JP2010260882A - Method for dispersing lipid nanotube in organic solvent, and lipid nanotube liquid crystal composed of the dispersion - Google Patents

Method for dispersing lipid nanotube in organic solvent, and lipid nanotube liquid crystal composed of the dispersion Download PDF

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JP2010260882A
JP2010260882A JP2009110252A JP2009110252A JP2010260882A JP 2010260882 A JP2010260882 A JP 2010260882A JP 2009110252 A JP2009110252 A JP 2009110252A JP 2009110252 A JP2009110252 A JP 2009110252A JP 2010260882 A JP2010260882 A JP 2010260882A
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lipid
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nanotubes
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JP5366133B2 (en
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Hiroyuki Namikawa
博之 南川
Koji Abe
浩司 安部
Mitsutoshi Masuda
光俊 増田
Toshimi Shimizu
敏美 清水
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National Institute of Advanced Industrial Science and Technology AIST
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for dispersing lipid nanotubes, by which a good dispersion state for a long period of time can be maintained in an organic solvent without changing configurations of the lipid nanotubes obtained by self-assembly of an N-glycoside type glycolipid, and to provide a dispersion obtained by the method. <P>SOLUTION: The dispersion of lipid nanotubes, which is stable for a long period of time, can be obtained by a moderate, easy and short-time method without modification and changes in the configurations of the nanotubes while effectively suppressing attractive force or association among the lipid nanotubes, by matching the density and the refractive index of an organic solvent to be used as a dispersion medium to those of the lipid nanotubes to be dispersed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、有機溶媒中での脂質ナノチューブの分散方法、及びその分散液からなる脂質ナノチューブ液晶に関する。   The present invention relates to a method for dispersing lipid nanotubes in an organic solvent and a lipid nanotube liquid crystal comprising the dispersion.

水溶液中で自己集合して得られる有機ナノチューブは既に公知である。この有機ナノチューブは、中空シリンダー部の内孔サイズが5〜500nmであり、シクロデキストリンよりも一桁以上大きいため、シクロデキストリンでは包接することができない5〜500nmの径を有するタンパク質、ウイルス、薬剤、金属微粒子などの機能性物質をその中空シリンダー内部に捕捉できる可能性があり、その用途開発が期待されている。
本発明者等は、既に水溶液中で自己集合して得られる有機ナノチューブを開発している(特許文献1、非特許文献1)。
Organic nanotubes obtained by self-assembly in an aqueous solution are already known. This organic nanotube has a hollow cylinder portion with an inner pore size of 5 to 500 nm, which is one or more orders of magnitude larger than cyclodextrin, so that proteins, viruses, drugs having a diameter of 5 to 500 nm that cannot be included in cyclodextrin, There is a possibility that functional substances such as metal fine particles can be trapped inside the hollow cylinder, and development of their use is expected.
The present inventors have already developed an organic nanotube obtained by self-assembly in an aqueous solution (Patent Document 1, Non-Patent Document 1).

しかし、この有機ナノチューブは、水溶液中で合成されてきたため、その製造には水を大量に必要とする上に、加熱撹拌操作と長時間の放置を必要としていたため、量産化が困難であった。また、この有機ナノチューブは、水溶液中で合成されるため、その構造中に強固に水を保持しており、通常の方法ではその水を除くことが困難であり、この有機ナノチューブ内へ機能性物質の包接を効率良く行うことができないという問題があった。   However, since these organic nanotubes have been synthesized in an aqueous solution, their production requires a large amount of water, and also requires a heating and stirring operation and standing for a long time, so that mass production is difficult. . In addition, since this organic nanotube is synthesized in an aqueous solution, water is firmly held in its structure, and it is difficult to remove the water by a normal method. There was a problem that it was not possible to efficiently perform inclusion.

そこで、本発明者らは、従来の有機ナノチューブにおける上記問題を解決し、機能性物質を効率的に包接することのできる、水分を含まない有機ナノチューブの合成方法について検討した結果、N−グリコシド型糖脂質又はペプチド脂質を、水ではなく有機溶媒中で自己集合させることによって、水分を含まない有機ナノチューブを簡便かつ大量に製造できることを見出した(特許文献2)。   Accordingly, the present inventors have studied the method for synthesizing organic nanotubes that do not contain water and that can solve the above-mentioned problems in conventional organic nanotubes and can efficiently include functional substances. It has been found that organic nanotubes not containing water can be produced easily and in large quantities by self-assembling glycolipids or peptide lipids in an organic solvent instead of water (Patent Document 2).

