CA2226133A1 - Bioactive surface coating - Google Patents

Abstract

Disclosed is a process for making a surface of a substrate biocompatible, which comprises subjecting at least one monomer of the general formula: R-(A)a, (in which R is a mono- or diolefinically unsaturated organic radical, having the valency a, A is a carboxyl group -COOH, a sulfuric acid group -OSO2OH, a sulfonic acid group -SO3H, a phosphoric acid group -OPO(OH)2, a phosphonic acid group -PO(OH)2, a phosphorous acid group -OP(OH)2, a phenolic hydroxyl group or a salt or an ester thereof and a is an integer from 1 to 6) to graft-polymerization under radiative induction onto an activated surface of the substrate, with the proviso that when A is a carboxyl group -COOH or a salt or an ester thereof, either the monomer contains at least one further different radical A is used together with at least one further monomer in which A is other than a carboxyl group or a salt or ester thereof. The process is suitable for producing medical or biotechnical articles, storage containers or packaging.

Description

Bioactive surface coatinq The invention relates to a coating process of a surface of a substrate, preferably of a plastic (or polymer) substrate, by graft polymerization. An important property of the coating applied by the process of the invention is high compatibility with a body fluid and tissue. Depending on the functionality of a coating monomer and/or on a molar ratio of certain functional groups within the coating, the surface additionally acquires either antibacterial and cell proliferation inhibiting properties, or antibacterial and cell proliferation promoting properties. The invention also relates to an article with a surface coated by the process of the invention and to the use of such article for medical or biotechnical purposes.
The colonization and multiplication of bacteria on a surface is a phenomenon which in general is unwanted and which is frequently associated with adverse consequences. For instance, in the drinking water and beverage industry, bacterial populations can lead to a reduction in quality and can pose a hazard to health. Bacteria on or in packaging frequently brings about the decay of foods and can cause infections in consumers. In biotechnical plants that are to be operated under sterile conditions, bacteria alien to a system constitute a considerable processing risk. Such bacteria may be introduced with raw materials or may remain in any parts of the plant if sterilization is inadequate. By means of adhesion, portions of a bacterial population may escape the normal liquid exchange entailed in rinsing and cleaning and can then multiply within the system.

O.Z. 5192 Colonies of bacteria are also known in water treatment plants (for example for membrane desalination) or else in containers which are filled with dissolved or liquid undiluted organic substances and which provide suitable conditions for supporting bacterial populations. In general, significant microbial colonization in a water treatment plant can, to a considerable extent, lead to the blocking and/or corrosive destruction of the plant.
Particular importance is attached to protecting against bacteria adhesion and propagation in the areas of nutrition, human care, especially care of the elderly, and medicine. In the case of large-scale outlets serving food or drinks, there are considerable risks especially when, as an alternative to disposable tableware with its attendant problem of wastage, reusable tableware is employed but is not adequately cleaned. Also known is the harmful propagation of bacteria in hoses and pipes which conduct foods, as is their multiplication in storage containers, in textiles and in hot and damp environments, for example in swimming baths.
Facilities such as these are preferred habitats for bacteria, as are certain surfaces in areas with a high level of public traffic, 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 at home.
Particular care is required in the use of medical articles and instruments in the case of medical investi-O.Z. 519223443-625 gations, 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 a 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. Elliot 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 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 in many cases markedly reduced relative to the pure active substance. Heteropolar bonds often prove to be of insufficient stability. Furthermore, the killing of microbes by this approach in general leads to unwanted deposits on the surfaces, which mask further bactericidal action and form a basis for subsequent bacterial colonization.
W. Kohnen et al., in ZBl. Bakt. Suppl. 26, Gustav Fischer Verlag, Stuttgart-Jena-New York, 1994, pages 408 to 410, report that adhesion of Staphylococcus epidermidis to a o.z. 5192 23443-62s polyurethane film is reduced if the film is pretreated by glow discharge in the presence of oxygen and is then grafted with acrylic acid.
As mentioned, when medical articles and instruments are used in medical investigations, treatments and inter-ventions, it is important to prevent bacterial contamination of these articles and instruments. In the case of some of these articles and instruments, which come into medium- or long-term contact with living tissue or body fluids, adhesion and propagation of endogenous cells is extremely undesirable.
Thus cell colonization in the case of catheters applied intracorporally 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, transparency of intraocular lenses after implantation may undergo a continuous deterioration as a result of cell colonization. There is a range of processes aimed at avoiding cell colonization, for example incorporating certain metals or metal salts into the mount of the intraocular lens, although the incorporation lS usually incomplete and not durable. For example, WO 94/16648 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 can be furnished with cell-repelling properties by rendering their surface hydrophilic with strong mineral acids. The subsequent chemical modification of polymer surfaces, however, is in most cases not uniform. In general, there remain sites which o.z. 5192 either remain untreated or are not sufficiently treated and which constitute starting points for cell colonization. In addition, the cell-repelling properties of surfaces treated in this way in many cases do not last.
On the other hand, certain applications require articles having surfaces which are repellent to bacteria but which promote cell colonization. This applies, for example, to a variety of instruments for medical investigations, treatments and interventions and also to many 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, often consist of polymer-clad materials such as titanium.
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 environ-ment. Blood compatibility in particular is an important desired property. The materials must therefore as far as possible have pronounced antithrombic properties.
There is therefore a variety of partially mutually exclusive requirements with respect to the bioactive properties of the surface of polymers which are intended for medical uses. They are required always to be antibacterial and compatible with body fluids and tissue but should have an alternatively cell proliferation inhibiting or promoting action.
A major object of the present invention is to develop an improved process for coating a surface of a substrate to make the surface antibacterial and compatible o.Z. 5192 with a body fluid and tissue as well as cell proliferation-inhibiting or promoting, without thereby altering the mechanical properties of the treated substrate or giving rise to any other major disadvantages.
It has surprisingly been found that a surface of a substrate, especially a polymeric substrate can be made to possess those properties mentioned above by coating according to a process described hereinunder.
According to the process, at least one monomer of the general formula (I):
R-(A)a (I) (in which R is a mono- or diolefinically unsaturated organic radical, for example a hydrocarbon radical, having the valency a, A is a carboxyl group -COOH, a sulfuric acid group -OSO20H, a sulfonic acid group -SO3H, a phosphoric acid group -OPO(OH)2, a phosphonic acid group -PO(OH)2, phosphorous acid group -OP(OH)2, a phenolic hydroxyl group, or a salt or an ester of one of these groups, and a is an integer from 1 to 6), is subjected to graft-polymerization under radiative induction on to an activated substrate surface, with the proviso that when A is a carboxyl group -COOH or a salt or an ester of the carboxyl group, the monomer contains at least one further radical A which is a different one of those specified for A or is used together with at least one further monomer of the formula (I) in which A is a different one of those specified for A.

