6.3.4.2　Self-emulsion/solvent diffusion method

A mixed solvent composed of a water-insoluble organic solvent and a water-soluble organic solvent（e.g.，acetone，methanol）is used for the oil phase.After mixing with water，the water-soluble organic solvent spreads spontaneously from oil phase into aqueous phase，hence the turbulence occurs at the two-phase interface，resulting in the generation of droplets and eventually forming NPs of polymers and drugs after solvent evaporation.The advantage of this method is that no surfactant is required，but the uniformity of nano-drug carriers are not as good as that of emulsion-solvent evaporation method.PLA nano-spherical drug carriers loading insoluble drug oridonin（ORI）were prepared by this method，whose average size is 137.3 nm，the encapsulation efficiency is 91.88％±1.83％，and drug loading is 2.32％±0.05％.(https://www.daowen.com)