Protein Release From Chemically Degrading Dextran Hydrogels

PROTEIN RELEASE FROM CHEMICALLY DEGRADING DEXTRAN HYDROGELS 

In dex-MA (Fig.2) methacrylate esters are present which are sensitive to hydrolysis However, in hydrogels derived from dex-MA no significant hydrolysis of ester group occurs, even at extreme conditions (pH and temperature). As shown in the previous section, dex-MA can be rendered 

L-lactide (2) is grafted onto HEMA (1), yielding HEMA-lactate (3). After activation with A,A -carbonyldiimidazole (GDI, 4), the resulting 

HEMA-lactate-CI (5) is coupled to dextran (7) to yield dex-laetateHEMA (8) (Fig. 8). A comparable dextran derivative without lactate spacer between the methacrylate ester and dextran was also synthesized. For this compound, HEMA was activated with CDl, and the resulting HEMA-Cl (9) is then coupled to dextran, yielding dexHEMA (10) (Fig. 9). 

From this figure it appears that for gels with a high initial water content a first order release of the protein is observed (diffusion controlled release), whereas for gels with a lower initial water content an almost zero order release is observed for 35 days (degradation controlled release). 

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