Hysteresis in the glucose permeability versus pH characteristic for a responsive hydrogel membrane

A side-by-side diffusion cell was used to study the permeability of glucose through a temperature- and pH-sensitive poly(N-isopropylacrylamide-co-methacrylic acid) hydrogel membrane. At fixed temperature (37 degrees C), lowering pH in one side of the cell induced hydrogel volume collapse and strongly attenuated glucose permeation across the membrane. Hysteresis was observed in the glucose permeability versus pH characteristic.