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Designing the synthesis of inorganic micro/nanocrystals that are hard to get through conventional synthetic routes remains a challenging issue. Herein, we developed a novel in situ topotactic transformation synthetic strategy towards Y2O2S micro/nanocrystals based on high topotactic structural matching with the crystalline relationship between [001]Y4O(OH)9NO3//[001]Y2O2S and [001]LYH//[010]Y2O2S (LYH is Y2(OH)5NO3·nH2O). We have contrastively elucidated the in situ topotactic transformation mechanism from the crystal structure point of view and found that the microscopically topotactic structural matching in structural anisotropy and atomic arrangement facilitates the Y4O(OH)9NO3 → Y2O2S and LYH → Y2O2S transformation processes, respectively. Interestingly, the morphology contours were maintained well although a high degree of crystal lattice rearrangement was involved during the topotactic transformation process, which contributed to two brand-new morphologies that were unavailable by the conventional synthetic route (hexagonal microprism and quadrangle nanoplate) for Y2O2S. Besides, we also selected amorphous Y(OH)CO3 sub-microsphere as a precursor to comparatively study the structural topotactic transformation. Furthermore, the luminescence properties of the as-prepared micro/nanophosphors were emphasized by featuring the multicolor emissions by downshifting (Eu3+, Tb3+) and upconversion (Yb3+/Er3+, Yb3+/Tm3+) luminescence. Our study may bring a new direction of thought for the targeted synthesis of inorganic micro/nanocrystals that are difficult to get via conventional synthetic routes. [ABSTRACT FROM AUTHOR]

Non‐invasive theranostics that integrate the advantages of multimodality imaging and therapeutics have great potential in the field of biomedicine. Herein, a new nanohybrid based on Bi2Se3‐conjugated upconversion nanoparticles (UCNPs) has been successfully developed through a simple in situ growth strategy. Under 808 nm near‐infrared laser irradiation, the UCNPs can emit bright visible light, whereas the Bi2Se3 nanomaterial exhibits efficient photothermal conversion capacity. Moreover, the as‐synthesized UCNP–Bi2Se3 nanohybrid exhibits efficient cell upconversion luminescence (UCL), reasonable CT imaging, and admirable cancer cell ablation capacity, further emphasizing the efficiency of this strategy for simultaneous UCL imaging and photothermal therapy. The designed theranostic strategy guided by dual‐modal imaging endowed with real‐time dynamic monitoring, remote controllability, and non‐invasiveness makes the UCNP–Bi2Se3 nanohybrid an ideal candidate for non‐invasive multimodal imaging‐guided photothermal therapy for the precise diagnosis and treatment of cancer. [ABSTRACT FROM AUTHOR]

Design and synthesis of inorganic micro/nanocrystals with target phase/morphology is a focal theme in nanoscience and nanotechnology. Herein, a novel in situ topotactic transformation synthesis strategy, Y4O(OH)9NO3→ Y(OH)2.02F0.98→ YOF towards YOF:Ln3+ (Ln = Eu, Tb, Yb/Er, Yb/Tm) microcrystals has been reported. We have elaborated the in situ topotactic transformation from Y4O(OH)9NO3 to Y(OH)2.02F0.98 based on the topotactic structural matching, where similar anisotropic channel structures along the c-axis and the analogous coordination structure of lanthanide ions were involved. We have also extended this synthesis strategy to the topologically isomorphic Y(OH)3 and β-NaYF4 and found that the fine difference in structural evolution during the transformation processes led to different morphological evolutions for the two. To the best of our knowledge, for the first time, we report such an in situ topotactic transformation with a high degree of crystal lattice rearrangement, where enneagonal channels transformed into hexagonal channels while maintaining the morphology contour. Moreover, we have systematically investigated the influences of experimental variables on the morphology, size, and composition of the final products. Furthermore, the luminescence properties of the as-prepared YOF:Ln3+ microcrystals were emphasized by demonstrating the multicolor emissions via downconversion and upconversion luminescence. Our study may provide significant guidance towards the synthesis of inorganic micro/nanocrystals with a target phase structure/morphology on the basis of topotactic structural matching. [ABSTRACT FROM AUTHOR]

Monodisperse YF3 and YOF porous sub-microspheres were synthesized by using a novel sacrificing template method with amorphous Y(OH)CO3 ⋅ x H2O as the precursors and the template. It was found that the size and shape were well maintained, and the condensed precursor was transformed into uniform porous structures after fluoridation. By fine-tuning the feed of the fluorine source, the final product could be converted from YF3 to YOF. A possible growth mechanism is proposed for the uniform porous YF3 structure and the porous yolk-shell-like YOF structure. The luminescence properties showed that the as-synthesized YF3:Ln3+ (Ln=Eu, Tb, Ce, Ce/Tb, Yb/Er, Yb/Ho, and Yb/Tm) products exhibited strong multicolor emissions, which included down-/upconversion and energy-transfer processes. Additionally, YOX (X=Cl and Br) could be obtained if a different halogen source was used during calcination. However, the spheres were almost completely destroyed. Our novel synthetic route can also be extended to other lanthanide fluorides (REF3, RE=Gd, Lu), which may open a facile way to fabricate novel porous nanostructures. [ABSTRACT FROM AUTHOR]

