JP3753633B2 - Hydrogen peroxide permselective membrane - Google Patents

Description

【００１１】
式（１）中、Ｒ¹およびＲ²は、それぞれ独立して、水素原子またはメチル基を表わす。ａおよびｄは、存在しなくてもよく、存在する場合には、それぞれ独立して、−Ｃ(Ｏ)Ｏ−、−ＣＯＮＨ−を表わす。Ａは下記の式（２）で示されるシロキサン部位を表わし、Ｄは炭素数１〜３のアルキル鎖の末端にあるエポキシ基またはアルデヒド基を表わす。Ｘは２５〜５０の整数を表わす。
【００１２】
【化２】

【００１３】
式（２）中、Ｒ³は炭素数１〜６のアルキル基を表わす。Ｒ⁴は水素原子またはメチル基を表わす。ｎは８〜１０の整数を表わし、また、ｍは１〜５の整数を表わす。
【００１４】
本発明で用いられる側鎖にシロキサン部位とエポキシ基またはアルデヒド基とを有するビニルポリマーの分子量は、特に制限されるものではないが、一般に数平均分子量として、１０，０００〜１，０００，０００の範囲にある。
【００１５】
また、本発明において用いられるアミノ基を有するポリマーとして好ましい例は、ポリアリルアミンまたはポリアミノ酸（例えば、ポリリジン）のような繰り返し単位毎にアミノ基が含有され且つ水溶性のポリマーである。
【００１６】
本発明に従いＬＢ法を利用して得られる超薄膜は、一般に、過酸化水素を選択的に透過させる選択透過性膜として使用されるが、特に、過酸化水素の発生量を電極電流の変化としてモニター（検出）する酵素センサー、例えばグルコースオキシダーゼやラクトースオキシダーゼを用いる糖センサーにおいて過酸化水素だけを通し共存する易酸化物質の透過を抑止するような電極のガード膜として用いられるのに適している。なお、このような酵素センサーに用いられる場合、電極には、本発明の過酸化水素選択透過性膜に加えて、酵素を固定化するための手段が採用される。
【００１７】
次に、本発明の選択透過性膜が得られる工程を図面に沿って説明する。
図１のイには、よく知られた典型的なＬＢトラフが示されている。図に示されるように、本発明に従う超薄膜を得るには、先ず、上述したような側鎖にシロキサン部位とエポキシ基またはアルデヒド基とを有するビニルポリマーをクロロホルムなどの溶媒に溶解し、マイクロシリンジなどで超純粋の水面上にゆっくり滴下して展開し溶媒が揮発するのを待つ。
【００１８】
このようにして、ポリマー主鎖が気液界面（水面）に沿って単分子層の厚みで二次元的に広がり、疎水性の高いシロキサン部位のある側鎖が水面上を空気相側に配向して並び、親水性または相対的に疎水性の低いエポキシ基（またはアルデヒド基）のある側鎖が水相側に配向して並んだ構造の膜が形成される。次に、バー（仕切り板：例えばテフロン製）を移動させて（図１のイの矢印の方向）、上記のごとき膜を圧縮する。この圧縮は、ＬＢ法の分野でよく知られているように、π−Ａ曲線で示される膜の表面圧が急な上昇を示すような密に詰まった状態、すなわち、凝縮単分子膜が形成される圧力になるまで実施する。
【００１９】
本発明の過酸化水素選択透過性膜を作製するポイントの一つは、シロキサン部位含有ポリマーがこのように密な単分子膜状に配向している状態で該ポリマーを二次元架橋することにある。このためには、前述したようなアミノ基を有するポリマー（例えば、ポリアリルアミン）の水溶液を、シロキサン部位含有ポリマーの膜を画定しているバー（仕切板）の外側からマイクロシリンジなどを用いて水面の下方（水相中）に注入する。この状態で暫く（例えば、５分間）放置すると、シロキサン部位含有ポリマーの側鎖にあるエポキシ基（またはアルデヒド基）と、アミノ基含有ポリマーのアミノ基とが反応して、気液界面で両ポリマーが二次元的に架橋した膜を得ることができる。このような二次元架橋の形成は、π−Ａ曲線で示される膜の表面圧の変化が不連続になり圧力上昇することから知ることができる。
【００２０】
本発明に従えば、以上のようにＬＢ膜を液中で化学結合により二次元架橋することにより、シロキサン系ポリマーから高密度で高強度の安定した超薄膜を得ることができ、しかもこの二次元架橋処理は該超薄膜に分子ふるい効果も付与して過酸化水素に対して高選択性の透過膜にする（後述の実施例参照）。
