Factorial design formulation optimization and in vitro characterization of curcumin-loaded PLGA nanoparticles for colon delivery

We have employed a 2³ factorial design approach for optimizing curcumin-loaded PLGA nanoparticles with a specific interest in colon treatment. Curcumin-loaded PLGA nanoparticles were prepared by using the single emulsion solvent evaporation technique. In vitro characterizations of the curcumin-loaded nanoparticles revealed that the mean particle sizes of the nanoparticles ranged from 181.5 nm to 206.9 nm, the zeta potential values were in the range of -30.6 to -41.7 mV, the encapsulation efficiencies were between 58.1 and 83.2% and the drug release from the formulations was in the range of 34.4-62.8%. The properties of the optimized curcumin-loaded PLGA nanoparticles predicted by the 2³ factorial design approach correlated very well with the experimentally determined particle size of 219.6 nm, zeta potential of -36.8 mV, encapsulation efficiency of 74.4% and a 56.2% cumulative drug release after 24 h. In vitro cellular uptake studies with HT-29 cells showed that the optimized curcumin-loaded PLGA nanoparticle exhibited a much higher cellular uptake of curcumin (i.e. 7.01 ± 0.33 μg/10⁶ cells) than a native curcumin solution (3.74 ± 0.56 μg/10⁶ cells). Stability studies also showed that all investigated formulations were stable at least for 2 months.