Dodecahedral hollow multi-shelled Co3O4/Ag:ZnIn2S4 photocatalyst for enhancing solar energy utilization efficiency.

Employing semiconductor photocatalysts featuring a hollow multi-shelled (HoMs) structure to establish a heterojunction is an effective approach to addressing the issues of low light energy utilization and severe recombination of photogenerated charge carriers. To take advantage of these key factors in semiconductor photocatalysis, here, a dodecahedral HoMs Co3O4/Ag:ZnIn2S4 photocatalyst (denoted as Co3O4/AZIS) was firstly synthesized by coupling Ag+-doped ZnIn2S4 (AZIS) nanosheets with dodecahedral HoMs Co3O4. The unique HoMs structure of the photocatalyst can not only effectively promote the separation and transfer of photo-induced charge, but also improve the utilization rate of visible light, exposing rich active sites for the photocatalytic redox reaction. The photocatalytic experiment results showed that the Co3O4/90.0 wt% AZIS photocatalyst has a high hydrogen (H2) production rate (695.0 µmol h-1 g-1) and high methyl orange (MO) degradation rate (0.4243 min-1). This work provides a feasible strategy for the development of HoMs heterojunction photocatalysts with enhanced H2 production and degradation properties of organic dyes.

Composites of W18O49 Nanowires with g-C3N4/RGO Nanosheets for Broadband Light-Driven Photocatalytic Wastewater Purification.

Developing a photocatalyst that can effectively utilize the full solar spectrum remains a high-priority objective in the ongoing pursuit of efficient light-to-chemical energy conversion. Herein, the ternary nanocomposite g-C3N4/RGO/W18O49 (CN/RGO/WO) was constructed and characterized by a variety of techniques. Remarkably, under the excitation of photon energies ranging from the ultraviolet (UV) to the near-infrared (NIR) region, the photocatalytic performance of the CN/RGO/WO nanocomposite exhibited a significant enhancement compared with single component g-C3N4 or W18O49 nanosheets for the degradation of methyl orange (MO). The MO photodegradation rate of the optimal CN/1.0 wt% RGO/45.0 wt% WO catalyst reached 0.816 and 0.027 min-1 under UV and visible light excitation, respectively. Even under low-energy NIR light, which is not sufficient to excite g-C3N4, the MO degradation rate can still reach 0.0367 h-1, exhibiting a significant enhancement than pure W18O49. The outstanding MO removal rate and stability were demonstrated by CN/RGO/WO nanocomposites, which arise from the synergistic effect of localized surface plasmon resonance effect induced by W18O49 under vis-NIR excitation and the Z-scheme nanoheterojunction of W18O49 and g-C3N4. In this work, we have exploited the great potential of integrating nonmetallic plasmonic nanomaterials and good conductor RGO to construct high-performance g-C3N4-based full-solar spectral broadband photocatalysts.

Coevolution between marine Aeromonas and phages reveals temporal trade-off patterns of phage resistance and host population fitness.

Coevolution of bacteria and phages is an important host and parasite dynamic in marine ecosystems, contributing to the understanding of bacterial community diversity. On the time scale, questions remain concerning what is the difference between phage resistance patterns in marine bacteria and how advantageous mutations gradually accumulate during coevolution. In this study, marine Aeromonas was co-cultured with its phage for 180 days and their genetic and phenotypic dynamics were measured every 30 days. We identified 11 phage resistance genes and classified them into three categories: lipopolysaccharide (LPS), outer membrane protein (OMP), and two-component system (TCS). LPS shortening and OMP mutations are two distinct modes of complete phage resistance, while TCS mutants mediate incomplete resistance by repressing the transcription of phage genes. The co-mutation of LPS and OMP was a major mode for bacterial resistance at a low cost. The mutations led to significant reductions in the growth and virulence of bacterial populations during the first 60 days of coevolution, with subsequent leveling off. Our findings reveal the marine bacterial community dynamics and evolutionary trade-offs of phage resistance during coevolution, thus granting further understanding of the interaction of marine microbes.

Design combinations of evolved phage and antibiotic for antibacterial guided by analyzing the phage resistance of poorly antimicrobial phage.

