Monodisperse lanthanide oxyfluorides LnOF (Ln = Y, La, Pr-Tm): morphology controlled synthesis, up-conversion luminescence and in vitro cell imaging

The synthesis and multicolor luminescence of lanthanide doped Vernier lutetium oxyfluorides

We report a facile hydrothermal method followed by heat treatment for synthesizing monodispersed V-LuOF nanorods through which multicolor emissions are achieved in V-LuOF:Tb³⁺,xEu³⁺.

One-step surfactant-free controllable synthesis and tunable up-conversion/down-shifting white light emissions of Sr2YF7 crystals doped with Ln3+ ions

In this work, uniform and monodisperse Sr₂YF₇ spheres were successfully synthesized via a facile one-step hydrothermal route without employing any surfactant.

Phytosynthesis of nearly monodisperse CuO nanospheres using Phyllanthus reticulatus/Conyza bonariensis and its antioxidant/antibacterial assays

In the present article we have developed an eco-friendly, phytosynthetic, cost-effective and straightforward method for the synthesis of nearly monodisperse CuO nanospheres (NSP) using leaf extracts of medicinal plants Phyllanthus reticulatus (PR) and Conyza bonariensis (CB) as novel green reducing agents. Copper nitrate (Cu (NO₃)₂) was used as a precursor. The stoichiometric ratio of both leaf extracts (PR/CB) and Cu(NO₃)₂ was standardized for the synthesis of NSP. During formation of CuO NSP, a color of solution gradually changed from light greenish-blue to black with a number of intermediate stages and it correlated to the reduction reaction catalyzed by phytochemicals. As-synthesized materials were characterized in detail at the structural, electronic level and morphological authentication by XRD, FT-IR, EDS, UV-DRS, Raman, XPS, SEM, TEM, BET and AFM. SEM studies of phytosynthesized materials revealed nearly monodisperse nanospheres, while TEM rendered average particles size 4-14 nm. Also, AFM profiles suggested a homogenized nature of the nanospheres. Then, the antioxidant property was obtained by α, α-diphenyl-β-picrylhydrazyl (DPPH). Ethanolic, methanolic extracts were used for the antioxidant activity, while ascorbic acid was used as a standard medium. Each plant extract exhibited noteworthy antioxidant activity. Moreover, the antibacterial activity of CuO NSP (PR/CB) was tested against human pathogenic bacteria viz. gram-positive Staphylococcus aureus, Klebsiella pneumoniae, and gram-negative Escherichia coli. Result rendered effective antibacterial activity against Escherichia coli.

Applications of nanoparticles in biomedical imaging

An urgent need for early detection and diagnosis of diseases continuously pushes the advancements of imaging modalities and contrast agents. Current challenges remain for fast and detailed imaging of tissue microstructures and lesion characterization that could be achieved via development of nontoxic contrast agents with longer circulation time. Nanoparticle technology offers this possibility. Here, we review nanoparticle-based contrast agents employed in most common biomedical imaging modalities, including fluorescence imaging, MRI, CT, US, PET and SPECT, addressing their structure related features, advantages and limitations. Furthermore, their applications in each imaging modality are also reviewed using commonly studied examples. Future research will investigate multifunctional nanoplatforms to address safety, efficacy and theranostic capabilities. Nanoparticles as imaging contrast agents have promise to greatly benefit clinical practice.

Size of the rare-earth ions: a key factor in phase tuning and morphology control of binary and ternary rare-earth fluoride materials

An IL based solvothermal route to prepare RE ion doped luminescent binary/ternary fluoride nanomaterials. Size of the RE ions tunes the nature of the product, crystal phase, lattice strain and morphology, effecting the luminescence properties.

Controllable Synthesis of Monodisperse Er3+-Doped Lanthanide Oxyfluorides Nanocrystals with Intense Mid-Infrared Emission

Monodisperse lanthanide oxyfluorides LnOF (Ln = Gd, Y) with mid-infrared emissions were controllably synthesized via a mild co-precipitation route and a subsequent heat-treatment. The detailed composition and morphology were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and high resolution transmission electron microscopy (HRTEM). The results showed that monodisperse GdOF:Er³⁺ were nano-riced shape with length about 350 nm and width about 120 nm, while the quasi-spherical YOF:Er³⁺ were uniform nanocrystals with an average size around 100 nm. The influence of calcination temperature on the size and phase transition of LnOF nanocrystals was also investigated. The photoluminescence (PL) spectra indicated that the 2.7 μm emission of Er³⁺ had achieved in both GdOF and YOF nanocrystals, which were calcined at different temperatures. In addition, the decay time of both ⁴I_13/2 and ⁴I_13/2 energy levels corresponding to Er³⁺ in YOF nanocrystals were also studied in detail. The results suggested that both rice-shaped GdOF nanocrystals and YOF nanocrystals could provide suitable candidate materials for nanocrystals-glass composites, which could be a step forward to the realization of mid-infrared laser materials.

Rapid, morphology-controllable synthesis of GdOF:Ln3+ (Ln = Eu, Tb) crystals with multicolor-tunable luminescence properties

This work investigates a facile and mass-production method to synthesize multiform morphologies of GdOF and obtains multicolor emissions in GdOF:Tb³⁺,Eu³⁺ samples.

Highly improved upconversion luminescence in NaGd(WO₄)₂:Yb³⁺/Tm³⁺ inverse opal photonic crystals

The upconversion luminescence (UCL) of rare earth (RE) ions doped nanomaterials has attracted extensive interest because of its wide and great potential applications. However, the lower UCL efficiency is still an obstacle for real applications. Photonic modulation is a novel way to improve the efficiency of UCL. In this work, NaGd(WO4)2:Yb(3+)/Tm(3+) inverse opal photonic crystals (IOPCs) were fabricated through the polymethylmethacrylate (PMMA) template and the modification of the IOPC structure on the emission spectra and dynamics of Tm(3+) ions was systemically studied. It is interesting to observe that in the IOPCs, the high-order UCL (1)D2-(3)H6/(3)F4 was relatively enhanced. At the same time, the local thermal effect induced by laser irradiation was suppressed. Furthermore, the overall intensity ratio of visible UCL to near-infrared (NIR) down-conversion luminescence (DCL) was 2.8-8 times improved than that of the grinded reference (REF) and independent of the photonic stop band (PSB). The studies on UCL dynamics indicated that the nonradiative transition rate of Tm(3+) was considerably suppressed. The facts above indicated that in the IOPCs the UCL efficiency of Tm(3+) was largely improved due to the periodic macroporous structure.

A novel synthetic route towards monodisperse LaOF:Ln3+ (Ln = Eu, Tb) hollow spheres with multicolor luminescence properties

This work investigates a novel facile synthesis strategy for the LaOF hollow spheres to obtain multicolor emissions in LaOF:Tb³⁺,Eu³⁺ samples.

Highly modified spontaneous emission in NaY(MoO4)2:Yb3+/Er3+ inverse opal photonic crystals

NaY(MoO₄)₂:Yb³⁺/Er³⁺ inverse opal photonic crystals were fabricated and the UCL efficiency of Er³⁺ was improved due to the periodic macroporous structure.

KF-mediated controlled-synthesis of potassium ytterbium fluorides (doped with Er3+) with phase-dependent upconversion luminescence

Potassium ytterbium fluorides with predictable crystal phases and architectures have been successfully synthesized by simply tuning the molar ratio of KF to Yb³⁺via a facile and general solution-based approach.