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WO1996008211A2 - Procedes et composes de greffage au plasma - Google Patents

Procedes et composes de greffage au plasma Download PDF

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Publication number
WO1996008211A2
WO1996008211A2 PCT/US1995/011253 US9511253W WO9608211A2 WO 1996008211 A2 WO1996008211 A2 WO 1996008211A2 US 9511253 W US9511253 W US 9511253W WO 9608211 A2 WO9608211 A2 WO 9608211A2
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WO
WIPO (PCT)
Prior art keywords
plasma
amine
protected
grafting
membrane
Prior art date
Application number
PCT/US1995/011253
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English (en)
Other versions
WO1996008211A3 (fr
Inventor
Eric K. Dolence
Chen-Ze Hu
Clifton G. Sanders
Shigemasa Osaki
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Surface Engineering Technologies, Division Of Innerdyne, Inc.
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Application filed by Surface Engineering Technologies, Division Of Innerdyne, Inc. filed Critical Surface Engineering Technologies, Division Of Innerdyne, Inc.
Publication of WO1996008211A2 publication Critical patent/WO1996008211A2/fr
Publication of WO1996008211A3 publication Critical patent/WO1996008211A3/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0081—After-treatment of organic or inorganic membranes
    • B01D67/0093—Chemical modification
    • B01D67/00931—Chemical modification by introduction of specific groups after membrane formation, e.g. by grafting
    • 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
    • A61L33/0082—Chemical modification of the substrate by reacting with an organic compound other than heparin
    • 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
    • A61L33/0094—Physical treatment, e.g. plasma treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J19/12—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electromagnetic waves
    • B01J19/122—Incoherent waves
    • B01J19/126—Microwaves
    • 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
    • C08J7/16—Chemical modification with polymerisable compounds
    • C08J7/18—Chemical modification with polymerisable compounds using wave energy or particle radiation
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N11/00—Carrier-bound or immobilised enzymes; Carrier-bound or immobilised microbial cells; Preparation thereof
    • C12N11/02—Enzymes or microbial cells immobilised on or in an organic carrier
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N11/00—Carrier-bound or immobilised enzymes; Carrier-bound or immobilised microbial cells; Preparation thereof
    • C12N11/02—Enzymes or microbial cells immobilised on or in an organic carrier
    • C12N11/08—Enzymes or microbial cells immobilised on or in an organic carrier the carrier being a synthetic polymer
    • C12N11/089—Enzymes or microbial cells immobilised on or in an organic carrier the carrier being a synthetic polymer obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
    • G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
    • G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
    • G01N33/54353—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals with ligand attached to the carrier via a chemical coupling agent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/38—Graft polymerization
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0894—Processes carried out in the presence of a plasma

Definitions

  • Adsorption of proteins is normally one of the first events to occur when blood contacts a foreign surface.
  • the composition and conformation of adsorbed proteins influence subsequent cellular responses such as platelet adhesion, aggregation, secretion, complement activation, and ultimately, the cross-linked fibrin formation and thrombus formation.
  • the initial protein layer at the blood-material interface is subject to denaturation, replacement, and further reaction with blood components.
  • adsorbed fibrinogen is converted to fibrin.
  • Fibrin formation is accompanied by the adherence of platelets and possibly other cellular componenets.
  • the platelets become activated and release the contents of their granules. This activates other platelets, thereby resulting in platelet aggregation.
  • a thrombus eventually forms from entrapment of erythrocytes (red blood cells) and other blood constituents in the growing fibrin network. Thrombus growth can eventually lead to partial or even total blockage of the device unless the thrombus is sheared off or otherwise released from the foreign surface as an embolus.
  • emboli can be as dangerous as blockage of the device because emboli can travel through the blood-stream, lodge in vital organs, and cause infarction of tissues. Infarction of the heart, lungs, or brain, for example, can be fatal. Therefore, the degree to which foreign material used in biomedical implants inhibits thrombus formation, embolization, and protein denaturation determines its usefulness as a biomaterial.
  • bioactive molecules include anticoagulants, such as heparin.
  • Heparin is a highly sulfonated mucopolysaccharide containing a number of charged functional groups.
  • the heparin/antithrombin III complex formed inactivates Factor Xa.
  • Factor Xa is responsible for the conversion of prothrombin to thrombin which mediates the conversion of fibrinogen to fibrin (8).
  • bioactive molecules by physical adsorption or entrapment beneath the blood-contacting surface exhibit a significant degree of thromboresistance.
  • depletion of the bioactive molecules by leaching into the blood environment causes the surface to rapidly lose its thrombo-resistant character. Entrained molecules diffuse to the surface which, along with physically adsorbed bioactives, are then "leached" from the surface into the blood plasma by mechanical and chemical mechanisms.
  • electrostatically or ionically bound molecules are subject to partitioning and ion exchange between the blood-contacting surface and the electrolyte-rich plasma resulting in depletion.
