Stock material or miscellaneous articles – Composite – Of carbohydrate
Reexamination Certificate
2000-06-30
2002-10-22
Barr, Michael (Department: 1762)
Stock material or miscellaneous articles
Composite
Of carbohydrate
C427S002240, C427S337000, C427S338000, C427S399000, C623S006620
Reexamination Certificate
active
06468667
ABSTRACT:
BACKGROUND OF THE INVENTION
Biological systems usually expose a number of particular carbohydrates on those of their surfaces which are in contact with biological fluids, cells and tissues. Biocompatibility, bioadhesion, cell accumulation, molecular recognition, cell attachment, water retention, lubrication or defense against microbial attack are among the important functions which are thus controlled by the pattern of surface carbohydrates.
Synthetic bulk materials used for the manufacture of ophthalmic moldings in general lack the sufficient biocompatibility and affinity to maintain growth and permanent anchoring of healthy epithelial cells on their surface. A variety of different types of surface modifications has been proposed in the prior art to overcome this problem. However, the known surface coatings often do not provide the desired coating characteristics, for example cell growth ability or the ability to hold a continuous layer of an aqueous solution, e.g. human body fluids such as tears or mucus layers, for a prolonged period of time.
SUMMARY OF THE INVENTION
Surprisingly, it now has been found that the drawbacks of known bulk materials used for the manufacture of ophthalmic moldings may be overcome by covalently linking to the material surface specific carbohydrates which mimic a biological surface appropriate for cell attachment and, especially in case of contact lenses, provide high wettability, lubricity, water retention, on-eye comfort as well as longterm deposit resistance, microbial resistance and favorable lens movement on the eye.
The present invention therefore in one aspect relates to an ophthalmic molding comprising an organic bulk material having covalently bonded to its surface an acceptor saccharide to which is enzymatically attached one or more further carbohydrates selected from the group consisting of galactose, mannose, fucose, galactosamine, N-acetyl galactosamine, N-acetyl glucosamine, ialic acid and an oligosaccharide comprising one or more of the afore-mentioned arbohydrates.
Examples of suitable organic bulk materials are natural or synthetic organic polymers, for example polyaddition and polycondensation polymers (polyurethanes, epoxy resins, polyethers, polyesters, polyamides and polyimides); vinyl polymers (polyacrylates, polymethacrylates, polystyrene, polyethylene and halogenated derivatives thereof, polyvinyl acetate and polyacrylonitrile); elastomers (silicones, polybutadiene and polyisoprene); or modified or unmodified biopolymers (collagen, cellulose, chitosan and the like).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A preferred group of organic bulk materials are those being conventionally used for the manufacture of ophthalmic devices which are not hydrophilic per se. Such materials are known to the skilled artisan and may comprise for example polysiloxanes, perfluoroalkylpolyethers, fluorinated poly(meth)acrylates or equivalent fluorinated polymers derived e.g. from other polymerizable carboxylic acids, polyalkyl(meth)acrylates or equivalent alkylester polymers derived from other polymerizable carboxylic acids, or fluorinated polyolefines, such as fluorinated ethylene propylene, or tetrafluoroethylene, preferably in combination with specific dioxols, such as perfluoro-2,2-dimethyl-1,3-dioxol. Examples of suitable bulk materials are e.g. Lotrafilcon A, Neofocon, Pasifocon, Telefocon, Silafocon, Fluorsilfocon, Paflufocon, Silafocon, Elastofilcon, Fluorofocon or Teflon AF materials, such as Teflon AF 1600 or Teflon AF 2400 which are copolymers of about 63 to 73 mol % of perfluoro-2,2-dimethyl-1,3-dioxol and about 37 to 27 mol % of tetrafluoroethylene, or of about 80 to 90 mol % of perfluoro-2,2-dimethyl-1,3-dioxol and about 20 to 10 mol % of tetrafluoroethylene.
