Housing for a medical implant with a titanium-based germ-inhibiting coating

Abstract

Medical implant (1), comprising: a housing (2) with a metallic surface (20), characterized in that a nanostructure made of titanium is applied to the surface (20), which nanostructure has a plurality of titanium nanocolumns (21) arranged next to one another and projecting from the surface (20).

Description

The present invention relates to a medical implant, in particular an active medical implant, i.e. an implant which has its own energy supply. Such an implant has a housing in which components of the implant are arranged, such as an electronic module and a power supply provided for this purpose, in particular in the form of a battery.Infections in connection with implants regularly represent a clinical risk. Bacteria can colonize and proliferate on surfaces of implants. Uncontrolled bacterial growth can lead to the formation of biofilms, which make antibiotic treatments more difficult or even ineffective. Infected implants may result in correspondingly severe complications and require revision interventions or long antibacterial treatments, which are associated with additional risks. From an economic point of view, the treatment costs of infections by implants can exceed the costs of the initial implantation by a multiple. Therefore, the development of bacterial repellent surfaces which inhibit or prevent bacterial colonization and growth is highly desirable.Various strategies for preventing the aforementioned bacterial colonization are known in the art, including coatings of surfaces with antibiotics, directly or embedded in carrier layers.However, the use of medicines may involve other problems. Thus, excessive and repeated use of antibiotics can lead to the development of resistant bacterial strains. Moreover, said medicaments are released over time and are accordingly only effective for limited periods of time. As soon as the release of active substance is exhausted, the surface no longer offers protection against bacteria. Moreover, drugs can fundamentally produce undesirable side effects.On the basis of this, the object of the invention is to provide a medical implant which reduces the risk of bacterially caused infection (e.g. pocket infection) without releasing an antibiotic medicament.This object is achieved by a medical implant having the features of claim 1. Advantageous embodiments of the invention are described below.According to claim 1, a medical implant, in particular an active medical implant, is disclosed, comprising:a housing having a metallic, outwardly facing surface, wherein, according to the invention, a nanostructure made of titanium is applied to the surface, said nanostructure having a multiplicity of titanium nanocolumns arranged side by side and protruding from the surface.Preferably, the nanocolumns form an outer surface of the finished implant. Particularly preferably, the titanium nanocolumns cover an entire surface area of the finished implant, which forms an outwardly exposed surface of the implant. The implant can have a header for connecting at least one electrode. The header may be fixed to a surface portion of the housing and may conceal the same. This surface portion may be free of said nanostructure.According to a preferred embodiment of the invention, said surface of the housing comprises titanium or a titanium alloy. Said titanium nanocolumns are then applied to this surface.The medical implant can be an implantable pulse generator. In particular, the medical implant can be an implantable cardiac pacemaker, an implantable cardioverter-defibrillator or an implantable heart monitor. In particular, however, the invention can be applied to all conceivable implants having a titanium surface.According to one aspect of the invention, the titanium nanocolumns according to the invention are applied to the surface of the housing of the implant by a coating method, in particular a magnetron sputtering method.It is found in particular that the coating according to the invention, i.e. the titanium nanocolumns, has a germ-inhibiting effect. Antibacterial behavior is shown in particular in the case of the Gram-negative bacterium E. coli. In this regard, the titanium nanocolumns provide for mechanical destruction of the bacterial cell walls.Embodiments of the invention and further features and advantages of the invention are to be explained below with reference to the figures. The following are shown: FIG. 1 shows a schematic illustration of a housing of a medical implant according to the invention during the production of a nanostructure from titanium nanocolumns on the surface of the housing, and FIG. 2 shows a shadow effect during sputtering.FIG. 1 shows a housing 2 of an embodiment of an implant 1 according to the invention during the production of titanium nanocolumns 21 on an outwardly facing surface 20 of the housing 2 of the implant 1.The titanium nanocolumns 21 can be made in the form of a titanium film by magnetron sputtering, for example, with an AJA ATC-2200V sputtering deposition system 100 which may be equipped with a loadlock. The housing 2 to be coated can be positioned on a carrier 103 which is rotatable about a e.g. vertical axis of rotation z. For producing the columnar Ti nanostructures, an obliquely incident source 101 fixed at an angle of β≈88° and a confocal incident source 102 positioned at an angle of α≈27° with respect to the normal of the carrier 103 or of the housing surface 20 to be coated can be used. During the deposition process, the oblique angle of inclination of the incident particle flow induces a ballistic shading effect (see FIG. 2 ). In this way, column-shaped nanostructures can be achieved in a stationary carrier 103. In the case of a carrier rotating about the z-axis (e.g. in the case of a rotation about the z-axis at 25 revolutions per minute), vertical titanium nanocolumns 21 can be constructed in particular.The Ti nanostructures 21 can be deposited in particular by magnetron sputtering from a 4-inch Ti metal target (purity 99.99%) in a sputtering system 100 at a base pressure below 5.9×10 -8 Torr. The distance between target and surface 20 may be about 12 cm and 15 cm, respectively, for source 101 and source 102. The nanostructure may be prepared at 5 mTorr Ar pressure and 200 W (DC) power for 240 minutes. Typical Ti nanocolumns may have a height H of about 480 nm and a width D of about 30 nm.The present invention is advantageous because the implant produced directly has the desired antibacterial property and no further products, in particular medicaments, have to be used in order to produce such an effect.

Claims

Medical implant (1) comprising: a housing (2) with a metallic surface (20), characterized in that a nanostructure made of titanium is applied to the surface (20), said nanostructure comprising a plurality of titanium nanocolumns (21) arranged side by side and protruding from the surface (20).

Images