Enhanced Antibacterial Activity of Indocyanine Green-Loaded Graphene Oxide via Synergistic Contact Killing, Photothermal and Photodynamic Therapy

Methicillin-resistant Staphylococcus aureus (MRSA) has become a serious threat to human's health. Recently, photodynamic/photothermal therapy (PDT/PTT) has emerged as promising strategies against antibiotics-resistant pathogens due to their broad antibacterial spectrum and negligible resistance. In this work, the photosensitizer indocyanine green (ICG) was loaded on graphene oxide (GO) nanosheets with good encapsulation efficiency high to 92.31%. Under near-infrared (NIR) irradiation, the anti-MRSA efficiency of GO (20 μg/ml), ICG (5 μg/ml) and ICG-GO (5 μg/ml-20 μg/ml) was 33.76%, 40.15% and 99.86%, respectively. We further showed that NIR irradiation mildly increased the temperature to 43.1 °C for ICG-GO, and lead to the highest reactive oxygen species (ROS) generation (316.51% and 157.11% compared to ICG alone and GO alone). In conclusion, ICG-GO has a great potential for antibacterial treatment due to its synergistic contact killing, photothermal and photodynamic activity.