Medical device and method for manufacturing the same

Abstract

The present invention provides a device comprising a device body (12) preferably comprising a material susceptible to corrosion or biodegradation, and a shellac coating (14) at least partially covering the device body (12), The shellac coating 14 has a thickness of 0.1 μm to 20 μm on the medical device 10. The present invention further relates to a method for manufacturing the medical device.

Description

Technical Field

[0001] The present invention relates to a medical device including a device body and a shell coating.

Background Art

[0002] Magnesium is a promising material in the field of medicine due to its material properties (e.g., low weight in vivo and corrosive or biodegradable decomposition into harmless decomposition products). On the other hand, rapid and uncontrollable corrosion or biodegradation in vivo, which results in the release of a large amount of hydrogen, is still a serious risk.

[0003] To delay the corrosion or biodegradation of magnesium, magnesium may be directly modified, for example, by converting the magnesium surface into a layer of magnesium fluoride (MgF2) or other inert magnesium compounds that are difficult to corrode or biodegrade. However, such a layer of magnesium compound is often brittle and cracks or peels off during the manufacturing process that requires deformation processing of the medical device. Furthermore, such magnesium compounds often exhibit only limited biocompatibility, which is particularly disadvantageous when distributed in the patient's body (blood stream) during decomposition. Moreover, such a layer of magnesium compound does not exhibit the mechanical properties of the substrate of the medical device, such as magnesium or magnesium alloy, and thus must be considered during the manufacture of the medical device.

[0004] According to a further approach to retard the corrosion or biodegradation of magnesium, magnesium can be coated with a biodegradable polymer such as polycaprolactone or polylactide. However, mainly, such degradable polymer coatings are troubled by two water intakes. First, the degradation of such polymers is typically based on hydrolysis, which mostly occurs very slowly. Faster degradable polymers are often swellable and thus take up a fairly large volume during degradation. Both scenarios result in a fairly complex manufacture of medical devices that require good adaptation and adjustment of the device dimensions.

[0005] Second, in the case of large medical devices, degradable polymer coatings can only retard the onset of corrosion or biodegradation. When water penetrates the polymer, corrosion or biodegradation is typically no longer controllable. Thus, there is a fairly high risk, especially the risk of explosive release of hydrogen. Furthermore, the location of hydrogen release can occur sporadically and unexpectedly. Then, a large amount of magnesium has its degradation accelerated due to the large surface, and as a result, the mechanical stability is rapidly lost.

[0006] A stent comprising a magnesium alloy that can be degraded under physiological conditions and an outer polymer coating is known from WO 2013 / 024125 pamphlet.

[0007] EP3120877A1 refers to an intraluminal device comprising a first structure and a second structure, the first structure comprising at least one metal selected from the group consisting of magnesium, zinc, iron and their alloys, and the second structure comprising at least one polymer selected from the group consisting of polylactide, polycaprolactone, poly(trimethylene carbonate), their copolymers, and their mixtures. Summary of the Invention Problems to be Solved by the Invention

[0008] Accordingly, in view of the above, a basic object of the present invention is to make available a medical device and a process for manufacturing the medical device, the medical device at least partially avoiding the drawbacks as described above in the context of general medical devices, and in particular facilitating a more controllable degradation, especially based on corrosion or biodegradation in vivo.

Means for Solving the Problems

[0009] This object is achieved by the medical device according to independent claim 1 and the method for manufacturing the medical device according to independent claim 15. Preferred embodiments are defined in the dependent claims and in the present specification. The subject matter and terms of all claims are hereby incorporated into the present specification by explicit reference, respectively.

[0010] According to a first aspect, the present invention relates to a medical device. The medical device comprises a device body. Preferably, the device body comprises or consists of a material that is susceptible to corrosion or biodegradation, especially corrosion or biodegradation in vivo. Further, the medical device comprises a shellac coating. The shellac coating can be in the form of a single layer or a multi-layer, especially a two-layer, three-layer or four-layer shellac coating.

[0011] The device body is at least partially, especially only partially or completely, covered or coated with a shellac coating. Preferably, the device body is immediately at least partially, especially only partially or completely, covered or coated with a shellac coating.

[0012] Preferably, the medical device is characterized in that the shellac coating has a thickness of from 0.1 μm to 20 μm.

[0013] The term "shellac" as used in accordance with the present invention typically refers to the resin secreted by the female lac bug on the trees of the forests of India and Thailand. It is processed, sold as dry flakes, and can also be dissolved in alcohol to produce liquid shellac. For its production, shellac is scraped from the bark of the tree where the female lac bug, Kerria lacca (Hemiptera, family Kerriidae, also known as Laccifer lacca), secretes it and forms tunnel-like tubes when crossing the branches of the tree. The raw shellac containing the bark shavings and lac bugs removed during scraping is placed in a canvas tube and heated over a fire. This causes the shellac to liquefy and ooze out of the canvas, leaving behind the bark and bugs. Next, the thick, sticky shellac is dried to form a flat sheet, crushed into flakes, or dried into "buttons" (packs / cakes), then bagged and sold. The end user then grinds the flakes into a fine powder before use and mixes it with ethyl alcohol to dissolve it and produce liquid shellac. Liquid shellac has a limited storage period (about 1 year). Thus, shellac is typically sold in dry form for dissolution before use. Shellac, of course, contains a small amount of wax (3 to 5% by volume) derived from the lac bug. In some preparations, this wax is removed. The resulting product is called "dewaxed shellac".

[0014] Useful shellacs applicable within the scope of the present invention are commercially available, for example, under the designation shellac (ph.Eur.) CAS 9000-59-3 and under the trade names Schellack SSB 55 PHARMA FL, Schellack SSB 56 PHARMA FL, and Schellack SSB 57 PHARMA FL by SSB (Stroever Schellack Bremen).

