CA1117696A - Process for producing biocompatible materials of a polyamide type and articles obtained thereby - Google Patents
Process for producing biocompatible materials of a polyamide type and articles obtained therebyInfo
- Publication number
- CA1117696A CA1117696A CA000325378A CA325378A CA1117696A CA 1117696 A CA1117696 A CA 1117696A CA 000325378 A CA000325378 A CA 000325378A CA 325378 A CA325378 A CA 325378A CA 1117696 A CA1117696 A CA 1117696A
- Authority
- CA
- Canada
- Prior art keywords
- polyamide
- nylon
- temperature
- materials
- reaction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
- C08J7/12—Chemical modification
- C08J7/14—Chemical modification with acids, their salts or anhydrides
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L33/00—Antithrombogenic treatment of surgical articles, e.g. sutures, catheters, prostheses, or of articles for the manipulation or conditioning of blood; Materials for such treatment
- A61L33/0076—Chemical modification of the substrate
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
- C08G69/48—Polymers modified by chemical after-treatment
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2377/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S128/00—Surgery
- Y10S128/03—Heart-lung
Abstract
ABSTRACT OF THE DISCLOSURE
Polyamide materials for the constructionof pro-theses and surgical sundries are made biocompatible by inducing a superficial hydrolysis by treating such mate-rials, either raw or in the form of shaped articles, with a normal multiple solution of hydrogen chloride.
Thrice normal or fourfold normal solutions are prefer-red and the treatment time being a function of the temperature. At human body temperature (37°C) a teat-ment time from 30 to 60 minutes will do.
Polyamide materials for the constructionof pro-theses and surgical sundries are made biocompatible by inducing a superficial hydrolysis by treating such mate-rials, either raw or in the form of shaped articles, with a normal multiple solution of hydrogen chloride.
Thrice normal or fourfold normal solutions are prefer-red and the treatment time being a function of the temperature. At human body temperature (37°C) a teat-ment time from 30 to 60 minutes will do.
Description
~11769~
PROCESS FOR PRODUCING BIOCOMPATIBLE MATERIALS
OF A POLYAMIDE TYPE ~ND ARTICLES OBTIANED TEIEREBY.
This invention relates to a process for the pre-paration of biocompatible materials of a polyamide type;
it relates, in addition, to the products thus obtained.
The use of polymeric materials in the biomedical art has become more and more widespread in the last years.
One of the major hindrances against an ever wider use of such materials is their usually poor compatibility with blood. For this reason, materials which have now attained appreciable mechanical properties and which would be extremely useful in artificial protheses, do not find, in the actual practice, an application on account of their high tendency towards the formation of thrombi. Nylon is an example, which, on account of its mechanical properties, would find a wide application in the field referred to above, should it not be extremely prone to the formation of thrombi.
The problem of the thrombogenic nature of the polymeric materials has invited many searchers to try and find out the origins. More particularly, the properties of the surfaces have been studied in order to find out a possible correlation between them and the materials in question when placed in contact with blood.
A few authors have tried to correlate the thrombo-genic nature of the polymeric materials with the surface tension or the Z potential. See, for example, the articles by S. D. Bruck in Biomat., Med. Dev. Art. Org. 1, 191, 1973 and in J. Biomed. Mat. Res. Symposium N8 page 1 (1977), from which it would appear that the biocompatibility of a - 30 few materials such as polyurethans may be correlated with a negative Z-potential measured in vitro using the Krebs solution, and with a critical surface tension below 30 dynes/cm.
,~ ~
It is generally believed that a material having a negatlve surface charge has good chances of being biocompatible, on account of the fact the blood platelets have a negative surface charge.
Another parameter which is ganerally accepted in evaluating the materials is the capacity of selectively absorblng a few proteins on the surface when placed in contact with blood.
- In this connection, see the artlcle by D. J. Slmon, in Trans. Amer. Soc. Art. Int. Organs, XXI, 49, 1975 wherein the lack of adhesion of the platelets to several materials such as polyurethans, silastic resins and Teflon (Reg. Trade Mark) is correlated with the preferential adsorption of albumin as compared with globulins and fibrinogen.
It is likewise known that polyamide substrates can be hydrolized in order to set free completely the amine and carboxyl groups, but it has proven extremely difficult to carry out s~ch a hydrolysis in such a way as to ohtain a final product which is only partially modified.