O.Z. 5192 Among the salts of the groups specified for A, preferred are physiologically acceptable salts including alkali metal salts and, in particular, sodium salts.
The common feature of the monomers of formula (I) is that they have one or two olefinic double bonds and also at least one acidic group or a particular derivative, namely a salt or an ester, of an acidic group.
Coatings produced on various substrates by a plasma-induced graft polymerization of functional monomers are known, for example, from B. Lassen et al., Clinical Materials 11 (1992), 99-103, and have been investigated for biocompati-bility. No activating pretreatment is mentioned in this literature.
Moreover, plasma is not an optimal polymerization initiator. H. Yasuda refers accordingly in J. Polym. Sci.:
Macromolecular Review, Vol. 16 (1981), 199-293, to the undefined and uncontrollable chemistry of plasma polymer-ization. This may be acceptable for some purposes, but is problematic for medical and biotechnical applications, since reproducible coatings of consistently high quality are required.
Surprisingly, the antibacterial properties of the surface coated in accordance with the invention with a carboxyl, carboxylate or carboxylic ester group-containing monomer of formula (I) together with another monomer of formula (I) are markedly more pronounced than is the case with the modification with acrylic acid alone, according to W. Kohnen et al., in ZBl. Bakt. Suppl. 26, Gustav Fischer Verlag, Stuttgart-Jena-New York, 1994, pages 408 to 410, under O.Z. 5192 comparable conditions.
A surface coated in accordance with the process of the invention displays a remarkable combination of advan-tageous properties and therefore outstanding physiological compatibility. It is, in particular, highly compatible with blood and reduces the adhesion and propagation of bacteria to a high extent even over a prolonged period. Bacteria affected by this action include Staphylococcus aureus, Staphylococcus epidermidis, StrePtococcus pyoqenes, Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli. At the same time there is also inhibition of the proliferation of cells in most cases, for example of fibroblasts and endothelial cells, such as human umbilical cord cells. The particular conditions under which a coating has an antibacterial but cell proliferation-promoting action are explained later. The surface of a substrate coated in accordance with the process of the invention is free from migratable and/or extractable monomer and oligomer components. Unwanted side effects resulting from released exogenous substrates or from dead bacteria are avoided from the outset.
In the process according to the invention, the substrate surface is first activated, as described in more detail below, and then is coated under the action of radiation, such as W light by non-aggressive graft polymerization or graft copolymerization.

1. The mo~nm~r~
In the formula (I), R is a mono- or diolefinically unsaturated organic radical. Preferably, the organic radical O.Z. 5192 R is a hydrocarbon radical having 2 to 12 carbon atoms which may have a substituent other than an acidic group and not having negative effects upon living bodies, such as C1_4 alkyl and -NH2. The hydrocarbon radical may preferably be one represented by the formula CnH2n_q_x (in which n, q and x are defined hereinunder), (C6H6-b-C-d~cnH2n-l-q-x) (in which b~
c, d, n, q and x are as defined hereinunder), R1 HC=CR1 -R2 _ (in which Rl and R2 are as defined hereinunder) or R5HC=CRl -R2 (in which R5, Rl and R2 are as defined hereinunder).
In the graft (co)polymerization, the monomer is preferably a mixture of (1) a monomer of the formula (I) having one or two carboxyl groups or a salt or ester thereof and (2) a monomer of the formula (I) having one or two sulfonic acid groups or a salt or ester thereof. More preferably, such a mixture may be a mixture of monomers of the general formulae (II) and (III):
(CnH2n_q_x)(COOR )x (II) (CnH2n_q_x)(S03R )x (III).
In the formulae, which are within the scope of the formula (I), B independently at each occurrence is an integer from 2 to 6;
_ independently at each occurrence is 1 or 2;
independently at each occurrence is 0 or 2; and Rl, independently at each occurrence, is hydrogen, an equivalent of a metal ion, preferably an alkali metal ion, a residue of an aliphatic, cycloaliphatic or araliphatic alcohol, preferably of an alkanol having 1 to 8 carbon atoms, O.Z. 5192 preferably having 1 to 4 carbon atoms, a residue of a cycloalkanol having 5 to 12 carbon atoms, a residue of an arylalkanol having 7 to 10 carbon atoms or a residue of an alkanol having one or more of oxygen or nitrogen atoms in its chain and up to 13 carbon atoms, such as -(CH2-CH2-O)d-H, -(CH2-CH(CH3)-O)d-H, -(CH2-CH2-CH2-O)d-H or -(CH2)d-NH2_e(R2)e, where R2 is -CH3 or -C2H5, d is 1, 2, 3 or 4 and e is 0, 1 or 2.
In accordance with the definitions given, the radical (CnH2n_q_x)~ independently at each occurrence is a straight-chain or branched monovalent alkenyl radical (q=0, x=1) or alkadienyl radical (q=2, x=1) or a divalent alkenylene radical (q=0, x=2) or alkadienylene radical (q=2, x=2).
Instead of two monomers of formula (II) and (III), it is also possible to employ only one monomer which includes both -COOR1 and -SO3R1 groups in the same molecule.
In addition, another group of preferred monomers of the formula (I) are benzene-derived monomers of the general formula:
(C6H6-b-c-d)(B)v(R3)c(oH)d~ namely ~ ~ (~E~d ~R3 in which:
B independently at each occurrence is a straight-chain o.Z. 5192 or branched radical of the formula (CnH2n_1_q_x)_ (COOR )x or (cnH2n-l-q-x)(so3Rl)xt where R
and _ are as defined above;
R3 independently at each occurrence is a monovalent substituent such as C1_4 alkyl, -NH2, - COOH, -SO3H, -OSO3H, -OPO(OH)2, -PO(OH)2, -OP(OH)2, -OPO(O-)OCH2-CH2 N (CH3)3, -PO(O )O-CH2-CH2-N+(CH3)3, -OP(O-)-OCH2-CH2-N+(CH3)3 or optionally a salt, especially an alkali metal salt, or an ester of the acid group;
- 10 b is 1, 2 or 3;
c is 0, 1, 2 or 3; and d is 0, 1, 2 or 3;
with the proviso that b + c + _ < 6, preferably c 4.
It is of course also possible to employ any suitable mixture of monomers of the general formulae (II), (III) and (IV) for the process according to the invention.
Other suitable monomers corresponding to formula (I) can contain neutral or acidic sulfuric esters and salts of the latter; sulfonic acids, their salts and esters; phosphonic acids, their neutral or acidic salts, neutral or acidic esters and salts of the acidic esters; phosphoric esters, their neutral or acidic salts, neutral or acidic esters and salts of the acidic esters; and phosphorous acids, their neutral or acidic salts, neutral or acidic esters and salts of the acidic esters. These monomers too can be used as a mixture with one another and/or with the monomers of the general formulae (II), (III) and (IV) for the process according to the invention.
Finally, mention may also be made of phenols of O.Z. 5192 formula (I) having a valency (or basicity) of from 1 to 3, and also their salts, as suitable monomers. These too are optionally employed as a mixture with one another and/or with the abovementioned monomers.
For the process according to the invention it has proved worthwhile to use a combination of monomers of formulae (I) to (IV) which leads to a coating which has both a carboxyl and/or carboxylate group and a sulfonic acid and/or sulfonate group. From the standpoint of compatibility with regard to lo the groups, there are three possible two-way combinations, namely carboxyl and sulfonic acid groups, carboxyl and sulfonate groups, and carboxylate and sulfonate groups, and also two three-way combinations, namely carboxyl, carboxylate and sulfonate groups, and carboxyl, sulfoacid and sulfonate groups. All of these combinations constitute useful monomers for the process according to the invention. It is of course also possible to employ monomers whose functional groups are altered after the graft polymerization. Thus it is possible, for example, to transform an acrylamide structural unit subsequently, by hydroysis in an acidic medium, into the acrylic acid structural unit. It is also possible to convert carboxyl and sulfonic acid groups by neutralization (for example in phosphate buffers), and carboxylic ester and sulfonic ester groups by hydrolysis, into carboxylate and sulfonate groups, respectively.
In the abovementioned combination, the molar ratio of carboxyl and/or carboxylate groups to sulfonic acid and/or sulfonate groups in the coating can fluctuate within wide limits. Particularly pronounced cell proliferation inhibiting O.Z. 5192 properties are obtained when the ratio is from 0.2 to 3, preferably from 0.4 to 3 and, in particular, from 0.4 to 2.
The coated surface exhibits, in a remarkable manner, antibacterial but cell proliferation promoting properties when the molar ratio is from 2 to 10, preferably from 3 to 10 and, in particular, from 3 to 5. A coating is cell proliferation promoting for the purposes of the invention when the adhesion and multiplication of mammalian cells is improved by the coating, in comparison with the uncoated surface, or at least is less strongly impaired than the adhesion and multiplication of bacteria.
Of the suitable monomers of the general formulae (I) to (IV) which contain one or more identical or different radicals A in the molecule, examples include:
acrylic acid, sodium acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-(2'-hydroxyethoxy)ethyl acrylate, 2-hydroxy-1-methylethyl acrylate, 2-N,N-dimethylaminoethyl acrylate, methacrylic acid, sodium methacrylate, n-propyl methacrylate, 2-hydroxyethyl methacrylate, 2-(2'-hydroxyethoxy)ethyl methacrylate, 2-hydroxy-1-methylethyl methacrylate, 2-N,N-dimethylaminoethyl methacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, 4-vinylsalicyclic acid, itaconic acid, vinylacetic acid, cinnamic acid, 4-vinylbenzoic acid, 2-vinylbenzoic acid, sorbic acid, caffeic acid, maleic acid, methylmaleic acid, crotonic acid, isocrotonic acid, fumaric acid, dimethylfumaric acid, methylfumaric acid, dihydroxymaleic acid, allylacetic acid;

