Antibacterial Properties of Curcumin Loaded Graphene Oxide Flakes

Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for serious hospital infections worldwide and represents a global public health problem. Curcumin, the major constituent of turmeric, is effective against MRSA but at high and cytotoxic concentrations or in combination with antibiotics. The major issue in curcumin-based therapies is the poor solubility of this hydrophobic compound and its cytotoxicity at high doses. In this work, we describe the efficacy of GOCU, a composite made of curcumin and Graphene Oxide (GO) in the MRSA infections treatment. GO is a nanomaterial with a large surface area and high drug loading capacity. GO has also antibacterial properties due mainly to a mechanical cutting of the bacterial membranes. We investigated GOCU properties by means of Dynamic Light Scattering, Electron and Atomic Force Microscopy and Zeta Potential. We analysed growth curves and Minimal Inhibitory and Bactericidal concentrations (MIC and MBC), and cytotoxic effects on cells by MTT assay. We report the capacity of GO to support and stabilize curcumin molecules in water environment. Curcumin creates a corona around Graphene Oxide sheets and modifies surface charge towards more positive values. We demonstrate the efficacy of GOCU against MRSA at concentration down to 2m g/ml, while GO alone is effective only at concentrations higher than 100m g/ml. However, GOCU displays low toxicity on fibroblasts cells in respect to bare GO. The low MIC of GOCU against MRSA and absence of cytotoxicity open new applications of GOCU nanomaterial in the global health challenge of the antibiotic resistant infections treatment.