特許第3664401号公報Japanese Patent No. 3664401 特開2008−30185号公報JP 2008-30185 A

S.Kamiya, H.Minamikawa, J.H.Jung, B.Yans, M.Masuda, T.Shimizu, Langmuir, 2005, 21, 743-750S. Kamiya, H. Minamikawa, J.H. Jung, B. Yans, M. Masuda, T. Shimizu, Langmuir, 2005, 21, 743-750

前述のN−グリコシド型糖脂質が自己集合した有機ナノチューブ(以下、「脂質ナノチューブ」ということもある。)の外表面は、相対的に疎水性な性質を持っていると考えられ、各種の機能性有機化合物との複合化が期待されるが、機能性有機化合物との複合化のためには、脂質ナノチューブを、その形態を保ったまま、良好に長期間分散させることが必要となる。   The outer surface of the organic nanotube (hereinafter also referred to as “lipid nanotube”) in which the aforementioned N-glycoside type glycolipid is self-assembled is considered to have a relatively hydrophobic property, and has various functions. Complexing with a functional organic compound is expected, but for complexing with a functional organic compound, it is necessary to disperse the lipid nanotubes well for a long period of time while maintaining the form.

しかしながら、従来の技術では、水中で有機ナノチューブを長期間分散・配向させるためには、表面に電荷を導入したうえ、強い解離を保つためにpH3以下の強酸性条件或いはpH9以上の強アルカリ条件が必要とされていた。
また、有機溶媒中で有機ナノチューブを分散させる場合、溶媒に完全に脂質分子が単分子状態で溶解してしまうか、或いは溶解しない場合でも、脂質チューブがランダム会合して数分程度の短時間のうちに凝集してしまい、脂質ナノチューブの形態を保ったまま長期間良好に分散させる方法はなかった。
However, in the prior art, in order to disperse and orient the organic nanotubes in water for a long period of time, in addition to introducing a charge on the surface, strong acidic conditions of pH 3 or lower or strong alkaline conditions of pH 9 or higher are required to maintain strong dissociation. Was needed.
In addition, when organic nanotubes are dispersed in an organic solvent, even if lipid molecules are completely dissolved in a single molecule state or not dissolved in the solvent, the lipid tubes are randomly associated to form a short time of about several minutes. There was no method of agglomerating and dispersing well for a long time while maintaining the shape of the lipid nanotube.

本発明は、こうした事情を鑑みてなされたものであって、有機溶媒中で、脂質ナノチューブの形態を変化することなく、長期間良好な分散状態を維持することが可能な、脂質ナノチューブの分散方法及びその分散液を提供することを目的とするものである。   The present invention has been made in view of such circumstances, and is a method for dispersing lipid nanotubes that can maintain a good dispersion state for a long period of time without changing the shape of the lipid nanotubes in an organic solvent. And a dispersion thereof.

本発明者らは、上記目的を達成すべく鋭意研究を重ねた結果、分散媒として、特定の密度と屈折率をもつ有機溶媒を選択することにより、脂質ナノチューブの形態を保持したまま、長期間良好な分散状態を保持しうる分散液を実現することができることが判明した。すなわち、分散媒として用いる有機溶媒の密度及び屈折率を、分散させる脂質ナノチューブとマッチングさせることにより、脂質ナノチューブ間の引力・会合を効果的に抑え、未修飾で形態変化なく、温和・簡便・短時間の方法にて長期間安定な脂質ナノチューブの分散液を与えることを可能とするものである。また、この分散液の濃度を調整することにより、自発的に配向し、ネマチック液晶を与えることができることも判明した。   As a result of intensive studies to achieve the above object, the present inventors selected an organic solvent having a specific density and refractive index as a dispersion medium, thereby maintaining the shape of the lipid nanotube for a long time. It was found that a dispersion capable of maintaining a good dispersion state can be realized. In other words, by matching the density and refractive index of the organic solvent used as the dispersion medium with the lipid nanotubes to be dispersed, the attractive force / association between the lipid nanotubes can be effectively suppressed, and there is no modification and no change in shape. It is possible to provide a dispersion of lipid nanotubes that is stable for a long time by the method of time. It has also been found that by adjusting the concentration of this dispersion, it can be spontaneously aligned to give a nematic liquid crystal.