It is thus extremely surprising that the present - 20 applicants have succeeded in carrying out a unique super-ficial h~drolysis of the starti~g m~te~ials.~n.d co~curxentl~
obtaining biocompatible materi.als ~hich can be employed for the purposes indicated abo~e ~ithout suffering of any of the shortcomings aforementioned.
As a matter of fact, the object of the present invention is to provide a process fo~ the superficial hydrolysis of polyamide materials, which permits to obtain materials which are only partially modified and exhibit a high degree . of biocompatibility.
Such a reaction is carried out by carefully check-ing the hydrolizing agent and the reaction conditio~s. More - particularly, hydrochloric acid is used as a concentration of from 3 to 4-normal and the temperature may be mainta.ined .- in the interval from 20C to 40C.
The reaction time~ in its turn., is selected as a function of the working temperature: thus one passes fro~
10 to 30 hours at a temperature of 25C to 30 to 60 minutes at a temperature of 37C. There is, in practice, an inverse relationship between the temperature within the range considered above and the reaction time~ these two p~rameters m.ust be accurately coordinated in order that the desired ~alues may be obtained, inasmuch as lower ~alues of the tPmperature require longer reaction times.
As regards the starting materials, it is possible to start from any king of material of a polyamide nature:
poly-caprolactam and the various types of aliphatic or aromatic nylons are especially advisable. The treatment consists, in practice, in introducing on the surface of such materials, an lnfinity of dipoles the overall charge of which is zero.
Inasmuch as the procedure which renders the articles made with these materials biocompatible is a hland superficial hydrolysis, it can be surmised that any chemical modification undergone by biocompatible articles of this kind (provided that ; it is a nondestructive modification, of course) will not impair the hcaracteristics of biocompatibility of the material concerned.
It is possible to select, from among the wide host of existing polyamides, materials which lend themselves to different uses. It becomes thus possible to exploit articles which range from those adapted from lonlasting protheses to thin membranes which are gas-pervious and can be used for heart-lung machines and for artificial kidneys.
The articles can be made starting ~rom an already modified polyamide, or the modification can be carried out on an already shaped article. In addition, the polyamide can be admixed with one or more conventional ingredients.
The invention is described in detail with the aid of the following examples which are not to be construed as limitations.
~XAMPLE
5 metres of Nylon-6 thread (dia. 0.25 mm, commercial polycaprolactam) have been twise extracted with dioxan and petroleum ether (40/60 by vol), under reflux conditions for two hours. The thread has been subsequently washed, first with acetone and then with water, whereafter it has been subjected to a superficial hydrolysis with ~Cl (3 time normal = 3N) at 37C. The hydrolysis last 30 minutes, where-after the thread has been washed with 0.1 N NaOH and then with water.
The completion of the hydrolysis and thus the presence of amine groups on the surface of the thread has been confirmed by colorimetric assays. A sample of the thread has been immersed ln a 0.1% (wt/vol) solution of trinitrobenzene-sulfonic acid in saturated tetraborate and, after one hour, it took a yellow-reddish hue, whereas a reference sample which had not been hydrolized did not take any color. The hydrolized nylon thread thus obtained has been carefully and evenly wrapped around an intravenous Teflon (R.T.M.) catheter (Wallace, length 30 cm, I.D. 0.69 mm, O.D. 1.14 mm) so to cover the surface satisfactorily. A similar comparison catheter has been prepared by using a non-hydrolized nylon thread. The two catheters have been inserted in the femoral veins of a medium-size dog kept under general aneasthesia (Pentothan, R.T.M.);
free breathing. A collateral of the femoral vein has been isolated, and a probe has been introduced along the entire length of the collateral so that a predominant portion of the probe was floating in the iliac vein and in the inferior vena cava. The end of the probe has been tied to the collateral branch of the femoral vein and covered by the muscle bundles.
Eventually, the wound has been stitched. In the same way, the second probe has been introduced in the other femoral vein of the test animal. Both before and after the operation, heparin has been administered to the animal to prevent vascular thrombi due to the surgical wounds. The probes have been left in situ for 30 days without administering any further anti-coagulants: on completion of this period, the animal has been killed and the probes withdrawn. The probe having the hydrolized nylon thread wrapper has been found clean and clot-free. Also the vascular wall was found in good conditions. I'he reference probe with the untreated nylon thread wrapper, conversely, has been found coated by numerous thrombi.