【００２１】
如上のようにＬＢ法に従い気液界面に凝縮単分子膜として形成され、更に、二次元架橋されて安定化したＬＢ膜（シロキサン含有ポリマーから成る超薄膜）は適当な基板上に移しとられる。この操作は、ＬＢ法の分野でよく知られているように基板を水中に浸漬して上下することによって行うこともできるが、本発明の膜を酵素センサーの電極のガード膜として使用する場合には、該電極をＬＢ膜に軽く当接するだけで電極の表面にＬＢ膜が移しとられる（図１のハ参照）ので、これを室温下に乾燥させる。
【００２２】
グルコースセンサーのような酵素センサーの電極として機能させるには、上述のように選択透過膜としてＬＢ膜を移しとった電極上に、適当な酵素固定化剤を介して酵素を固定化する。例えば、グルコースセンサーに使用する場合には、電極上に、酵素固定化剤としてポリカチオンであるポリアリルアミンとポリアニオンであるポリスチレンスルホン酸とから成るポリイオンコンプレックスを添加し、これにグルコースオキシダーゼ、さらに酵素−ポリアリルアミン間の架橋剤としてグルタルアルデヒドを添加する（図１のニ参照）。
【００２３】
【実施例】
以下に本発明の特徴をさらに具体的に示すため実施例を記すが、本発明はこの実施例によって制限されるものではない。
シロキサン含有ポリマーの合成
本発明に従う選択透過性膜を作製するため、下記の式（３）で表わされるシロキサン含有ポリマーを合成した。すなわち、ポリシロキサンを有するビニルモノマー（品名ＦＭ−０７１１ オルガノポリシロキサン、Ｍｎ＝１，０００、チッソ社製）（１）とメタクリル酸グリシジル（ＧＭＡ、ナカライテスク）（２）を原料とし、７．９０ｇ（７．８２ｍｍｏｌ）のモノマー（１）と２．７３ｇ（２０．０ｍｍｏｌ）のモノマー（２）、および１ｗｔ％量（０．１０６３ｇ）の重合開始剤アゾビスイソブチロニトリル（ＡＩＢＮ）を溶媒であるエタノール１０ｍｌに溶かしたモノマー溶液を、脱酸素雰囲気下において反応温度６０℃として３日間ラジカル重合を行った後、得られた重合物をメタノールを用いて精製を行った。重合物は元素分析、¹Ｈ−ＮＭＲによる分析の結果、仕込み通り２５：７５の比率であるコポリマーであった。また、数平均分子量は９８０００であった。
【００２４】
【化３】

【００２５】
選択透過膜および酵素固定化膜の作製
既述したように図１に示す工程に沿って選択透過膜および酵素固定化膜を作製した。
すなわち、上記のように合成した式（３）のポリマーをクロロホルムに溶解して超純水の水面上に展開し溶媒を揮発させた。気液界面に形成した膜を圧縮し、表面圧が１５ｍＮ／ｍの時にＰＡＡ（ポリアリルアミン：日東紡製、数平均分子量１００，０００）の水溶液を水面下に注入した後、５分間そのままにして水面下のエポキシ基とＰＡＡを反応させた。π−Ａ曲線を測定したところ、図２に示されるようにＰＡＡを注入すると膜の表面圧の変化が不連続になり、シロキサン含有ポリマー（ＰＳＣ）とＰＡＡが気液界面で二次元的に架橋したことが理解された。
【００２６】
以上のようにして調製した二次元架橋ＬＢ膜を白金電極上に移しとり、室温下で乾燥させることにより選択透過膜とした。
後述の酵素センサーとしての糖検出実験に用いるためには、このようにして得られた選択透過膜の上に酵素を固定した。固定化は、１０ｍＭのＰＡＡ（ポリアリルアミン）１０μｌ、０．１ｖ／ｖ％のＧＡ（グルタルアルデヒド）５μｌ、４ｗ／ｖ％のＧＯｘ（グルコースオキシダーゼ）５μｌ、および１０ｍＭのＰＳＳ（ポリスチレンスルホン酸：Aldrich製、分子量７０，０００）１０μｌを、この順に滴下し乾燥することにより行った。
【００２７】
電流測定実験
以上のようにして作製した選択透過膜および酵素固定化膜の選択透過性およびグルコースセンサーとしての応答性を調べる実験を行った。
比較のために、二次元架橋を行わない式（３）のポリマーのＬＢ膜から上記と同様に選択透過膜および酵素固定化膜を作製して実験に供した。さらに、式（３）のポリマーをクロロホルムに溶かした溶液を電極に塗布し溶媒を蒸発させて調製した膜（キャスト膜：膜厚約５μｍ）、および、電極上に既述の酵素固定化剤として用いたポリイオンコンプレックス（ＰＡＡ＋ＰＳＳ）のみを付着させたものについても同様の実験を行った。