  • Covalently bound bioactive molecules resist depletion sufficiently to offer a potentially "long term" thromboresistant effect.
  • Most prior attempts to covalently bind heparin to a blood-contacting surface have reportedly resulted in severely decreased activity of the bound heparin.
  • heparin coupled to a blood-contacting surface through one of its carboxyl groups using a carbodiimide method has been reported to lose up to 90% of its activity (9).
  • Others have reported "covalent” attachment of heparin, but actually describe heparin covalently bound to a tether molecule which is ionically bound to the substrate (10).
  • siloxane polymers are of particular interest in blood gas exchange devices due to their inherent thromboresistant properties and gas permeability (11). Siloxane polymers, however, are relatively inert and thus relatively resistant to modification of their surfaces except for the use of ionizing radiation or free-radical initiators in the presence of a vinylic monomer (11-17).
  • th use of plasma discharge processes provide one technique for altering the surface chemistry of silicones (18) and other polymeric materials (19-26).
  • Coating refers to the ability to lay down on a surface by a plasma polymerization process a film of polymerized monomer.
  • the coating process described in co-assigned, co-pending U.S. Application filed November 12, 1993, entitled "Hydrocyclosiloxane Membrane Prepared by Plasma Polymerization Process,” is one example of a coating process. In that process, a siloxane film is deposited on a surface.
  • Other monomers used in coating processes include octamethylcyclotetrasiloxane (33), ethylene (34), fluorocarbons (35) and others.
  • coating is defined as application of a film or layer of deposited polymerized monomer forming a "skin" or membrane over the substrate. In applications where for example gas transfer is a desired property, a "skin" of polymer may disrupt or abolish desirable gas transfer properties.
  • Etching is a process of cleaning a surface which is analogous to "surface ablation” and is commonly used for metals (36).
  • a common monomer used for "etching” is argon gas.
  • Plasma derived from argon is high energy and has the ability to remove molecular species from the surface exposing substrate that was located under the surface prior to treatment. This process is particularly useful for the removal of organic contaminates.
  • Grafting refers to the ability to attach by end-point attachment individual molecules of a monomer used in a plasma process. End point attachment is important because the unattached end of the molecule can be used to conduct further chemical modification. For example with a tether molecule, one end is attached to the surface leaving the other end of the tether extending away from the surface. The extended end can be chemically modified to attach a biomolecule.
  • a plasma glow zone is created by passing monomer molecules through a high frequency (13.6 MHz radio frequency power supply is used in this invention) electric field at pressures lower than atmospheric pressure. Electrons under the influence of the electric field will interact with the monomer molecules and gain kinetic energy. A low temperature plasma will form when the energetic electrons collide with the monomer molecules. A plasma is composed of electrons, free radicals and molecules in the excited state.
  • the general process of creating a low temperature plasma is known to those in the art (37-39) and accordingly, a detailed discussion of the theory behind plasma processes is not provided here.
  • Plasma grafting is a process of passing a monomer species through a plasma glow zone which generates free radicals. At the same time the substrate either sits in the glow zone (batch type reactor) or is continously feed
  • the substrate During the time that the substrate resides in the plasma glow zone, the substrate is bombarded by electrons and ions. When the electrons become energetic enough, chemical bonds are broken in the top layers of the substrate becoming chemically active due to radical anions or cations.
  • the free radicals generated have longer lifetimes than free radicals generated in the atmosphere.
  • the majority of free radicals generated in the glow zone will recombine with each other forming low molecular weight oligomers. Only a fraction of free radicals will interact with the chemically activated substrate surface.
  • covalent bonds are formed between the monomer molecules and the polymeric substrate through free radical mechanisms.
  • the surface of the substrate is grafted with monomer molecules which has a desired functional group for further chemical manipulation by wet chemistry processes.
  • the present invention is directed to methods for producing a surface suitable for immobilizing a biomolecule onto the surface.
  • the methods are particularly useful for those surfaces used in constructing biomedical devices and implants.
  • a variety of bioactive molecules for example, those which counteract specific blood-foreign material incompatibility reactions, may be immobilized onto the surface.
  • the present invention pertains to the use of N-protected unsaturated or cyclic amines (see Figure 2) to plasma graft amine groups onto a surface. Increasing interest in the synthesis and use of N-silylated amines have recently been reported.
  • siloxane is a preferred substrate because the substrate itself is relatively thromboresistant. Moreover, siloxane is gas permeable, which is important in many applications, for example, in gas exchange devices. Nevertheless, it will be appreciated that other substrates are within the scope of the present invention. It will also be appreciated that methods and grafted surfaces involving biomolecules other than those which counteract blood-foreign material incompatibility are within the scope of the present invention.