3 metres of tube of Nylon-66 (O.D. 9 mm, I.D. 7 mm) ~J
have been subjected to superficial hydrolysis by having a 3%
solution of HCl flowing therethrough at 37C for about one - hour. On completion oE the reaction, the tube has been washed with decinormal (o.l N) NaOH and then with water. The completion of the hydrolysis has been confirmed by the colorimetrlc procedure described in the previous Example. Irhe test of platelet adhesiveness has been carried out on sections of hydrolized nylon tube and on sections of untreated nylon tubes. The method of A. J. Hellem ~Platelet adhesiveness in von Willebrand's disease". A study with a new modification of the glass bead filter method, Scand. J. Haemat, 7, 37~, 1970) has been followed by using native blood of a healthy individual, drawn and caused to flow through the tubes tested by means of a pump having a rate of delivery of 4 mls per minute. Platelet counts have been made both before and after the flow of the blood through the nylon tubes.
The counts have been made by collecting blood samples in an aqueous solution containing bipotassic EDTA
at the concentration of 6 milligrams per 10 millilitres.
The platelet count has been made with a phase contrast microscope according to the method of Brecher and Cronkite (Morphology and enumeration of human blood platelets, J. Appl.
Physiol. 3, 365, 1950).
In the case of hydrolized Nylon tubes, no significant decrease has been observed of the n~mber of platelets in solution. On ~he contrary, on the untreated Nylon tubes, the platelet adhesiveness was 56.5%.
Rings of Nylon -66 have been prepared (length 9 mm, `~
30 I.D.-7 mm, O.D. 8 mm) and special care has been taken in machlning the eclges, which have been beveled and rounded. A
certain number of such rings has been hydrolized with HCl ~ .
', 69~
(3.5 normal) at 37C, for one hour. Also in this case, the completeness of the hydrolysls has been confirmed by the trinitrobenzene sulfonate tests. The rings of superficially hydrolized Nylon and other comparison rings have been inserted in the inferior vena cava of dogs of medium size by a thoraco-tomy under general anaesthesia (Nembutal, R.T.M.). Special care has been taken when inserting the rings. Care has been taken that the rings did not contact the atrium wall and that the vein wall was not damaged too much when inserting the ring.
It has been observed that the reference rings, after two hours, already exhibited numerous clots stuck to the walls and in some cases, even the obstruction of the prothesis has been expe-rienced. The hydrolized nylon rings, conversely, have been withdrawn after two weeks, cleaned and only in few cases a few thrombi have been seen on the inner ring wall.
~.~ r
PROCESS FOR PRODUCING BIOCOMPATIBLE MATERIALS
OF A POLYAMIDE TYPE ~ND ARTICLES OBTIANED TEIEREBY.
This invention relates to a process for the pre-paration of biocompatible materials of a polyamide type;
it relates, in addition, to the products thus obtained.
The use of polymeric materials in the biomedical art has become more and more widespread in the last years.
One of the major hindrances against an ever wider use of such materials is their usually poor compatibility with blood. For this reason, materials which have now attained appreciable mechanical properties and which would be extremely useful in artificial protheses, do not find, in the actual practice, an application on account of their high tendency towards the formation of thrombi. Nylon is an example, which, on account of its mechanical properties, would find a wide application in the field referred to above, should it not be extremely prone to the formation of thrombi.
The problem of the thrombogenic nature of the polymeric materials has invited many searchers to try and find out the origins. More particularly, the properties of the surfaces have been studied in order to find out a possible correlation between them and the materials in question when placed in contact with blood.
A few authors have tried to correlate the thrombo-genic nature of the polymeric materials with the surface tension or the Z potential. See, for example, the articles by S. D. Bruck in Biomat., Med. Dev. Art. Org. 1, 191, 1973 and in J. Biomed. Mat. Res. Symposium N8 page 1 (1977), from which it would appear that the biocompatibility of a - 30 few materials such as polyurethans may be correlated with a negative Z-potential measured in vitro using the Krebs solution, and with a critical surface tension below 30 dynes/cm.