O.Z. 5192 sodium allyl sulfate, sodium allylsulfonate, sodium methallyl sulfate, sodium methallylsulfonate, sodium vinylsulfonate, 2-hydroxyethyl vinylsulfonate, 4-vinylbenzenesulfonic acid, sodium styrenesulfonate, sodium vinyltoluenesulfonate;
2-butene-1,4-diol diphosphate (i.e., 1,3-butadiene-1,4-diol diphosphate), 2-butene-1,4-diol diphosphonate, the disodium salts of these phosphates or phosphonates, diallyl phosphite (meth)acryloyloxyethylphosphoryl-chlorine;
2-vinylphenol, 2-allylhydroquinone, 4-vinylresorcinol, m-hydroxystyrene, p-hydroxystyrene and carboxyl-vinyl-benzene sulfonic acid.
Examples of the monomers of the formula (I) having only one or more carboxyl groups and their derivatives, which may not be used alone but may be used together with one or more other monomers of the formula (I), include acrylic acid, methacrylic acid, itaconic acid, vinylacetic acid, c; nn~m; C
acid, vinylbenzoic acid, sorbic acid, caffeic acid, maleic acid, methylmaleic acid, crotonic acid, isocrotonic acid, fumaric acid, dimethylfumaric acid, methylfumaric acid, dihydroxymaleic acid, allylacetic acid and their salts and esters.
Examples of the monomers of the formula (I) having a carboxyl group and another acidic group and their derivatives, which may be used alone or together with one or more other monomers of the formula (I), include vinylsalicyclic acid carboxy-vinylbenzenesulfonic acid, and their salts and esters.
Examples of the monomers of the formula (I) having a O.Z. 5192 sulfonic or sulfuric acid group and their derivatives, which may be used alone or together with one or more other monomers of the formula (I), include allylsulfuric acid, allylsulfonic acid, methallylsulfuric acid, methallylsulfonic acid, vinylsulfonic acid, 2-hydroxyethylvinylsulfonic acid, vinylbenzenesulfonic acid (i.e. styrenesulfonic acid), vinyltoluenesulfonic acid and their salts and esters.
Examples of the monomers of the formula (I) having a phenolic hydroxyl group and their derivatives, which may be used alone or together with one or more monomers of the formula (I), include vinylphenol (i.e. hydroxystyrene), allylhydroquinone and vinylresorcinol.
In a further embodiment of the process according to the invention, as the monomer (I) use may be made of a mixture of monomers of the general formulae V and VI

