Patent Application
20070259114
The present invention generally relates to partially coated workpieces and methods and systems for partially coating a workpiece with a coating or other treatment. More specifically, the present invention relates to workpieces, such as implantable medical devices, and methods and systems for coating these medical devices, wherein a treatment or other coating is applied to some but not all surfaces of the workpiece during a coating process.
Coating workpieces is an often repeated procedure in contemporary manufacturing. Workpieces may be coated by methods that include tumble coating, spray coating, dip coating, and electrostatic spraying. During each of these procedures coating is applied to the workpiece prior to the workpiece being used for an intended purpose.
When the workpiece is formed partially or completely out of lattice struts or some other open framework, each of the faces of these struts or framework is exposed to the coating and coated during the coating methods listed above. By exposing each face of the workpiece to the coating being applied, each exposed face will be covered during the coating process.
When the workpiece being coated is an implantable medical device, such as a stent, all faces of the struts that comprise the stent are coated when using the coating systems identified above. For example, when dip coating is used, each face of the stent struts will be exposed to the coating. This coating will remain when the stent is removed from the dip and will dry on each face of the struts. Coating may also remain in the spaces between the struts. This phenomenon is sometimes called “webbing.” Here, not only are the individual struts covered, but some or all of the spaces between the struts are spanned by the coating as well.
The present invention is directed to methods, processes, and systems for coating portions of a workpiece as well as to workpieces that have themselves been coated in accord with the invention. In accord with the invention, for example, some or all outer surfaces of a workpiece, such as a medical implant, may be coated with a therapeutic while inner surfaces of the implant, which are not targeted for coating, may not be coated.
Under methods and processes of the invention, a workpiece may be rotated as it is being coated to drive coating away from non-target surfaces of the workpiece. In other words, as a workpiece, such as a stent is coated, it may be spun such that surfaces of the stent that initially receive coating while the coating is applied, may not longer be coated once the coating is dried because the coating is removed from non-target areas of the stent by forces created from the rotation of the stent. In some embodiments, surfaces of the workpiece may be pre-treated, may have different degrees of smoothness or may be both pre-treated and have different degrees of smoothness. Still further, the workpiece may also be positioned in a treatment chamber during portions or all of the treating and coating process. As noted, the workpiece may be an implantable medical device and the coating may include therapeutic, the workpiece may be other devices as well.
The invention may be embodied in numerous devices and through numerous methods and systems. The following detailed description, which, when taken in conjunction with the annexed drawings, discloses examples of the invention. Other embodiments, which incorporate some or all of the features as taught herein, are also possible.
Referring to the drawings, which form a part of this disclosure:
a shows a workpiece holder connected to a motor shaft that may be employed in accord with the present invention;
b shows a workpiece positioned on the holder of
a is a cross-sectional view of a portion of a coated strut from a medical device that has been coated in accord with the present invention;
b is a cross-sectional view showing the coated strut of
c is a side-view of an arterial stent, which is a medical device that may be coated in accord with the present invention;
a shows an electroplating process that may be employed in accord with the present invention;
b is an end-view of a portion of a coated strut from a medical device that has been pre-treated in accord with the present invention;
c shows a workpiece being sandblasted in accord with the present invention;
d is another end-view of a portion of a coated strut from a medical device that has been pre-treated in accord with the present invention;
e shows a workpiece being spray coated with a polymer adhesion promoter in accord with the present invention;
f is still another end-view of a portion of a coated strut from a medical device that has been pre-treated in accord with the present invention;
a shows a spray coating nozzle and motor as may be employed to coat a workpiece in accord with the invention;
b shows a dispensing nozzle and motor as may be employed to coat a workpiece in accord with the present invention;
a is a side-view in partial cross-section of a motor and a workpiece positioned in a treatment chamber as may be employed to coat the workpiece in accord with the present invention;
b is a side-view, in partial cross-section, of the motor and treatment chamber of
The present invention regards coating one or more surfaces of a workpiece while not coating other surfaces of the workpiece. In some embodiments this may include coating the outside or side surfaces of the workpiece while not coating the inside surfaces of the workpiece. By coating in this fashion the amount of coating resident on the workpiece may be reduced in some cases. This can be useful when the amount of coating resident on the workpiece is metered or is otherwise of interest. For example, if the workpiece is a stent and the coating contains therapeutic a reduction in coating may allow the therapeutic to be delivered in a more targeted fashion after the stent is implanted at a target site. The limited use of coating can also conserve coating materials, which themselves may be valuable.
