Mutsuo Tanaka

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Organization: National Institute of Advanced Industrial Science and Technology (AIST)

Department: Department of Information Science and Biomedical Engineering, Graduate School of Science and Engineering

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Chemicals
References

Frequency Dependence of Dynamic Properties of Polyethylene Glycol Molecules on Oscillating Solid–Liquid Interface

Co-reporter:Minoru Yoshimoto, Mutsuo Tanaka, and Shigeru Kurosawa

The Journal of Physical Chemistry C August 10, 2017 Volume 121(Issue 31) pp:16964-16964

Publication Date(Web):July 13, 2017

DOI:10.1021/acs.jpcc.7b03133

Frequency dependence of the resonant length of polyethylene glycol (PEG) on a solid–liquid interface oscillating at megahertz was studied by a quartz crystal microbalance (QCM). A QCM frequency and a number-average molecular weight (Mn) of PEG were changed systematically. This attempt revealed that, in all of the frequencies used, the series-resonant frequency shift, ΔF, of the QCM against the square root of the density-viscosity product of the PEG solutions was linear and had intercept. In addition, the systematical analysis made it clear that the ΔF slope was explainable by the Debye process, and the ΔF intercept became constant above the resonant length. These results led to the novel findings that the resonant length of the PEG molecules formed by physisorption was equal to that in the region of the viscous penetration depth and that the relationship between resonant length and QCM frequency was able to be explained by τ ∝ Mnν, where τ is a relaxation time of molecule and ν is a constant. In particular, we found that the resonant length of physisorption was smaller than that of chemisorption but that the frequency dependency was equal to each other.

Dynamic Properties of Self-Assembled Monolayers of Mercapto Oligo(ethylene oxide) Methyl Ether on an Oscillating Solid–Liquid Interface

Co-reporter:Minoru Yoshimoto ; Keita Honda ; Shigeru Kurosawa

The Journal of Physical Chemistry C 2014 Volume 118(Issue 29) pp:16067-16073

Publication Date(Web):July 1, 2014

DOI:10.1021/jp411186n

The dynamic properties of chemisorbed soft matter on a solid–liquid interface oscillating at megahertz were investigated using a quartz crystal microbalance (QCM). As a chemisorbed soft matter, we employed the self-assembled monolayers of mercapto oligo(ethylene oxide) methyl ethers, HS(CH2CH2O)nCH3 (n = 5, 11, 12, 19, 27, 35, and 43), where those molecular weights had unity. The systematic analyses on the basis of the Voight model revealed that the molecular thickness moving with the solid–liquid interface oscillating at megahertz frequencies, the resonant length, is 8.8 nm, where the frequency dependence of the resonant length is not considered. On the other hand, the analyses based on the Debye process revealed that the logarithm of the resonant length linearly decreases with the logarithm of 2πF, where F is the frequency of the QCM, and varies from 17.3 (9 MHz) to 12.4 nm (81 MHz). Those values in the Debye process were within twice that of the Voight model and were approximately consistent with that in the Voight model. On the basis of the experimental data, we proposed the equation with the resonant length of HS(CH2CH2O)nCH3 as a function of frequency. Moreover, we discussed the difference between the chemisorbed and the physisorbed molecules on the solid–liquid interface oscillating at megahertz frequencies.

Surface Modification of Silicon Oxide with Trialkoxysilanes toward Close-Packed Monolayer Formation

