Controlled Release from Polyelectrolyte Complex Drug Carriers

Comparison studies of release of a model drug, Rhodamine B, from two different types of polyelectrolyte complex beads (PECs) made of poly(styrenesulfonate, PSS)-poly(allylamine, PAA) and chitosan-alginate were investigated.  The release was carried out by using a modified Franz diffusion cell into deionized water at 37°C.  The long term sustained release (> 7 days) of Rhodamine B was obtained with PSS-PAA PECs due to their tighter networks.  By tuning the compositions of PSS-PAA, the time needed to completely release the drug could be varied from two days to 14 days.  For the case of chitosan-alginate PECs, 100% accumulated release occurred within 24 hours.  With the incorporation of a thermo-responsive polymer, e.g., poly(N-isopropylacrylamine), the release could be extended to two or more days for the chitosan-alginate PECs.  By drying the beads, the release of Rhodamine B was found to be further extended.