Preparation of Size-Controllable Drug Loaded Nano Particles Based on Flash Nano Precipitation Method

Five amphiphilic diblock copolymers,methoxy poly(ethylene glycol)-b-polycaprolactone (mPEG-b-PCL) with different molecular weights and hydrophilic/hydrophobic proportions were synthesized.A series of nano particles encapsulated model drug beta-carotene and protected by the prepared copolymers as surfactants were prepared by using flash nano-precipitation (FNP) method.The size and size distribution of nano particles were controllable by changing the block structure,molecular weight,polymer concentration and solvent ratio (V(H₂O):V(THF)).Experimental results showed that the size of nano particles decreased by increasing the solvent ratio or hydrophilic proportion.Under the same proportion of the hydrophilic moieties,the size of particles was decreased by increasing the molecular weight.The nano particles became more stable and their size distribution was narrower upon increasing polymer concentrations.