Thermo- and pH-responsive microgels for controlled release of insulin

Microgel particles were prepared, made of hydroxypropylcellulose-graft-(acrylic acid) (HPC-g-AA) and acrylic acid(AA). The particles undergo reversible volume phase transitions in response to both pH and temperature changes while keeping the inherent properties of PAA and HPC-g-AA. Dynamic light scattering measurements reveal that the average hydrodynamic radius and hydrodynamic radius distributions of the microgel particles depend on temperature and pH. The microgels exhibit excellent pH sensitivity and a higher swelling ratio at higher pH in aqueous solution. In vitro release study shows that the amount of insulin released from the microgels is less at pH = 1.2 than at pH = 6.8. The results indicate that the resultant microgels seem to be of great potential for intelligent oral drug delivery. Copyright (c) 2012 Society of Chemical Industry