JP2012029830A - Heparin coating and medical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heparin coating which is excellent in adhesive property to the surface of an medical device or others, in which the carrying quantity of heparin is large, and which is excellent in antithrombogenicity, and a medical instrument coated with the heparin coating.SOLUTION: In the heparin coating including a coating component comprising the heparin or the salt of the same and a polymer material, the polymer material is a blanched type polymer having a plurality of blanched chains and having 2-N,N-dimethylaminoethyl methacrylate and/or the derivative of the same as a polymerization main component, the concentration of the polymer material in the heparin coating is 0.05 to 0.3 wt.%, the weight ratio of the polymer material and the heparin or the salt of the same is 1/0.75 to 1/1.3.

Description

  The present invention can maintain excellent anticoagulability (antithrombogenicity) over a long period of time, and can be applied to living tissue or as a constituent material of various medical devices such as artificial organs and artificial blood vessels. The invention relates to a possible heparin coating and a medical device coated with this heparin coating.

  When blood comes into contact with foreign matter, it has a property of coagulating due to the action of various components in the blood. Therefore, constituent materials for medical devices used for parts that come into contact with blood, such as artificial hearts, artificial heart valves, artificial blood vessels, vascular catheters, cannulas, cardiopulmonary bypasses, vascular bypass tubes, aortic balloon pumping, transfusion devices and extracorporeal circulation circuits Is required to have high anticoagulability. However, many of the constituent materials of conventional medical devices are inevitably caused by blood coagulation when used for a long period of time, which is not sufficient in terms of anti-blood coagulation sustainability. In addition, when the above-mentioned medical device is used for a patient, an anticoagulant such as heparin is usually used in combination. However, for example, when heparin is administered systemically, there is a problem that the risk of generating a large number of bleeding foci increases.

  As a method for solving such a problem, various techniques for fixing heparin on the surface of the medical material or releasing it gradually have been proposed. For example, heparin is contacted with a polymer material having a cationic residue, and heparin is supported on the polymer material in an ionic bond form, and heparin or a copolymer of polyvinyl chloride and acrylic acid or methacrylic acid is used. Patent Document 1 discloses an antithrombogenic medical material for coating formed by ion-bonding the salt.

  The present applicants use, as such a coating material, a polymer material that is hydrophilic at a temperature lower than a predetermined temperature (T) and hydrophobic at a temperature higher than the predetermined temperature (T). Heparin coating agent in which heparin or a salt thereof was supported was applied for a patent (Patent Document 2).

  The polymer material used for this heparin coating agent contains a polymer composed of N-isopropylacrylamide as a branched chain, and this branched chain has a temperature dependency that becomes hydrophilic at low temperatures and hydrophobic at high temperatures. As a result, the polymer material has the temperature responsiveness. That is, since the polymer material is hydrophilic (water-soluble) at a temperature lower than a predetermined temperature, the polymer material is dissolved in water and applied to a living body or a medical device, and then the temperature is higher than the predetermined temperature. Thus, it can be made hydrophobic (water insoluble) and attached to a living body or a medical device. In addition, since this polymer material is a star polymer having a plurality of branched chains, its adhesion to the surface of a medical device or the like is higher than that of a linear polymer.

Japanese Patent No. 3341503 JP 2007-319534 A

  In Patent Document 1, a polyvinyl chloride- (meth) acrylic copolymer carrying heparin is dissolved in a solvent and applied to an object such as a catheter. As this solvent, an organic solvent such as tetrahydrofuran is used (paragraphs 0027 to 0028).

  When organic solvents are used in this way, they cannot be used for surface treatments such as hybrid tissues composed of cells and synthetic or biomaterials used in regenerative medicine, or living tissues removed from hosts (cells are killed by organic solvents, etc. To get injured). Some materials themselves are vulnerable to organic solvents (such as nitrocellulose). Alternatively, in the case of surface treatment of a medical device coated with a drug such as a drug-releasing stent, damage such as peeling off a polymer layer carrying the drug with an organic solvent may occur.

  Since the heparin coating agent described in Patent Document 2 uses water as a solvent, it has less influence on biological tissues and the like than when an organic solvent is used. However, the N-isopropylacrylamide is a structural unit. The branched chain contained is electrically neutral and has no or very little interaction with anionic heparin, so the amount of heparin that can be supported on the polymer material is not sufficient, and further improvement is desired. It is rare.

  The present invention eliminates the above-mentioned conventional problems, has excellent adhesion to the surface of medical devices, etc., has a large amount of heparin and has excellent antithrombotic properties, and adheres this heparin coating agent. An object is to provide a medical device.

