Reversible thermal-tunable drug delivery across nano-membranes of hollow PUA/PSS multilayer microcapsules

In this paper, hollow aliphatic poly(urethane-amine) (PUA)/sodium poly(styrene sulfonate) (PSS) multilayer microcapsules with smart nano-membranes were prepared for smart drug delivery. Thanks to the variation of the electrostatic interaction between aliphatic PUA and PSS, and the shrinkage of aliphatic PUA above its LCST, the hollow microcapsules displayed the distinguished pH- and thermal-dependent drug release properties. SEM results indicated that the microcapsule membranes had better thermal-responsiveness at pH 4.5 than that at pH 7.4. More importantly, the microcapsule membranes exhibited reversible thermal-tunable drug release property at pH 4.5 with significant response to temperature change for the sake of the regularly shrinkage of aliphatic PUA above its LCST. The results suggest that the prepared hollow microcapsules can be employed as the novel “smart” nano-membranes for the controllable drug delivery.