Multilayered materials

The subject of the invention is a composite material for biomedical use which has a significantly improved retention time of the aqueous layer on surfaces. This material is made of materials that have adequate mass properties, but unsatisfactory water layer retention capacity. In particular, the material according to the invention is useful for the production of ophthalmic products, in particular contact lenses.

Materials that retain a thin film of aqueous fluid are desirable in many areas. For example, retention of the aqueous fluid layer is beneficial for slippage of the catheters, and may also reduce protein breakdown on the surface of pacemakers and artificial vascular grafts, and may also prevent bacterial colonization on the surface because the bacteria are unable to attach properly. In another aspect, facilitating the movement of the eyelids over contact lenses is important for the user's feeling of comfort; this sliding movement is facilitated by the presence of a continuous layer of tear fluid on the lenses

177 980 contact, a layer that lubricates the surface separates the tissue / eye. However, clinical studies have shown that currently available contact lenses partially dry out between blinks, thereby increasing friction between the eyelid and the lens. Increased friction causes eye pain and contact lens movement. Since the average blink interval is about 12 seconds, it would be beneficial to produce wettable and biocompatible contact lenses that could constantly hold a layer of tear fluid for more than 12 seconds. Current biomedical materials do not meet this requirement; for example, contact lenses produced from a highly water-swellable pHEMA polymer retain such a layer of tears for approximately 5 seconds.

Thus, materials having wettable and biocompatible surfaces are highly desirable and applicable in many areas. The wettability of materials is strongly dependent on the chemical composition of the surface of the material. In particular, the composition of the surface material affects the ability of the surface to retain a continuous layer of an aqueous solution such as tear fluid. Earlier attempts to solve the problem of wettability in the field of ophthalmology have involved the production of a hydrophilic material. For example, in an attempt to make wettable, soft contact lenses, silicone elastomers with protruding epoxy groups were prepared by cross-linking epoxidized silicone compounds (French Patent FR 2 622 201, JM Frances and G. Wajs). Wettability was given to elastomers by grafting glucuronic acid onto epoxy groups. The disadvantage of introducing hydrophyte groups into polymers by block synthesis is that the optimal balance of optical properties (e.g. transparency and refractive index), mechanical properties (e.g. strength, hardness, gas permeability and flexibility) and the throughput of the resulting material will be worse than traditional materials, and therefore these polymers with hydrophyte groups may not meet the requirements for a given application. The inclusion of hydrophyte monomers does not improve the wettability of the lens based on a fluorine polymer or acrylate.

In attempts to produce hard contact lenses compatible with the cornea and ophthalmic fluid, dextran ester of monovinyl compounds with various acrylates were copolymerized (Japanese Patent JP 63/309914, H. Kitaguni et al.). Dextran / methyl methacrylate copolymers were prepared by graft polymerization and wettable contact lenses were obtained (Y. Onishi et al. Contemp. Top. Polym. Sci. 4.149 (1984)). The production of dextran ester copolymers by block polymerization generally results in a limited range of contact lens wettability improvement. The disadvantage of incorporating hydrophyte compounds into polymers by block synthesis is that the optical properties (e.g. transparency and refractive index), mechanical properties (e.g. strength, hardness, gas permeability and flexibility) and the material's processing capacity cannot be optimized independently of each other.

A method of modifying contact lens surfaces is disclosed in GB 2 163 436 (Halpern). According to the said method, the lenses are coated with a carbohydrate, which is then crosslinked either covalently with polyisocyanate or electrostatically with a divalent cation. As a result of the process, cross-linked skin is obtained, which is not covalently attached to the lens and after delamination, e.g. through the eyelid, it delaminates.

An alternative approach is disclosed in WO 90/04609 (Sepracor). Polymeric substrates, especially polymeric membranes, having reactive groups such as hydroxyl or amino groups at the end of polymer chains, react with the polyfunctional parts of a connecting agent having terminal groups such as epoxy, carbonyl, carboxyl, amino, halogen, hydroxyl, sulfonyl halide, acid halide, isocyanate or their combinations that in turn are linked to a ligand such as hydroxy ethyl cellulose or dextran. Because the molecular weight of the polymer chains in the substrate is high, the density of the chain ends, especially at the surface, will be low, and therefore the density of cross-linked polysaccharide chains will be low.