  • Plasma processes on various substrates can be characterized using the surface analysis methods known as ESCA43 (electron spectroscopy for chemical analysis) and TIRF44 (Total internal reflection fluorescence) for primary amine containing surfaces.
  • TMCTS siloxane surfaces can initially be analyzed looking at specifically the elements of silicone, carbon, nitrogen and oxygen. The atomic percentages of silicone, carbon, nitrogen and oxygen are typically 33%, 33%, 0% and 33%. After grafting using N-trimethylsilylallylamine (TMSAA) and treating the 1,3,5,7-tetramethylhydrocyclosiloxane
  • TMSAA N-trimethylsilylallylamine
  • TCTS surface atomic percentage for nitrogen
  • the surface atomic percentage for nitrogen is typically in the 4-8% range. This means that 4-8 % nitrogen has been introduced on the surface. It can not be stated that all of this nitrogen will be useful for chemical modification which would involve only primary and secondary amines as nucleophiles capable of reacting.
  • TIRF spectroscopy using the fluoroprobe fluorescamine (45) generates a fluorescent adduct only upon reaction with a primary amino groups. Accordingly, TIRF can be used to determine if primary amino groups are present on a grafted surface.
  • the present invention pertains to the use of N-protected unsaturated or cyclic amines to plasma graft amine groups onto a surface, for example, a siloxane surface, thus rendering the surface capable of bonding to a tether or bioactive molecule.
  • amine groups are introduced onto the surface using a plasma grafting process. In a plasma grafting process a reactive molecule is introduced onto the substrate surface.
  • the unsaturated or cyclic amine-containing compound is 'activated' by the electrode of the plasma appartaus resulting in generation of a radical or similar reactive intermediate by homolytic or heterolytic cleavage of the carbon-carbon double bond, carbon-carbon triple bond or strained carbocyclic ring system.
  • the reactive intermediate then undergoes silicon-hydrogen and/or carbon-hydrogen insertion on a siloxane substrate surface.
  • the siloxane surface may also be 'activated' by the electrode possibly generating radicals on the surface.
  • Other polymeric materials and other substrates may be treated by only slight modifications of existing methods. By this method, as will be later discussed in detail, the amine-containing compound is attached to the surface.
  • the surface may be reacted with epoxide-, isocyanate-terminated or other electrophilic-terminated poly-(ethylene) oxide (hereinafter referred to as "PEO") tether molecules.
  • PEO electrophilic-terminated poly-(ethylene) oxide
  • Polyethylene oxide is presently preferred because it exhibits low protein adsorption.
  • Other molecules may be used as "spacer or tether chains," as well.
  • these can include peptides, polypeptides, long chain alkanes, proteins, polysaccharides, saccharides, fatty acids, poly(amino acids), poly(vinyl alcohols), poly (vinyl pyrrolidinones), polyphosphazenes, poly(acrylic acid) and other biologically derived polymers.
  • the intact electrophilic group on the PEO that is surface bound may react with the nucleophilic groups (hydroxyl, amine, sulfhydryl) present in biomolecules and pharmaceutical agents.
  • nucleophilic groups hydroxyl, amine, sulfhydryl
  • various bioactive molecules may be covalently bonded to one end of the PEO molecule in the same way that the other end of the PEO molecule is covalently bonded to the siloxane blood-contacting surface.
  • the bioactive molecule may possess an activity approaching the activity of the bioactive molecule in solution. Because of the mobility of the bioactive molecules near the surface, the effectiveness of the bioactive molecule may be substantially greater than the same bioactive molecule bound directly to the surface or by a very short tether molecule. (47) For these reasons, this embodiment may be preferred.
  • Bioactive molecules which may be immobilized on a surface include: heparin, urokinase, plasmin, and tissue plasminogen activator (TPA), streptokinase, albumin, IgG, hirudin, other proteins, modified prostaglandins and other pharmaceuticals.
  • Heparin inhibits the blood incompatibility reaction which normally causes clotting and thromboemboli formation. Heparin acts by interacting with antithrombin III, Factor Xa and thrombin to inhibit the conversion of fibrinogen to fibrin.
  • Urokinase, plasmin, and TPA are serine proteases which lyse protein deposits and networks formed during blood incompatibility reactions that lead to thrombosis.