【００２８】
電流測定は、参照電極として銀・塩化銀電極、対極として金ワイヤを用いて行った。上記のように作製した電極をリン酸緩衝水溶液（ｐＨ７．０、２０ｍｌ）に浸漬し、溶液を攪拌しながら、電極に＋０．６Ｖの電位を印加してサンプル添加時の酸化電流上昇値を測定することにより選択透過性および応答性を調べた。
【００２９】
測定結果を図３、図４および図５に示す。図３のＡは電極に単なるキャスト膜を被覆した場合であり、膜厚が大きいために、グルコースおよびビタミンＣ（ＡｓＡ）は勿論、過酸化水素でさえ透過できないことが理解される。また、図３のＢは電極にポリイオンコンプレックスのみを被覆した場合の結果を示しており、ポリイオンコンプレックスだけでは阻害物質の１種であるＡｓＡを充分にブロックできず幾分透過させていることが理解される。
【００３０】
図４のＢは、本発明に従い二次元架橋されたシロキサン含有ポリマーのＬＢ膜が電極上に移しとられて作製された選択透過膜の実験結果を示すものであり、阻害物質であるビタミンＣ（ＡｓＡ）を確実にブロックして過酸化水素を選択的に透過させている。これに対して、図４のＡは、架橋を行わないシロキサン含有ポリマーのＬＢ膜を電極上に転写した場合の結果を示しており、ビタミンＣの通過がブロックされておらず、架橋処理が過酸化水素の選択透過に関与していることが理解される。
【００３１】
図５は、本発明に従い架橋されたシロキサン含有ポリマーのＬＢ膜を電極に移しとって作製された選択透過膜に既述したようにグルコースオキシダーゼを固定化した酵素固定化膜の実験結果を示すものであり（Ｂ）、比較のために、未架橋のシロキサン含有ポリマーのＬＢ膜から同様に作製した酵素固定化膜の実験結果（Ａ）も示している。未架橋のシロキサン含有ポリマーを用いた酵素固定化膜ではグルコースもビタミンＣも同じくらいに応答しており選択性が見られない（Ａ）．これに対して、本発明に従う架橋ポリマーから作製された酵素固定化膜では（Ｂ）、ビタミンＣを添加しても検出されず、グルコースのみに対して選択的に応答しており、また、この系の応答がきわめて迅速であることも理解される。
【００３２】
【発明の効果】
本発明は、シロキサンを含有するポリマーから過酸化水素に対する選択透過性に優れセンサーに適用されたときに迅速な応答を示す安定な超薄膜の作製を可能にした。本発明の過酸化水素選択透過性幕は、例えば、糖センサーの電極の高選択性且つ高感度のガード膜として使用されることができる。
【図面の簡単な説明】
【図１】ＬＢ法を利用して本発明の選択透過性膜が作製される工程を示す。
【図２】本発明の選択透過性膜を作製するときのπ−Ａ曲線を示す。
【図３】比較のために行ったキャスト膜およびポリイオンコンプレックスのみを被覆した電極の透過性判定実験の結果を示す。
【図４】本発明に従い架橋されたシロキサン含有ポリマーのＬＢ膜から作製された選択透過性膜の透過性判定実験の結果を示し、比較のために未架橋のシロキサン含有ポリマーのＬＢ膜から作製された膜についての結果も示す。
【図５】本発明に従い架橋されたシロキサン含有ポリマーのＬＢ膜から作製された酵素固定化について調べた応答実験の結果を示し、比較のために未架橋のシロキサン含有ポリマーのＬＢ膜から作製された膜についての結果も示す。[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of gas permeable membranes, and particularly relates to a hydrogen peroxide selective permeable membrane made of a polymer having a siloxane moiety and suitable for use as a guard membrane of an electrode of a sugar sensor such as a glucose sensor. .