cRl~ CHR1' CR1~ CHR5 ~2' (V) and R2l (VI) (HC R3' R4) COOR6 In the formulae (V) and (VI) R1 is hydrogen or a methyl radical, R2 is a divalent organic radical, preferably an aliphatic, cycloaliphatic or aromatic hydrocarbon radical, having up to 10 carbon atoms, or a single bond, R3 is -O- or -NH-, o.z. 5192 R4 is hydrogen or a -SO~3Na~ radical, R5 is hydrogen, a methyl radical or a -R2 -COO~Na~
radical, R6 is hydrogen or Na~ and n' is 4 or 5;
with the proviso that at least one of substituents R4 is a -SO33Na~ radical.
In preferred monomers (V) and (VI) R1 is hydrogen, R2 is a alkylene radical having 1 to 4 carbon atoms, a phenylene radical or a single bond, R3 is -O- or -NH-, R4 is hydrogen or radical -SO~3Na~, R5 is hydrogen or the radical -R2 -COO~ Na3, R6 is hydrogen or Na~ and n~ is 4.
The monomers (V) include modified sugar residues, preferably from pentoses and, in particular, from arabinose.
The sugar residues comprise at least one of the radicals -O-SO~3Na~ (O-sulfate) or -NH-SO~3Na~ (N-sulfate), preferably adjacent to the radical R2 . They have preferably 1 to 4 of these radicals. O-sulfate and N-sulfate radicals can be present simultaneously in one sugar residue, in which case the N-sulfate radical is preferably positioned adjacent to the radical R2 . Alternatively, the sugar residue may comprise exclusively one kind of these radicals, for example the O-sulfate radical. Each of the species of formula (V) specified (residues containing only O-sulfate and residues containing N-O.Z. 5192 sulfate) is suitable, alone or together with other species of formula (V). The mixing proportion is therefore from 0:100 to 100: 0 .
The quantitative proportion in which the monomers of formulae (V) and (VI) are employed can fluctuate within wide limits. Thus the molar ratio of the N-sulfate and/or O-sulfate groups of the monomer of formula (V) to the carboxyl and/or carboxylate groups of the monomer of formula (VI) can be, for example, from 1:100 to 100:1. Preferred molar ratios are between 1:20 and 20:1.
The preparation of the monomers of formula (V) is described in detail for example, in German Patent Publication 197 20 369.8. It will be explained here on the basis of a special case, which starts from D-glucono-1,5-lactone 1 and leads to a monomer of formula (V) which is derived from a pentose, namely d-arabinose. It is within the scope of the skilled worker, however, to transfer the process readily to other suitable precursors.
In a first stage the hydroxyl groups of the lactone 1 are protected by acetalization, for example with acetone in methanol as solvent. In this procedure the lactone is cleaved and an isomer mixture is obtained comprising methyl 3,4;5,6-di-O-isopropylidene-D-gluconate 2 and methyl 2,3j5,6-di-O-isopropylidene-D-gluconate 3. This mixture is reduced in a second stage, for example with lithium aluminum hydride, whereby the carboxylic ester function becomes the carbinol function. An isomer mixture is obtained again, namely of 3,4;
5,6-di-O-isopropylidene-D-sorbitol 4 and 2,3j5,6-di-O-isopropylidene-D-sorbitol 5. In a third ctage, this isomer O.Z. 5192 mixture is oxidized with an oxidizing agent such as sodium periodate and with cleavage of the carbon chain to give a uniform product, the arabinose aldehyde 2,3;4,5-di-O-isopropylidenealdehyde-D-arabinose 6. In the subsequent fourth stage a vinyl function is introduced, for example by a Grignard reaction with 4-vinylphenylmagnesium chloride. A
partially protected 4-vinylphenylpentanepentanol, 2,3;4,5-di-O-isopropylidene-1-(4-vinylphenyl)-D-gluco(D-manno)pentitol 7, is obtained, which is referred to below in shortened form as arasty.
This sequence of stages 1 to 4 is illustrated by the following reaction scheme:

~H ~ o CH3OH4 H~ ~ OH

'- -' ~ - OH

OH _ o X - ~ X

- OH - - OH

_ o ~ _ OHN~04 o ~ ~ 4 - ~oX - oX- oX oX

This reaction sequence has been described in more detail by H. Regeling et al., Recl. Trav. Chim. Pays-Bas 1987 (106), 461: D.Y. Jackson, Synth. Commun. 1988 (18), 337; and G. Wulff et al., Macromol. Chem. Phys. 1996 (197), 1285.

o.Z. 5192 To prepare a compound which corresponds to the arasty 7 and has an amino group in position 1, arasty can be oxidized in a first stage to the corresponding ketone, 2,3;4,5-di-0-isopropylidene-D-arabino 4-vinylphenyl ketone 8.
This is transformed reductively in a second stage to the amine l-amino-l-deoxy-2l3i4/5-di-o-isopropylidene-l-(4-vinylphenyl) D-gluco(D-manno)pentitol 9. This reaction sequence is illustrated by the following formula scheme:

~J

o ~ DMSO/(C0~)2 ~ ~ NaGNBH3 0 _OX _OX _oX

In the first stage, arasty 7 can be oxidized, for example, with a complex of oxalyl chloride and dimethyl sulfoxide at a temperature of ~-50~C in an inert solvent. The reductive amination in the second stage is advantageously achieved using sodium cyanoborohydride as a reducing agent in the presence of ammonium acetate in a solvent under anhydrous conditions at room temperature.
Heparin contains unprotected hydroxyl groups and is O-sulfated and N-sulfated. The compounds 7 and 9 are therefore deprotected (deacetalized) in a first stage and 0-O.Z. 5192 and N-sulfated in a second stage so that the polymer prepared from them is substantially analogous to heparin. Deprotection takes place in an acidic medium, in which ketals are not stable. The protected compounds are heated, for example, with dilute mineral acid or with an acidic ion exchanger to give, from 7, 1-hydroxy-1-deoxy-1-(4-vinylphenyl)-D-gluco(D-manno)pentitol 10 and, from 9, 1-amino-1-deoxy-1-(4-vinylphenyl)-D-gluco(D-manno)pentitol 11. The deprotection and subsequent sulfation are represented by the following formula scheme:

O.Z. 5192 ~CHOH ,~mh~tlit~?* IR 120 CHOH sulfa~ion CHOH

~~ H~ form HO--/ \ --OR' --o \ --OH
--OR' --~X --OH --OR' --~ --OH

R' - H OR SO 3 Na J
CHNH2 CHNH2 CHNHR' 0.1 N HCI HO-- sulfati~n ~ R'O----OH --OR' --OH --OR' --O~
_0~\ --OH --OR' R' = H OR SO~)3 Na(~3 The two compounds 10 and 11 are sulfated, judiciously by means of a sulfur trioxide-pyridine complex.

Because of the deacetalization that has been performed, the sulfation does not lead to a uniform product having one or more sulfate groups in defined positions. However, the primary hydroxyl groups and the amino groups should be sulfated preferentially. By choosing an appropriate molar *Trade-mark O.Z. 5192 ratio of sulfur trioxide to hydroxyl and/or amino groups, the degree of sulfation can be regulated. It is advantageous to introduce on average more than one sulfate group per molecule, since heparin contains about 2.7 sulfate groups per disaccharide unit (corresponding to 1.35 sulfate groups per molecule of monomer). Sulfation of the deprotected amine compound 11 produces, simultaneously, O-sulfate and N-sulfate groups in the molecule, which is desirable in view of the sought-after analogy with heparin.
The sulfation is advantageously conducted at room temperature in order to avoid premature polymerization. After a prolonged period, for example up to 100 hours, the reaction is nevertheless complete. As solvent it is possible, for example, to use excess pyridine or an ether, such as tetrahydrofuran. Since the sulfate groups of the reaction products are unstable to acid, it is advisable to add a water-binding agent, for example a molecular sieve, to the precursor solution before the addition of the sulfur trioxide-pyridine complex. For the same reason it is advisable, after the end of the reaction, first of all to hydrolyze the reaction mixture by adding water followed soon thereafter by a base (which keeps the pH in the alkaline range). One example of a suitable base is a saturated barium hydroxide solution, which at the same time precipitates sulfate ions. Excess barium ions can be precipitated by, for example, introducing carbon dioxide, directly or after careful concentration with removal of solvent. The barium carbonate is filtered off and the filtrate is passed through an ion exchanger column in the Na+
form or is treated otherwise with the ion exchanger in order o.Z. 5192 to exchange the barium ions for sodium ions. From the subsequently concentrated solution it is possible by freeze-drying to recover the products, O-sulfated l-hydroxy-l-deoxy-1-(4-vinylphenyl)D-gluco(D-manno)pentitol 12 and N- and O-sulfated l-amino-l-deoxy-1-(4-vinylphenyl)-D-gluco(D-manno)pentitol 13, in each case in the form of the sodium salt, as pulverulent solids. Both substances correspond to the formula (V) and are suitable monomers for the present invention.
The monomers of formula (VI) are known and readily obtainable substances which contribute the carboxyl or carboxylate groups that are required for the heparin-analogous action. Suitable monomers of formula (VI) have one olefinic double bond and one or two carboxyl and/or carboxylate functions or functions which can be transformed into carboxyl and carboxylate functions, such as carboxylic ester, carboxamide or carboxylic anhydride groups. Sodium ions are preferably used as counter ions to the carboxylate function.
Examples of suitable monomers of formula (VI) are (meth)acrylic, crotonic, 4-vinylbenzoic, maleic, fumaric, itaconic, vinylacetic, ci nn~mi C, isocrotonic, methylmaleic, dimethylfumaric, methylfumaric, dihydroxymaleic and allylacetic acids and their sodium salts.

