Preparation and Properties of Composite Hydrogels Based on Microgels Containing Chitosan

The microgels were prepared by emulsion polymerization of dimethylacrylamide (DMAA), acrylamide (AAm) and 3-acrylamidephenylboronic acid (AAPBA) in water. Based on the microgel matrix, composite hydrogels were polymerized by adding glutaraldehyde to a chitosan (CS) solution. The microgels were uniformly dispersed in the CS polymer network. Scanning electron microscopy (SEM) indicated a spherical structure of the microgel; the size distribution of the microgel was determined with a Zetasizer with the final average particle size of 59.28 nm. The gel was also characterized by Fourier transform infrared spectroscopy (FTIR) and thermogravimetry analysis (TGA). The water swelling, pH sensitivity and glucose sensitivity of the hydrogels were also studied; we found that the composite hydrogels had a certain responsiveness to glucose at physiological pH with a response time of about 50 min. These observations suggest an excellent prospect for the use of the gel as a self-regulated, insulin-delivery system discretely switching the release at the normoglycemia. It lays the foundations for the gel's use in humans for drug delivery.