[0002]
[Prior art]
It is known that polysiloxane or a polymer containing a siloxane moiety is excellent in gas permeability, and is suitable as a selectively permeable membrane for oxygen, for example. Conventionally, polysiloxanes and siloxane-containing polymers used as gas permeable membranes are exclusively film-like products obtained by film-forming the polymers or coating them on a substrate from a colloidal solution. It is a thin film with a film thickness on the order of micrometers.
[0003]
Amperometric enzyme sensors that detect changes in the concentration of electrochemically active species associated with enzyme reactions as changes in electrode current are used in a wide range of fields. Typical examples include glucose sensors for measuring blood sugar. The sugar sensor. In such an enzyme sensor, the concentration increase / decrease of the target electrochemically active species (hydrogen peroxide in the case of a glucose sensor) is reliably detected and the permeation of the electrochemical species that interferes with the measurement is suppressed, and A permselective membrane that is as thin as possible is necessary so that the diffusion of the substrate proceeds rapidly and a quick response is shown. However, an ultrathin film that satisfies such a requirement is not known.
[0004]
[Problems to be solved by the invention]
The object of the present invention is to establish a new technique capable of obtaining an ultra-thin film that is suitable for use as a guard membrane of an electrode of an enzyme sensor and that is excellent in selective permeability to a specific gas and exhibits a quick response. There is.
[0005]
[Means for Solving the Problems]
The inventor of the present invention uses a LB (Langmuir-Blodgett) method to devise this to produce a stable ultrathin film having a molecular level thickness from a polysiloxane polymer. Successful achievement of the above objectives.
[0006]
Thus, according to the present invention, after a vinyl polymer having a siloxane moiety and an epoxy group or an aldehyde group in the side chain is developed and compressed on the water surface, a polymer having an amino group is injected below the water surface to inject the amino polymer. A hydrogen peroxide permselective membrane comprising a monomolecular membrane of a two-dimensionally crosslinked siloxane-containing vinyl polymer obtained by reacting a group with the epoxy group or aldehyde group is provided. The hydrogen peroxide permselective membrane of the present invention is particularly suitable for use as a guard membrane for an electrode of a sugar sensor such as a glucose sensor.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
As is well known, the LB method used in the practice of the present invention is to develop a substance having a hydrophilic part and a hydrophobic part on the gas-liquid interface (water surface) so that each of the hydrophilic part and the hydrophobic part is water. This is a method of forming an ultra-thin film by forming a film (monomolecular film: LB film) having a thickness of one molecule aligned in a phase and an air phase and transferring it to a solid substrate as necessary. However, there have been no examples in which a stable LB film has been produced from polysiloxane or a polymer having a siloxane moiety. This is probably because siloxane is very hydrophobic and too flexible.
[0008]
According to the present invention, as will be described in detail later, a polymer having a flexible and highly hydrophobic siloxane moiety is subjected to two-dimensional crosslinking in a state where the polymer is oriented in a monomolecular film form on the water surface. Thus, a stable ultrathin film can be produced.
[0009]
The vinyl polymer having a siloxane moiety and an epoxy group or an aldehyde group in the side chain used in the present invention can be generally expressed as a polymer having a repeating unit represented by the following formula (1).
[0010]
[Chemical 1]

[0011]
In formula (1), R ¹ and R ² each independently represents a hydrogen atom or a methyl group. a and d may not be present, and when present, each independently represents -C (O) O- or -CONH-. A represents a siloxane moiety represented by the following formula (2), and D represents an epoxy group or an aldehyde group at the terminal of an alkyl chain having 1 to 3 carbon atoms. X represents an integer of 25-50.
