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ABSTRACT: To extend the concept of the Cerasome, an organic-inorganic vesicular nanohybrid, this paper investigates the preparation
and characterization of a “mixed” Cerasome. The system consists of a Cerasome-forming lipid 1, a cationic synthetic lipid 2, and a zwitterionic phospholipid 3. Lipid mixtures of 1 and 2 or 1 and 3 were used to prepare the mixed Cerasomes. Their lipid distributions were examined using differential scanning calorimetry
(DSC), which showed that 1 and 2 (or 1 and 3) were phase-separated in the mixed Cerasomes. These results seem to be mainly attributable to the polymerizable nature of
1. Results of scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX) showed that 1 and 3 were both incorporated into a single Cerasome, not macroscopically separated to form separate vesicles from each lipid component.
Mixed Cerasomes of 1 and 2 showed high morphological stability against a membrane-solubilizing surfactant, incorporating up to 70% of 2. On the other hand, the mixed Cerasomes from 1 and 3 were less stable than the mixed Cerasomes from 1 and 2. This relative instability might be attributable to differences between the mixed Cerasomes from 1 and 2 and 1 and 3 in terms of their vesicular sizes, lipid domain sizes, and their relative effectiveness for siloxane network formation. These
results strongly support the formation of mixed Cerasomes that have lipid domains in-plane. Systems described in this study
are useful to prepare variously mixed Cerasomes that have different surface functionalities and in-plane lipid distribution,
but which have high morphological stability.
Journal of Sol-Gel Science and Technology 04/2012; 40(2):227-232. · 1.63 Impact Factor
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ABSTRACT: Lipid-membrane-incorporating C(60) and C(70) (LMIC(60) and LMIC(70)) were prepared by the fullerene-exchange reaction from the γ-cyclodextrin cavity to vesicles (we call this method the "exchange method"). An advantage of this method is that the ratios of [C(60)]/[lipids] and [C(70)]/[lipids] can be arbitrarily controlled by adjusting the ratios of the fullerenes and liposome. The maximum ratio (30 mol%) obtained was approximately 14 and 100 times higher than those achieved for LMIC(60) and LMIC(70) , respectively, that were prepared by the classical method, which we call the "premixing method" (dissolving lipids and C(60) or C(70) in chloroform, followed by concentration and extraction with water). Furthermore, the stabilities and photodynamic activities of the LMIC(60) and LMIC(70) solutions prepared by the exchange method were shown to be much higher than those prepared by the premixing method. That is, the exchange method was found to be superior to the premixing method as a preparative method of LMIC(60) and LMIC(70) for applications in photomedical and photomaterials chemistry.
Chemistry - An Asian Journal 03/2012; 7(3):605-13. · 4.50 Impact Factor
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ABSTRACT: This study demonstrated that gel-like polyion complexes obtained by mixing of aqueous solution of chondroitin sulfate, heparin, and hyaluronic acid with that of chitosan were able to form their free-standing films using hot press treatments. These films, having thicknesses ca. 50 and 100 μm, depending on the spacer thickness, were homogeneous and non-porous at the microscopic level, and were not water-soluble. The present fabrication process required neither cross-coupling agents nor introduction of other functional groups to the polysaccharides. Hydroxyapatite deposition on the film surfaces under body fluid conditions was also achieved.
Colloids and surfaces. B, Biointerfaces 07/2011; 88(1):534-8. · 2.60 Impact Factor
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ABSTRACT: Preparation of colloidal hydroxyapatite (HAp) particles under body fluid conditions was investigated with focusing on the effect of preparative conditions on crystallinity of the resulting particles. Tris(hydroxymethyl)aminomethane was added to 1.5SBF (a solution having 1.5 times higher ion concentrations than those of a simulated body fluid, SBF) to increase the solution pH, which resulted in induction of homogeneous nucleation of HAp in the solution. Colloidal HAp particles having diameters about 300 nm were obtained. When the reaction was proceeded at 70°C and the sample was dried by heating, it was effective to obtain HAp particles having high crystallinity. Experimental results support that remaining water in the sample contributed to increase HAp crystallinity.
Colloids and surfaces. B, Biointerfaces 02/2011; 84(2):545-9. · 2.60 Impact Factor
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ABSTRACT: Biomimetic mineralization of supramolecular scaffolds consisting of biomolecules or their analogues has received much attention recently from the viewpoint of creation of novel biomaterials. This study investigated biomimetic deposition of hydroxyapatite (HAp) on cerasomes, morphologically stable organic-inorganic hybrid vesicles. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction studies revealed that the pristine cerasomes induced heterogeneous nucleation of HAp when they were immersed in 1.5SBF, a solution having 1.5 times higher ion concentration than that of a simulated body fluid (SBF). The HAp deposition was further accelerated when dicarboxylic and monocarboxylic acid groups were displayed on cerasome surfaces. These carboxylic acid groups are expected to enhance calcium ion binding to the cerasome surface, causing an increase of HAp nucleation sites. At lower surface concentrations on the cerasome surface, the dicarboxylic acid group is apparently more effective for HAp deposition than the monocarboxylic acid group. The resultant HAp-cerasome hybrids are useful as biocompatible materials having unique properties deriving from the lipid bilayer structure of the cerasomes.
