Determination of antibacterial and photothermal properties of novel composites based on graphene oxide/reduced graphene oxide, gold nanoparticles, and graphene quantum dots

Pathogenic bacteria have emerged as a worldwide health problem nowadays as a result of excessive use or misuse of antibiotics. Thus the prevention of bacteria-mediated infections through the development of novel antibacterial materials has received significant importance. Here, we combined graphene-based materials, namely graphene oxide (GO) and reduced graphene oxide (rGO), with gold nanoparticles and modified graphene quantum dots to obtain improved composite materials. Also, we measured their light-to-heat conversion under an 808 nm laser illumination and their ability to generate singlet oxygen under photoexcitation. We determined their antibacterial properties against 8 bacterial strains. The composite of rGO showed slightly improved photothermal conversion compared to the GO counterpart due to its larger sp2 domains, while the GO composite showed the highest capacity to generate 1O2 under blue-light photoexcitation. All prepared composites had the minimum inhibitory concentrations in the range of 125 μg mL−1 to 500 μg mL−1 and did not show any cytotoxicity against MRC-5 cells.