  In order to solve the above problems, the present inventors have shown that 2-N, N-, which exhibits hydrophilicity at a predetermined temperature or lower, exhibits hydrophobicity at a predetermined temperature or higher, and is slightly cationic, in a process of repeated studies. Attempts were made to introduce dimethylaminoethyl methacrylate into the branched chain of the polymer material. In the case of a polymer material having 2-N, N-dimethylaminoethyl methacrylate as a constituent unit, the cationic 2-N, N-dimethylaminoethyl methacrylate unit contributes to the binding with heparin and increases the amount of heparin supported. can do.

  However, since this polymer material is easily hydrolyzed by an ester bond in a 2-N, N-dimethylaminoethyl methacrylate unit even in an aqueous solution at room temperature, a tertiary amine is eliminated. It was considered unsuitable as a polymer material for a heparin coating agent because it lost the property of dehydrosolvating and lost its hydrophobic property, and the produced carboxyl group electrostatically repels the heparin molecule.

  Accordingly, as a result of repeated studies on a method for suppressing hydrolysis of 2-N, N-dimethylaminoethyl methacrylate units, the present inventors have found that this polymer material has 2-N, N-dimethylaminoethyl methacrylate as a structural unit. It has been found that hydrolysis of 2-N, N-dimethylaminoethyl methacrylate units can be controlled by suppressing the mixing ratio between the concentration of and the heparin.

  The present invention has been achieved on the basis of such findings, and the gist thereof is as follows.

  The heparin coating agent of the present invention (Claim 1) is a heparin coating agent comprising a coating component comprising heparin or a salt thereof and a polymer material, wherein the polymer material comprises 2-N, N-dimethylaminoethyl methacrylate and / or Or a branched polymer having a plurality of branched chains whose main component is a derivative thereof, the concentration of the polymer material in the heparin coating agent being 0.05 to 0.3% by weight, The weight ratio with heparin or a salt thereof is 1 / 0.75 to 1 / 1.3.

  The heparin coating agent according to claim 2 is the heparin coating agent according to claim 1, wherein the molecular weight of 2-N, N-dimethylaminoethyl methacrylate and / or its derivative unit per one branched chain is the molecular weight per one branched chain. It is characterized by being 90% or more.

  The heparin coating agent according to claim 3 is characterized in that, in claim 1 or 2, the branched chain consists only of 2-N, N-dimethylaminoethyl methacrylate and / or a derivative unit thereof.

  The heparin coating agent according to claim 4 is the aqueous solution according to any one of claims 1 to 3, which is an aqueous solution containing the coating component.

  A heparin coating agent according to claim 5 is the heparin coating agent according to any one of claims 1 to 4, wherein the polymer material is a compound having three or more N, N-disubstituted dithiocarbamylmethyl groups in the same molecule. This is a branched polymer obtained by subjecting at least 2-N, N-dimethylaminoethyl methacrylate and / or a derivative thereof to light irradiation living polymerization.

  The heparin coating agent according to claim 6 is the heparin coating agent according to claim 5, wherein the compound having three or more N, N-disubstituted dithiocarbamylmethyl groups in the same molecule has a benzene ring as a nucleus and the nucleus as a branched chain. Three or more of the N, N-disubstituted dithiocarbamylmethyl groups are bonded.

  The heparin coating agent according to claim 7 is the heparin coating agent according to any one of claims 1 to 6, wherein the molecular weight of the polymer material is 5,000 to 500,000.

  The heparin coating agent according to claim 8 is the heparin coating agent according to any one of claims 1 to 7, wherein the coating component is hydrophilic at a temperature lower than a predetermined temperature (T) and is higher than the predetermined temperature (T). It is characterized by being hydrophobic at temperature.

  The heparin coating agent according to claim 9 is characterized in that, in claim 8, the predetermined temperature (T) is a temperature between 25-37 ° C.

  A medical device of the present invention (Claim 10) is one in which the heparin coating agent according to any one of Claims 1 to 9 is coated.

  In the present invention, 2-N, N-dimethylaminoethyl methacrylate and / or its derivative (hereinafter referred to as 2-N, N-dimethylaminoethyl methacrylate and / or derivative) in the heparin coating agent is simply referred to as “DMAEM”. The concentration of the polymer material composed of a branched polymer having a plurality of branched chains whose main component is polymerization) is 0.05 to 0.3% by weight, and this polymer material and heparin or its By controlling the weight ratio of the salt to 1 / 0.75 to 1 / 1.3, hydrolysis of the DMAEM-derived structural unit (hereinafter sometimes referred to as “DMAEM unit”) in the branched chain is suppressed. A polymer material having a slight cationic property and having excellent heparin loading efficiency is applied to the heparin coating agent. Theft is possible.

  The details of the mechanism by which hydrolysis of DMAEM units can be suppressed by mixing the polymer material and heparin at the above weight ratio are not clear, but when mixed at a predetermined weight ratio, Due to the electrical affinity between the DMAEM unit and heparin, heparin is present in the vicinity of the DMAEM unit, and this heparin inhibits the access of water molecules, and as a result, hydrolysis is unlikely to occur. .

  In the present invention, the molecular weight of the DMAEM unit per one branched chain is preferably 90% or more of the molecular weight per one branched chain (Claim 2). In particular, the branched chain includes only the DMAEM unit. (Claim 3) The greater the amount of DMAEM units contained in the branched chain, the higher the cationicity of the branched chain, thereby improving the affinity with anionic heparin and increasing the amount of heparin supported by the polymer material.

  The heparin coating agent of the present invention can be an aqueous solution in which a coating component, which is a composite of a polymer material and heparin, is dissolved in water (Claim 4). It is possible to reduce the influence on the living body as non-use.

  The polymer material used in the present invention is a branched polymer in which a compound having three or more N, N-disubstituted dithiocarbamylmethyl groups in the same molecule is used as an iniferter, and at least DMAEM is subjected to light irradiation living polymerization. Preferably, the compound having 3 or more N, N-disubstituted dithiocarbamylmethyl groups in the same molecule has a benzene ring as a nucleus and 3 or more as branched chains in this nucleus. Those having an N, N-disubstituted dithiocarbamylmethyl group bonded thereto are preferred (Claim 6).

  The molecular weight of the polymer material used in the present invention is preferably 5,000 to 500,000 (Claim 7). If the molecular weight of the polymer material is within this range, the amount of heparin supported can be sufficient, and the adhesion of the heparin coating agent to a medical device or the like can be improved.

  The coating component according to the present invention is preferably hydrophilic at a temperature lower than a predetermined temperature (T), and preferably hydrophobic at a temperature higher than the predetermined temperature (T). (T) is preferably a temperature of 25 to 37 ° C. (Claim 9).

  The medical device of the present invention (Claim 10) is a medical device coated with the heparin coating agent of the present invention, and is excellent in adhesion and long-term stability of the heparin coating agent. Property) can be maintained over a long period of time. This medical device is useful as various medical devices such as artificial organs and artificial blood vessels.

It is a graph which shows the relationship between the temperature and light transmittance of a 6-branch polymer solution. It is a graph which shows the relationship between the temperature of a composite_body | complex, and light transmittance. It is a photograph which shows the antithrombogenic experimental result of an Example and a comparative example.

  Hereinafter, embodiments of the present invention will be described in detail.

[Heparin coating agent]
The heparin coating agent of the present invention is a coating comprising a polymer material having a plurality of branched chains mainly composed of 2-N, N-dimethylaminoethyl methacrylate and / or a derivative thereof (DMAEM), and heparin or a salt thereof. And a concentration of the polymer material in the heparin coating agent is 0.05 to 0.3% by weight, and a weight ratio of the polymer material to heparin or a salt thereof is 1 / 0.75. It is characterized by being -1 / 1.3.

  According to the present invention, as described above, hydrolysis of the structural unit derived from DMAEM can be suppressed. As a result, the coating component becomes hydrophobic, so that the surface of the medical device is stable over a long period of time. It becomes possible to adhere to. Further, a sufficient amount of heparin can be stably supported by the cationic DMAEM unit.

  In the present invention, the concentration of the polymer material in the heparin coating agent is preferably about 0.05 to 0.3% by weight, particularly about 0.05 to 0.15% by weight. When the concentration of the polymer material in the heparin coating agent is lower than the above lower limit, a uniform coating film cannot be obtained. When the concentration is higher than the above upper limit, the polymer material and heparin are combined in the weight described below. Even if it mixes by ratio, hydrolysis of a DMAEM unit cannot be suppressed. When the concentration of the polymer material in the heparin coating agent is within the above range, hydrolysis of DMAEM units is effectively suppressed, and handling property when applying the heparin coating agent is good, and a thin and uniform coating film is formed. Can be formed.

<Coating ingredients>
The weight ratio of the polymer material constituting the coating component according to the present invention to heparin or a salt thereof is preferably about 1 / 0.75 to 1 / 1.3, particularly about 1 / 0.85 to 1 / 1.15. When this weight ratio is outside the above range, hydrolysis of DMAEM units in the polymer material cannot be sufficiently suppressed. Moreover, when there is little heparin or its salt, an antithrombotic effect cannot fully be acquired, and when heparin or its salt is too much, manufacturing cost will rise. By setting the weight ratio of the polymer material to heparin or a salt thereof within the above range, it is possible to obtain sufficient antithrombogenicity while suppressing hydrolysis of the DMAEM unit.

