JPH11315150A - Functional cast film produced by molecular imprinting and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a functional cast film by an imprinting method without using a polymerization process, capable of easily increasing a binding capacity of recognition site to a guest and enabling easy preparation of cast film. SOLUTION: The production process for a functional, cast film includes (1) a process to produce a solution by mixing an aqueous solution of a 1st polymer having a bonding site to a template atom or molecule and a compound containing a template atom or molecule, a water-insoluble 2nd polymer having hydrophilic site, and a solvent capable of dissolving the 1st and the 2nd polymers, to cast the solution on a substrate and to evaporate the solvent to obtain a film composed of a blend of the 1st polymer and the 2nd polymer and having the template atom or molecule bonded to the bonding site and (2) a process to treat the film with an acid to remove the template atom or molecule from the bonding site and form a recognition site in the film composed of a space corresponding to the template atom or molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of functional films (membranes), and more particularly to a new functional cast film utilizing a molecular imprinting method and a method for producing the same.

[0002]

2. Description of the Related Art The molecular imprint method is a molecular design method in which a molecule (or atom) is used as a template to form a recognition site (site) capable of identifying the molecule or atom in a matrix. More specifically, molecular imprinting involves binding a molecule or atom (guest) having a particular spatial arrangement to a binding site in a matrix and then removing the guest from the space corresponding to that guest. To form a functional material that forms and immobilizes a recognition site consisting of a guest molecule or an atom or a similar substance used as a template. It is attracting attention as a new method that can produce various sensors, materials for chromatography, separation materials, catalysts, artificial antibodies, and the like without the necessity of.

Here, in the conventional molecular imprinting method, generally, a functional monomer is polymerized in the presence of a template molecule or an atom (guest), and the guest (molecule or atom) is polymerized.
Had formed a recognition site. The problem with this method is that it is generally difficult to manufacture because the desired recognition site must be formed while polymer is generated by polymerizing the monomer, and only the site formed on the surface of the obtained polymer is a guest molecule. Alternatively, it does not participate in the reversible attachment and detachment of atoms, so that the binding capacity to the guest is small, and it is difficult to observe the process of binding and dissociation of the guest spectroscopically.

In order to overcome these problems, a polymer having a binding site for a guest is used from the beginning without going through a polymerization process, and the binding capacity of a recognition site derived from the binding site is further increased. It is expected that, for example, a highly functional element in the form of a film (film) can be obtained relatively easily if such a device is devised, but such a technique has not been found.

HY Wang et al., "Langmuir, Vol. 13,
No. 20, 5396-5400 (1997) ", as a functional film by a molecular imprinting method without going through a polymerization process,
A cast film using a poly (acrylonitrile-acrylic acid) copolymer and allowing the carboxyl group of acrylic acid after template formation to recognize (identify) theophylline is described. However, the film described in this paper is based on Phase Inversion Coagulation.
The method for preparing the film and the method for increasing the binding capacity of the recognition site are complicated. In other words, in the method of Wang et al., A recognition site is formed by immersing the cast film in water to cause phase transition aggregation of the polymer, and by strictly controlling the conditions (eg, temperature) during this aggregation. It is stated that the binding capacity of the recognition site can be changed.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to simply increase the binding capacity of a recognition site (site) to a guest in producing a functional cast film by an imprinting method that does not go through a polymerization process. Can,
Moreover, the preparation of the cast film itself is to provide a simple technique.

[0007]

According to the present invention, there is provided a method for producing a cast film, which comprises: (1) a first polymer having a bonding site for a template atom or molecule; It was obtained by mixing an aqueous solution of a compound containing a template atom or molecule, a second polymer insoluble in water but having a hydrophilic portion, and a solvent capable of dissolving the first polymer and the second polymer. After casting the solution on the substrate, the solvent is evaporated to form a film comprising a polymer blend of the first polymer and the second polymer, wherein the template atom or molecule is bonded to the bonding site. (2) removing the template atoms or molecules from the binding sites by acid treatment of the film, Method characterized by comprising the step of forming a recognition site consisting of the space corresponding to the template atom or molecule. In the method for producing a cast film of the present invention, the template atom or molecule is generally a metal (metal ion), a nucleic acid base, or a nucleic acid base-like molecule.