[0012]
[Chemical 2]

[0013]
In formula (2), R ³ represents an alkyl group having 1 to 6 carbon atoms. R ⁴ represents a hydrogen atom or a methyl group. n represents an integer of 8 to 10, and m represents an integer of 1 to 5.
[0014]
The molecular weight of the vinyl polymer having a siloxane moiety and an epoxy group or an aldehyde group in the side chain used in the present invention is not particularly limited, but is generally 10,000 to 1,000,000 as the number average molecular weight. Is in range.
[0015]
A preferred example of the polymer having an amino group used in the present invention is a water-soluble polymer containing an amino group for each repeating unit such as polyallylamine or polyamino acid (for example, polylysine).
[0016]
The ultrathin film obtained by using the LB method according to the present invention is generally used as a selectively permeable membrane that selectively permeates hydrogen peroxide. In particular, the amount of generated hydrogen peroxide is defined as a change in electrode current. In an enzyme sensor to be monitored (detected), for example, a sugar sensor using glucose oxidase or lactose oxidase, it is suitable for use as a guard film for an electrode that inhibits permeation of coexisting oxidizable substances through only hydrogen peroxide. In addition, when used for such an enzyme sensor, means for immobilizing the enzyme is employed for the electrode in addition to the hydrogen peroxide permselective membrane of the present invention.
[0017]
Next, the process for obtaining the selectively permeable membrane of the present invention will be described with reference to the drawings.
A well-known typical LB trough is shown in FIG. As shown in the figure, in order to obtain an ultrathin film according to the present invention, first, a vinyl polymer having a siloxane moiety and an epoxy group or an aldehyde group in the side chain as described above is dissolved in a solvent such as chloroform, and then a microsyringe. Then, slowly drop it onto ultrapure water and wait for the solvent to evaporate.
[0018]
In this way, the polymer main chain spreads two-dimensionally along the gas-liquid interface (water surface) with a monolayer thickness, and the side chains with highly hydrophobic siloxane sites are oriented on the water surface toward the air phase. A film having a structure in which side chains having epoxy groups (or aldehyde groups) having hydrophilicity or relatively low hydrophobicity are aligned to the aqueous phase side is formed. Next, the bar (partition plate: made of Teflon, for example) is moved (in the direction of the arrow in FIG. 1) to compress the membrane as described above. As is well known in the field of the LB method, this compression is performed in a tightly packed state where the surface pressure of the film indicated by the π-A curve shows a sudden rise, that is, a condensed monomolecular film is formed. Continue until the desired pressure is reached.
[0019]
One of the points for producing the hydrogen peroxide permselective membrane of the present invention is to two-dimensionally cross-link the polymer in such a state that the siloxane moiety-containing polymer is oriented in such a dense monomolecular film form. . For this purpose, an aqueous solution of an amino group-containing polymer (for example, polyallylamine) as described above is applied to the water surface using a microsyringe or the like from the outside of the bar (partition plate) that defines the siloxane site-containing polymer film. Inject below (in the aqueous phase). If left in this state for a while (for example, 5 minutes), the epoxy group (or aldehyde group) in the side chain of the siloxane moiety-containing polymer reacts with the amino group of the amino group-containing polymer, so that both polymers at the gas-liquid interface. Can be obtained as a two-dimensionally crosslinked film. The formation of such a two-dimensional bridge can be known from the fact that the change in the surface pressure of the film indicated by the π-A curve becomes discontinuous and the pressure rises.
[0020]
According to the present invention, the LB film is two-dimensionally cross-linked by chemical bonding in a liquid as described above, whereby a high-density, high-strength and stable ultrathin film can be obtained from a siloxane-based polymer. The cross-linking treatment imparts a molecular sieving effect to the ultra-thin film to make a permeable membrane highly selective with respect to hydrogen peroxide (see Examples described later).
