(80d) Encapsulation and Release of Hydrophilic Drug Molecules Via a Poly(lactic acid)-Montmorillorite Composite Micro/Nano-Particle System

Authors: 
Song, A., Michigan State University
Hong, J. S., Soongsil University
Lee, I., Michigan State University
Ji, S., Michigan State University

Poly (lactic acid) (PLA) is one of the most widely used materials to fabricate biodegradable micro/nanoparticle drug delivery carriers.  However, its hydrophobicity limits its application in the encapsulation of hydrophilic drug molecules, like nisin. In our group, a novel dynamic encapsulation process via a single emulsion method has been developed to encapsulate hydrophilic molecules within hydrophobic PLA micro/nano-particles. The uniqueness of this process is the emulsification of PLA solution in the water-glycerol medium under high viscous turbulent shear flow, where water-in-oil-water (W/O/W) droplets formed via one single emulsion step with the high temperature (HT) (60℃) condition, and oil-in-water (O/W) droplets under the room temperature (RT) (25℃) condition. The formation of W/O/W droplets and O/W droplets is reversible between the HT and RT condition, which can be controlled by a cooling circulating system. SEM results showed that open hollow microparticles were obtained under HT condition while nanospheres were prepared under RT condition. By increasing the repeating times of reversible droplets formation, more hydrophilic drug molecules can be encapsulated into the PLA particle matrix. The encapsulation efficiency and release profile will be tested on a series of samples with different repeating times. The addition of montmorillorite (MMT) to PLA is to improve the strength and the biocompatibility of polymer particles. The SEM results showed that more closed hollow microparticles were obtained compared with the samples without MMT. The anti-crack property of the PLA/MMT composite particle may lead to higher encapsulation efficiency because it prevents the breaking leakage of water phase, which contains the hydrophilic drug molecules.