本発明はこれらの知見に基づいて完成に至ったものであり、本発明によれば、以下の発明が提供される。
[1]N−グリコシド型糖脂質が自己集合してなる脂質ナノチューブの粉末を、密度及び屈折率が該脂質ナノチューブとマッチングした有機溶媒を分散媒に用いて分散させることを特徴とする脂質ナノチューブ分散液の製造方法。
[2]前記有機溶媒が、クロロベンゼン、2−クロロトルエン、フェノキシアセトン、4−メトシキ安息香酸エチルエステルから選ばれえることを特徴とする上記[1]の脂質ナノチューブの分散方法。
[3]N−グリコシド型糖脂質が自己集合してなる脂質ナノチューブの粉末が、密度及び屈折率を該脂質ナノチューブとマッチングさせた有機溶媒からなる分散媒中に分散していることを特徴とする脂質ナノチューブ分散液。
[4]前記有機溶媒が、クロロベンゼン、2−クロロトルエン、フェノキシアセトン、4−メトシキ安息香酸エチルエステルから選ばれえることを特徴とする請求項5に記載の脂質ナノチューブ分散液。
[5]上記[3]又は[4]の脂質ナノチューブ分散液からなるネマチック液晶。
The present invention has been completed based on these findings, and according to the present invention, the following inventions are provided.
[1] Lipid nanotube dispersion characterized by dispersing lipid nanotube powder in which N-glycoside type glycolipids are self-assembled using an organic solvent whose density and refractive index match the lipid nanotube as a dispersion medium Liquid manufacturing method.
[2] The method for dispersing lipid nanotubes according to [1], wherein the organic solvent can be selected from chlorobenzene, 2-chlorotoluene, phenoxyacetone, and 4-methoxybenzoic acid ethyl ester.
[3] The lipid nanotube powder formed by self-assembling N-glycoside type glycolipid is dispersed in a dispersion medium composed of an organic solvent whose density and refractive index are matched with the lipid nanotube. Lipid nanotube dispersion.
[4] The lipid nanotube dispersion according to claim 5, wherein the organic solvent can be selected from chlorobenzene, 2-chlorotoluene, phenoxyacetone, and 4-methoxybenzoic acid ethyl ester.
[5] A nematic liquid crystal comprising the lipid nanotube dispersion liquid of [3] or [4].

本発明によれば、脂質ナノチューブ間の引力・会合を効果的に抑え、未修飾で形態変化なく、温和・簡便・短時間の方法にて長期間安定な脂質ナノチューブの分散液を与えることが可能となる。また、この分散液の濃度を調整することにより、自発的に配向し、ネマチック液晶を与えることができる。   INDUSTRIAL APPLICABILITY According to the present invention, it is possible to effectively suppress the attractive force / association between lipid nanotubes and to provide a stable dispersion of lipid nanotubes for a long period of time by a mild, simple, and short method without modification and without morphological change. It becomes. Also, by adjusting the concentration of this dispersion, it can be spontaneously aligned to give a nematic liquid crystal.

本発明の脂質ナノチューブ分散液を、交差偏光板を介して撮影した写真A photograph of the lipid nanotube dispersion of the present invention taken through a crossed polarizing plate 本発明の脂質ナノチューブ分散液からなるネマチック液晶の偏光顕微鏡写真Polarized light micrograph of nematic liquid crystal comprising lipid nanotube dispersion of the present invention 本発明の脂質ナノチューブ分散液からなるネマチック液晶の電子顕微鏡写真Electron micrograph of nematic liquid crystal comprising lipid nanotube dispersion of the present invention 本発明の脂質ナノチューブ分散液からなるネマチック液晶を石英キャピラリー中に流動配向させた様子を撮影した写真A photograph of a nematic liquid crystal composed of a lipid nanotube dispersion of the present invention flow-oriented in a quartz capillary

本発明の脂質ナノチューブについて述べる。
本発明の脂質ナノチューブは、N−グリコシド型糖脂質が自己集合してなる有機ナノチューブであり、好ましくは、有機溶媒中で自己集合した、水を含まないものが用いられる。
The lipid nanotube of the present invention will be described.
The lipid nanotubes of the present invention are organic nanotubes in which N-glycoside type glycolipids are self-assembled, and preferably those that are self-assembled in an organic solvent and do not contain water.

