Our lab usually prepares particles by emulsion, as illustrated here. In the first step (top), an aqueous solution containing particle cargo is added to an organic solution containing the polymer strands that will encapsulate the cargo. As the mixture is stirred (middle), the mixture forms an emulsion: droplets of the aqueous solution are surrounded by the organic solution. To keep the two components from separating, a stabilizer such as polyvinyl alcohol is added (bottom).