ROS Turn Nanoparticle Fluorescence on for Imaging Staphylococcus aureus Infection In Vivo

Abstract Direct, noninvasive, and real‐time imaging of Staphylococcus aureus ( S. aureus ) infection is of great value for quick diagnosis of related disease in clinic, but remains challenging. Herein, employing a rationally designed near‐infrared fluorescence probe Cys(StB u)‐EDA‐Thioketal‐Lys(Cy5.5)‐CBT (TK‐CBT) and a CBT‐Cys click reaction, the fluorescence‐quenched nanoparticles TK‐CBT‐NPs are facilely prepared. Upon oxidation by the abundant reactive oxygen species in S. aureus ‐infected macrophages, TK‐CBT‐NPs are fractured, turning the fluorescence “on” for imaging infections in vitro and in vivo. Specifically, TK‐CBT‐NPs show a 6.1‐fold fluorescence imaging signal enhancement of the macrophages that are infected by S. aureus for 20 h in vitro. At 4 h postinjection, TK‐CBT‐NPs show a 2.8‐fold fluorescence imaging signal enhancement of the sites in mice that are infected by S. aureus for 24 h. It is anticipated that TK‐CBT‐NPs could be applied for diagnosis of S. aureus infections in clinic in the near future.