A graphene quantum dot photodynamic therapy agent with high singlet oxygen generation

TLDR

Photodynamic therapy is limited by low singlet‑oxygen quantum yields, photobleaching, and poor biocompatibility, while photosensitisers generate reactive oxygen species to treat cancer. The authors aim to develop a graphene quantum dot photosensitiser that achieves the highest reported singlet‑oxygen quantum yield (~1.3) and offers superior water dispersibility, photostability, pH stability, and biocompatibility for next‑generation carbon‑based PDT agents. GQDs generate singlet oxygen through a multistate sensitization process, enabling simultaneous imaging and highly efficient cancer therapy as demonstrated in vitro and in vivo. The GQDs exhibit a broad UV–visible absorption, strong deep‑red emission, a singlet‑oxygen quantum yield of ~1.3, and effective imaging and therapeutic performance in cell and animal studies.

Abstract

Clinical applications of current photodynamic therapy (PDT) agents are often limited by their low singlet oxygen (1O2) quantum yields, as well as by photobleaching and poor biocompatibility. Here we present a new PDT agent based on graphene quantum dots (GQDs) that can produce 1O2 via a multistate sensitization process, resulting in a quantum yield of ~1.3, the highest reported for PDT agents. The GQDs also exhibit a broad absorption band spanning the UV region and the entire visible region and a strong deep-red emission. Through in vitro and in vivo studies, we demonstrate that GQDs can be used as PDT agents, simultaneously allowing imaging and providing a highly efficient cancer therapy. The present work may lead to a new generation of carbon-based nanomaterial PDT agents with overall performance superior to conventional agents in terms of 1O2 quantum yield, water dispersibility, photo- and pH-stability, and biocompatibility. Photosensitisers are used in cancer therapy to promote the formation of reactive oxygen species on irradiation with light. Here, the authors present a graphene quantum dot photosensitiser with a singlet oxygen quantum yield of approximately 1.3, and investigate its in vitro and in vivoapplications