Physiologically Stable Hydrophilic C60 Nanoparticles for Photodynamic Therapy

摘要： Hydrophilic C60 nanoparticles that are highly stable in living systems were prepared with sugammadex, an anionic γ-cyclodextrin derivative, via a simple procedure for use in biological applications. The prepared C60/sugammadex nanoparticles showed outstanding stability under physiological conditions and even in much harsher conditions. The sugammadex interacted with C60 nanoparticles through strong host-guest interactions on the particle surface, producing a negatively charged layer on the surface of nanoparticles, which contributed to the high stability of the nanoparticles. In addition, the nanoparticles were highly stable in the presence of singly charged cations which are present in abundance in living systems. The stable C60/sugammadex nanoparticles showed a significantly different biological behavior compared to less stable C60 nanoparticles after intravenous administration. Most of the C60 particles accumulated and remained in organs of the reticuloendothelial system (RES) after administration, which are susceptible to forming aggregates in physiological conditions. On the other hand, the C60/sugammadex nanoparticles showed a completely different biological behavior, i.e. longer blood circulation, low RES uptake and elimination with time from organs. The photodynamic activity of C60/sugammadex nanoparticles was evaluated both in vitro and in vivo, and an outstanding antitumor effect was achieved based on the generation of reactive oxygen species under light irradiation. We envision that such stable C60 nanoparticles would be a desirable approach for extending the biological applications of these materials and the precise evaluation of C60 activity in living systems.