[0015] The term "shellac coating" as used in accordance with the present invention refers to a coating that contains or consists of shellac and, in particular, contains any possible components in addition to shellac, such as wax.

[0016] The present invention is characterized, in particular, by the following advantages: Surprisingly, it has been found that shellac can act as a barrier or protective coating that delays the corrosion or biodegradation of the device body, particularly in vivo (i.e., upon contact with tissue fluid such as blood), of materials that are particularly susceptible to the effects of corrosion or biodegradation, such as magnesium or magnesium alloys.

[0017] Advantageously, the shellac coating exhibits a certain degree of stability against water and, in particular, exhibits only limited water permeability. Thus, the desired properties of the device body, particularly those of materials susceptible to corrosion or biodegradation, can be maintained in the body for as long as possible.

[0018] The accelerated degradation of shellac occurs only from a pH value of 8 or higher. Thus, tissue fluids such as blood (pH value 7.4) cannot promote the degradation of shellac. On the other hand, the degradation of materials susceptible to corrosion or biodegradation, such as magnesium and magnesium alloys, causes an increase in the pH value. Thus, the degradation of the shellac coating can be incorporated into the degradation process of materials susceptible to corrosion or biodegradation. Undesirably early degradation of the shellac coating, and thus undesirably early degradation of materials susceptible to corrosion or biodegradation, can be advantageously avoided. Thus, also in this regard, the desired properties of the device body, particularly those of materials susceptible to corrosion or biodegradation, can be maintained for as long as possible.

[0019] Furthermore, the degradation rate of the shellac coating, and thus the degradation rate of the device body, particularly that of materials susceptible to corrosion or biodegradation, can be advantageously controlled by the thickness of the shellac coating. Thus, when the device body is susceptible to the effects of corrosion or biodegradation, any adverse effects associated therewith, such as gas evolution or dissipation during corrosion or biodegradation, as well as cell growth impairment and / or delay in healing, can be advantageously prevented.

[0020] Compared to conventional polymer coatings, the use of shellac advantageously achieves a delayed, particularly controllable, degradation, particularly corrosion or biodegradation, of the device body, particularly of materials susceptible to corrosion or biodegradation, requiring a lower coating thickness.

[0021] Furthermore, shellac is according to the European Pharmacopoeia and thus represents a biocompatible, particularly non-thrombogenic, material. In particular, shellac is a material that does not adversely affect cell growth.

[0022] Furthermore, the thickness of the shellac coating may advantageously be adjusted locally on the device body. Thus, the targeted degradation, particularly corrosion or biodegradation, of the device body, particularly of materials susceptible to corrosion or biodegradation, is achievable. In particular, the location and amount of gas evolution or dissipation, particularly of hydrogen, can be advantageously controlled and / or reduced. For example, it is possible to have different thicknesses of the shellac coating and thus different rates of degradation, particularly corrosion or biodegradation, of the device body, particularly of materials susceptible to corrosion or biodegradation, promoting parts. Thus, it is possible to prevent gas evolution or dissipation, particularly of hydrogen, on the surface area of the device body. Thus, for example, local impairment of cell growth due to gas accumulation, particularly of hydrogen, and thus any adverse effects on the healing process can be avoided. This is particularly advantageous with respect to implants useful for the fixation of fractures.

[0023] In contrast to conventional polymers such as poly(D,L) lactide, shellac is characterized by a low swelling tendency. This property of shellac is also useful for avoiding the undesirable early degradation, particularly corrosion or biodegradation, of the shellac coating and thus of the device body, especially of materials that are particularly susceptible to corrosion or biodegradation.

[0024] Furthermore, the shellac coating can be applied to the device body by various different processing techniques such as dipping, wetting, spraying, dripping, atomizing, etc. This facilitates better regulation and thus (better) control of the shellac coating.

[0025] In contrast to conventional polymers, shellac exhibits a better ability to adhere to materials that are susceptible to the effects of corrosion or biodegradation, such as magnesium or magnesium alloys. This facilitates the more convenient manufacture of medical devices having a shellac coating.

[0026] Furthermore, in contrast to conventional polymers such as poly(L) lactide, shellac is also more biocompatible and thus dissolves in solvents such as ethanol that are less harmful.

[0027] In principle, the shellac coating can have a coating thickness of from 0.1 μm to 2 mm. However, as already mentioned, preferably the shellac coating has a thickness of from 0.1 μm to 20 μm.

[0028] In one embodiment of the invention, the shellac coating has a thickness of from 0.5 μm to 15 μm, particularly from 0.5 μm to 10 μm, preferably from 1 μm to 10 μm, more preferably from 1 μm to 5 μm. The thickness of the shellac coating disclosed in this paragraph is particularly advantageous in terms of realizing the advantages of the invention.

[0029] Generally, it may be preferred within the scope of the invention for the shellac coating to be uniform, i.e., to have a constant thickness (coating thickness).

[0030] However, it may be particularly preferred if the shellac coating has a varying thickness, i.e., includes portions having different coating thicknesses. Thus, in a further embodiment of the present invention, the shellac coating has a varying thickness. In other words, it is preferred that the shellac coating includes different portions with respect to the thickness of the shellac coating. Thus, the decomposition of the shellac coating, and thus the decomposition of the device body, particularly of materials susceptible to corrosion or biodegradation, particularly corrosion or biodegradation, particularly gas evolution, particularly hydrogen evolution, can be advantageously controlled in a targeted manner during the decomposition, particularly during corrosion or biodegradation.

