Partially biodegradable temperature-and pH-responsive poly(N-isopropylacrylamide)/dextran-maleic acid hydrogels:: formulation and controlled drug delivery of doxorubicin

A new family of partially biodegradable temperature-and pH-responsive hydrogels, poly(N-isopropylacrylamide)/dextran-maleic acid (PNIPAAm/Dex-MA), was synthesized and its application as a drug carrier was investigated. The PNIPAAm/Dex-MA hydrogels were synthesized by UV cross-linking over a wide range of mixed solvent ratios of dimethyl formamide (DMF) to water. PNIPAAm and Dex-MA precursors were chosen as thermo-sensitive and pH-sensitive components, respectively. Dex-MA was also used as a cross-linker. An anti-tumor drug, doxorubicin, was used to examine the effects of network structures of PNIPAAm/Dex-MA hydrogels on the release of drug. These PNIPAAm/Dex-MA hybrid hydrogels exhibited a wide range of porous network structures and sizes due to the effect of the mixed solvent during the gelation reaction. This variation in porous network structure of NDF hydrogels led to a wide range of swelling, deswelling and biodegradation processes. The distinctive porous structure of the PNIPAAm/Dex-MA hydrogels was correlated to the release of doxorubicin from the hydrogels. A larger and faster release of doxorubicin was found in those hydrogels having a large pore size. This new family of PNIPAAm/Dex-MA hydrogels may have a great potential as drug carriers because of their combined stimuli-response capability, as well as partial biodegradability.