Plasmonic-Fluorescent Janus Ag/Ag2S Nanoparticles for In Situ H2O2-Activated NIR-II Fluorescence Imaging

Silver sulfide (Ag2S) has gained widespread attention in second near-infrared (950-1700 nm, NIR-II) window imaging because of its high fluorescence quantum yield and low toxicity. However, its always on fluorescence shows inapplicability for targeted molecule-activated biomedical applications. Herein, we first developed a novel silver/silver sulfide Janus nanoparticle (Ag/Ag2S JNP) for specific N activatable fluorescence imaging in the NIR-II window. Inner-particle electron compensation from Ag to Ag2S upon laser irradiation endowed JNPs an off state of fluorescence, whereas the oxidization of Ag incubated with H2O2, decreasing the electron-transfer effect and illuminating the NIR-II fluorescence of the Ag2S part. In contrast, the absorption of Ag/Ag2S JNPs slightly decreased in an H2O2-dependent manner, showing an activated photoacoustic imaging mechanism. The Ag/Ag2S JNPs were used for noninvasive location and diagnosis of diseases in vivo, such as for liver injury and cancer, with high sensitivity and accuracy.

Automated summary

Novel silver/silver sulfide Janus nanoparticles (Ag/Ag2S JNPs) have been developed for specific N-activatable fluorescence imaging in the NIR-II window, showing high sensitivity and accuracy in noninvasive disease location and diagnosis, such as liver injury and cancer. The JNPs exhibit an off state of fluorescence with inner-particle electron compensation from Ag to Ag2S upon laser irradiation, and an activated photoacoustic imaging mechanism with slight absorption decrease in an H2O2-dependent manner.