Dissolution of oxidized cellulose
A process for dissolving modified cellulose is disclosed. The process includes contacting modified cellulose with a solvent in a mixture to form swelled modified cellulose and then contacting the mixture with a salt to dissolve the swelled modified cellulose.
1. A process comprising:
forming a mixture by contacting an oxidized cellulose with a solvent to form a swelled oxidized cellulose;
adjusting the mixture to a first temperature;
contacting the swelled oxidized cellulose with a salt to form an oxidized cellulose solution; and
adjusting the oxidized cellulose solution to a second temperature lower than the first temperature, wherein dissolved oxidized cellulose of the oxidized cellulose solution retains from about 80% to about 120% of a degree of oxidation of the oxidized cellulose prior to dissolution or from about 80% to about 120% of a molecular weight of the oxidized cellulose prior to dissolution.
2. The process according to claim 1 , wherein the first temperature is adjusted to a temperature of from about 115° C. to about 145° C.
3. The process according to claim 1 , wherein the first temperature is adjusted to a temperature of from about 120° C. to about 140° C.
4. The process according to claim 1 , wherein the first temperature is adjusted to a temperature of from about 130° C. to about 135° C.
5. The process according to claim 1 , wherein the second temperature is adjusted to a temperature of from about 90° C. to about 120° C.
6. The process according to claim 1 , wherein the second temperature is adjusted to a temperature of from about 100° C. to about 110° C.
7. The process according to claim 1 , wherein the solvent is selected from the group consisting of N,N-Dimethylacetamide, N-methyl-2-pyrrolidinone, and combinations thereof.
8. The process according to claim 1 , wherein the salt is selected from the group consisting of lithium halides, sodium halides, potassium halides, and combinations thereof.
9. The process according to claim 1 , wherein the mixture and the oxidized cellulose solution are formed under an inert atmosphere.
10. A process comprising:
forming a mixture by contacting an oxidized cellulose with a solvent to form a swelled oxidized cellulose;
adjusting the mixture to a first temperature;
contacting the swelled oxidized cellulose with a salt to form an oxidized cellulose solution;
adjusting the oxidized cellulose solution to a second temperature lower than the first temperature; and
forming a plurality of microspheres from the oxidized cellulose solution.
11. The process according to claim 10 , further comprising:
forming an emulsion from the oxidized cellulose solution.
12. The process according to claim 11 , further comprising:
contacting the oxidized cellulose solution with at least one bioactive agent to form a discontinuous phase liquid;
contacting the discontinuous phase liquid with a continuous phase liquid to form the emulsion; and
contacting the emulsion with a third phase liquid to extract the solvent from the emulsion, thereby forming a plurality of modified cellulose microspheres.
13. The process according to claim 12 , wherein the continuous phase liquid is selected from the group consisting of plant-based oils, petroleum-based oils, silicone-based oils, and combinations thereof.
14. The process according to claim 12 , wherein the third phase liquid is miscible with the continuous phase liquid and the discontinuous phase liquid.
15. The process according to claim 14 , wherein the third phase liquid is selected from the group consisting of isopropyl myristate, hexane, triglycerides and combinations thereof.
16. The process according to claim 14 , wherein the third phase liquid is present in an amount from about 130% by volume to about 170% by volume of the continuous phase liquid.
17. The process according to claim 10 , wherein the mixture and the oxidized cellulose solution are formed under an inert atmosphere.
18. A microsphere comprising:
solubilized oxidized cellulose having from about 80% to about 120% of a degree of oxidation of undissolved oxidized cellulose prior to dissolution or from about 80% to about 120% of a molecular weight of the undissolved oxidized cellulose prior to dissolution; and
at least one bioactive agent.
19. The microsphere according to claim 18 , wherein the bioactive agent is selected from the group consisting of a hydrophilic bioactive agent, a protein therapeutic, a biologic, and combinations thereof.
20. The microsphere according to claim 18 , wherein the microsphere is formed by:
contacting an oxidized cellulose solution comprising a solvent with the at least one bioactive agent to form a discontinuous phase liquid;
contacting the discontinuous phase liquid with a continuous phase liquid to form an emulsion; and
contacting the emulsion with a third phase liquid to extract the solvent from the emulsion.
21. The microsphere according to claim 20 , wherein the third phase liquid is miscible with the continuous phase liquid and the discontinuous phase liquid.
22. The microsphere according to claim 20 , wherein the third phase liquid is selected from the group consisting of isopropyl myristate, hexane, triglycerides and combinations thereof.