[0031] In principle, the thickness of the shellac coating can be varied in the range from 0.1 μm to 2 mm. Preferably, the thickness of the shellac coating varies from 0.1 μm to 20 μm.

[0032] In a further embodiment of the present invention, the thickness of the shellac coating varies from 0.5 μm to 15 μm, particularly from 0.5 μm to 10 μm, preferably from 1 μm to 10 μm, more preferably from 1 μm to 5 μm. Apply the advantages described in the above paragraph with the necessary modifications.

[0033] In a further embodiment of the present invention, the device body is only partially covered or coated with the shellac coating. In other words, according to a further embodiment of the present invention, the device body comprises some surface areas without a shellac coating, i.e., one (only) surface area or a plurality of surface areas, i.e., two or more surface areas. Thus, during the decomposition of the device body, particularly of materials susceptible to corrosion or biodegradation, particularly corrosion or biodegradation, and thus the evolution of gas, particularly hydrogen, can be controlled or directed towards a target.

[0034] Preferably, the device body of the medical device includes an end without a shellac coating. Thus, during the decomposition of the device body, especially of materials that are particularly susceptible to corrosion or biodegradation, the targeted reduction of gases, especially hydrogen, can be advantageously promoted. Thus, any cell growth disorders and / or delays in healing of the tissue to be treated can be prevented. More preferably, the end of the device body is adapted to be arranged towards soft tissue such as muscle tissue or adipose tissue. Thus, for example, cell growth disorders and / or delays in healing of hard tissue such as bone tissue can be avoided.

[0035] In a further embodiment, the shellac coating has a ratio of 10 -10 wt% to 99 wt%, in particular 0.001 wt% to 20 wt%, preferably 0.01 wt% to 10 wt%, based on the total weight of the medical device.

[0036] In a further embodiment of the invention, the shellac is in the form of a wax containing shellac. Thus, in this embodiment of the invention, the shellac coating comprises shellac wax. Furthermore, the wax may have a proportion of 0 wt% to 10 wt%, in particular 0.1 wt% to 10 wt%, in particular 0.1 wt% to 8 wt%, preferably 1 wt% to 6 wt%, based on the total weight of the shellac coating. Advantageously, the wax makes the shellac coating more flexible and also softer.

[0037] In a further embodiment of the invention, the shellac does not contain wax, i.e. is in the form of wax-free shellac. Wax-free shellac is hard and tends to be brittle.

[0038] In a further embodiment of the invention, the device body of the medical device comprises voids, in particular pores. In particular, the device body may be in the form of an open-pored device body. Preferably, the voids, in particular the pores, are at least partially, in particular only partially or completely, filled with a shellac coating. Thus, differences in the degradation rate, in particular the corrosion or biodegradation rate, and / or differences in the degradation, in particular the local occurrence of corrosion or biodegradation, of materials of the device body that are particularly susceptible to corrosion or biodegradation can be advantageously introduced.

[0039] In a further embodiment of the invention, the mechanically separated parts and / or the electrically insulated parts of the device body are at least partially, in particular only partially or completely, covered or coated with a shellac coating.

[0040] The term "electrically separated part of the device body" used in accordance with the invention may be understood as a part of a material that is susceptible to the effects of corrosion or biodegradation, in particular a magnesium or magnesium alloy part, which is not in electrical contact, in particular not in electrical contact by means of at least a shellac coating, and is separated. These parts are preferably adhered by shellac. For example, the electrically insulated part of the device body can be in the form of a volumetric bone implant or a multi-layer plate. By using shellac as a coating, parts that are not in electrical contact have their own corrosion or biodegradation rate, or corrosion or biodegradation is prevented by the protection of the material and the outer layer of the shellac. Thereby, the generation of hydrogen is reduced and can dissolve for optimal healing according to the healing mechanism of the body part.

[0041] In a further embodiment of the present invention, the device body of the medical device comprises at least one filament or is in the form of at least one filament. The at least one filament may be selected from the group consisting of at least one wire, at least one monofilament, at least one pseudo-monofilament, and at least one multifilament. The at least one filament is preferably at least partially, particularly only partially or completely, covered or coated with a shell coating.

[0042] Furthermore, the device body of the medical device may comprise only one filament or be in the form of only one filament. The filament can be selected from the group consisting of a wire, a monofilament, a pseudo-monofilament, and a multifilament. The filament is preferably at least partially, particularly only partially or completely, covered or coated with a shell coating.

[0043] Alternatively, the device body of the medical device may comprise a plurality of filaments, particularly wires, monofilaments, pseudo-monofilaments, and multifilaments, or be in the form of a plurality of filaments, particularly wires, monofilaments, pseudo-monofilaments, and multifilaments. Preferably, each filament or at least a part of the filaments is at least partially, particularly only partially or completely, covered or coated with a shell coating. The filaments may be arranged in one direction or randomly. Furthermore, the filaments may have different lengths. In particular, it may be within the scope of the present invention that some of the filaments, particularly the inner filaments, do not reach the outside of the device body. Additionally, the filaments may cross each other or be wound around each other. In particular, the filaments may be arranged in the form of a woven fabric or a braid.

[0044] More specifically, the main body of the medical device may include a fabric structure or may be in the form of a fabric structure. The fabric structure may be, for example, a woven fabric, a mesh, a knitted fabric, a warp knitted fabric, or a non-woven fabric (interlaced yarns) such as a knitted fabric.

[0045] In a further embodiment of the present invention, the material susceptible to corrosion or biodegradation is magnesium, i.e., the element or non-oxidized magnesium.

[0046] In a further embodiment of the present invention, the material susceptible to corrosion or biodegradation is a magnesium alloy.