  In order to prepare the coating component, heparin or a salt thereof is added to and mixed with a low temperature aqueous solution of the polymer material, and heparin or a salt thereof is supported on the polymer material.

  The coating component obtained by mixing the polymer material and heparin or a salt thereof at the predetermined concentration becomes hydrophilic at a temperature lower than the predetermined temperature (T) and becomes hydrophobic at a temperature higher than the predetermined temperature (T). . The predetermined temperature (T) is preferably 25 to 37 ° C, particularly 30 to 35 ° C.

  When the predetermined temperature is 30 ° C., an aqueous solution of a heparin coating agent at a temperature lower than 30 ° C., for example, about 10 to 25 ° C. is attached to a living body or a medical device by application or the like, and the temperature is higher than 30 ° C. By raising the temperature and drying as necessary, a water-insoluble coating carrying heparin or a salt thereof is formed. In the case of a living body, the temperature increase at this time may be performed by a non-contact type heating device such as infrared rays or illumination light, or may be performed using the body temperature of the living body.

≪Polymer material≫
The polymer material used in the present invention is preferably a compound obtained by using a compound having three or more N, N-disubstituted dithiocarbamylmethyl groups in the same molecule as an iniferter, and subjecting the iniferter to at least DMAEM light irradiation living polymerization.

  In this specification, the iniferter is a polymerization initiator that generates radicals upon irradiation with light, a function as a chain transfer agent, a function that bonds with the growth terminal to stop the growth, and a polymerization when light irradiation stops. It is a molecule that functions as a polymerization initiator / termination agent for stopping.

  As an aromatic compound having three or more N, N-disubstituted dithiocarbamylmethyl groups in the same molecule as an iniferter, the N, N-disubstituted dithiocarbamylmethyl group, preferably N, N A compound in which three or more dialkyldithiocarbamylmethyl groups are bonded as a branched chain is preferable, and specific examples are as follows. That is, the tri-branched compound is obtained by addition reaction of 1,3,5-tri (bromomethyl) benzene and sodium N, N-dialkyldithiocarbamate (sodium N, N-dialkyldithiocarbamate) in ethanol. 1,3,5-tri (N, N-dialkyldithiocarbamylmethyl) benzene, and four-branched compounds include 1,2,4,5-tetrakis (bromomethyl) benzene and N, N-dialkyldithiocarbamic acid 1,2,4,5-tetrakis (N, N-dialkyldithiocarbamylmethyl) benzene obtained by addition reaction of sodium (sodium N, N-dialkyldithiocarbamate) in ethanol, 6-branched compound As hexakis (bromomethyl) benzene and N, N-dialkyldithio Rubamin sodium (sodium N, N-dialkyldithiocarbamate) and the hexakis obtained by addition reaction in ethanol (N, N-dialkyldithiocarbamate carbamylmethyl) include benzene. Here, the alkyl group of the dialkyl moiety contained in the N, N-dialkyldithiocarbamylmethyl group is preferably an alkyl group having 2 to 18 carbon atoms such as an ethyl group, but is not limited to an alkyl group. It may be an aromatic hydrocarbon group such as a group. That is, not only N, N-dialkyldithiocarbamylmethyl group but also N, N-substituted by aliphatic hydrocarbon group and / or aromatic hydrocarbon group including N, N-diaryldithiocarbamylmethyl group and the like. A di-substituted dithiocarbamylmethyl group can achieve the object.

  The above iniferter is almost insoluble in polar solvents such as alcohol, but is easily soluble in nonpolar solvents. The nonpolar solvent is preferably a hydrocarbon, an alkyl halide or an alkylene halide, particularly preferably benzene, toluene, chloroform or methylene chloride, especially toluene.

  In order to react the iniferter with the DMAEM, a raw material solution containing the iniferter and the DMAEM is prepared and irradiated with light to thereby generate a reaction product in which DMAEM is bound to the iniferter.

  The concentration of DMAEM in the raw material solution is preferably 0.5 M or more, for example, 0.5 M to 2.5 M, and the concentration of iniferter is preferably about 1 to 20 mM.

The wavelength of the irradiated light is preferably 250 to 400 nm. For example, a fluorescent lamp, a short arc xenon lamp, a low pressure mercury lamp, a high pressure mercury lamp, or the like can be used. The irradiation time of the light depends on the irradiation intensity, about 1 to 90 minutes are preferred, about 1 to 60 minutes at a low irradiation intensity of about 1μW ^/ cm ² ~10mW ^/ cm 2 is particularly preferred. When light irradiation is performed using a commercially available fluorescent lamp, it is preferable to perform light irradiation for about 1 to 100 hours.