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The use of dextran and other carbohydrates to modify the surface of polymers has also been reported in WO 83/03977, however, in this case the connecting agent was silane and no article such as contact lenses was disclosed.

Further prior art solutions are directed at modifying the surface of contact lenses (US Patent 5,080,924) or ocular implants (document WO 93/03776), respectively, in which the amino groups on their surface react with dialdehydes and are then coupled with polysaccharides. However, the reaction of the aldehyde with the polysaccharide hydroxyl groups da, acid-labile, ketal bond.

All of the above methods require the presence of an article with chemically reactive groups suitable for the intended covalent reaction. Many materials of interest for ophthalmic applications and implantable biomaterial products do not have adequate reactive groups on the surface, such as silicone-based contact lenses and polytetrafluoroethylene vascular grafts. The composite material according to the invention uses a bulk material, the surface of which can be transformed to become susceptible to covalent maintenance of the coating, which highly retains water layers. Preferably, the surface of the polymeric material is activated by gas plasma surface treatment (glow discharge).

Numerous techniques are known for treating the surface of polymeric materials: corona discharge, flame treatment, acid etching, and many other methods that are intended to chemically modify surfaces. Among the disadvantages of these techniques is the use of them or the formation of harmful chemicals, often excessive processing depth, non-uniform treatment at the microscopic level, and often sharp etching and pitting that lead to a change in surface topography. Etching depth is important because with transparent materials, such as those required for optical lenses, it can affect the transparency and smoothness of surfaces after too rough treatment.

Treatment of polymeric surfaces with gas plasmas provides favorable, very low treatment depth and uniformity on a microscopic scale. Gas plasma (also known as glow discharge) is produced by an electric discharge in a gaseous atmosphere under reduced pressure ("vacuum"). This creates a stable, partially ionized gas that can be used to carry out the reaction on the surface of the substrate, because the gas plasma environment even activates those chemical compounds that are non-reactive under normal conditions. The intensity of treatment at the surface is generally relatively high, while the depth of penetration with plasma treatment is very low, on the order of 5-50 nanometers, with a treatment intensity sufficient for useful surface modification. Surface topography and optical clarity do not change if the plasma exposure process is not carried out for periods of time significantly exceeding the time needed to achieve the desired chemical surface modification. Thus, this process has much less changes in material properties than with alternative treatment technologies.

Gas plasma techniques can give two types of results. In the first, commonly referred to as plasma surface treatment, the surfaces of the treated polymeric material ("substrate") are subjected to plasma formed in one or more inorganic vapors, or in some selected organic vapors. Plasma treatment replaces some of the primary chemical groups on the polymer surface with other new groups that are raised from the gas plasma. For example, plasma surface treatment of polytetrafluoroethylene in ammonia plasma leads to the removal of surface portions of fluorine atoms by breaking the CF bond and introducing amine groups into the modified surface layer by forming a CN bond. Thus, plasma surface treatment in suitable vapors such as ammonia, carbon dioxide or steam can be used to place on the surface of any polymeric material reactive chemical groups, such as an amino, carboxyl or hydroxyl group, suitable for subsequent covalent immobilization different molecules.

The second type of plasma technique is commonly called plasma polymerization and occurs when a discharge hits most organic vapors. In contrast to plasma surface treatment, in which less than a new material monolayer is added, the plasma polymerization technique leads to the formation of a film coating, which can be several micrometers thick and can completely cover the substrate.

Plasma polymers are covalently bound to the underlying substrate. The covalent attachment of the plasma coating to the bulk of the material ensures that the plasma polymer does not separate. In addition, plasma polymers are highly cross-linked and do not have low molecular weight fragments that migrate to body tissue or fluids. By appropriately selecting monomer vapors and plasma conditions, a plasma polymer coating may be formed containing specific, chemically reactive groups that are also suitable for subsequent chemical attachment of various molecules to the surface.

