Exchangeability of FITC-SiO₂ Nanoparticles Between Cancer Cells Increases the Range of Drug Delivery

Drug delivery system studies aim to improve nanoparticle (NP) formulation to enable efficient delivery of NPs to tumors. However, NPs must be transported by blood or through direct injection. How NPs leave the circulatory system and how NPs diffuse into a tumor remain unclear, and this uncertainty is a limitation of drug delivery systems. The intimate connection between these questions and metabolism may be related to their biosafety in vivo. Thus, in this study, classical carrier SiO₂ NPs were used as typical transport NPs, and fluorescein isothiocyanate (FITC) was used as the representative drug and tracer. As exosome and tunneling nanotubes (TNTs) are the most relevant mechanism for NP transportation and considering the local situation in a tumor, we focused on identifying this phenomenon and investigating TNTs. In conclusion, we effectively demonstrated that NPs can be transferred from cell to cell. Nanotubes may play an important role in this process.