上記N−グリコシド型糖脂質は、アグリコンとして不飽和炭化水素基を有するN−グリコシド型糖脂質、すなわち一般式(1)
G−NHCO−R (1)
で表わされるN−グリコシド型糖脂質であり、これを原料として無水有機ナノチューブを製造することができる。
この一般式(1)中のGは、糖のアノマー炭素原子に結合するヘミアセタール水酸基を除いた糖残基であり、この糖としては、例えば、グルコース、ガラクトース、マルトース、ラクトース、セロビオース、及びキトビオースが挙げられ、好ましくはグルコピラノースである。この糖は単糖又はオリゴ糖、好ましくは単糖である。この糖残基はD、L型、ラセミ体のいずれであってもよいが、天然由来のものは通常D型である。さらに、アルドピラノシル基においては、アノマー炭素原子は不斉炭素原子であるので、α−アノマー及びβ−アノマーが存在するが、α−アノマー及びβ−アノマー及びそれらの混合物のいずれであってもよい。とくにGがD−グルコピラノシル基、D−ガラクトピラノシル基、特にD−グルコピラノシル基であるものが、原料の入手の点で容易で製造しやすいので好適である。
また、上記一般式(1)中のRは、不飽和炭化水素基であり、好ましくは直鎖であり、更に好ましくは不飽和結合として3個以下の二重結合を含む。またRの炭素数は10〜39、好ましくは15〜20、より好ましくは17である。このような炭化水素基としては、ウンデシル基、ドデシル基、トリデシル基、テトラデシル基、ペンタデシル基、ヘキサデシル基、ヘプタデシル基、オクタデシル基、ノナデシル基、エイコシル基、ヘネイコシル基、ドコシル基、トリコシル基、テトラコシル基、ペンタコシル基、ヘキサコシル基、ヘプタコシル基、及びオクタコシル基などに不飽和結合としてモノエン、ジエン又はトリエン部分などを含むものが挙げられる。
The N-glycoside glycolipid is an N-glycoside glycolipid having an unsaturated hydrocarbon group as an aglycone, that is, the general formula (1)
G-NHCO-R 1 (1)
N-glycoside type glycolipid represented by the above, and anhydrous organic nanotubes can be produced using this as a raw material.
G in the general formula (1) is a sugar residue excluding the hemiacetal hydroxyl group bonded to the anomeric carbon atom of the sugar. Examples of the sugar include glucose, galactose, maltose, lactose, cellobiose, and chitobiose. Preferably, it is glucopyranose. The sugar is a monosaccharide or oligosaccharide, preferably a monosaccharide. The sugar residue may be D, L, or racemic, but naturally derived is usually D. Furthermore, in the aldopyranosyl group, since the anomeric carbon atom is an asymmetric carbon atom, there are α-anomers and β-anomers, but any of α-anomers, β-anomers and mixtures thereof may be used. In particular, those in which G is a D-glucopyranosyl group, a D-galactopyranosyl group, particularly a D-glucopyranosyl group are preferred because they are easy to produce and easy to produce.
R 1 in the general formula (1) is an unsaturated hydrocarbon group, preferably a straight chain, and more preferably 3 or less double bonds as an unsaturated bond. R has 10 to 39 carbon atoms, preferably 15 to 20 carbon atoms, and more preferably 17 carbon atoms. Such hydrocarbon groups include undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl , A pentacosyl group, a hexacosyl group, a heptacosyl group, an octacosyl group, and the like that include a monoene, diene, or triene moiety as an unsaturated bond.

次に、このN−グリコシド型糖脂質を用いて脂質ナノチューブを製造する方法について述べる。
まず、有機溶媒にN−グリコシド型糖脂質を溶解させて溶液を調製する。この有機溶媒は沸点以下に加温する。この溶液中のN−グリコシド型糖脂質の濃度は高いほど好ましく、飽和であることが最も好ましい。
この有機溶媒としては、沸点が120℃以下であるアルコール類又は沸点が120℃以下である環状エーテル類を用いることができるが、好ましくは、メタノールが用いられる。
調製したN−グリコシド型糖脂質の溶液を徐冷して、室温下に静置して無水有機ナノチューブを生成させる。徐冷十数時間〜数日間経過後、溶液から中空繊維状物質が析出してくる。
Next, a method for producing lipid nanotubes using this N-glycoside type glycolipid will be described.
First, an N-glycoside type glycolipid is dissolved in an organic solvent to prepare a solution. This organic solvent is heated below the boiling point. The concentration of the N-glycoside glycolipid in this solution is preferably as high as possible, and most preferably saturated.
As the organic solvent, alcohols having a boiling point of 120 ° C. or lower or cyclic ethers having a boiling point of 120 ° C. or lower can be used, and methanol is preferably used.
The prepared N-glycoside glycolipid solution is slowly cooled and allowed to stand at room temperature to produce anhydrous organic nanotubes. After gradual cooling for a few dozen hours to several days, the hollow fiber material precipitates from the solution.