Non-invasive theranostics that integrate the advantages of multimodality imaging and therapeutics have great potential in the field of biomedicine. Herein, a new nanohybrid based on Bi 2 Se 3 -conjugated upconversion nanoparticles (UCNPs) has been successfully developed through a simple in situ growth strategy. Under 808 nm near-infrared laser irradiation, the UCNPs can emit bright visible light, whereas the Bi 2 Se 3 nanomaterial exhibits efficient photothermal conversion capacity. Moreover, the as-synthesized UCNP-Bi 2 Se 3 nanohybrid exhibits efficient cell upconversion luminescence (UCL), reasonable CT imaging, and admirable cancer cell ablation capacity, further emphasizing the efficiency of this strategy for simultaneous UCL imaging and photothermal therapy. The designed theranostic strategy guided by dual-modal imaging endowed with real-time dynamic monitoring, remote controllability, and non-invasiveness makes the UCNP-Bi 2 Se 3 nanohybrid an ideal candidate for non-invasive multimodal imaging-guided photothermal therapy for the precise diagnosis and treatment of cancer., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The design and synthesis of responsive inorganic nanocapsules have attracted intensive research interest in cancer treatment. The combination of non-invasive diagnosis and chemotherapy into a single theranostic nanoplatform is prospective in the biomedical field. In this work, a polyacrylic acid (PAA)-functionalized porous BiF 3 :Yb,Er nanocarrier was constructed via a straightforward one-pot solvothermal strategy. Compared with the undoped BiF 3 sub-microspheres, the lanthanide ion (Ln 3+ ) doping endowed the BiF 3 material with a smaller size and increased BET specific surface area and pore volume, which make it suitable as a drug carrier. It was found that the synthesized nanomaterial could effectively relieve the side effects of doxorubicin (DOX) and exhibited pH-dependent DOX loading and release. Its satisfactory biocompatibility and efficient tumor inhibition were emphasized by a series of in vitro/in vivo experiments. In addition, the synthesized nanomaterial exhibited favorable CT contrast efficacy due to the excellent X-ray attenuation coefficient of Bi. Moreover, characteristic upconversion luminescence and temperature sensing in a wide temperature range were realized over the synthesized BiF 3 :Yb,Er sample. Therefore, carboxyl-functionalized BiF 3 :Yb,Er can be expected to be an ideal candidate in the fabrication of temperature sensing and multifunctional theranostic nanoplatforms.

Herein, a novel multifunctional nanoplatform was designed toward multimodality imaging and photothermal therapy (PTT). It was found that Bi nanoparticles could grow in situ on the surface of NaYF 4 :20%Yb,2%Er@NaYF 4 :40%Yb@NaGdF 4 core-shell nanoparticles (labeled as UCNPs). In this structure, UCNPs were mainly employed as an upconversion luminescence (UCL) imaging agent, whereas the Bi nanoparticles worked as an effective CT imaging and photothermal agent. Importantly, a dense SiO 2 shell was employed to protect the Bi nanoparticles from oxidation, and it also endowed the nanoplatform with excellent hydrophilic ability. The effective UCL/CT imaging and PTT performances were emphasized by a series of in vivo experiments, which suggest that the integrated nanoplatform with imaging and therapy functions shows great promise in the biomedical field.

Monodisperse YF 3 and YOF porous sub-microspheres were synthesized by using a novel sacrificing template method with amorphous Y(OH)CO 3 ⋅x H 2 O as the precursors and the template. It was found that the size and shape were well maintained, and the condensed precursor was transformed into uniform porous structures after fluoridation. By fine-tuning the feed of the fluorine source, the final product could be converted from YF 3 to YOF. A possible growth mechanism is proposed for the uniform porous YF 3 structure and the porous yolk-shell-like YOF structure. The luminescence properties showed that the as-synthesized YF 3 :Ln 3+ (Ln=Eu, Tb, Ce, Ce/Tb, Yb/Er, Yb/Ho, and Yb/Tm) products exhibited strong multicolor emissions, which included down-/upconversion and energy-transfer processes. Additionally, YOX (X=Cl and Br) could be obtained if a different halogen source was used during calcination. However, the spheres were almost completely destroyed. Our novel synthetic route can also be extended to other lanthanide fluorides (REF 3 , RE=Gd, Lu), which may open a facile way to fabricate novel porous nanostructures., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A novel aqueous-based and phase-selected synthetic strategy toward YPO 4 :Ln 3+ (Ln = Ce, Eu, Tb) micro/nanocrystals was developed by selecting specific precursors whose structure topotactically matches with the target ones. It was found that layered yttrium hydroxide (LYH) induced the formation of hexagonal-phased h-YPO 4 ·0.8H 2 O with the crystalline relationship of [001]LYH//[0001]h-YPO 4 ·0.8H 2 O, while the amorphous Y(OH)CO 3 favored the formation of tetragonal-phased t-YPO 4 . We also systematically investigated the influence of Na 2 CO 3 /NaH 2 PO 4 feeding ratio on the evolutions of morphology and size of the h-YPO 4 ·0.8H 2 O sample, and we also obtained a novel mesoporous nanostructure for t-YPO 4 single crystalline with closed octahedron shape for the first time. Besides, the multicolor and phase-dependent luminescence properties of the as-obtained h-YPO 4 ·0.8H 2 O and t-YPO 4 micro/nanocrystals were also investigated in detail. Our work may provide some new guidance in synthesis of nanocrystals with target phase structure by rational selection of precursor with topotactic structural matching.