The selective coating of a workpiece may be accomplished in various ways in accord with the present invention. For example, the workpiece may be rotated before the coating dries or otherwise cures. This rotation may act to drive coating away from a non-target surface. The workpiece may be pretreated in accord with the present invention as well. This pretreatment may act to repel or prevent coating from adhering to one or more surfaces of the workpiece. The workpiece may also be pretreated to facilitate the adhesion or attraction of coating to one or more surfaces of the workpiece. Pretreating may include various steps such as polishing, roughening, and applying polymer adhesion promoters.
The workpiece may be positioned in a treatment chamber when practicing the present invention and both compressible and non-compressible fluids may be supplied to the treatment chamber to improve coating distribution on targeted surfaces. In addition to coating target areas, the invention may also be used to retard “webbing” between areas that are coated. There are numerous other benefits of and uses for the present invention.
a is a side-view of a workpiece holder 101 in accord with the present invention. Evident in
In
In other embodiments, which are not shown, the second shaft 109 may contact surfaces of the workpiece in a variety of other ways. For example, the second shaft 109 may not have arms and can be expandable and compressible to fit inside a workpiece. Thus, in a collapsed position, the workpiece may be placed on the shaft and removed and in an expanded position the workpiece may be supported during the coating process. The components of the holder 101 can also be fabricated from various materials including polymeric and metallic materials. Likewise, the components can be any suitable size and/or shape.
The motor 103 may be any machine that converts energy into mechanical energy to impart motion. In this instance, the motor 103 converts electrical energy into mechanical energy to impart rotary motion to the workpiece. In still other examples, which are not shown, the motor 103 may use mechanical energy (e.g., a crank) to impart rotation to the holder 101. The motor shaft 105 may be rotatable clockwise and/or counterclockwise.
b shows the workpiece holder 101 of
a is a side sectional view of a strut of a stent that may be coated in accord with the present invention. The strut 204 in
b shows another example of how a coating may be applied in accord with the invention. In
c is a side view of an implantable aortic stent including a lattice portion 202 that may be coated in accord with the invention. The stent may be porous or have portions thereof that are porous. The struts 204 shown in
Various methods may be employed for delivery and implantation of the stent. For instance, a self-expanding stent may be positioned at the distal end of a catheter around a core lumen.
Self-expanding stents may be typically held in an unexpanded state during delivery using a variety of methods including sheaths or sleeves which cover all or a portion of the stent. When the stent is in its desired location of the targeted vessel the sheath or sleeve is retracted to expose the stent which then self-expands upon retraction.
Another method includes mounting a mechanically expandable stent on an expandable member, such as a dilatation balloon provided on the distal end of an intravascular catheter, advancing the catheter through a patient's vasculature to the desired location within the patient's body lumen, and inflating the balloon on the catheter to expand the stent into a permanent expanded condition.
One method of inflating the balloon includes the use of inflation fluid. The expandable member is then deflated and the catheter removed from the body lumen, leaving the stent in the vessel to hold the vessel open.
