具有红色上转换发光和近红外二区发光的生物可降解镧系掺杂无机纳米颗粒用于生物成像和光动力治疗

The near-infrared-II (NIR-II) lanthanide-doped inorganic nanoparticles (NPs) have received considerable attention because of their low photon scattering and autofluorescence for deep tissue penetration. These NIR-II NPs have a “rigid” and physiologically inert crystal lattice (such as NaYF4:Yb,Er) and cannot be degraded in vivo, limiting their biomedical applications. Changing the chemical structure to achieve the transition from “rigid” to “soft” crystals is a feasible method for realizing their biodegradable applications. Herein, we developed a type of biodegradable NIR-IIb lanthanide-doped inorganic NPs, Na3ZrF7:Yb,Er,Ce (NZF). By optimizing the regulation of Na and doping with Ce3+, the NIR-IIb down-conversion luminescence (DCL) intensity of NZF NPs increased 37 times compared with Na3ZrF7:Yb,Er. Additionally, because of their “soft” crystal lattice features, water can destroy their crystal structure, and the degradation products can be excreted from the organs and tissues. Furthermore, NZF NPs exhibit red-emitting up-conversion luminescence (UCL). After surface modifications, we performed the proof of concept in biodegradable bioimaging applications and photodynamic therapy based on their NIR-IIb DCL and red-emitting UCL. These findings will benefit the future biomedical applications of lanthanide-doped inorganic NPs.