Journal of Materials Science Materials in Medicine 08/2009; 21(1):11-9. · 2.32 Impact Factor
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Atsushi Ikeda,
Mai Nagano,
Motofusa Akiyama,
Masashi Matsumoto,
Sayuri Ito,
Masaru Mukai, Mineo Hashizume,
Jun-ichi Kikuchi,
Kiyofumi Katagiri,
Takuya Ogawa,
Tatsuo Takeya
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ABSTRACT: [70]Fullerene (C(70)) encapsulated into a surface-cross-linked liposome, a so-called cerasome, was prepared by an exchange reaction incorporating C(70)gamma-cyclodextrin complexes into lipid membranes. Fullerene exchange in a cerasome-incorporated C(70) (CIC(70)), as well as in a lipid-membrane-incorporated C(70) (LMIC(70)), was completed within 1 min with stirring at 25 degrees C. CIC(70) was more resistant to lysis than LMIC(70) towards lysing agents such as surfactants. Furthermore, the photodynamic activity of CIC(70) in HeLa cells was similar to that of LMIC(70), indicating that C(70) can act as a photosensitizing drug (PS) without release from cerasome membranes. Thus, in contrast with general drug-delivery systems (DDSs), which require the drug to be released from the interior of liposomes, carriers for PSs for use in photodynamic therapy (PDT) do not necessarily need to release the drug. These results indicate that DDSs with high morphological stability can increase the residence time in blood and achieves tumor-selective drug delivery by the enhanced permeability and retention (EPR) effect.
Chemistry - An Asian Journal 11/2008; 4(1):199-205. · 4.50 Impact Factor
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ABSTRACT: We solubilised SWNTs of short length using a mechanochemical high-speed vibration milling (HSVM) through formation of complexes between the SWNTs and chelate complexes; the mixture formed a network structure on mica.
Chemical Communications 05/2008; · 6.17 Impact Factor
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Journal of the American Chemical Society 05/2007; 129(14):4140-1. · 9.91 Impact Factor
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ABSTRACT: Intracellular uptake of a lipid-membrane-incorporated C(60) with a cationic surface into HeLa cells was found to induce cell death under visible light irradiation in high efficiency.
Organic & Biomolecular Chemistry 05/2007; 5(8):1158-60. · 3.70 Impact Factor
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ABSTRACT: A novel class of organic-inorganic hybrids, the so-called cerasomes, which have a bilayer vesicular structure and a silicate surface, has been synthesized by combination of sol-gel reaction and self-assembly of organoalkoxysilanes with a molecular structure analogous to lipids. We have synthesized two cerasome-forming organoalkoxysilanes, N-[N-(3-triethoxysilyl)propylsuccinamoyl]dihexadecylamine (1) and N,N-dihexadecyl-N (alpha)-[6-[(3-triethoxysilyl)propyldimethylammonio]hexanoyl]glycinamide bromide (2), and investigated the synthetic conditions of the cerasomes and their structural characteristics. For the proamphiphilic 1, the cerasome was obtained under restricted pH conditions where acid-catalyzed hydrolysis of the triethoxysilyl moiety proceeded without disturbing the vesicle formation. In contrast, the amphiphilic 2, additionally having a hydrophilic quaternary ammonium group, formed stable dispersions of the cerasome in a wide pH range. The hydrolysis behavior of the triethoxysilyl groups was monitored by (1)H NMR spectroscopy. Morphology of the cerasomes having the liposomal vesicular structure was confirmed by TEM observations. Extent of the development of siloxane networks through condensation among the silanol groups on the cerasome surface was evaluated by using MALDI-TOF-MS spectrometry. Formation of oligomers of the cerasome-forming lipids in the vesicle was clearly confirmed. Due to the siloxane network formation, the cerasome showed remarkably high morphological stability compared with a reference liposome, as evaluated by surfactant dissolution measurements.
Chemistry 02/2007; 13(18):5272-81. · 5.93 Impact Factor
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ABSTRACT: A new molecular design of fullerene derivatives exhibiting trigger-responsive self-aggregation in organic solvents has been established. Calix[4]arene was covalently connected with fullerene in order to apply host-guest interaction to the aggregation control. The self-assembly behaviour was studied in organic solvents by UV-vis absorption spectroscopy, dynamic light scattering and transmission electron microscopy. Results show that the bisfullerene formed self-aggregations with a low polydispersity index due to the fullerenes' tendency to aggregate in polar organic solvents. Furthermore, the aggregate sizes can be changed readily by solvent composition and the addition of guest cations. Especially, disaggregation of the bisfullerene was induced by addition of LiClO4 or NaClO4.
