Kazuyuki Sugita

Preparation of hydrophilic amidoxime fibers by cografting acrylonitrile and methacrylic acid from an optimized monomer composition

Abstract To improve the adsorption rate of uranium from seawater, hydrophilic amidoxime (AO) fibers were prepared by cografting of methacrylic acid (MAA) with acrylonitrile (AN) onto polypropylene fibers and subsequent conversion of the produced cyano group to an amidoxime group by reaction with hydroxylamine. An optimum amidoximation time of 0.75 h was selected at a weight ratio of AN to MAA (x/y) of 80/20. By varying x/y in the monomer mixture, cografted polymers were prepared. The value of x/y governed the AO group density and water content of the resultant fibrous adsorbents. As x/y increased, the AO group density of the fiber increased and its water content decreased. The AO/MAA adsorbent, based on the PP fibers prepared by cografting at an x/y of 60/40 and subsequent amidoximation, exhibited the highest uranium adsorption rate in the flow-through mode.

Chiral separation of dl-tryptophan using porous membranes containing multilayered bovine serum albumin crosslinked with glutaraldehyde

Bovine serum albumin (BSA) as a chiral ligand was captured uniformly throughout a porous hollow-fiber membrane at a level of 160 mg/g by the polymer chains grafted onto the membrane. BSA was bound in three layers with an end-on orientation to diethylamino groups on the graft chains which expanded from the pore surface towards the pore interior due to mutual electrostatic repulsion. Subsequently, crosslinking of BSA with a 0.025% (w/w) of glutaraldehyde in a Tris-HCl buffer (pH 8) for 4 h was effective in stabilizing the amount of BSA immobilized at a level of 150 mg/g. A solution of DL-tryptophan in a Tris-HCl buffer as a mobile phase permeated the crosslinked-BSA multilayered membrane and produced a chromatogram with a separation factor of 12. BSA leakage was not detected in the mobile phases at various pH values and organic modifiers.

Radiation-induced graft polymerization is the key to develop high-performance functional materials for protein purification

We have described a preparation scheme for immobilizing polymer chains at a uniformly high density onto a microfiltration membrane. Highly efficient protein recovery was demonstrated by the results of the determination of breakthrough and elution curves. The three requirements of high rate, high capacity, and repeated use for the protein recovery were satisfied by ensuring the occurrence of convection, multilayer binding, and hydrophilization, respectively. In addition, easy scale-up to fabrication of a membrane module was verified on a small scale.

Multilayer binding of proteins to polymer chains grafted onto porous hollow-fiber membranes containing different anion-exchange groups.

Various anion‐exchange groups were introduced into the polymer chains grafted onto a porous hollow‐fiber membrane for protein recovery by radiation‐induced graft polymerization and subsequent functionalization of a monomer containing an epoxy group. The graft chains extended from the pore surface toward the pore interior, resulting in the multilayer binding of proteins to the graft chains. Combinations of three anion‐exchange groups, namely, amino (AM), ethylamino (EA), and diethylamino (DEA) groups, and three proteins, namely, β‐lactoglobulin, bovine serum albumin, and urease, were examined to evaluate the degree of multilayer binding of protein to the graft chains in the permeation mode. Multilayer binding was observed for hollow‐fiber membranes containing EA and DEA groups, with conversions of epoxy groups to EA or DEA groups of higher than 80%. The amount of adsorbed protein remained constant irrespective of the conversion for the hollow‐fiber membrane containing an AM group. The dependence of the flux on the conversion was consistent with that of the degree of multilayer binding to the graft chains.

Preparation of a hydrophobic porous membrane containing phenyl groups and its protein adsorption performance

A novel porous membrane was prepared by radiation-induced graft polymerization of an epoxy-group-containing vinyl monomer, glycidyl methacrylate, and subsequent addition of phenol and water. A phenyl group was appended to the polymer chain grafted on to a porous polyethylene hollow-fibre membrane. The presence of a diol group together with the phenyl group was required to reduce non-selective adsorption of the protein. A bovine serum albumin (BSA) phosphate buffer solution containing 2 M ammonium sulfate was forced to permeate through the resultant hydrophobic porous membrane, 0.36 mm thick with a phenyl-group density of 1.3 mmol/g. The breakthrough curves of BSA overlapped independent of the residence time in the range 12–1.2 s because of negligible diffusional mass-transfer resistance. A lower phenyl-group density resulted in a higher recovery of BSA after a series of adsorption and elution steps.