  • Figure 1 depicts plasma processes: coating, etching and grafting
  • Figure 2 depicts monomer candidates for plasma grafting agents as the mono-N-trimethylsilyl protected analogs
  • FIG. 3 depicts modified electrodes configuration of the Plasma Science 0500 plasma system
  • FIG. 4 depicts engineering STAR-PL plasma system
  • Figures 5A to 5D depict ESCA spectra of two minute ammonia grafting of tetramethylhydrocyclosiloxane (TMCTS) coated KPF-190 fiber
  • FIGS 6A to 6D depict ESCA spectra of two minute ammonia grafting of tetramethylhydrocyclosiloxane (TMCTS) coated KPF-190 fiber following water treatment
  • FIGS 7A to 7D depict ESCA spectra of two minute allylamine grafting of a tetramethyldisiloxane (TMDS) surface following a dichloromethane wash
  • FIGS 8A to 8D depict ESCA spectra of two minute allylamine grafting of a tetramethyldisiloxane (TMDS) surface following water wash
  • Figure 9 depicts a reaction scheme and reagent stochiometry used in the synthesis of N-trimethylsilylallylamine
  • FIGS 10A to 10C depict ESCA spectra of tetramethylhydrocyclosiloxane (TMCTS) plasma coated KPF-190 polypropylene fiber
  • Figures 11A to 11D depict ESCA spectra of TMCTS coated KPF-190 fiber grafted with N-trimethylsilylallylamine using the STAR-PL plasma grafting system
  • Figures 12A to 12D depict ESCA spectra of TMCTS coated KPF-190 fiber grafted with N-trimethylsilylallylamine using the STAR-PL plasma grafting system followed by water treatment
  • FIGS 13A to 13D depict ESCA spectra of TMCTS coated KPF-190 fiber grafted with N-trimethylsilylallylamine using the Plasma Science 0500 plasma grafting system
  • Figures 14A to 14D depict ESCA spectra of TMCTS coated KPF-190 fiber grafted with N-trimethylsilylallylamine using the Plasma Science 0500 plasma grafting system followed by water treatment
  • Figures 15A to 15D depict ESCA spectra of TMCTS coated quartz slide grafted fifty seconds with N-trimethylsilylallylamine using the Plasma Science 0500 plasma grafting system
  • Figure 16 depicts surface fluorescence of a fluorescamine treated tetramethylhydrocyclosiloxane coated quartz slide grafted for 50 seconds using
  • TMSAA N-trimethylsilylallylamine
  • Figure 17 depicts ESCA spectra of polystyrene spin-coated quartz slide
  • Figures 18A to 18D depict ESCA spectra of polystyrene spin-coated quartz slide grafted fifty seconds with N-trimethylsilylallylamine using the Plasma Science 0500 plasma grafting system
  • Figure 19 depicts surface fluorescence of a fluorescamine treated polystyrene spin-coated quartz slide grafted for 50 seconds using N-trimethylsilylallylamine (TMSAA) versus a non-grafted polystyrene control
  • TMSAA N-trimethylsilylallylamine
  • Figures 20A to 20C depict Carbon-13 nuclear magnetic resonance spectrum of STAR-PL deposited oligomer
  • Figures 21A to 21G depict Carbon-13 nuclear magnetic resonance spectrum of STAR-PL deposited oligomer-95% carbon-13 HPEO reaction product
  • N-protected unsaturated or cyclic amine allows the achievement of desirable end-point attachment.
  • carbon end-point attachment offers the advantage of preserving the nucleophilic group intact for further chemical elaboration.
  • use of N-protected amines as plasma grafting agents with siloxane substrates protects these normally pH sensitive surfaces from extensive damage due to the basicity of amines. This observation has allowed the application of the N-trimethylsilylallylamine (TMSAA) grafting process to siloxane coated hollow fiber in a gas transfer application without critical loss of gas permeability as compared with an allylamine or ammonia grafting processes.
  • TMSAA N-trimethylsilylallylamine
  • optimal conditions for maximizing the amount of primary and possibly secondary amines produced during plasma grafting. This is important because only primary and secondary amines are useful for covalent coupling appropriate electrophilic agents such as mixed carbonates, active esters, isocyanates, isothiocyanates, epoxides and other electrophiles.
  • optimal conditions is meant those conditions which maximize water stability (i.e., minimize the amount of nitrogen lost upon water exposure as monitored by ESCA analysis); those conditions which maximize nitrogen available to react with a tether or spacer (i.e., maximize available primary and secondary amino groups); those conditions which minimize gas permeability degradation as a result of grafting.
  • the optimal conditions chosen are a function of several variables. The most important is the type of plasma reactor apparatus (plate reactor, tube type reactor, or other configurations) and its construction geometry. Two types of plasma reactors are utilized in this invention.
  • the internal electrode R.F. plasma reactor is a plate type reactor depicted in Figure 3.
  • This system is a modified Plasma Science 0500 plasma system (PL-0500) that is a capacitively coupled with an internal electrode radio frequency system (Plasma Science, Inc, 272 Harbor Boulevard, Belmont, CA 94002).
  • the reactor consists of a hot electrode 1 and the ground electrode 2 with an electrode size of 14.75 inches by 17 inches. Both electrodes are located inside of the vacuum system and are located 5 inches apart.
  • the radio frequency (R.F.) system which includes the 13.6 MHz power generator 7 , matching network 6 and R.F. cable 5, are connected to the hot electrode 1 through the R.F. cable 5 and the electrical ground 2 through the R.F.
