JP2006198393A - Medical equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a medical equipment which has antithrombogenicity, biocompatibility, and intensity in itself, and uses a composite material with the antithrombogenicity excellent in handleability. <P>SOLUTION: A medical equipment concerning this invention is characterized in that a part or all of a section that blood contacts is formed or covered by a composite material with antithrombogenicity where carbon nanotube is mixed into matrix resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a medical device, and more particularly to a medical device using an antithrombotic material.

  It is an unavoidable phenomenon that a thrombus is formed on the surface of a medical device used inside or outside a living body such as a catheter. The mechanism of thrombus growth is very complex, and all blood components are involved in thrombus formation on the surface of biological material. In order to solve this problem, one researcher is trying to elucidate the mechanism of thrombus formation, and another researcher is working on the development of a new material that suppresses thrombus formation as a medical device material.

As these new materials, Japanese Patent Laid-Open No. 2001-29447 (Patent Document 1) discloses a technique for coating the surface of a medical device with a special fluorine-containing diamond-like carbon film.
Japanese Patent Application Laid-Open No. 11-502734 (Patent Document 2) discloses a technique for coating the surface of a medical device with a hydrophilic polymer containing an antithrombotic agent.
Japanese Patent Application Publication No. 2004-512397 (Patent Document 3) discloses a technique for coating the surface of a medical device with a hydrophobic multiple composite heparin conjugate.
Japanese Patent Application Laid-Open No. 7-16292 (Patent Document 4) discloses a special antithrombotic material for medical devices made of a graft copolymer.
Further, JP-A-6-277293 (Patent Document 5) discloses a composition comprising a polyether block amide copolymer, polyurethane and an X-ray contrast agent.
JP 2001-29447 A Japanese National Patent Publication No. 11-502734 Special table 2004-512397 JP 7-16292 A JP-A-6-277293

By the way, the above-mentioned new material having antithrombogenicity uses a special material, and the manufacturing method is complicated, becomes expensive, and is not necessarily excellent in handleability.
The present invention provides a medical device using a composite material having antithrombogenicity that has antithrombogenicity and biocompatibility, has strength itself, and is excellent in handleability.

The medical device according to the present invention is characterized in that a part or all of a portion that comes into contact with blood is formed or coated with a composite material having antithrombotic properties in which carbon nanotubes are mixed in a matrix resin.
As the composite material, a matrix resin in which 1 wt% to 30 wt% of carbon nanotubes are mixed can be used.
The carbon nanotube is preferably a graphitized carbon nanotube.
As the carbon nanotube, a carbon nanotube obtained by a vapor phase growth method in which a hydrocarbon gas is subjected to vapor phase pyrolysis in the presence of an iron-based catalyst can be used.
The iron content of the carbon nanotube is preferably 500 ppm or less.
The medical device according to the present invention is suitable for devices that are implanted in the body, such as artificial organs, drug transport pipes, and stents.
The medical device according to the present invention is also suitable for devices used in vitro, such as blood test related devices and surgery related devices.

  In the composite material in which carbon nanotubes (CNT) are mixed in the matrix resin, the surface of the matrix resin is densified and smoothed because the CNT forms the crystallization nucleus of the matrix resin and promotes the crystallization of the matrix resin. Because of this, it is considered that the reactivity with blood is lowered and good antithrombotic properties are exhibited. Therefore, a medical device using this composite material at a site in contact with blood has excellent antithrombogenicity. In addition, the CNT mixed in increases the strength and flexibility, and improves the operability and handling of the medical device. In addition, since it has biocompatibility, in a medical device that is implanted in the body for a long term or semipermanently, there is little adverse effect on the tissue at the site of implantation and contact.