,~ ~
It is generally believed that a material having a negatlve surface charge has good chances of being biocompatible, on account of the fact the blood platelets have a negative surface charge.
Another parameter which is ganerally accepted in evaluating the materials is the capacity of selectively absorblng a few proteins on the surface when placed in contact with blood.
- In this connection, see the artlcle by D. J. Slmon, in Trans. Amer. Soc. Art. Int. Organs, XXI, 49, 1975 wherein the lack of adhesion of the platelets to several materials such as polyurethans, silastic resins and Teflon (Reg. Trade Mark) is correlated with the preferential adsorption of albumin as compared with globulins and fibrinogen.
It is likewise known that polyamide substrates can be hydrolized in order to set free completely the amine and carboxyl groups, but it has proven extremely difficult to carry out s~ch a hydrolysis in such a way as to ohtain a final product which is only partially modified.
It is thus extremely surprising that the present - 20 applicants have succeeded in carrying out a unique super-ficial h~drolysis of the starti~g m~te~ials.~n.d co~curxentl~
obtaining biocompatible materi.als ~hich can be employed for the purposes indicated abo~e ~ithout suffering of any of the shortcomings aforementioned.
As a matter of fact, the object of the present invention is to provide a process fo~ the superficial hydrolysis of polyamide materials, which permits to obtain materials which are only partially modified and exhibit a high degree . of biocompatibility.
Such a reaction is carried out by carefully check-ing the hydrolizing agent and the reaction conditio~s. More - particularly, hydrochloric acid is used as a concentration of from 3 to 4-normal and the temperature may be mainta.ined .- in the interval from 20C to 40C.
The reaction time~ in its turn., is selected as a function of the working temperature: thus one passes fro~
10 to 30 hours at a temperature of 25C to 30 to 60 minutes at a temperature of 37C. There is, in practice, an inverse relationship between the temperature within the range considered above and the reaction time~ these two p~rameters m.ust be accurately coordinated in order that the desired ~alues may be obtained, inasmuch as lower ~alues of the tPmperature require longer reaction times.
As regards the starting materials, it is possible to start from any king of material of a polyamide nature:
poly-caprolactam and the various types of aliphatic or aromatic nylons are especially advisable. The treatment consists, in practice, in introducing on the surface of such materials, an lnfinity of dipoles the overall charge of which is zero.
Inasmuch as the procedure which renders the articles made with these materials biocompatible is a hland superficial hydrolysis, it can be surmised that any chemical modification undergone by biocompatible articles of this kind (provided that ; it is a nondestructive modification, of course) will not impair the hcaracteristics of biocompatibility of the material concerned.
It is possible to select, from among the wide host of existing polyamides, materials which lend themselves to different uses. It becomes thus possible to exploit articles which range from those adapted from lonlasting protheses to thin membranes which are gas-pervious and can be used for heart-lung machines and for artificial kidneys.
The articles can be made starting ~rom an already modified polyamide, or the modification can be carried out on an already shaped article. In addition, the polyamide can be admixed with one or more conventional ingredients.
The invention is described in detail with the aid of the following examples which are not to be construed as limitations.
~XAMPLE
5 metres of Nylon-6 thread (dia. 0.25 mm, commercial polycaprolactam) have been twise extracted with dioxan and petroleum ether (40/60 by vol), under reflux conditions for two hours. The thread has been subsequently washed, first with acetone and then with water, whereafter it has been subjected to a superficial hydrolysis with ~Cl (3 time normal = 3N) at 37C. The hydrolysis last 30 minutes, where-after the thread has been washed with 0.1 N NaOH and then with water.
The completion of the hydrolysis and thus the presence of amine groups on the surface of the thread has been confirmed by colorimetric assays. A sample of the thread has been immersed ln a 0.1% (wt/vol) solution of trinitrobenzene-sulfonic acid in saturated tetraborate and, after one hour, it took a yellow-reddish hue, whereas a reference sample which had not been hydrolized did not take any color. The hydrolized nylon thread thus obtained has been carefully and evenly wrapped around an intravenous Teflon (R.T.M.) catheter (Wallace, length 30 cm, I.D. 0.69 mm, O.D. 1.14 mm) so to cover the surface satisfactorily. A similar comparison catheter has been prepared by using a non-hydrolized nylon thread. The two catheters have been inserted in the femoral veins of a medium-size dog kept under general aneasthesia (Pentothan, R.T.M.);
free breathing. A collateral of the femoral vein has been isolated, and a probe has been introduced along the entire length of the collateral so that a predominant portion of the probe was floating in the iliac vein and in the inferior vena cava. The end of the probe has been tied to the collateral branch of the femoral vein and covered by the muscle bundles.
