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Bifunctional-modified hydrogelsRelated Patent Categories: Synthetic Resins Or Natural Rubbers -- Part Of The Class 520 Series, Natural Rubber Compositions Having Nonreactive Materials (dnrm) Other Than: Carbon, Silicon Dioxide, Glass Titanium Dioxide, Water, Hydrocarbon, Halohydrocarbon, Ethylenically Unsaturated Reactant Admixed With A Preformed Reaction Product Derived From: (a) At Least One Polycarboxylic Acid, Ester, Or Anhydride; (b) At Least One Polyhydroxy Compound; And (c) At Least One Fatty Acid Glycerol Ester, Or A Fatty Acid Or Salt Derived From A Naturally Occurring Glyceride, Tall Oil, Or A Tall Oil Fatty Acid, Containing Chemically Combined Protein Or Biologically Active PolypeptideBifunctional-modified hydrogels description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060100369, Bifunctional-modified hydrogels. Brief Patent Description - Full Patent Description - Patent Application Claims
PRIORITY [0001] Priority is hereby claimed to provisional application Ser. No. 60/285,782, filed 23 Apr. 2001, the entire contents of which is incorporated herein. FIELD OF THE INVENTION [0003] The invention is directed to hydrogels modified using bifunctional reagents, use of the hydrogels to deliver drugs or other biologically-active agents to a mammal in need thereof, compositions containing the hydrogels described herein, and devices, such as wound dressings, diapers, catamenial devices, etc., incorporating the hydrogels. INCORPORATION BY REFERENCE [0004] All of the reference listed in the "References" section are incorporated herein. BACKGROUND [0005] Biological systems, such as healing and embryonic development, operate under spatially- and temporally-controlled orchestration. A myriad of signals and cells all act, in space and time, to heal a cut, for example, or to surround and neutralize a foreign body. The efficacy of current materials used to construct biomedical devices is limited by a lack of multi-functional structures to complement the inherent dynamics of these biological systems. [0006] For example, most wound dressings provide nothing more than a simple barrier to shield the wound and to prevent foreign objects from entering the would. Other newer types of dressings also include antibiotics to prevent sepsis at the wound site. However, these dressings do not address, for example, the exudation which occurs from a wound. Thus, these dressings must be changed often. [0007] Certain biodegradable polymers have been used in burn dressings, hemostatic patches, and the like. These biodegradable polymers provide a barrier and possibly a tissue scaffold for regrowth. However, these types of dressing have no therapeutic effect. While such types of dressings provide effective barriers to physical disturbance of the wound site, scarring is still extensive. [0008] Despite the extensive investigation of novel wound dressing materials, very few materials are in current clinical use. An ideal functional wound dressing should have the following properties: It should be non-toxic, biocompatible, and permeable to moisture and gases to absorb wound exudate and toxins as well to maintain appropriate humidity and oxygen levels. It should be porous to prevent swelling of the wound bed and accumulation of the fluid between the wound site and the material. It should be flexible and durable and minimize local inflammation and infection, thereby promoting new vascularization, re-epithelialization, and normal healing. [0009] Hydrogels are three-dimensional networks capable of absorbing copious amounts of water. Hydrogels have been explored for many uses, including drug delivery devices, wound dressing materials, contact lenses, and cell transplantation matrices. Edible hydrogels, such as gelatin, find extensive use in various food-related applications, such as texture modification, gelling, clarification of beers and wines, and as medicine capsules. SUMMARY OF THE INVENTION [0010] The invention is directed to hydrogels comprising a polymer matrix, preferably gelatin or a synthetic polymer (preferably a biodegradable polymer, although the polymer may also be non-biodegradable), modified to contain bifunctional poly(alkylene glycols) covalently bonded to the polymer matrix. Heterobifunctional, poly-C.sub.1-C.sub.6-poly(alkylene glycol) molecules, preferably poly(ethylene glycol) molecules (hPEGs), each having an .alpha.-terminus and an .omega.-terminus, are bonded to the polymer backbone via covalent bonds involving either of the .alpha.- or .omega.-termini. One or more biofunctional agents (i.e., pharmacologically-active agents) are then bonded to the other of the .alpha.- or .omega.-termini (i.e., the free termini) of the hPEGs, thereby yielding a modified, pharmacologically active, homogenous, and covalently-assembled hydrogel. A schematic representation of the preferred embodiment of the invention is shown in FIG. 4. [0011] Any pharmacologically-active agent, without limitation, can be incorporated into the hydrogel, including (by way of illustration and not limitation) vulnerary agents, hemostatic agents, antibiotics, antithelmintics, anti-fungal agents, hormones, anti-inflammatory agents, proteins, polypeptides, oligonucleotides, cytokines, enzymes, etc. [0012] The hydrogels of the present invention find many uses, the preferred of which is as a functional wound dressing. In this preferred embodiment, the hydrogel contains as a pharmacologically-active agent a vulnerary agent covalently bonded to a biodegradable polymer matrix via a differentially-modified, .alpha.- and .omega.