The best mode of the present invention will be described in detail below.
First, the composite material used for the medical device of the present invention will be described.
This composite material is a matrix resin in which carbon nanotubes are mixed, and has antithrombogenicity under an environmental condition in contact with blood. In addition, the composite material has low foreign substance rejection reactivity when embedded in a living body and is excellent in biocompatibility. Therefore, this composite material can be suitably used as an antithrombotic medical device material, in particular, as a medical device material embedded in a living body.
Examples of matrix resin materials include polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyester elastomers using these as hard segments, polyolefins and polyolefin elastomers such as polyethylene and polypropylene, copolymer polyolefins using a metallocene catalyst, Vinyl polymers such as vinyl chloride, PVDC, PVDF, polyamide and polyamide elastomer (PAE) including nylon, polyimide, polystyrene, SEBS resin, polyurethane, polyurethane elastomer, ABS resin, acrylic resin, polyarylate, polycarbonate, polyoxymethylene ( POM), polyvinyl alcohol (PVA), fluororesin (ETFE, PFA, PTFE), Tylene-vinyl acetate saponified product, ethylene-copoly-vinyl alcohol, ethylene vinyl acetate, carboxymethylcellulose, methylcellulose, cellulose acetate, vinylpolysulfone, liquid crystal polymer (LCP), polyethersulfone (PES), polyetheretherketone (PEEK) In addition to various thermoplastic resins such as polyphenylene oxide (PPO) and polyphenylene sulfide (PPS) and their polymer derivatives, thermosetting or crosslinkable resins such as vulcanized rubber, silicone resin, epoxy resin, two-component reactive polyurethane resin, etc. Is mentioned.
Examples of the nylon include nylon 6, nylon 64, nylon 66, nylon 610, nylon 612, nylon 46, nylon 9, nylon 11, nylon 12, and the like. Nylon 12 is particularly preferable.

The carbon nanotube (CNT) used in the present invention is preferably produced by a vapor phase growth method in which a gas such as hydrocarbon is vapor-phase pyrolyzed in the presence of a metal catalyst.
For example, organic compounds such as benzene and toluene are used as raw materials, organic transition metal compounds such as ferrocene and nickelcene are used as metal catalysts, and these are introduced into a high-temperature reactor together with a carrier gas to generate CNTs on a substrate. Use a method (Japanese Patent Laid-Open No. 60-27700), a method of generating CNTs in a floating state (Japanese Patent Laid-Open No. 60-54998), or a method of growing CNTs on the reactor wall (Japanese Patent No. 2778434). Can do. In addition, as disclosed in Japanese Patent Publication No. 3-64606, metal-containing particles previously supported on a refractory support such as alumina and carbon are brought into contact with a carbon-containing compound at a high temperature to obtain CNTs having a diameter of 70 nm or less. You can also get it.

The thickness (diameter) of the CNT used is 1 nm to 350 nm, preferably 10 nm to 300 nm or 50 nm to 200 nm, and particularly preferably 70 nm to 160 nm.
If the CNT has a thickness smaller than 1 nm, the dispersibility with respect to the matrix resin is not good, which is not preferable. On the other hand, if it is thicker than 350 nm, it may protrude from the surface of the matrix resin, or unevenness may occur and the flatness of the material may be impaired, and a thin material (pipe shape, sheet shape, etc.) can be obtained. It is not preferable.
The aspect ratio of CNT is preferably about 50 to 200.

The CNT produced by the vapor phase growth method is heat-treated at a high temperature and graphitized. The heat treatment temperature is 2000 ° C. or higher, preferably 2500 ° C. or higher, and particularly preferably 2800 ° C. to 3200 ° C. When the processing temperature of CNT is 2000 ° C. or less, there are amorphous deposits deposited on the surface of the CNT during vapor phase growth, and impurities such as remaining catalytic metals, and as medical device materials, It is not preferable. By performing heat treatment at 2000 ° C. or higher, impurities such as amorphous deposits deposited on the CNT surface and remaining catalytic metals are removed and cleaned, so that they can be suitably used as materials for medical devices. it can. Heat treatment at 2500 ° C or higher graphitizes (crystallizes) the CNT skeleton, improves conductivity, and improves thermal conductivity, making it suitable for applications that require electrical conductivity and thermal conductivity It becomes possible to cope with.
Moreover, suppleness (flexibility) comes out by graphitizing. When the CNTs are so flexible, they are mixed into the matrix resin and manufactured into a tube-like medical device (for example, a catheter or a blood distribution / transfer pipe for blood test). Of course, when the tube is broken, it is easily restored and the operability (handling) is good.
Conversely, if the heat treatment temperature is 3200 ° C. or higher, the graphite is sublimated, the graphite skeleton is destroyed, and the strength is lowered, which is not preferable.
Further, the iron (Fe) contained in the CNT is set to 500 ppm or less, preferably 150 ppm or less, and particularly preferably 100 ppm or less. If Fe is present in an amount of 500 ppm or more, there is a concern about adverse effects on the human body, which is not preferable as a medical device material.

