Photothermal bactericidal surfaces: killing bacteria using light instead of biocides.

Endowing the surfaces of synthetic materials with bactericidal activity is a direct and effective way to prevent bacterial colonization and biofilm formation, solving the related serious problems such as contamination, infection and biofouling. Conventional bactericidal surfaces are usually based on biocidal agents such as antibiotics to kill attached bacteria; however, such surfaces have inherent limitations from their respective biocidal agents and most of them become less effective against the so-called "super bacteria" with multidrug-resistance. In recent years, photothermal bactericidal surfaces have become a promising alternative for combating surface-attached bacteria. These surfaces rely on immobilized photothermal agents, which can convert light energy into thermal energy to effectively eliminate bacteria through various hyperthermia effects, showing several advantages including broad-spectrum sterilization ability, no drug resistance and few side effects. In this review, we highlight the recent development of these photothermal bactericidal surfaces, which are categorized into three types according to the photothermal agents. Multi-functional photothermal bactericidal surfaces with either integrated synergistic killing mechanisms or capability to switch function between killing bacteria and releasing bacteria are also introduced. A brief perspective is finally presented on the directions that show promise for the future.