Publications by authors named "Ken Terao"

15 Publications

  • Page 1 of 1

Complex Formation of Silica Nanoparticles with Collagen: Effects of the Conformation of Collagen.

Langmuir 2020 12 16;36(47):14425-14431. Epub 2020 Nov 16.

Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1, Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.

Negatively charged Ludox silica nanoparticles (SiNPs) form a complex with atelocollagen (AC) in acidic buffers (pH = 4 or 3). AC is a low-immunogenic derivative of collagen obtained by the removal of N- and C-terminal telopeptide components. Mixed solutions of negatively charged SiNPs and AC were turbid, while positively charged SiNPs (Ludox CL) did not form a complex with AC in pH 4 buffer, indicating that electrostatic attraction is the dominant force to form the complex. Small-angle X-ray scattering (SAXS) and circular dichroism (CD) measurements were made for AC and Ludox LS (or CL) solutions in acetate buffer (pH 4.0) and citrate buffer (pH 3.0). The CD data showed that the stability of the triple helical structure of AC in the buffers is not affected by the complexation. The resulting complex consisting of triple helical AC and SiNPs did not influence the SAXS profile except for the lowest region investigated. On the contrary, different scattering profiles were observed for the single chain AC and SiNP mixture indicating densely packed SiNPs in the complex. This scattering behavior was fairly explained in terms of the sticky hard sphere model (SHSM). This AC conformation-dependent complexation may be because of the hydrogen bonding interaction between the single chain AC and SiNPs. The temperature-induced change of the complex formation can be applied for thermoresponsive hybrid materials.
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http://dx.doi.org/10.1021/acs.langmuir.0c02867DOI Listing
December 2020

Self-Assembly of Amphiphilic Amylose Derivatives in Aqueous Media.

Langmuir 2019 05 13;35(20):6719-6726. Epub 2019 May 13.

Department of Macromolecular Science, Graduate School of Science , Osaka University , 1-1, Machikaneyama-cho , Toyonaka , Osaka 560-0043 , Japan.

Six amylose derivative (CCMA) samples with hydrophobic dodecyl ether groups and hydrophilic sodium carboxymethyl groups were synthesized from an enzymatically synthesized amylose for which the weight-average molar mass is 50 kg mol to realize amylose-based amphiphilic polymer micelles. The degree of substitution of hydrophobic (DS) and hydrophilic (DS) groups ranges between 0.076 and 0.39 and between 0.35 and 1.83, respectively. Static and dynamic light scattering, small-angle X-ray scattering (SAXS), and fluorescence measurements with pyrene as a probe were carried out for the samples in 150 mM aqueous NaCl to characterize the higher-order structure in solution. The fluorescence from pyrene showed that all six samples have hydrophobic environment, while the hydrophobicity tends to increase with rising DS. All six samples have high scattering intensity owing to the relatively large concentrated droplets ranging in the hydrodynamic radius from 50 to 110 nm, whereas the weight fraction of such large particles is substantially small except for the highest DS sample. Most polymer chains for relatively low DS of 0.076 were molecularly dispersed with a very small amount of large droplets. The dispersed chain has a slightly smaller helix pitch per residue and a more rigid main chain than those for amylose in dimethyl sulfoxide, suggesting that the amylosic main chain of CCMA has a helical structure with dodecyl groups at least locally. On the other hand, an anisotropic shaped micelle-like structure is only found for relatively high DS (0.23 and 0.39) samples, which was detected by the SAXS profile at a high scattering vector range. The micelle structure for high DS samples is consistent with the high chain stiffness.
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http://dx.doi.org/10.1021/acs.langmuir.9b00985DOI Listing
May 2019

Does local chain conformation affect the chiral recognition ability of an amylose derivative? Comparison between linear and cyclic amylose tris(3,5-dimethylphenylcarbamate).

J Chromatogr A 2019 Aug 10;1599:144-151. Epub 2019 Apr 10.

Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan. Electronic address:

Coated-type chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC) were prepared from three cyclic amylose tris(3,5-dimethylphenylcarbamate) (cADMPC) samples, of which weight-average molar mass (M) ranges from 19 to 91 kg mol, and from three linear ADMPC samples ranging in M from 25 to 90 kg mol. CSPs made of cADMPC showed appreciably different chiral separation ability comparing with those for ADMPC with a mixed eluent of n-hexane and 2-propanol. Local conformation plays an important role for the chiral separation taking into account that the local helical structure of cADMPC in dilute solution is extended comparing with ADMPC. Immobilized-type CSPs were also prepared from enzymatically synthesized linear and cyclic amylose samples with 3-(triethoxysilyl)propylcarbamate linkers (ADMPCi and cADMPCi) of which M's are in the range from 18 to 130 kg mol. When we choose quite high linker contents, CSPs of cADMPCi were fairly close to those of ADMPCi. This suggests that local conformations of ADMPCi and cADMPCi are similar in the stationary phase since they are crosslinked to the other polymer chains with multiple points on the polymer chain.
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http://dx.doi.org/10.1016/j.chroma.2019.04.019DOI Listing
August 2019

Colloidal Dispersion of a Perfluorosulfonated Ionomer in Water⁻Methanol Mixtures.

Polymers (Basel) 2018 Jan 14;10(1). Epub 2018 Jan 14.

Department of Macromolecular Science, Osaka University, Toyonaka Osaka 560-0043, Japan.

We have investigated the dispersion state of a perfluorosulfonated ionomer (PFSI; Nafion) in aqueous dispersion and the effect of methanol (MeOH) added to the aqueous dispersion by small-angle X-ray scattering (SAXS) as well as static and dynamic light scattering (SLS and DLS, respectively). Although both electrostatic and hydrophobic interactions of PFSI are expected to be strong in the dispersions, SAXS profiles obtained were satisfactorily fitted by the spherical particle model of a bimodal molar mass distribution. The rod-like aggregate model proposed in previous papers was denied at least for the present PFSI dispersion. Although the SAXS profiles exhibited a weak peak and the auto-correlation functions of DLS showed a log-time decay by the "repulsive cage effect" due to the long-ranged electrostatic interaction among PFSI particles, the concentration dependence of SLS results was probably normal because the cancellation of the electrostatic and hydrophobic interactions. The addition of MeOH into the aqueous dispersion of PFSI weakened both the hydrophobic and electcrostatic interactions of PFSI, and it is rather difficult to classify whether MeOH is a good or poor solvent (dispersant) for PFSI.
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http://dx.doi.org/10.3390/polym10010072DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6414853PMC
January 2018

Structural Analysis of Hydrophobe-Uptake Micelle of an Amphiphilic Alternating Copolymer in Aqueous Solution.

Langmuir 2016 08 29;32(31):7875-81. Epub 2016 Jul 29.

Department of Macromolecular Science, Osaka University , 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.

We investigated the structure of the hydrophobe-uptake micelle of an alternating amphiphilic copolymer in aqueous solutions, by combining light scattering and small-angle X-ray scattering (SAXS). When the copolymer micelle includes the hydrophobe (1-dodecanol), the unicore flower micelle transforms into the multicore flower necklace, and the flower necklace is slightly stiffer than the hydrophobe-free flower necklace of the same copolymer. Moreover, the hydrophobe is included not in the hydrophobic core region but in the intermingled region of the hydrophobic group and the loop chain of the unit flower micelle. Therefore, the structure of the hydrophobe-uptake micelle of the amphiphilic alternating copolymer is quite different from that of hydrophobe-uptake spherical micelles of low molar mass surfactants and of amphiphilic block copolymers, where the hydrophobe is included in the hydrophobic region of the micelles.
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http://dx.doi.org/10.1021/acs.langmuir.6b01480DOI Listing
August 2016

Conformational change from rigid rod to star: a triple-helical peptide with a linker domain at the C-terminal end.

J Phys Chem B 2015 Mar 23;119(9):3714-9. Epub 2015 Feb 23.

Department of Macromolecular Science, Osaka University , 1-1, Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.