In the composite material of the invention, the surface of the polymeric material, which does not originally contain suitable reactive groups, can be activated by plasma surface treatment, plasma polymerization or plasma polymerization followed by plasma surface treatment.

Composite material, in particular for the production of ophthalmic products, in particular contact lenses, with at least one wettable surface, containing a bulk material, having reactive groups on the surface and a hydrophilic coating attached to the bulk material, the hydrophilic coating consisting of a carbohydrate attached to said reactive groups according to the invention are characterized by that the carbohydrate is covalently attached directly to the reactive groups, which groups are amino groups.

The composite material has reactive groups originally contained in the bulk material or the reactive groups are attached to the surface of the bulk material by plasma treatment of the surface.

The carbohydrate in the composite material is a polysaccharide or non-polysaccharide carbohydrate.

Preferably, the carbohydrate is selected from the group consisting of dextran, chitosan, hyaluronic acid, mucin and phycoidan, and most preferably is dextran.

Preferably, the carbohydrate is glucosamine.

The composite material of the invention contains a carbohydrate that is covalently bonded via a hydrolytically stable bond to the plasma surface prepared on the base material. A plasma surface made on a base or mass basis includes either the surface of the base material treated (or modified) with plasma or the coating with a plasma polymer of the base material. The basic material is selected due to its mass properties, such as mechanical strength, flexibility, gas permeability, optical clarity, to be suitable for the intended use of the composite.

The composite material of the invention is used, in particular, for the production of an ophthalmic article that provides increased comfort to the user, the article consisting of a bulk material and a hydrophyte coating as defined above. The hydrophilic coating consists of a carbohydrate covalently attached to the plasma surface prepared on the bulk material, e.g. as a thin, completely covering the plasma polymer coating.

The composite material according to the invention is used in particular for the production of an ophthalmic article such as a contact lens with one or more wettable surfaces capable of holding a continuous layer of aqueous fluid on it, the composite containing a carbohydrate which is covalently bonded by means of a hydrolytically stable

177 980 binding to reactive groups contained primarily in the bulk of the material and on the surface of the ophthalmic article.

The carbohydrate is attached to the reactive groups directly.

The wettable composite material according to the invention, especially for the production of ophthalmic articles, can be produced by a method which comprises the following steps.

1. subjecting the non-composite biomedical product, in the desired final form, to low pressure plasma in the vapors of at least one organic and / or inorganic compound, under conditions in which a thin film containing reactive groups is deposited on the desired surface or surfaces of the base material,

2. optionally, reacting said reactive groups with activating groups,

3. optionally, treating the carbohydrate with a reagent that modifies said carbohydrate so that it is able to react with the reactive surface or functional groups,

4. reacting reactive groups or functional groups with a carbohydrate,

5. optionally, treating the surface immobilized carbohydrate with a reagent to fix the bond between the carbohydrate and the surface.

The resulting material is preferably washed and properly packaged in a form ready for use.

The wettable composite material according to the invention, especially for the production of ophthalmic products, having primary (a priori) reactive groups contained in the bulk material, can be produced by a process which comprises the following steps.

- optionally, reacting the reactive groups originally contained in the bulk material of the non-composite ophthalmic article in the desired final form, with the activating group,

- optionally treating the carbohydrate with a reagent that modifies said carbohydrate so that it is able to react with the reactive surface or functional groups,

- reacting reactive groups or functional groups with a carbohydrate,

- optionally, treating the carbohydrate immobilized on the surface with a reagent to fix the bond between the carbohydrate and the surface.

