Electrically controlled release of ibuprofen from conductive poly(3-methoxydiphenylamine)/crosslinked pectin hydrogel
The pristine pectin hydrogels and conductive polymer/hydrogel blends were prepared by the solution casting using ferrous chloride (FeCl2) and citric acid as the crosslinking agents, and ibuprofen as the model drug and the doping agent. A conductive polymer, poly(3-methoxydiphenylamine), was successfully synthesized and embedded into the pristine pectin hydrogels as the drug encapsulation host. The in-vitro release of ibuprofen from the hydrogels was investigated by a modified Franz diffusion cell filled with a MES buffer solution, with pH of 5.5, at 37 °C, for a period of 48 h to investigate the effects of the crosslinking agent type, crosslinking mole ratio, mesh size, electric potential, and conductive polymer. The release behavior of ibuprofen from the pectin hydrogels was found to involve 4 modes of release: Fickian diffusion; Anomalous transport; Case-II transport; and Super case II transport. The diffusion coefficient was shown to be significantly improved by two factors: using a FeCl2 as the crosslinking agent and applied electric potential. For both crosslinking agents, the drug diffusion coefficient increased with decreasing crosslinking ratio. Under electric field of 5 V, the drug diffusion coefficients of the FeCl2 and citric acid hydrogels were enhanced by more than a factor of two due to the electro-repulsive interaction between ibuprofen and the negatively charged electrode. Moreover, the synthesized poly(3-methoxydiphenylamine) embedded in the pectin hydrogels as the drug encapsulation host was shown to enhance the diffusion coefficients and to reduce the overall release times.