While the workpiece 200 shown in these initial figures is a stent, many other workpieces 200 may be coated in accord with the invention. For example, other medical devices that may be coated include filters (e.g., vena cava filters), stent grafts, vascular grafts, intraluminal paving systems, implants and other devices used in connection with drug-loaded polymer coatings. Likewise, the workpeice 200 may not be an implantable medical device but may, instead, be another piece that needs to be coated only on certain pre-selected surfaces. In some instances these medical devices or other workpieces 200 may be made from conductive materials and in other instances they may not be. For example, they may be made from polymers or ceramics.
a is a side-view illustrating the workpiece during a pre-treatment step that may be employed in accord with the present invention. As seen in
The electropolishing pre-treatment process of
As seen in
The pre-treatment step may also be applied with different methods and processes. For example, the workpiece 300 can be roughened during pre-treatment. Roughening the workpiece 300 may increase the “wettability” of the target surface of the workpiece 300. Therefore, the roughened surface may facilitate the coating of a target surface.
As seen in
As described herein, the outer surface 308 may be roughened to increase “wettability.” Therefore, coating of the outer surface 308 may be facilitated. In still other examples, not shown, the workpiece 300 may be roughened with various conventional surface deposition techniques including etching and electroplating.
e shows an example of the workpiece 300 being sprayed with a polymer adhesion promoter 332. A nozzle 334 may be used to direct the polymer adhesion promoter 332 towards the workpiece 300.
f is an end-view showing an outer surface 308 of a strut 304 following the polymer adhesion promoter 332 application. The polymer adhesion promoter 332 also may facilitate the coating of a target surface of the workpiece. In other examples, which are not shown, polymer adhesion promoters 332 may be applied to the workpiece using other applications including etching or electroplating.
The invention may be pre-treated using any of numerous processes and methods. For example, the workpiece 300 may be pre-treated by mechanical abrading and chemical etching processes.
Mechanical abrading may be performed using any abrasive product or material which can either remove a layer, polish, or roughen a surface of a workpiece 300. The abrading process may be done by hand. For example, a non-rotary block or pad may be used. Alternatively, the abrading process may be performed with the assistance of a machine. For instance, a tool using an endless band of abrasive material or a rotary cylinder or disk may be used.
Chemical etching may also be used. Chemical etching involves the use of a chemical etchant to remove a layer, polish, or roughen a surface of a workpiece 300. For example, the workpiece 300 may be immersed in a bath of chemical etchant to polish the workpiece 300. Any etchant may be used including isotropic or anisotropic etchants. The workpiece 300 may also be contacted with ions from a plasma (e.g., nitrogen, chlorine, or boron trichloride) or chemically milled.
a shows another step that may be employed when practicing the invention. This step includes applying a coating 436 to a target surface of the lattice portion 402 of the workpiece 400. In this example, the surface is the outer surface 408 of the lattice portion 402. The coating of the outer surface 408 can be applied to the lattice portion 402 by various methods including, but not limited to, dipping, spraying, rolling, brushing, electrostatic plating or spinning, vapor deposition, air spraying including atomized spray coating, and spray coating using an ultrasonic nozzle.
In the example of
In the example of
As
One parameter that may be varied are the coating solution characteristics. For example, the coating solution viscosity may be important in determining how the coating spreads and deposits on the outer surface 408 and cut faces of the lattice portion 402. In some instances, viscosity can be controlled by varying the elements of the coating 436. For example, some coating 436 includes organic solvents into which a therapeutic may be dissolved. The organic solvent can be varied to control viscosity. In still other instances, the percentage of solids, the addition of biocompatible surfactants, and the release of the therapeutic can vary to control viscosity.
Another parameter that can change is the density of the coating 436. For example, if a coating 436 including therapeutic and polymer were used, the therapeutic may be suspended in the polymer. Therefore, when the denser therapeutic experiences centrifugal force from being rotated, the therapeutic may be forced to the outer surface 408 of the workpiece 400. This results in concentrated therapeutic on the outer surface of the workpiece 400. Therefore, the amount of therapeutic utilized can be minimized.
