Near infrared light-mediated enhancement of reactive oxygen species generation through electron transfer from graphene oxide to iron hydroxide/oxide.

Clinical applications of current photodynamic therapy (PDT) agents are often restricted to be activated only by UV and visible light, which have very poor tissue penetration depths. In this study, a new near infrared (NIR)-absorbing nanoagent based on graphene oxide decorated with iron hydroxide/oxide (GO-FeOx H) was developed for light-activated nanomaterial-mediated PDT. This nanocomposite, GO-FeOx H was prepared via the one-step electrooxidation of iron nails in an aqueous GO solution. The as-prepared GO-FeOx H showed a much higher reactive oxygen species (ROS) activity under NIR light irradiation than GO. Through a variety of spectroscopic analyses, the mechanism involved in the enhancement of ROS activity of GO by FeOx H was systematically investigated. We observed that NIR light irradiation promotes electron transfer from GO to the Fe(iii) of FeOx H and accelerates their reaction with O2 , forming superoxide anion radicals, which then undergo a disproportionation reaction to produce H2 O2 . H2 O2 then reacts with Fe(ii) in FeOx H to mediate Fenton reactions, producing amplified hydroxyl radicals. Using in vitro studies, we demonstrated that GO-FeOx H can be used as a NIR activatable PDT nanoagent, providing efficient cancer therapy.