Concise nanotherapeutic modality for cancer involving graphene oxide dots in conjunction with ascorbic acid

Abstract

Cancer cells tend to have higher intracellular reactive oxygen species (ROS) levels and are more vulnerable to ROS-generating therapies such as ascorbic acid (H₂Asc) therapy, whose potency has been explored by several clinical trials. However, its efficiency is restricted by the requirement of pharmacologically high local H₂Asc concentrations. Here, we show that nitrogen-doped graphene oxide dots (NGODs), which are highly crystalline and biocompatible, can serve as a catalytic medium for improving H₂Asc cancer therapy at orally achievable physiological H₂Asc concentrations. NGODs catalyze H₂Asc oxidation for H₂O₂ and dehydroascorbic acid generation to disrupt cancer cells by consuming intracellular glutathione (GSH) and inducing ROS damage. This is the first study to demonstrate the direct consumption of GSH using a carbon-based nano-catalyst (NGODs), which further expedites tumor killing. In addition, as in our previous study, NGODs can also serve as a highly efficient photosensitizer for photodynamic therapy. Under illumination, NGODs produce a considerable amount of H₂O₂ in the presence of physiological levels of H₂Asc as a hole scavenger and further enhance the therapeutic efficiency. Thus, a concise nanotherapeutic modality could be achieved through the conjunction of multifunctional NGODs and H₂Asc to selectively eliminate deep-seated and superficial tumors simultaneously (under 65% of normal cell viability, it kills almost all cancer cells). Note that this level of therapeutic versatility generally requires multiple components and complex manufacturing processes that run into difficulties with FDA regulations and clinical applications. In this study, the concise NGOD–H₂Asc nanotherapeutic modality has demonstrated its great potential in cancer therapy.