Multicomponent Organic Nanoparticles for Fluorescence Studies in Biological Systems

Abstract The formation of dual‐component organic nanoparticles by a modified emulsion‐templated freeze‐drying approach leads to aqueous nanosuspensions showing fluorescence (Förster) resonance energy transfer (FRET) from within a distribution of single nanoparticles. The combination of both FRET dyes within dual‐component nanoparticles (<200 nm) allows the spatial and physical monitoring of the particles, as the FRET signal is lost on dissolution and breakdown of the nanoparticles. The monitoring of accumulation by Caco‐2 cells and macrophages shows very limited internalization within the non‐phagocytic cells. Conservation of FRET within the macrophages confirms extensive whole‐particle internalization. The cellular permeability through Caco‐2 monolayers is also assessed and movement of intact dual‐component particles is observed, suggesting a mechanism for enhanced pharmacokinetics in vivo.