Design of high payload PLGA nanoparticles containing melittin/sodium dodecyl sulfate complex by the hydrophobic ion-pairing technique

Abstract

The water-soluble peptide, melittin, was modified with an anionic agent, sodium dodecyl sulfate by hydrophobic ion-pairing. Investigations showed that the formed complex was very soluble in organic solvent, especially, in dimethylsulfoxide and dehydrated alcohol. Furthermore, the physiochemical properties of the complex in the solid state or in an aqueous medium were characterized using octanol/water partition measurement, Fourier transform infrared spectroscopy, and differential scanning calorimetry. The complex was formulated into poly(d,l-lactide–co-glycolide acid) nanoparticles by an emulsion solvent diffusion method. It was found that the nanoparticles of about 130 nm in size can be produced with a high encapsulation efficiency, and the entrapment of nanoparticles prepared with the formed complex increased from about 50% to nearly 100% compared with that for pure melittin. Moreover, the growth inhibitory effects of modified melittin and melittin-loaded nanoparticles in breast cancer MCF-7 cells were not changed comparing with free melittin as determined by (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay.