A MEDICAL TUBULAR DEVICE

Abstract

The invention relates to medical devices and production thereof. The medical device may be a tubular medical device and has a high biocompatibility e.g. for use as implant. The medical tubular device may have a body structure extending from a first end to a second end of the medical tubular device and having a luminal surface and an external surface, wherein the body structure comprises an interpenetrating polymer network (IPN) comprising a host polymer matrix and at least one hydrogel guest polymer domain of a guest polymer, which is interpenetrating the host polymer matrix.

Claims

1-134. (canceled)

135. A medical tubular device comprising a body structure extending from a first end to a second end of the medical tubular device and having a luminal surface and an external surface, wherein said body structure comprises an interpenetrating polymer network (IPN) comprising a host polymer matrix and at least one hydrogel guest polymer domain of a guest polymer comprising a plurality of interconnected paths of the guest polymer, which is interpenetrating the host polymer matrix, said at least one hydrogel polymer domain comprises a luminal surface guest polymer domain comprising at least a part of the luminal surface, wherein a plurality of the paths of the guest polymer coincide and form at least a part of said luminal surface and wherein said luminal surface comprises zwitterionic moieties, said zwitterionic moieties being covalently bonded to said guest polymer.

136. The tubular device of claim 135, wherein said guest polymer comprises a zwitterionic hydrogel comprising a cross-linked network of polymerized monomers comprising of one or more type of monomers.

137. The tubular device of claim 135, wherein the zwitterionic monomers comprises at least one of sulfobetanies, carbobetaines, phosphobetaines, phosphocholines or any combinations thereof.

138. The tubular device of claim 135, wherein the external surface comprises a surface at least partly of said guest polymer, wherein a plurality of the paths of the guest polymer coincide and form at least a part of said external surface, and wherein said external surface comprises zwitterionic moieties, said zwitterionic moieties being covalently bonded to said hydrogel (guest) polymer.

139. The tubular device of claim 135, wherein the luminal surface comprises at least one covalent bonded drug, wherein the covalently bonded drug comprises a thrombosis deactivating drug(s).

140. The tubular device of claim 135, wherein said body structure comprises a releasable drug selected from an anti-proliferative drug releasable at least via said luminal surface or an anti-infective drug releasable via at least said external surface.

141. The tubular device of claim 140, wherein the anti-proliferative drug comprises paclitaxel (Taxol) and/or rapamycin and the anti-infective drug comprises rifampicin and/or minocycline.

142. The tubular device of claim 135, wherein the host polymer comprises a cross-linked elastomer.

143. The tubular device of claim 135, wherein the host polymer has a shore A hardness of from about 15 to about 70, a tear strength of at least about 25 kN/m and a stress at 200% elongation of at least about 0.3 MPa.

144. The tubular device of claim 135, wherein the guest polymer is cross-linked, and is polymerized from monomers comprising at least one zwitterion and at least one of PHEMA, PEGMEA or vinylimidazole butyl sulfonate.

145. The tubular device of claim 135, wherein the hydrogel guest polymer comprises a copolymer polymerized from monomers comprising at least one zwitterionic monomer, selected from a sulfobetaine, a carbobetaine, a phosphobetaine, or a phosphocholine.

146. The tubular device of claim 135, wherein the hydrogel guest polymer comprises a copolymer polymerised from monomers comprising a photoactive monomer.

147. The tubular device of claim 135, wherein the at least one guest polymer domain comprises a clot promoting domain and/or a cell proliferation promoting domain located at the external surface of the body structure and/or located at an intermediate guest polymer domain, which does not comprise the luminal surface or the external surface.

148. The tubular device of claim 135, wherein the host polymer comprises two or more guest polymer domains, wherein the two or more guest polymer domains comprises a luminal surface guest polymer domain comprising at least a part of the luminal surface and an external surface guest polymer domain comprising at least a part of the external surface, wherein the two or more guest polymer domains are separated by a polymer portion essentially free of guest polymer.

149. The tubular device of claim 135, wherein the body structure is a layered body structure comprising two or more layers, wherein at least one of said layers comprises or consist of the IPN.

150. The tubular device of claim 149, wherein at least one layer of the body structure is a polymer layer without an IPN, selected from a polymer layer comprising or consisting of polytetrafluoroethylene (PTFE), expanded PTFE, polyethylene terephthalate (PET), polyurethane (PU) and/or silicone elastomer.

151. The tubular device of claim 135, wherein the tubular device comprises a tubular support structure located concentrically with the body structure, wherein the support structure comprises a helical wire and/or a cuff close-fitting to the external surface of the body structure and wherein the support structure being of a polymer material comprising collagen, nylon, poly(lactic-co-glycolic acid) (PLGA), polytetrafluoroethylene (PTFE), expanded PTFE polyethylene terephthalate (PET), polyurethane (PU) and/or silicone elastomer.

152. The tubular device of claim 151, wherein the cuff comprises an IPN material loaded with one or more drugs selected from growth hormone, antifibrinolytic drug(s), clot promoting drug(s) and/or cell proliferation promoting drug(s).

153. The tubular device of claim 135, wherein the body structure has an internal diameter of from about 2 mm to about 6 cm, a compliance of from about 1 to about 10.

154. The tubular device of claim 135, wherein the medical tubular device is an implantable tubular device selected from a dialysis graft, a stent, a vascular graft, a stentgraft or a Thoraflex hybrid device.

155. The tubular device of claim 135, wherein the medical tubular device is a dialysis tube, a feeding tube, a venous catheter, or a peripherally inserted central venous catheter (PICC line).