In the method for producing a cast film of the present invention, the first polymer having a bonding site for a template atom or molecule is preferably a monomer unit selected from vinyl chloride, acrylonitrile, styrene or vinyl fluoride, and a carboxylic acid. , Amine, amide, amidine, hydroxamic acid, pyridine or boronic acid. In one particularly preferred embodiment of the method for producing a cast film of the present invention, the copolymer constituting the first polymer is a copolymer of vinyl chloride and acrylic acid, the template is copper, and the second The polymer is polypropylene glycol.

The present invention further provides a functional cast film produced by the method as described above and used for analysis or separation of templated atoms or molecules or their analogs.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a method for producing a functional film by using an imprinting method, which comprises a polymer having a film forming property and having a bonding site for atoms or molecules serving as a template. 1) and
When a polymer blend with a polymer that is insoluble in water but has a hydrophilic portion (second polymer) is used, a recognition site (recognition site) for guest atoms and molecules can be obtained by a simple casting operation and a solvent removal operation (evaporation). ) Is based on the discovery that a cast film having a very large binding capacity can be obtained.

The first polymer in the present invention, that is, the polymer having a binding site for a template atom or molecule, is generally known by forming a cast film by evaporating a solvent from a solution. By copolymerizing various polymers (for example, polyvinyl chloride, polystyrene, etc.),
One having a binding site for a template atom or molecule (host) is used. That is, a monomer unit selected from vinyl chloride, acrylonitrile, styrene or vinyl fluoride, and a monomer unit having a carboxylic acid, amine, amidine, hydroxamic acid, pyridine or boronic acid as a functional group capable of binding to a template atom or molecule. Use a copolymer. Examples of such copolymers include poly (vinyl chloride-acrylic acid) copolymer, poly (acrylonitrile-acrylic acid) copolymer, poly (styrene-vinyl benzoic acid) copolymer,
Poly (vinyl chloride-acrylamide) copolymer, poly (styrene-vinyl pyridine) copolymer and the like can be mentioned.

The composition ratio between the monomer units in the copolymer constituting the first polymer is not particularly limited, and is determined in consideration of the use of the functional cast film and the film forming property. The fraction of monomer units having a functional group capable of binding to a template atom or molecule is in the range of 0.02 to 0.1.

Examples of the polymer having a binding site for a template atom or molecule (first polymer) include, in addition to the above-mentioned copolymer, a polymer obtained by introducing an appropriate ligand into a film-forming polymer such as cellulose nitrate or cellulose acetate. Alternatively, those into which a functional group (for example, carboxylic acid) capable of binding to a template atom or molecule by an appropriate reaction can be used.

In the present invention, a cast film is prepared by blending a second polymer with a polymer having a binding site for a template atom or molecule (first polymer) as described above. Here, the second polymer used in the present invention is a polymer that is insoluble in water but contains a hydrophilic group such as an ether group, a hydroxyl group (hydroxyl group), or an ester group in the molecular structure. Examples of suitable polymers for use as such a second polymer include:
Examples thereof include polypropylene glycol and polymethyl methacrylate. Although the blend ratio of the first polymer and the second polymer is not particularly limited, generally, the blend ratio of the second polymer to the first polymer is 5 to 20%.
(Weight ratio).

In order to produce a functional film (membrane) by the imprint method according to the present invention, a metal (metal ion) or a nucleobase or nucleobase-like molecule is generally used as a template atom or molecule. The functional film obtained by the present invention can be used for analysis (detection), separation, and the like of such metals (metal ions), nucleic acid bases, and nucleic acid base-like molecules. The metal (metal ion) used as the template is not particularly limited, and various metals (metal ions) such as alkali metals, alkaline earth metals, and transition metals can be used.
²⁺ , Li ⁺ , Pb2 ⁺ , Fe2 ⁺ , Ni2 ⁺ , Co2 ⁺ , M
g ²⁺ , Ca ²⁺ , K ^{+ and the} like. As a template (template molecule), a nucleobase-like molecule other than nucleobases, that is, purine bases (adenine, guanine) and pyrimidine bases (thymine, cytosine, uracil) can also be used. Here, the nucleobase-like molecule refers to a molecule containing a purine structure or a pyrimidine base structure similar to a nucleobase, and examples thereof include theophylline, caffeine, theobromine, and kinetin.

