The core–shell NaGdF 4 :Yb,Er@NaGdF 4 :Yb,Nd upconversion nanoparticles (UCNPs) were successfully obtained with the method of co-precipitation, and the water-solubility of UCNPs was improved by the ligand exchange reaction between nitrosyl tetrafluoroborate (NOBF 4 ) and nanoparticles. The IR-783 dye with negative charge and NOBF 4 -UCNPs with positive charge can bind together by electrostatic action to sensitize UCNPs through the energy transfer from IR-783 to UCNPs. However, with the presence of Na 2 S (a commonly used H 2 S donor), a highly selective reaction between H 2 S and IR-783, which destoried the structure of IR-783 and blocked the energy transfer, thus led to the quenching of luminescent intensity. Based on this, a sensing system for determination of H 2 S has been constructed successfully. The linear range of H 2 S detection by this system is 0.5–15 μM, and the detection limit is 34.17 nM. Furthermore, the dye-sensitized core–shell NaGdF 4 :Yb,Er@NaGdF 4 :Yb,Nd upconversion nanoprobe was applied to real sample analysis with satisfactory results.
Bo Ling,Yaguang Wang,Ruo Mi,Di Wang,Hongqi Chen,Xiaohu Li,Ye Zhang,Lun Wang
Graphical NaGdF 4 ,Yb,Er@NaGdF 4 ,Yb,Tm@NaYF 4 core@shell@shell three-layer structure of upconversion nanoparticles coated with Fe−TCPP metal-organic frameworks nanocomposite was designed and constructed for multimodal imaging and synergetic chemodynamic therapy/photodynamic therapy of tumors. Here, NaGdF 4 ,Yb,Er@NaGdF 4 ,Yb,Tm@NaYF 4 core@shell@shell three-layer structure of upconversion nanoparticles (UCNPs) coated with Fe−Tetrakis (4-carboxyphenyl) porphine (TCPP) metal-organic frameworks (Fe-MOFs) nanocomposite (UCNPs@MOFs) was designed and constructed for multimodal imaging and synergetic chemodynamic therapy (CDT)/photodynamic therapy (PDT) of tumors. The UCNPs@MOFs were successfully applied for tumor cells imaging in vitro and in vivo in near-infrared (NIR) region. The doped Gd was used as contrast agent for the magnetic resonance imaging (MRI) of mouse tumors. The luminescence in the UV-vis region was absorbed by the Fe-MOFs to produce singlet oxygen ( 1 O 2 ) for PDT. The Fe 3+ doped in the MOFs can catalyze H 2 O 2 to produce oxygen and hydroxyl radical (⋅OH). Hydroxyl radical is used in CDT and cooperates with the 1 O 2 of PDT. Based on the CDT/PDT synergistic effects, the UCNPs@MOFs nanocomposite had obviously enhanced tumor inhibitory efficiency in vivo. These results described that the asprared UCNPs@MOFs nanocomposite have great potential in the effective multimodal imaging and treatment of tumors.
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