The base mass material can be any material traditionally used in the production of biomedical products, e.g. contact lenses, which as such are not hydrophilic. Such materials are known to those skilled in the art and may, for example, include polysiloxanes, fluorinated (meth) acrylates or equivalent fluorinated comonomers, e.g. from other polymerizable carboxylic acids, alkyl (meth) acrylates or equivalent alkyl comonomers derived from other polymerizable carboxylic acids or fluorinated polyolefins, such as fluorinated ethylene propylene or tetrafluoroethylene, preferably in combination with specific dioxols such as perfluoro-2,2- dimethyl-1,3-dioxole. Examples of suitable base mass materials are Neofocon, Pasifocon, Silafocon, Fluorsilfocon, Paflufocon, Silafocon, Elastofilcon, Fluorofocon, or Teflon AF material, such as Teflon AF 1600 or Teflon AF 2400, which are copolymers of about 63-73 mole% perfluoro-2.2 -dimethyl-1,3-dioxol and about 37-27 mole% tetrafluoroethylene, or about 80-90 mole% perfluoro-2,2-dimethyl-1,3-dioxol and about 20-10 mole% tetrafluoroethylene.

The base mass material can also be any material traditionally used in the production of biomedical products, e.g. contact lenses, which are hydrophilic as such, because reactive groups, e.g. amino or hydroxyl groups, are contained primarily in the main mass material, and therefore also on the surface of the produced from it a biomedical product. Such materials are known to those skilled in the art. Typical examples include e.g. Polymacon, Tefilcon, Methafilcon, Deltafilcon, Bufilcon, Phemfilcon, Ocufilcon, Focofilcon, Etafllcon, Hefilcon, Vifilcon, Tetrafilcon, Perfilcon, Droxifilcon, Dimefilcon, Isofilcon, Mafilcon or Atlafilcon. Most of these materials are based on HEMA, but suitable materials may also be based on other monomeric or polymeric substrates

177 980 having reactive groups, e.g. hydroxyl or amino groups, such as e.g. polyvinyl alcohol.

The mass material can be any blood contact material traditionally used to make kidney dialysis membranes, blood storage containers, pacemaker drainage or vascular grafts. Examples of mass material may be polyurethane, polydimethylsiloxane, polytetrafluoroethylene, polyvinyl chloride or Dacron ™.

In addition, the mass material can also be an inorganic or metallic material with suitable reactive groups or without reactive groups, e.g. ceramic material, quartz or metals, such as gold or other polymeric or non-polymeric substrates. Ceramic materials, preferably polysaccharide coated, are very useful in biomedical implantation applications. In addition, it is expected that e.g. for biosensor purposes, dextran-coated substrate materials will reduce non-specific binding effects if the coating structure is well regulated. Biosensors may require polysaccharides on gold, quartz and other non-polymeric substrates.

Reactive groups initially (a priori) present on the surface of the mass material or introduced or attached to the surface of the mass material by plasma surface preparation are amine groups.

Suitable organic or inorganic compounds for the plasma surface preparation step are e.g. ammonia, steam, carbon dioxide, carbon monoxide, noble gases, e.g. argon, oxygen, ozone or air, alcohols, amines or alkanones, preferably lower alkanols having up to eight carbon atoms, lower alkylamines having up to eight carbon atoms or lower alkanones having up to eight carbon atoms, e.g. methanol, ethanol, ammonia, methylamine, ethylamine, heptylamine or acetone or many other compounds known to those skilled in the art of plasma surface preparation. In addition, mixtures of the abovementioned compounds may also be used.

The first stage of judging a thin film coated with a plasma polymer containing on its surfaces reactive groups such as amino or hydroxyl groups is described in the applicant's international patent application PCT / AU89 / 00220 (Griesser et al.) And in HJ Griesser and RC Chatelier in the Journal of Applied Polymer Science Applied Polymer Symposium 46, 361-384 (1990).

Suitable activating compounds for optional step 2 are e.g. anhydrides or activated esters such as 2,2-trifluoroethanesulfonyl chloride, p-toluenesulfonyl chloride, cyano bromide or nitrophenyl esters.

