Hydrogel wound dressing and biomaterials formed in situ and their uses
Inventors
St. John, John • Moro, Daniel G.
Assignees
Publication Number
US-7910135-B2
Publication Date
2011-03-22
Expiration Date
2026-10-13
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Abstract
The present invention relates to a method of forming shape-retentive and shape-conforming aggregate wound dressings and biomaterials composed of gel nanoparticles and wound or bodily fluid in which the aggregates are held together by non-covalent bond physical forces such as, without limitation, hydrophobic-hydrophilic interactions and hydrogen bonds. The method comprises introducing a dry powder of gel nanoparticles to a wound site in which the nanoparticles absorb some of the blood or wound exudate and coalesce in situ into the claimed shape-retentive aggregate dressing. The method also comprises introducing the dry nanoparticle powder in or on a wet bodily tissue in vivo to form the claimed shape-retentive biomaterial. In addition, the method also comprises incorporating biomedical agents to produce medicated aggregate dressings or biomaterials for a variety of medical applications. This invention also relates to uses of the method of formation of the shape-retentive aggregates of gel nanoparticles.
Core Innovation
The invention relates to a method of forming shape-retentive and shape-conforming aggregate wound dressings and biomaterials composed of gel nanoparticles and wound or bodily fluid, wherein the aggregates are held together by non-covalent bond physical forces such as hydrophobic-hydrophilic interactions and hydrogen bonds. The method involves introducing a dry powder of gel nanoparticles onto a wet wound site or bodily tissue where the nanoparticles absorb fluids like blood or exudate and coalesce in situ into shape-retentive aggregates that conform to the wound or tissue shape.
The problem addressed arises from limitations of existing wound dressings, which include failure to absorb exudates adequately, poor conformity to irregular wound shapes, difficulty in removal without damaging new tissue, and insufficient control over drug release. Bulk hydrogels provide shape-retentiveness but have slow swelling and release rates, while particulate gels allow controlled release but lack shape-retentiveness and localization.
This invention combines the advantageous properties of bulk hydrogels and particulate gels by using nanoparticles polymerized from specific monomers containing hydroxy and/or ester groups. These nanoparticles form a dry powder that, upon application to wet wounds or tissues, absorb fluids and form an integral, shape-retentive, non-occlusive dressing or biomaterial through physical interactions. Additionally, the method allows incorporation of biomedical or pharmaceutical agents for sustained controlled release to aid wound healing and other medical applications.
Claims Coverage
The patent includes 48 claims with one main independent claim and several dependent claims. Three further independent claims relate to methods of forming wound dressings or biomaterials in situ and methods of treatment.
Dry powder of polymeric nanoparticles forming shape-retentive aggregates
A dry powder comprising polymeric nanoparticles formed by polymerizing monomers selected from 2-alkenoic acids, hydroxy or alkoxy substituted alkyl 2-alkenoates, and vicinyl epoxy alkyl 2-alkenoates in a polar liquid with surfactant, producing nanoparticles with average diameter from about 20 to 300 nm, followed by removal of liquid to less than 10% by weight while preventing aggregation.
Shape-conforming aggregate dressing formation in situ
Applying the dry powder of polymeric nanoparticles onto a wet wound site, causing absorption of wound fluid and coalescence into a shape-retentive, shape-conforming aggregate dressing held by non-covalent forces including hydrophobic-hydrophilic interactions and hydrogen bonds.
Formation of shape-retentive biomaterial in vivo
Applying the dry powder of polymeric nanoparticles onto or in wet bodily tissue in vivo, resulting in absorption of bodily fluid and coalescence into a shape-retentive, shape-conforming biomaterial aggregate held together by similar non-covalent interactions.
Use of working substances occluded or entrapped in nanoparticles and aggregates
Incorporation of working substances including biomedical agents, pharmaceutical agents, tissue scaffold materials, cells, platelets, and growth factors either occluded during polymerization or dry blended after nanoparticle formation, enabling controlled release within the formed aggregates.
The independent claims cover the dry polymeric nanoparticle powder composition, methods of forming shape-retentive wound dressings and biomaterials by applying the dry powder to wet wounds or tissues, and methods of treating wounds by this application. The inventive features focus on the nanoparticle composition, their in situ aggregation via non-covalent forces when exposed to physiological fluids, and incorporation of therapeutic agents for controlled release.
Stated Advantages
The dressings provide adequate oxygenation due to their porous, non-occlusive nature.
They protect wounds from exogenous bacteria and eliminate infection potential by utilizing the wound's exudate in dressing formation.
The aggregates conform precisely to wound or tissue shapes maintaining shape-retention until healing completion.
They allow sustained and controlled release of therapeutic compounds over prolonged periods.
The powders are dry and stable for extended storage and ease of application.
The aggregates require no secondary dressings, reduce inflammation and shedding, and improve patient acceptability.
Documented Applications
Wound dressings for exuding wounds including burns, dermabrasions, skin donor sites, punch biopsies, decubitus and vascular ulcers.
Medicated dressings incorporating antibiotics, analgesics, growth factors for enhanced wound healing and infection control.
Biomaterial formation in vivo for orthopedic applications such as cartilage and bone repair, meniscus repair, artificial spinal discs, tendons, ligaments, and bone defect fillers.
Soft drug delivery devices formed in situ like moldable drug-eluting contact lenses, ocular drug delivery implants placed behind the eye, and drug-releasing periodontal pocket fillings.
Use as carriers for metals or metal ions to confer conductivity or radiopacity for wound healing stimulation or other uses requiring electrical properties.
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