  By this light irradiation, the target branched polymer is produced in the reaction solution. Therefore, by purifying as necessary, a polymer chain composed of DMAEM units is introduced into the branched chain portion, and the end of the branched chain is N, A homopolymer which is an N-disubstituted dithiocarbamylmethyl group is obtained.

  The molecular weight per branched chain of this branched polymer is preferably about 100 to 60,000, particularly about 200 to 30,000. This molecular weight can be adjusted by controlling the light irradiation time. That is, by extending the reaction time, the polymerization reaction can be advanced to obtain a branched polymer having a large molecular weight.

  In addition, in this specification, molecular weight means the number average molecular weight of polyethylene glycol conversion by GPC (gel permeation chromatography).

  The branched chain of the branched polymer is preferably a homopolymer consisting of only one monomer having the above-mentioned DMAEM as a monomer. However, a block copolymer or a random copolymer in which one or more monomers different from DMAEM and DMAEM are introduced. It may be a copolymer.

As other monomers in this case, vinyl monomers such as acrylic acid derivatives and styrene derivatives are suitable. Specifically, N, N-dimethylacrylamide, methoxyethyl (meth) acrylate, 3-N, N- Dimethylaminopropylacrylamide CH ₂ = CHCONHC ₃ H ₆ N (CH ₃ ) ₂ , 4-N, N-dimethylaminostyrene, and at least one vinyl monomer selected from the group consisting of 4-aminostyrene derivatives In particular, cationic vinyl monomers such as 3-N, N-dimethylaminopropylacrylamide CH ₂ ═CHCONHC ₃ H ₆ N (CH ₃ ) ₂ are preferable. These vinyl monomers may be used alone or in combination of two or more.

  To react an iniferter with a different monomer from DMAME and DMAEM, a raw material solution containing monomers other than the iniferter, DMAEM, and DMAEM is prepared in the same manner as in the case of reacting the iniferter with DMAEM. Is irradiated with light to obtain a random copolymer in which monomers other than DMAEM and DMAEM are bonded to the iniferter.

In addition, to the above iniferter, first, DMAEM is block-polymerized to form a homopolymer, and then 3-N, N-dimethylaminopropylacrylamide is block-polymerized to the homopolymer, and the base end side of the branched chain is The block polymer of DMAEM may be a branched chain composed of 3-N, N-dimethylaminopropylacrylamide block polymer on the tip side of the branched chain. Thus, when making a branched chain into a block copolymer of two or more types of monomers, the order of polymerization with respect to the iniferter is arbitrary.
In either case, the end of the branched chain is an N, N-disubstituted dithiocarbamylmethyl group.

  As described above, when DMAEM and a monomer other than DMAEM are reacted, the molecular weight of DMAEM units per branched chain is 90% or more, particularly 95-100% of the molecular weight per branched chain. It is preferable that Since the DMAEM unit is cationic, the more DMAEM units contained in the branched chain, the higher the affinity between the polymer material and the anionic heparin, and the heparin loading can be increased. Thrombosis is improved.

  In the present invention, the polymer material functions as a carrier for heparin or a salt thereof, and also functions as an anchor for attachment to a medical device or the like, so that the branched polymer of the polymer material has more branched chains. Preferably, the number of branched chains is 4 or more, especially 6.

  Further, the molecular weight of the polymer material is preferably about 5,000 to 500,000, particularly about 25,000 to 150,000 in order to effectively obtain the above functions.

≪Heparin or its salt≫
As heparin, what is generally marketed can be used. Examples of heparin salts include heparin sodium and benzalkonium heparin. In the present invention, heparin and a heparin salt may be used in combination.

[Medical equipment]
Examples of the medical device of the present invention include artificial heart, artificial heart valve, artificial blood vessel, vascular catheter, vascular stent, cannula, heart-lung machine, blood vessel bypass tube, aortic balloon pumping, blood transfusion device, extracorporeal circuit, and other parts that come into contact with blood. Examples thereof include medical devices used in the above.

When the heparin coating agent of the present invention is applied to a medical device, it is preferable that about 0.1 to 30 mg of the heparin coating agent of the present invention is adhered to 1 cm ² of the surface of the medical device. This adhesion amount can be adjusted by the coating component concentration in the heparin coating agent, the coating amount of the coating agent (one coating amount, the number of coating times), the washing operation, and the like.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

(1) Synthesis of iniferter 1,2,3,4,5,6-hexakis (N, N-diethyldithiocarbamylmethyl) benzene as an iniferter was synthesized as follows.