-substituted PEG linker. [0013] The hydrogels of the present invention may also be incorporated into bandages, surgical and dental wound packing material, diapers and catamenial devices, and the like. [0014] The novel hydrogel constructs described herein are not physical blends, which are common in the formulation of current biomedical hydrogels; hence, the chemical and physical properties of the subject hydrogels are homogenous and can be tailored to suit a particular clinical end-point requirement. Furthermore, the hydrogel constructs are mechanically stable because the components are covalently bonded. In addition, the hydrophilicity and flexibility of the porous hydrogel accommodate the absorption of wound exudate and assist the final removal of the material from the wound site (if necessary or desired). The nature of gelatin and the porosity of the construct further facilitate the exchange of gases and allow healing. Most importantly, the presence of hPEG-conjugated bioactive compounds and the loading of other pharmaceutical compounds within the matrix allows for the temporally- and spatially-controlled delivery of bioactive signals to modulate and complement the dynamics of the host healing process. [0015] The present invention offers several key commercial advantages over existing products. For example, despite the extensive investigation in the development of novel wound dressing materials, very few materials are used clinically due to the multiple requirements necessary for a functional wound dressing. Ideal functional wound dressings must be nontoxic, biocompatible, permeable to moisture and gases to absorb wound exudate and toxins, as well as to maintain humidity and oxygen levels. The dressings should be porous to prevent swelling of the wound bed and to prevent accumulation of fluid between the wound site and the material. They should be flexible and durable. They should be biocompatible and minimize local inflammation and infection. They should promote neovascularization, re-epithelialization, and normal healing. The novel multi-functional hydrogels described herein can be made to address all of the above requirements for a clinically viable wound dressing material. [0016] Thus in a first embodiment, the invention is directed to a hydrogel that comprises a polymer matrix. The preferred polymer matrix contains reactive amino groups. The most preferred polymer matrices are gelatin and collagen. The polymer matrix is modified using a bifunctional modifier comprising a poly(alkylene glycol) molecule having a substituted or unsubstituted .alpha.-terminus and a substituted or unsubstituted .omega.-terminus. At least one of the .alpha.- or .omega.-termini is covalently bonded to the polymer matrix. The other terminus projects into the interior of the hydrogel mass and modifies its physico-chemical properties. By controlling the nature of the .alpha.- and .omega.-termini, the physical and chemical qualities of the resulting hydrogel can be altered. [0017] Additionally, in the preferred embodiment, the .alpha.- and .omega.-termini are different, and thus are differentially reactive. This enables, for example, one or more pharmacologically-active agents to be covalently bonded to one of the .alpha.- or .omega.-termini that is not bonded to the polymer matrix. Alternatively (or simultaneously), one or more pharmacologically-active agents may also be entrained within the hydrogel. [0018] The polymer matrix of the hydrogel may be cross-linked with a cross-linking reagent such as glutaraldehyde. Cross-linking alters the absorption characteristics and material strength of the resulting gel. Thus, cross-linking may be desirable where increased mechanical strength of the gel is required. [0019] As noted above, the .alpha.- and/or .omega.-termini of the hydrogel may be substituted or unsubstituted. When substituted, it is preferred that the substitution is a moiety selected from the group consisting of halo, hydroxy, C.sub.1-C.sub.24-alkyl, C.sub.1-C.sub.24-alkenyl, C.sub.1-C.sub.24-alkynyl, C.sub.1-C.sub.24-alkoxy, C.sub.1-C.sub.24-heteroalkyl, C.sub.1-C.sub.24-heteroalkenyl, C.sub.1-C.sub.24-heteroalkynyl, cyano-C.sub.1-C.sub.24-alkyl, C.sub.3-C.sub.10-cycloalkyl, C.sub.3-C.sub.10-cycloalkenyl, C.sub.3-C.sub.10-cycloalkynyl, C.sub.3-C.sub.10-cycloheteroalkyl, C.sub.3-C.sub.10-cycloheteroalkenyl, C.sub.3-C.sub.10-cycloheteroalkynyl, acyl, acyl-C.sub.1-C.sub.24-alkyl, acyl-C.sub.1-C.sub.24-alkenyl, acyl-C.sub.1-C.sub.24-alkynyl, carboxy, C.sub.1-C.sub.24-alkylcarboxy, C.sub.1-C.sub.24-alkenylcarboxy, C.sub.1-C.sub.24-alkynylcarboxy, carboxy-C.sub.1-C.sub.24-alkyl, carboxy-C.sub.1-C.sub.24-alkenyl, carboxy-C.sub.1-C.sub.24-alkynyl, aryl, aryl-C.sub.1-C.sub.24-alkyl, aryl-C.sub.1-C.sub.24-alkenyl, aryl-C.sub.1-C.sub.24-alkynyl, heteroaryl, heteroaryl-C.sub.1-C.sub.24-alkyl, heteroaryl-C.sub.1-C.sub.24-alkenyl, heteroaryl-C.sub.1-C.sub.24-alkynyl, sulfonate, arylsulfonate, and heteroarylsulfonate. [0020] Moreover, these moieties themselves may be further substituted. Thus, the moieties on the .alpha.-terminus and the .omega.-terminus when substituted bear a substituent selected from the group consisting of alkyl, aryl, acyl, halogen, hydroxy, amino, alkoxy, alkylamino, acylamino, thioamido, acyloxy, aryloxy, aryloxyalkyl, mercapto, thia, aza, oxo, saturated cyclic hydrocabon, unsaturated cyclic hydrocarbon, heterocycle, aryl, and heteroaryl. Continue reading about Bifunctional-modified hydrogels... Full patent description for Bifunctional-modified hydrogels Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Bifunctional-modified hydrogels patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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