Oxidized cellulose microspheres

1. A microsphere comprising:

an oxidized cellulose; and

at least one bioactive agent.

2. The microsphere according to claim 1 , wherein the bioactive agent is selected from the group consisting of a hydrophilic bioactive agent, a protein bioactive agent, and combinations thereof.

3. The microsphere according to claim 1 , 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 thereby forming a plurality of microspheres.

4. The microsphere according to claim 3 , wherein the third phase liquid is miscible with the continuous phase liquid and the discontinuous phase liquid.

5. The microsphere according to claim 3 , wherein the third phase liquid is selected from the group consisting of isopropyl myristate, hexane, triglycerides and combinations thereof.

6. The microsphere according to claim 3 , 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.

7. The microsphere according to claim 3 , further comprising forming the oxidized cellulose solution by:

contacting an oxidized cellulose with the solvent under an inert atmosphere to form a swelled oxidized cellulose;

adjusting the swelled oxidized cellulose mixture to a first temperature;

contacting the swelled oxidized cellulose after adjusting the first temperature with a salt under the inert atmosphere to form an oxidized cellulose solution; and

adjusting the oxidized cellulose solution to a second temperature.

8. The microsphere according to claim 7 , wherein the first temperature is from about 115° C. to about 145° C. and the second temperature is from about 90° C. to about 120° C.

9. The microsphere according to claim 7 , wherein the solvent is selected from the group consisting of N,N-Dimethylacetamide, N-methyl-2-pyrrolidinone, and combinations thereof.

10. The microsphere according to claim 7 , wherein the salt is selected from the group consisting of lithium halides, sodium halides, potassium halides, and combinations thereof.

11. The microsphere according to claim 3 , wherein the continuous phase liquid is selected from the group consisting of plant-based oils, petroleum-based oils, silicone-based oils, and combinations thereof.

12. The microsphere according to claim 3 , wherein the third phase liquid is miscible with the continuous phase liquid and immiscible with the discontinuous phase liquid.

13. The microsphere according to claim 3 , wherein the third phase liquid is present in an amount from about 8.33% by volume to about 11.11% by volume of the continuous phase liquid.

14. The microsphere according to claim 1 , wherein the at least one bioactive agent is hydrophobic.