The blending ratio of CNT to the matrix resin is preferably in the range of 1 wt% to 30 wt%, preferably 5 wt% to 20 wt%, more preferably 7 wt% to 15 wt%.
When the CNT content is less than 1 wt%, good antithrombotic properties are not exhibited. In addition, when the CNT content is more than 30 wt%, the mixing with the matrix resin cannot be performed well, the material becomes tattered and cannot be molded, and the strength is not obtained. Moreover, since CNT is expensive, it becomes expensive and is not preferable.
Examples of a method for uniformly dispersing CNT in the matrix resin include known methods such as using a screw kneader. In order to improve dispersibility, ultrasonic vibration may be applied to the mixture of CNT and matrix resin for a certain period of time. In order to improve the adhesion between the two, the surface structure of the CNT can be modified with, for example, a silane coupling agent.

In the above composite material, carbon nanotubes (CNT) form nuclei of crystallization of the matrix resin and promote crystallization by blending CNT into the matrix resin, so that the surface of the matrix resin becomes dense and smooth. This is thought to reduce the reactivity with blood and thus exhibit good antithrombogenicity. In addition, the composite material has low foreign substance rejection reactivity when embedded in a living body and is excellent in biocompatibility.
The medical device according to the present invention is characterized in that a part or all of a portion of the medical device that comes into contact with blood is formed or covered with the above composite material having antithrombotic properties in which carbon nanotubes are mixed in a matrix resin. It is said.

In the present invention, as described above, part or all of the part of the medical device that comes into contact with blood is formed of the composite material.
FIG. 1 is a cross-sectional view showing an example of various medical tubes 10, and the entire tube 10 is formed of the composite material 12. The tube 10 can be manufactured by extrusion molding.
FIG. 2 is a cross-sectional view showing an example of a medical tube 20 having a two-layer structure, in which blood comes into contact, for example, the inner layer 12 is formed of the composite material, and the outer layer 14 is mixed with another, for example, CNT. Not formed with nylon resin. Of course, if the side in contact with blood is the outer layer 14, the outer layer 14 side is formed of the composite material. The two-layer tube 20 can also be easily formed by extrusion.

As a manufacturing method of the medical device or its parts, in addition to the extrusion molding method, a normal molding method, for example, an injection molding method using the composite material can be adopted.
Alternatively, a base member is prepared by injection or the like using another material, and the composite material is applied onto the base member to form a composite material layer on the surface of the base member that contacts blood. It is good (not shown). For example, in the case of a resin containing CNT, such as a medical stent, a pump, and a pacemaker, which cannot be manufactured for reasons such as strength and structure, a portion that comes into contact with blood or a human body can be coated and coated with the composite material.

The coating method can be obtained by immersing or applying a stent or the like in a paint obtained by mixing CNT, a resin component, and a solvent added as necessary, and drying. Examples of the resin component include thermoplastic resins such as polyethylene, polypropylene, polyamide, polyacrylate, polyvinyl chloride, polyacrylonitrile, polycarbonate, fluorine resin, and butadiene resin. Moreover, you may add one or more types of thermosetting resins, such as a phenol resin, unsaturated polyester resin, and an epoxy resin. Solvents include alcohols such as methanol and ethanol, ester solvents such as methyl acetate, ethyl acetate and amyl acetate, ketone solvents such as acetone and methyl acetone, ether solvents such as methyl ether and glycol methyl ether, kerosene, One or more hydrocarbon solvents such as benzol and xylol can be used. As a mixing method, a mixer, a kneader, or a known mixer can be used. The order of mixing the components is not particularly limited.

