Plasmonic-Fluorescent Janus Ag/Ag<sub>2</sub>S Nanoparticles for <i>In Situ</i> H<sub>2</sub>O<sub>2</sub>-Activated NIR-II Fluorescence Imaging
Xuan Zhang, Wenli Wang, Lichao Su, Xiaoguang Ge, Jiamin Ye, Caiyan Zhao, Yu He, Huanghao Yang, Jibin Song, Hongwei Duan
Abstract
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 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.