Triclosan nanoparticles via emulsion-freeze-drying for enhanced antimicrobial activity

Low water solubility and poor bioavailability of hydrophobic pharmaceuticals are significant problems in drug formulation. This research presents a bottom-up route to prepare nanoparticles of hydrophobic actives which is synthetically straightforward, robust, and can be applied to a range of active molecules. A series of amphiphilic branched diblock copolymers have been prepared via the conventional radical polymerization of a vinyl monomer (styrene, butylmethacrylate, or N-isopropylacrylamide) and a corresponding divinyl cross-linker facilitated by a poly(ethylene glycol)-based macro-initiator. These materials were employed as stabilizers in the emulsion-freeze-drying methodology to prepare nanoparticles of hydrophobic pharmaceuticals. It is demonstrated that these branched diblock copolymers are able to facilitate the formation of Triclosan nanoparticles which display enhanced antimicrobial activity against Candida albicans, when compared to non-processed (used as received) Triclosan. This process requires significantly lower levels of stabilizer compared to previously reported surfactant/polymer systems after optimization of polymer properties and morphology.