Partially biodegradable temperature and pH sensitive hydrogel

1. Hydrogel that changes its shape and volume in response to change in pH and in response to change in temperature, formed by photocrosslinking of dextran-maleic acid monoester and N-isopropylacrylamide in a composition comprising from 10 to 75% by weight dextran-maleic monoester and from 90 to 25% by weight N-isopropylacrylamide, with the total of the dextran-maleic acid monoester and N-isopropylacrylamide being 100%.

2. The hydrogel of claim 1 which is formed by photocrosslinking dextran-maleic acid monoester and N-isopropylacrylamide in a composition comprising from 20 to 65% by weight dextran-maleic acid monoester and from 80 to 35% by weight N-isopropylacrylamide.

3. The hydrogel of claim 2 where the dextran-maleic acid monoester has an average degree of substitution ranging from 0.85 to 0.95 and a weight average molecular weight ranging from 65,000 to 75,000 on a dextran basis.

4. The hydrogel of claim 3 which has a lower critical solution temperature which is less than or near body temperature.

5. A hydrogel forming system comprising a solution of from 10 to 75% by weight dextran-maleic acid monoester and from 90 to 25% by weight N-isopropylacrylamide based on the total of the dextran-maleic acid monoester and the N-isopropylacrylamide being 100%.

6. Hydrogel formed by photocrosslinking of dextran-maleic acid monoester and N-isopropylacrylamide in a composition comprising from 10 to 75% by weight dextran-maleic acid monoester to provide functionality for the hydrogel to change shape and volume in response to pH change and from 90 to 25% by weight N-isopropylacrylamide to provide functionality for the hydrogel to change shape and volume in response to temperature change, the total of the dextran-maleic acid monoester and N-isopropylacrylamide being 100%.