Drug – bio-affecting and body treating compositions – Solid synthetic organic polymer as designated organic active... – Aftertreated polymer
Reexamination Certificate
1998-06-26
2002-04-09
Webman, Edward J. (Department: 1617)
Drug, bio-affecting and body treating compositions
Solid synthetic organic polymer as designated organic active...
Aftertreated polymer
C427S508000, C427S340000
Reexamination Certificate
active
06368587
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for the bioactive coating of the surface of substrates, preferably plastic (or polymer) substrates using a macroinitiator. An important property of the coatings applied in accordance with the present invention is their high compatibility in contact with body fluids and tissue, especially with blood. Depending on the functionality of the coating monomers and on the molar ratio of certain functional groups in the coating, the surfaces, moreover, repel bacteria and inhibit cell proliferation, or repel bacteria and promote cell proliferation. The present invention additionally relates to products having surfaces coated in this way for use for medical or biotechnical purposes or in the hygiene sector.
2. Description of the Background
The colonization and multiplication of bacteria on surfaces is a phenomenon which is generally undesirable and is frequently associated with adverse consequences. For instance, in the drinking water and beverage industry bacterial populations may lead to a reduction in product quality and endanger health. Bacteria on or in packaging frequently bring about the decay of foods or even cause consumer infections. In biotechnical plaints that operate under sterile conditions, bacteria may be introduced with raw materials or may remain in all parts of the plant if sterilization is inadequate. By adhesion, sections of the bacterial population may escape the normal liquid exchange entailed in rising and cleaning and multiply within the system.
Bacterial colonies are also known in water treatment plants (for example, for membrane desalination) as well as in containers which have been filled with dissolved or liquid, undiluted organic substances offering advantageous conditions for bacterial populations. Such microbial colonization can, to a considerable extent, lead to the blocking and/or corrosive destruction of the plant.
Particular importance is attached to protecting against bacterial adhesion and propagation in nutrition, in human care, especially in the care of the elderly, and in medicine. In the case of large-scale outlets serving food or drinks, there are considerable risks especially when, rather than using disposable tableware with the attendant problem of wastage, reusable tableware is employed that is inadequately cleaned. Also known is the harmful propagation of bacteria in hoses and pipes which conduct foods, as well as their multiplication in storage containers and in textiles in a hot and damp environment, for example, in swimming baths. Facilities of this kind are preferred habitats for bacteria, as are certain surfaces in areas through which many people pass, for example in public transport vehicles, hospitals, telephone boxes and schools and especially in public toilets.
In the care of the sick and elderly, the often reduced defenses of those affected necessitate careful measures to counter infections, especially on intensive care wards and in the case of care at home.
Particular care is required in the use of medical articles and instruments in the case of medical investigations, treatments and interventions, especially when such instruments or articles come into contact with living tissue or with body fluids. In the case of long-term or permanent contact, especially in the case of implants, catheters, stents, cardiac valves and pacemakers, bacterial contamination can become a life-threatening risk to the patient. Diverse attempts have already been made to suppress the colonization and propagation of bacteria on surfaces. In J. Microbiol. Chemoth. 31 (1993), 261-271 S. E. Tebbs and T. S. J. Elliott describe paintlike coatings with quaternary ammonium salts as antimicrobial components. It is known that these salts are dissolved out of the coating material by water, by aqueous or by other polar media and by body fluids, and that their action is therefore short-lived. This applies equally to the incorporation of silver salts in coatings, as described in WO 92/18098.
T. Ouchi and Y. Ohya in. Progr. Polym. Sci. 20 (1995) 211 ff. describe the immobilization of bactericidal active substances on polymer surfaces by means of covalent bonding or ionic interaction. In such cases, the microbicidal actions are frequently reduced markedly relative to the pure active substance. Heteropolar bonds often prove to be of insufficient stability. Furthermore, the killing of the microbes leads in general to unwanted deposits on the surfaces, which mask the subsequent bactericidal action and form the basis for later bacterial colonization.
W. Kohnen et al. in ZBI. batch. sup. 26, Gustav Fischer Verlag, Stuttgart-Jena-New York, 1994, pages 408 to 41 0 report that the adhesion of
Staphylococcus epidermidis
on a polyurethane film is reduced if the film is pretreated by glow discharge in the presence of oxygen and is then grafted with acrylic acid.
The literature also describes the grafting of monomers onto substrates to which a peroxide-containing polymer has been applied beforehand as macroinitiator. In these systems, the photolytically or thermally cleavable groups are located in the polymer framework (DE 30 44 531, EP 0 370 477). In cleaving these groups to form free radicals, the polymer framework of the macroinitiator is broken down and thus loses its stability. Such a polymer cannot be applied to other substrates to form a permanent interpenetrating network (IPN), since the cleavage of the abovementioned groups forms small polymer fragments which diffuse out of the substrate network.
DE-A 22 42 818 describes the preparation of polymers containing peroxydiester groups in side chains, but does not indicate any specific use therefor.
As noted, it is important, when medical articles and instruments are used in medical investigations, treatments and interventions, that bacterial contamination of these articles and instruments is prevented. In the case of some of these articles and instruments, which come into medium- or long-term contact with living tissue or body fluids, moreover, the adhesion and propagation of endogenous cells is extremely undesirable. Thus cell colonization in the case of catheters applied intra-corporeally in the medium term is just as harmful as in the case of cardiac valves or stents which are implanted in the long term.
Furthermore, the transparency of intraocular lenses may experience a continuous decrease as a result of cell colonization after implantation. There is a range of processes aimed at avoiding cell colonization, for example by incorporating certain metals or metal salts into the mount of the intraocular lens, although the effect is usually incomplete and not durable. WO 94/16648, too, describes a process which is intended to prevent the proliferation of cells on the surface of implanted ocular lenses made from polymer material.
According to EP 0 431 213, polymers are to be furnished with cell-repelling properties by rendering their surface hydrophilic using strong mineral acids. The subsequent chemical modification of polymer surfaces, however, is in most cases not uniform. In general, there remain sites which have been treated not at all or not sufficiently and which constitute starting points for cell colonization. In addition, the cell-repelling properties of the surfaces treated in this way are in many cases not durable.
On the other hand, certain utilities require articles having surfaces which are repellent to bacteria but which promote cell colonization. This applies, for example, to a range of instruments for medical investigations, treatments and interventions, and also to some prostheses which are intended to grow into the tissue into which they have been implanted. Such instruments and prostheses, for example artificial hip joints or teeth, consist frequently of polymers or of other materials with a polymer coating, such as metals.
Finally, materials for instruments and devices which come into contact with body fluids, such as blood or lymph, or with tissue, must be compatible with their foreign environment. Blood compat
Anders Christine
Götz by Kathrin
Jacobasch by Lutz
Jacobasch by Margareta Ute Dagmar
Jacobasch by Susanne
Huels Aktiengesellschaft
Webman Edward J.
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