  5.0 g of 1,2,3,4,5,6-hexakis (bromomethylbenzene) and 34.0 g of sodium N, N-diethyldithiocarbamate were added to 100 mL of ethanol, and the mixture was stirred at room temperature for 4 days in the dark. . The precipitate was filtered, poured into 3 L of methanol, stirred for 30 minutes, and then filtered. This operation was repeated a total of 4 times. Dissolve the precipitate in 200 mL of chloroform, add 100 mL of methanol, warm to 50 ° C., filter by heat, store in the refrigerator for 15 hours to recrystallize, wash the crystals with a large amount of methanol after filtration did. The crystals were dried at room temperature under reduced pressure to obtain white 1,2,3,4,5,6-hexakis (N, N-diethyldithiocarbamylmethyl) benzene needle-like crystals (yield 90%). This crystal was analyzed by high performance liquid chromatography, and it was confirmed that the raw material was not contained in the crystal and that the crystal was a single substance.

The measurement result of ¹ H-NMR (in CDCl ₃ ) is as follows: δ 1.26-1.31 ppm (t, 36H, CH ₂ CH ₃ ), δ 3.69-3.77 ppm (q, 12H, N (CH ₂ CH _{3 2} ), δ 3.99-4.07 ppm (q, 12H, N (CH ₂ CH ₃ ) ₂ ), δ 4.57 ppm (s, 12H, Ar—CH ₂ ).

(2) Synthesis of 6-branched polymer 1,2-3,4-5,6-hexakis [(N, N-diethyldithiocarbamyl) poly using 2-N, N-dimethylaminoethyl methacrylate as a monomer (2-N, N-dimethylaminoethyl methacrylate) methyl] benzene was synthesized.

  46.0 mg of 1,2,3,4,5,6-hexakis (N, N-diethyldithiocarbamylmethyl) benzene synthesized according to (1) above was dissolved in 20 mL of chloroform, and 2-N, N-dimethyl was dissolved. Aminoethyl methacrylate 8.0g was added and mixed, and the whole quantity was adjusted to 50 mL with chloroform. After purging with high-purity nitrogen gas (G1 grade, flow rate: 2 L / min) for 10 minutes with vigorous stirring in a 1 mm thick soft glass cell, the tube of a round tube fluorescent lamp (O-shaped) (Toshiba: FCL30L) The glass cell and the magnetic stirrer were placed inside, and the fluorescent lamp light was irradiated for 96 hours from the entire circumference of the side surface of the glass cell. The color of the solution after light irradiation was light yellow. The polymerization solution was concentrated with an evaporator, the polymer was reprecipitated with n-hexane, n-hexane was decanted, and the precipitate was dissolved in chloroform. The solvent was removed by evaporation to form a film on the inner wall surface of the flask. The film was purified by washing with a mixed solution of diethyl ether / n-hexane (v / v: 1/1) to obtain the intended 6-branched polymer. It was 26,000 (Mw / Mn = 2.0) when the number average molecular weight which used polyethylene glycol of this polymer as a standard substance was measured by GPC. The molecular weight per branched chain was calculated to be 4159.

(3) Cloud point evaluation 20 mg of the 6-branched polymer synthesized in (2) above was dissolved in water, immediately after dissolution (Experimental Example 1), 1 hour after dissolution (Experimental Example 2), and 3 hours later (Experimental example 3) The cloud point (LCST: Lower) of the said polymer was measured by measuring the light transmittance in 30-40 degreeC of the solution after 5 hours (experimental example 4), and 24 hours later (experimental example 5). Critical Solution Temperature) was determined. The results are shown in FIG.

  In all the experimental examples, the solution became cloudy due to an increase in temperature, which indicates that the polymer has temperature sensitivity. In addition, since the cloud point increased in proportion to the retention time from dissolution to measurement, and a volatile low molecular weight amine compound was formed in the solution with the passage of time, it was divided into 6 branches over time. It can be seen that the 2-N, N-dimethylaminoethyl methacrylate unit in the mold polymer is hydrolyzed in an aqueous solution and the desolvation property is gradually lost.