Examples of the medical device of the present invention include the following.
That is, surgical sheets that come into contact with blood, scalpels, pipettes, medical / physiological cloths, cloths, blood collection needles for blood tests, blood collection and storage bottles, blood transfer pipes, blood test equipment, pipettes, etc. Various catheters (jugular nutrition catheters, intravascular catheters, vasodilator catheters, contrast catheters, etc.), endoscope tubes, introducer sheaths, hemodialysis tubes, cardiopulmonary bypass, as well as in vitro applications There are a wide range of uses in vivo such as tubes, various tubes such as blood distribution / transfer pipes, left ventricular assist devices and vasodilators.
In particular, because it has biocompatibility, not only artificial organs (artificial blood vessels, artificial joints, etc.), but also medical devices (for example, pacemakers, micropumps, drug transport pipes, etc.) that are retained (embedded) in the human body for a long period of time It is effective in. Furthermore, as described above, the parts that come into contact with blood or the human body, such as stents, pumps, pacemakers, etc., that cannot be manufactured due to strength, structure, etc., with existing resin materials, etc. are mixed with the above CNT. Since it can be coated and coated with a composite material, it can be applied to a wider range of medical devices. In addition, due to the conductivity and thermal conductivity of CNT, it can be applied to a wider range of medical devices.
Since the structures of these medical devices themselves may be known, a description of the structure is omitted.
The “equipment” of the medical device in the present invention is a concept that includes all medical devices such as medical devices, their components, or medical instruments and materials as described above. Used.

A. Antithrombogenicity test CNTs were produced as follows.
Attach a spray nozzle to the top of a vertical heating furnace (inner diameter 17.0cm, length 150cm). The temperature of the inner wall of the heating furnace is raised and maintained at 1200 ° C., and 20 g / min of a liquid raw material of benzene containing 4 wt% ferrocene is sprayed directly from the spray nozzle onto the furnace wall at a hydrogen gas flow rate of 100 l / min ( Spray) Supply to spray. The shape of the spray at this time is a conical side surface (trumpet shape or umbrella shape), and the apex angle θ of the nozzle is 60 °. Under such conditions, ferrocene was pyrolyzed to produce iron fine particles, which became seeds, and produced and grown carbon fibers from carbon by pyrolysis of benzene. The vapor grown carbon fiber grown by this method was continuously produced for 1 hour while scraping off at intervals of 5 minutes.
The obtained carbon fiber was heat-treated at a temperature of 2800 ° C. for 30 minutes in an argon atmosphere.
A high-purity multiwall CNT (MWNT) having a diameter of about 80 nm, a length of 10 μm to 20 μm, a specific surface area (BET method) of 18 m ² / g, and a true specific gravity of 2.08 g / cm ³ was obtained. It is relatively straight and shows a long tubular shape. Metal impurities were 100 ppm or less (iron was 30 ppm or less) (measured by atomic absorption method).

2. Thrombus formation test 10 wt% of carbon nanotubes (CNT) obtained as described above were mixed with nylon 12 as a matrix resin. This mixing was performed with a conventional mixer. Next, this mixture was extruded into a tube shape with a normal twin-screw extruder to form a microcatheter (new catheter) having an inner diameter of 0.46 mm and an outer diameter of 0.53 mm.

