pH- and temperature-sensitive permeation through polyelectrolyte complex films composed of chitosan and polyalkyleneoxide–maleic acid copolymer

The pH- and temperature-effects on drug permeation from polyelectrolyte complex (PEC) films composed of a cationic polymer, chitosan (CS) and an anionic polymer, polyalkyleneoxide–maleic acid copolymer (PAOMA), have been investigated. In this study, we prepared and investigated PEC films for utility as on–off switches in drug transport. PEC films were prepared by a casting/solvent evaporation method. PEC films swelled at low pH and low temperature. This swelling behavior was reversible with the films responding rapidly to a change in environmental pH and temperature. Drug permeation rates were tested with pH 3.8 and 6.2 at 25 and 50 °C. Salicylic acid, phenol and glucose were selected as model drugs to examine the effect of molecular weight. A decrease in pH from 6.2 to 3.8 and an increase in temperature from 25 to 50 °C resulted in a corresponding increase in the rate of drug permeation. Of the three model drugs tested, glucose, with the highest molecular weight showed the lowest effective diffusion coefficient.