[0047] The term "magnesium alloy" as used in accordance with the present invention refers to a combination of magnesium with another element, particularly another metal (i.e., a metallic element). The magnesium alloy can be in the form of a solid solution, a mixture of metal phases, or an intermetallic compound.

[0048] Preferably, the magnesium alloy comprises magnesium and at least one further metal selected from the group consisting of aluminum, bismuth, copper, cadmium, rare earths such as gadolinium and / or yttrium, iron, thorium, strontium, zirconium, lithium, manganese, nickel, lead, silver, chromium, silicon, tin, calcium, antimony, zinc, and combinations thereof.

[0049] More preferably, the magnesium alloy comprises magnesium and at least one further metal selected from the group consisting of calcium, zirconium, zinc, yttrium, dysprosium, neodymium, europium, and combinations thereof.

[0050] In particular, the magnesium alloy may have a proportion of dysprosium of 5.0 wt% to 25.5 wt% based on the total weight of the magnesium alloy.

[0051] Alternatively, or in combination, the magnesium alloy may have a ratio of neodymium and / or europium of from 0.01 wt% to 5.0 wt% based on the total weight of the magnesium alloy.

[0052] Alternatively, or in combination, the magnesium alloy may have a ratio of zinc of from 0.1 wt% to 3.0 wt% based on the total weight of the magnesium alloy.

[0053] Alternatively, or in combination, the magnesium alloy may have a ratio of zirconium of from 0.1 wt% to 2.0 wt% based on the total weight of the magnesium alloy.

[0054] Furthermore, the magnesium alloy may be selected from the group consisting of: a) A magnesium alloy containing magnesium, yttrium, neodymium, zinc and zirconium, b) A magnesium alloy containing magnesium, yttrium, europium, zinc and zirconium, c) A magnesium alloy containing magnesium, dysprosium, neodymium, zinc and zirconium, d) A magnesium alloy containing magnesium, dysprosium, europium, zinc and zirconium, e) A magnesium alloy containing magnesium, calcium, neodymium, zinc and zirconium, f) A magnesium alloy containing magnesium, calcium, europium, zinc and zirconium g) Combinations of the aforementioned magnesium alloys.

[0055] Also, the magnesium alloy may be a magnesium alloy commercially available under the registered trademark "Resoloy".

[0056] Alternatively, the magnesium alloy may be a magnesium alloy commercially available under the abbreviation "AZ31B". This magnesium alloy contains magnesium, 2.5 wt% to 3.5 wt% aluminum, 0.2 wt% or less manganese, 0.6 wt% to 1.4 wt% zinc, 0.005 wt% or less iron, 0.05 wt% or less copper, 0.10 wt% or less silicon, 0.04 wt% or less calcium, and 0.005 wt% or less nickel, respectively based on the total weight of the magnesium alloy.

[0057] Alternatively, the magnesium alloy may be a magnesium alloy commercially available under the abbreviation "WE43". This magnesium alloy contains magnesium, 3.7 to 4.3 wt% yttrium, 2.4 to 4.4 wt% rare earths, and 0.4 wt% zirconium, respectively based on the total weight of the magnesium alloy.

[0058] Alternatively, the magnesium alloy may be a magnesium alloy commercially available under the abbreviation "AZ31". This magnesium alloy contains magnesium, 3.3 to 4.0 wt% aluminum, 0.25 to 0.50 wt% manganese, 0.05 to 0.20 wt% zinc, 0.003 wt% or less iron, 0.02 wt% or less copper, 0.10 wt% or less silicon, and 0.002 wt% or less nickel, respectively based on the total weight of the magnesium alloy.

[0059] Furthermore, the magnesium alloy may be a magnesium alloy commercially available under the abbreviation "AZ61". This magnesium alloy contains magnesium, 5.92 wt% aluminum, 0.49 wt% zinc, 0.15 wt% manganese, 0.037 wt% silicon, 0.003 wt% copper, and 0.007 wt% iron, respectively based on the total weight of the magnesium alloy.

[0060] Furthermore, the magnesium alloy may be a magnesium alloy commercially available under the abbreviation "AZ91". This magnesium alloy contains magnesium, 9 wt% aluminum, 1.0 wt% zinc, and 0.3 wt% manganese, each based on the total weight of the magnesium alloy.

[0061] Alternatively, or in combination, the device body of the medical device may include or consist of a polymer, particularly a non-degradable polymer, a degradable polymer, or a combination thereof, particularly a blend.

[0062] Non-degradable polymers may particularly be selected from the group consisting of polypropylene, polyethylene, low-density polyethylene, high-density polyethylene, high-molecular-weight polyethylene, ultra-high-molecular-weight polyethylene, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polytetrafluoroethylene, and combinations thereof, particularly blends.

[0063] Degradable polymers may particularly be selected from the group consisting of polylactide, poly(L)-lactide, poly(D,L)-lactide, poly(D)-lactide, polyglycolide, polycaprolactone, poly(trimethylene carbonate), polydioxanone, poly-3-hydroxybutyrate, poly-4-hydroxybutyrate, and combinations thereof, particularly blends.

[0064] Alternatively, or in combination, the device body of the medical device may include or consist of a calcium phosphate material such as hydroxyapatite, α-calcium phosphate, or β-tricalcium phosphate. This is particularly useful when the device body is in the form of a bone replacement material.

[0065] In a further embodiment of the present invention, the medical device is selected from the group consisting of a surgical implant, a stent, a stent graft, an artificial blood vessel, a vascular access, a wound dressing, a suture, a surgical mesh, a surgical wire, a surgical plate, a surgical screw, a surgical nail, a surgical anchor, a surgical clip, a wound closure device, a volume providing an implant for hard tissue, preferably bone tissue, a connector, a medical tube, a bag, a medical needle, and a probe.