Suitable carbohydrates of the invention include natural products, modified carbohydrates and synthetic carbohydrates. Examples of these carbohydrate groups are sugars such as monosaccharides, di- and oligosaccharides, cyclic oligosaccharides, linear polysaccharides, or homopolysaccharides or heteropolysaccharides, branched polysaccharides, segmented polysaccharides, lipopolysaccharides, glucoproteins and proteoglycans. Modified products or synthetic products can be modified, e.g. by oxidation, etherification or esterification, they may further contain functional groups such as aldehyde groups, acetal groups, ketal groups, acylamino groups, preferably acetylamino groups, anhydride or lactone groups. They may still have groups that may have had a charge, such as -NH₂, -COOH, -OSO3H or -OP (O) (OH)₂.

Examples of suitable carbohydrates are known to those skilled in the art and can be found in traditional textbooks or monographs. The following specification is exemplary only and does not constitute a limitation of the invention.

Suitable sugars are e.g. glucosamine, galactamine, neuraminic acid, muramic acid, sialic acid, L-fructose, arabinose, xylose, glucuronic acid, gluconic acid or levoglucosan.

Suitable oligosaccharides are e.g. lactose, maltose, cellobiose, chitohexanose, trehalose, isomaltulose, leukrose.

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Suitable polysaccharides and derivatives are e.g. hyaluronic acid, deacylated hyaluronic acid, chitosan, chitin 50, fucoidan, carrageenans, dextran, blue dextran, aminated dextran, galactomannan, glucomannan, pullulan, glycosaminoglycan, heparin, pectin, agarose, xanthan, hydroxypropyl cellulose or chitosan, carboxymethyl cellulose or chitosan, emulsion, laminaran, inulin, pustulan, scleroglucan, schizofillan or mucopolysaccharides.

Further examples of suitable carbohydrates are D-ribose, L-arabinose, D-xylose, L-fucose, D-mannose, D-galactose, D-glucosamine, muramic acid, D-galactosamine, D-glucoronic acid, D-mannuronic acid, acid D-galacturonic, L-glycero-D-mannoheptose, neuraminic acid. Further examples of polysaccharides are agarose, alginates, carrageenan, cellulose derivatives such as acetate, carboxymethyl, ethyl, hydroxyethyl, hydroxypropyl, hydroxypropyl methyl, methyl cellulose, chitin / chitosan, dextran, furcellar resin, guellan resin , acacia, heparin, hyaluronic acid, hydroxypropyl guar resin, karaya resin, laminaran, carob resin, pectin (low and high methoxy), ramsan resin, starches, tragacanth, vellan, xanthan.

Examples of particularly suitable monosaccharides include glycerol, threose, glucose, galactose and fructose. Examples of particularly suitable oligosaccharides include sucrose, maltose, lactose and cellobiose. Examples of particularly suitable polysaccharides include dextrans, starches, dextrins, glycogens, inulin, glycosaminoglycans and mucopolysaccharides, further preferred are dextran, chitosan, hyaluronic acid, mucin, fucoidan and glucosamine.

Naturally occurring carbohydrates can be modified to increase their reactivity with activated surfaces. For example, oxidation of dextran with periodate gives aldehydes that can react with amines on the surface of the material; treatment of dextran with bromoacetic acid in an alkaline solution places protruding carboxymethyl groups on the polysaccharide backbone, which in turn can form an ester or amide bond with surface hydroxyl or amino groups, respectively; treatment of dextran with chloroethylamine in an alkaline solution places protruding aminomethyl groups on the polysaccharide skeleton, which in turn can react with surface epoxy groups, acid chloride or tosylate groups.

The second stage can be carried out by immersing the plasma treated material in the solution or vapor of an oligo or bifunctional compound. For example, the surface may be immersed in a solution of 0.1-5.0 ml epichlorohydrin (preferably 0.2-2.0 ml) and 10-100 ml 0.4 ml 0.4 m sodium hydroxide (preferably 20-30 ml ) in 10-100 ml of ethylene glycol dimethyl ether (preferably 20-30 ml) for 1-6 hours (preferably 4-6 hours) at 10-60 ° C (preferably 20-30 ° C). Alternatively, the surface may be immersed in a solution containing 20 ml of water, 0.4 ml of 1,4-butanediol diglycidyl ether and 1 ml of benzyltrimethylammonium hydroxide at 60 ° C for 5 hours. The sample is then rinsed with water at room temperature.

