A series of fast pH-responsive silk sericin (SS)/poly(methacrylic acid) (PMAA) IPN hydrogels were prepared by the simultaneous-IPN method. The structure of the resultant IPN hydrogels was characterized by fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The swelling experimental of the IPNs revealed that the hydrogels displayed definite pH sensitivity under physiological conditions, as well as sharp changes in the mesh size of their network as a function of the composition and pH of the swelling media. Bovine serum albumin (BSA) was chosen as a model protein to evaluate the permeation profile through the IPNs in both the simulated gastric and intestinal pH conditions. In all cases, it was found that the release rate of BSA was lower in acidic media (pH 2.6) and higher in basic media (pH 7.4). (C) 2010 Elsevier Ltd. All rights reserved.