Solvatochromic fluorescent BODIPY derivative as imaging agent in camptothecin loaded hexosomes for possible theranostic applications

We here discuss the potential theranostic nanomedicine application of an innovative formulation consisting of monoolein-based nanoparticles with a two-dimensional hexagonal inner structure stabilized in water using a mixture of PEO132–PPO50–PEO132 block copolymers with and without conjugated folate for targeting. The proposed tumor-cell targeted formulation was shown to be able to simultaneously host the model anticancer drug camptothecin and a pyrene-modified BODIPY fluorophore, based on dynamic light scattering, small-angle X-ray scattering, and cryogenic transmission electron microscopy. The photophysical properties of the fluorophore were studied in solution in various solvents. A marked fluorescent solvatochromism, whose origin was explained by time-dependent density functional theory theoretical calculations, was observed. Fluorescence microscopy showed that HeLa cells readily internalize these nanoparticles, and that the fluorophore localizes within the lipid droplets. In addition, cytotoxicity test revealed that these nanoparticles are not toxic at the concentration used for the imaging analysis.