156. The tubular device of claim 136, wherein the at least one zwitterionic monomer is selected from zwitterionic monomer with formula I-XIII ##STR00030## ##STR00031##

157. A zwitterionic monomer selected from zwitterionic monomer with formula I-XIII ##STR00032## ##STR00033##

Description

BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS AND ELEMENTS OF THE INVENTION

[0316] The above and/or additional objects, features and advantages of the present invention will be further elucidated by the following illustrative and non-limiting description of embodiments and examples of the present invention, with reference to the appended drawings.

[0317] The figures are schematic and are not drawn to scale and may be simplified for clarity. Throughout, the same reference numerals are used for identical or corresponding parts.

[0318] FIGS. 1a and 1b are side views of examples of a medical tubular device of the invention.

[0319] FIGS. 2a-2d are side views of further examples of a medical tubular device of the invention.

[0320] FIGS. 3a-3c are side cross-sectional views of sections of body structure of examples of medical tubular devices of the invention. The sectional views are seen in cuts along the length of the body structures.

[0321] FIG. 4 illustrates a setup for simultaneous treatment, e.g. loading and/or reacting of a luminal surface guest polymer domain and an external surface guest polymer domain of a medical tubular device of an embodiment of the invention.

[0322] FIG. 5 show examples of anions and cations, which may form part of the zwitterionic moieties of a zwitterionic hydrogel of a medical tubular device of an embodiment of the invention.

[0323] FIG. 6 show examples monomers, which may be used for the guest polymer domain of a medical tubular device of an embodiment of the invention.

[0324] FIG. 7 show the spiropyran in its “spiro form” where it is substantially color-less and the spiropyran in its “merocyanine form” where it is purple.

[0325] FIGS. 8a and 8b show samples of medical tubular devices containing spiropyran in a first condition (after exposure to visual light) and a second condition (after exposure to UV light) respectively.

[0326] FIGS. 9a and 9b are curves showing the force required to remove samples with and without chitosan respectively, from a surface covered with an epithelial layer.

[0327] FIG. 10 shows the back of a pig used to evaluate the risk of infection of the tubular medical device. Six pieces of medical tubular device loaded with a combination of minocycline and rifampicin are implanted on one side of the back. Six pieces of commercial state-of-the-art vascular graft (Propaten CBAS heparin coated, Gore) is implanted on the other side. All pieces are challenged with a load of bacteria. After two weeks, the implants are collected and the level of infection is determined/evaluated.

[0328] FIG. 11a and 11b shows the implanted site after reopening after 14 days for the new medical tubular device and Gore's propaten CBAS heparin coated graft respectively.

[0329] FIG. 12 shows the quantification of biofilm bacteria (S. aureus ATCC 29213) on IPN and Gore's propaten CBAS heparin coated graft materials (left) and in the surrounding subcutaneous tissue near the implanted materials (right).

[0330] FIG. 13 shows the quantification of biofilm bacteria (S. aureus ATCC 29213) in IPN and Gore's propaten CBAS heparin coated graft material as function of bacteria challenge.

[0331] FIG. 14 shows the analysis of functional Taxol release from the new tubular medical device loaded with Taxol. Graph indicates cell proliferation (EA.hy926 endothelial cell culture) after exposure to release media from 10 mm sections of Taxol-loaded IPN grafts (•) or unloaded IPN controls (.square-solid.). After 21 weeks, grafts still exhibit release of Taxol at levels that completely inhibits endothelial cell growth.

[0332] FIGS. 15a and 15b show the explant of Gore's propaten CBAS Heparin vascular graft and new medical tubular device, respectively, after implanted as a vascular bypass graft in the carotid artery of sheep for 6 months.

[0333] FIG. 16 shows a methacrylic monomer with a protecting group protecting a functional moiety, the protecting group is preferably fluorenylmethyloxycarbonyl (FMOC) and/or the protected functional moiety preferably comprises a —NH.sub.2 group.

[0334] FIG. 1a illustrates an embodiment of a linear medical tubular device 1, which is suitable for use as a vascular graft. The medical tubular device consists in this embodiment of the body structure 1 and has one single lumen.

[0335] FIG. 1b illustrates another embodiment of a branched (bifurcated) medical tubular device, which is suitable for use as a vascular graft. The branched medical tubular device comprises a first part 2a with a first lumen and branched parts 2b and 2c branching the lumen into two lumens.

[0336] In practice, the medical tubular device may have any desired number of branches. Preferably, the medical tubular device is a non-branched medical tubular device.

[0337] FIG. 2a show a medical tubular device with a body structure having small anchor points 3 e.g. provided by small deformations in the external surface and/or by cilias shaped brushes of hydrogel (guest) polymer.

[0338] FIG. 2b show a medical tubular device with a body structure 4b having cuffs 4a arranged at its external surface at each end of the body structure 4b. The cuffs may e.g. be as described above and may for example have the function of reinforcing the body structure e.g. for suturing.

[0339] FIG. 2c show a medical tubular device with a body structure with a support net and/or a chitosan coating 5 onto its external surface.

[0340] FIG. 2d show a medical tubular device with a helically support structure 6a applied onto the external surface 6b of the body structure.

[0341] FIG. 3a illustrates a body structure with a luminal surface guest polymer domain 7a and an external surface guest polymer domain 7b, where the luminal surface guest polymer domain 7a and the external surface guest polymer domain 7b are separated by a (intermediate) layer 7c of the host polymer without any guest polymer.

[0342] FIG. 3b illustrates a body structure with a luminal surface guest polymer domain 8a, an intermediate guest polymer domain 8b and an external surface guest polymer domain 8c, where the guest polymer domains 8a, 8b, 8c are separated by layers 8d, 8e of host polymer without any guest polymer.

[0343] FIG. 3c illustrates a body structure with a layered structure comprising an IPN layer 10 and a further, non-IPN layer 9, such as a PTFE layer. As explained above the body structure of embodiments of the invention may have several further layers, such as 2, 3, 4 or 5.

