A core–shell-structured composite by combining mesoporous silica with upconversion luminescence (UCL) property had considerable application potentials in the fields of drug delivery, disease diagnosis, and therapy. In this paper, a monodisperse, core–shell-structured NaYF₄:Yb,Er@nSiO₂@mSiO₂ nanoparticle (UCNP@MSNs-FA) with excellent UCL property was successfully fabricated by a facile two-step sol–gel strategy and by modifying the surface with folic acid (FA) to strengthen its tumor-targeting performance. The properties of the composite were studied extensively, which indicated that UCNP@MSNs-FA possessed good dispersion, typical core–shell-structured with high specific surface area (132.775 m²/g), and excellent UCL property that improve cell imaging and drug delivery. The viability of L929 cells and hemolysis assay demonstrated the good biocompatibility of the composite. By using doxorubicin hydrochloride (DOX) as a model drug, the drug loading content and encapsulation efficiency of UCNP@MSNs-FA could reach as high as 11.2% and 37.3%, respectively, which proved the effectiveness to load anticancer drugs. In addition, the DOX-UCNP@MSNs-FA system exhibited sustained drug release and strong pH-dependent performance, in which the drug release would be accelerated at the slightly acidic microenvironment in the tumor. Moreover, experimental results indicated that DOX-UCNP@MSNs-FA exhibited specific cytotoxicity to KB cells but weakened toxicity to FR-negative cells. Therefore, the as-prepared UCNP@MSNs-FA could be used potential for simultaneous targeted anti-cancer drug delivery and cell imaging and enhance the therapeutic efficacy against FR-positive tumor cells.

结合中孔二氧化硅和上转换发光（UCL）特性的核-壳结构复合材料在药物输送，疾病诊断和治疗领域具有巨大的应用潜力。本文通过简便的两步溶胶-凝胶法成功制备了具有优异的UCL性质的单分散，核壳结构的NaYF ₄：Yb，Er @ n SiO ₂ @ m SiO ₂纳米颗粒（UCNP @ MSNs-FA）。并通过使用叶酸（FA）修饰表面来增强其肿瘤靶向性能。对该复合材料的性能进行了广泛的研究，表明UCNP @ MSNs-FA具有良好的分散性，是典型的核-壳结构结构，具有较高的比表面积（132.775 m ²/ g）和卓越的UCL特性，可改善细胞成像和药物传递。L929细胞的活力和溶血分析表明该复合材料具有良好的生物相容性。以盐酸阿霉素（DOX）为模型药物，UCNP @ MSNs-FA的载药量和包封率可分别达到11.2％和37.3％，证明了抗癌药的装载效果。此外，DOX-UCNP @ MSNs-FA系统表现出持续的药物释放和强的pH依赖性性能，其中在肿瘤的微酸性微环境下药物释放将被加速。此外，实验结果表明，DOX-UCNP @ MSNs-FA对KB细胞表现出特异性的细胞毒性，但对FR阴性细胞的毒性减弱。因此，