  • a fixed amount of monomer is fed continuously from the monomer reservoir 4, through the mass flow controller 3, into the plasma chamber 13 and pumped out of the plasma chamber 13 through the output port 8.
  • the unused monomer is condensed in the liquid nitrogen cold trap 11.
  • the PL-0500 is a batch type plasma reactor.
  • the substrate to be plasma grafted is placed in the space located between the hot and ground electrodes.
  • the plasma chamber 13 is pumped down by opening the gate valve 9 .
  • the gate valve 9 is located in between the pump system and the plasma chamber 13. After opening the gate valve 9 , the pressure of the plasma chamber 13 will drop to the millitorr range and reaches a steady state equilibrum pressure within a few minutes.
  • the mass flow controller is turned on and the monomer is fed from the monomer reservoir 4 into the plasma chamber 13.
  • the throttle valve 10 is then turned on to regulate and maintain a constant pressure in the plasma chamber 13.
  • the plasma glow zone is activated in the space located between the hot electrode 1 and the ground electrode 2 by introducing the R.F. power into the hot electrode 1 .
  • the plasma glow zone can be viewed through the view port 4.
  • the R.F. power is turned off and the grafted substrate is allowed to remain inside of the system for two minutes, a post monomer quench, to eliminate radical species that have activated the substrate surface.
  • the mass flow controller 3 and the throttle valve 10 are closed.
  • the residual monomer is continuously pumped out of the plasma chamber 13 through the gate valve 9 .
  • the gate valve 9 is then closed and the plasma chamber 13 is vented to the atmosphere by opening the vent valve 14.
  • the plasma grafted substrate can then be removed from the plasma chamber.
  • the STAR plasma coating system is an external electrode radio frequency plasma system that has been developed in-house and is depicted in Figure 4. This system is capacitively coupled and is designed for the continuous plasma grafting of substrates such as fibers and catheter tubing.
  • the STAR-PL system continuously grafts substrate by drawing the substrate through the plasma glow zone.
  • the plasma glow zone is controlled by parameters such as radio frequency (R.F.) power, monomer flow rate, system pressure and the substrates dwell time in the plasma glow zone.
  • R.F. radio frequency
  • the STAR-PL systems consists of two chambers and a plasma glow zone.
  • Chamber .14. contains a supply spool 10, pulleys 9 and clutch 21.
  • Chamber 15 contains take-up spool 11, pulleys 9 and a coating speed control pulley 16.
  • the fiber or catheter tubing 5 is wound onto the supply spool 10.
  • the fiber or catheter tubing is tied with 15 turns of extra guide thread.
  • a loop is formed between the supply spool 10, the chamber 14, the plasma glow zone 6, the chamber 15, pulleys 9 and the take-up spool 11 with the aid of the guide thread.
  • the fiber or catheter will pass through the Pyrex ® glass tube 7 three times before winding up on the take-up spool 11.
  • the monomer is fed form the monomer reservoir 12 into the system through the mass flow controller 13, the chamber 14, the plasma glow zone 6, the chamber 15 and is continuously pumped out through the outlet port 17.
  • the unreacted monomer is condensed out at the liquid nitrogen trap system 20.
  • the system pressure is controlled by the throttle valve 18.
  • the plasma glow zone consists of a Pyrex ® glass tube 7 with the R.F. electrode 4 attached to the exterior glass surface and the ground electrode 22 attached to the R.F. shielding box 8.
  • the R.F. shielding box 8 is attached to both chambers 14 and 15.
  • the plasma glow zone 6 is activated inside of the Pyrex ® glass tube 7 .
  • the R.F. system which supplies the power to maintain the plasma glow zone, includes the R.F. power supply 1 , the R.F. cable 2 , the R.F. matching network 3, the R.F. electrodes 4, and the ground electrode 22.
  • the electrodes are made of 1 inch wide copper tape.
  • the proper substrate tension is maintained by the clutch 21 and the speed of the substrate is measured by the speed control pulley 16.
  • the plasma grafted substrate is continuously wound onto the take-up spool 11. After the plasma grafting is completed, the R.F. power supply 1 , mass flow controller 13 and the throttle valve 18 are closed. The system is vented to the atmosphere and the plasma grafted substrate spools can be removed from the system.
  • Preferred N-protected unsaturated and cyclic amines include compounds selected from
  • R 1 is -CH 2 - or -CH(CH 3 )-
  • R 2 is hydrogen, lower alkyl, tri-loweralkylsilyl or lower alkylsilane and R 3 is tri-lower alkylsilyl or a lower alkylsilane group.
  • the N-protected amine is a mono- or bis- N-triloweralkylsilylallylamine.
  • Preferred lower alkyl groups include methyl and ethyl.
  • Other protecting groups may be used which are removable under mild, non- oxidizing conditions by a chemical means and include, e.g., acetyl, trifluoroacetyl and others known in the art.