The reaction between the carbohydrate and reactive groups on the surface is carried out in such a way that the outermost surface of the new composite material is provided with a high water retention carbohydrate layer. Preferably, the activated surface material is placed in a carbohydrate solution for a suitable period of time. For example, the method described by S. Lofas and B. Johnsson in J. Chem. Soc .: Chem. Commun. 1526 (1990). Thus, the surface can be reacted with 0.1-15.0 g (preferably 2.0-5.0 g) of dextran (molecular weight 1,000-5,000,000 Da, preferably 500,000-2,000,000 Da) in 10 -50 ml (preferably 20-30 ml) 0.01-5.0 m (preferably 0.1-2.0 m) sodium hydroxide for 0.1-48 hours (preferably 20-25 hours) at 10-60 ° C (preferably 20-30 ° C). Excess dextran is washed away by rinsing the sample with distilled water. Alternatively, the material may be immersed in a solution containing 20 ml of water, 0.2 g of dextran (molecular weight 1,000-40,000,000 Da, preferably 500,000-40,000,000 Da) and 1 ml benzyltrimethoxide hydroxide at 60 ° C. 18 hours. Again, excess dextran is washed off by rinsing the sample with distilled water.

Ophthalmic products for which the composite material according to the invention is used are e.g. contact lenses, an eye dressing or intraocular lens, and preferably contact lenses.

The composite material according to the invention, in particular for the production of ophthalmic articles, in particular contact lenses, with one or more, preferably one or two wettable surfaces, capable of permanently holding on them a layer of aqueous fluid, including base material and hydrophilic coating, is characterized by that the hydrophilic coating consists of a carbohydrate, including a modified carbohydrate, covalently attached to reactive groups on the surface of the mass material directly, in which the said reactive groups are or originally (a priori) contained in the mass material, or in which the said reactive groups have been attached to the surface of the mass material by plasma surface treatment, the reactive groups being groups amine.

Preferably, the reactive groups are primarily contained in the bulk material, the carbohydrate being a polysaccharide, directly attached to the reactive groups. Said carbohydrate is preferably selected from dextran, chitosan, hyaluronic acid, mucin, fucoidan and glucosamine.

Preferably, the reactive groups are initially contained in the bulk material, the carbohydrate being a non-polysaccharide carbohydrate directly attached to the reactive groups.

Preferably, the reactive groups are initially contained in the bulk material, the carbohydrate being dextran directly attached to the reactive groups.

Preferably, the reactive groups have been attached to said surface by plasma surface treatment, wherein the carbohydrate is a polysaccharide directly attached to the reactive groups. Said carbohydrate is preferably selected from dextran, chitosan, hyaluronic acid, mucin, fucoidan and glucosamine, most preferably it is dextran.

Ophthalmic articles made from the composite material according to the invention have various, unexpected advantages over known articles, which makes these articles, and especially contact lenses, very suitable for practical purposes, e.g. as contact lenses for prolonged wear. For example, they have high surface wettability, which wettability can be demonstrated by their contact angles, water retention by them and their time of rupture of the water film or sometimes of tearing of the tear film. The retention time of the water is closely related to the time of breaking the water film ("BUT") and the time of breaking the tear film with the fact that a high water retention time results in a high water film breaking time or a high tear film breaking time.

In addition, ophthalmic products such as contact lenses have a very pronounced biocompatibility combined with good mechanical properties. For example, no harmful effects on the eye have been generally observed, while protein or lipid adsorption is low, and salt formation is also lower than with conventional lenses. In general, it can be said that spoilage is low, bacterial adhesion is low and bioerosion is low, while good mechanical properties can be found, for example, by low friction coefficient and low abrasion properties.

