Synthesis of NIR-II Fluorescent Hybrid Ag2S/ZnPc Nanoparticles for in vitro Photodynamic Therapy

Fluorescence imaging-guided photodynamic therapy (PDT), particularly near infrared II (NIR-II) fluorescence featuring deep penetration depth, can greatly improve the treatment outcomes with precise administration. In this work, a reprecipitation-encapsulation method was used to co-load NIR-II fluorescent Ag2S quantum dots (QDs) and photosensitizer zinc phthalocyanine (ZnPc) into single nanoparticles (NPs), i. e., Ag2S/ZnPc NPs. Moreover, the resultant NPs were coated by a poly-L-lysine (PLL) layer, which endowed the initial hydrophobic Ag2S QDs and ZnPc with good biocompatibility. Ag2S/ZnPc NPs exhibited a hydrodynamic diameter of similar to 70 nm, strong NIR-II fluorescence peaking at 1052 nm, efficient cellular uptaken, and high singlet oxygen generation. Taking advantage of Ag2S/ZnPc NPs, efficient phototherapeutic efficacy was achieved on HeLa cells upon the irradiation of 660 nm light, and a deep optical tissue penetration depth of 1.4 mm was obtained under 808 nm excitation. These results suggested that the facilely prepared Ag2S/ZnPc NPs are very promising for NIR-II fluorescence imaging-guided in vivo PDT.