Cellulose hydrogel compositions and contact lenses for corneal applications
The present invention provides cellulose hydrogels having one or more of the following properties: high water content, high transparency, high oxygen permeability, high biocompatibility, high tensile strength and desirable thermal stability. The present invention further provides a process for preparing a cellulose hydrogel comprising (i) a step of activating cellulose, in which the activating step comprises contacting the cellulose with a solvent to activate the cellulose for a time duration from about 2 hours to about 30 hours; (ii) substantially dissolving the activated cellulose to form a solution; and (iii) gelling the solution to form a gel, in which the gelling step comprises allowing the solution to gel in an environment comprising a relative humidity from about 30% to about 80% at 35° C.
1. A wet cellulose hydrogel, comprising: a cellulose content from about 1% to about 10% by weight; said cellulose hydrogel comprising (a) a tear strength of from about 0.8 N/mm to about 3 N/mm and (b) a Young's modulus of from about 900 kPa to about 1600 kPa; said cellulose hydrogel further comprising one or more properties selected from the group consisting of (i) a tensile strength in the range of from about 50 kPa to about 4000 kPa; (ii) a transparency that exceeds 85% at 550 nm; and (iii) an oxygen permeability from about 55 to about 150 Dk.
2. The hydrogel of claim 1 , wherein the cellulose content comprises from about 2% to about 7%.
3. The hydrogel of claim 1 , wherein cellulose content comprises from about 2% to about 5%.
4. The hydrogel of claim 1 , wherein the cellulose content comprises a denaturation temperature of at least about 70° C.
5. The hydrogel of claim 4 , wherein the cellulose hydrogel comprises each of the following (1) the tensile strength comprises from about 625 kPa to about 3500 kPa; (2) the transparency exceeds 90% at 550 nm; (3) the denaturation temperature exceeds 200° C. and is less than 330° C.; and (4) the oxygen permeability comprises from about 55 to about 130 Dk.
6. The hydrogel of claim 5 , wherein the denaturation temperature exceeds about 250° C. and less than about 300° C.
7. The hydrogel of claim 1 , wherein the hydrogel further comprises a strain to failure of from about 40% to about 160%.
8. The hydrogel of claim 1 , wherein the hydrogel further comprises a suture retention strength of from about 0.1 N/mm to about 3.5 N/mm.
9. The hydrogel of claim 1 , wherein the hydrogel further comprises a puncture resistance of from about 100 kPa to about 300 kPa.
10. The hydrogel of claim 1 , wherein the hydrogel is in the shape of a contact lens.
11. The hydrogel of claim 1 , wherein the cellulose is from a source selected from the group consisting of plant, wood pulp, cotton pulp, microbial, and combinations thereof.
12. The hydrogel of claim 1 , wherein the hydrogel comprises one or more cellulose fiber layers.
13. The hydrogel of claim 1 , wherein the transparency of the hydrogel is at least 95% at 550 nm.
14. The hydrogel of claim 1 , wherein the hydrogel has a thickness of from about 50 to about 250 microns.
15. The hydrogel of claim 1 , wherein the hydrogel has a refractive index of from about 1.30 to about 1.50.
16. The hydrogel of claim 1 , wherein the hydrogel comprises bacterial cellulose.
17. A wet cellulose hydrogel, comprising: a cellulose content from about 1% to about 10% by weight; said cellulose hydrogel comprising (a) a tear strength of from about 0.8 N/mm to about 3 N/mm; (b) Young's modulus of from about 900 kPa to about 1600 kPa; and (c) an oxygen permeability from about 55 to about 150 Dk.
18. The hydrogel of claim 17 , wherein said hydrogel comprises a tear strength of from about 1.0 N/mm to about 3 N/mm and a Young's modulus of from about 1000 kPa to about 1600 kPa.
19. The hydrogel of claim 17 , wherein said hydrogel comprises a tear strength of from about 1.5 N/mm to about 3 N/mm.
20. The hydrogel of claim 19 , wherein the hydrogel comprises a Young's modulus of from about 1000 kPa to about 1600 kPa.