Influence of experimental parameters and the copolymer structure on the size control of nanospheres in double emulsion method

Poly(lactide-ethylene glycol) (PLEG) and poly(lactide-methoxy poly(ethylene glycol)) (MePLEG) nanospheres used as drug carrier were prepared by a double emulsion method. The influences of several parameters, such as copolymer structure, phase volume ratios, emulsifer concentration and sonication parameters, on the preparation of these two copolymer nanospheres were investigated for the nanospheres control. Critical values of the emulsifer concentration and the sonication intensity exist, allowing optimization of the nanospheres of controlled size with a narrow distribution. Under the same condition, MePLEG nanospheres had a smaller size than PLEG nanospheres because of their different length of hydrophilic blocks and steric hindrance. In addition, vascular endothelial cell growth factor and cisplatin, as two water-soluble model drugs, were encapsulated in the MePLEG and PLEG nanospheres. A higher encapsulation efficiency, above 90%, of the PLEG nanospheres could be obtained than that of the MePLEG nanospheres because of their different hydrophilic blocks structure.