(4) Preparation of coating component and evaluation of cloud point Coating component (complex of 6-branched polymer and heparin) was prepared by mixing the 6-branched polymer synthesized in (2) and heparin in an aqueous solution. The cloud point was determined by measuring the light transmittance of this solution at 30 to 45 ° C. In forming the complex, an aqueous solution having a concentration of 40 mg / 2 mL was prepared as a 6-branched polymer solution. Moreover, the aqueous solution which changed the density | concentration in the range of 10-400 mg / 2mL was prepared as a heparin solution, respectively. Light transmittance was measured for a sample in which 2 mL of the 6-branched polymer solution and each heparin solution were mixed, and a sample consisting only of the 6-branched polymer solution, and the cloud point was determined. As a result, the sample with a higher heparin concentration had a higher cloud point, but the sample with a heparin concentration of 60 mg / 2 mL had a cloud point of less than 36 ° C. This is because in the case of a sample having a high concentration of heparin, heparin is present more in the sample than in the 6-branched polymer, so that the water solubility of the coating component is improved by the hydrophilic action of this excess heparin, resulting in cloudiness. Although the point rises, in samples with a heparin concentration of 60 mg / 2 mL or less, the number of excess heparin is small, and the clouding point is considered to be lower because the properties of the coating component appear stronger than the hydrophilic action of heparin. . Further, in the sample having a heparin concentration of 20 mg / 2 mL or less, the cloud point immediately after mixing was less than 36 ° C., but the cloud point increased with time and showed the same tendency as in Experimental Examples 1 to 5 above. .

(5) Change in cloud point of composite with time Of the composite formed in the above (4), the mixing ratio (weight ratio) of 6-branched polymer and heparin is 1.0 / 1.2. By measuring the relationship between temperature and light transmittance, the change in cloud point with time was observed. The results are shown in FIG.

  The cloud point immediately after mixing the 6-branch polymer solution and the heparin solution was higher than the cloud point of the 6-branch polymer solution alone. The cloud point after 5 hours from mixing and the cloud point after 24 hours were almost the same as the cloud point immediately after mixing. In this experiment, the cloud point after 24 hours after mixing was not measured, but the complex is stable in the state of being submerged in water, so it is stable even when it is attached to the surface of a medical device or the like. I think that.

  When the mixing ratio (weight ratio) of heparin to the 6-branched polymer was less than 0.75, the cloud point slightly increased with the passage of time. In particular, when the mixing ratio was 0.5, the cloud point immediately after mixing was 35 ° C., whereas the cloud point after 24 hours was 42 ° C. From this result, when the mixing ratio of heparin is reduced, the amount of heparin existing in the vicinity of the branched chain of the 6-branched polymer is reduced, and water molecules are easily brought close to the branched chain. As a result, hydrolysis is promoted. it is conceivable that. From the above examination, the mixing ratio (weight ratio) of heparin to the 6-branched polymer is preferably 0.75 or more, particularly 0.8 or more, and at the same time, the properties of the coating material are stronger than the hydrophilicity of heparin. It is preferably less than 1.5, particularly 1.3 or less, that is, within a range of 0.75 to 1.3, the hydrolysis of the branched chain of the 6-branched polymer is suppressed and stable. It is believed that a coating layer can be formed on the material surface.

(6) 6-branch polymer and composite coating (6-1) 6-branch polymer coating (Comparative Examples 1-1 to 1-3)
20 mg of the 6-branched polymer synthesized in the above (2) was dissolved in water, and the total amount was adjusted to 2 mL. 10 μL of this solution was uniformly cast onto a 2 × 3 cm square PE (polyethylene) film, and dried by a dryer to give a coating treatment (Comparative Example 1-2). This film surface was subjected to ESCA (X-ray photoelectron spectroscopy) analysis. Moreover, the same analysis was performed also about what processed the untreated PE film (Comparative Example 1-1) and the PE film of Comparative Example 1-2 for 20 minutes with 50 degreeC warm water (Comparative Example 1-3). . The results are shown in Table 1. In the table, N / C represents the abundance ratio of nitrogen atoms and carbon atoms, and S / C represents the abundance ratio of sulfur atoms and carbon atoms.

  From this result, it can be seen that the 6-branched polymer can be coated on a PE film.

(6-2) Coating of composite (Examples 1-1 and 1-2)
6 mg of 6-branched polymer and 40 mg of heparin were dissolved in water to adjust the total amount to 4 mL (hereinafter, this solution is referred to as “Coating Agent I”). Except for coating PE film with 10 μL of this coating agent I, the coating treatment was performed in the same manner as in Comparative Example 1-2, and the film surface was analyzed (Example 1-1). The same analysis was performed on the film of Example 1-1 washed with warm water as in Comparative Example 1-3. The results are shown in Table 2.

  When the PE film coated with the composite was analyzed, sulfur atoms were detected, indicating that the 6-branched polymer and heparin are attached to the surface of the PE film. Although not shown in Table 2, since the sulfur atom was detected even when the washing time with warm water was increased, the mixing ratio of the 6-branched polymer and heparin should be about 1/1. For example, it can be seen that the 6-branched polymer and heparin can be stably adhered to the surface of the PE film at a high density.