Small-angle X-ray scattering and circular dichroism measurements were made for a triple-helical peptide of which one end was linked by the thermally stable trimerization domain of type XIX collagen. The radius of gyration decreased steeply around the transition temperature while the scattering intensity at zero angle did not significantly change, indicating no molar mass change through the conformational transition. Thus, the data were analyzed in terms of the rigid cylinder model for the data at low temperatures and the wormlike star model at high temperatures. It was confirmed that the peptide molecules behave as a rod-like cylinder at low temperature and a semi flexible three-arm star-like chain at high temperature of which the single-coil peptide chain is appreciably extended by the high segment density nearby the linking domain.
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http://dx.doi.org/10.1021/jp5129172DOI Listing
March 2015

Local conformation and intermolecular interaction of rigid ring polymers are not always the same as the linear analogue: cyclic amylose tris(phenylcarbamate) in Θ solvents.

J Phys Chem B 2013 Aug 5;117(32):9576-83. Epub 2013 Aug 5.

Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.

Small-angle X-ray scattering and static and dynamic light scattering measurements were made for cyclic amylose tris(phenylcarbamate) (cATPC) of which weight-average molar mass M(w) ranges from 1.3 × 10(4) to 1.5 × 10(5) to determine their z-average mean square radius of gyration z, particle scattering function P(q), hydrodynamic radius R(H), and second virial coefficient A2 in methyl acetate (MEA), ethyl acetate (EA), and 4-methyl-2-pentanone (MIBK). The obtained z, P(q), and R(H) data were analyzed in terms of the wormlike ring to estimate the helix pitch per residue h and the Kuhn segment length λ(-1) (the stiffness parameter, twice the persistence length). Both h and λ(-1) for cATPC in MEA, EA, and MIBK are smaller than those for linear amylose tris(phenylcarbamate) (ATPC) in the corresponding solvent and the discrepancy becomes more significant with increasing the molar volume of the solvent. This indicates that not every rigid ring has the same local helical structure and chain stiffness as that for the linear polymer in the M(w) range investigated while infinitely long ring chains should have the same local conformation. This conformational difference also affects A2. In actuality, negative A2 was observed for cATPC in MIBK at the Θ temperature of linear ATPC whereas intermolecular topological interaction of ring polymers increases A2.
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http://dx.doi.org/10.1021/jp406607wDOI Listing
August 2013

Side-chain-dependent helical conformation of amylose alkylcarbamates: amylose tris(ethylcarbamate) and amylose tris(n-hexylcarbamate).

J Phys Chem B 2012 Oct 16;116(42):12714-20. Epub 2012 Oct 16.

Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.

Eight amylose tris(ethylcarbamate) (ATEC) samples ranging in the weight-average molar mass M(w) from 1.0 × 10(4) to 1.1 × 10(6) g mol(-1) and five amylose tris(n-hexylcarbamate) (ATHC) samples of which M(w) varies from 4.9 × 10(4) to 2.2 × 10(6) g mol(-1) have been prepared from enzymatically synthesized amylose samples having narrow dispersity indices and no branching. Small-angle angle X-ray scattering (SAXS), light scattering, viscometry, and infrared (IR) absorption measurements were carried out for their dilute solutions, that is, ATEC in tetrahydrofuran (THF), 2-methoxyethanol (2ME), methanol (MeOH), and ATHC in THF and 1-propanol (1PrOH) to determine M(w), particle scattering functions, intrinsic viscosities, and IR spectra. SAXS and viscosity measurements were also made on ATEC in d- and l-ethyl lactates. The data were analyzed in terms of the wormlike cylinder model to estimate the helix pitch (or contour length) per residue h and the Kuhn segment length λ(-1) (stiffness parameter, twice the persistence length). Both ATEC and ATHC have large λ(-1) in THF, that is, 33 and 75 nm, respectively, and smaller λ(-1) were obtained in alcohols, indicating that they have rigid helical conformation stabilized by intramolecular hydrogen bonds in THF. On the contrary, the helical structure estimated from the h value significantly depends on the alkyl side groups in a complex fashion, that is, h = 0.36 nm for ATEC, h = 0.29 nm for ATHC, and h = 0.26 nm for amylose tris(n-butylcarbamate) (ATBC). This is likely related to the bulkiness of side groups packed inside the amylosic helices. The solvent dependence of h, λ(-1), and the fraction f(hyd) of intramolecular hydrogen bonds for ATEC can be explained by a current model as is the case with ATBC [ Terao , K. ; Macromolecules 2010 , 43 , 1061 ], in which each contour point along the chain takes loose helical and rigid helical sequences independently.
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http://dx.doi.org/10.1021/jp307998tDOI Listing
October 2012

Solvent-dependent conformation of a regioselective amylose carbamate: amylose-2-acetyl-3,6-bis(phenylcarbamate).