To sum up, off-made articles made from the composite material of the invention, such as contact lenses, provide minor spoilage to the debris of broken cells, cosmetics, dust or dirt, solvent vapors or chemicals, while providing high comfort to the patient wearing such contact lenses due to a soft hydrogel surface which, for example, ensures very good eye contact lens movement.

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Biomedical products (e.g., renal dialysis membranes, blood storage containers, pacemaker cables or vascular grafts) are resistant to protein deterioration due to the continuous layer of bound water, which reduces the rate and extent of clot formation. Blood contact devices are therefore hemocompatible and biocompatible.

Further advantages accompanying the invention are apparent to those skilled in the art from the disclosure and examples. Examples are given only to illustrate the invention and not to limit it.

If the carbohydrate contains trans adjacent diol, then such a carbohydrate (e.g. dextran) may be partially oxidized with a suitable oxidizing agent, e.g. sodium periodate, thereby resulting in ring cleavage and formation of an aldehyde function. Aldehyde functional groups can react with amine groups present as reactive groups or as functional groups on the surface of a biomedical product, forming a group -N = CH-. These groups may be reduced with a suitable reducing agent to the hydrolytically stable group -NH-CH₂- connecting the carbohydrate molecule to the surface of the article.

In the examples, unless otherwise stated, temperatures are given in degrees Celsius and contact angles are given in degrees.

Example 1 (comparative). Commercially available contact lenses made of fluoropolymer (Fluorofocon A *¹⁴) were removed from the brine solution in which they were stored, rinsed with distilled water and put in for in vivo testing (with unconserved buffered brine). Each lens was fitted to a patient not adapted to wearing contact lenses. Patients were selected so that the lenses could be adjusted properly. The following variables were measured: (1) total wettability, (2) front surface break time (FS BUT), (3) surface drying speed, (4) surface coverage. The variables were evaluated immediately after insertion and again 10 minutes after insertion.

Example2 (comparative). Commercially available silicone elastomer contact lenses (Elastofilcon A ™) were removed from the solution in which they were stored and rinsed with distilled water, and then allowed to dry before measuring the air / water contact angles.

Contact angles were measured using a modified Kernco-G2 goniometer to measure the contact angle. By placing the sample on a flat podium and placing a drop of distilled water on the tip of the previous lens surface using a micrometric syringe and then aligning it with rotary crossed hair in the eyepiece, tangentially to the curvature of the lens and the drop on the water / air / lens interface, the angle can be measured contact surface (SCA). The micrometer-driven syringe was then used to gradually increase the volume of the drop by injecting more water into it until the drop began to expand at the surface; at this point the contact angle at expansion was measured using rotation of the hair intersection (ACA). The micrometrically driven syringe was then used to gradually reduce the volume of the droplet by pulling water out of it until the drop started to retract, at which point the retraction contact angle (RCA) was measured.

Example3 (comparative). An important criterion for suitability is the time it takes for water to withdraw from 50% of the surface of a substrate, such as contact lenses. This parameter is abbreviated "WRT" and is given in seconds, in this example and the following. Fluorinated ethylene propylene was used as the bulk material. This material has no WRT time <1 second without modifying its surface.

Example 4. A flat substrate of fluorinated ethylene propylene was plasma treated in the presence of heptylamine. 1 g polysaccharide in 200 ml water was treated with 3 g NaJO₄ and reacted with a plasma-treated surface having amino groups on its surface in the presence of NaCNBH₃ at pH 6 to 9. A substrate with a hydrophilic coating was obtained, for which the time it took for water to withdraw from 50% of the surface (WRT) was measured. The following results were obtained.

