Optimized formulation of high-payload PLGA nanoparticles containing insulin-lauryl sulfate complex

A novel poly(lactic acid-co-glycolic acid) nanoparticle loaded with insulin-lauryl sulfate complex was prepared by spontaneous emulsion solvent diffusion method. The effects of key parameters such as agitation speed, poly(vinyl alcohol) concentration, solvent composition, polymer concentration, and the volume of external aqueous phase on the properties of the nanoparticles were investigated. To enhance the drug recovery and drug content simultaneously, a response surface methodology with five-level, two-factor central composite design was employed. The weight ratio of polymer to drug and volume ratio of external aqueous phase to solvent phase were selected as controlled factors on account of their interactions found in the monofactorial investigations. The experimental datum allowed the development of quadratic models (p < .05) describing the inter-relationships between the dependent and independent variables. By solving the regression equation, and graphic analyzing the response surface contour and plots, the optimum values of the two factors were determined as 20/1 and 10/1. The optimized conditions led to 89.6% of drug recovery and 4.57% of drug content during nanoparticle preparation.