Effect of composition on the formation of poly(dl-lactide) microspheres for drug delivery systems: Mesoscale simulations

In this work, the structure–property relationship of drug delivery systems (DDS) is investigated by dissipative particle dynamics (DPD) simulations. Nifedipine is selected as the model drug, whereas poly(dl-lactide) (PLA) as the carrier and polyvinyl alcohol (PVA) as the stabilizer. It is shown from DPD simulations that PLA, drug, and PVA could aggregate and form microspheres under a defined composition recipe; drug molecules are amorphously and homogeneously distributed inside the carrier matrix, on whose surface the stabilizer PVA molecules are adsorbed. Under different compositions of each component, aggregate morphologies of the oil phase are observed as spherical, columnar, and lamellar structures. A phase diagram of DDS has been proposed, which could be used to guide the experimental preparation of DDS with desired properties.