Another preferred group of organic bulk materials are those being conventionally used for the manufacture of ophthalmic devices which are derived from one or more different ethylenically unsaturated monomers comprising a hydrophilic group, for example a carboxy, carbamoyl, sulfate, sulfonate, phosphate, amine, ammonium, acetate or hydroxy group. The hydrophilic groups are inherently present in the bulk material and therefore also at the surface of a ophthalmic device manufactured therefrom. Such materials are known to the skilled artisan and comprise for example polyhydroxyethyl acrylate, polyhydroxyethyl methacrylate (HEMA), polyvinyl pyrrolidone (PVP), polyacrylic acid, polymethacrylic acid, polyacrylamide, polydimethylacrylamide (DMA), polyvinyl alcohol or copolymers for example from two or more monomers from the group hydroxyethyl acrylate, hydroxyethyl methacrylate, N-vinyl pyrrolidone, acrylic acid, methacrylic acid, acrylamide, dimethyl acrylamide, vinyl alcohol and the like. Typical examples are e.g. Polymacon, Tefilcon, Methafilcon, Deltafilcon, Bufilcon, Phemfilcon, Ocufilcon, Focofilcon, Etafilcon, Hefilcon, Vifilcon, Tetrafilcon, Perfilcon, Droxifilcon, Dimefilcon, Isofilcon, Mafilcon, Nelfilcon or Atlafilcon.
Still another group of preferred organic bulk materials are amphiphilic segmented copolymers comprising at least one hydrophobic segment, for example a polydimethylsiloxane or perfluoroalkylpolyether segment, and at least one hydrophilic segment, for example a polyoxyalkylene, poly(vinylpyrrolidone), polyhydroxyalkylacrylate or -methacrylate, polyacyl alkylene imine, polyacryl amide, polyvinyl alcohol, polyvinyl ether or polyol segment, which are linked through a direct bond or a bridge member. Examples are silicone hydrogels, for example those disclosed in PCT applications WO 96/31792 and WO 97/49740 which are herewith incorporated by reference.
Suitable acceptor saccharides comprise mono- or oligosaccharides or suitable derivatives thereof. Throughout this application the term oligosaccharide is to be understood as meaning a carbohydrate having, for example, from 2 to 20 and preferably from 2 to 10 saccharide units. The oligosaccharide may be a linear or a branched oligosaccharide. A suitable derivative of a mono- or oligosaccharide is, for example, a respective carbohydrate which is substituted by carboxy, sulfo, sulfato, thiol, amino or N—C
1
-C
4
-alkanoylamino such as acetylamino, or a suitable salt thereof, or is a carbohydrate comprising a desoxyhexose.
The acceptor saccharide is preferably a mono-, di- or tri- or tetrasaccharide which in case of an oligosaccharide may be linear or branched. In one embodiment of the invention the acceptor saccharide is a mono- or disaccharide and in particular a disaccharide. Examples of preferred acceptor saccharides are thus mannose, lactose, lactobionic acid, N-acetyl lactosamine, galactose, N-acetyl galactosamine and N-acetyl glucosamine and in particular lactose, lactobionic acid, N-acetyl lactosamine or N-acetylgalactosamine. In a further embodiment of the invention the acceptor saccharide is a tetrasaccharide, in particular a branched tetrasaccharide.
The carbohydrate to be enzymatically attached to the acceptor saccharide may be one of the afore-mentioned monosaccharides or an oligosaccharide comprising at least one of said monosaccharides, for example an oligomannoside. It is preferred to enzymatically attach an afore-mentioned monosaccharide which may have any possible stereochemical configuration and preferably has the stereochemical configuration of its natural occurrence. The attachment of galactosamine or sialic acid includes suitable salts thereof. Preferably sialic acid is enzymatically attached to the acceptor saccharide. A further preferred embodiment of the invention comprises the enzymatical attachment of two or more of the afore-mentioned monosaccharides to the acceptor carbohydrate.
The covalent bonding of the acceptor saccharide to the bulk material surface may occur according to any convenient method that is known in the prior art.
According to one embodiment of the invention the ophthalmic moldings may comprise
(a) a bulk material carrying reactive groups on its surface and
(b) a surface coating obtainable by reacting the reactive groups of the bulk material surface with a functional
Chabrecek Peter
Lohmann Dieter
Streiff Markus
Barr Michael
Gearhart Richard I.
Meece R. Scott
Novartis AG
Tsoy Elena
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