Preparation and characterization of a prolonged and sustained drug delivery system: Linear polyacrylamide in poly(N-isopropylacrylamide)/clay hydrogels

In this contribution, a novel smart drug delivery system based on poly(N-isopropylacrylamide) (PNIPAAm), clay, and linear polyacrylamide (PAAm) was developed for prolonged and sustained controlled drug release. Various amounts linear PAAm were incorporated into PNIPAAm/clay hydrogels. Resulting hydrogels were characterized by scanning electron microscopy, differential scanning calorimetry, and compression measurements to investigate the morphological, thermal, and mechanical properties. The swelling ratio and response kinetics on heating or cooling were also investigated to understand the smart properties. Finally, bovine serum albumin (BSA), used as the model drug, was loaded into the hydrogels to examine and compare the effects of controlled release at different temperatures (20 degrees C and 37 degrees C). The result indicated that all the PNIPAAm/clay/linear PAAm gels showed good smart property with a higher swelling ratio and more complicated deswelling behavior. Although the compression properties of the resulting hydrogels decreased by incorporating the linear PAAm into the network of PNIPAAm/clay, they still showed high compression stress and excellent reversibility. BSA release behavior at 20 degrees C and 37 degrees C revealed that a prolonged release of BSA with the auto-adjustable function to external temperature changes. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012