Core-Shell PLGA Nanoparticles: In Vitro Evaluation of System Integrity

The objective of this study was to compare the properties of core-shell nanoparticles with a PLGA core and shells composed of different types of polymers, focusing on their structural integrity. The core PLGA nanoparticles were prepared either through a high-pressure homogenization-solvent evaporation technique or nanoprecipitation, using poloxamer 188 (P188), a copolymer of divinyl ether with maleic anhydride (DIVEMA), and human serum albumin (HSA) as the shell-forming polymers. The shells were formed through adsorption, interfacial embedding, or conjugation. For dual fluorescent labeling, the core- and shell-forming polymers were conjugated with Cyanine5, Cyanine3, and rhodamine B. The nanoparticles had negative zeta potentials and sizes ranging from 100 to 250 nm (measured using DLS) depending on the shell structure and preparation technique. The core-shell structure was confirmed using TEM and fluorescence spectroscopy, with the appearance of FRET phenomena due to the donor-acceptor properties of the labels. All of the shells enhanced the cellular uptake of the nanoparticles in Gl261 murine glioma cells. The integrity of the core-shell structures upon their incubation with the cells was evidenced by intracellular colocalization of the fluorescent labels according to the Manders' colocalization coefficients. This comprehensive approach may be useful for the selection of the optimal preparation method even at the early stages of the core-shell nanoparticle development.