[0066] More preferably, the medical device is selected from the group consisting of a surgical implant, a stent, a surgical wire, a surgical plate, a surgical screw, a surgical nail, a surgical anchor, a surgical clip, a wound closure device, and a volume providing an implant for hard tissue, preferably bone tissue.

[0067] The stent may be in the form of a coronary stent or a peripheral stent.

[0068] The surgical wire may be in the form of a wire for bone fixation. For example, the surgical wire may be in the form of a Kirschner wire or a Cerclage wire.

[0069] The surgical plate may be in the form of a plate for fixing hard tissue, preferably bone tissue.

[0070] The surgical screw may be in the form of a bone screw, i.e., a screw adapted to fix hard tissue, preferably bone tissue.

[0071] The surgical nail may be in the form of a bone nail, i.e., the nail is adapted to fix hard tissue, preferably bone tissue. For example, the surgical nail may be in the form of an intramedullary nail.

[0072] The surgical anchor may be in the form of a bone anchor, i.e., an anchor adapted to fix hard tissue, preferably bone tissue.

[0073] The term "volume providing implant" as used in accordance with the present invention refers to an implant that temporarily fills a cavity in the body for healing or mechanical reasons and supports the gradual healing of natural tissue or bone.

[0074] A second aspect of the present invention relates to a method for manufacturing a medical device, and more particularly, to a method for manufacturing a medical device according to the first aspect of the present invention.

[0075] This method includes the following steps: a) Providing a device body, the device body preferably comprising or consisting of a material susceptible to corrosion or biodegradation, in particular magnesium or a magnesium alloy; b) Generating or causing a shellac coating on the surface of the device body, in particular on the inner and / or outer surface of the device body, the shellac coating having a thickness of from 0.1 μm to 20 μm.

[0076] Preferably, the shellac coating is generated or caused only partially on the surface of the device body, in particular on the inner and / or outer surface.

[0077] Alternatively, the shellac coating is preferably generated or caused on the entire surface of the device body, in particular on the entire inner and / or outer surface.

[0078] Furthermore, the shellac coating may be generated or caused mainly uniformly, i.e., with a constant thickness, on the surface of the device body, in particular on the inner and / or outer surface.

[0079] Alternatively, the shellac coating is preferably generated or caused with varying thicknesses on the surface of the device body, in particular on the inner and / or outer surface.

[0080] Furthermore, step b) is preferably carried out by applying a liquid containing shellac, in particular a solution, to the surface of the apparatus body, in particular the inner and / or outer surfaces. The liquid, in particular the solution, can contain a proportion of shellac of from 0.001% to 20% by weight, in particular from 0.001% to 17% by weight, based on the total weight of the liquid, in particular the solution. Together with the shellac, the liquid, in particular the solution, can contain a solvent selected from the group consisting of alkanols such as ethanol, acetone, chloroform, tetrahydrofuran, ether, cyclic hydrocarbons, universal thinners such as common nitro thinners and combinations thereof, in particular mixtures thereof.

[0081] More preferably, the liquid, in particular the solution, contains ethanol or another alkanol as the solvent. This is particularly advantageous in terms of biocompatibility.

[0082] The term "universal thinner" used according to the present invention refers to a liquid for diluting and / or dissolving alkyd resins and / or nitro lacquers. The general-purpose liquid may contain organic solvents such as ketones, esters, alcohols and / or hydrocarbons.

[0083] Generally, step b) can be carried out by coating techniques.

[0084] For example, step b) may be carried out by immersing the apparatus body in a liquid containing shellac, in particular a solution.

[0085] Alternatively, or in combination, step b) may be carried out by wetting the apparatus body with a liquid containing shellac, preferably a solution.

[0086] Alternatively, or in combination, step b) may be carried out by spraying a liquid containing shellac, preferably a solution, onto the apparatus body.

[0087] Alternatively, or in combination, step b) may be carried out by spraying a liquid, preferably a solution, containing shellac onto the surface of the device body, in particular the inner and / or outer surfaces.

[0088] Furthermore, step b) may be carried out repeatedly. Thus, a multi-layer, for example a two-layer, three-layer or four-layer shellac coating can be produced or generated on the surface of the device body, in particular the inner and / or outer surfaces, and / or possible damage to the shellac coating can be repaired.

[0089] Alternatively, step b) may be carried out only once. Thus, a single-layer shellac coating can be produced or generated on the surface of the device body, in particular the inner and / or outer surfaces.

[0090] Depending on the type of device body, the device body may first be applied onto a carrier system such as a balloon catheter, and then step b) may be carried out. Alternatively, it may also be within the scope of the present invention that step b) is carried out first, and subsequently the shellac-coated device body is applied onto a carrier system such as a balloon catheter.

[0091] Furthermore, the method may include a further step c) of applying a solvent, in particular only a solvent, onto the shellac-coated device body. Thus, damage to the shellac coating can advantageously be repaired or avoided. The solvent may be selected from the group consisting of alkanols such as ethanol, acetone, chloroform, tetrahydrofuran, ethers, cyclic hydrocarbons, universal thinners such as common nitro thinners and combinations thereof, in particular mixtures thereof. Preferably, ethanol or another alkanol is used as the solvent.

[0092] The device body of the medical device can be manufactured, for example, by laser cutting, shaping, laser sintering, stereolithography, or reshaping.

[0093] Further features and advantages of the method, in particular with regard to a medical device, a device body, and a shell coating, are referred to the entire embodiment described under the first aspect of the invention. The features and advantages described in the context of the first aspect of the invention, in particular with regard to a medical device, a device body, and a shell coating, are applied with the necessary modifications to the method according to the second aspect of the invention.

