Extraction of PLGA-microencapsulated proteins using a two-immiscible liquid phases system containing surfactants

The extraction of proteins from PLGA/PLA microspheres by a two-immiscible liquid phases system with the addition of surfactants was investigated.

First, the extraction without surfactants and the interaction between proteins (IFN-α2b and EGF) and empty microspheres (PLGA or PLA) was studied. Next, proteins stability in presence of different surfactants was evaluated by: (1) bicinchoninic acid protein assay, (2) reversed phase-high performance liquid chromatography, and (3) enzyme-linked immunosorbent assay. Then, proteins were extracted with PBS/dichloromethane including selected surfactants and characterized by the above mentioned techniques, biological activity tests, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrospray ionization mass spectrometry.

Without surfactants, protein recovery was only 27-43% for IFN-α2b and 58-73% for EGF. Protein content in solutions incubated with blank microspheres decreased to 66% for IFN-α2b and 86% for EGF. It was only possible to quantify the EGF and IFN-α2b in the same manner as in PBS alone when the surfactant added was Pluronic F-68 and SDS, respectively. Addition of these surfactants allowed the complete isolation of both biomolecules from the microspheres. The extraction procedure did not affect the encapsulated proteins.

Proteins can be quantitatively extracted, without changes, from PLGA/PLA microspheres using PBS/dichloromethane system that include an appropriate surfactant.