Biomedical subjects
Publications and source records attributed to Tsukasa Hatano.
A triphenylphosphine oxide (TPPO) compound bearing 3,4,5-tridodecyloxybenzyloxy moieties exhibits a columnar liquid crystalline phase, and by changing its self-assembled structure, is responsive to alkaline metal cations due to cation-phosphine oxide interactions.
The morphology of conjugate polymers (such as poly(ethylenedioxythiophene), poly(pyrrole), and poly(aniline)) can be controlled in their polymerization processes, by applying the concept of the templating method to oxidative polymerization. As oxidative polymerization of these monomers produces cationic intermediates, the anionic assemblies can act as potential templates due to the mutual electrostatic attractive force. Oxidative polymerization of ethylenedioxythiophene (EDOT), pyrrole, and aniline was carried out using helical superstructures of synthetic lipid assemblies as templates. Interestingly, we have found that oxidative polymerization of these monomers results in novel polymeric aggregates, such as a helical-tape structure and an intertwined helical structure, and that both the right-handed and left-handed helical structures can be created by a change in the hydrophilic head groups. This is the first example of helical superstructures composed of conjugate polymers that have been designed utilizing a convenient templating method.
The use of organogelators to template chiral and achiral polyaniline superstructures via the electrostatic interaction between anionic sulfonated polyaniline and a cationic gelator is described.
It was found that single-walled carbon nanotubes (SWNTs) solubilized into water by complexation with DNA (salmon testes) can be readily deposited on the ITO electrode by electrochemical oxidative polymerization of ethylenedioxythiophene (EDOT). The driving force for this novel deposition is an electrostatic interaction between the anionic charges of wrapping DNA and the cationic charges of poly(EDOT) formed in the oxidative polymerization process. The presence of poly(EDOT), SWNTs and DNA in the composite was confirmed by measurements of UV-Vis, IR, resonance Raman spectra, cyclic voltammetry (CV) and confocal laser scanning microscopy (CLSM). The composite adsorbed a DNA intercalator (ethidium bromide: EB) very efficiently, which is regarded to be further evidence for inclusion of DNA. The surface morphology, characterized by CLSM, SEM and AFM, featured the network structure consisting of 0.5-ca. 10 microm nanorods. Very interestingly, we found that photoexcitation of EB bound to the DNA generates the photocurrent, indicating that the excited energy of EB is injected into SWNTs, which is collected by the electroconductive poly(EDOT) film on the ITO electrode. We believe, therefore, that the present system is a very convenient method to explore new materials related to redox and photochemical functions.
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It was found that [60]fullerene encapsulated in p-sulfonatocalix[8]arene and single-walled carbon nanotubes (SWNTs) solubilized by sodium dodecylsulfate can be readily deposited on the ITO electrode by electrochemical oxidative polymerization of ethylenedioxythiophene (EDOT) without chemical modification of these carbon clusters. The driving force for the deposition is an electrostatic interaction between the anionic complexes and the cationic charges of poly(EDOT) formed in the oxidative polymerization process. The surface morphology was thoroughly characterized by scanning electron micrograph: the [60]fullerene/poly(EDOT) film is covered by nano-particles with 20-100 nm diameters whereas the SWNTs/poly(EDOT) film is covered by nanorods with several microm length and ca. 100 nm diameter. The results indicate that the anionic complexes act as nuclei for the polymer growth in the oxidation polymerization. Interestingly, when these modified ITO electrodes were photoirradiated, the appearance of a photocurrent wave was observed. The action spectra showed that the photoexcited energy of [60]fullerene or SWNTs is efficiently collected by the electroconductive poly(EDOT) film and transferred to the ITO electrode.
It was found that a one-dimensional rodlike structure of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) in water acts as a powerful template for electrochemical polymerization of ethylenedioxathiophene (EDOT) and pyrrole on an ITO electrode. Examination using CV and UV-vis spectroscopic examinations established that J-aggregated TPPS molecules are entrapped in the resultant poly(EDOT) and poly(pyrrole) films. SEM observation established that these monomers are electrochemically oxidized to grow up to a nanosized rodlike structure, reflecting the aggregation structure of TPPS. [structure: see text]
It was found that [60]fullerene encapsulated in anionic calix[8]arenes can be readily deposited by electrochemical oxidative polymerization of ethylenedioxythiophene: the resultant electrode generates a photocurrent wave (ca. 100 nA cm(-2)) in response to visible light irradiation.
The controlled colour generation and colour erasing phenomena of alkylammonium polyoxomolybdate complexes were first observed in the trans-(1R,2R)-1,2-bis(undecylcarbonylamino)cyclohexane organogel system using the sol-gel phase transition.