Eventually, the wound has been stitched. In the same way, the second probe has been introduced in the other femoral vein of the test animal. Both before and after the operation, heparin has been administered to the animal to prevent vascular thrombi due to the surgical wounds. The probes have been left in situ for 30 days without administering any further anti-coagulants: on completion of this period, the animal has been killed and the probes withdrawn. The probe having the hydrolized nylon thread wrapper has been found clean and clot-free. Also the vascular wall was found in good conditions. I'he reference probe with the untreated nylon thread wrapper, conversely, has been found coated by numerous thrombi.
3 metres of tube of Nylon-66 (O.D. 9 mm, I.D. 7 mm) ~J
have been subjected to superficial hydrolysis by having a 3%
solution of HCl flowing therethrough at 37C for about one - hour. On completion oE the reaction, the tube has been washed with decinormal (o.l N) NaOH and then with water. The completion of the hydrolysis has been confirmed by the colorimetrlc procedure described in the previous Example. Irhe test of platelet adhesiveness has been carried out on sections of hydrolized nylon tube and on sections of untreated nylon tubes. The method of A. J. Hellem ~Platelet adhesiveness in von Willebrand's disease". A study with a new modification of the glass bead filter method, Scand. J. Haemat, 7, 37~, 1970) has been followed by using native blood of a healthy individual, drawn and caused to flow through the tubes tested by means of a pump having a rate of delivery of 4 mls per minute. Platelet counts have been made both before and after the flow of the blood through the nylon tubes.
The counts have been made by collecting blood samples in an aqueous solution containing bipotassic EDTA
at the concentration of 6 milligrams per 10 millilitres.
The platelet count has been made with a phase contrast microscope according to the method of Brecher and Cronkite (Morphology and enumeration of human blood platelets, J. Appl.
Physiol. 3, 365, 1950).
In the case of hydrolized Nylon tubes, no significant decrease has been observed of the n~mber of platelets in solution. On ~he contrary, on the untreated Nylon tubes, the platelet adhesiveness was 56.5%.
Rings of Nylon -66 have been prepared (length 9 mm, `~
30 I.D.-7 mm, O.D. 8 mm) and special care has been taken in machlning the eclges, which have been beveled and rounded. A
certain number of such rings has been hydrolized with HCl ~ .
', 69~
(3.5 normal) at 37C, for one hour. Also in this case, the completeness of the hydrolysls has been confirmed by the trinitrobenzene sulfonate tests. The rings of superficially hydrolized Nylon and other comparison rings have been inserted in the inferior vena cava of dogs of medium size by a thoraco-tomy under general anaesthesia (Nembutal, R.T.M.). Special care has been taken when inserting the rings. Care has been taken that the rings did not contact the atrium wall and that the vein wall was not damaged too much when inserting the ring.
It has been observed that the reference rings, after two hours, already exhibited numerous clots stuck to the walls and in some cases, even the obstruction of the prothesis has been expe-rienced. The hydrolized nylon rings, conversely, have been withdrawn after two weeks, cleaned and only in few cases a few thrombi have been seen on the inner ring wall.
~.~ r
Claims (9)
1. A process for the preparation of a biocompatible polyamide material, said process comprising subjecting a polyamide material to superficial hydrolysis by reacting said polyamide material with a 3 to 4 normal hydrogen chloride solution, neutralizing said polyamide material with a base, and washing said neutralized material with water.
2. The process of claim 1 wherein said base is sodium hydroxide.
3. The process of claim 1 characterized in that the reaction is conducted at a temperature of from 20°C to 40°C.
4. The process of claim 3 wherein the reaction is conducted at a temperature of 25°C for a time ranging from 10 to 30 hours.
5. The process of claim 3 wherein the reaction is conducted at a temperature of 37°C for a time ranging from 30 to 60 minutes.
