the dead-end filtration experiments, PVP retention decreased in all areas for both PEPA and PS Membranes, but PVP retention on the PEPA Membrane surface was lower than that on the PS Membrane surface. PVP on the PEPA Membrane surface was eluted by both shear stress and internal filtration, while that on the PS Membrane surface was eluted only by internal filtration.

  • Nanotechnological evaluation of protein adsorption on Dialysis Membrane surface hydrophilized with polyvinylpyrrolidone
    Journal of Membrane Science, 2007
    Co-Authors: Masato Matsuda, Makoto Fukuda, Ken-ichiro Yamamoto, Taiji Yakushiji, Takehiro Miyasaka, Kiyotaka Sakai
    Abstract:

    Hydrophilizing synthetic polymer Dialysis Membranes with polyvinylpyrrolidone (PVP) play an important role for inhibition of protein adsorption on Membrane surface. In the present study, the effect of PVP on protein adsorption was evaluated from a nano-scale perspective. Swelling behavior of PVP present on wet polysulfone (PS)/PVP film surfaces was observed by atomic force microscopy (AFM). Fibrinogen and human serum albumin (HSA) were immobilized on the tip of AFM probes, with which a force-curve between protein and wet PS/PVP film surface was measured by AFM while scanning in order to visualize two-dimensional protein adsorbability on film surfaces. Furthermore, HSA adsorbability on non-PVP containing PEPA Dialysis Membrane (FLX-15GW) and PVP containing PEPA Dialysis Membrane (FDX-150GW) was evaluated by the AFM force-curve method. As a result, PS/PVP film surface was completely covered with hydrated and swollen PVP at 5 wt% or more PVP content. Protein adsorbability on PS/PVP film surfaces decreased greatly with increasing content of PVP. The adsorption of HSA was inhibited by the presence of PVP on film surfaces more significantly than that of more hydrophobic fibrinogen. HSA adsorbability on wet FLX-15GW Dialysis Membrane surface was 428 ± 174 pN whereas that on wet FDX-150GW Dialysis Membrane surface was 42 ± 29 pN.

Alan T Branco - One of the best experts on this subject based on the ideXlab platform.

Beatriz Dos Santos Ferreira - One of the best experts on this subject based on the ideXlab platform.

Masahiro Kudo - One of the best experts on this subject based on the ideXlab platform.

  • Estimation of protein adsorption on Dialysis Membrane by means of TOF-SIMS imaging
    Journal of Membrane Science, 2004
    Co-Authors: Satoka Aoyagi, Kiyotaka Sakai, Masayo Hayama, Urara Hasegawa, Miyako Tozu, Takahiro Hoshi, Masahiro Kudo
    Abstract:

    Abstract Protein adsorption on Dialysis Membrane was studied by time-of-flight secondary ion mass spectrometry (TOF-SIMS), which is expected to be capable of chemical imaging of insulated samples, such as hollow-fiber Dialysis Membranes. Three commercially available hollow-fiber Dialysis Membranes having different pore sizes and structures, were tested in the present study. Bovine serum albumin (BSA) solutions were used to adsorb the protein on the samples. TOF-SIMS images and spectra of native Membranes and Membranes treated with BSA were compared in order to identify secondary ions related to BSA and Membranes. Mutual information, one of applications of information theory, was employed to select fragment ions related to BSA. TOF-SIMS images show distribution of adsorbed BSA on the Dialysis Membranes and indicate that BSA permeability and interaction between the Membranes and BSA definitely depend on pore size, structure and material.

  • TOF-SIMS imaging of protein adsorption on Dialysis Membrane
    Applied Surface Science, 2004
    Co-Authors: Satoka Aoyagi, Kiyotaka Sakai, Urara Hasegawa, Takahiro Hoshi, Msayo Hayama, Masahiro Kudo
    Abstract:

    Abstract Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is capable of chemical imaging of proteins on insulated samples such as hollow-fiber Dialysis Membranes. Albumin loss and a lowering of diffusive permeability caused by protein adsorption on Dialysis Membranes should be reduced in order to enhance Dialysis adequacy of the patients. Bovine serum albumin (BSA)-adsorbed hollow-fiber Dialysis Membranes were tested in the present study. TOF-SIMS images and spectra of both native Membranes and BSA-adsorbed Membranes were compared in order to identify secondary ions related to BSA and Membranes. Peaks of secondary ions related to BSA and each Membrane were selected by means of information theory, and they are characterized by principal component analysis (PCA). Chemical images of BSA adsorption on both native and treated Membranes were obtained to find that BSA permeability and interaction between the Membranes and BSA definitely depend on the properties of a Membrane. TOF-SIMS imaging obtained with information theory is a powerful tool to estimate protein adsorption on the Dialysis Membranes.