[0094] Further features and advantages of the invention will become apparent from the following description of the preferred embodiments in the form of the drawings, the description of the figures, and the examples, in conjunction with the subject matter of the dependent claims. The individual features can be realized individually or in combination in one embodiment of the invention. The preferred embodiments are merely illustrative and serve for a better understanding of the invention and should not be construed as limiting the invention in any way.

Brief Description of the Drawings

[0095] For a better understanding of what is disclosed, several figures are attached which schematically or diagrammatically show practical examples of embodiments of the invention, merely as non-limiting examples.

[0096]

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Figure 6g

Mode for Carrying Out the Invention

[0097] 1. Manufacturing Example of Medical Device According to the Present Invention 1.1 A solution containing ethanol (basically water-free) with a shellac ratio of 0.5% by weight was prepared. Then, a magnesium stent was immersed in the solution for less than 1 minute. Subsequently, the solution-coated stent was dried to obtain a magnesium stent coated with shellac having a thickness of 0.1 μm to 3 μm.

[0098] 1.2 A solution containing ethanol (basically water-free) with a shellac ratio of 0.5% by weight was prepared. Then, a stent made of magnesium alloy "WE43" was immersed in the solution for less than 1 minute. Subsequently, the solution-coated stent was dried to obtain a stent coated with shellac having a thickness of 0.1 μm to 3 μm.

[0099] 1.3 A solution containing ethanol (basically water-free) with a shellac ratio of 0.5% by weight was prepared. Then, the solution was sprayed onto a magnesium bone replacement scaffold. After drying the solution-sprayed scaffold at 55°C for 15 minutes, a bone replacement scaffold including a shellac coating having a thickness of 0.1 μm to 10 μm was obtained.

[0100] 1.4 A solution containing 0.5 wt% of shellac and ethanol (basically water-free) was prepared. Then, this solution was sprayed onto a bone replacement scaffold made of the magnesium alloy "Resoloy". After the solution-sprayed scaffold was dried at 55 °C for 15 minutes, a bone replacement scaffold with a shellac coating having a thickness of 0.1 μm to 10 μm was obtained.

[0101] 1.5 A solution containing 0.5 wt% of shellac and ethanol (basically water-free) as a solvent was prepared. Then, a magnesium stent was wetted with the solution. After the wetted stent was dried at 55 °C for 15 minutes, a stent with a shellac coating having a thickness of 0.1 μm to 10 μm was obtained.

[0102] 1.7 A solution containing 0.5 wt% of shellac and ethanol (basically water-free) as a solvent was prepared. Then, a stent made of the magnesium alloy "WE43" was wetted with the solution. After a drying step at 55 °C for 15 minutes, a stent with a shellac coating having a thickness of 0.1 μm to 10 μm was obtained.

[0103] Regarding the production examples according to 1.1 to 1.7, the coating step may be repeated, if necessary or desired, in order to cause differences, particularly with respect to the corrosion or biodegradation rate, and thus the hydrogen release rate and / or volume, and / or to repair possible damage to the applied shellac layer. Alternatively, possible coating damage can also be repaired by simply applying ethanol to each of the stent and the bone replacement scaffold.

[0104] 2. Comparison of Corrosion or Biodegradation Rates A wire made of a magnesium alloy "Resoloy" with a thickness of 50 μm was coated with shellac. Subsequently, the coated wire and an uncoated wire made of "Resoloy" with a thickness of 50 μm were immersed in a simulated body fluid solution. In the case of the uncoated wire, immediate corrosion or biodegradation can be observed, while the coated wire showed significantly delayed corrosion or biodegradation and hydrogen evolution, respectively.

[0105] Detailed Description FIG. 1 schematically shows an embodiment of a medical device 10 according to the present invention. The medical device 10 includes a device body 12. The device body 12 preferably comprises or consists of a material susceptible to corrosion or biodegradation, such as magnesium or a magnesium alloy. Further, the medical device 10 includes a shellac coating 14. The device body 12 may be covered only partially or completely (as shown) with the shellac coating 14. Preferably, the shellac coating 14 has a thickness of from 0.1 μm to 20 μm.

[0106] The medical device 10 may, by way of example, be in the form of a scaffold for bone replacement.

[0107] FIG. 2 schematically shows a cross-sectional view of a strut 11 of the medical device 10 of the present invention. The strut 11 is covered with a shellac coating 14. The strut 11 preferably comprises or consists of a material susceptible to corrosion or biodegradation, such as magnesium or a magnesium alloy (e.g., "WE43" or "Resoloy").

[0108] The strut 11 can be completely covered with the shellac coating 14 (as shown). Alternatively, the strut 11 may be covered only partially with the shellac coating 14. This has the additional advantage that differences can be achieved in terms of the corrosion or biodegradation rate and thus the hydrogen evolution during the corrosion or biodegradation of a material susceptible to corrosion or biodegradation.

[0109] Furthermore, the shellac coating 14 preferably has a thickness from 0.1 μm to 20 μm. Further, the shellac coating 14 may have a constant thickness (as shown in the figure) or a varying thickness. A variation in the thickness of the shellac coating 14 is further advantageous because it facilitates the adjustment or generation of portions of the device body 12 where the variation in the thickness of the shellac coating 14 is different in terms of the corrosion or biodegradation rate of the material susceptible to corrosion, and thus in terms of the release of hydrogen during the corrosion or biodegradation process.

[0110] Preferably, the medical device 10 is in the form of a stent.

[0111] Figure 3a shows a further embodiment of the medical device 10 according to the present invention.

[0112] The medical device 10 includes a device body 12 in the form of a scaffold and includes a shellac coating 14. Preferably, the shellac coating 14 has a thickness from 0.1 μm to 20 μm.

[0113] The scaffold 12 preferably comprises or consists of a material susceptible to corrosion or biodegradation such as magnesium or a magnesium alloy (e.g., "WE43" or "Resoloy"). The shellac coating 14 includes portions 14a and 14b having different coating thicknesses. Further, the scaffold 12 includes an end or edge 13a that is at least partially free of the shellac coating 14, i.e., not covered by the shellac coating 14. The end / edge 13a represents the starting point of the corrosion or biodegradation of the material susceptible to corrosion or biodegradation, and thus facilitates the control of the order of corrosion or biodegradation of portions of the scaffold 12. The arrows in Figure 3a represent the direction of the corrosion or biodegradation process. Preferably, the corrosion or biodegradation of the portion 13b of the scaffold 12 occurs last.

[0114] Figure 3b shows the progression of corrosion or biodegradation of the medical device 10 shown in Figure 3a.

[0115] Preferably, the medical device shown in FIGS. 3a and 3b is in the form of a scaffold for replacing hard tissue, particularly bone tissue.

[0116] FIG. 4 shows a further embodiment of the medical device 10 according to the invention.

[0117] The medical device 10 comprises a device body 12 in the form of a plurality of filaments. As shown, the device body 12 can be in the form of filaments arranged in one direction. The filaments preferably comprise or consist of a material that is easily corroded or biodegradable, such as magnesium or a magnesium alloy. Further, the filaments may be in the form of wires, monofilaments, pseudo-monofilaments or multifilaments. Each filament is covered with a shellac coating 14 and each filament includes an end portion that is not covered with the shellac coating 14, i.e., an end portion (i.e., only one end) 13 that is not covered with the shellac coating 14. The end portion 13 of the filament can advantageously serve as a location for the controlled corrosion or biodegradation of the filament and thus the release of hydrogen during the corrosion or biodegradation process. Thus, it is advantageous for the degradation of the medical device 10 to occur slowly from the outside to the inside of the medical device 10. Preferably, the shellac coating 14 has a thickness of from 0.1 μm to 20 μm.

[0118] Preferably, the medical device 10 is in the form of a bone replacement implant, i.e., preferably an implant adapted to fill a bone cavity that may result from a traumatic event such as an accident, infection, or forced surgical removal of bone tissue. Due to the slow degradation of the medical device 10 from the outside to the inside, it can be facilitated that new callus tissue can be generated during the degradation of the old bone tissue. Preferably, the end portion 13 of the filament is adapted to be arranged towards soft tissue, particularly muscle tissue. Thus, the targeted reduction of hydrogen can be promoted and in particular any impairment of tissue bone growth and / or bone regeneration can be avoided.

[0119] Furthermore, the filaments may have different lengths. Further, it may be within the scope of the present invention that the inner filaments do not reach the outer surface of the device body 12 so as to delay corrosion or biodegradation as much as possible.

[0120] FIG. 5 shows a further embodiment of the medical device 10 according to the present invention.

[0121] The medical device 10 comprises a device body 12 in the form of filaments arranged in a spiral. The filaments preferably form the threads (threads) of the medical device 10. Each filament is covered with a shellac coating 14, and only one end of the filament, particularly end 13, is not covered with the shellac coating 14.

[0122] Preferably, the filaments comprise or consist of a material susceptible to corrosion or biodegradation, such as magnesium or a magnesium alloy (e.g., "WE43" or "Resoloy").

[0123] Advantageously, the ends 13 and / or cavities between the coated filaments are adapted to promote a directed reduction of hydrogen during the corrosion or biodegradation of the material susceptible to corrosion or biodegradation.

[0124] Preferably, the medical device 10 shown in FIG. 5 is in the form of a bone screw. In that case, the end 13 of the filament 12 is preferably adapted to be arranged towards soft tissue such as muscle tissue, adipose tissue, or a potential cavity as the abdominal cavity. Thus, a targeted transfer of hydrogen can be promoted during the decomposition of old bone tissue and the formation of new bone tissue (callus). In particular, any adverse effects on the growth and growth of new bone tissue can be advantageously prevented.

[0125] FIG. 6a schematically shows a device body 12 in the form of a bone screw that can be covered with a shellac coating according to the present invention. The bone screw is preferably made of magnesium or a magnesium alloy.

[0126] Figure 6b shows the device body 12 in the form of a bone fixation plate that can be covered with a shellac coating according to the present invention. Preferably, the bone fixation plate is made of magnesium or a magnesium alloy.

[0127] Figure 6c shows the device body 12 in the form of a particulate bone replacement material, where the particles of the bone replacement material can be covered with a shellac coating according to the present invention. The bone replacement material can be made of, for example, a calcium phosphate material such as hydroxyapatite, α-calcium phosphate, or β-tricalcium phosphate.

[0128] Figure 6d shows the device body 12 in the form of a clip, particularly a vascular clip, that can be coated with a shellac coating according to the present invention. Preferably, the clip can be made of magnesium or a magnesium alloy.

[0129] Figure 6e shows the device body 12 in the form of a Kirschner wire for bone joining that can be covered with a shellac coating according to the present invention. The Kirschner wire can be made of magnesium or a magnesium alloy.

[0130] Figure 6f shows the device body 12 in the form of a cerclage wire for bone joining that can be covered with a shellac coating according to the present invention. The cerclage wire can be made of magnesium or a magnesium alloy.