2. Other monomers which can be used if desired In addition to the monomers of formula (I) to (VI) described, having the stated blood-compatibilizing and antibacterial and/or cell proliferation inhibiting groups, it is also possible at the same time to use other monomers whose O.Z. 5192 activity in this respect is neutral or at most weak. Examples include vinyl ethers, such as vinyl methyl ether and vinyl butyl ether; vinyl ketones, such as vinyl ethyl ketone;
olefins and diolefins such as 1-butene, 1-hexene, 1,3-butadiene, isoprene and chloroprene; acrylamide and methacrylamide; vinylaromatic compounds, such as styrene, vinyltoluene and divinylbenzene; and vinylsiloxanes. These monomers can even be present in a predominant amount, for example accounting for up to 90 mol~, preferably 30 mol~ or less.

3. The aubstrate materials Particularly suitable substrate materials are all polymeric plastics, such as polyurethanes, polyamides, polyesters and polyethers, polyether-block-amides, poly-styrene, polyvinyl chloride, polycarbonates, polyorgano-siloxanes, polyolefins, polysulfones, polyisoprene, polychloroprene, polytetrafluoroethylene (PTFE), poly-acrylates, polymethacryla'tes, corresponding copolymers and blends and also natural and synthetic rubbers, with or without radiation-sensitive groups. The process according to the invention can also be applied to surfaces of painted or otherwise polymer-coated metal, glass or wooden structures.

4. The activation of the substrate surfaces The surface of the substrates can, in accordance with the invention, be activated by a variety of methods.
They are judiciously freed beforehand in a known manner, by means of a solvent, from oils, fats or other cont~m'n~nts.

O.Z. 5192 CA 02226l33 l998-0l-02 4.1 The activation of standard polymers without W -sensitive groups can advantageously be effected by W
radiation, for example in the wavelength range from 100 to 400 nm, preferably from 125 to 310 nm. A suitable source of radiation is, for example, a HERAEUS* Noblelight W excimer device from Hanau, Germany. Mercury vapor lamps, however, are also suitable for substrate activation provided they emit considerable components of radiation within the stated ranges.
The exposure time is in general from 0.1 second to 20 minutes, preferably from 1 second to 10 minutes. It has been found that the presence of oxygen is advantageous. The preferred oxygen pressures are between 2X10-5 and 2x10-2 bar. The operation is conducted, for example, in a vacuum of from 10-4 to lo-l bar or using an inert gas, such as helium, nitrogen or argon, with an oxygen content of from 0. 02 to 20 parts per thousand.

4.2 Activation can also be achieved in accordance with the invention by means of a high-frequency plasma or microwave plasma (for example, Hexagon, Technics Plasma, 85551 Kirchheim, Germany) in air or a nitrogen or an argon atmosphere. The exposure times are in general from 30 seconds to 30 minutes, preferably from 2 to 10 minutes. The energy employed in the case of laboratory devices is between 100 and 500 W, preferably between 200 and 300 W.

4.3 It is also possible to use corona discharge devices (for example, SOFTAL, Hamburg, Germany) for activation. The *Trade-mark O.Z. 5192 exposure times in this case are in general from 1 second to 10 minutes, preferably from 1 to 60 seconds.

4.4 Activation by electron beams or gamma rays (for example from a cobalt 60 source) enables short exposure times which are in general from 0.1 to 60 seconds.

4.5 Flame treatments of surfaces lead likewise to their activation. Suitable devices, especially those having a barrier flame front, can be constructed in a simple manner or obtained, for example, from ARCOTEC, 71297 Monsheim, Germany.
They can be operated with hydrocarbons or hydrogen as combustion gas. In every case, harmful heating of the substrate must be avoided, which is easily achieved by means of intimate contact with a cooled metal surface on the substrate surface facing away from the side subject to flame treatment. Activation by flame treatment is restricted, accordingly, to relatively thin, flat substrates. The exposure times amount in general to from 0.1 second to 1 minute, preferably from 0.5 to 2 seconds, the flames involved being - without exception - nonluminous and the distances of the substrate surfaces from the external flame front being from 0.2 to 5 cm, preferably from 0.5 to 2 cm.

4.6 Furthermore, the substrate surfaces can also be activated by treatment with strong acids or strong bases.
Suitable strong acids which may be mentioned are sulfuric acid, nitric acid and hydrochloric acid. Polyamides, for example, can be treated at room temperature with concentrated O.Z. 5192 sulfuric acid for from 5 seconds to 1 minute. Particularly suitable strong bases are alkali metal hydroxides in water or an organic solvent. Thus, for example, dilute sodium hydroxide solution can be allowed to act on the substrates at from 20 to 80~C for from 1 to 60 minutes. Alternatively, for example, polyamides can be activated by allowing 2~ strength KOH in tetrahydrofuran to act on the surface for from 1 minute to 30 minutes.

4.7 Finally, monomers having W-sensitive groups can be incorporated by polymerization during the actual preparation of the substrate polymers. Examples of suitable such monomers are furyl or c;nn~moyl derivatives, which can be employed, for example, in amounts of from 3 to 10 mol~. Highly suitable monomers of this kind are c-nn~moylethyl acrylate and methacrylate.
In some cases, for example with highly hydrophobic polymers, it may be advisable to activate the substrate surfaces by a combination of two or more of the methods stated. Preferred activation methods are those specified under 4.1 and 4.2.