[0344] The setup shown in FIG. 4 comprises a first container 11 with a first treatment fluid (for treating the luminal guest polymer), a second container 12 with a second treatment fluid (for treating the external guest polymer) and a peristaltic pump 17.

[0345] A medical tubular device 15 of an embodiment of the invention is provided to have a luminal surface guest polymer domain and an external surface guest polymer domain e.g. as described elsewhere herein.

[0346] The medical tubular device is mounted to a first hose section 13a and a second hose section 13b via connecting studs 16 and hose clamps 14. The free end 13a′ of the first hose section 13a is submerged into the first treatment fluid of the first container 11 and the free end 13b′ of the second hose section is arranged to have outlet in the first container 11.

[0347] The first hose section 13a is connected to the peristaltic pump 17 to ensure that the first treatment fluid is pumped continuously or in steps from the first container 11, via the first hose section 13a and through the lumen of the medical tubular device 15 and further the treatment fluid is returned to the first container 11 via the section hose section 13b. The peristaltic pump 17 could naturally instead have been connected to the second hose section 13b′.

[0348] In a variation thereof, the first treatment fluid may be held steady within the tube for the treatment time.

[0349] At the same time, the medical tubular device 15 is submerged in the second treatment fluid of the second container 12.

[0350] The first and the second treatment fluids (11 and 12) are advantageously different from each other. The first and the second treatment fluids (11 and 12) may independently from each other be selected from a loading fluid comprising at least one loading drug for loading the respective guest polymer domains and a reaction fluid comprising at least one reagent adapted for treating the guest polymer, e.g. to chemically bind a drug to the guest polymer.

[0351] In an embodiment, the first treatment fluid (11) is a loading drug and the second treatment fluid (12) is a reaction fluid. In an embodiment, the first treatment fluid (11) is a reaction fluid and the second treatment fluid (12) is a loading drug. The drug(s) may be as described elsewhere herein.

[0352] In an embodiment, the first treatment fluid (11) is a loading fluid comprising Taxol for being loaded into the luminal surface guest polymer domain, e.g. to provide a gradient of Taxol concentration in the luminal surface guest polymer domain. In this or in another embodiment the second treatment fluid (12) is a loading fluid for loading anti-infective drug such as Rifampicin and/or minocycline.

[0353] The examples of anions and cations of FIG. 5 are head moieties, which may be modified and/or combined to form a desired zwitterionic moiety and/or monomer.

[0354] The monomers shown in FIG. 6 comprises the zwitterionic monomers sulfobetanies, carbobetaines and phosphobetaines which may advantageously be applied for providing one or more guest polymer domain(s) and/or guest polymer surfaces of the medical tubular device.

[0355] The zwitterionic monomers are synthesized from respectively vinylimidazole, metacrylamides and methacrylate ester.

EXAMPLES

Example 1a—Synthesis of Spiropyran-OH

[0356] Synthesis of SP—OH was done in three steps (FIG. 7a), for each of the steps a HNMR examination was performed to confirm the structure. The analyze of HNMR spectrum was done by Bruker software. For each of the three steps, the HNMR of the samples shows all expected signals.

Step 1: Synthesis of 1-)2-hydroxyethyl(-2,3,3-trimethyl-3H-indolium bromide (1 of FIG. 7a)

[0357] A solution of 2,3,3-trimethyl-3H-indol (2.61 g, 16 mmol) and 2-bromoethanol (2.46 g, 20 mmol) in MeCN (20 mL) was heated for 24 h under reflux and N.sub.2. After cooling down to ambient temperature, the solvent was distilled off under reduced pressure. The residue was suspended in hexane (25 mL) and the mixture was sonicated and filtered. The resulting solid was crystallized from CHCl.sub.3 (35 mL) to afford 1 (2.95 g, 69%) as a pink solid. The crystals were characterized with HNMR.

Step 2: Synthesis of 9,9,9a-Trimethyl-2,3,9,9a-tetrahydro-oxazolo[3,2-a]indole (2 of FIG. 7a)

[0358] A solution of the compound of step 1 (2.93 g, 10 mmol) and KOH (0.92 g, 16 mmol) in H.sub.2O (50 mL) was stirred at ambient temperature for 10 min and then it was extracted with Et.sub.2O (3*20 mL). The organic phase was concentrated under reduced pressure to afford 2 (1.84 g, 88%) as a yellow oil and it was characterized with HNMR.

Step 3: Synthesis of 2-(3,3′-dimethyl-6-nitro-3′H-spiro[chromene-2,2′-indol]-1′-yl) ethanol (SP—OH) (3 of FIG. 7a)

[0359] A solution of 2-hydroxy-5-nitrobenzaldehyde (1.05 g, 6 mmol) and the compound of step 2 (0.87 g, 4 mmol) in EtOH (10 mL) was heated for 3 h under reflux and N.sub.2. After cooling down to ambient temperature, the mixture was filtered. The resulting solid was washed with EtOH (2 mL) and dried to afford SP—OH (1.22 g, 81%) as a purple solid and it was characterized by HNMR.

Example 1b—Synthesis of Spiropyran Monomer (SPMA)

[0360] The photoactive compound. SP is a photoactive compound which isomerizes from the hydrophobic (neutral) spiropyran state (so called closed form) to the hydrophilic (zwitterionic) merocyanine state (so called open form) under blue light irradiation (FIG. 7). As can be seen, the hydrophobic state (SP) is transparent while the hydrophilic state (MC) is purple. The photoisomerization of the SP is totally reversible and the hydrophilicity of the two isomers is significantly different.

[0361] FIG. 7 show the spiropyran in its “spiro form” where it is substantially color-less in visible light and the spiropyran in its “merocyanine form” where it is dark purple.

