CYTOTOXIC EFFECTS MEDIATED BY PHOTODYNAMIC AND PHOTOTHERMAL THERAPIES COMBINED USING GRAPHENE OXIDE NANOSHEETS AS A CARRIER OF METHYLENE BLUE ON TREATMENT OF HUMAN BREAST CANCER IN VITRO

Photodynamic therapy (PDT) and photothermal (PTT) have emerged as alternatives to conventional therapeutic methods for the treatment of human breast carcinoma. PDT involves: a photosensitizer agent (PS), light with specific wavelength and oxygen. The products of these reactions are reactive oxygen species (ROS) capable of inducing toxic effects to cells and target tissues. In the PTT, one photothermal agent absorbs light. This induces a local increase on temperature causing cell damage, denaturation of proteins and DNA, as well as, tissue coagulation. The methylene blue (MB) is a photosensitizer with absorption in the therapeutic window of 600-900 nm and high photodynamic efficiency. Graphene has been proposed with a good material for drugs loading and delivery. Also it has high efficiency and photothermal absorption at 808 nm. The combination of MB and graphene oxide results in a synergistic device where the photosensitizer and photothermal agents are in a single nanostructure. In this work, the graphene oxide nanosheets (NanoGO) were produced from the carboxylation reaction of graphene oxide. After the reaction, both the Pluronic F127 surfactant and MB were adsorved on the surface of the graphene oxide nanosheets. The NanoGO-MB showed an average hydrodynamic size of 110 nm, a polydispersity index of 0.3 and zeta potential of -46.2 mV. The ultrastructure of NanoGO-MB, in characteristic leaf format, could be observed in transmission electron microscopy. LED (660 nm) and laser (808 nm) devices were manufactured for irradiation of the nanosheets. After irradiation the NanoGO-MB with LED 660 nm, could be observed the production of ROS in a spectrophotometer. During NanoGO-MB irradiation with 808 nm laser (energy density of 20 W/cm2) for 3 minutes, the samples reaching temperature range from 26.7 °C to 51.0 °C showed by thermic camera. This shows the potential of NanoGO-MB in producing irreversible cell damage in cancer cells.