Biocompatible nano-micro-particles by solvent evaporation from multiple emulsions technique

In this study, a method based on a multiple emulsions system was developed for the production of polymeric nano and micro-vectors. The possibility to apply an unified preparation technique to different polymers, such as polyesters [polycaprolactone, poly-dl-lactide, poly(dl-lactide-co-caprolactone) = 70/30] and polyacrylates [poly(methylmethacrylate-acrylic acid) = 73/27], loaded with different model molecules (budesonide, tamoxifen, and alpha-tocopherol) was explored. After selecting the best operating conditions, especially for emulsification and separation, the technique proved to be readily adaptable for production of both nano and micro-particles with different morphologies, depending on type of polymer, and consequently on solvent used for solubilization: nano-particles, with a round shape and a smooth surface, for polyesters, otherwise micro-particles for the polyacrylate polymer, owing to the presence of hydrophilic co-solvents, that caused both an easy coalescence between the oil and water phases, thus enlarged particles size, and a high porosity. Even the yield of encapsulation was influenced by the presence of hydrophilic co-solvents, causing a higher yield for nano-vectors. Polyesters-based nano-vectors showed release times of molecules, linked to their degradation time, higher than 8 months that make them useful to formulate injectable or implantable drug delivery systems. Polyacrylate-based micro-vectors showed an enteric behavior, interesting for designing solid pharmaceutical formulations for oral delivery. Therefore, the technique demonstrated to assure a broad application in drug delivery research.