[0362] The “merocyanine form” is hydrophilic, due to the generation of a zwitterion. The transformation between the “spiro form” and the “merocyanine form” is reversible and occurs by exposing the material to UV light and visible light respectively. This generates a hydrophilicity switch, where the materials hydrophilicity may be changed depending on the wavelength of the light that hits the material. Hydrophilicity switches may be utilized to trigger drug delivery, and/or attach/detach to cells.

[0363] The figure illustrates that the spiropyran can be switched from its spiro form to its merocyanine form by subjecting it to UV illumination e.g. at about 365 nm. After UV illumination, the spiropyran may slowly return from its merocyanine form to its spiro form or upon illumination with visible light, the returning to the spiro form may be faster.

[0364] The transfer between spiropyran and merocyanine form may also be induced by other impacts, like pH and/or mechanically.

Example 2—Medical Tubular Device with Spiropyran

[0365] Samples of small medical tubular devices was produced. Tube shaped host polymer substrates of MED-4720 silicone elastomer, provided from Nusil was provided. The host polymer was loaded with monomers to provide a full IPN and the monomers was cross-linked e.g. as described elsewhere herein.

[0366] The hydrogel content in the medical tubular devices was >30% by dry weight.

[0367] The co-monomer was 2-hydroxyethyl methacrylate (HEMA) and a minor percentage of spiropyran as shown in FIGS. 8a and 8b. The percentage of spiropyran indicated is the percentage of monomers in the feed during monomer loading.

[0368] In FIG. 8a, 3 times 3 samples with varying spiropyran content of the samples of the medical tubular devices are shown after having being immersed in water to full saturation. The samples have a light brownish colour, which mean that the spiropyran is in its spiro form.

[0369] In FIG. 8b, 3 samples with varying spiropyran content (approx. 10, 20 and 30% by weight of hydrogel) are shown after having being immersed in water to full saturation and subject to UV illumination. The samples are dark purple, i.e. it is in its merocyanine form.

[0370] This property may be very advantageous e.g. to trigger drug delivery, and/or attach/detach to cells. The change between SP and MC form changes the hydrophilicity of the polymer, due to the formation of a zwitterionic moiety.

[0371] In addition this property may be used to ensure that a medical tubular device has been correct implanted during surgery. Before closing up, the surgeon may illuminate the medical tubular device and control the fixation and tightness of the medical tubular device.

Example 3—Chitosan Loading

[0372] Flat disc shaped samples (Ø 10 mm, thickness 2.0 mm) of silicone (PDMS) polymer was punched from an extruded PDMS strip delivered from Lebo Production (Lebo Production, Skogaas, Sweden) with the trade name “PE4062”. 6 samples were arranged in a 16 ml reactor and impregnated with guest polymer PHEMA (poly(2-hydroxyethyl methacrylate)) using CO.sub.2 to a pressure of 300 bar at 22° C. for 24 hours. The pressure was slowly released and 3 of the samples (blinds) were collected in airtight bags.

[0373] The 3 remaining samples were loaded with chitosan in the 16 ml reactor

[0374] The reactor was filled with 10 ml of 10 mg/ml chitosan solution (100 g chitosan in 7.5 ml EtOH, 2 ml H.sub.2O and 1 ml acetic acid).

[0375] The reactor was pressurized using CO.sub.2 to a pressure of 300 bar at 22° C. for 24 hours.

[0376] The pressure was slowly released and the 3 samples were collected in airtight bags.

[0377] Experimental setup for testing of bioadhesion: Bioadhesion was measured on a Texture Analyzer Texture (TA:.XT.plus, TA Instruments). Bioadhesion was simulated on absorbent paper wetted with a 2% porcine gastric mucus (Sigma) solution in phosphate buffer pH 6.8. Discs were pressed against the mucus-wetted paper for 180 s before removed. Adhesion was measured as peak force necessary to remove discs and total work to remove disc (area under the curve).

[0378] The results are shown in figured 9a and 9b.

Example 4—Chitosan Detection

[0379] Samples obtained from example 3 are each stained with 0.5 ml 0.1% (w/v) Fluorescent Brightener 28 (FB28 Sigma F3543) dissolved in 0.5M Tris.HCl, pH 9.

[0380] Surplus of stain is removed by washing three times. Each wash consists of 0.5 ml of water.

[0381] Devices not treated with chitosan (Blind) are used as references for the evaluation of fluorescence related specifically to the presence of chitosan in devices that have been treated.

[0382] Fluorescence is monitored by placing devices on a UV transilluminator (302 nm) and documenting the emission with CCD pictures (G:BOX, Syngene). These pictures can be quantitatively accessed for estimation of relative content or with reference to devices containing known amounts.

Example 5—Attaching Chitosan to Silicone

[0383] A number of chitosan foams is produced by freeze-drying chitosan gels with concentration of chitosan of about 0.5%, 1%, and 2%.

[0384] The chitosan foams have thickness between 0.5 and 1 mm. Samples are cut into 1 cm.sup.2 pieces.

[0385] Samples of standard silicone are cut into 1 cm.sup.2 pieces in order to match the sizes of KitoZyme chitosan foam preparations.

[0386] Foams is attached to a number of the standard silicone slabs by using Sylgard 184 (Dow Corning, Diatom) for attaching. Uncured Sylgard 184 is applied onto the surface of cast standard silicone using a brush.

[0387] Chitosan powders of particle size below 80 μm is provided. The powder is attached to the surface of a number of silicone samples by dipping the cast standard silicone samples into uncured Sylgard 184 silicone and then bring the surfaces in contact with the powder.

[0388] It will be seen that powdered chitosan is easily applied onto the surface of cast standard silicone and appear to be surface accessible. Chitosan remain attached after overnight incubation. This allow all edges to be covered.

[0389] It will further bee seen that the chitosan foam with big pores allow for efficient attachment onto the silicone surfaces. The chitosan foam remains attached after overnight incubation in water. The foam appears to become embedded in the Sylgard elastomer and is expected to be less available to cell interaction than the powdered chitosan.

[0390] Further it will be seen that also chitosan with smaller pores allow for efficient attachment onto the surfaces of cast silicone. The chitosan foam remains attached after overnight incubation in water. The foam appears to become completely embedded in the Sylgard elastomer and is expected to have far less chitosan available for cell interaction than the powdered chitosan.

Example 6—Pig Test

[0391] A provoked surgical site infection (SSI) animal (pig) model was established. To compare Interpenetrating polymer network (IPN) vascular graft material and currently used heparin coated ePTFE material (Gore-Tex) for infection resistance, by direct contamination with Staphylococcus Aureus in a porcine model.

[0392] IPN patches (Host polymer: MED-4720 silicone elastomer/Guest polymer: PHEMA-co-PEGMEA—with 23% hydrogel) was loaded.

[0393] Loading was done 2 weeks prior to experiments. The loading was done in two steps. In step 1, the patches were loaded in 10 mg/ml rifampicin in 96% ethanol for one week. In step 2, the patches were loaded in a 10 mg/ml minocycline solution in MilliQ water saturated with rifampicin (approx. 2.5 mg/ml) for one week. On the day of experiment, the patches were washed by incubation in PBS at room temperature for 15 minutes prior to insertion.

[0394] The direct comparison experiment was conducted on six female Danish Landrace pigs weighing about 80 kg. On the right side of the pigs, six Gore-Tex Propaten CBAS Heparin coated vascular graft patch (20.0×10.0×0.6 mm) were implanted and on the left side, six IPNs of same dimensions were implanted. These patches were inoculated with 10.sup.6 Staphylococcus aureus. The implants were removed after 14 days.

[0395] In a first run, the dose of S. aureus was changed from 10.sup.3 to 10.sup.7. It was found that the optimal challenge was 10.sup.6 bacteria. Therefore, a second run was made with 10.sup.6 bacteria. The second run was conducted on two female Danish Landrace pigs weighing about 80 kg.

[0396] The patches were analyzed for concentration of S. aureus and the result is shown in FIG. 13. It can be seen that there is much less infection at the IPN patches than at the Gore patches

[0397] FIG. 10 shows the right side of one of the pigs with the markings showing where the patches are implanted.

[0398] FIG. 11a show an IPN Patch after 14 days, where the patch initially was inoculated with 10.sup.6 S. aureus.

[0399] FIG. 11b show a Gore Patch after 14 days, where the patch initially was inoculated with 10.sup.6 S. aureus.

[0400] It can be seen that the IPN patch suppresses the infection. The P value was determined on the hypothesis that the risk of infection was not dependent on the patch used. Since the P value in very low there is a clear indication that this hypothesis is not correct and that there in fact is a much lower risk of infection using the IPN patch relative to the Gore patch. Rifampicin and minocycline loaded IPN has been tested in one additional round of a porcine subcutaneous infection model and compared with state-of-the-art Gore graft material. The second run was conducted on two female Danish Landrace pigs weighing about 80 kg with a bacteria challenge/load of 10.sup.6 bacteria in each surgical site wound.

[0401] The results (cf. FIG. 12) showed again better performance for the IPN material, with approx. 10.sup.3 times reduction in biofilm bacteria associated with the IPN material compared to Gore's Propaten.

Example 7—Loading with Taxol

[0402] A number of medical tubular device were produced:

[0403] IPN host polymer: Nusil MED-4720 silicone elastomer extruded into thin tubing by Vesta (USA). The tubing of host polymer had the following dimensions: ID 5.0 mm, wall thickness 0.75 mm.

[0404] IPN guest polymer: copolymer of PHEMA, PEGMEA-480 (Poly(ethylene glycol) methyl ether acrylate average Mn 480) and CK1573 (vinylimidazole butyl sulfonate).

[0405] Hydrogel content (dry) was 41%.

[0406] A sample of the medical tubular devices (unloaded medical tubular device) was packed in an airtight bag.

[0407] IPN graft was loaded in taxol stock solution for 5 days. “Paclitaxel “Fresenius Kabi”: 6 mg/ml PTX in 50:50 solution of ethanol and ricinus oil. http://pro.medicin.dk/Medicin/Praeparater/5984

[0408] After loading, the medical tubular devices were packed in airtight bags.

Example 8—Release

[0409] The unloaded medical tubular device of example 7 (Control) and one taxol loaded medical tubular device of example 7 were used.

[0410] The control sample and the taxol loaded sample were each immersed in an aqueous cell growth medium. After each week a small sample of each aqueous cell growth medium are withdrawn and are added into respective wells and about 25,000 endothelial cells (EA.hy926 endothelial cell culture) are added to each well. After two days, the cells are counted.

[0411] The results are shown in FIG. 14. It can be seen that after 21 weeks, the IPN graft still exhibit release of Taxol at levels that completely inhibits endothelial cell growth.

Example 9—Sheep Test

[0412] We identified a special race of sheep bred at the south west coast of Jutland (Denmark), which are relatively calm and easily handled postoperatively.

[0413] Five sheep were selected for the test. An end-to-side bypass operation of the common carotid artery bilaterally in each sheep was performed, using a Gore® Propaten CBAS heparinized graft and a taxol loaded medical tubular (IPN) device of example 7 as graft at respective sides of the sheep. The sheeps were monthly inspected by duplex scanning.

[0414] After 6 month, the grafts were removed.

