Degradable GO-Nanocomposite hydrogels with synergistic photothermal and antibacterial response

Abstract A method for the fabrication of efficient antibacterial and degradable nanocomposite hydrogels combining photothermal energy conversion and inherent bacteria-killing activity was developed by integrating graphene oxide (GO) sheets into a quaternary ammonium salt (QAS) based hydrogel matrix. The dispersion of GO additives was found to enhance the mechanical strength, toughness, and recovery behavior of hydrogels while cleavable ester-groups enabled the rapid degradation of the nanocomposite hydrogels in mild alkali conditions (pH = 8). Nanocomposite hydrogels revealed strong NIR absorption at 808 nm and demonstrated efficient photothermal energy absorption. In the absence of NIR irradiation, nanocomposite hydrogels exhibited a bacterial-killing efficacy of approximately 90% towards E. coli due to the combined action of GO nanosheets and the QAS. NIR irradiation further increased the bacteria-killing efficiency of the nanocomposite hydrogels to near quantitative values (∼99.90%) towards E. coli and S. aureus, thus demonstrating the synergistic bacterial-killing action of photothermal energy conversion, QAS and GO fillers. The inherent bacteria-killing effect of the GO and QAS functionalities combined with the strong increase of antibacterial action via photothermal heating in the ‘optical window’ of biological tissue could render the presented nanocomposite hydrogel interesting for biomedical and antifouling applications.