Indocyanine Green Loaded Polymeric Nanoparticles: Physicochemical Characterization and Interaction Studies with Caco-2 Cell Line by Light and Transmission Electron Microscopy

Biomedical applications of nanoparticles (NPs) have reached an increasing development in recent years. Recently, we demonstrated that newly synthesized poly (ethyl 2-cyanoacrylate) nanoparticles (PECA-NPs) are possible antitumor agents due to their cytotoxicity for cancer cells. Indocyanine green (ICG), an amphiphilic tricarbocyanine fluorescent dye, is widely used for the detection of tumoral extension in different organs during clinical surgery. Moreover, this fluorescent agent is unstable and it has a rapid clearance in physiological conditions in vivo. In this study, ICG was charged in PECA-NPs to improve its aqueous stability and make easier its use for the identification of tumor cells. Microscopic and ultrastructural aspects concerning the related in vitro interactions between ICG-loaded NPs and tumor cell culture were investigated. Obtained results showed an effective stabilization of ICG; furthermore, color inclusions inside the cells treated with ICG-loaded NPs demonstrated the internalization of NPs with associated ICG. Transmission electron microscopy (TEM) analysis demonstrated the cytoplasmic presence of coated vesicles (Ø ≤ 100 nm), hypothesizing their involvement in the mechanism of endocytosis. Therefore, ICG-loaded NPs could be proposed as agents for tumor diagnosis, hypothesizing also in the future a specific therapeutic treatment.