Still another parameter that may be varied is the speed or revolutions per minute (RPM) of the motor shaft and/or holder. The RPM can be varied to affect the degree of radial centrifugal force applied to the coating 436. Additionally, the velocity and turbulence of the air which surrounds the workpiece 400 can also be controlled. In
Yet still another parameter that can be varied is the duration of time the workpiece 400 is rotated. Spinning duration can affect the thickness and positioning of the coating 436 on the outer surface 408 of the lattice portion 402. For example, in some instances, the spin time may preferably be around five minutes.
a is a side view of a horizontally orientated treatment chamber 642 in accord with an embodiment of the present invention. In this embodiment, the treatment chamber 642 includes an outer wall 644, an inner wall 646, and end plates 648a, 648b. The outer wall 644 may include a fluid passage or passages 650 which may be designed and sized to allow compressible fluids, such as air, nitrogen, carbon dioxide, and other compressible gases, to pass from outside the outer wall 644 to inside the inner wall 646 and into the treatment chamber 642.
The end plates 648a, 648b may include exhaust ports 652, which may be sized and designed to allow compressible fluid entering the treatment chamber to be exhausted from the chamber. At least one of the end plates 648a, 648b, in the instant case 648a, may be rotatably coupled to the treatment chamber 642 so that it may swing away from the treatment chamber to allow a workpiece 600 to be positioned within the treatment chamber. The arrow in
As seen in
As seen in
As indicated above, when one of the end plates 648a is in an open position, a workpiece 600 may be positioned into the treatment chamber 642 and onto the holder 601. Once the workpiece 600 has been placed within the treatment chamber 642, it may then be treated, coated or otherwise interfaced with a therapeutic or other material. In the instant case, the workpiece 600 can be coated prior to or while positioned inside the treatment chamber 642. During or after the workpiece 600 has been interfaced with the coating, compressible fluid may be supplied to and exhausted from the chamber to facilitate drying and/or evaporation of the coating.
Once the workpiece 600 has been treated and removed, another workpiece 600 may be positioned inside the chamber for treatment. This treatment cycle may be repeated as necessary. Alternatively, the treatment chamber 642 may be designed or constructed to be used only a single time and then discarded.
As in the above example, the coating may be injected through the same fluid passages 650 that are injecting the compressible fluid into the treatment chamber. Thus, the fluid passages may be carrying therapeutic, compressible fluids coatings or a combination. Where both therapeutic, coatings or both and compressible fluids are being carried through the same fluid passage the therapeutic or coatings may be mixed with the compressible fluid upstream of the fluid passage 650 or may be atomized at or near the entrance or exit of the fluid passage 650.
In still other embodiments, therapeutic may also be injected via fluid passages that do not contain or are not carrying compressible fluid.
As shown in
In this example, non-compressible fluid 754 is also supplied to the treatment chamber 742. When the workpiece 700 is rotated, the fluid moves toward the outer wall 756 of the treatment chamber 742 to form a boundary around a surface of the workpiece 700. Therefore, the concentration of the coating on a target surface may improve. In
The term “treatment chamber” as used herein may be any vessel having defined walls with inside surfaces. A treatment chamber may be made from various materials including clear, translucent, and opaque polymers, metals, and ceramics. Clear polymers, which provide for the internal viewing of implants being coated or impregnated with therapeutics in the treatment chamber, may be used in an exemplary embodiment.
The treatment chamber may be preferably cylindrical but it may be other shapes as well. These shapes may include octagons, other multi-sided polygons, ovals, and non-symmetrical shapes. Furthermore, the treatment chamber may be sized to hold one or more implants.