[0021]
As described above, an LB film (an ultrathin film made of a siloxane-containing polymer) formed as a condensed monomolecular film at the gas-liquid interface according to the LB method and further stabilized by two-dimensional crosslinking is transferred onto a suitable substrate. This operation can be performed by immersing the substrate in water and moving up and down as is well known in the field of the LB method. However, when the membrane of the present invention is used as a guard membrane for an electrode of an enzyme sensor. Since the LB film is transferred to the surface of the electrode only by lightly contacting the electrode with the LB film (see FIG. 1C), this is dried at room temperature.
[0022]
In order to function as an electrode of an enzyme sensor such as a glucose sensor, an enzyme is immobilized via an appropriate enzyme immobilizing agent on the electrode having the LB membrane transferred as a selectively permeable membrane as described above. For example, when used for a glucose sensor, a polyion complex consisting of polyallylamine, which is a polycation, and polystyrene sulfonic acid, which is a polyanion, is added onto an electrode as an enzyme immobilizing agent, and glucose oxidase and further enzyme- Glutaraldehyde is added as a cross-linking agent between polyallylamines (see D in FIG. 1).
[0023]
【Example】
Examples are given below to illustrate the features of the present invention more specifically, but the present invention is not limited to these examples.
Synthesis of siloxane-containing polymer In order to produce a selectively permeable membrane according to the present invention, a siloxane-containing polymer represented by the following formula (3) was synthesized. Specifically, a vinyl monomer having a polysiloxane (product name FM-0711 organopolysiloxane, Mn = 1,000, manufactured by Chisso Corporation) (1) and glycidyl methacrylate (GMA, Nacalai Tesque) (2) are used as raw materials, and 7.90 g (7.82 mmol) of monomer (1), 2.73 g (20.0 mmol) of monomer (2), and 1 wt% (0.1063 g) of polymerization initiator azobisisobutyronitrile (AIBN) in a solvent. A monomer solution dissolved in 10 ml of ethanol was subjected to radical polymerization at a reaction temperature of 60 ° C. in a deoxygenated atmosphere for 3 days, and the resulting polymer was purified using methanol. As a result of elemental analysis and analysis by ¹ H-NMR, the polymer was a copolymer having a ratio of 25:75 as charged. The number average molecular weight was 98,000.
[0024]
[Chemical 3]

[0025]
Production of selectively permeable membrane and enzyme-immobilized membrane As described above, a selectively permeable membrane and an enzyme-immobilized membrane were produced according to the steps shown in Fig. 1.
That is, the polymer of the formula (3) synthesized as described above was dissolved in chloroform and developed on the surface of ultrapure water to volatilize the solvent. The membrane formed at the gas-liquid interface is compressed, and when the surface pressure is 15 mN / m, an aqueous solution of PAA (polyallylamine: manufactured by Nittobo, number average molecular weight 100,000) is injected under the surface of the water, and left for 5 minutes. The epoxy group under the water surface was reacted with PAA. When the π-A curve was measured, as shown in FIG. 2, when PAA was injected, the change in the surface pressure of the film became discontinuous, and the siloxane-containing polymer (PSC) and PAA cross-linked two-dimensionally at the gas-liquid interface. It was understood that
[0026]
The two-dimensional crosslinked LB membrane prepared as described above was transferred onto a platinum electrode and dried at room temperature to obtain a permselective membrane.
In order to use for the sugar detection experiment as the enzyme sensor described later, the enzyme was immobilized on the permselective membrane thus obtained. Immobilization was performed using 10 μl of 10 mM PAA (polyallylamine), 5 μl of 0.1 v / v% GA (glutaraldehyde), 5 μl of 4 w / v% GOx (glucose oxidase), and 10 mM PSS (polystyrene sulfonic acid: manufactured by Aldrich). , Molecular weight 70,000) was added dropwise in this order and dried.
[0027]
Current measurement experiment An experiment was conducted to examine the selective permeability of the permselective membrane and enzyme-immobilized membrane prepared as described above and the responsiveness as a glucose sensor.
For comparison, a permselective membrane and an enzyme-immobilized membrane were prepared from the polymer LB membrane of the formula (3) not subjected to two-dimensional crosslinking in the same manner as described above and used for the experiment. Furthermore, a film prepared by applying a solution of the polymer of formula (3) in chloroform to the electrode and evaporating the solvent (cast film: film thickness: about 5 μm), and the enzyme immobilizing agent described above on the electrode A similar experiment was performed on the sample to which only the used polyion complex (PAA + PSS) was attached.
