Photothermal therapeutic effect by gold nanostars/extracellular vesicles nanocomplex on melanoma cells.

Photothermal therapy (PTT) is a method for treating cancer using the heat generated by light irradiation, often in combination with light-absorbing materials. Efficient PTT requires a drug delivery system to deliver light-absorbing materials to cancerous tissues. Gold nanostars (GNSs) enable efficient PTT through absorbing long-wavelength light. In this study, we established a platform for preparing GNSs-loaded extracellular vesicles (EVs), that were expected to provide the combined biological functionality of EVs and photothermal conversion properties. By electrostatically binding cationic polyethylene glycol (PEG)-modified GNSs (PEG-GNSs) to naturally negatively charged EVs, EV/PEG-GNSs nanocomplexes (EV-GNSs) were obtained by simply mixing the two components. The prepared EV-GNSs were approximately 200 nm in size and exhibited a negative surface charge. The surface protein marker of EVs, CD63, was detected using western blot, suggesting that the EVs were intact. In vitro evaluation showed that EV-GNSs exhibited better photothermal conversion properties than PEG-GNSs alone. When EV-GNSs were added to the cells, high laser-responsive cytotoxicity was observed following laser irradiation. Thus, EV-GNSs developed in this study may be suitable for PTT using gold-based nanoparticles.