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<td></td><td>polysaccharide</td><td>MW (KDa)</td><td>WRT (knot)</td>

<td>and)</td><td>dextran</td><td> 9,3</td><td> 180</td>

<td>b)</td><td>dextran</td><td> 74,2</td><td> 180</td>

<td>c)</td><td>dextran</td><td> 515</td><td> 180</td>

<td>d)</td><td>dextran</td><td> 2000</td><td> 180</td>

<td>e)</td><td>blue dextran</td><td> 2000</td><td> 180</td>

<td>and)</td><td>pectic acid</td><td>not marked</td><td> 180</td>

<td>g)</td><td>polikwat</td><td>not marked</td><td> 90</td>

Example 5. Contact lenses of Elastofilcon were plasma treated in the presence of heptylamine. 74.2 kDa molecular weight (MW) dextran was treated with NaJO₄/ NaCNBn₃ and reacted with plasma treated contact lenses having amino groups on their surface. Lenses with a hydrophilic coating were obtained, for which the time taken for water to retract from 50% of the surface (WRT) of 180 seconds was measured.

Example 6. Contact lenses from Tefilcon were plasma treated in the presence of heptylamine. 74.2 kDa molecular weight dextran (MW) was treated with NaJO4 / NaCN.BH₃ and reacted with plasma treated contact lenses having amino groups on their surface. Contact lenses with a hydrophilic coating were obtained, for which the time required for water to withdraw by 50% from the surface was 90 seconds. In contrast, contact lenses from Tefilcon, without modifying their surface, have a WRT value of 10 seconds.

Example 7. A flat (a) polyurethane, (b) glass and (c) A1-Kapton substrate was plasma treated in the presence of heptylamine. The polysaccharide was treated with NaJO4 / NaCNBH3 and reacted with a plasma-treated substrate having amino groups on its surface. A substrate with a hydrophilic coating was obtained, for which the time it took for water to withdraw from 50% of the surface (WRT) was measured.

The following results were obtained.

<td></td><td>polysaccharide</td><td>MW (KDa)</td><td>WRT (knot)</td>

<td>and)</td><td>dextran</td><td> 74,2</td><td> 900</td>

<td>b)</td><td>dextran</td><td> 74,2</td><td> 120</td>

<td>c)</td><td>dextran</td><td> 74,2</td><td> 120</td>

Example 8. A flat substrate of fluorinated ethylene propylene (FEP) or perfluoropolyether (PFPE) was plasma treated in the presence of a) ammonia, b) ethylenediamine or c) heptylamine. The molecular weight dextran was treated with NaJO4 / NaCNBH3 and reacted with a plasma treated substrate having amino groups on the surface. A substrate with a hydrophilic coating was obtained, for which the time it took for water to withdraw from 50% of the surface (WRT) was measured.

The following results were obtained.

<td></td><td>subsoil</td><td>plasma gas</td><td>WRT (knot)</td>

<td>and)</td><td>FEP</td><td>ammonia</td><td> 160</td>

<td>b)</td><td>FEP</td><td>ethylenediamine</td><td> 160</td>

<td>c)</td><td>PFPE</td><td>heptylamine</td><td> 110</td>

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Example 9. Various contact lenses were plasma treated in the presence of ammonia or heptylamine. Molecular weight dextran was added to NaJO₄/ NaCNBH₃ and reacted with plasma contact lenses treated with amino groups on their surface. Contact lenses with hydrophilic coating were obtained, for which the time required for water to withdraw from 50% of the surface (WRT) was measured.

The following results were obtained.

<td></td><td>contact lens material</td><td>plasma gas</td><td>WRT (knot)</td>

<td>and)</td><td>Tefilcon</td><td>ammonia</td><td> 60</td>

<td>b)</td><td>silicone material *</td><td>ammonia</td><td> 115</td>

<td>c)</td><td>silicone material *</td><td>heptylamine</td><td> 100</td>

<td>d)</td><td>Atlafilcon</td><td>heptylamine</td><td> 130</td>

* The silicone material used here is a copolymer consisting of 15% by weight of methyl methacrylate, 15% by weight of tris (trimethylsilyloxy) silyl-propyl methacrylate and 70% by weight of a macromer having hydroxybutyl units terminated with dimethylsiloxane and isophorone diisocyanate with isocyanate groups with hydroxy terminal groups siloxane, the macromer being terminated with isocyanatoethyl methacrylate, whose isocyanate groups reacted with siloxane terminal hydroxyl groups.

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