Author S. Niamlang, T. Buranut, A. Niansiri, A. Sirivat
The apparent diffusion coefficients, Dapp, and the release mechanisms of Aloin-doped poly(phenylene vinylene)/polyacrylamide hydrogels, Aloin-doped PPV/PAAM, were investigated. In the absence of an electric field (passive release), the diffusion of Aloin from the SA-doped PPV/PAAM hydrogel is delayed in the first 3- 6 hr due to the ionic interaction between the anionic drug and PPV. Beyond this period, Aloin can diffuse continuously into the buffer solution through the PAAM matrix. Dapp of Aloin-doped PPV/PAAM is higher than that of the Aloin-loaded PAAM, and the former increases with increasing electric field strength due to the combined mechanisms: the expansion of PPV chains inside the hydrogel; the reduction reaction under a negative potential driving the Aloin through the PAAM matrix, or iontophoresis; and the electroporation of the matrix pore. Thus, the presence of the conductive polymer and the applied electric field can be combined to control the drug release rate at an optimal desired level.