[0415] FIG. 15a show one of the Gore® Propaten CBAS heparinized graft. FIG. 15b show one of the taxol loaded medical tubular IPN device of an embodiment of the invention.

[0416] It can be seen that the Gore® Propaten heparinized graft appears to be completely closed, whereas the IPN devices appears to be fully open and with no signs of hyperplasia.

Example 10—FMOC Procedure

[0417] Four samples each 1 cm×4 cm×1 mm were used:

TABLE-US-00001 Sample A Silicone PMDS Sample B IPN Host: PMDS; Guest: PHEMA hydrogel Sample C IPN Host: PMDS; Guest: PHEMA-co- PEGMEA hydrogel Sample D IPN Host: PMDS; Guest: PHEMA-co- PEGMEA-co-CK1594 hydrogel

[0418] The CK1594 monomer forming part of the hydrogel guest polymer in sample D is a monomer with an FMOC protected amine as shown in FIG. 16.

[0419] The samples were placed in a 4 compartment wire-mesh basket and immersed into 25 ml beakers containing the reagents:

[0420] Deprotection: 20% piperidine in DMF for 2×2 min.

[0421] Coupling: 0.38 mmol HBTU, 0.37 mmol linker, 0.5 mmol DIPEA in 20 ml DMF.

[0422] Capping: 20% acetic anhydride in MeOH for 2 hours.

[0423] FITC (Fluorescein isothiocyanate) tagging: 0.1 mg/ml FITC in DMF for 2 hours.

[0424] Washing: Subjects were rinsed with MeOH and washed in DMF for at least 3×10 min between and after reactions.

[0425] Storage: Subjects were stored in DMF between reactions.

[0426] FITC has excitation and emission spectrum peak wavelengths of approximately 495 nm/519 nm, giving it a green colour. The samples were examined and the following was observed:

TABLE-US-00002 Sample A No sign of FITC Sample B No sign of FITC Sample C Very weak sign Sample D Clear strong sign of FITC

[0427] The weak signal in sample C may be explained by absorption of FITC in the hydrogel. However, the signal is very weak compared to the signal of sample D, indicating that the signal observed in sample D is from attaching/reacting FITC to the IPN.

Example 11—Heparin Grafting

[0428] A medical tubular IPN graft (OD 5 mm, ID 3 mm) comprising a host polymer of PMDS and a guest polymer forming at least a luminal surface guest polymer domain of PHEMA-co-PEGMEA-co-CK1594 hydrogel is produced (same method as sample D from example 10).

[0429] The IPN graft is arranged to be contacted with fluids at its luminal surface as shown in the setup of FIG. 4, but without the second container.

[0430] The luminal surface is reacted with deprotection fluid, coupling fluid and capping fluid following the scheme of example 10. Thereafter the luminal surface is reacted with heparin.

[0431] Heparin entities containing free terminal aldehydes of US2011064781 (Examples 1 through 6) is dissolved in DI water, pH 3.9 together with NaCl (approximately 0.5 g heparin and 2.95 g NaOH per 100 ml).

[0432] The luminal surface is contacted with the heparin solution at a temperature of 50 to 60° C. for 1-2 hours.

[0433] Thereafter the IPN graft is washed in water.

[0434] Further scope of applicability of the present invention will become apparent from the description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Example 12—Zwitterionic IPNs

[0435] A number of zwitterionic IPN samples was prepared using zwitterionic monomers as listed in FIG. 6.

[0436] Silicone samples (tubings with outer diameter (OD): 5.10 mm, inner diameter (ID): 4.10 mm, thickness:0.50 mm; approx. 35 g) were organized in a stainless steel grid and placed in a one-litre reactor (1 L, BC-2, HiP, Pennsylvania, USA) on top of a 4 cm magnet bar (for stirring). Approximately 100 mL HEMA, 100 mL PEGMEA, 5 g zwitterionic monomer, 6 mL EGDMA, 50 mL 0.2M DEPDC in hexane, 70 mL EtOH and 70 mL THF (tetrahydrofuran) were mixed for 20 min in a separate beaker. The solution was then added to the reactor and the reactor was closed with the corresponding bolts with a torque of 125 ft-lb. The reactor was placed on top of a magnet stirrer (Ret Basic, IKA, Germany). The reactor was wrapped in a custom made heating jacket. Inlet and outlet was placed on top of the reactor, however inlet tubing was let to the bottom of the reactor for proper mixing and outlet tubing was let to a waste container. All tubing was 1/16″ with an internal diameter of 0.03″ (15-9A1-030, HiP, Pennsylvania, USA). A pressure transmitter was connected to the inlet. Pressure and temperature were monitored and logged through a custom made LabView program. A Thar P-50 electrical driven high-pressure pump from Thar Designs Inc. USA is applied for assuring the operation pressure. The pump was equipped with a heat exchanger and was supplied with cooling water at 5° C. CO.sub.2 was added to the reactor to a pressure of 300 bar at 40° C. for approx. 16 h. During this time monomers diffused into the swollen silicone, polymerize and cross-link. Then the pressure was lowered through the outlet tubing to the waste container.

[0437] Depressurizing the reactor takes between 30-60 minutes. Subsequent the reactor was first cleaned with ethanol and subsequently with demineralized water. The produced IPN samples were collected and excess polymer was removed by rinsing in tap-water. Excess monomer and uncrosslinked polymer were extracted by placing the IPN samples in 96% EtOH for 1 week. Then the IPN samples were dried until constant weight before the hydrogel content was determined by weighing.