別法として、上記と同様の有機溶媒にN−グリコシド型糖脂質を溶解させて溶液を調製する。この有機溶媒を使用するにあたっては特に加温を要しない。この溶液中のN−グリコシド型糖脂質の濃度は高いほど好ましく、飽和であることが最も好ましい。
次に、この溶液を濃縮する。例えば、この溶液をエバポレーターを用いて、蒸発温度は好ましくは室温〜低真空圧力下での沸点以下、圧力5〜10KPaで濃縮乾固する。
その結果、各有機溶媒に対する溶解度に依存して、溶液から無水有機ナノチューブが析出してくる。
Alternatively, a solution is prepared by dissolving N-glycoside glycolipid in the same organic solvent as described above. When using this organic solvent, no particular heating is required. The concentration of the N-glycoside glycolipid in this solution is preferably as high as possible, and most preferably saturated.
The solution is then concentrated. For example, this solution is concentrated and dried using an evaporator at an evaporation temperature of preferably room temperature to a boiling point under a low vacuum pressure and a pressure of 5 to 10 KPa.
As a result, depending on the solubility in each organic solvent, anhydrous organic nanotubes are precipitated from the solution.

更に別法として、上記と同様の有機溶媒にN−グリコシド型糖脂質を溶解させて溶液を調製する。この有機溶媒を使用するにあたっては特に加温を要しない。この溶液中のN−グリコシド型糖脂質の濃度は高いほど好ましく、飽和であることが最も好ましい。
次に、この溶液に、N−グリコシド型糖脂質に対する貧溶媒を、上記の既に加えてある有機溶媒に対して好ましくは少なくとも100容積%、より好ましくは少なくとも300容積%加える。
As another method, a solution is prepared by dissolving N-glycoside type glycolipid in an organic solvent similar to the above. When using this organic solvent, no particular heating is required. The concentration of the N-glycoside glycolipid in this solution is preferably as high as possible, and most preferably saturated.
Next, to this solution, a poor solvent for the N-glycoside type glycolipid is preferably added at least 100% by volume, more preferably at least 300% by volume with respect to the organic solvent already added.

次に、本発明の脂質ナノチューブの分散液の製造方法について述べる。
本発明では、分散媒中に脂質ナノチューブが沈んだり或いは浮いたりしないように、分散媒として、その密度が分散させる脂質ナノチューブとマッチングした有機溶媒を用いるとともに、その屈折率が脂質ナノチューブとマッチングしたものを用いることにより、脂質ナノチューブ間の引力・会合を効果的に抑え、長期間安定な脂質ナノチューブの分散液を与えることを可能にしたものである。
本発明において、分散媒として用いる有機溶媒は、上記の条件を満たすものであれば、単独溶媒であっても、或いは混合溶媒でもよいが、具体的には、単独溶媒として、クロロベンゼン、2−クロロトルエン、フェノキシアセトン、4−メトシキ安息香酸エチルエステル等が挙げられる。また、混合溶媒としては、これら溶媒の混合物及びベンゾニトリルと1,3−ジブロモプロパンの体積比9:1混合物等が挙げられる。
Next, a method for producing a dispersion of lipid nanotubes of the present invention will be described.
In the present invention, in order to prevent the lipid nanotubes from sinking or floating in the dispersion medium, an organic solvent matched with the lipid nanotubes whose density is dispersed is used as the dispersion medium, and the refractive index is matched with the lipid nanotubes. By using this, it is possible to effectively suppress the attractive force / association between lipid nanotubes and to provide a stable dispersion of lipid nanotubes for a long period of time.
In the present invention, the organic solvent used as the dispersion medium may be a single solvent or a mixed solvent as long as the above conditions are satisfied. Specifically, as the single solvent, chlorobenzene, 2-chloro Examples include toluene, phenoxyacetone, and 4-methoxybenzoic acid ethyl ester. Examples of the mixed solvent include a mixture of these solvents and a 9: 1 volume ratio mixture of benzonitrile and 1,3-dibromopropane.