  • Appropriate N-protecting groups include groups which would give sufficient vaporpressure to be put in a gas phase for plasma grafting.
  • N-trimethylsilyl protected unsaturated and cyclic amines As described herein, we have found N-trimethylsilyl protected unsaturated and cyclic amines to be particularly preferred, more particularly mono and bis brimethylsilylallyl amines.
  • the substrate can play an important part in the conditions that can be utilized. Many substrates are very sensitive to temperature and UV radiation and are easily damaged. For these two important reasons, one can not make generalizations which would make it easy to predict results of a grafting process without considerable experimentation.
  • the variables involved in plasma grafting are geometry dependent based on the reactor design. However, the values of the variables are not unique, simply the correct combination of variables must be found. Typically, this is determined using a response-surface approach.
  • the methods of the present invention involve introducing amine groups on a surface by plasma grafting using a gas of an N-protected unsaturated or cyclic amine.
  • a gas of an N-protected unsaturated or cyclic amine In one plasma grafting process, microporous hollow fibers coated with a plasma-polymerized tetramethylhydrosiloxane are used as the substrate. These fibers are subjected to additional plasma exposure in the presence of gas of an N-protected unsaturated amine, N-trimethylsilylallylamine (TMSAA).
  • N-protected unsaturated amines in plasma grafting to attach functional amine groups to the siloxane substrate, as discussed below, is an important improvement within the scope of the present invention.
  • Several advantages have been found in employing N-protected unsaturated amines in a plasma grafting process.
  • reaction of a nucleophilic group (amino) covalently bound to the surface with electrophilic tether followed by an appropriate biomolecule produces a bioconjugate in which a strong covalent bond is formed.
  • the type of bond formed in this process is a function of the type of starting electrophilic group present on the PEO molecule.
  • an amino group reacting with PEO bis-glycidyl ether an alpha-amino alcohol is formed.
  • Reaction of an amino nucleophile with a PEG mixed carbonate produces an urethane or carbamate covalent bond.
  • Example 1 Ammonia Plasma Treatment of a
  • Example 2 Ammonia Plasma Treatment of Tetramethylhydro- cyclotetrasiloxane Coated KPF-190 Fiber
  • TCTS tetramethyltetrahydrocyclosiloxane
  • N-trimethylsilyl derivative A common theme in organic synthesis is to protect amino groups with a protecting group such that other chemical manipulation can be made on a molecule without interference from the amino nucleophile. After such modifications the protecting group is removed from the amino group. In an attempt to modify the plasma grafting ability of allylamine, the amino nitrogen was protected as the N-trimethylsilyl derivative.
  • N-Trimethylsilylallylamine was synthesized based on the procedure described in the literature63 and is described in detail below. Other N-trimethylsilylated amines may be synthesized from the parent amine by modification of the below described procedure followed by distillation.
  • HMDS hexamethyldisilazane
  • the concentration for the test sample is 0.05 mL of TMSAA in 0.55 mL of deuterated chloroform.
  • the internal reference for proton NMR is the residual non-deuterated chloroform signal located at 7.26 ppm.
  • the internal reference for carbon NMR is the deuterated chloroform signal triplet signal located at 77.0 ppm.
  • the internal reference for silicon NMR is tetramethylsilane located at 0.00 ppm.
  • NMR data is as follows: 1 H NMR (CDCl 3 ) ⁇ 7.26 (singlet, internal reference CHCl 3 ) 5.95-5.78 (multiplet, 1 H, olefinic proton), 5.14-4.90 (multiplet, 2 H, terminal olefinic protons), 3.36-3.26 (multiplet, 2 H, allylic protons), 0.70-0.20 (broad singlet, 1 H, NH proton), 0.03 (singlet, 9 H, (CH 3 ) 3 Si); 13 C NMR (CDCl 3 ) ⁇ 140.8 (olefinic carbon), 112.8 (olefinic carbon), 77.0 (triplet center signal, internal reference CDCl 3 ), 44.5 (allylic carbon), 2.4 (trace 1,1,1,3,3,3-hexamethyldisilazane impurity, this signal must not be larger than the 44.5 ppm signal), 0.1 (methyl carbon from the trimethylsilyl group); 29 Si NMR (CDCl 3 ) ⁇ 4.
  • N-trimethylsilylallylamine may be purchased from HULS America, Inc., Piscataway, NJ.; however, quality must be monitored carefully.
  • Synthesized N-trimethylsilylallylamine used in the plasma grafting process may contain up to 15% 1,1,1,3,3,3- hexamethyldisilazane impurity without affecting the quality of grafting results. In fact, attempts to utilize 1,1,1,3,3,3-hexamethyldisilazane as a grafting agent did not result in the implantation of nitrogen on the surface.
  • Table 4 and Figures 10A to 14D describe plasma grafting using N-trimethylsilylallylamine on tetramethyl- hydrocyclotetrasiloxane KPF-190 polypropylene fiber.