Comparison of protein adsorption by anion-exchange interaction onto porous hollow-fiber membrane and gel bead-packed bed

Protein collection performance by anion-exchange interaction was compared between a single porous hollow-fiber membrane and a gel bead-packed bed under identical conditions from a viewpoint of flow resistance and breakthrough behavior. At a space velocity (SV) of 100 h−1, an ethanolamino-group-containing porous hollow-fiber membrane (EA-C fiber) exhibited the same dynamic binding capacity for bovine serum albumin as a bed charged with diethylaminoethyl-group-containing gel beads (DEAE-G bed). Because mass transfer of the protein was enhanced by convective flow of the protein solution through the pores of the EA-C fiber, the EA-C fiber exhibited a higher productivity than the DEAE-G bed over SV = 100 h−1.

Ionic crosslinking of SO3H-group-containing graft chains helps to capture lysozyme in a permeation mode

Abstract SO 3 H-group-containing polymer chains were grafted onto a porous hollow-fiber membrane uniformly across the thickness of the membrane (about 0.9 mm) by radiation-induced graft polymerization of glycidyl methacrylate and subsequent reaction with sodium sulfite. The graft chains extended from the pore surface due to their mutual electrostatic repulsion, and were crosslinked with bivalent ions such as Mg 2+ and Ca 2+ , resulting in an increase in permeation rate of the liquid through the pores. Lysozyme was bound in multilayers to the SO 3 H-group-containing graft chains, which had been previously crosslinked with Mg ions, and the permeation rate was increased with the progression of lysozyme binding based on the ion-exchange interaction with Mg ions.

Module performance of anion-exchange porous hollow-fiber membranes for high-speed protein recovery

Abstract A laboratory-scale module was fabricated by housing eight anion-exchange porous hollow-fiber membranes with an effective length of 8 cm in parallel to each other in a cartridge. The hollow fibers were prepared by radiation-induced graft polymerization of glycidyl methacrylate and subsequent chemical modifications using diethylamine and ethanolamine. The resultant hollow fibers had diethylamino and ethanolamino group densities of 2.1 and 1.2 mmol/g of the dry hollow fiber, respectively, with inner and outer diameters of 2.8 and 4.4 mm, respectively, in a wet state. A low operating pressure of 0.1 MPa in the module provided a flow-rate of 100 ml/min for a bovine serum albumin solution. The dynamic binding amount of bovine serum albumin for the module was 270 mg, irrespective of the flow-rate, for rates ranging from 10 to 100 ml/min. The dynamic binding amount for the module was equivalent to eight times that of a single hollow fiber with an identical effective length, which indicates a linear relationship between the module and the number of single fibers for dynamic binding amount.

Selection of a precursor monomer for the introduction of affinity ligands onto a porous membrane by radiation-induced graft polymerization

A scheme for the coupling of a ligand onto a porous membrane was selected based on criteria of permeability of liquid and adsorptivity of protein. Two precursor monomers, i.e., acrylic acid (AAc) and glycidyl methacrylate (GMA), were grafted onto a porous polyethylene hollow fibre by radiation-induced graft polymerization. The carboxyl group of the AAc-grafted hollow fibre was reacted with N-hydroxysuccinimide to produce a succinimide group as an activated group. The resultant hollow fibre had a significantly lower liquid flux than the original hollow fibre, whereas the GMA-grafted hollow fibre retained its original level of liquid permeability when the epoxy group as the activated group was introduced at a sufficiently high density.

Composition and Crystallinity of Electroless Nickel

On montre que les depots de Ni obtenus sont cristallins pour pH≥9,4 et pour une concentration du bain en Na 2 H 2 PO 2 de 25 g/l, mais aussi pour des concentrations de pyrophosphate de 35 g/h et le pH=10