Graphene in Mice: Ultrahigh In Vivo Tumor Uptake and Efficient Photothermal Therapy

TLDR

Graphene has been rarely explored in biomedicine compared to extensively studied carbon nanotubes. The study investigates the in vivo behavior of PEGylated nanographene sheets and their potential for efficient photothermal cancer therapy via intravenous administration. PEGylated nanographene sheets were tracked by fluorescence labeling and used for NIR photothermal therapy, achieving tumor ablation after intravenous injection and low‑power laser irradiation. PEGylated nanographene sheets show high tumor uptake, efficient passive targeting, low reticuloendothelial retention, and achieve ultra‑efficient tumor ablation with no observable toxicity in mice.

Abstract

Although biomedical applications of carbon nanotubes have been intensively studied in recent years, its sister, graphene, has been rarely explored in biomedicine. In this work, for the first time we study the in vivo behaviors of nanographene sheets (NGS) with polyethylene glycol (PEG) coating by a fluorescent labeling method. In vivo fluorescence imaging reveals surprisingly high tumor uptake of NGS in several xenograft tumor mouse models. Distinctive from PEGylated carbon nanotubes, PEGylated NGS shows several interesting in vivo behaviors including highly efficient tumor passive targeting and relatively low retention in reticuloendothelial systems. We then utilize the strong optical absorbance of NGS in the near-infrared (NIR) region for in vivo photothermal therapy, achieving ultraefficient tumor ablation after intravenous administration of NGS and low-power NIR laser irradiation on the tumor. Furthermore, no obvious side effect of PEGylated NGS is noted for the injected mice by histology, blood chemistry, and complete blood panel analysis in our pilot toxicity study. Although a lot more efforts are required to further understand the in vivo behaviors and the long-term toxicology of this new type of nanomaterials, our work is the first success of using carbon nanomaterials for efficient in vivo photothermal therapy by intravenous administration and suggests the great promise of graphene in biomedical applications, such as cancer treatment.