In vivo tumor accumulation of nanoparticles formed by ionic interaction of glycol chitosan and fatty acid ethyl ester.

In this study, novel fatty acid ethyl ester (FAEE)-based glycol chitosan (GC) nanoparticles were prepared through an electrostatic interaction. Additionally, the tumor accumulation of the FAEE-GC nanoparticles was evaluated in order to determine the enhanced permeability and retention (EPR) effect in a breast tumor model. FAEE, including eicosapentaenoic acid ethyl ester (EPAEE) and docosahexanoic acid ethyl ester (DHAEE), successfully formed ionic complexes with GC. The FAEE-GC complexes were self-aggregated with a spherical shape and a mean diameter of 110-333 nm in aqueous media. Cy7 was labeled to the FAEE-GC complexes for the in vivo optical imaging. A tumor animal model was developed by inoculating MDA-MB231 breast tumor cells into the right flanks of mice. The Cy7-labeled FAEE-GC nanoparticles were injected into the tail vein of the tumor-bearing mice. Fluorescence signals were strongly observed in the tumor because of the EPR effect. In the ex vivo imaging of the mice, the highest fluorescence intensity, except for the kidney, was observed in the tumor. Therefore, the FAEE-GC nanoparticles could be a useful vehicle for FAEE formulation as well as an in vivo tumor-selective drug delivery carrier.