[0438] The produced samples are listed in table 1

TABLE-US-00003 TABLE 1 Zwitterionic Hydrogel monomer No. content Name (FIG. 6) Zwitterionic monomer W/W % 1582- CK1582 3-[dimethyl(2-{2-[(2-methylprop-2- 29.77 G9 enoyl)oxy]ethoxy}ethyl)azaniumyl]propane-1- sulfonate 1578- CK1578 1-methyl-4-(2-methyl prop-2-enoyl)-1-(4- 30.10 G9 sulfonatobutyl)piperazin-1-ium 1572- CK1572 1-Ethenyl-3-(3-sulfonatopropyl)-1H-imidazol-3- 31.28 G9 ium 1583- CK1583 4-[dimethyl({2-[(2-methylprop-2- 27.93 G9 enoyl)oxy]ethyl})azaniumyl]butane-1-sulfonate 1591- CK1591 4-(2-methylprop-2- 51.07 G9 enoyloxymethoxymethylammonio)butane-1- sulfonate 1584- CK1584 4-{dimethyl[3-(2-methylprop-2- 35.39 G9 enamido)propyl]azaniumyl}butane-1-sulfonate 1586- CK1586 1-methyl-4-(2-methylprop-2-enoyl)-1-(4- 17.03 G9 sulfonatobutyl)piperazin-1-ium 1573- CK1573 1-Ethenyl-3-(4-sulfonatobutyl)-1H-imidazol-3- 46.08 G9 ium 1581- CK1581 1-carboxy-N,N-dimethyl-N-(2′- 35.50 G9 methacryloyloxyethyl)methanaminium 1589- CK1589 2-[dimethyl(2-{2-[(2-methylprop-2- 35.50 G9 enoyl)oxy]ethoxyl-ethyl)azaniumyl]acetate 1588- CK1588 2-{dimethyl[3-(2-mehtylprop-2- 42.51 G9 enamido)propryl]-azamniumyl}acetate 1585- CK1585 1-(carboxylatomethyl)-1-methyl-4-(2- 42.93 G9 methylprop-2-enoyl)piperazin-1-ium 1587- CK1587 3-(carboxylatomethyl)-1-ethenyl-1H-imidazol- 43.68 G9 3-ium 1573- CK1573 1-Ethenyl-3-(4-sulfonatobutyl)-1H-imidazol-3- G8 ium 1573- CK1573 1-Ethenyl-3-(4-sulfonatobutyl)-1H-imidazol-3- G10 ium

[0439] The G7/G8/G9 part of the name indicates the silicone used.

[0440] G7: Nusil Med 4020, Durometer: 25 Type A (extruded tubing (Vesta, US) L=2m, wall=0.5 mm, φ(inner)=4.1 mm.

[0441] G9: Nusil Med 4720, Durometer: 25 Type A (extruded tubing (Vesta, US) L=2m, wall=0.75 mm, φ(inner)=5 mm).

[0442] G10: Nusil Med 4027, Durometer: 30 Type A (extruded tubing (Vesta, US) L=0.5m, wall=0.75 mm, φ(inner)=5 mm).

Example 13—Thrombin-Antithrombin Complex (TAT) Level

[0443] A number of the IPN samples from example 12 was tested for blood compatibility. The zwitterion-based IPNs were evaluated using enzyme-linked immunosorbent assay (ELISA) that specifically measures the thrombin-antithrombin (TAT) and complement split-product C3c as sensitive markers for coagulation and complement activation, respectively. Both markers are included in the ISO standard 10993-4 for evaluation of biomaterials.

[0444] Plasma samples incubated on zwitterionic IPNs and samples of silicone (reference samples) were analyzed for Thrombin-Antithrombin (TAT) levels using ELISA. Maxisorp plates were coated with 2.0 μg/ml anti-TAT monoclonal antibody (HYB 14-22) O/N at 4° C. The next day, the plates were washed three times in PBS with 0.05% Tween-20 and blocked for 15 min. Samples of human plasma were diluted to 1:320, and a serum pool diluted from 1:100 to 1:1024 was used as standardized samples using dilution in PBS+0.1% BSA+aggregated IgG+10 mM EDTA. Samples were incubated for 1 hour at room temperature and washed as previously. The biotinylated secondary antibody 230-01 was diluted to 1:500 and incubated for 1 hour. Each plate was washed and streptavidin-conjugated HRP was added at 1:4000 and incubated for 30 min followed by 3× wash. Color was allowed to develop for 15 min using OPD/H.sub.2O.sub.2 solution and stopped with 100 μl of 1M H.sub.2SO.sub.4. The plates were measured at 490 nm using 650 nm as reference, and then quantified for TAT concentrations using the SoftMax Pro software.

[0445] The results are shown in FIG. 17.

Example 14—Zwitterionic IPNs with Different Amount of Zwitterionic Monomer

[0446] A number of zwitterionic IPN samples was prepared using three different amount of the zwitterionic monomer CK1573. The zwitterionic IPN samples were produced as described in example 12, but using respectively 2 g, 5 g, and 10 g zwitterionic monomer.

[0447] Six samples of each type (2 g, 5, and 10 g zwitterionic monomer) were tested as described in example 13 using defibrinated plasma and citrated plasma respectively. Each group was compared to the silicone control using Dunnett's test for significance. P-values <0.05 were defined as significant, and shown as *P<0.05, **P<0.01, ***P<0.001.

[0448] The results are shown in FIG. 18A (defibrinated plasma) and FIG. 18B (citrated plasma)

Example 15—Zwitterionic Polymer Coating Suppress Protein Adsorption

[0449] Two test containers A and B, each with a volume of 5 L was provided. The containers have an inner surface of aluminum.

[0450] The inner surface of container A is coated with a zwitterionic containing hydrogel coating. The zwitterionic containing hydrogel coating is provided from HEMA, PEGMA and zwitterionic monomer 1573 in the relative molar amounts 35:10:1.