In an exemplary embodiment, a treatment chamber may be sized to allow implants to be positioned end to end next to one another but not side by side. In other words, in an exemplary embodiment where both the implants and the treatment chamber are cylindrical, the inside diameter of the treatment chamber may be slightly larger than the outside diameter of the implant to be coated. The flow rate and pressure of the compressible fluid injected into the treatment chamber and the size and placement of the fluid passages may be adjusted to accommodate the size, shape, and weight of the implant to be coated. It may also be adjusted depending upon the compressible fluid being used and the pressure developed within the coating chamber. The size and placement of the exhaust ports may also affect the flow rate and pressure of the compressible fluid being used. Still further, the implants may be loaded into the chamber in various orientations, e.g., forward, backward, open, and closed (in the case of an expandable implant).
While various embodiments have been described, other embodiments are plausible. It should be understood that the foregoing descriptions of various examples of the rotating member and treatment chamber are not intended to be limiting, and any number of modifications, combinations, and alternatives of the examples may be employed to facilitate the effectiveness of the coating of target surfaces of the workpiece.
The coating, in accord with the embodiments of the present invention, may comprise a polymeric and or therapeutic agent formed, for example, by admixing a drug agent with a liquid polymer, in the absence of a solvent, to form a liquid polymer/drug agent mixture. A suitable list of drugs and/or polymer combinations is listed below. The term “therapeutic agent” as used herein includes one or more “therapeutic agents” or “drugs.” The terms “therapeutic agents” or “drugs ” can be used interchangeably herein and include pharmaceutically active compounds, nucleic acids with and without carrier vectors such as lipids, compacting agents (such as histones), viruses (such as adenovirus, andenoassociated virus, retrovirus, lentivirus and α-virus), polymers, hyaluronic acid, proteins, cells and the like, with or without targeting sequences.
Specific examples of therapeutic agents used in conjunction with the present invention include, for example, pharmaceutically active compounds, proteins, cells, oligonucleotides, ribozymes, anti-sense oligonucleotides, DNA compacting agents, gene/vector systems (i.e., any vehicle that allows for the uptake and expression of nucleic acids), nucleic acids (including, for example, recombinant nucleic acids; naked DNA, cDNA, RNA; genomic DNA, cDNA or RNA in a non-infectious vector or in a viral vector and which further may have attached peptide targeting sequences; antisense nucleic acid (RNA or DNA); and DNA chimeras which include gene sequences and encoding for ferry proteins such as membrane translocating sequences (“MTS”) and herpes simplex virus-1 (“VP22”)), and viral, liposomes and cationic and anionic polymers and neutral polymers that are selected from a number of types depending on the desired application. Non-limiting examples of virus vectors or vectors derived from viral sources include adenoviral vectors, herpes simplex vectors, papilloma vectors, adeno-associated vectors, retroviral vectors, and the like. Non-limiting examples of biologically active solutes include anti-thrombogenic agents such as heparin, heparin derivatives, urokinase, and PPACK (dextrophenylalanine proline arginine chloromethylketone); antioxidants such as probucol and retinoic acid; angiogenic and anti-angiogenic agents and factors; anti-proliferative agents such as enoxaprin, angiopeptin, rapamycin, angiopeptin, monoclonal antibodies capable of blocking smooth muscle cell proliferation, hirudin, and acetylsalicylic acid; anti-inflammatory agents such as dexamethasone, prednisolone, corticosterone, budesonide, estrogen, sulfasalazine, acetyl salicylic acid, and mesalamine; calcium entry blockers such as verapamil, diltiazem and nifedipine; antineoplastic/antiproliferative/anti-mitotic agents such as paclitaxel, 