6. The process of claim 1 wherein said polyamide material is selected from the group consisting of aliphatic nylon and aromatic nylon.
7. The process of claim 6 wherein said aliphatic nylon is polycaprolactam.
8. A shaped biocompatible article of manufacture from a polyamide that has been prepared according to the process of claim 1.
9. The shaped biocompatible article of claim 8 in the form of a prothesis or a membrane.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT22222/78A IT1095574B (en) | 1978-04-12 | 1978-04-12 | PROCEDURE FOR THE PREPARATION OF BIOCOMPATIBLE MATERIALS OF A POLYAMIDE NATURE AND MANUFACTURES SO OBTAINED |
| IT22222A/78 | 1978-04-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1117696A true CA1117696A (en) | 1982-02-02 |
Family
ID=11193262
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000325378A Expired CA1117696A (en) | 1978-04-12 | 1979-04-11 | Process for producing biocompatible materials of a polyamide type and articles obtained thereby |
Country Status (21)
| Country | Link |
|---|---|
| US (1) | US4336357A (en) |
| JP (1) | JPS54137096A (en) |
| AU (1) | AU526718B2 (en) |
| BE (1) | BE875500A (en) |
| CA (1) | CA1117696A (en) |
| CH (1) | CH638821A5 (en) |
| CS (1) | CS226004B2 (en) |
| DD (1) | DD142842A5 (en) |
| DE (1) | DE2914018C3 (en) |
| DK (1) | DK140479A (en) |
| FR (1) | FR2422697A1 (en) |
| GB (1) | GB2018791B (en) |
| HU (1) | HU180522B (en) |
| IL (1) | IL57027A (en) |
| IT (1) | IT1095574B (en) |
| LU (1) | LU81140A1 (en) |
| NL (1) | NL174650C (en) |
| NO (1) | NO147232C (en) |
| SE (1) | SE7903262L (en) |
| YU (1) | YU86179A (en) |
| ZA (1) | ZA791652B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0182784A1 (en) * | 1984-06-14 | 1986-06-04 | Bioresearch Inc. | Composite surgical sutures |
| JPH0796617B2 (en) * | 1984-10-29 | 1995-10-18 | メムテツク リミテツド | Sulfuryl chloride-polyamide derivative |
| DE4120723A1 (en) * | 1991-06-22 | 1992-12-24 | Basf Ag | PROCESS FOR THE SURFACE TREATMENT OF POLYAMIDE MOLDED BODIES AND MOLDED BODY OBTAINED THEREFORE |
| US6547768B2 (en) | 2000-12-14 | 2003-04-15 | Cordis Corporation | Medical devices with reduced friction polyamides, and method |
| US9168695B2 (en) * | 2006-12-18 | 2015-10-27 | Unitika Ltd. | Biaxially stretched polyamide resin film and production method thereof |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE455654A (en) * | 1941-07-10 | |||
| GB670693A (en) * | 1947-10-10 | 1952-04-23 | Edward Erlick Verdiers | Treatment of waste fibrous materials of synthetic origin |
| GB734493A (en) * | 1951-05-08 | 1955-08-03 | Raduner & Co Ag | Improvements in or relating to a process of improving synthetic polyamide fibre materials |
| US2876524A (en) * | 1954-12-08 | 1959-03-10 | Univ Minnesota | Method of altering the physical characteristics of linear condensation polymers withanhydrous hydrogen halide gas |
| US3075823A (en) * | 1957-08-21 | 1963-01-29 | Univ Minnesota | Method of treating water-insoluble linear polyamide condensation polymers with anhydrous hydrogen halide gas and then moisture to hydrolyze the polyamide surface |
| US3011915A (en) * | 1958-03-17 | 1961-12-05 | Capskar Inc | Method of coating cloth with a nylon solution |
| US3060550A (en) * | 1959-03-27 | 1962-10-30 | American Enka Corp | Treatment of polyamides |