Co-reporter:Mutsuo Tanaka, Takahiro Sawaguchi, Masashi Kuwahara, and Osamu Niwa

Langmuir 2013 Volume 29(Issue 21) pp:6361-6368

Publication Date(Web):May 2, 2013

DOI:10.1021/la4009834

In order to scrutinize potential of trialkoxysilanes to form close-packed monolayer, surface modification of silicon oxide was carried out with the trialkoxysilanes bearing a ferrocene moiety for analysis by electrochemical methods. As it was found that hydrogen-terminated silicon reacts with trialkoxysilane through natural oxidation in organic solvents, where the silicon oxide layer is thin enough to afford conductivity for electrochemical analysis, hydrogen-terminated silicon wafer was immersed in trialkoxysilane solution for surface modification without oxidation treatment. Cyclic voltammetry measurements to determine surface concentrations of the immobilized ferrocene–silane on silicon surface were carried out with various temperature, concentration, solvent, and molecular structure, while the blocking effect in the cyclic voltammogram was investigated to obtain insight into density leading to the close-packed layer. The results suggested that a monolayer modification tended to occur under milder conditions when the ferrocene–silane had a longer alkyl chain, and formation of a close-packed layer to show significant blocking effect was observed. However, the surface modification proceeded even when surface concentration of the immobilized ferrocene–silane was greater than that expected for the monolayer. On the basis of these tendencies, the surface of silicon oxide modified with trialkoxysilane is considered to be a partial multilayer rather than monolayer although a close-packed layer is formed. This result is supported by the comparison with carbon surface modified with ferrocene–diazonium, in which a significant blocking effect was observed when surface concentrations of the immobilized ferrocene moiety are lower than that for silicon oxide modified with ferrocene–silane.

Design and Fabrication of Biosensing Interface for Waveguide-Mode Sensor

Co-reporter:Mutsuo Tanaka, Kyoko Yoshioka, Yoshiki Hirata, Makoto Fujimaki, Masashi Kuwahara, and Osamu Niwa

Langmuir 2013 Volume 29(Issue 42) pp:13111-13120

Publication Date(Web):2017-2-22

DOI:10.1021/la402802u

In order to develop a biosensing system with waveguide-mode sensor, fabrication of a biosensing interface on the silica surface of the sensing chip was carried out using triethoxysilane derivatives with anti-leptin antibody. Triethoxysilane derivatives bearing succinimide ester and oligoethylene glycol moieties were synthesized to immobilize the antibody and to suppress nonspecific adsorption of proteins, respectively. The chip modified with triethoxysilane derivatives bearing oligoethylene glycol moiety suppressed nonspecific adsorption of proteins derived from human serum effectively by rinse with PBS containing surfactant (0.05% Tween 20). On the other hand, it was confirmed that antibody was immobilized on the chip by immersion into antibody solution to show response of antigen–antibody reaction, where the chip was modified with triethoxysilane derivatives bearing succinimide ester moiety. When the interface was fabricated with antibody and a mixture of triethoxysilane derivatives bearing succinimide ester and oligoethylene glycol moieties, the response of antigen–antibody reaction depended on composition of the mixture and enhanced with the increase of ratio for triethoxysilane derivatives bearing succinimide ester moiety reflecting the antibody concentration immobilized on the chip. While introduction of excess triethoxysilane derivatives bearing succinimide ester moiety induced nonspecific adsorption of proteins derived from human serum, the immobilized antibody on the chip kept its activity after 1-month storage in a refrigerator. Taking into consideration those factors, the biosensing interface was fabricated using triethoxysilane derivatives with anti-leptin antibody to examine performance of the waveguide-mode sensor. It was found that the detection limits for human leptin were 50 ng/mL in PBS and 100 ng/mL in human serum. The results demonstrate that the waveguide-mode sensor powered by the biosensing interface fabricated with those triethoxysilane derivatives and antibody has potential to detect several tens of nanograms per milliliter of biomarkers in human serum with an unlabeled detection method.