5-fluorouracil, methotrexate, doxorubicin, daunorubicin, cyclosporine, cisplatin, vinblastine, vincristine, epothilones, endostatin, angiostatin and thymidine kinase inhibitors; antimicrobials such as triclosan, cephalosporins, aminoglycosides, and nitrofurantoin; anesthetic agents such as lidocaine, bupivacaine, and ropivacaine; nitric oxide (NO) donors such as linsidomine, molsidomine, L-arginine, NO-protein adducts, NO-carbohydrate adducts, polymeric or oligomeric NO adducts; anti-coagulants such as D-Phe-Pro-Arg chloromethyl ketone, an RGD peptide-containing compound, heparin, antithrombin compounds, platelet receptor antagonists, anti-thrombin antibodies, anti-platelet receptor antibodies, enoxaparin, hirudin, Warfarin sodium, Dicumarol, aspirin, prostaglandin inhibitors, platelet inhibitors and tick antiplatelet factors; vascular cell growth promotors such as growth factors, growth factor receptor antagonists, transcriptional activators, and translational promotors; vascular cell growth inhibitors such as growth factor inhibitors, growth factor receptor antagonists, transcriptional repressors, translational repressors, replication inhibitors, inhibitory antibodies, antibodies directed against growth factors, bifunctional molecules consisting of a growth factor and a cytotoxin, bifunctional molecules consisting of an antibody and a cytotoxin; cholesterol-lowering agents; vasodilating agents; agents which interfere with endogenous vascoactive mechanisms; survival genes which protect against cell death, such as anti-apoptotic Bcl-2 family factors and Akt kinase; and combinations thereof. Cells can be of human origin (autologous or allogenic) or from an animal source (xenogeneic), genetically engineered if desired to deliver proteins of interest at the insertion site. Any modifications are routinely made by one skilled in the art.
Polynucleotide sequences useful in practice of the invention include DNA or RNA sequences having a therapeutic effect after being taken up by a cell. Examples of therapeutic polynucleotides include anti-sense DNA and RNA; DNA coding for an anti-sense RNA; or DNA coding for tRNA or rRNA to replace defective or deficient endogenous molecules. The polynucleotides can also code for therapeutic proteins or polypeptides. A polypeptide is understood to be any translation product of a polynucleotide regardless of size, and whether glycosylated or not. Therapeutic proteins and polypeptides include as a primary example, those proteins or polypeptides that can compensate for defective or deficient species in an animal, or those that act through toxic effects to limit or remove harmful cells from the body. In addition, the polypeptides or proteins that can be injected, or whose DNA can be incorporated, include without limitation, angiogenic factors and other molecules competent to induce angiogenesis, including acidic and basic fibroblast growth factors, vascular endothelial growth factor, hif-1, epidermal growth factor, transforming growth factor ∀ and ∃, platelet-derived endothelial growth factor, platelet-derived growth factor, tumor necrosis factor ∀, hepatocyte growth factor and insulin like growth factor; growth factors; cell cycle inhibitors including CDK inhibitors; anti-restenosis agents, including p15, p16, p18, p19, p21, p27, p53, p57, Rb, nFkB and E2F decoys, thymidine kinase (“TK”) and combinations thereof and other agents useful for interfering with cell proliferation, including agents for treating malignancies; and combinations thereof. Still other useful factors, which can be provided as polypeptides or as DNA encoding these polypeptides, include monocyte chemoattractant protein (“MCP-1”), and the family of bone morphogenic proteins (“BMP's”). The known proteins include BMP-2, BMP-3, BMP-4, BMP-5, BMP-6 (Vgr-1), BMP-7 (OP-1), BMP-8, BMP-9, BMP-10, BMP-11, BMP-12, BMP-13, BMP-14, BMP-15, and BMP-16. Currently preferred BMP's are any of BMP-2,BMP-3,BMP-4, BMP-5, BMP-6 and BMP-7. These dimeric proteins can be provided as homodimers, heterodimers, or combinations thereof, alone or together with other molecules. Alternatively or, in addition, molecules capable of inducing an upstream or downstream effect of a BMP can be provided. Such molecules include any of the “hedgehog” proteins, or the DNA's encoding them.
