JPH0366904B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an antithrombotic material obtained by fixing a physiologically active substance to a polymeric substance, which is suitable for use in the medical field such as medical devices and artificial organs. [Prior Art] Blood coagulation caused when blood comes into contact with a foreign substance is a major obstacle in the development of medical devices such as vascular catheters and artificial organs such as artificial blood vessels and artificial kidneys. For this reason, active efforts are being made to research and develop better antithrombotic materials, but none have yet been obtained, and there is a great need for antithrombotic materials in the medical field. The medical polymer materials that have been studied so far have been found to be relatively difficult to activate blood coagulation system factors, or have low adhesion to blood components such as platelets and red blood cells, which can cause blood coagulation. It is well known that it has characteristics such as hardness. Medical materials of this type include silicone polymers and fluororesins, which have a hydrophobic surface and are said to be inert and do not stimulate the blood coagulation system, and polyvinyl alcohol and ethylene-vinyl, which are highly hydrophilic and have low stickiness to blood components. Alcohol copolymers, hydrophilic graft chains that suppress the adhesion of blood components (e.g. hydroxyethyl methacrylate), graft polymerization of polyacrylamide, etc. as base materials, and antithrombotic products with microphase separation structures. Segmented polyurethanes such as Biomer (registered trademark), which have improved properties, are known. However, these characteristics can only be exhibited when used for a short period of time, and when used for a long period of time, blood clots may form or calcification may occur, so it cannot be an effective antithrombotic material in the long term. Not yet. In addition, medical materials in which physiologically active substances such as substances that inhibit blood coagulation (such as heparin) and substances that dissolve coagulated blood (such as urokinase and streptokinase) are immobilized on the polymer surface are being considered. It's here. For example, immobilization of urokinase in Japanese Patent Publication No. 55-15224, Japanese Patent Publication No. 50-139174
Examples include immobilization of heparin as disclosed in Japanese Patent Application Laid-open No. 51-194. However, these have the disadvantage that the physiologically active substance having antithrombotic properties (hereinafter referred to as antithrombotic factor) is directly immobilized on the surface of the base material, so that its activity is not sufficiently expressed. In order for an antithrombotic factor to exhibit activity, it is necessary to maintain its three-dimensional structure (conformation), and an immobilization method that cannot maintain this conformation will not exhibit sufficient activity. In other words, it is difficult to maintain the effect over a long period of time simply by immobilizing antithrombotic factors on the surface of a base material, and from this point of view, no perfect result has been obtained yet. [Object of the Invention] As a result of various researches aimed at obtaining an antithrombotic material that is effective over a longer period of time, the present invention has been made to fix a physiologically active substance with antithrombotic properties to a hydrophilic material via a silane coupling agent. By doing so, they obtained the knowledge that they have superior antithrombotic properties compared to conventional products, and that the antithrombotic properties last for a long period of time.After conducting further studies, they were able to complete the present invention. [Structure of the Invention] That is, the present invention provides a hydrophilic material obtained by grafting polyethylene glycol onto a polymer substance,
This is an antithrombotic material characterized by immobilizing a physiologically active substance via a silane coupling agent having an amino group. As the polymer substance in the present invention, in addition to chlorosulfonated polymers such as chlorosulfonated polyethylene, chlorosulfonated polypropylene, and chlorosulfonated polystyrene, polyethylene, ethylene-vinyl acetate copolymer, polyurethane, polyamide, etc. can be used. Preferably, chlorosulfonated polymers are suitable. Furthermore, the method of grafting reaction of polyethylene glycol is not particularly limited, and may be any generally known method such as chemical reaction or radiation grafting. The silane coupling agent having an amino group used in the present invention is a silane compound represented by general formula (1). NH ₂ -R-Si-XnY _3-o ...(1) [wherein, 3 R: − [(CH ₂ ) _x −NH−] _n (CH ₂ ) _y − or −
CONH− [(CH ₂ ) _x −NH−] _n (CH ₂ ) _y − x, y: 0 or an integer of 20 or less m: 0 or an integer of 10 or less] Physiologically active substances include urokinase, streptokinase, heparin , TPA (teishu plasminogen activator), etc. are well known, but these can be used as the physiologically active substance in the present invention and are not particularly limited. As mentioned earlier, various studies have been made to immobilize physiologically active substances with antithrombotic properties, that is, antithrombotic factors, but these antithrombotic factors tend to become inactivated or detached. Therefore, it cannot be said that the antithrombotic properties are sufficient when used for a long period of time. Therefore, in the present invention, the material for immobilizing antithrombotic factors is itself highly hydrophilic, and the antithrombotic factors are efficiently immobilized thereon. The mechanism by which the material according to the present invention exhibits excellent antithrombotic properties is that the excluded volume effect of the graft chains made of polyethylene glycol is high, suppresses the adhesion of blood components, and inhibits blood coagulation. In addition to having antithrombotic properties, the degree of freedom of the graft chain is increased by using a silane coupling agent having an amino group when fixing the physiologically active substance to the graft chain. It is also presumed that this is because the active site of the antithrombotic factor immobilized in this state is not immobilized due to the motility of the graft chain, so that it can exhibit more effective antithrombotic properties. [Effects of the Invention] The antithrombotic material of the present invention can be processed into any shape by selecting a thermoplastic material as the hydrophilic base material, and can be processed into any shape, such as catheters, tubes, fibers, and films. It can be processed into beads, etc., and is suitable as a material for all kinds of medical devices such as artificial blood vessels and artificial organs that are used in long-term contact with blood. Examples will be described below. Example 1 A hydrophilic material (grafting rate 10%, manufactured by Sanyo Chemical Co., Ltd.) in which polyethylene glycol (degree of polymerization 6000) was grafted onto chlorosulfonated polyethylene was dissolved in tetrahydrofuran (THF) at a ratio of 5W/V%. did. This was casted on a flat glass shear tray and vacuum dried at 40°C for 1 day. Let this hydrophilic material film be (). On the other hand, as comparative materials, 40 parts of DOP, 10 parts of epoxidized soybean oil, 0.2 parts each of zinc stearate and calcium stearate, and 0.2 parts of stearic acid were added to 100 parts of vinyl chloride resin (Sumitomo Chemical Co., Ltd. SX-DH). A soft vinyl chloride resin to which was added was similarly dissolved in tetrahydrofuran and casted to obtain a film. This soft vinyl chloride resin film is referred to as (). The film in () is immersed in a 10% acetone solution of γ-aminopropyltrimethoxysilane (manufactured by Toray Silicone Co., Ltd.) and reacted at 50°C for 4 hours. After sequentially washing this with acetone, ethanol and pure water, 1-ethyl-3-
The mixture was added to a solution containing 15 mg/ml of (3dimethylaminopropyl)carbodiimide hydrochloric acid group and reacted at 40°C for 18 hours, followed by washing with water and drying to obtain a heparinized material (). Next, antithrombotic properties were evaluated using the method of Imai et al. using fresh dog blood. That is, 250 μ of fresh dog blood containing 10% citric acid was dropped onto a 30 mm square evaluation film, 25 μ of a 0.1M calcium chloride solution was immediately mixed therein, and a 15 mm square evaluation film was placed from above and incubated at 37°C. After 10 minutes, the sample was taken out and dried, the weight of the coagulated blood was measured, and the relative value was calculated based on the weight of the glass as 100%. The results are shown in Table 1, and it can be seen that the heparinized material according to the present invention exhibits good antithrombotic properties.