Organic & Biomolecular Chemistry 03/2006; 4(3):519-23. · 3.70 Impact Factor
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ABSTRACT: Novel organic-inorganic nanohybrids, each having an inorganic core covered with an asymmetric lipid-bilayer membrane, were prepared through two-step self-assembling of a Cerasome-forming organoalkoxysilane lipid, N-[N-(3-triethoxysilyl)propylsuccinamoyl]dihexadecylamine (1), as the inner layer with an appropriate bilayer-forming amphiphile, N,N-dihexadecyl-N alpha-[6-(trimethylammonio)hexanoyl]alaninamide bromide (2), sodium N,N-dihexadecyl-N alpha-(6-sulfohexanoyl)alaninamide (3), or dimyristoylphosphatidylcholine (DMPC; 4), as the outer layer on a monodispersed colloidal silica particle. The particle thus obtained was characterized by various physical measurements, such as FT-IR spectroscopy, transmission electron microscopy, differential scanning calorimetry, and zeta-potential measurements. These data strongly supported the successful formation of the asymmetric bilayer structure on the surface of the silica particle. The current method is widely applicable to various kinds of hybrids of inorganic particles with lipid membrane components.
Colloids and Surfaces B Biointerfaces 12/2004; 38(3-4):149-53. · 3.46 Impact Factor
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ABSTRACT: Morphological characterization of the organic-inorganic vesicular nanohybrids, Cerasomes, was performed in aqueous media from two aspects. Firstly, a novel Cerasome-forming lipid having two triethoxysilyl groups in the head moiety was synthesized and the physical property of the Cerasome was investigated. While the morphological stability of the Cerasomes, as evaluated from the vesicular collapse behavior against a micelle-forming nonionic surfactant, Triton-X 100, was extremely higher than that of the conventional phospholipid liposome, the stabilities were comparable to each other for the Cerasomes derived from the dual- and single-head lipids. On the other hand, the surface property of the Cerasome formed with the dual-head lipid more closely resembled the colloidal silica particles rather than that derived from the single-head lipid, as suggested by zeta-potential measurements. Secondly, the effect of the media pH on the morphological stability of the Cerasome formed with the single-head lipid was evaluated and appeared as a time difference in obtaining the morphological stability of the Cerasome. These morphological characteristics of the Cerasomes could be mainly owing to the development of the siloxane network on the vesicular surface.
Journal of Sol-Gel Science and Technology 07/2004; 31(1):99-102. · 1.63 Impact Factor
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ABSTRACT: Employing a layer-by-layer assembly technique, we created three-dimensional architectures of silica and silica-like particles on solid interfaces. Atomic force and scanning electron microscopy confirmed a size-selection effect for assembling a mixture of two kinds of monodispersed silica particles prepared through the sol-gel process. Size-selective assembly was also applied for layer-by-layer organization of Cerasomes, which are organic-inorganic vesicular hybrids with a silica-like structure on the lipid bilayer surface. This study obtained an alternating layer-by-layer assembly of Cerasomes with a relatively uniform size on solid interfaces from polydispersed aqueous colloids of a surface-modified cationic Cerasome with an unmodified anionic Cerasome or an anionic poly(vinyl sulfate). Quartz crystal microbalance measurements and atomic force microscopy were used to evaluate this assembly process.
Journal of Sol-Gel Science and Technology 07/2004; 31(1):59-62. · 1.63 Impact Factor
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ABSTRACT: Cerasomes, liposomal membranes covered with ceramic surface, were prepared from double-chain organoalkoxysilane lipids with a hydrogen-bonding unit by using ethanol sol injection method. The Cerasomes thus prepared were characterized by means of various physical measurements such as scanning and transmission electron microscopy, light scattering and differential scanning calorimetry. As compared with liposomes formed with a lipid having a quaternary ammonium head in place of the inorganic moiety, the Cerasomes were more stable to maintain their vesicular structures even in the presence of excessive amounts of a surfactant, in which the conventional liposomes were completely dissolved. Potential of the Cerasome as an organic–inorganic hybrid material for nano-device fabrications were discussed.
Thin Solid Films · 1.89 Impact Factor
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ABSTRACT: Two kinds of functionalization of a lipid bilayer vesicle by titania were achieved by utilizing a cerasome-forming lipid, which is the starting material to prepare a cerasome, a morphologically stable lipid bilayer vesicle having an atomic layer of siloxane networks on its surface. One system is the preparation of the titania-coated cerasomes by immobilizing nanaometer-sizes of titania onto the surface siloxane network of cerasomes. The other is the creation of an asymmetric lipid bilayer structure on the surface of the colloidal titania particles. The characteristics of these surface- and core-functionalized vesicles were investigated, and it was found that these conjugates showed photocatalytic activity as evaluated by photolysis experiments of the cationic dye methylene blue.
Bioconjugate Chemistry 17(4):1099-104. · 4.93 Impact Factor