Surface Modification of GC and HOPG with Diazonium, Amine, Azide, and Olefin Derivatives

Co-reporter:Mutsuo Tanaka, Takahiro Sawaguchi, Yukari Sato, Kyoko Yoshioka, and Osamu Niwa

Langmuir 2011 Volume 27(Issue 1) pp:170-178

Publication Date(Web):November 30, 2010

DOI:10.1021/la1035757

Surface modification of glassy carbon (GC) and highly oriented pyrolytic graphite (HOPG) was carried out with diazonium, amine, azide, and olefin derivatives bearing ferrocene as an electroactive moiety. Features of the modified surfaces were evaluated by surface concentrations of immobilized molecule, blocking effect of the modified surface against redox reaction, and surface observation using cyclic voltammetry and electrochemical scanning tunneling microscope (EC-STM). The measurement of surface concentrations of immobilized molecule revealed the following three aspects: (i) Diazonium and olefin derivatives could modify substrates with the dense-monolayer concentration. (ii) The surface concentration of immobilized amine derivative did not reach to the dense-monolayer concentration reflecting their low reactivity. (iii) The surface modification with the dense-monolayer concentration was also possible with azide derivative, but the modified surface contained some oligomers produced by the photoreaction of azides. Besides, the blocking effect against redox reaction was observed for GC modified with diazonium derivative and for HOPG modified with diazonium and azide derivatives, suggesting fabrication of a densely modified surface. Finally, the surface observation for HOPG modified with diazonium derivative by EC-STM showed a typical monolayer structure, in which the ferrocene moieties were packed densely at random. On the basis of those results, it was demonstrated that surface modification of carbon substrates with diazonium could afford a dense monolayer similar to the self-assembled monolayer (SAM) formation.

Synthesis of phosphorylcholine–oligoethylene glycol–alkane thiols and their suppressive effect on non-specific adsorption of proteins

Co-reporter:Mutsuo Tanaka, Takahiro Sawaguchi, Yukari Sato, Kyoko Yoshioka, Osamu Niwa

Tetrahedron Letters 2009 50(28) pp: 4092-4095

Publication Date(Web):

DOI:10.1016/j.tetlet.2009.04.091

Synthesis and Photochromism of Novel Chromene Derivatives Bearing a Monoazacrown Ether Moiety

Co-reporter:Saleh A. Ahmed;Hisanori Ando;Hitoshi Iwamoto;Keiichi Kimura

European Journal of Organic Chemistry 2003 Volume 2003(Issue 13) pp:

Publication Date(Web):16 JUN 2003

DOI:10.1002/ejoc.200300070

Crowned chromenes − four novel naphthopyrans (chromenes) bearing monoaza-12-crown-4, -15-crown-5, -18-crown-6, and a noncyclic analogue at the 5-position − were synthesized, and their photochromism in acetonitrile was examined in the presence of alkali and alkaline-earth metal ions. Incorporation of crown ether units to chromene moieties facilitated to a great extent both the thermal isomerization and photoisomerization of the chromene moiety, reflecting the metal-ion-binding ability of the crown ether moiety. Comparison of the crowned chromenes with the corresponding crowned spirobenzopyrans reveals that photochromism of the crowned chromene reflects an interaction between the metal ion and the crown ether moiety that is stronger than that of the crowned spirobenzopyran, and shows only positive photochromism with significant red-shifts in the UV/Vis absorption spectra, in contrast to the crowned spirobenzopyrans reported previously. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Decisive Factors in the Photoisomerization Behavior of Crowned Spirobenzopyrans: Metal Ion Interaction with Crown Ether and Phenolate Anion Moieties

Co-reporter:Abdussalam M. A. Salhin;Kenji Kamada;Hisanori Ando;Tomokazu Ikeda;Yasuhiko Shibutani;Setsuko Yajima;Makoto Nakamura;Keiichi Kimura

European Journal of Organic Chemistry 2002 Volume 2002(Issue 4) pp:

Publication Date(Web):18 JAN 2002

DOI:10.1002/1099-0690(200202)2002:4<655::AID-EJOC655>3.0.CO;2-6

The influence of metal ion interaction with crowned spirobenzopyrans on the photoisomerization behavior was investigated through the use of various solvents, crowned spirobenzopyrans, and metal ions. Studies on the photoisomerization behavior of crowned spirobenzopyrans in various solvents revealed that solvation of the phenolate anion moiety in the merocyanine form induced photoisomerization back to the spiropyran form, giving rise to negative photochromism. Metal ion interaction with the phenolate anion moiety similarly caused photoisomerization back to the spiropyran form, while that with the crown ether moiety just produced a polar environment and its influence on photoisomerization behavior was dependent on the affinity of the metal ion captured by the crown ether moiety for the phenolate anion. Therefore, photochromic switching of crowned spirobenzopyrans between positive and negative to control the metal ion interaction with the phenolate anion moiety through the crown ether moiety is possible. This finding suggests a molecular design method for crowned spirobenzopyrans showing desired ion-responsive photochromism.

Rheology of self-assembled monolayers on solid-liquid interface oscillating at MHz frequency

Co-reporter:Minoru Yoshimoto, Keita Honda, Shigeru Kurosawa, Mutsuo Tanaka

Chinese Journal of Physics (February 2017) Volume 55(Issue 1) pp:16-21

Publication Date(Web):1 February 2017

DOI:10.1016/j.cjph.2016.11.009

•The rheology of chemisorbed soft matters oscillating at MHz was studied using a QCM.•The SAMs of HS(CH2CH2O)nCH3 were employed as a soft matter.•The systematical analyses revealed the relationships of η∞Mn0.180 and μ∞Mn0.344 (Mn: molecular weight).The rheology properties (viscosity and elasticity) of chemisorbed soft matters on a solid-liquid interface oscillating at MHz were investigated using a quartz crystal microbalance (QCM). As a chemisorbed soft matter, we employed the self-assembled monolayers (SAMs) of mercapto oligo(ethylene oxide) methyl ethers, HS(CH2CH2O)nCH3 (n = 5, 11, 12, 19, 27, 35 and 43), where those molecular weights had unity. The systematical analyses on the basis of the Voight model revealed the relationships of η∝Mn0.180 and μ∝Mn0.344, where η and μ are the viscosity and elasticity of the SAM, and Mn is the molecular weight of HS(CH2CH2O)nCH3. As a result, we found that the SAM consisting of the oligomer followed the formula of polymer.

Properties of modified surface for biosensing interface

Co-reporter:Mutsuo Tanaka, Takahiro Sawaguchi, Yoshiki Hirata, Osamu Niwa, Keiko Tawa, Chisato Sasakawa, Koji Kuraoka

Journal of Colloid and Interface Science (1 July 2017) Volume 497() pp:

Publication Date(Web):1 July 2017

DOI:10.1016/j.jcis.2017.02.070

Properties of modified surface, behavior against salting-out effect, suppressive effect for protein nonspecific adsorption, and wettability were examined using various mercapto compounds bearing methyloligoethylene glycol, oligoethylene glycol, alkyl oligoethylene glycol, alkyl phosphoryl choline, alkyl inverse phosphoryl choline, and alkyl sulfobetaine moieties. The behavior against salting-out effect was examined using gold nanoparticle with PBS and NaCl aqueous solution. The suppressive effect for protein nonspecific adsorption was evaluated by SPR, and the wettability was measured on the SPR chip. The gold nanoparticle modified with 8C3EG, 12C4EG, 12CPC, 6CCP, and 12CCP showed excellent behavior against salting-out effect. The suppression of protein nonspecific adsorption was effective with 6EG, 12C4EG, 12CPC, and 12CS. On the other hand, the modified surface possessed high wettability except for the surface modified with M6EG. The results indicate that incorporation of alkyl group into surface modification materials is effective for the enhancement of behavior against salting-out effect and suppressive effect for protein nonspecific adsorption regardless of wettability. Among the zwitter ionic derivatives, inverse phosphoryl choline derivatives showed intriguing properties, high behavior against salting-out effect with high wettability but low suppressive effect for protein nonspecific adsorption.In this work, properties of modified surface with various mercapto compounds were evaluated in point of protein adsorption, salting-out effect, wettability, and hydration layer.