In order to produce a cast film according to the present invention, first, a first polymer (for example, a poly (vinyl chloride-acrylic acid) copolymer) having a binding site for a template atom or molecule, a compound containing the template atom or molecule is used. An aqueous solution of (for example, a metal salt), a second polymer that is insoluble in water but has a hydrophilic portion (for example, polypropylene glycol), and a solvent that can dissolve the first polymer and the second polymer. The solution obtained by mixing is cast on a substrate. That is, the solution (cast solution)
Is cast on a smooth substrate (for example, a polyethylene plate or a glass plate), and then left for a predetermined time (in some cases, lightly heated) to evaporate the solvent.

As a result, a film made of a polymer blend of the first polymer and the second polymer is formed on the substrate, in which a template atom or molecule is bonded to a bonding site present in the first polymer. doing. FIG. 1 schematically illustrates such a process using copper ions as a template and carboxyl groups (for example, derived from acrylic acid constituting a poly (vinyl chloride-acrylic acid) copolymer) as binding sites. This is shown in FIG. As shown in FIG. 1A, a part of the matrix (polymer) is pre-organized by bonding two carboxyl groups to copper ions.

Next, the thus-obtained film is subjected to an acid treatment to remove template atoms or molecules from the binding site. As the acid used for this treatment, for example,
When the template is a metal (metal ion), use an acid having an anion corresponding to the metal salt used. When the template is a nucleobase or nucleobase-like molecule, use an acid such as acetic acid or trifluoroacetic acid. Used. By such treatment, a recognition site (site) consisting of a space corresponding to a template atom or molecule is formed and immobilized in the polymer film.
For example, referring to FIG. 1, the pre-organized part in the process (A) is held as it is [(B) in FIG.
See], a copper ion or a metal ion similar thereto is formed of two carboxyl groups, and a recognition site capable of recombining with a copper ion is formed (see FIG. 1 (c)).

According to the present invention, when a cast film is prepared based on the molecular imprinting method as described above, the guest () can be prepared by simply blending a polymer having a water-insoluble but hydrophilic portion with a matrix polymer. (Atom, molecule) binding capacity of the recognition site becomes extremely large. Although the reason for this has not yet been fully elucidated, blending such a second polymer increases the hydrophilicity of the system and increases the water solubility of the compound containing the template atom or molecule in the film pores. This is presumed to be due to sufficient permeation to improve the contact between the aqueous solution and the surface of the matrix polymer membrane.

As can be understood from the above description, according to the present invention, the binding capacity for the target guest atom or molecule can be obtained by a simple operation of casting a casting solution on a suitable substrate and then performing an acid treatment. And a porous cast film (membrane) having a large particle size can be obtained. In the film of the present invention which does not go through the polymerization process, it is easy to spectroscopically observe the bonding and dissociation of the guest.

The cast film of the present invention is porous and has a large binding capacity to a guest, and it is easy to spectroscopically measure the binding. Therefore, the cast film can be used as a highly sensitive sensor. For example, as shown in the examples below,
It can be applied as a new type of metal sensor. Further, the cast film of the present invention has a large binding capacity to a metal (metal ion), a nucleic acid base or a nucleic acid base-like molecule, and thus can be used as a separating material for separating them.

