Fabrication and fluorescence imaging properties of indocyanine green-loaded poly(lactic-co-glycolic acid) nanoparticles

This work proposed a method for fabricating poly(lactic-co-glycolic acid) (PLGA) nanoparticles (ca. 70 nm) loaded with indocyanine green (ICG) molecules by an antisolvent crystallization method using dimethyl sulfoxide (DMSO) as a good solvent and water as a poor solvent. ICG molecules were loaded to PLGA nanoparticles by mixing PLGA, polyethylenimine, and polyethylene glycol (PEG) in DMSO with polyvinyl alcohol, albumin, and ICG in water. The ICG-loaded PLGA nanoparticle colloid solutions emitted fluorescence even at high ICG concentrations. Not only the tissues of a tumor-bearing mouse but also the tumor could be imaged with an IVIS system by injecting ICG-loaded PLGA nanoparticle colloid solution into the tail vein of the mouse and measuring the emitted fluorescence intensity, though some ICG-loaded PLGA nanoparticles were trapped in tissues such as the liver and spleen due to insufficient PEGylation. Thus, this work showed that ICG-loaded PLGA nanoparticles have potential for cancer imaging. Graphical abstract