  • use of N-trimethylsilylallylamine afforded quite different results than examples 1 to 3.
  • Table 4 includes data utilizing both the Plasma Science 0500 and STAR plasma units which demostrates that the conditions used to obtain similar results from the different geometrically configured machines can vary. Conditions used in grafting is configuration dependent. The ESCA data reveals that following water treatment the amount of nitrogen lost to hydrolysis is at most 11%.
  • Atomic percentages are listed in Table 5. For the time values of 10 to 90 seconds little difference exists in the percentage of nitrogen introduced ranging from 9 to 10.5 atomic percentage.
  • Preliminary qualitative TIRF data for the 50 second sample is depicted in Figure 16 clearly demonstrates the presence of surface fluorescence indicating that primary amino groups are present on the surface as compared to an ungrafted control.
  • ESCA data for the 50 second sample used before and after water exposure are summarized in Table 5.
  • Example 7 N-Trimethylsilyl Allylamine Plasma Treatment of Polystyrene (MW 250.000) Film Cast on a Quartz Slide-50 Second Grafting Exposure
  • polystyrene film was spin-cast on a quartz TIRF slides using a 3% solution of polystyrene (molecular weight 250,000) in toluene.
  • the spin cast film/slide was then inspected by ESCA as depicted in Figures 17A to 17D and summarized in Table 6.
  • the polystyrene slide was then subjected to the following grafting conditions using the Plasma Science 0500 reactor and inspected by ESCA to determine atomic percentages as depicted in Figures 18A to 18D and Table 6.
  • the grafted surface reveals not only the incorporation of nitrogen but also oxygen.
  • the presence of oxygen must arise due to incorporation during the grafting process (due to imperfect seals leading to oxygen leaking into the system) or upon shut-down of the system and exposure to the atmosphere.
  • oxygen is being trapped by the radicals formed during the grafting process or generated on the surface.
  • a non-oxygen containing substrate such as polystyrene
  • oxygen incorporation was not noticed due to the substrates high oxygen content.
  • the presence of oxygen is not detrimental to the ability of the amino groups to react with fluorescamine .
  • oligomeric material arising from gas phase reaction of ionized monomer with itself . Since grafting on a surface can not be identified and structurally characterized on a surface by classical methods such as nuclear magnetic resonance spectroscopy, the depositied oligomeric polymer should in some degree reflect the structural identification of the grafted species on the surface. In order to learn more about the structural features of the grafting species, the deposited oligomer was investigated by spectroscopic methods and the chemistry of the oligimer probed.
  • the oligomer deposited in the downstream vacuum portion of the tube of the STAR system is typically a gummy, amber colored resin.
  • the Fourier transform infrared spectrum reveals that the oligomer is an alkane (2954 cm -1 ) which contains amino and or hydroxyl groups (3279 cm -1 ) in addition to a possible silyl ether being present (1251 cm -1 ). More detailed structural information on the oligomer can be obtained using nuclear magnetic resonance spectroscopy.
  • This oligomer is soluble in organic solvents such as chloroform and alcohols such as methanol, however it takes considerable time for dissolution to occur.
  • the STAR oligimer contains three magnetically distinct silicon atoms. Most importantly is the signals located between -20 and -23 ppm which suggest that the silicon is bound with oxygen. This confirms the incorporation of oxygen into the grafting as was discussed in Example 8 involving polystyrene. The broad nature of the oligomer silicon signals suggest that the silyl groups are involved in the crosslinking of the deposited polymer.
  • Table 7 lists the results of combustion analysis for the oligomeric material with the balance of atoms being silicon and oxygen that can not be measured by combustion analysis. This data confirms that based on two independent analysis runs that the process deposits material from run to run that are very similar from an elemental composition point of view. Table 7A - Silicon-29 NMR chemical shift values (relative to TMS at 0.00 ppm) and carbon-hydrogennitrogen combustion analysis data for STAR oligomer
  • STAR oligomer range 5-10 ppm with main signal at 7.15 ppm, broad signal from 0-5 ppm (small), -20 to -23 ppm small broad signal with spikes at -20.99 and -21.67 ppm
  • the purpose of grafting a surface is to implant an amino group or other nucleophile such that an electrophilic tether can be attached for the purpose of binding a biomolecule or other compounds.
  • HPEO polyoxyethylene bis-(N-hydroxybenzotriazolyl) carbonate
  • the residue was reacted with 95% carbon-13 enriched HPEO in dichloromethane.
  • the product obtained was characterized by both infrared spectroscopy and nuclear magnetic resonance spectroscopy.
  • Figures 21A to 21G depict the carbon-13 spectral data for the product confirming urethane bond formation.
  • the infrared spectrum reveals little since the carbon-13 enrichment results in an isotopic shift of the urethane carbonyl.