Using the above-mentioned new catheter and a control catheter made only of nylon, a thrombus formation test was performed in an environment inside and outside the living body.
Beagle dogs (adult dogs) weighing 9-11 kg were subjected to a thrombus formation test. An anesthetic was injected into the dog's vein, the tube was inserted into the trachea, and ventilated with room air by a respirator. The ventilation rate was (12-15) times / minute, the air volume was (15-20) ml / kg, and the arterial blood pH and O ₂ partial pressure were adjusted to be maintained within the physiological range. Body temperature was maintained at 36 ° C. using a heating lamp.
A common vinyl tube was set via the brachial artery into the subclavian artery and connected to a pressure transducer to systematically measure blood pressure. LeadII ECG was monitored with a bioamplifier.
In addition, a vinyl tube was set in the subclavian vein via the brachial vein to inject the lactated Ringer solution into the vein when necessary. Approximately 5 cm on both sides of the femur and the normal carotid artery were surgically exposed. These arteries were taped to avoid bleeding while being replaced with each catheter to be tested. The test catheter was inserted into the artery at an angle of about 45 ° from the center to the peripheral portion. Thus, the tip of the catheter was placed at the center of the artery lumen. The end of the test catheter was then placed in the adventitia of the seam to avoid bleeding after the tape closure was released. The artery was removed 1 hour after restarting blood flow with the indwelling test catheter. The removed artery was fixed in 70 wt% alcohol and embedded with paraffin. Thin sections of each sample were stained with hematoxylin and eosin.

As an example of an in vitro environment, in order to evaluate blood clotting in a test tube, a new 0.8 cm test catheter was fixed by passing a thin surgical nylon thread through the inner lumen of the catheter. Venous blood of a 5 ml dog without anticoagulant was sampled. Immediately after sampling, the blood was transferred to a dish and the tube was placed in the blood for 1 hour. Evaluation of the blood mass on the catheter was performed by gently lifting the thread. To observe with SEM, the tube was immersed in a chilled 2% glutaraldehyde solution under phosphate buffer. Each sample was then dehydrated with graded ethanol and dried over CO ₂ by the critical point method. The dry surface was mounted and sputter coated with gold, palladium and carbon. The sample was sputter coated with gold / palladium at 50 nm, and observed with a scanning electron microscope under JEOL-JSM6000 at 15 kev.

3. Results and Discussion FIGS. 3C and 3D show a cross section of a catheter (new catheter) made of a nylon-CNT (MWNT) composite material. A relatively uniform CNT dispersion can be confirmed by FE-SEM (FIG. 3D). Furthermore, CNT is not found on the inner and outer wall surfaces and does not protrude on the inner and outer wall surfaces. 3A and 3B show a cross section of a control catheter made of only nylon.
The elastic modulus of the new CNT-based catheter is about 1.5 times that of the nylon-based control catheter (1200 MPa versus 820 MPa). As described above, the new CNT-based catheter is excellent in strength and can be restored immediately even if it is broken once, so that operability (handling) is improved.
FIG. 4 shows a section of the removed artery. FIG. 4A shows an artery when a control catheter is used, and FIG. 4B shows an artery when a new catheter is used. The artery is colored with hematoxylin and eosin. In the upper continuous section (FIG. 4 (a)), darker areas in the internal arterial space indicate prominent thrombus. The location where the control catheter was inserted is shown as an opaque hole in Section 3-5 (the leftmost figure is Section 1), indicating that the inserted catheter has been displaced diagonally from the adventitia to the center of the artery. Yes.
In this control catheter, it is speculated that thrombus formation was promoted by rheological changes in blood flow (for example, laminar turbulence, vortex flow, irregular movement, etc.).

  On the other hand, in the case of the new catheter, as shown in the lower cross section (FIG. 4B), the thrombus can be seen only in section 3 (third figure from the left, located at the insertion position of the catheter). From these observations it is clear that the new catheter is less reactive with blood if the blood flow is not disturbed. That is, thrombus formation in an artery in vivo is greatly suppressed with this new catheter.

  Blood clot formation was examined by lifting the catheter from the dish. As shown in FIG. 5 (a), blood coagulation around the control catheter is significant. However, as shown in FIG. 5B, the new catheter has a very low blood response. SEM observation for detailed morphology observation of coagulation formation was performed on both samples (FIG. 6). 6A shows the control catheter, and FIG. 6B shows the new catheter. Both catheters have fibril-like networks and blood cells, but the size of the fibrils and blood cells are relatively small for the new catheter.

