Because of the biocompatible and biodegradable properties of poly (lactic-co-glycolic
acid) (PLGA), nanoparticles (NPs) based on this polymer have been widely studied for
drug/biomolecule delivery and long-term sustained-release. In this work, two different
formulation methods for lysozyme-loaded PLGA NPs have been developed and optimized
based on the double-emulsion (water/oil/water, W/O/W) solvent evaporation technique.
They differ mainly in the phase in which the surfactant (Pluronic® F68) is added:
water (W-F68) and oil (O-F68). The colloidal properties of these systems (morphology
by SEM and STEM, hydrodynamic size by DLS and NTA, electrophoretic mobility, temporal
stability in different media, protein encapsulation, release, and bioactivity) have
been analyzed. The interaction surfactant-protein depending on the formulation procedure
has been characterized by surface tension and dilatational rheology. Finally, cellular
uptake by human mesenchymal stromal cells and cytotoxicity for both systems have been
analyzed. Spherical hard NPs are made by the two methods However, in one case, they
are monodisperse with diameters of around 120nm (O-F68), and in the other case, a
polydisperse system of NPs with diameters between 100 and 500nm is found (W-F68).
Protein encapsulation efficiency, release and bioactivity are maintained better by
the W-F68 formulation method. This multimodal system is found to be a promising "dual
delivery" system for encapsulating hydrophilic proteins with strong biological activity
at the cell-surface and cytoplasmic levels.