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Papers by Toshiyuki Takano

Macromolecules, Apr 10, 2020

Nucleation and Atmospheric Aerosols, 2022

Holzforschung, Feb 1, 2010

Journal of Wood Chemistry and Technology, Sep 1, 2006

Journal of Wood Chemistry and Technology, Apr 1, 2008

Cellulose, Oct 14, 2005

Novel cellobiose and cellulose (DP n =ca. 30) derivatives, N-(1-pyrenebutyloyl)-4-O-(β-d-glucopyr... more Novel cellobiose and cellulose (DP n =ca. 30) derivatives, N-(1-pyrenebutyloyl)-4-O-(β-d-glucopyranosyl)-β-d-glucopyranosylamine (6), N-(15-(1-pyrenebutyloylamino)-pentadecanoyl)-4-O-(β-d-glucopyranosyl)-β-d-glucopyranosylamine (7), N-(1-pyrenebutyloyl)-β-cellulosylamine (13), N-(15-(1-pyrenebutyloylamino)-pentadecanoyl)-β-cellulosylamine (14) carrying a pyrene group as a single fluorescent probe at the reducing end, were prepared in order to investigate their self-assembly systems in solutions. The relative intensity of the excimer emission at ca. 480 nm due to dimerized pyrenes (intensity I E) to the monomer emission at ca. 380 nm due to isolated pyrene (intensity I M), i.e., I E/I M, was monitored in various solutions. In water/dimethyl sulfoxide (DMSO) mixed solvent (0–98%, v/v), the ratio I E/I M remained low (0.04) for compound 6 over the range of water concentrations, indicating that pyrenes at C-1 position of compound 6 were diffused. On the other hand, the ratio I E/I M increased (0.04–4.96) for compound 7 with the increase in water concentration, indicating that pyrenes at C-1 position were associated. In aqueous NaOH solutions (4.4–17.5%, w/w), compound 14 showed a large increase in the ratio I E/I M (0.84–8.14) with the increase in NaOH concentration, compared to compound 13 (0.06–0.41). It was found that the association of hydrophobic groups at the reducing-end of cellulose could be controlled by the hydrophilic–hydrophobic balance of compounds and the solvent polarity.

ACS Sustainable Chemistry & Engineering, May 2, 2017

Holzforschung, Mar 13, 2013

ACS Sustainable Chemistry & Engineering, Dec 5, 2022

International Journal of Biological Macromolecules, Apr 1, 2019

Macromolecular Bioscience, Mar 9, 2010

Regioselectively ethylated celluloses, 2‐O‐ (1), 3‐O‐ (2), and 6‐O‐ethyl‐ (3) celluloses were syn... more Regioselectively ethylated celluloses, 2‐O‐ (1), 3‐O‐ (2), and 6‐O‐ethyl‐ (3) celluloses were synthesized via ring‐opening polymerization of glucopyranose orthopivalate derivatives. The number‐average degrees of polymerization (DPns) of compounds 1 and 2 were calculated to be 10.6 and 49.4, respectively. Three kinds of compound 3 with different DPns were prepared: DPns = 12.9 (3‐1), 60.3 (3‐2), and 36.1 (3‐3). The 2‐O‐, 3‐O‐, and 6‐O‐ethylcelluloses were soluble in water, confirmed by NMR analysis. Furthermore, the 3‐O‐ (2), and 6‐O‐ethyl‐ (3‐2) celluloses showed thermo‐responsive aggregation behavior and had a lower critical solution temperature (LCST) at about 40 °C and 70 °C, respectively, based on the results from turbidity tests and DSC measurements. The 6‐O‐ethyl‐cellulose (3‐3) with DPn = 36.1 and DPw = 54.6 showed gelation behavior over approx 70 °C, whereas the 6‐O‐ethyl‐celluloses 3‐1 and 3‐2 with lower and higher molecular weight, such as DPns 12.9 and 60.3, did not show gelation behavior at this temperature. It was revealed that the position of ethyl group affected the phase transition temperature. According to our experiments, the 3‐O‐ethyl and 6‐O‐ethyl groups along the cellulose chains caused the thermo‐responsive property of their aqueous solutions. The appropriate DP of the regioselective 6‐O‐ethyl‐cellulose existed for gelation of the aqueous solution.magnified image

