Dually responsive microgels from polyether-modified poly(acrylic acid): Swelling and drug loading

Gel microparticles composed of lightly cross-linked poly(acrylic acid) networks, onto which polyether chains (Pluronic F127) are grafted, are introduced. The hydrophobic poly(propylene oxide) chains aggregate within the microgel structure, and the resulting aggregates are capable of solubilizing hydrophobic drugs, such as taxol. At temperatures where the Pluronic chains are not aggregated, the microgels behave like networks without spatial heterogeneity. Upon formation of aggregates within hydrogels, their equilibrium swelling diminishes, and the swelling behavior indicates non-Gaussian chain distribution. The kinetics of gel swelling shows unusual temperature dependence of the effective diffusion coefficient, indicative of chain rearrangement within a certain temperature range. The microgels exhibit high ion-exchange capacity for cationic hydrophilic drugs. The potential for the newly obtained microgels to be used as drug carriers is discussed.