Mitochondrial specific photodynamic therapy by rare-earth nanoparticles mediated near-infrared graphene quantum dots

Photodynamic therapy (PDT) has been proposed in cancer treatment for decades, but its clinical translation is significantly impeded by the low yield of ROS, poor tissue penetration depth of most current photosensitizers, and short lifetime of ROS. These limitations directly affect the therapeutic effect of PDT in cancer therapy. Here we proposed a new strategy by collaboratively integrating rare-earth doped upconversion nanoparticles (UCNP) with graphene quantum dot (GQD) for highly efficacious PDT, based on the merits of UCNP, which can emit UV-vis light under near-infrared light (NIR) excitation, and GQD, which can produce 1O2 efficiently. For GQD-decorated UCNP nanoparticles (UCNP-GQD), the emission light from UCNP can further excite GQD with prominent 1O2 generation for NIR-triggered PDT. Furthermore, a hydrophilic rhodamine derivative, TRITC, is covalently tethered to afford the resultant UCNP-GQD/TRITC, possessing distinct mitochondrial targeting property. Thus mitochondrial specific PDT with in-situ1O2 burst in mitochondria induces sharp decrease of mitochondrial membrane potential, which initiates the tumor cell apoptosis irreversibly. Importantly, in vivo experiments demonstrate the tumor inhibition of mitochondrial targeting UCNP-GQD/TRITC with improved therapeutic efficiency compared with non-targeting UCNP-GQD. The proposed strategy highlights the advantages of precision organelles-specific PDT in cancer therapy.