本発明において、上記有機溶媒中に分散させる脂質ナノチューブ粉末の濃度が、1重量%未満で透明な分散液が得られる。また、濃度を調整することにより、具体的には、1〜10重量%で自発的に配向して、ネマチック液晶が得られる。
また、上記有機溶媒を用いて本発明の分散液を得るには、脂質ナノチューブ粉末を、該有機溶媒中において、バス型超音波装置により10〜60秒間超音波処理することが好ましい。
In the present invention, a transparent dispersion is obtained when the concentration of the lipid nanotube powder dispersed in the organic solvent is less than 1% by weight. Further, by adjusting the concentration, specifically, a nematic liquid crystal can be obtained by spontaneous alignment at 1 to 10% by weight.
Moreover, in order to obtain the dispersion liquid of this invention using the said organic solvent, it is preferable to ultrasonically process lipid nanotube powder for 10 to 60 second in this organic solvent with a bath type | mold ultrasonic device.

本発明の脂質ナノチューブは、その形態を保たれたままであると同時に、凝集も効果的に抑えられており、分散状態は3か月以上安定である。
また、本発明の脂質ナノチューブの分散液中では、機能性材料として例えばフラーレンを溶解させることができる。
The lipid nanotubes of the present invention are kept in their form, and at the same time, the aggregation is effectively suppressed, and the dispersion state is stable for 3 months or more.
In the lipid nanotube dispersion of the present invention, for example, fullerene can be dissolved as a functional material.

以下、本発明を実施例に基づいて説明するが、本発明はこの実施例に限定されるものではない。
以下の実施例では、下記のN−グリコシド型糖脂質を用いて、メタノール中からの析出により得られた脂質ナノチューブを用いた。
EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to this Example.
In the following examples, lipid nanotubes obtained by precipitation from methanol using the following N-glycoside glycolipids were used.

上記脂質ナノチューブ粉末を、様々な密度・屈折率をもつ有機溶媒に加え、10〜60秒の間、バス型ソニケーターで超音波処理した。
得られた分散状態を、目視・光学顕微鏡・90度方向の散乱光スペクトルにより観察評価するとともに、形態を電子顕微鏡観察した。
また、脂質ナノチューブ外表面の親水疎水性を評価するため、ガラス基板に分散液を展開して得られた膜について、水滴の接触角を測定した。
The lipid nanotube powder was added to an organic solvent having various densities and refractive indexes, and sonicated with a bath sonicator for 10 to 60 seconds.
The obtained dispersion state was observed and evaluated by visual observation, an optical microscope, and a scattered light spectrum in a 90-degree direction, and the form was observed with an electron microscope.
In addition, in order to evaluate the hydrophilicity / hydrophobicity of the outer surface of the lipid nanotube, the contact angle of water droplets was measured for a film obtained by spreading the dispersion on a glass substrate.

(結果)
密度の異なる各種有機溶媒の中で、上記脂質ナノチューブ粉末を分散させたところ、下記の表1に示すとおり、密度dが1.07g/mlより小さい分散媒中では沈み、dが1.13g/mlより大きい分散媒中では浮いた。
このことから、脂質ナノチューブの密度は1.10g/ml前後にあることがわかった。
(result)
When the above-mentioned lipid nanotube powder was dispersed in various organic solvents having different densities, as shown in Table 1 below, it sinks in a dispersion medium having a density d smaller than 1.07 g / ml, and d is 1.13 g / ml. It floated in a dispersion medium larger than ml.
From this, it was found that the density of lipid nanotubes was around 1.10 g / ml.

また、密度1.10g/ml前後の有機溶媒のうち、下記の表2に示すとおり、屈折率n=1.542〜1.546の溶媒(2−クロロトルエンなど)中で、0.1〜0.7wt%分散液は比較的透明度が高く3か月以上良好な分散状態を示した。   Further, among organic solvents having a density of around 1.10 g / ml, as shown in Table 2 below, in a solvent having a refractive index n = 1.542 to 1.546 (such as 2-chlorotoluene), 0.1 to The 0.7 wt% dispersion was relatively transparent and showed a good dispersion for 3 months or more.