[0451] The container A was first subjected to a silane coupling agent surface treatment. The inner surface of the container was cleaned and a solution of 3-methacryloxypropyl trimethoxy silane (2 wt % v/v in an acetic acid/water/ethanol mixture, 0.01:1:4) was applied onto the inner surface. After 2h the inner surface was rinsed with ethanol and dried.

[0452] The hydrogel coating was prepared by monomer polymerization directly onto the silanized solid substrates. The surface was subjected to an aqueous precursor solution of the monomers and subjected to UV photopolymerization (365 nm wavelength, 30 mW cm.sup.−2) for 30 min. Thereafter the container was filled with pure water 3 days until they reached swelling equilibrium.

[0453] The precursor solution comprises HEMA, PEGMA and zwitterionic monomer 1573 in the relative molar amounts 35:10:1 and 0.5 mol % of cross-linker, and 0.5 mol % of an initiator.

[0454] 3 L of fresh milked cow milk is added into each container and hold there for 3 hours a 5° C. Thereafter the containers were emptied and cleaned by spraying tap water (20° C.) onto the surfaces for 1 minute. Thereafter the surfaces were examined for adsorbed protein.

[0455] The amount of protein remaining on the inner surface of container A is highly reduced compared to the amount of protein remaining on the inner surface of container B.

Example 16—Gradient Loading of Taxol in Inner Lumen and Luminal Surface of a Medical Tubular Device (a Graft)

[0456] Where there may be risk of cell growth inside the lumen of the medical tubular device, it is desired that the anti-proliferative drug is located at least as a part of the luminal surface.

[0457] The graft was sterilized by sonication of two turns in 70 vol. % ETOH for 5 min. The graft was then dried over the weekend in sterile Petri dishes in sterile benches.

[0458] The graft was mounted vertically on a stand with clamp at the bottom and with pipette tip at the top mounted on with strips.

[0459] Pure taxol solution (6 mg/ml taxol in a a 50:50 mixture of ethanol and castoroil, Fresenius-Kabi) was filled into the lumen of the graft and air bubbles were massaged out during filling.

[0460] It was charged for 2½ hours in a sterile bench. The graft was emptied and rinsed vigorously inside using 100 ml of 70 vol. % ETOH applied with rod pipette. The exterior and interior were rinsed from the top with approximately 300 ml of 70 vol. % ETOH.

[0461] The graft was briefly dried on a tripod and then cut into 10-14 cm graft pieces, which were placed in sterile autoclave bags, which were then sealed. The graft pieces are now ready for use in surgery.

Example 17—Synthesis of 1-ethenyl-3-(4-sulfonatobutyl)-1H-imidazol-3-ium (CK1573)

[0462] A 1 L, 3-necked round-bottomed flask was fitted with mechanical stirrer, contact thermometer and N2-bubbler. The flask was charged with 1,4-butane sultone (0.48 mol, 63.4 g), 1-vinylimidazole (0.40 mol, 37.6 g) and MeCN (250 mL). The reaction was stirred at 60° C. for 72 hours in the dark. The reaction was diluted with MeCN (125 mL) and cooled to room temperature with stirring to keep the precipitate suspended. The reaction mixture was filtered and the reaction flask was rinsed with MeCN to transfer the remaining precipitate to the filter. The solids were washed with MeCN (250 mL) and MTBE (2×100 mL) and dried under reduced pressure for 24 hours to give the title product 87.5 g (95%) as a white solid. 1H NMR (300 MHz, D2O) δ 7.80 (d, J=2.2 Hz, 1H), 7.63 (d, J=2.1 Hz, 1H), 7.16 (dd, J=15.6, 8.7 Hz, 1H), 5.82 (dd, J=15.6, 2.8 Hz, 1H), 5.45 (dd, J=8.7, 2.8 Hz, 1H), 4.32 (t, J=7.1 Hz, 2H), 3.02-2.94 (m, 2H), 2.14-2.02 (m, 2H), 1.85-1.72 (m, 2H). 13C NMR (75 MHz, d2o) δ 134.2 (t, 1JC-D=34 Hz), 128.1, 122.7, 119.5, 109.3, 49.9, 49.2, 27.9, 20.8.

[0463] One imidazole proton is missing due to deuterium exchange which also causes the 13C triplet at 134.2 ppm.

Example 18: Synthesis of 1-ethenyl-3-(3-sulfonatopropyl)-1H-imidazol-3-ium (CK1572)

[0464] A 1 L, 3-necked round-bottomed flask was fitted with mechanical stirrer, contact thermometer and N2-bubbler. The flask was charged with 1,3-propane sultone (0.48 mol, 58.6 g), 1-vinylimidazole (0.40 mol, 37.6 g) and MeCN (200 mL). The reaction was stirred at room temperature for 72 hours in the dark. The reaction was diluted with MeCN (125 mL) to keep the precipitate suspended. The reaction mixture was filtered and the reaction flask was rinsed with MeCN to transfer the remaining precipitate to the filter. The solids were washed with MeCN (250 mL) and MTBE (2×100 mL) and dried under reduced pressure for 24 hours to give the title product 86.3 g (>99%) as a white solid. 1H NMR (300 MHz, D2O) δ 7.82 (d, J=2.2 Hz, 1H), 7.66 (d, J=2.2 Hz, 1H), 7.17 (dd, J=15.6, 8.7 Hz, 1H), 5.83 (dd, J=15.6, 2.8 Hz, 1H), 5.46 (dd, J=8.7, 2.8 Hz, 1H), 4.44 (t, J=7.2 Hz, 2H), 3.02-2.90 (m, 2H), 2.45-2.28 (m, 2H). 13C NMR (75 MHz, D2O) δ 134.4 (t, 1JC-D=34 Hz), 128.1, 122.7, 119.6, 109.4, 48.0, 47.1, 24.9.