US5948432A
Expired / Lapsed
US
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Keratin-based sheet material for biomedical applications and method of production
Assignee: Keraplast Technologies Ltd
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Filing: 1997-11-26
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Granted: 1999-09-07
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Expires: 2017-11-26
Abstract
Abstract A sheet wound dressing formed of cross linked keratin. An insoluble, largely Beta keratin fraction from human hair is acidified to a low pH, preferably less than about 3, which partially solubilizes the keratin by weakening hydrogen bonds. The suspension is added to base, such as ammonium hydroxide, forming a slurry. The slurry is cast directly onto a flat surface, allowing the re-formation of cross-links including hydrogen bonds and disulfide bonds. The resulting cross-linked keratin sheet can be used as a sheet wound dressing or as a scaffolding for growth of cells. The insoluble keratin can be derived from human hair which is washed, rinsed, dried, chopped and treated with peracetic acid to break some accessible disulfide linkages. The treated hair is filtered, rinsed, dried, and ground into a keratin powder. The keratin powder is suspended in a mixture of ammonium hydroxide and ammonium thioglycollate and heated sufficiently to dissolve the soluble keratin fraction, followed by cooling and centrifugation to concentrate the insoluble, largely Beta keratin fraction.
Inventors
- 👤 Scott F. Timmons
- 👤 Cheryl R. Blanchard
- 👤 Robert A. Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:06
CPC Classifications
C; C12; C12N; C12N5/00; C12N5/0068; A; A61; A61K; A61K35/00; A61K35/12; A61K35/36; A61K38/00; A61K38/16; A61K38/17; A61K38/1703; A61K38/1709; A61K38/39; A61K9/00; A61K9/70; A61L; A61L15/00; A61L15/16; A61L15/22; A61L15/32; A61L26/00; A61L26/0009; A61L26/0028; A61L26/0047; A61L26/0061; A61L26/008; A61L27/00; A61L27/14; A61L27/22; A61L27/227; A61L27/28; A61L27/34; A61L27/50; A61L27/60; A61L31/00; A61L31/04; A61L31/043; A61L31/047; A61L31/08; A61L31/10; C07; C07K; C07K14/00; C07K14/435; C07K14/46; C07K14/47; C07K14/4701; C07K14/4741; C08; C08H; C08H1/00; C08H1/06; C12N2533/00; C12N2533/50; Y; Y10; Y10S; Y10S530/00; Y10S530/827; Y10S530/842
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
32 words
A sheet wound dressing comprising a keratin sheet having added hydrophilic groups bound to said keratin, wherein said keratin sheet is bound together with bonds consisting essentially of keratin to keratin bonds.
Claim 2
Dependent Claim
32 words
A sheet wound dressing comprising a keratin sheet having added hydrophilic groups bound to said keratin, wherein said keratin sheet is bound together with bonds consisting essentially of keratin to keratin bonds.
Claim 3
Dependent Claim
15 words
A sheet wound dressing as recited in claim 1, wherein said keratin sheet includes water.
Claim 4
Dependent Claim
17 words
A sheet wound dressing as recited in claim 1, wherein said keratin is cross-linked without a binder.
Claim 5
Dependent Claim
16 words
A sheet wound dressing as recited in claim 1, wherein said keratin comprises primarily Beta keratin.
Claim 6
Dependent Claim
17 words
A sheet wound dressing as recited in claim 1, wherein said keratin is derived from vertebrate hair.
Claim 7
Dependent Claim
17 words
A sheet wound dressing as recited in claim 5, wherein said keratin is derived from human hair.
Claim 8
Dependent Claim
22 words
A sheet wound dressing as recited in claim 5, wherein said keratin is derived primarily from the cuticle structure of hair shafts.
Claim 9
Dependent Claim
22 words
A keratin sheet as recited in claim 1, wherein said added hydrophilic groups include sulfonic acid groups formed from oxidized disulfide bonds.
Claim 10
Dependent Claim
68 words
A process for forming a sheet wound dressing comprising the steps of: providing a keratin fraction insoluble in water at neutral pH and room temperature; suspending said keratin fraction in an acid having sufficiently low pH to at least partially unfold said keratin, thereby forming a keratin suspension; adding a base to said keratin suspension, thereby creating a keratin slurry; and forming said keratin slurry into a sheet.