Biopolymers 2012 Dec;97(12):1010-7

Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.

Six amylose-2-acetyl-3,6-bis(phenylcarbamate) (AAPC) samples ranging in weight-average molar mass M(w) from 1.8 × 10(4) g mol(-1) to 1.1 × 10(6) g mol(-1) have been prepared from enzymatically synthesized amylose samples. Static light scattering, small-angle X-ray scattering, sedimentation equilibrium, and viscosity measurements were made for the samples in 1,4-dioxane (DIOX), 2-ethoxyethanol (2EE), and 2-butanone (MEK) all at 25°C to determine particle scattering functions, z-average radii of gyration, intrinsic viscosities, as well as M(w). The data were analyzed in terms of the wormlike cylinder model mainly to yield the helix pitch per residue h and the Kuhn segment length λ(-1), which corresponds to twice of the persistence length. The latter parameters (λ(-1)) in 2EE (11 nm) and MEK (12 nm) are quite smaller than those for amylose tris(phenylcarbamate) (ATPC) in the same solvent (16 nm in 2EE and 18 nm in MEK) whereas those for AAPC (21 nm) and ATPC (22 nm) in DIOX are essentially the same as each other. This indicates that the chain stiffness of AAPC is more strongly influenced by the solvents since the number of intramolecular H-bonds of AAPC is more changeable than that for ATPC.
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http://dx.doi.org/10.1002/bip.22118DOI Listing
December 2012

Solvent-dependent conformation of amylose tris(phenylcarbamate) as deduced from scattering and viscosity data.

Biopolymers 2009 Sep;91(9):729-36

Department of Macromolecular Science, Osaka University, 1-1, Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan.

The z-average mean-square radius of gyration S(2)(z), the particle scattering function P(k), the second virial coefficient, and the intrinsic viscosity [eta] have been determined for amylose tris(phenylcarbamate) (ATPC) in methyl acetate (MEA) at 25 degrees C, in ethyl acetate (EA) at 33 degrees C, and in 4-methyl-2-pentanone (MIBK) at 25 degrees C by light and small-angle X-ray scattering and viscometry as functions of the weight-average molecular weight in a range from 2 x 10(4) to 3 x 10(6). The first two solvents attain the theta state, whereas the last one is a good solvent for the amylose derivative. Analysis of the S(2)(z), P(k), and [eta] data based on the wormlike chain yields h (the contour length or helix pitch per repeating unit) = 0.37 +/- 0.02 and lambda(-1) (the Kuhn segment length) = 15 +/- 2 nm in MEA, h = 0.39 +/- 0.02 and lambda(-1) = 17 +/- 2 nm in EA, and h = 0.42 +/- 0.02 nm and lambda(-1) = 24 +/- 2 nm in MIBK. These h values, comparable with the helix pitches (0.37-0.40 nm) per residue of amylose triesters in the crystalline state, are somewhat larger than the previously determined h of 0.33 +/- 0.02 nm for ATPC in 1,4-dioxane and 2-ethoxyethanol, in which intramolecular hydrogen bonds are formed between the C==O and NH groups of the neighbor repeating units. The slightly extended helices of ATPC in the ketone and ester solvents are most likely due to the replacement of those hydrogen bonds by intermolecular hydrogen bonds between the NH groups of the polymer and the carbonyl groups of the solvent.
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http://dx.doi.org/10.1002/bip.21219DOI Listing
September 2009

Circular dichroism of optically active poly(dialkylsilane) aggregates in microcapsules.

Langmuir 2006 Sep;22(19):7975-80

Department of Biological and Chemical Engineering, Faculty of Engineering, Gunma University, 1-5-1 Tenjin-cho, Kiryu 376-8515, Japan.

