Fluorescent-Labeled Poly(ε-caprolactone) Lipid-Core Nanocapsules: Synthesis, Physicochemical Properties and Macrophage Uptake

Nanoencapsulation has been widely investigated to target drugs to macrophages. Recently, a new class of polymeric nanoparticles, the polysorbate 80-coated lipid-core nanocapsules (LNC), has been proposed as an innovative formulation to easy control the kinetic release of drugs and to target drugs to brain, liver, kidney, solid tumors and inflamed tissues. Our objective was to evaluate the capacity of LNC uptake by macrophage using fluorescent-labeled polymer and multiphoton fluorescence microscopy. Rhodamine B was covalently bound to the polymer, which was used to prepare LNC formulation. Spectroscopic and chromatographic analyses confirmed the macromolecular structure and purity of the new material. The nanoparticle diameters and polydispersity, determined by laser diffraction, dynamic light scattering and nanoparticle tracking analysis, were not significantly altered by the presence of the dye-labeled polymer compared to the non-fluorescent LNC. Fluorimetry study corroborated previous results indicating that the polymer is located at the particlewater interface. Finally, the use of PCL-RB in LNC permitted the observation of the macrophage uptake of those nanoparticles by the red fluorescence inside the cells in subcellular compartments. As a perspective, polysorbate 80-coated lipid-core nanocapsules can be used as a platform for drug transmembrane transport in the therapy of macrophage-related diseases.