5. Coatinq bY qraft (co)polymerization If a substrate has been pretreated by one of the methods described above, the activated surfaces are judiciously exposed for from 1 to 20 minutes, preferably from 1 to 5 minutes, to the action of oxygen, for example in the form of air.
Subsequently, the surfaces that have been activated O.Z. 5192 CA 02226l33 l998-0l-02 (including those which have been activated in accordance with 4.7) are coated by known methods, such as dipping, spraying or spreading, with solutions of the vinyl monomer(s) of the formula (I) to be used in accordance with the invention.
Solvents which have been found preferably are water and water-ethanol mixtures, although other solvents can also be used provided they have sufficient solvency for the monomers and provide good wetting of the substrate surfaces. Depending on the solubility of the monomers and on the desired film thickness of the finished coating, the concentrations of the monomers in the solution may be from 0.1 to 50 percent by weight. Solutions with monomer contents of from 3 to 10 percent by weight, for example with about 5 percent by weight, have been found particular preferred in practice and give rise in general and in one pass to coherent coatings which cover the substrate surface and have film thicknesses which can be more than O.l~m.
Following the evaporation of the solvent or even during the evaporation, the polymerization or copolymerization of the monomers applied to the activated surfaces is brought about, by radiation preferably in the shortwave segment of the visible light region or in the longwave segment of the W
region of the electromagnetic radiation. Highly preferable radiation, for example, is that of a W excimer of the wavelengths 250 to 500 nm, preferably from 290 to 320 nm.
Here again, mercury vapor lamps are preferred provided they emit considerable fractions of radiation within the stated ranges. The exposure times are in general from 10 seconds to 30 minutes, preferably from 2 to 15 minutes.

O.Z. 5192 In some cases it is desired to repeat the described operations, including the activation, by means of such a multicoat technique to ensure a hermetically sealed and/or relatively thick coating. Alternatively, it is also possible to immerse the activated substrate, if desired after the oxygen treatment described, into the solution of the vinyl monomer(s) of the formula (I) to be used in accordance with the invention and to irradiate it in the immersed state. By means of guideline experiments it is not difficult to ascertain the irradiation times with a given radiation source and the substrate/solution contact times, which may be relatively long, required to achieve the desired film thickness.
The process according to the invention for the antibacterial and cell proliferation inhibiting coating of the surface of substrates and, in particular, of polymeric plastics permits the establishment of precise molar ratios of different functional groups which are optimum for inhibiting bacterial adhesion and/or propagation and cell proliferation.
Furthermore, the process offers the advantage that, if appropriate activation methods are chosen, plastics which have already become established can, while retaining their mechanical properties and their form, be additionally modified to make them antibacterial and cell proliferation inhibiting.
In general, no other treatments before or after are necessary.
Highly hydrophobic plastics may require a hydrophilicizing pretreatment, for example by chemical etching with acids or bases or by plasma treatment, in order to attain sufficient wettability by the monomer solution. The highly hydrophobic o.z. 5192 CA 02226l33 l998-0l-02 plastics are then hydrophilicized at the same time and activated in the sense of the present invention.
The examples which follow are given to illustrate further the present invention. The monomers used therein are representative of a large number of other compounds which come under the general formulae (I) to (IV).

Examples Monomers 5% strength by weight aqueous solutions of each of the monomers listed in Table 1 were prepared under sterile conditions.

Table 1 - Monomers employed - 5% by weight solution Solution Mo~o~r Abbreviation number S 1 Sodium styrenesulfonate NaSS
S 2 Acrylic acid AAc S 3 Methacrylic acid MAAc S 4 Maleic acid MAc S 5 2-[(N-dimethylamino)ethyl] acrylate DMAEA
S 6 Sodium vinylsulfonate VS
S 7 Methacryloyloxyethylphosphorylcholine, PCHEMA
CH2=C(CH3)-COO-CH2CH2OPO2 -CH2-CH2 N (CH3)3 S 8 Diethylene glycol methacrylate DEGMA
S 9 1,3-Butadiene-1,4-diol diphosphate BDDl,4DP
S 10 Caffeic acid KafAc S 11~ 4-Vinylresorcinol 4VR
S 12 4-Vinylsalicylic acid 4VSAC

* 1% by weight solution o.z. 5192 CA 02226l33 l998-0l-02 Substrates The investigations on the effects of the coatings according to the invention on antibacterial behaviour were conducted on sheets of the plastics listed in Table 2, each of which has a thickness of 0.1 mm and a surface area, relevant for the determination of 4 cm2. They were prepared both by dissolving the powders in solvents, then pouring the solutions into Petri dishes and drying them, and by calendering, extrusion, compression molding or knife coating. In some cases, films from the manufacturer were available.

Table 2 - Films employed Film No. Plastic Name, source Preparation F 1 Polyamide 12 VESTAMID~, HULS AG Extrusion - F 2 Polystyrene VESTYRON~, HULS AG Compression F 3 Polyurethane PELLETHANE~ 2363-A Extrusion DOW CHEMICAL COMPANY
F 4 Polyether-block- VESTAMID~, HULS AG Extrusion amide F 5 Polyethylene VESTOLEN~ A, Extrusion VESTOLEN GmbH
F 6 Polypropylene VESTOLEN~ P, Extrusion VESTOLEN GmbH
F 7 Polyorgano- NG 37-52, Silicon GmbH, Knife coating siloxane Nunchritz F 8 Polyvinyl VESTOLIT~ + DEH Brabendering chloride VESTOLIT Gm~H
F 9 PTFE HOSTAFLON~, Extrusion HOECHST AG

Activation of the substrate surfaces The films were first of all activated, alternatively according to the conditions and techniques stated in Table 3.

o.Z. 5192 CA 02226l33 l998-0l-02 Table 3 - Activation conditions Activation Activating technique Conditions reference A 1 W excimer rays 1 s - 20 min, 1 mbar (= 172 nm) 4 cm distance A 2 Microwave plasma (argon) 1 s - 30 min, 1 mbar A 3 High-frequency plasma 1 s - 30 min, 6 mbar (argon) A 4 Corona 0.1s - 60s, 2 mm distance A 5 Flame treatment CH4:air = 1:10:4 cm distance A 6 ~-rays 1 Mrad A 7 Electron beams 1 min A 8 NaOH solution 1~, 5 min, 60~C
A 9 W excimer rays 10 s - 20 min (= 308 nm) Coatinq of the Substrate Surfaces by Graft (co)Polymerization Following activation, the films, casting or other substrates and also, in the case of industrial manufacture, the extrudates or injection moldings, are coated with the solutions S1 to S16, by the techniques indicated in Table 4.

Table 4 - Coating techniques Coating reference Coating technique T 1 Dipping T 2 Spraying T 3 Spreading - During dipping or after dipping, spraying or spreading, irradiation is carried out with rays in the range 250 - 500 nm, preferably 290 - 320 nm.

O.Z. 5192 Determination of Antibacterial Pro~erties The test for adhesion of bacteria can be performed with various strains. Particularly suitable for this purpose are the bacteria listed in Table 5, since they occur frequently in clinical isolates from infected catheters.

Table 5 - Strains of bacteria for measuring the primary adhesion Strain B 1 Staphylococcus aureus B 2 Staphylococcus epidermidis B 3 Escherichia coli B 4 Klebsiella pneumoniae The method of determining the primary adhesion (i.e.
independently of subsequent multiplication) of these bacterial strains is described below by way of example for Klebsiella pneumoniae. The primary adhesion of the other strains (B1 to B3) was determined in a similar way.