As stated above, coatings used with the exemplary embodiments of the present invention may comprise a polymeric material/drug agent matrix formed, for example, by admixing a drug agent with a liquid polymer, in the absence of a solvent, to form a liquid polymer/drug agent mixture. Curing of the mixture typically occurs in-situ. To facilitate curing, a cross-linking or curing agent may be added to the mixture prior to application thereof. Addition of the cross-linking or curing agent to the polymer/drug agent liquid mixture must not occur too far in advance of the application of the mixture in order to avoid over-curing of the mixture prior to application thereof. Curing may also occur in-situ by exposing the polymer/drug agent mixture, after application to the luminal surface, to radiation such as ultraviolet radiation or laser light, heat, or by contact with metabolic fluids such as water at the site where the mixture has been applied to the luminal surface. In coating systems employed in conjunction with the present invention, the polymeric material may be either bioabsorbable or biostable. Any of the polymers described herein that may be formulated as a liquid may be used to form the polymer/drug agent mixture.
The polymer used in the exemplary embodiments of the present invention is preferably capable of absorbing a substantial amount of drug solution. When applied as a coating on a medical device in accordance with the present invention, the dry polymer is typically on the order of from about 1 to about 50 microns thick. In the case of a balloon catheter, the thickness is preferably about 1 to 10 microns thick, and more preferably about 2 to 5 microns. Very thin polymer coatings, e.g., of about 0.2-0.3 microns and much thicker coatings, e.g., more than 10 microns, are also possible. It is also within the scope of the present invention to apply multiple layers of polymer coating onto a medical device. Such multiple layers are of the same or different polymer materials.
The polymer of the present invention may be hydrophilic or hydrophobic, and may be selected from the group consisting of polycarboxylic acids, cellulosic polymers, including cellulose acetate and cellulose nitrate, gelatin, polyvinylpyrrolidone, cross-linked polyvinylpyrrolidone, polyanhydrides including maleic anhydride polymers, polyamides, polyvinyl alcohols, copolymers of vinyl monomers such as EVA, polyvinyl ethers, polyvinyl aromatics, polyethylene oxides, glycosaminoglycans, polysaccharides, polyesters including polyethylene terephthalate, polyacrylamides, polyethers, polyether sulfone, polycarbonate, polyalkylenes including polypropylene, polyethylene and high molecular weight polyethylene, halogenated polyalkylenes including polytetrafluoroethylene, polyurethanes, polyorthoesters, proteins, polypeptides, silicones, siloxane polymers, polylactic acid, polyglycolic acid, polycaprolactone, polyhydroxybutyrate valerate and blends and copolymers thereof as well as other biodegradable, bioabsorbable and biostable polymers and copolymers.
Coatings from polymer dispersions such as polyurethane dispersions (BAYHDROL®, etc.) and acrylic latex dispersions are also within the scope of the present invention. The polymer may be a protein polymer, fibrin, collagen and derivatives thereof, polysaccharides such as celluloses, starches, dextrans, alginates and derivatives of these polysaccharides, an extracellular matrix component, hyaluronic acid, or another biologic agent or a suitable mixture of any of these, for example. In one embodiment of the invention, the preferred polymer is polyacrylic acid, available as HYDROPLUS® (Boston Scientific Corporation, Natick, Mass.), and described in U.S. Pat. No. 5,091,205, the disclosure of which is hereby incorporated herein by reference. U.S. Pat. No. 5,091,205 describes medical devices coated with one or more polyisocyanates such that the devices become instantly lubricious when exposed to body fluids. In another preferred embodiment of the invention, the polymer is a copolymer of polylactic acid and polycaprolactone.
The examples described herein are merely illustrative, as numerous other embodiments may be implemented without departing from the spirit and scope of the exemplary embodiments of the present invention. Moreover, while certain features of the invention may be shown on only certain embodiments or configurations, these features may be exchanged, added, and removed from and between the various embodiments or configurations while remaining within the scope of the invention. Likewise, methods described and disclosed may also be performed in various sequences, with some or all of the disclosed steps being performed in a different order than described while still remaining within the spirit and scope of the present invention.