(7) Evaluation of antithrombotic properties After coating and drying the coating agent I in (6-2) on a PE film (Example 2-1) and a Si (silicon) film (Example 2-2), respectively. Each sample was further incubated in warm water at 37 ° C. for 24 hours and lightly rinsed with physiological saline.
As a comparative example, an untreated PE film (Comparative Example 2-1) and an untreated Si film (Comparative Example 2-2) were prepared.
By applying the collected human peripheral blood to these films promptly, incubating at 37 ° C, and rinsing lightly with physiological saline at an interval to observe the presence or absence of thrombus formed on the surface of each film. Antithrombogenicity was evaluated. The results are shown in FIG.

  It was confirmed that blood was coagulated on the film surface after 10 minutes for the untreated Si film and after 20 minutes for the untreated PE film. In both the Si film and the PE film that were coated with the heparin / 6-branched polymer composite, thrombus did not occur even after 30 minutes had passed since the blood was attached.

The coating agent I and the 6-branched polymer concentration were the same, and a coating agent having a mixing weight ratio of 6-branched polymer and heparin of 1 / 1.5 was prepared, and the coating treatment was performed in the same manner. Compared with Examples 2-1 and 2-2, the antithrombogenicity was significantly reduced. This is presumably because a part of the coating agent flowed out of the film surface when the coated film was lightly rinsed with 37 ° C. physiological saline. From this result, it can be determined that the physiological saline rinse at 37 ° C. is performed for a long period of time, that is, when it is actually exposed to the blood flow, the entire amount of the coating agent elutes and does not exhibit antithrombogenicity.
Similarly, when a coating agent having a mixing weight ratio of 6-branched polymer and heparin of 1 / 0.5 is prepared to evaluate antithrombogenicity, it is lower than those of Examples 2-1 and 2-2. The trend became prominent over time. This is presumably because a part of the branched chain of the 6-branched polymer was hydrolyzed and increased in hydrophilicity to diffuse and elute from the film surface.

(8) Evaluation of hydrolysis resistance A coating agent comprising an aqueous solution having a concentration of 6-branched polymers shown in Table 3 and a weight ratio of 6-branched polymers and heparin was prepared. Was evaluated for the hydrolysis resistance of the 6-branched polymer. That is, those exhibiting antithrombogenicity are resistant to hydrolysis (◯), and those not exhibiting antithrombogenicity are not resistant to hydrolysis (×). The results are shown in Table 3.

  From the results of Table 3, the heparin coating agent in which the concentration of the polymer material composed of the six-branched polymer and the weight ratio of the polymer material to heparin is within the scope of the present invention has hydrolysis resistance and antithrombotic properties. It turns out that it is effective as an adhesive coating agent.

Claims (10)

In a heparin coating agent comprising a coating component comprising heparin or a salt thereof and a polymer material,
The polymer material is a branched polymer having a plurality of branched chains having 2-N, N-dimethylaminoethyl methacrylate and / or a derivative thereof as a polymerization main component,
The concentration of the polymeric material in the heparin coating agent is 0.05-0.3 wt%;
A heparin coating agent, wherein the weight ratio of the polymer material to heparin or a salt thereof is 1 / 0.75 to 1 / 1.3.   2. The molecular weight of 2-N, N-dimethylaminoethyl methacrylate and / or a derivative unit thereof per one branched chain is 90% or more of the molecular weight per one branched chain according to claim 1. Heparin coating agent.   3. The heparin coating agent according to claim 1, wherein the branched chain is composed only of 2-N, N-dimethylaminoethyl methacrylate and / or a derivative unit thereof.   The heparin coating agent according to any one of claims 1 to 3, wherein the heparin coating agent is an aqueous solution containing the coating component.   5. The polymer material according to claim 1, wherein the polymer material is a compound having three or more N, N-disubstituted dithiocarbamylmethyl groups in the same molecule as an iniferter, and includes at least 2-N, N -A heparin coating agent, which is a branched polymer obtained by light-irradiating living polymerization of dimethylaminoethyl methacrylate and / or a derivative thereof.   6. The compound according to claim 5, wherein the compound having three or more N, N-disubstituted dithiocarbamylmethyl groups in the same molecule has a benzene ring as a nucleus and three or more N, N- A heparin coating agent, wherein a di-substituted dithiocarbamylmethyl group is bonded.   The heparin coating agent according to any one of claims 1 to 6, wherein the polymer material has a molecular weight of 5,000 to 500,000.   The coating component according to any one of claims 1 to 7, wherein the coating component is hydrophilic at a temperature lower than a predetermined temperature (T) and is hydrophobic at a temperature higher than the predetermined temperature (T). Heparin coating agent.   The heparin coating agent according to claim 8, wherein the predetermined temperature (T) is a temperature between 25 and 37 ° C.   A medical device coated with the heparin coating agent according to any one of claims 1 to 9.

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