ACS Sustainable Chemistry & Engineering

The Plant Journal, 2020

SUMMARYThe existence and formation of covalent lignin–carbohydrate (LC) linkages in plant cell wa... more SUMMARYThe existence and formation of covalent lignin–carbohydrate (LC) linkages in plant cell walls has long been a matter of debate in terms of their roles in cell wall development and biomass use. Of the various putative LC linkages proposed to date, evidence of the native existence and formation mechanism of phenyl glycoside (PG)‐type LC linkages in planta is particularly scarce. The present study aimed to explore previously overlooked mechanisms for the formation of PG‐type LC linkages through the incorporation of monolignol glucosides, which are possible lignin precursors, into lignin polymers during lignification. Peroxidase‐catalyzed lignin polymerization of coniferyl alcohol in the presence of coniferin and syringin in vitro resulted in the generation of PG‐type LC linkages in synthetic lignin polymers, possibly via nucleophilic addition onto quinone methide (QM) intermediates formed during polymerization. Biomimetic lignin polymerization of coniferin via the β‐glucosidase/...

Journal of Wood Science, 2020

In the original publication of the article, the letter “l” in the section headings was published ... more In the original publication of the article, the letter “l” in the section headings was published incorrectly as “l”. It should appear as “l” throughout the article.

ACS Sustainable Chemistry & Engineering, 2019

A biomimetic approach to the surface modification of nanocellulose is proposed. This strategy was... more A biomimetic approach to the surface modification of nanocellulose is proposed. This strategy was inspired by plant cell wall lignification, in which lignin, a hydrophobic biopolymer, tightly assem...

Journal of Wood Science, 2019

l-Coniferin (1L), which is an enantiomer of natural coniferin (d-coniferin (1D)), was prepared fr... more l-Coniferin (1L), which is an enantiomer of natural coniferin (d-coniferin (1D)), was prepared from l-glucose according to the conventional method for compound 1D. The reactivity of l-glucose and its derivatives was found to be almost same as that of the corresponding d-glucose and its derivatives during the preparation for compound 1L. Compound 1L showed resistance toward enzymatic hydrolysis by commercial β-glucosidase from Almond. However, unlike compound 1D, compound 1L was not transported across the membrane obtained from differentiating xylem of a hybrid poplar in the present assay. The result suggested for the first time that the d-/l-configuration of the glucose moiety of coniferin is an important factor affecting coniferin transport across the membrane.

Journal of Wood Science, 2016

Phytochemical Analysis, 2018

Macromolecules, Apr 10, 2020

Nucleation and Atmospheric Aerosols, 2022

Holzforschung, Feb 1, 2010

Journal of Wood Chemistry and Technology, Sep 1, 2006

Journal of Wood Chemistry and Technology, Apr 1, 2008

Cellulose, Oct 14, 2005

Novel cellobiose and cellulose (DP n =ca. 30) derivatives, N-(1-pyrenebutyloyl)-4-O-(β-d-glucopyr... more Novel cellobiose and cellulose (DP n =ca. 30) derivatives, N-(1-pyrenebutyloyl)-4-O-(β-d-glucopyranosyl)-β-d-glucopyranosylamine (6), N-(15-(1-pyrenebutyloylamino)-pentadecanoyl)-4-O-(β-d-glucopyranosyl)-β-d-glucopyranosylamine (7), N-(1-pyrenebutyloyl)-β-cellulosylamine (13), N-(15-(1-pyrenebutyloylamino)-pentadecanoyl)-β-cellulosylamine (14) carrying a pyrene group as a single fluorescent probe at the reducing end, were prepared in order to investigate their self-assembly systems in solutions. The relative intensity of the excimer emission at ca. 480 nm due to dimerized pyrenes (intensity I E) to the monomer emission at ca. 380 nm due to isolated pyrene (intensity I M), i.e., I E/I M, was monitored in various solutions. In water/dimethyl sulfoxide (DMSO) mixed solvent (0–98%, v/v), the ratio I E/I M remained low (0.04) for compound 6 over the range of water concentrations, indicating that pyrenes at C-1 position of compound 6 were diffused. On the other hand, the ratio I E/I M increased (0.04–4.96) for compound 7 with the increase in water concentration, indicating that pyrenes at C-1 position were associated. In aqueous NaOH solutions (4.4–17.5%, w/w), compound 14 showed a large increase in the ratio I E/I M (0.84–8.14) with the increase in NaOH concentration, compared to compound 13 (0.06–0.41). It was found that the association of hydrophobic groups at the reducing-end of cellulose could be controlled by the hydrophilic–hydrophobic balance of compounds and the solvent polarity.

