Optimization of protein encapsulation in PLGA nanoparticles

Influences of process parameters were investigated on the efficiency of encapsulation of bovine serum albumin (BSA) in poly(dl-lactic-co-glycolic acid) (PLGA) nanoparticles produced by w1/o/w2 (water-in-oil-in-water) double emulsion-solvent evaporation method. According to a 5-factorial 3-level Box–Behnken type experimental design aqueous solution of BSA was emulsified in an immiscible organic phase composed of dichloromethane and various quantities of dissolved PLGA to get water-in-oil (w1/o) emulsion. This latter was then dispersed in a second aqueous phase (w2) containing poly-vinyl-alcohol (PVA) surfactant as an emulsifier/stabilising agent. PLGA nanoparticles with encapsulated BSA were obtained by evaporating the dichloromethane from the w1/o droplets. Encapsulation efficiency was determined as the weight ratio of BSA remained in the PLGA nanoparticles relative to the total weight of BSA used in the process. By statistical evaluation of the experimental results an equation was proposed to predict the encapsulation efficiency as a function of five process variables. Two optimization procedures were carried out to increase the efficiency of encapsulation, with and without constraints referring to the required mean particle size. Correlation was found between the latter and the achievable maximal encapsulation efficiency under optimal process conditions.