[0131] Figure 6g shows the device body 12 in the form of an intramedullary nail that can be coated with a shellac coating according to the present invention. The intramedullary nail can be made particularly of magnesium or a magnesium alloy. The following items are the elements described in the claims at the time of international filing. [Item 1] An apparatus main body (12) containing a material preferably susceptible to corrosion or biodegradation, and A shellac coating (14) in which the apparatus main body (12) is at least partially covered by the shellac coating (14), comprising The shellac coating (14) has a thickness of 0.1 μm to 20 μm, characterized in that a medical device (10). [Item 2] The medical device (10) according to Item 1, characterized in that the shellac coating (14) has a thickness of 0.5 μm to 15 μm, preferably 1 μm to 10 μm. [Item 3] The medical device (10) according to Item 1 or 2, characterized in that the shellac coating (14) has a varying thickness. [Item 4] The medical device (10) according to any one of Items 1 to 3, characterized in that the thickness of the shellac coating (14) varies from 0.5 μm to 15 μm, preferably from 1 μm to 10 μm. [Item 5] The medical device (10) according to any one of Items 1 to 4, characterized in that the apparatus main body (12) is only partially covered by the shellac coating (14). [Item 6] The medical device (10) according to any one of Items 1 to 5, characterized in that the shellac coating (14) has a ratio of 10 - 10 wt% to 99 wt%, particularly 0.001 wt% to 20 wt%, preferably 0.01 wt% to 10 wt% based on the total weight of the medical device (10). [Item 7] The medical device (10) according to any one of Items 1 to 6, characterized in that the shellac coating (14) is a wax containing a shellac coating. [Item 8] The medical device (10) according to any one of Items 1 to 6, characterized in that the shellac coating (14) is a shellac coating not containing wax. [Item 9] The device body (12) contains voids, in particular pores, and preferably, the voids, in particular pores, are at least partially filled with the shellac coating (14), and the medical device (10) according to any one of items 1 to 8 is characterized in that. [Item 10] The medical device (10) according to any one of items 1 to 9, characterized in that the mechanically separated parts and / or electrically insulated parts of the device body (12) are at least partially covered with the shellac coating (14). [Item 11] The medical device (10) according to any one of items 1 to 10, characterized in that the device body (12) includes a plurality of filaments, and each filament is at least partially covered with the shellac coating (14). [Item 12] The medical device (10) according to any one of items 1 to 11, characterized in that the material susceptible to corrosion or biodegradation is magnesium. [Item 13] The medical device (10) according to any one of items 1 to 11, characterized in that the material susceptible to corrosion or biodegradation is a magnesium alloy. [Item 14] The medical implant is, in particular, an implant selected from the group consisting of surgical implants, stents, stent grafts, artificial blood vessels, vascular accesses, wound dressings, sutures, surgical meshes, surgical wires, surgical plates, surgical screws, surgical nails, surgical anchors, surgical clips, wound closures, volumes for providing implants for hard tissues, preferably bone tissues, connectors, medical tubes, bags, medical needles and probes, and is characterized in that the medical device (10) according to any one of items 1 to 13. [Item 15] In particular, a method for manufacturing the medical device (10) according to any one of items 1 to 14, a) providing the device body (12), wherein the device body (12) preferably comprises a material susceptible to corrosion or biodegradation; b) forming the shellac coating (14) on the surface of the device body (12), in particular on the inner surface and / or outer surface of the device body (12), wherein the coating (14) has a thickness of 0.1 μm to 20 μm.

Claims

1. An apparatus body (12) comprising a material susceptible to corrosion or biodegradation, and a shellac coating (14) at least partially covering the apparatus body (12), a medical device (10) comprising: the shellac coating (14) having a thickness of from 0.1 μm to 20 μm, the material susceptible to corrosion or biodegradation being magnesium or a magnesium alloy, the shellac coating (14) including portions having different coating thicknesses, The medical device (10), characterized in that the medical device is a bone replacement implant.

2. The medical device (10) according to claim 1, characterized in that the shellac coating (14) has a thickness of from 0.5 μm to 15 μm.

3. The medical device (10) according to claim 1 or 2, characterized in that the thickness of the shellac coating (14) varies from 0.5 μm to 15 μm.

4. The medical device (10) according to any one of claims 1 to 3, characterized in that the apparatus body (12) is only partially covered with the shellac coating (14).

5. The shellac coating (14) has a ratio of 10 -10 to 99% by weight, based on the total weight of the medical device (10), the medical device (10) according to any one of claims 1 to 4.

6. The medical device (10) according to any one of claims 1 to 5, characterized in that the shellac coating (14) is a wax including a shellac coating.

7. The medical device (10) according to any one of claims 1 to 5, characterized in that the shellac coating (14) is a shellac coating without wax.

8. The medical device (10) according to any one of claims 1 to 7, characterized in that the apparatus body (12) includes voids, and the voids are at least partially filled with the shellac coating (14).

9. The medical device (10) according to any one of claims 1 to 8, characterized in that mechanically separated portions and / or electrically insulated portions of the apparatus body (12) are at least partially covered with the shellac coating (14).

10. The medical device (10) according to any one of claims 1 to 9, characterized in that the apparatus body (12) includes a plurality of filaments, and each filament is at least partially covered with the shellac coating (14).

11. A method of manufacturing a medical device (10) according to any one of claims 1 to 10, a) providing the device body (12), wherein the device body (12) comprises a material susceptible to corrosion or biodegradation, and the material susceptible to corrosion or biodegradation is magnesium or a magnesium alloy; b) forming the shellac coating (14) on the surface of the device body (12), wherein the coating (14) has a thickness of 0.1 μm to 20 μm, and the shellac coating is formed with a varying thickness on the surface of the device body.

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