Since its first report, the manufacturing technique has evolved into two subgroups, referred to as single and double emulsion solvent evaporation methods. In cases where the active molecule or polymer has a lower solubility in aqueous environments, a single emulsion solvent evaporation technique is preferred. As the name implies, this synthesis method involves a single W/O emulsion and is therefore no different from the method described in the previous section . The double emulsion evaporation technique, on the other hand, is specifically used for the encapsulation of molecules with high water solubility in water. In this method, an aqueous solution of a drug is dispersed in an organic solution with a polymer, forming a primary (W/O) emulsion. This emulsion is then dispersed in a second aqueous solution containing a suitable phospholipid; thus, a double emulsion (W/O/W) is formed. Once drugs or biomolecules are encapsulated in CSHNs, the organic solvent is removed and the product is isolated .