Claim 11
Dependent Claim
68 words
A process for forming a sheet wound dressing comprising the steps of: providing a keratin fraction insoluble in water at neutral pH and room temperature; suspending said keratin fraction in an acid having sufficiently low pH to at least partially unfold said keratin, thereby forming a keratin suspension; adding a base to said keratin suspension, thereby creating a keratin slurry; and forming said keratin slurry into a sheet.
Claim 12
Dependent Claim
28 words
A process for forming a sheet wound dressing as recited in claim 9 wherein said keratin fraction is insoluble in water at all pHs between 1 and 14.
Claim 13
Dependent Claim
31 words
A process for forming a sheet wound dressing as recited in claim 9 wherein said insoluble keratin fraction remains insoluble after oxidation with peracetic acid and reduction with alkaline ammonium thioglycollate.
Claim 14
Dependent Claim
25 words
A process for forming a sheet wound dressing as recited in claim 9, wherein said forming step includes casting said slurry onto a flat surface.
Claim 15
Dependent Claim
24 words
A process for forming a sheet wound dressing as recited in claim 9, wherein said keratin slurry has a pH greater than about 6.
Claim 16
Dependent Claim
21 words
A process for forming a sheet wound dressing as recited in claim 9, wherein said keratin is derived from human hair.
Claim 17
Dependent Claim
37 words
A process for forming a sheet wound dressing as recited in claim 9, wherein said acid is selected from the group consisting of concentrated sulfuric acid and formic acid and having a pH less than about 6.
Claim 18
Dependent Claim
28 words
A process for forming a sheet wound dressing as recited in claim 9, wherein said base is ammonium hydroxide having a concentration of at least 1×10 -5 M.
Claim 19
Dependent Claim
61 words
A process for forming a sheet wound dressing comprising the steps of: providing a keratin fraction insoluble in water at room temperature at all pHs between 1 and 14; suspending said keratin fraction in a volatile acid having sufficiently low pH to partially unfold said keratin protein, such that a slurry is formed; and forming said keratin slurry into a sheet.
Claim 20
Dependent Claim
61 words
A process for forming a sheet wound dressing comprising the steps of: providing a keratin fraction insoluble in water at room temperature at all pHs between 1 and 14; suspending said keratin fraction in a volatile acid having sufficiently low pH to partially unfold said keratin protein, such that a slurry is formed; and forming said keratin slurry into a sheet.
Claim 21
Dependent Claim
71 words
A process for forming a sheet wound dressing comprising the steps of: providing a keratin fraction insoluble in water at room temperature at all pHs between 1 and 14; suspending said keratin fraction in a non-volatile acid having sufficiently low pH to partially unfold said keratin protein, such that a slurry is formed; exchanging the non-volatile acid by treatment with a volatile base; and forming said keratin slurry into a sheet.
Claim 22
Dependent Claim
71 words
A process for forming a sheet wound dressing comprising the steps of: providing a keratin fraction insoluble in water at room temperature at all pHs between 1 and 14; suspending said keratin fraction in a non-volatile acid having sufficiently low pH to partially unfold said keratin protein, such that a slurry is formed; exchanging the non-volatile acid by treatment with a volatile base; and forming said keratin slurry into a sheet.
Claim 23
Dependent Claim
62 words
A keratin sheet formed by the steps comprising: providing a keratin fraction insoluble in water at room temperature and neutral pH; suspending said keratin fraction in an acid having sufficiently low pH to partially unfold said keratin, thereby forming a keratin suspension; adding a base to said keratin suspension, thereby creating a keratin slurry; and forming said keratin slurry into a sheet.
Claim 24
Dependent Claim
62 words
A keratin sheet formed by the steps comprising: providing a keratin fraction insoluble in water at room temperature and neutral pH; suspending said keratin fraction in an acid having sufficiently low pH to partially unfold said keratin, thereby forming a keratin suspension; adding a base to said keratin suspension, thereby creating a keratin slurry; and forming said keratin slurry into a sheet.