さらに、1〜10重量%の分散液を調製したところ、粘度が若干高くなると同時に、交差偏光板のもと複屈折が観察された。
図1は、交差偏光板を介して分散液を撮影した写真であり、左側の写真は、2−クロロトルエン中に0.7重量%の脂質ナノチューブを分散させたものであり、右側の写真は、2−クロロトルエン中に4重量%の脂質ナノチューブを分散させたものであり、複屈折が観察される。
Furthermore, when a 1 to 10% by weight dispersion was prepared, the viscosity was slightly increased, and at the same time, birefringence was observed under the crossed polarizing plate.
FIG. 1 is a photograph of a dispersion taken through a crossed polarizing plate. The photograph on the left shows 0.7% by weight lipid nanotubes dispersed in 2-chlorotoluene, and the photograph on the right shows In addition, 4% by weight of lipid nanotubes are dispersed in 2-chlorotoluene, and birefringence is observed.

90度方向の散乱スペクトルによる観察とわずかに黄色く色づく透過光とから、分散液がMie散乱していることが示され、脂質ナノチューブ同士の会合も抑えられていることが示唆された。
さらに、電子顕微鏡観察から、脂質ナノチューブの形態は保たれていることが確認できた。
The observation by the 90-degree direction scattering spectrum and the slightly yellow colored transmitted light showed that the dispersion was Mie scattered, suggesting that the association of lipid nanotubes was also suppressed.
Furthermore, observation with an electron microscope confirmed that the morphology of the lipid nanotubes was maintained.

この分散液をスライドガラス上に広げ自然乾燥させたところ、脂質ナノチューブが密になった膜が得られた。この膜について水滴の接触角を測定したところ、83〜88度の値が得られた。この接触角の値は、ポリ塩化ビニルやポリスチレンの代表的値と同程度であり、脂質ナノチューブの表面が疎水的であることが示された。   When this dispersion was spread on a slide glass and allowed to dry naturally, a membrane in which lipid nanotubes were dense was obtained. When the contact angle of the water droplet was measured for this film, a value of 83 to 88 degrees was obtained. The value of this contact angle is comparable to typical values of polyvinyl chloride and polystyrene, indicating that the surface of the lipid nanotube is hydrophobic.

この1〜10重量%の分散液を偏光顕微鏡及び走査型電子顕微鏡で観察したところ、光学的に異方性のネマチック液晶のパターンが観察された。図2は、脂質ナノチューブ液晶(2―クロロトルエン中に2重量%)の偏光顕微鏡写真であり、図3は、その走査型電子顕微鏡写真である。
この液を内径0.5mmのキャピラリー中にインジェクションにより導入したところ、良好に流動配向したサンプルが得られた。図4は、脂質ナノチューブ液晶を石英キャピラリー中に流動配向させた様子を撮影した写真である。
When 1 to 10% by weight of the dispersion was observed with a polarizing microscope and a scanning electron microscope, an optically anisotropic nematic liquid crystal pattern was observed. FIG. 2 is a polarization micrograph of lipid nanotube liquid crystal (2% by weight in 2-chlorotoluene), and FIG. 3 is a scanning electron micrograph thereof.
When this liquid was introduced into a capillary having an inner diameter of 0.5 mm by injection, a sample with good flow orientation was obtained. FIG. 4 is a photograph of a state in which lipid nanotube liquid crystal is flow-oriented in a quartz capillary.

これらの結果は、以下のように考察される。
有機溶媒中からの析出により得られた脂質ナノチューブは、疎水的な外表面をもっているために、適切な密度dをもつ有機溶媒中にある程度分散させることが可能である。さらに、有機溶媒の屈折率nを脂質ナノチューブの値に合致させることにより、脂質ナノチューブ間のファンデルワールス引力が小さくなり、脂質ナノチューブの分散性が高くなったと解釈できる。高軸比のコロイド粒子は、粒子間引力が小さい条件下ある濃度以上で排除体積効果により自発的にネマチック液晶になることが知られている。脂質ナノチューブについても形態を保ちつつ粒子間引力を抑えて分散させる条件を探索すれば、有機溶媒中での自発的なネマチック配向を実現できることが明らかになった。
These results are considered as follows.
Since the lipid nanotubes obtained by precipitation from an organic solvent have a hydrophobic outer surface, they can be dispersed to some extent in an organic solvent having an appropriate density d. Furthermore, by matching the refractive index n of the organic solvent with the value of the lipid nanotube, it can be interpreted that the van der Waals attractive force between the lipid nanotubes is reduced and the dispersibility of the lipid nanotubes is increased. It is known that colloidal particles with a high axial ratio spontaneously become nematic liquid crystals due to the excluded volume effect above a certain concentration under conditions where the attractive force between particles is small. It was clarified that spontaneous nematic orientation in an organic solvent can be realized by searching for the conditions for dispersing the lipid nanotubes while maintaining the shape while suppressing the attractive force between particles.

