A novel multifunctional theranostic nanoplatform was fabricated via in situ growth of ultrasmall Ag₂Se nanodots on the surface of chitosan (CS) coated NaYF₄:Yb/[email protected]₄:Nd/[email protected]₄ upconversion nanoparticles (UCNPs). NaYF₄:Yb/[email protected]₄:Nd/[email protected]₄@[email protected]₂Se (labeled as [email protected]@Ag₂Se) nanocomposites can provide downshifting (DS) and upconversion (UC) luminescence in NIR biological window I and II under 808-nm continuous-wave laser excitation simultaneously. Meanwhile, the attached Ag₂Se nanodots could produce hyperthermia and photoacoustic energy upon 808-nm laser irradiation due to its strong near-infrared (NIR) absorbance. Together with the X-ray absorbance feature of lanthanide components, the nanocomposites with excellent luminescent properties, high X-ray attenuation coefficient and strong NIR absorbance could be utilized as a smart contrast agent for upconversion luminescence (UCL)/downshifting luminescence (DSL)/computer tomography (CT)/photoacoustic (PA) multimodal imaging in vitro and in vivo. Furthermore, the as-synthesized nanocomposites possess superior photothermal performance, good biocompatibility, and negligible toxicity, showing great potential as an ideal photothermal therapy (PTT) agent. These outstanding properties revealed that [email protected]@Ag₂Se nanocomposites are promising theranostic agents for tetra-modal imaging-guided PTT of cancer.

通过在壳聚糖（CS）包被的NaYF ₄：Yb / [受电子邮件保护] ₄：Nd / [受电子邮件保护] ₄上转换纳米粒子（UCNPs）上原位生长超小Ag ₂ Se纳米点，制备了一种新型的多功能理论上的纳米平台。NaYF ₄：Yb / [受电子邮件保护] ₄：Nd / [受电子邮件保护] ₄ @ [受电子邮件保护] ₂ Se（标记为[受电子邮件保护] @Ag ₂ Se）纳米复合材料可以提供下移（DS）和上转换（UC）发光在808-nm连续波激光激发下同时在NIR生物窗口I和II中的发射。同时，附上Ag ₂硒纳米点由于其强大的近红外（NIR）吸收能力，在808 nm激光照射下会产生高温和光声能量。结合镧系元素的X射线吸收特性，具有优异的发光性能，高X射线衰减系数和强NIR吸收性的纳米复合材料可以用作上转换发光（UCL）/下移发光（DSL）/体外和体内计算机断层扫描（CT）/光声（PA）多峰成像。此外，合成后的纳米复合材料具有优异的光热性能，良好的生物相容性和可忽略的毒性，显示出作为理想的光热疗法（PTT）剂的巨大潜力。这些突出的特性表明，[电子邮件保护的] @Ag ₂ Se纳米复合材料是有望用于癌症的四峰成像引导PTT的治疗剂。