Determ;n~tion of PrimarY Bacteria Adhesion Under Static Conditions An overnight culture of the bacterial strain Klebsiella pneumoniae in yeast extract-peptone-glucose nutrient medium (1% + 1% + 1%) is centrifuged and the extract is taken up again in phosphate-buffered saline (=PBS; 0.05 M
KH2PO4, pH 7.2 + 0.9% NaCl). The suspension is diluted with PBS buffer to a cell concentration of 108 cells/ml. The suspended bacteria are brought into contact for 3 h with the section of film that is to be investigated. This is done by O.Z. 5192 spiking circular film sections having a diameter of 1.6 cm (=4.02 cm2), coated on both sides, onto a preparation needle and shaking them with the cell suspension. Films coated on one side, in the form of a circular, planar disk with a diameter of 4.5 cm and with a supporting membrane of 2-3 cm thick flexible PVC, are clamped into a membrane filter apparatus. The cell suspension is applied to the upward facing side, bearing the test coating, and is shaken for 3 h.
The membrane filter apparatus must be tightly sealed; in other words, no cell suspension may flow out through leak sites.
After the contact time has expired the bacterial suspension is drawn off under suction using a water jet pump and the film sections are washed for 2 minutes by shaking them in a 100 ml glass beaker with 20 ml of sterile PBS solution.
The film section is immersed again in sterile PBS solution and then extracted in a boiling water bath for 2 minutes with 10 ml of heated TRIS/EDTA (0.lM trishydroxyethylaminomethane, 4 mM ethylenediaminetetra-acetic acid, adjusted to pH 7.8 with HCl).
The extraction solution is used to fill small Eppendorf cups and is immediately frozen at -20~C until the extracted adenosine-triphosphate (ATP) is determined by bioluminescence. The determination is carried out as follows:
100 ~l of reagent mix (bioluminescence test CLS II, BOEHRINGER MANNHEIM GmbH) are placed in a transparent polycarbonate tube, and the light pulses are integrated over a period of 10 seconds in a light impulse meter LUMAT* LB 9501 (Laboratorien Prof. Berthold GmbH, 75323 Bad Wildbad, *Trade-mark o.z. 5192 Germany). Then a 100 ~l sample is added and measurement is repeated. The relative light units (RLU) are obtained by subtracting the light pulses in the reagent mix from the number of light pulses measured in the complete batch. This value is related to the number of bacteria which have adhered to the film. The conversion factor between the RLU value and the bacterial count is determined by extracting an aliquot of 0.1 ml of the bacterial suspension containing 108 cells/ml in 10 ml of hot TRIS/EDTA and then determining the ATP content.
For Klebsiella ~neumoniae the value found is 1.74 104 RLU = 1 107 cells in the ATP extract. With a measured value of 4.7 104 RLU from 4 cm2 of film, this gave a value for the primary adhesion per cm2 of film surface of 4.7 104 = 1.175 104 RLU/cm2 - 6.8 106 cells/cm2 Resul tg Compiled in Tables 6a and 6b below are the various conditions and the results of a total of 27 experiments and comparison experiments without prior activation (14, 16, 18, 20, 22, 24, 26).

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O.Z. 5192 Tables 6a and 6b show that the coatings obtained by the process according to the invention lead to a considerable reduction in bacterial adhesion. The reductions are markedly over 50~ in comparison with the uncoated substrates.
Furthermore, the comparison examples (experiments 3, 4 and 15) reveal that, by activating the substrate surfaces with W
excimer rays of wavelength 172 nm (Al) or plasma treatment (A2, A3), higher inhibitions of bacterial adhesion (290~) are - surprisingly - achieved than with other activating means, such as electron beams (A7, experiment 13) or NaOH solutions (A8, experiment 17).
The results reproduced in the tables also show that it is possible to operate successfully with a single monomer (S 7, experiment 25) but that copolymers of two monomers, namely of sodium styrenesulfonate and acrylic acid (S 1 + S 2:
experiment 15), sodium styrenesulfonate and maleic acid (S 1 +
S 4: experiment 17), sodium vinylsulfonate and caffeic acid (S

6 + S 10: experiment 21) and acrylic acid and sodium vinylsulfonate (S 2 + S 6: experiment 27) also give coatings having good antibacterial properties.

O.Z. 5192

Claims (30)

1. A process for making a surface of a substrate antibacterial, compatible with a body fluid or tissue and cell proliferation-inhibiting or -promoting, which process comprises:
subjecting at least one monomer of the general formula:
R-(A) a (I) (wherein:
R is a mono- or diolefinically unsaturated organic radical having the valency a;
a is an integer of from 1 to 6; and A which may be the same or different when a is 2 to 6, is a carboxyl group - COOH, a sulfuric acid group -OSO2OH, a sulfonic acid group -SO3H, a phosphoric acid group -OPO(OH)2, a phosphonic acid group -PO(OH)2, a phosphorous acid group -OP(OH)2, a phenolic hydroxyl group, or a salt or ester of one of these groups) to a graft polymerization under radiative induction onto an activated surface of the substrate, with the proviso that (i) when A is a carboxyl group or a salt or ester thereof, the monomer contains at least one further radical A defined above other than a carboxyl group or a salt or ester thereof or (ii) when A is only a carboxyl group or a salt or ester thereof in a monomer, the monomer is used together with at least one further monomer of the formula (I) in which A is as defined above other than a carboxyl group or a salt or ester thereof, thereby forming a grafted polymer layer on the activated surface.

2. The process as claimed in claim 1, wherein the graft polymerized monomer of the general formula (I) is:
(a) at least one monomer of the formula (I) having, as A, a group as defined in claim 1 other than a carboxyl group or a salt or ester thereof, the monomer being selected from the group consisting of vinylsalicylic acid, carboxy-vinylbenzenesulfonic acid, allylsulfuric acid, allylsulfonic acid, methallylsulfuric acid, methallylsulfonic acid, vinylsulfonic acid, 2-hydroxyethylvinylsulfonic acid, styrenesulfonic acid, vinylbenzenesulfonic acid, vinyltoluenesulfonic acid, vinylphenol, allylhydroquinone, vinylresorcinol, 2-butene-1,4-diol diphosphate, 2-butane-1,4-diol diphosphonate, diallyl phosphite, (meth)acryloyloxyethyl-phosphorylcholine and alkali metal salts thereof, or (b) a mixture of the monomer (a) defined above and at least one other monomer of the formula (I) having, as A, a carboxyl group or a salt or ester thereof, the other monomer being selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, vinylacetic acid, cinnamic acid, vinylbenzoic acid, sorbic acid, caffeic acid, maleic acid, methylmaleic acid, crotonic acid, isocrotonic acid, fumaric acid, dimethylfumaric acid, methylfumaric acid, dihydroxymaleic acid, allylacetic acid and their alkali metal salts and their esters with aliphatic, cycloaliphatic or araliphatic alcohols having 1 to 12 carbon atoms or with groups of the formula:

-(CH2-CH2-O)d-H, -(CH2-CH(CH3)-O)d-H, -(CH2-CH2-cH2-O)d-H or -(CH2)d-NH2-e(R2)e (in which R2 is -CH3 or -C2H5, d is 1, 2, 3 or 4 and e is 0, 1 or 2).