[Table] Example 2 The film () obtained in Example 1 was
(Aminoethyl)γ-aminopropylmethyldimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) in a 10% acetone solution and allowed to react at room temperature for 24 hours. acetone,
After sequentially washing with ethanol and pure water, it is immersed in a 2% glutaraldehyde (manufactured by Polyscience Co., Ltd.) solution for 2 hours at room temperature. After washing with pure water, it is immersed in physiological saline containing 1000 U/ml of urokinase (Midori Juji Co., Ltd.) at 4°C for 24 hours. It was washed with physiological saline and pure water to obtain a urokinase-immobilized film (). As a comparative example, a film (2) was prepared in which the film (2) was not treated with a silane coupling agent but was treated with glutaraldehyde and urokinase. Urokinase activity was measured by fibrin plate method. The fibrin plate was prepared according to the 29th revised edition of "Clinical Test Method Summary" edited by Masamitsu Kanai (June 1982) published by Kanehara Publishing, and the dissolution area of the fibrin plate after incubation at 37°C for 18 hours was calculated as the activity of urokinase. Quantity. The evaluation film had a circular size of 38 mm ² . The measurement results are shown in Table 2, and it can be seen that the urokinase-immobilized film () according to the present invention maintains its activity even after repeated measurements.

[Table] Example 3 A hydrophilic material made by grafting polyethylene glycol (degree of polymerization 6000) onto chlorosulfonated polyethylene using a vinyl chloride resin tube with an inner diameter of 3 mmφ and an outer diameter of 4 mmφ (grafting rate 10%, Sanyo Chemical Co., Ltd.)
After immersing the tube in a 5% THF solution (manufactured by Kawasaki Co., Ltd.) for 5 seconds, the tube was vacuum dried to produce a tube made of vinyl chloride resin whose inner and outer surfaces were coated with a hydrophilic material. This tube was treated with a silane coupling agent, glutaraldehyde, and urokinase in the same manner as in Example 2 to obtain a urokinase-immobilized tube. A bypass was formed in the dog's jugular vein using this urokinase-immobilized tube, and an antithrombotic test was conducted. When the tube was removed after 12 hours and the presence of thrombus on the inner surface was observed, no thrombus had been formed at all. On the other hand, when a tube made of vinyl chloride resin without urokinase immobilized was used as a comparative example, the tube was completely occluded in about 1 hour.

Claims (1)

[Claims] 1. An antithrombotic agent characterized in that a physiologically active substance is immobilized on a hydrophilic material obtained by grafting polyethylene glycol onto a polymer substance via a silane coupling agent having an amino group. sexual material. 2. The antithrombotic material according to claim 1, wherein the polymeric substance is a chlorosulfonated polymer. 3. The antithrombotic material according to claim 1, wherein the physiologically active substance is urokinase, streptokinase, heparin, or TPA.