[0022]

The following examples are provided to further clarify the features of the present invention, but the present invention is not limited by these examples. Example: Preparation of cast film Poly (vinyl chloride-acrylic acid) as the first polymer
Copolymer [vinyl chloride: acrylic acid monomer ratio = 97.
5: 2.5, hereinafter referred to as poly (VC-co-AA)] and this poly (VC-co-AA)
As a second polymer, 10% by weight of PPG (polyethylene glycol) was dissolved in THF (tetrahydrofuran), and a copper nitrate solution was added thereto. This solution (cast solution) was cast on a smooth polyethylene plate,
By removing F by evaporation, a porous film was obtained.

The infrared absorption spectrum of this film was measured (COO ⁻ .Cu ²⁺ : 1620 cm ⁻¹ ), and the poly (VC-
The binding (complex formation) between the carboxyl group (binding site) and the copper ion (template) in (co-AA) was quantitatively evaluated. Next, the film was immersed in 0.1 mM nitric acid. The infrared absorption spectrum (1620 cm ^-1 ) was measured during the acid treatment, and it was confirmed that the peak intensity was reduced and the imprinted copper (copper ion) was desorbed by immersion for 60 hours. .

As described above, in addition to the cast film using copper as a mold (Cu-imprint film: No. 1), a cast film using lithium as a mold (Li-imprint film: No. 1) is produced by the same operation. 2) was prepared.
Furthermore, for comparison, a cast film using copper as a template [Cu-imprint (no P)) was prepared from a casting solution using only poly (PV-co-AA) and not blending PPG.
PG) film: No. 3] and a cast film (non-imprint film: non-imprinted film) from a casting solution containing only poly (PV-co-AA) and PPG without containing a metal salt.
No. 4) was also prepared. The compositions of these casting solutions are summarized in Table 1.

[0025]

[Table 1]

Example 2 Recombination Test The cast film prepared in Example 1 was immersed in a 0.1 M aqueous solution of copper nitrate to evaluate its ability to recombine copper ions. The result is shown in FIG. Cu-imprint film prepared by blending PPG in casting solution (No.1)
Was found to have a much larger reversible binding capacity for copper ions than the Cu-imprint film (No. 3) prepared without blending PPG. Also, L
The i-imprint film (No. 2) also has some mold effect on copper ions.

As described above, the cast film of the present invention prepared so as to imprint the template from a casting solution in which the second polymer having a hydrophilic portion is blended in addition to the polymer having a binding site to the template is provided. It was found to have excellent recombination ability for the template and its similar guests.

[Brief description of the drawings]

FIG. 1 schematically illustrates a process in which a cast film is formed by a molecular imprinting method according to the present invention, and copper ions of a guest are bound, dissociated, and recombined.

FIG. 2 is a graph showing the recombination ability for copper ions as an example of the cast film of the present invention.

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Claims (5)

[Claims] 1. A first polymer having a binding site for a template atom or molecule, an aqueous solution of a compound containing the template atom or molecule, a second polymer insoluble in water but having a hydrophilic site, and The first polymer and the second
After casting a solution obtained by mixing a solvent capable of dissolving the polymer on a substrate, by evaporating the solvent,
Forming a cast film having a polymer blend of the first polymer and the second polymer, wherein the cast atoms or molecules are bonded to the bonding sites; and (2) acid-treating the film. Forming a recognition site comprising a space corresponding to the template atom or molecule in the film by removing the template atom or molecule from the binding site. . 2. The method for producing a cast film according to claim 1, wherein the template atom or molecule is a metal, a nucleic acid base, or a nucleic acid base-like molecule. 3. The method according to claim 1, wherein the first polymer having a bonding site for a template atom or molecule is a monomer unit selected from vinyl chloride, acrylonitrile, styrene or vinyl fluoride, and a carboxylic acid, amine, amide, amidine,
3. The method for producing a cast film according to claim 2, comprising a copolymer with a monomer unit having hydroxamic acid, pyridine or boronic acid. 4. The method according to claim 1, wherein the copolymer constituting the first polymer is a copolymer of vinyl chloride and acrylic acid, the template is copper, and the second polymer is polypropylene glycol. The method for producing a cast film according to claim 3. 5. A functional cast film produced by the method according to claim 1, which is used for analysis or separation of atoms or molecules used as templates or analogs thereof.