Rapid antibacterial effect of sunlight-exposed silicon nanowire arrays modified with Au/Ag alloy nanoparticles

The continuing emergence of antibiotic-resistant bacteria due to the excessive use of antibiotics has produced a strong demand for novel strategies and new materials that do not lead to bacterial resistance. In the present work silicon nanowire arrays modified with gold-silver alloy nanoparticles (SN-Au/Ag) was investigated as a photo-induced antibacterial material. It was shown that SN-Au/Ag can kill bacteria with high efficiency under sunlight in times of the order of a few minutes, and this is achieved through synergism between photothermal and photocatalytic effects. It appears that the combined effect of heat and reactive oxygen species (ROS) causes bacteria killing through damage to the cell membrane and leakage of cytoplasm contents. Both gold and silver in the alloy nanoparticles are required for the observed bactericidal action. Moreover, the SN-Au/Ag material can be "recycled" without loss of bactericidal activity. It is concluded that the silicon nanowire arrays modified with gold-silver alloy nanoparticles developed in this work has promise as an antibacterial nanomaterial for the development of novel antibiotics.