3. The process as claimed in claim 2, wherein the monomer graft polymerized is the monomer (a) alone.

4. The process as claimed in claim 2, wherein the monomer graft polymerized is the mixture (b).

5. The process as claimed in claim 4, wherein the mixture (b) contains a monomer having a sulfonic acid group or a salt thereof and being selected from the group consisting of carboxy-vinylbenzene sulfonic acid, allylsulfonic acid, methallylsulfonic acid, vinylsulfonic acid, 2-hydroxyethyl-vinylsulfonic acid, vinylbenzenesulfonic acid, vinyltoluenesulfonic acid and alkali metal salts thereof.

6. The process as claimed in claim 5, wherein the mixture contains an alkali metal salt of the monomer having a sulfonic acid group.

7. The process as claimed in claim 5 or 6, wherein the monomer having a sulfonic acid group is vinylsulfonic acid or vinylbenzenesulfonic acid.

8. The process as claimed in any one of claims 4-7, wherein the monomer having a carboxyl group or a salt or ester thereof is acrylic acid, methacrylic acid, maleic acid, 2-(N-dimethylamino)ethylacrylate, diethylene glycol methacrylate, caffeic acid or 4-vinylsalicylic acid.

9. The process as claimed in any one of claims 4-7, wherein the monomer having a carboxyl group or a salt thereof is acrylic acid, methacrylic acid, maleic acid or caffeic acid.

10. The process as claimed in claim 1, wherein the monomer of the formula (I) is a mixture of monomers of the general formulae (II) and (III):

(CnH2n-q-x)(COOR1)x (II), and (CnH2n-q-x)(SO3R1)x, (III) (in which:
n independently at each occurrence is an integer from 2 up to and including 6;
x independently at each occurrence is 1 or 2;
q independently at each occurrence is 0 or 2 and R1 independently at each occurrence is -H, an equivalent of a metal ion or a radical of an aliphatic, cycloaliphatic or araliphatic alcohol).

11. The process as claimed in claim 1, wherein the monomer of the formula (I) is a benzene-derived monomer of the general formula (IV):
(C6H6-b-c-d)BbR3c(OH)d, (IV) (in which:

B independently at each occurrence is a straight-chain or branched radical of the formula:
(CnH2n-1-q-x)(COOR1)x or (CnH2n-1-q-x)(SO3R1)x, where R1, n, q and x are as defined in claim 10;
R3 independently at each occurrence is C1-4 alkyl, -NH2, -COOH, -SO3H, -OSO3H, -OPO(OH)2, -PO(OH)2, -OP(OH)2, -OPO(O-)OCH2-CH2-N+(CH3)3, -PO(O-)O-CH2-CH2-N+(CH3)3, -OP(O-)OCH2-CH2-N+(CH3)3 or a salt or an ester of -COOH, -SO3H, -OSO3H, -OPO(OH)2, or -OP(OH)2;
b is 1, 2 or 3;
c is 0, 1, 2 or 3; and d is 0, 1, 2 or 3;
with the proviso that b + c + d ~ 6).

12. The process as claim in claim 1, wherein the monomer of the formula (I) is a mixture of monomers of the general formulae (V) and (VI):

and (in which:
R1' is hydrogen or a methyl radical;
R2' is a divalent organic radical or a single bond;
R3' is -O- or -NH-;

R4 is hydrogen or -SO~3Na~;
R5 is hydrogen, a methyl radical or -R2-COOR6;
R6 is hydrogen or Na; and n is 4 or 5;
with the proviso that at least one of the substituents R4 is -SO~3Na~) .

13. The process as claimed in any one of claims 4 to 9 or claim 10, wherein the monomers are chosen such that the grafted polymer layer comprises (iii) carboxyl and sulfonic acid groups, (iv) carboxyl and sulfonate groups, (v) carboxylate and sulfonate groups, (vi) carboxyl, carboxylate and sulfonate groups, or (vii) carboxyl, sulfonic acid and sulfonate groups.

14. The process as claimed in claim 13, wherein the molar ratio of carboxyl and/or carboxylate groups to sulfonic acid and/or sulfonate groups is from 0. 2 to 3.

15. The process as claimed in claim 13, wherein the molar ratio of carboxyl and/or carboxylate groups to sulfonic acid and/or sulfonate groups is from 0. 4 to 3.

16. The process as claimed in claim 13, wherein the molar ratio of carboxyl and/or carboxylate groups to sulfonic acid and/or sulfonate groups is from 0.4 to 2.

17. The process as claimed in claim 13, wherein the molar ratio of carboxyl and/or carboxylate groups to sulfonic acid and/or sulfonate groups is from 2 to 10.

18. The process as claimed in claim 13, wherein the molar ratio of carboxyl and/or carboxylate groups to sulfonic acid and/or sulfonate groups is from 3 to 10.

19. The process as claimed in claim 13, wherein the molar ratio of carboxyl and/or carboxylate groups to sulfonic acid and/or sulfonate groups is from 3 to 5.

20. The process as claimed in claim 1 or 2, wherein the monomer or monomers of the formula (I) are chosen such that the grafted polymer layer comprises a phosphoric acid group, a phosphonic acid group or a salt or ester thereof.

21. The process as claimed in any one of claims 1 to 20, wherein the activated substrate surface is formed (i) by incorporating a monomer having a UV-sensitive group by polymerization into the substrate or (ii) by UV radiation, plasma treatment, corona treatment, electron beam treatment, flame treatment or treatment with a strong acid or strong base of the substrate surface.

22. The process as claimed in any one of claims 1 to 20, wherein the activated substrate surface is formed by UV
radiation in the wavelength range from 100 to 400 nm with an exposure time of from 0.1 second to 20 minutes to the substrate surface.

23. The process as claimed in any one of claims 1 to 20, wherein the activated substrate surface is formed by UV
radiation in the wavelength range from 125 to 310 nm with an exposure time of from 1 second to 10 minutes to the substrate surface.

24. The process as claimed in any one of claims 1 to 20, wherein the activated substrate surface is formed by radiation of high-frequency plasma or microwave plasma with an exposure time of from 30 seconds to 30 minutes to the substrate surface.

25. The process as claimed in any one of claims 1 to 22, wherein the activated surface is subjected for from 1 to 20 minutes to the action of oxygen, prior to the coating.

26. The process as claimed in claim 25, wherein the oxygen is allowed to act for from 1 to 5 minutes.

27. The process as claimed in any one of claims 1 to 26, wherein the polymerization of the monomer is brought about by radiation of light having a wavelength in the range from 250 to 500 nm.

28. The process as claimed in claim 27, wherein the polymerization of the monomer is brought about by UV radiation in the range from 290 to 320 nm.

29. The process as claimed in any one of claims 1 to 28, wherein the substrate is a medical or biotechnical article, a storage container or a packaging.

30. The process as claimed in claim 29, wherein the article is a catheter, a hose or a pipeline.