  SEM observation of the inner tube surface of the catheter shows that the inner tube surface of the new catheter is smoother than that of the control catheter (FIG. 7). FIG. 7A shows the control catheter, and FIG. 7B shows the new catheter. From these experimental results, the following can be said. That is, a catheter using CNT as a functional filler suppresses blood reactions such as coagulation and fibril deposition.

4). Conclusion The above experiments have shown that the new catheter made of CNT and nylon 12 improves the mechanical properties, reduces blood clotting, etc. and is very promising for medical applications.
Furthermore, the increase in mechanical strength inherent to CNTs leads to an improvement in operability such as breaking strength during operation and easy restoration even if the new catheter is bent by an obstacle.
Moreover, it has a smooth (smooth) inner surface of the tube, and that the CNT is not exposed on the outer surface of the new catheter indicates that the possibility of a direct reaction between CNT and blood is reduced. It is considered that CNT has a nucleation function of crystallization of matrix resin (nylon), thereby forming a dense and smooth surface form, which is considered to be one cause of reducing thrombus formation. The improved electrostatic properties of CNTs are also considered to be a factor that reduces thrombus formation. That is, it is considered that surface charging is related to thrombus formation, and the new catheter has higher electrical conductivity than the control catheter. Therefore, it is presumed that the new catheter has no charging property, is hardly charged, and has excellent antithrombotic properties.

B. Biocompatibility Furthermore, we examined the biocompatibility of the new catheter.
1. Experimental animals, transplantation method and specimen collection Ten female BALB / c mice (5 weeks old) were purchased from SLC (Japan). These mice were raised in a sterile facility at Shinshu University School of Medicine. The experiment started when the mice were 6 weeks old. These animals were divided into two groups: a control catheter graft group and a new catheter graft group. These grouped animals obtained blood and skin tissue samples from the heart one week after transplantation. The animal was incised through the skin of the back 1 cm under furosene anesthesia. All catheters were disinfected by exposure to formaldehyde gas for more than 24 hours at room temperature. These catheters were cut and implanted into the subcutaneous tissue to the length tested here (approximately 0.5 mm; the control and new catheters were 2.3 mg and 1.92 mg, respectively). The incised wound was sewn together. One week after transplantation into the tissue, the animals were dissected under deep anesthesia using furocene. For flow cytometry measurements, a needle was inserted into the heart and blood was sampled, and skin tissue including the muscle layer was excised for pathological examination.
2. Test 2-1. Flow cytometry The collected blood is colored with CD4 ⁺ and CD8 ⁺ antibodies (BD Biosciences Farmingen USA) to sort T lymphocytes by flow cytometer (FACS Cribber, Becton Dickinson USA). It was. These colored cells were analyzed using Cell Quest software (Becton Dickinson). Data were expressed as mean + SE. The difference between the two was evaluated by a statistical method (risk rate of 5% or less).
(1) One week after transplantation of the control catheter group, CD4 ⁺ T cells were 51.5 ± 2.7%, and the new catheter group was at the same level (49.7 ± 2.0%) ( FIG. 8 (a)).
(2) The value of CD8 ⁺ T cells in the control catheter (1 week after transplantation) is 14.3 ± 0.8%, and the corresponding value of the new catheter is 16.3 ± 0.9%, which is significantly higher ( FIG. 8B).
(3) Further, the ratio (calculated value) between CD4 ⁺ and CD8 ⁺ was 3.72 ± 0.25 for the control catheter, while the value for the new catheter group was significantly 3.07 ± 0.1. Low (FIG. 8 (c)).
From the above (1), (2) and (3), the MHC class 1 pathway in the antigen-antibody reaction system is enhanced in the control catheter group. That is, it can be said that the new catheter is less responsive to the foreign body rejection reaction than the control catheter.
CD4 is a label on the surface of helper T lymphocytes that regulate all aspects of immune function, and CD4 lymphocytes have the effect of promoting the action of making antibodies against antigens. CD8 is a label on the surface of cypressor T lymphocytes, and CD8 lymphocytes serve as a brake that suppresses excessive production of antibodies. Furthermore, the ratio of CD4 to CD8 (CD4 / CD8) is important for viewing immune function, and this ratio decreases as immune function deteriorates. That is, the foreign substance reactivity is reduced.
2-2. Tissue structure As a convenient tissue structure, the tissue was taken immediately after dissection, fixed in 10% formaldehyde, embedded in paraffin, cut into 5 micron sections, and stained with hematoxylin and eosin.
The state of macroscopic observation of the transplanted embedded tissue is shown in FIG. In the control catheter (FIG. 9 (a)), the implanted piece is confined by new vessels and an inflamed thick membrane. However, this has not happened with the new catheter (FIG. 9 (b)). Furthermore, the histology and pathological appearance of the transplanted microcatheter after the lapse of one week are shown in FIG. Granulation tissue with cell infiltration clearly appears in the control catheter group (FIG. 10 (a)). Compared with the new catheter group, it is shown that the formation of granulation tissue enveloping the control catheter piece has occurred remarkably (FIG. 10 (b)).
3. Conclusion As described above, it has been confirmed that a new catheter made of a composite material of CNT and nylon has biological properties excellent in antithrombogenicity and biocompatibility.

