Nanocomposites of Nitrogen-Doped Graphene Oxide and Manganese Oxide for Photodynamic Therapy and Magnetic Resonance Imaging.

Cancer is a leading cause of death worldwide. Conventional methods of cancer treatment, including chemotherapy and radiotherapy, are associated with multiple side effects. Recently, photodynamic therapy (PDT) has emerged as an effective therapeutic modality for cancer treatment without adversely affecting normal tissue. In this study, we synthesized nitrogen doped graphene (NDG) and conjugated it with MnO nanoparticles to produce NDG-MnO nanocomposite with the aim of testing its bimodal performance including PDT and magnetic resonance imaging (MRI). We did not use any linker or binder for conjugation between NDG and MnO, rather they were anchored by a milling process. The results of cell viability analysis showed that NDG-MnO nanocomposites caused significant cell death under laser irradiation, while control and MnO nanoparticles showed negligible cell death. We observed increased generation of singlet oxygen after exposure of NDG-MnO nanocomposites, which was directly proportional to the duration of laser irradiation. The results of MRI showed concentration dependent enhancement of signal intensity with an increasing concentration of NDG-MnO nanocomposites. In conclusion, NDG-MnO nanocomposites did not cause any cytotoxicity under physiological conditions. However, they produced significant and dose-dependent cytotoxicity in cancer cells after laser irradiation. NDG-MnO nanocomposites also exhibited concentration-dependent MRI contrast property, suggesting their possible application for cancer imaging. Further studies are warranted to test the theranostic potential of NDG-MnO nanocomposites using animal models of cancer.