Degradation of hydrolyzable hydrogel microspheres

This work aims to monitor the hydrolysis of microspheres made of synthetic degradable hydrogels. Well spherical microspheres incorporating hydrolyzable crosslinkers inside their structure were first synthesized by direct suspension polymerization. Their elastic properties evaluated prior to degradation by a rheological method show that microspheres behave like nearly pure elastic material with an elastic modulus varying from 2 to 11 kPa according to their composition. The pH, swelling and rheological properties were used to follow microsphere modifications during hydrolysis. Results obtained over a period of 60 days revealed that microspheres were only partially degraded under the experimental conditions used. After this period, microspheres were highly swollen with a low elastic modulus (ranging from 0.17 to 0.83 kPa) compared to the starting material. The hydrolytic degradation rate could be tuned by modulating the crosslinking degree and the chemical structure of the degradable crosslinker included in the hydrogel network.