Near infrared light-mediated enhancement of reactive oxygen species generation through electron transfer from...

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-FeO_xH) was developed for light-activated nanomaterial-mediated PDT. This nanocomposite, GO-FeO_xH was prepared via the one-step electrooxidation of iron nails in an aqueous GO solution. The as-prepared GO-FeO_xH 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 FeO_xH was systematically investigated. We observed that NIR light irradiation promotes electron transfer from GO to the Fe(iii) of FeO_xH and accelerates their reaction with O₂, forming superoxide anion radicals, which then undergo a disproportionation reaction to produce H₂O₂. H₂O₂ then reacts with Fe(ii) in FeO_xH to mediate Fenton reactions, producing amplified hydroxyl radicals. Using in vitro studies, we demonstrated that GO-FeO_xH can be used as a NIR activatable PDT nanoagent, providing efficient cancer therapy.