  • Reaction of natural abundance carbon-13 HPEO reveals the presence of an urethane carbonyl in the 1715-1720 cm -1 range.
  • the proton and carbon NMR confirmed clearly the presence of urethane bonding.
  • the proton NMR spectra reveals a multiplet centered at 4.21 ppm which is characteristic of the methylene protons on the PEG backbone that are located alpha to the urethane oxygen.
  • the carbon-13 NMR ( Figures 21A to 21G) reveals carbonyl carbon signals located at 156.4 and 155.0 ppm confirming the formation of an urethane bond. Model reactions for urethane bond formation show that typically urethane bonds show up in the 155-157 ppm region.
  • the silicon-29 NMR shows no real change in the types of silicon present in the product .
  • optimal conditions for N-trimethylsilylallylamine (TMSAA) plasma grafting as described above.
  • optimal conditions is meant to be conditions which produce “nitrogen” on the treated surface having the following characteristics: (1) stability in water, i.e., to minimize the amount of nitrogen lost on exposure to water; (2) capability of covalent binding to electrophilic PEO molecules, i.e., maximize primary and secondary amines; (3) maintenance of gas permeability of substrate; i.e., minimize gas permeability degradation which may result from the plasma grafting process; and (4) reproducibility of atomic percent nitrogen as monitored by ESCA analysis.
  • Polypropylene hollow fibers Denes, F. ; Percec, V.;

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Abstract

L'invention concerne des procédés et des composés de greffage au plasma. Elle concerne plus particulièrement un nouveau composé utilisé pour le greffage au plasma permettant d'obtenir une surface convenant à l'immobilisation de substances bioactives.
PCT/US1995/011253 1994-09-09 1995-09-08 Procedes et composes de greffage au plasma WO1996008211A2 (fr)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0806250A3 (fr) * 1996-05-10 2002-07-17 Roche Diagnostics GmbH Surfaces revêtues avec des groupes amines
DE102005041330A1 (de) * 2005-08-29 2007-03-01 Silcos Gmbh Silikonelastomere und deren Oberflächenmodifikationen mittels Plasmaverfahren zwecks Beschichtung
WO2008141809A1 (fr) * 2007-05-22 2008-11-27 Fachhochschule Hildesheim/Holzminden/Göttingen Procédé et dispositif pour traiter de manière combinée une surface comprenant un plasma et un rayonnement électromagnétique
WO2011119865A1 (fr) * 2010-03-25 2011-09-29 Tyco Healthcare Group Lp Nœuds chimiques pour sutures
WO2014074560A1 (fr) * 2012-11-06 2014-05-15 Dow Corning Corporation Procédé de fabrication d'une membrane de silicone
CN115554992A (zh) * 2021-06-30 2023-01-03 同济大学 一种聚合物修饰的磁性纳米材料、其制备方法及应用

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5080924A (en) * 1989-04-24 1992-01-14 Drexel University Method of making biocompatible, surface modified materials
US5326584A (en) * 1989-04-24 1994-07-05 Drexel University Biocompatible, surface modified materials and method of making the same
DE69125828T2 (de) * 1991-05-21 1997-07-31 Hewlett Packard Gmbh Verfahren zur Vorbehandlung der Oberfläche eines medizinischen Artikels
US5463010A (en) * 1993-11-12 1995-10-31 Surface Engineering Technologies, Division Of Innerdyne, Inc. Hydrocyclosiloxane membrane prepared by plasma polymerization process

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0806250A3 (fr) * 1996-05-10 2002-07-17 Roche Diagnostics GmbH Surfaces revêtues avec des groupes amines
DE102005041330A1 (de) * 2005-08-29 2007-03-01 Silcos Gmbh Silikonelastomere und deren Oberflächenmodifikationen mittels Plasmaverfahren zwecks Beschichtung
DE102005041330B4 (de) * 2005-08-29 2008-12-18 Silcos Gmbh Silikonelastomere und deren Oberflächenmodifikation mittels Plasmaverfahren zwecks Beschichtung
WO2008141809A1 (fr) * 2007-05-22 2008-11-27 Fachhochschule Hildesheim/Holzminden/Göttingen Procédé et dispositif pour traiter de manière combinée une surface comprenant un plasma et un rayonnement électromagnétique
WO2011119865A1 (fr) * 2010-03-25 2011-09-29 Tyco Healthcare Group Lp Nœuds chimiques pour sutures
WO2014074560A1 (fr) * 2012-11-06 2014-05-15 Dow Corning Corporation Procédé de fabrication d'une membrane de silicone
CN115554992A (zh) * 2021-06-30 2023-01-03 同济大学 一种聚合物修饰的磁性纳米材料、其制备方法及应用
CN115554992B (zh) * 2021-06-30 2023-10-27 同济大学 一种聚合物修饰的磁性纳米材料、其制备方法及应用

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