本発明の脂質ナノチューブの分散方法及びその分散液は、脂質ナノチューブの形態を変化することなく、長期間良好な分散状態を維持することが可能であり、有機溶媒中で脂質ナノチューブと機能性有機材料とを共存分散させ、複合材料を製造する技術、又は反応試剤と均一混合し反応させる技術、或いは液晶用偏光膜など光学的異方性材料を作成する技術に適用することができる。   The method for dispersing lipid nanotubes and the dispersion liquid thereof according to the present invention can maintain a good dispersion state for a long period of time without changing the shape of the lipid nanotubes, and lipid nanotubes and functional organic materials in an organic solvent Can be applied to a technique for producing a composite material, a technique for uniformly mixing and reacting with a reaction reagent, or a technique for producing an optically anisotropic material such as a polarizing film for liquid crystal.

Claims (5)

N−グリコシド型糖脂質が自己集合してなる脂質ナノチューブの粉末を、密度及び屈折率が該脂質ナノチューブとマッチングした有機溶媒を分散媒に用いて分散させることを特徴とする脂質ナノチューブ分散液の製造方法。   Production of lipid nanotube dispersion characterized by dispersing lipid nanotube powder self-assembled with N-glycoside type glycolipids using an organic solvent whose density and refractive index match the lipid nanotube as a dispersion medium Method. 前記有機溶媒が、クロロベンゼン、2−クロロトルエン、フェノキシアセトン、4−メトシキ安息香酸エチルエステルから選ばれえることを特徴とする請求項1に記載の脂質ナノチューブの分散方法。   The method for dispersing lipid nanotubes according to claim 1, wherein the organic solvent can be selected from chlorobenzene, 2-chlorotoluene, phenoxyacetone, and 4-methoxybenzoic acid ethyl ester. N−グリコシド型糖脂質が自己集合してなる脂質ナノチューブの粉末が、密度及び屈折率を該脂質ナノチューブとマッチングさせた有機溶媒からなる分散媒中に分散していることを特徴とする脂質ナノチューブ分散液。   Lipid nanotube dispersion characterized in that a lipid nanotube powder formed by self-assembly of N-glycoside type glycolipid is dispersed in a dispersion medium composed of an organic solvent whose density and refractive index are matched with the lipid nanotube. liquid. 前記有機溶媒が、クロロベンゼン、2−クロロトルエン、フェノキシアセトン、4−メトシキ安息香酸エチルエステルから選ばれえることを特徴とする請求項3に記載の脂質ナノチューブ分散液。   The lipid nanotube dispersion liquid according to claim 3, wherein the organic solvent can be selected from chlorobenzene, 2-chlorotoluene, phenoxyacetone, and 4-methoxybenzoic acid ethyl ester. 請求項3又は4に記載の脂質ナノチューブ分散液からなるネマチック液晶。   A nematic liquid crystal comprising the lipid nanotube dispersion liquid according to claim 3.
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JP2003315832A (en) * 2002-04-24 2003-11-06 Sharp Corp Liquid crystal display element
JP2004224717A (en) * 2003-01-22 2004-08-12 Japan Science & Technology Agency N-glycoside-type glycolipid and hollow fiber-like organic nanotube comprising the same
JP2008030185A (en) * 2006-06-14 2008-02-14 National Institute Of Advanced Industrial & Technology Hollow-fiber-like organic nanotube and process for production thereof

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* Cited by examiner, † Cited by third party
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JP2003315832A (en) * 2002-04-24 2003-11-06 Sharp Corp Liquid crystal display element
JP2004224717A (en) * 2003-01-22 2004-08-12 Japan Science & Technology Agency N-glycoside-type glycolipid and hollow fiber-like organic nanotube comprising the same
JP2008030185A (en) * 2006-06-14 2008-02-14 National Institute Of Advanced Industrial & Technology Hollow-fiber-like organic nanotube and process for production thereof

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