| NL299806A (en) * | 1962-11-07 | |||
| AT237903B (en) * | 1963-02-12 | 1965-01-11 | Leuna Werke Veb | Process for reducing the relative viscosity of polyamides produced by alkaline polymerization |
| CH1373768D (en) * | 1967-04-24 | |||
| CA953054A (en) * | 1970-06-05 | 1974-08-20 | Fmc Corporation | Method of forming structures from microcrystalline collagen |
| FR2098753A5 (en) * | 1970-07-15 | 1972-03-10 | Inst Bezinovoi | |
| IL42516A (en) * | 1973-06-15 | 1976-11-30 | Mordechai Sokolovsky | Polyamides substituted with aldehyde and isonitrile residues and process for the production of same |
| IT1085524B (en) * | 1977-03-22 | 1985-05-28 | Snam Progetti | BIOCOMPATIBLE POROUS MATERIALS AND FIBERS ABLE TO ENGLISH SUBSTANCES OF BIOLOGICAL INTEREST AND METHODS FOR OBTAINING THEM |
-
1978
- 1978-04-12 IT IT22222/78A patent/IT1095574B/en active
-
1979
- 1979-04-03 AU AU45733/79A patent/AU526718B2/en not_active Ceased
- 1979-04-05 DK DK140479A patent/DK140479A/en not_active IP Right Cessation
- 1979-04-06 ZA ZA791652A patent/ZA791652B/en unknown
- 1979-04-06 CH CH325779A patent/CH638821A5/en not_active IP Right Cessation
- 1979-04-06 NO NO791164A patent/NO147232C/en unknown
- 1979-04-06 DE DE2914018A patent/DE2914018C3/en not_active Expired
- 1979-04-09 IL IL57027A patent/IL57027A/en unknown
- 1979-04-10 GB GB7912612A patent/GB2018791B/en not_active Expired
- 1979-04-11 YU YU00861/79A patent/YU86179A/en unknown
- 1979-04-11 SE SE7903262A patent/SE7903262L/en not_active Application Discontinuation
- 1979-04-11 HU HU79SA3174A patent/HU180522B/en unknown
- 1979-04-11 BE BE0/194545A patent/BE875500A/en not_active IP Right Cessation
- 1979-04-11 CA CA000325378A patent/CA1117696A/en not_active Expired
- 1979-04-11 LU LU81140A patent/LU81140A1/en unknown
- 1979-04-11 FR FR7909218A patent/FR2422697A1/en active Granted
- 1979-04-12 JP JP4369079A patent/JPS54137096A/en active Pending
- 1979-04-12 DD DD79212190A patent/DD142842A5/en unknown
- 1979-04-12 NL NLAANVRAGE7902923,A patent/NL174650C/en not_active IP Right Cessation
- 1979-04-12 CS CS792518A patent/CS226004B2/en unknown
-
1980
- 1980-07-28 US US06/172,957 patent/US4336357A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| YU86179A (en) | 1983-12-31 |
| HU180522B (en) | 1983-03-28 |
| IL57027A0 (en) | 1979-07-25 |
| GB2018791A (en) | 1979-10-24 |
| NL174650C (en) | 1984-07-16 |
| DD142842A5 (en) | 1980-07-16 |
| IT7822222A0 (en) | 1978-04-12 |
| IL57027A (en) | 1982-09-30 |
| DE2914018C3 (en) | 1982-04-22 |
| FR2422697A1 (en) | 1979-11-09 |
| AU526718B2 (en) | 1983-01-27 |
| US4336357A (en) | 1982-06-22 |
| NL174650B (en) | 1984-02-16 |
| JPS54137096A (en) | 1979-10-24 |
| CS226004B2 (en) | 1984-03-19 |
| DE2914018B2 (en) | 1981-05-14 |
| SE7903262L (en) | 1979-10-13 |
| NO791164L (en) | 1979-10-15 |
| NL7902923A (en) | 1979-10-16 |
| NO147232B (en) | 1982-11-22 |
| IT1095574B (en) | 1985-08-10 |
| NO147232C (en) | 1983-03-02 |
| BE875500A (en) | 1979-10-11 |
| DK140479A (en) | 1979-10-13 |
| ZA791652B (en) | 1980-04-30 |
| GB2018791B (en) | 1983-02-09 |
| CH638821A5 (en) | 1983-10-14 |
| AU4573379A (en) | 1979-10-18 |
| FR2422697B1 (en) | 1983-10-28 |
| DE2914018A1 (en) | 1979-10-31 |
| LU81140A1 (en) | 1979-06-19 |
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