Claim 25
Dependent Claim
15 words
A keratin sheet as recited in claim 19, wherein said keratin is primarily Beta keratin.
Claim 26
Dependent Claim
23 words
A keratin sheet as recited in claim 19 wherein said keratin fraction is insoluble in water at all pHs between 1 and 14.
Claim 27
Dependent Claim
26 words
A keratin sheet as recited in claim 19 wherein said insoluble keratin fraction remains insoluble after oxidation with peracetic acid and reduction with alkaline ammonium thioglycollate.
Claim 28
Dependent Claim
18 words
A keratin sheet as recited in claim 19, wherein said suspension has a pH less than about 6.
Claim 29
Dependent Claim
18 words
A keratin sheet as recited in claim 19, wherein said slurry has a pH greater than about 7.
Claim 30
Dependent Claim
57 words
A keratin sheet formed by the steps comprising: providing a keratin fraction insoluble in water at room temperature at all pHs between 1 and 14; suspending said keratin fraction in a volatile acid having sufficiently low pH to partially unfold said keratin protein, such that a slurry is formed; and forming said keratin slurry into a sheet.
Claim 31
Dependent Claim
57 words
A keratin sheet formed by the steps comprising: providing a keratin fraction insoluble in water at room temperature at all pHs between 1 and 14; suspending said keratin fraction in a volatile acid having sufficiently low pH to partially unfold said keratin protein, such that a slurry is formed; and forming said keratin slurry into a sheet.
Claim 32
Dependent Claim
67 words
A keratin sheet formed by the steps comprising: providing a keratin fraction insoluble in water at room temperature at all pHs between 1 and 14; suspending said keratin fraction in a non-volatile acid having sufficiently low pH to partially unfold said keratin protein, such that a slurry is formed; exchanging the non-volatile acid by treatment with a volatile base; and forming said keratin slurry into a sheet.
Claim 33
Dependent Claim
67 words
A keratin sheet formed by the steps comprising: providing a keratin fraction insoluble in water at room temperature at all pHs between 1 and 14; suspending said keratin fraction in a non-volatile acid having sufficiently low pH to partially unfold said keratin protein, such that a slurry is formed; exchanging the non-volatile acid by treatment with a volatile base; and forming said keratin slurry into a sheet.
Claim 34
Dependent Claim
51 words
A sheet wound dressing formed by the steps comprising: providing a keratin slurry, wherein said keratin is primarily Beta keratin, wherein said keratin has a plurality of --CH 2 SH groups that will form disulfide linkages within days; and forming said slurry into a sheet, such that said disulfide linkages form.
Claim 35
Dependent Claim
51 words
A sheet wound dressing formed by the steps comprising: providing a keratin slurry, wherein said keratin is primarily Beta keratin, wherein said keratin has a plurality of --CH 2 SH groups that will form disulfide linkages within days; and forming said slurry into a sheet, such that said disulfide linkages form.
Claim 36
Dependent Claim
25 words
A keratin sheet formed by the steps comprising: providing a cross-linkable keratin slurry; and forming said slurry into a sheet, such that said keratin cross-links.
Claim 37
Dependent Claim
25 words
A keratin sheet formed by the steps comprising: providing a cross-linkable keratin slurry; and forming said slurry into a sheet, such that said keratin cross-links.
Claim 38
Dependent Claim
15 words
A keratin sheet as recited in claim 28 wherein said keratin is primarily Beta keratin.
Claim 39
Dependent Claim
17 words
A keratin sheet as recited in claim 28 wherein said keratin is at least 10% Beta keratin.
Claim 40
Dependent Claim
17 words
A keratin sheet as recited in claim 30 wherein said keratin is at least 80% Beta keratin.
Claim 41
Dependent Claim
20 words
A keratin sheet dressing as recited in claim 28 wherein said forming includes casting said keratin onto a flat surface.
Claim 42
Dependent Claim
25 words
A keratin sheet dressing as recited in claim 28 wherein said forming includes casting said keratin into a mold of appropriate geometry and surface finish.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-09-06 | 2003-03-08 | 2003-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-09-06 | 2007-03-08 | 2007-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-09-06 | 2011-03-08 | 2011-09-07 | $7700.00 | Window Closed / Lapsed |