Poly[n-hexyl-(S)-3-methylpentylsilane] aggregates confined in microcapsules to keep the aggregation number and ranging in average polymer mass m(p) in a microcapsule from 2 x 10(-)(16) to 2 x 10(-)(14) g were studied by circular dichroism measurements in ethanol (a nonsolvent) and tetrahydrofuran (an associative solvent at low temperature) at various temperatures. The weight-average molecular weight M(w) and the polydispersity index (the ratio of M(w) to the number-average molecular weight) of the polysilane sample were 6.6 x 10(4) and 1.07, respectively, and the average number of polymer molecules in each capsule was estimated to be 1.9 x 10(3) for m(p) = 2 x 10(-)(16) g and 1.7 x 10(5) for m(p) = 2 x 10(-)(14) g. The size of each aggregate did not affect the optical activity because the circular dichroism thus obtained was proportional to m(p) under the same conditions in the investigated m(p) range; on the other hand, the peak height of the circular dichroism in tetrahydrofuran had a significant hysteresis between 0 and 25 degrees C. Moreover, the circular dichroism appreciably reflected the prepared method, that is, the temperature and solvent; in other words, the aggregates memorized the initial conditions in their stacking structures.
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http://dx.doi.org/10.1021/la060810+DOI Listing
September 2006

Preparation and characterization of core-shell nanoparticles hardened by gamma-ray.

Colloids Surf B Biointerfaces 2004 Nov;38(3-4):187-90

Department of Biological and Chemical Engineering, Faculty of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan.

Core-shell nanoparticles have been prepared by irradiation of gamma-ray on block copolymer micelles consisting of hydrophilic polyacrylic acid and hydrophobic polyisoprene with each 40 monomer units. The structure was determined by means of dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and atomic force microscopy (AFM). The size distribution of the core-shell nanoparticles determined by DLS and AFM was very narrow. The average diameter of the particles decreased from 48 nm for the original micelles to 26 nm by the irradiation of 30 kGy. The core size determined by SAXS combined with DLS was roughly constant of 10 nm, irrespective of irradiation dose, whereas the shell thickness of the micelles was twice as large as the core size, and decreased with increasing irradiation dose.
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http://dx.doi.org/10.1016/j.colsurfb.2004.02.021DOI Listing
November 2004

Single-particle light scattering study of polyethyleneglycol-grafted poly(ureaurethane) microcapsule in ethanol.

Colloids Surf B Biointerfaces 2004 Sep;37(3-4):129-32

Department of Biological and Chemical Engineering, Faculty of Engineering, Gunma University, 1-5-1, Tenjin-cho, Kiryu, 376-8515, Japan.

Microcapsules having polyethyleneglycol-grafted poly(ureaurethane) (PUU) membrane and di-2ethylhexyl phthalate core have been prepared, and the structure when they were suspended in dispersing ethanol have been studied by means of single-particle light scattering method. The PUU membrane was synthesized from monomers with aromatic functional groups (microcapsule MC110) and hexamethylene functional groups (microcapsule MC160). Because the outer and inner solvent passed through the membrane easily, the outside and inside of the membrane were the same at the equilibrium state. The thickness of the wall membrane was significantly smaller than that calculated from the overall weight ratio of the wall-forming material and the core solvents. It was attributed to low affinity of PUU membranes and ethanol.
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http://dx.doi.org/10.1016/j.colsurfb.2004.07.008DOI Listing
September 2004

Reagent-free crosslinking of aqueous gelatin: manufacture and characteristics of gelatin gels irradiated with gamma-ray and electron beam.

J Biomater Sci Polym Ed 2003 ;14(11):1197-208

Department of Biological and Chemical Engineering, Faculty of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan.

In order to obtain a gelatin hydrogel crosslinked by a reagent-free method, gamma-ray and electron beam radiation was applied to porcine, bovine and fish gelatin gels and the products were characterized by measuring the gel fraction, the swelling ratio and the enzymatic degradability. On increasing the radiation dose, the gel fraction increased and both the swelling ratio and the enzymatic degradability decreased. The transition temperature from gel to sol of the hydrogel containing more than 5% mammal gelatins increased up to more than 90 degrees C when gamma-ray or electron beam were irradiated by more than 10 kGy. The results show that the degree of crosslinking of irradiated gelatin hydrogels increases with increasing irradiation dose and with decreasing concentration. It is suggested that the radiation crosslinking occurs around the physical crosslinking point or multiple helix structure of gelatin gel.
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http://dx.doi.org/10.1163/156856203322553437DOI Listing
September 2004
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