the following description describes the invention more closely in an embodiment : a porcine heart valve is used as an example of a collagen tissue of animal origin , which is to be used as an implant in a human body . this is prepared , de - cellularised and glutaraldehyde - fixed after removal from the donor animal for stabilisation in a conventional manner . in this case , the valve is brought into a glutaraldehyde solution of between 0 . 1 and 0 . 4 % and fixed in a flowing solution at low pressures of 3 to 6 mm hg over 24 to 48 hours . the porcine heart valve prepared in this manner is then slowly dried under a vacuum and with the supply of temperature and thus completely dehydrated . thereafter , a plasma treatment of the porcine heart valve is carried out in a treatment chamber . for this purpose , the treatment chamber is completely evacuated and oxygen then introduced . a plasma is ignited by inputting a high - frequency electromagnetic field of , for example , 40 khz or 13 . 56 mhz or by excitation with microwaves . the oxygen gas present in the treatment chamber is excited and radicalised by the energy supply connected therewith . this plasma gas acts on the hydrocarbon groups c x h y on the surface of the glutaraldehyde - fixed implant according to the following reaction equation : c x h y +( x + y / 4 ) o 2 → x co 2 + y / 2h 2 o . as can be seen , hydrocarbons on the implant surface , such as , for example , acetaldehydes are converted into the comparatively harmless chemical compounds carbon dioxide and water , which can be easily removed from the implant surface . the above plasma treatment is then continued to apply the metal - containing coating on the implant surface . for this purpose , a gaseous precursor is fed into the coating chamber and is separated under the influence of the plasma energy into its atomic components . the ions thus being produced settle on the surface . typically , titanium is primarily applied as the metal - containing coating with the aid of the pacvd method . the method as such is described in detail , moreover , in ep 0 897 997 b1 using the example of coating a plastics material substrate . the reactor pressure both for the pre - treatment and for the coating is between 0 . 1 and 1030 mbar . when applying a plasma , the pressure should ideally be & gt ; 50 mbar . for the pre - treatment , the working gas ( for example oxygen ) is introduced into the reactor at a gas volume flow of 0 . 04 nl / min . after stabilisation of the end pressure to about 1 mbar , the capacitive plasma input takes place at a power of 20 w for a duration of 60 sec . the gas supply is then interrupted and the reactor chamber completely evacuated . the carrier gas ( hydrogen ) is guided for the following coating at a gas volume flow of 0 . 09 nl / min over the precursor ti [ n ( ch 3 ) 2 ] 4 and introduced into the coating chamber . the coating duration is about 300 sec . with an adjusted plasma power of 20 w . the gas supply is then stopped again and the coating chamber ventilated . after this vacuum treatment for plasma loading and coating the porcine heart valves , these are again placed in liquid , so they regain their original consistency owing to the liquid supplied .
a method for treating glutardialdehyde - stabilized biological tissue of animal or human origin , such as porcine , bovine pericardium or human cadaver heart valves , provides a physical plasma treatment of the , in particular , collagen tissue for increasing the biocompatibility , cell colonization and durability thereof .