Nanosilver Coated Bacterial Cellulose

• US 20090220560A1
• Filed: 04/24/2007
• Published: 09/03/2009
• Est. Priority Date: 04/24/2006
• Status: Active Grant

• Current Assignee: Axcelon Biopolymers Corporation
• Original Assignee: Axcelon Biopolymers Corporation
• Inventors: Guhados, Ganesh, Wan, Wankei
• Granted Patent: US 8,367,089 B2
• Time in Patent Office: Days
• US Class Current: 424/409
• CPC Class Codes: A61L 15/28 Polysaccharides or their derivatives A61L15/225 takes precedence
• CPC Class Codes: A61L 15/46 Deodorants or malodour counteractants, e.g. to inhibit the formation of ammonia or bacteria
• CPC Class Codes: A61L 2300/104 Silver, e.g. silver sulfadiazine
• CPC Class Codes: A61L 2300/404 Biocides, antimicrobial agents, antiseptic agents
• CPC Class Codes: A61L 2300/606 Coatings
• CPC Class Codes: A61L 2300/624 Nanocapsules
• CPC Class Codes: B82Y 5/00 Nanobiotechnology or nanomedicine, e.g. protein engineering or drug delivery
• CPC Class Codes: C08B 15/02 Oxycellulose; Hydrocellulose; Cellulosehydrate, e.g. microcrystalline cellulose
• CPC Class Codes: C08B 15/05 Derivatives containing elements other than carbon, hydrogen, oxygen, halogens or sulfur esters or phosphorous acids C08B5/00
• CPC Class Codes: C08L 1/02 Cellulose; Modified cellulose
• CPC Class Codes: D06M 11/83 with metals; with metal-generating compounds, e.g. metal carbonyls; Reduction of metal compounds on textiles
• CPC Class Codes: D06M 16/00 Biochemical treatment of fibres, threads, yarns, fabrics, or fibrous goods made from such materials, e.g. enzymatic
• CPC Class Codes: D06M 23/08 Processes in which the treating agent is applied in powder or granular form adhesives for multi-layer textile fabrics D06M17/00
• CPC Class Codes: Y10S 977/762 Nanowire or quantum wire, i.e. axially elongated structure having two dimensions of 100 nm or less
• CPC Class Codes: Y10S 977/773 Nanoparticle, i.e. structure having three dimensions of 100 nm or less
• CPC Class Codes: Y10S 977/788 Of specified organic or carbon-based composition
• CPC Class Codes: Y10S 977/81 Of specified metal or metal alloy composition
• CPC Class Codes: Y10S 977/904 for medical, immunological, body treatment, or diagnosis
• CPC Class Codes: Y10T 428/249921 Web or sheet containing structurally defined element or component
• CPC Class Codes: Y10T 428/2927 including structurally defined particulate matter
• CPC Class Codes: Y10T 428/2958 : Metal or metal compound in coating
• CPC Class Codes: Y10T 442/699 : Including particulate material other than strand or fiber material

Abstract

Nanosilver coated bacterial cellulose nanofiber and a method of producing the nanosilver coated bacterial cellulose nanofiber. The nanosilver coated bacterial cellulose nanofiber is produced by preparing a suspension of bacterial cellulose fibers, oxidizing bacterial cellulose fibers; adding the thio-group to the polymer backbone; reacting the resulting product with silver proteinate and enhancing the nanosilver particle size. The nanosilver coated bacterial cellulose nanofibers exhibit antimicrobial properties.

Claims

1. A method of producing nano-silver coated cellulose fibers, comprising:

a) preparing a suspension of cellulose fibers at a pre-selected concentration;

b) exposing the cellulose fibers to an oxidizing agent for oxidizing the cellulose fibers to form dialdehyde cellulose fibers;

c) incorporating a functional group into a backbone of the dialdehyde cellulose fibers to produce functionalized cellulose fibers, the functional group being selected from the group consisting of thio-, aldehyde, ketone and carboxylic acid;

d) exposing the functionalized cellulose fibers to an aqueous solution containing a first silver compound such that nano-silver particles are formed and bound to the cellulose backbone of the functionalized cellulose fibers; and

e) exposing the functionalized cellulose fibers with nano-silver particles bound thereto to a solution containing a second silver compound for growing the nano-silver particles to a pre-selected size.

2. The method according to claim 1 wherein the cellulose fibers are bacterial cellulose nanofibers.

3. The method according to claim 1 wherein the cellulose fibers are microcrystalline cellulose.

4. The method according to claim 1 wherein the cellulose fibers are polysaccharide fibers.

5. The method according to claim 2 wherein the bacterial cellulose nanofibers are derived from a fermentation process and have a diameter in a range from about 10 nm to about 100 nm.

6. The method according to claim 5 wherein the fermentation process is fermentation using Acetobacter xylinum BPR 2001.

7. The method according to claim 1 wherein the aqueous solution containing a first silver compound is a silver proteinate.

8. The method according to claim 7 wherein the silver proteinate is prepared by dissolving 1% wt silver proteinate (SP) and a water soluble borate salt.

9. The method according to claim 8 wherein the boron salt is selected from the group consisting of sodium borate (2%) and other water soluble borate salts.

10. The method according to claim 1 wherein step d) is performed for a length of time selected to give silver nanoparticles having diameter in a range from about 15 nm to about 20 nm.

11. The method according to claim 1 wherein step e) is performed for a length of time selected to give silver nanoparticles having said pre-selected size in a range from about 50 nm to about 100 nm.

12. The method according to claim 1 wherein the solution containing a second silver compound is a silver salt.

13. The method according to claim 12 wherein said silver salt is selected from the group consisting of silver nitrate-ammonia solution, silver sulfate, silver acetate and silver bromide.

14. The method according to claim 1 wherein the oxidizing agent is selected from the group consisting of alkaline metal periodates, gaseous chlorine, hydrogen peroxide, peracetic acid, chlorine dioxide, nitrogen dioxide, persulfates, hypochlorous acid, hypohalites or periodates.

15. The method according to claim 1 wherein step c) of incorporating a functional group into a backbone of the cellulose fibers includes incorporating thio-groups into the backbone, and including reacting the dialdehyde cellulose fibers with a compound having a NH₂—

R—

SH group, where R is an alkyl group.

16. The method according to claim 1 wherein steps b), c), d) and e) are performed on free standing dialdehyde cellulose fibers.

17. The method according to claim 16 wherein said free standing dialdehyde cellulose fibers are treated according to steps c) to e) without drying after being produced in step b).

18. The method according to claim 16 wherein said free standing dialdehyde cellulose fibers are dried after being produced in step b) and then treated according to steps c) to e).

19. The method according to claim 1 wherein after step b) and before step c), forming the dialdehyde cellulose fibers into a sheet of dialdehyde cellulose, then performing steps c), d) and e) on the sheet of dialdehyde cellulose.

20. The method according to claim 19 wherein said sheet of dialdehyde cellulose is treated according to steps c) to e) without having ever been dried after being produced in step b).

21. The method according to claim 19 wherein said sheet of dialdehyde cellulose is dried after being produced and then treated according to steps c) to e).

22. A nanosilver incorporated cellulose fibers with antimicrobial properties prepared according to claim 1.

23. The nanosilver incorporated cellulose fibers according to claim 22 formed into a selected product.

24. The nanosilver incorporated cellulose fibres according to claim 23 wherein the product is a wound dressing.

25. The method according to claim 1 wherein the oxidizing agent is one of sodium periodate, potassium periodate and dinitrogen tetraoxide.