It is explanatory drawing of the medical tube formed in the single layer structure. It is explanatory drawing of the medical tube formed in the 2 layer structure. 3A and 3B are cross-sectional photographs of the control catheter. 3 (c) and (d) are cross-sectional photographs of the CNT-nylon composite material. FIG. 4A is a cross-sectional photograph of an artery into which a control catheter has been inserted. FIG. 4B is a cross-sectional photograph of the artery into which the CNT-nylon composite material has been inserted. FIG. 5 (a) is a photograph showing the blood coagulation state around the control catheter. FIG. 5B is a photograph showing the blood coagulation state around the new catheter. FIG. 6A is an SEM photograph showing the blood coagulation state in the case of the control catheter. FIG. 6B is a SEM photograph showing the blood coagulation state in the case of the new catheter. FIG. 7A is an SEM photograph of the inner surface of the control catheter. FIG. 7B is a SEM photograph of the inner surface of the new catheter. CD4 ⁺ after each microcatheter subcutaneous implantation is a graph showing the CD8 ⁺ and CD4 ⁺ / CD8 ⁺ change in. The asterisk has a risk rate of 5% or less, indicating that the new catheter is statistically significant different from the control catheter. It is a macroscopic observation (FIG. 9 (a): control catheter, FIG.9 (b): new catheter) of the skin tissue which embedded the microcatheter. Fig. 10 (a): Optical micrograph of skin tissue embedded with control catheter, Fig. 10 (b): Optical micrograph of skin tissue embedded with new catheter, with different magnifications from top to bottom. Yes.

Explanation of symbols

10 tube 12 inner layer 14 outer layer 20 tube

Claims (7)

  A medical device characterized in that a part or all of a site in contact with blood is formed or coated with a composite material having antithrombogenic properties in which carbon nanotubes are mixed in a matrix resin.   The medical device according to claim 1, wherein the composite material is a matrix resin in which 1 wt% to 30 wt% of carbon nanotubes are mixed.   The medical device according to claim 1 or 2, wherein the carbon nanotube is a graphitized carbon nanotube.   The medical device according to any one of claims 1 to 3, wherein the carbon nanotube is a carbon nanotube obtained by a vapor phase growth method in which a hydrocarbon gas is thermally decomposed in the presence of an iron-based catalyst. machine.   The medical device according to claim 4, wherein the carbon nanotube has an iron content of 500 ppm or less.   The medical device according to any one of claims 1 to 5, wherein the medical device is used by being embedded in a body such as an artificial organ, a drug transport pipe, or a stent.   The medical device according to any one of claims 1 to 5, wherein the medical device is used outside a living body such as a blood test related device or a surgery related device.