[0028]
Current measurement was performed using a silver / silver chloride electrode as a reference electrode and a gold wire as a counter electrode. The electrode produced as described above is immersed in an aqueous phosphate buffer solution (pH 7.0, 20 ml), and while the solution is stirred, a potential of +0.6 V is applied to the electrode to measure the increase in oxidation current when the sample is added. Thus, selective permeability and responsiveness were examined.
[0029]
The measurement results are shown in FIG. 3, FIG. 4 and FIG. FIG. 3A shows a case where the electrode is covered with a simple cast film. Since the film thickness is large, it is understood that not only glucose and vitamin C (AsA) but also hydrogen peroxide cannot be permeated. FIG. 3B shows the result when the electrode is coated only with the polyion complex, and it is understood that the polyion complex alone does not sufficiently block AsA, which is one of the inhibitory substances, and allows some penetration. Is done.
[0030]
FIG. 4B shows the experimental results of a permselective membrane prepared by transferring an LB film of a siloxane-containing polymer that has been two-dimensionally cross-linked according to the present invention onto an electrode. Vitamin C ( AsA) is reliably blocked and hydrogen peroxide is selectively permeated. On the other hand, FIG. 4A shows the result when the LB film of the siloxane-containing polymer that is not crosslinked is transferred onto the electrode, and the passage of vitamin C is not blocked and the crosslinking treatment is excessive. It is understood that it is involved in the selective permeation of hydrogen oxide.
[0031]
FIG. 5 shows experimental results of an enzyme-immobilized membrane in which glucose oxidase is immobilized as described above in a selectively permeable membrane prepared by transferring an LB film of a siloxane-containing polymer crosslinked according to the present invention to an electrode. (B), and for comparison, an experimental result (A) of an enzyme-immobilized membrane similarly produced from an LB membrane of an uncrosslinked siloxane-containing polymer is also shown. In an enzyme-immobilized membrane using an uncrosslinked siloxane-containing polymer, glucose and vitamin C respond to the same extent, and no selectivity is observed (A). On the other hand, in the enzyme-immobilized membrane prepared from the crosslinked polymer according to the present invention (B), even when vitamin C is added, it is not detected and responds selectively only to glucose. It is also understood that the system response is very rapid.
[0032]
【The invention's effect】
The present invention has made it possible to produce a stable ultra-thin film having excellent permselectivity with respect to hydrogen peroxide from a polymer containing siloxane and showing a quick response when applied to a sensor. The hydrogen peroxide permselective curtain of the present invention can be used, for example, as a highly selective and sensitive guard film for an electrode of a sugar sensor.
[Brief description of the drawings]
FIG. 1 shows a process for producing a selectively permeable membrane of the present invention using an LB method.
FIG. 2 shows a π-A curve when producing a selectively permeable membrane of the present invention.
FIG. 3 shows the result of a permeability judgment experiment of an electrode coated only with a cast membrane and a polyion complex, which was performed for comparison.
FIG. 4 shows the results of a permeability determination experiment for a selectively permeable membrane made from a cross-linked siloxane-containing polymer LB membrane according to the present invention, and was made from an uncross-linked siloxane-containing polymer LB membrane for comparison. The results for the membranes are also shown.
FIG. 5 shows the results of a response experiment examining enzyme immobilization made from cross-linked siloxane-containing polymer LB films in accordance with the present invention, made from uncrosslinked siloxane-containing polymer LB films for comparison. The results for the membrane are also shown.

Claims (2)

A vinyl polymer having a siloxane moiety and an epoxy group or an aldehyde group in the side chain is developed on the water surface and compressed, and then the amino group and the epoxy group or aldehyde group are injected under the water surface by injecting the polymer having an amino group. A hydrogen peroxide permselective membrane comprising a monomolecular membrane of a two-dimensionally cross-linked siloxane-containing vinyl polymer obtained by reacting with a hydrogen peroxide. 2. The hydrogen peroxide permselective membrane according to claim 1, which is used as a guard membrane for an electrode of a sugar sensor.

Images