Patent US4572906A successfully refreshed from Google Patents.
US4572906A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Chitosan based wound dressing materials
Assignee: Department of National Defence
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Filing: 1984-10-02
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Granted: 1986-02-25
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Expires: 2004-10-02
Abstract
Abstract The invention disclosed is a surgical dressing, particularly useful for the protection of wounds during the healing process. The dressing comprises a blend of gelatin and chitosan in a weight ratio of about 3:1 to 1:3 and a compatible plasticizer in an amount of 0-40% w/w based on the combined weight of gelatin and chitosan.
Inventors
- 👤 Brian G. Sparkes
- 👤 Douglas G. Murray
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:37
CPC Classifications
C; C08; C08L; C08L5/00; C08L5/08; A; A61; A61L; A61L26/00; A61L26/0009; A61L26/0052; C08L89/00; C08L89/04; C08L89/06
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
104 words
A method for making a wound dressing material, said material comprising a blend of gelatin and chitosan in a weight ratio of about 3:1 to 1:3, the method comprising: (a) dissolving the chitosan in distilled water by adding lactic acid or hydrochloric acid in small portions over an extended time period to a stirred suspension of chitosan in water at about room temperature, the acid resulting in a pH in solution of about 2-5, (b) adding the gelatin dissolved in dissolved water, (c) mixing, and (d) adding a basic solution to raise the pH of the mixture so formed to about 5.7 to 6.3.
Claim 2
Independent Claim
104 words
A method for making a wound dressing material, said material comprising a blend of gelatin and chitosan in a weight ratio of about 3:1 to 1:3, the method comprising: (a) dissolving the chitosan in distilled water by adding lactic acid or hydrochloric acid in small portions over an extended time period to a stirred suspension of chitosan in water at about room temperature, the acid resulting in a pH in solution of about 2-5, (b) adding the gelatin dissolved in dissolved water, (c) mixing, and (d) adding a basic solution to raise the pH of the mixture so formed to about 5.7 to 6.3.
Claim 3
Dependent Claim
15 words
A method according to claim 1, wherein the basic solution is 5% aqueous sodium bicarbonate.
Claim 4
Dependent Claim
25 words
A method according to claim 2, including the additional step of (e) adding a compatible plasticizer selected from the group consisting of glycerol and sorbitol.
Claim 5
Dependent Claim
26 words
A method according to claim 3, including the additional step of (f) casting the solution on a flat plate and drying to a continuous wound-adherent film.
Claim 6
Dependent Claim
22 words
A method according to claim 3, including the additional step of (f) coating the solution onto a wound and drying in situ.
Claim 7
Dependent Claim
33 words
A method according to claim 5, which includes the additional step of (g) apply a solution of a non-caustic setting agent onto the freshly applied coating to provide a tough outer gel layer.
Claim 8
Dependent Claim
18 words
A method according to claim 6, wherein the setting agent is selected from zinc acetate and sodium bicarbonate.
Claim 9
Independent Claim
61 words
A method of treating a wound which comprises applying to the wound a wound dressing material in the form of a continuous preformed film, the material comprising a blend of gelatin and chitosan in a weight ratio of about 3:1 to 1:3 and a compatible plasticizer in an amount of 0-40% w/w based on the combined weight of gelatin and chitosan.
Claim 10
Independent Claim
61 words
A method of treating a wound which comprises applying to the wound a wound dressing material in the form of a continuous preformed film, the material comprising a blend of gelatin and chitosan in a weight ratio of about 3:1 to 1:3 and a compatible plasticizer in an amount of 0-40% w/w based on the combined weight of gelatin and chitosan.
Claim 11
Dependent Claim
17 words
The method according to claim 8, wherein the weight ratio of gelatin to chitosan is about 1:1.
Claim 12
Dependent Claim
19 words
The method according to claim 9, wherein the plasticizer is selected from the group consisting of glycerol and sorbitol.
Claim 13
Dependent Claim
31 words
The method according to claim 8, wherein the chitosan is of a viscosity grade of about 630 cp and the gelatin has a bloom number of about 80 to about 350.
Claim 14
Independent Claim
92 words
A method of treating a wound which comprises (1) applying to the wound a coating of an aqueous solution of a burn dressing material comprising a blend of gelatin and chitosan in a weight ratio of about 3:1 to 1:3 and a compatible plasticizer in an amount of 0-40% w/w based on the combined weight of gelatin and chitosan, and allowing the thus applied coating to dry in situ; and (2) applying a solution of a non-toxic setting agent on to the freshly applied coating to provide a tough outer gel layer.
Claim 15
Independent Claim
92 words
A method of treating a wound which comprises (1) applying to the wound a coating of an aqueous solution of a burn dressing material comprising a blend of gelatin and chitosan in a weight ratio of about 3:1 to 1:3 and a compatible plasticizer in an amount of 0-40% w/w based on the combined weight of gelatin and chitosan, and allowing the thus applied coating to dry in situ; and (2) applying a solution of a non-toxic setting agent on to the freshly applied coating to provide a tough outer gel layer.
Claim 16
Dependent Claim
18 words
The method according to claim 12, wherein the setting agent is selected from zinc acetate and sodium bicarbonate.
Claim 17
Dependent Claim
17 words
The method according to claim 12, wherein the weight ratio of gelatin to chitosan is about 1:1.
Claim 18
Dependent Claim
19 words
The method according to claim 12, wherein the plasticizer is selected from the group consisting of gylcerol and sorbitol.
Claim 19
Dependent Claim
31 words
The method according to claim 12, wherein the chitosan is of a viscosity grade of about 630 cp and the gelatin has a bloom number of about 80 to about 350.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1989-02-24 | 1989-08-26 | 1990-02-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-02-24 | 1993-08-26 | 1994-02-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-02-24 | 1997-08-26 | 1998-02-25 | $7700.00 | Window Closed / Lapsed |