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

Abstract 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 ∼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.