Effects of preparation conditions on the characteristics of poly(lactide-co-glycolide) nanospheres loaded with chloro(5,10,15,20-tetraphenylporphyrinato)indium(III).

A 2(4-1) fractional factorial design was utilized to evaluate the influence of four preparation conditions on six characteristics of poly(lactide-co-glycolide) nanospheres loaded with chloro(5,10,15,20-tetraphenylporphyrinato)indium(III). Ethanol in the aqueous phase and the stirring rate were the factors that most influenced the nanosphere characteristics. An increase in these factors caused a decrease in nanosphere size, recovery yield and residual chloroform and an increase in the percent of residual poly(vinyl alcohol). The synergic interaction between these two factors caused an increase in the percent residual chloroform. The entrapment efficiency was increased by an increase of ethanol in the aqueous phase or an increase in the percent poly(vinyl alcohol), but an overall decrease was obtained due to a synergic interaction between these factors. The stirring rate was the only parameter that caused an increase of the zeta potential. Evolutionary operations were then carried out based on the results from the fractional factorial design and nanospheres were obtained with sizes smaller than 200 nm.