ACS Sustainable Chemistry & Engineering, May 2, 2017

Holzforschung, Mar 13, 2013

ACS Sustainable Chemistry & Engineering, Dec 5, 2022

International Journal of Biological Macromolecules, Apr 1, 2019

Macromolecular Bioscience, Mar 9, 2010

Regioselectively ethylated celluloses, 2‐O‐ (1), 3‐O‐ (2), and 6‐O‐ethyl‐ (3) celluloses were syn... more Regioselectively ethylated celluloses, 2‐O‐ (1), 3‐O‐ (2), and 6‐O‐ethyl‐ (3) celluloses were synthesized via ring‐opening polymerization of glucopyranose orthopivalate derivatives. The number‐average degrees of polymerization (DPns) of compounds 1 and 2 were calculated to be 10.6 and 49.4, respectively. Three kinds of compound 3 with different DPns were prepared: DPns = 12.9 (3‐1), 60.3 (3‐2), and 36.1 (3‐3). The 2‐O‐, 3‐O‐, and 6‐O‐ethylcelluloses were soluble in water, confirmed by NMR analysis. Furthermore, the 3‐O‐ (2), and 6‐O‐ethyl‐ (3‐2) celluloses showed thermo‐responsive aggregation behavior and had a lower critical solution temperature (LCST) at about 40 °C and 70 °C, respectively, based on the results from turbidity tests and DSC measurements. The 6‐O‐ethyl‐cellulose (3‐3) with DPn = 36.1 and DPw = 54.6 showed gelation behavior over approx 70 °C, whereas the 6‐O‐ethyl‐celluloses 3‐1 and 3‐2 with lower and higher molecular weight, such as DPns 12.9 and 60.3, did not show gelation behavior at this temperature. It was revealed that the position of ethyl group affected the phase transition temperature. According to our experiments, the 3‐O‐ethyl and 6‐O‐ethyl groups along the cellulose chains caused the thermo‐responsive property of their aqueous solutions. The appropriate DP of the regioselective 6‐O‐ethyl‐cellulose existed for gelation of the aqueous solution.magnified image

ACS Sustainable Chemistry & Engineering

The Plant Journal, 2020

SUMMARYThe existence and formation of covalent lignin–carbohydrate (LC) linkages in plant cell wa... more SUMMARYThe existence and formation of covalent lignin–carbohydrate (LC) linkages in plant cell walls has long been a matter of debate in terms of their roles in cell wall development and biomass use. Of the various putative LC linkages proposed to date, evidence of the native existence and formation mechanism of phenyl glycoside (PG)‐type LC linkages in planta is particularly scarce. The present study aimed to explore previously overlooked mechanisms for the formation of PG‐type LC linkages through the incorporation of monolignol glucosides, which are possible lignin precursors, into lignin polymers during lignification. Peroxidase‐catalyzed lignin polymerization of coniferyl alcohol in the presence of coniferin and syringin in vitro resulted in the generation of PG‐type LC linkages in synthetic lignin polymers, possibly via nucleophilic addition onto quinone methide (QM) intermediates formed during polymerization. Biomimetic lignin polymerization of coniferin via the β‐glucosidase/...

Journal of Wood Science, 2020

In the original publication of the article, the letter “l” in the section headings was published ... more In the original publication of the article, the letter “l” in the section headings was published incorrectly as “l”. It should appear as “l” throughout the article.

ACS Sustainable Chemistry & Engineering, 2019

A biomimetic approach to the surface modification of nanocellulose is proposed. This strategy was... more A biomimetic approach to the surface modification of nanocellulose is proposed. This strategy was inspired by plant cell wall lignification, in which lignin, a hydrophobic biopolymer, tightly assem...

Journal of Wood Science, 2019

l-Coniferin (1L), which is an enantiomer of natural coniferin (d-coniferin (1D)), was prepared fr... more l-Coniferin (1L), which is an enantiomer of natural coniferin (d-coniferin (1D)), was prepared from l-glucose according to the conventional method for compound 1D. The reactivity of l-glucose and its derivatives was found to be almost same as that of the corresponding d-glucose and its derivatives during the preparation for compound 1L. Compound 1L showed resistance toward enzymatic hydrolysis by commercial β-glucosidase from Almond. However, unlike compound 1D, compound 1L was not transported across the membrane obtained from differentiating xylem of a hybrid poplar in the present assay. The result suggested for the first time that the d-/l-configuration of the glucose moiety of coniferin is an important factor affecting coniferin transport across the membrane.

Journal of Wood Science, 2016

Phytochemical Analysis, 2018