Although antibiotics are the primary method against bacterial infections, the rapid emergence of antibiotic resistance has forced interest in alternative antimicrobial strategies. Phage has been considered a new biological antimicrobial agent due to its high effectiveness in treating bacterial infections. However, the applications of phage therapy have been limited by the quick development of phage-resistant bacteria. Therefore, more effective phage treatment strategies need to be explored guided by characterizing phage-resistant mutants. In this study, Pseudomonas plecoglossicida phage vB_PpS_SYP was isolated from the sewage but exhibited weak antibacterial activity caused by phage-resistant bacteria. Phage-resistant mutants were isolated and their whole genomes were analyzed for differences. The results showed that mutations in glycosyltransferase family 1 (GT-1) and hypothetical outer membrane protein (homP) led to bacterial phage resistance. The GT-1 mutants had lower biofilm biomass and higher antibiotic sensitivity than wild-type strain. Phage SYP evolved a broader host range and improved antimicrobial efficacy to infect homP mutants. Therefore, we designed a strategy for combined antibiotic and evolved phage inhibition driven by the two phage-resistant mutants. The results showed that the combination was more effective against bacteria than either antibiotics or phage alone. Our findings presented a novel approach to utilizing poorly antimicrobial phages by characterizing their phage-resistant mutants, with the potential to be expanded to include phage therapy for a variety of pathogens. IMPORTANCE The rapid emergence of antibiotic resistance renews interest in phage therapy. However, the lack of efficient phages against bacteria and the emergence of phage resistance impaired the efficiency of phage therapy. In this study, the isolated Pseudomonas plecoglossicida phage exhibited poor antibacterial capacity and was not available for phage therapy. Analysis of phage-resistant mutants guided the design of antibacterial strategies for the combination of antibiotics with evolved phages. The combination has a good antibacterial effect compared to the original phage. Our findings facilitate ideas for the development of antimicrobial-incapable phage, which have the potential to be applied to the phage treatment of other pathogens.

The construction of a heterostructured RGO/g-C3N4/LaCO3OH composite with enhanced visible light photocatalytic activity for MO degradation.

The construction of a heterojunction and the introduction of a cocatalyst can both promote the transfer of photogenerated electrons, which are effective strategies to enhance photocatalytic efficiency. In this paper, a ternary RGO/g-C3N4/LaCO3OH composite was synthesized by constructing a g-C3N4/LaCO3OH heterojunction and introducing a non-noble metal cocatalyst RGO through hydrothermal reactions. TEM, XRD, XPS, UV-vis diffuse reflectance spectroscopy, photo-electrochemistry and PL tests were carried out to characterize the structures, morphologies and carrier separation efficiencies of products. Benefiting from the boosted visible light absorption capability, reduced charge transfer resistance and facilitated photogenerated carrier separation, the visible light photocatalytic activity of the ternary RGO/g-C3N4/LaCO3OH composite was effectively improved, resulting in a much increased MO (methyl orange) degradation rate of 0.0326 min-1 compared with LaCO3OH (0.0003 min-1) and g-C3N4 (0.0083 min-1). Moreover, by combining the results of the active species trapping experiment with the bandgap structure of each component, the mechanism of the MO photodegradation process was proposed.

φC31 -Mediated cassette exchange in Sf9 insect cells for stable expression.

Insect cells, especially Sf9 cells, are commonly used in biomanufacturing due to their advantages in high expression levels and post-translational modification. However, the development of stable expression cell lines via random integration tended to be unstable. Site-specific integration (SSI) is an alternative strategy. In this study, a φC31 -mediated cassette exchange system in Sf9 cells was established for SSI. The tagging cassette with the reporter gene egfp was randomly inserted into the cell genome. Potential platform cell lines were obtained by fluorescence-activated cell sorting (FACS) and single-cell cloning. Platform cell lines were selected by assessing the fluorescence expression, stability, and growth kinetics of cell lines. The selected platform cell lines were co-transfected with the φC31-containing plasmid and the targeting cassette. Green-fluorescence-negative clones were screened by hygromycin resistance and FACS. The resulting cell clones exhibited the expression properties of the platform cell lines. The rapid development of cell lines for the production of influenza subunit vaccines by the cassette exchange system demonstrated that the system constituted a versatile and reusable platform for the production of various recombinant proteins. Overall, the φC31-mediated cassette exchange system in Sf9 cells has the potential to facilitate and accelerate biologics development.

YBac: A novel and simple baculovirus system for heterologous protein production in Spodoptera frugiperda 9 (Sf9) cells.

The baculovirus expression vector system (BEVS) has been widely used for heterologous protein expression due to its powerful functionality and easy access to commercial expression vectors. Currently, most laboratories prefer two strategies for protein production using BEVS. One is recombinant bacmid based on transposition in Escherichia coli (e.g., Bac-to-Bac), and another is homologous recombination in insect cells (e.g., flashBac). In this manuscript, a rapid and simple YBac system was established. This novel system uses an Ac99KO bacmid as a virus vector and co-transfected into Spodoptera frugiperda 9 (Sf9) cells with a donor plasmid capable of recombination into Ac42 loci that carry the genes of interest (GOIs) along with the complete Ac99 fragment. Based on the intracellular homologous recombination system, the production of foreign proteins was achieved by the complementation of the Ac99 gene together with the insertion of GOIs. In this study, the human thyroid peroxidase (hTPO) and porcine epidemic diarrhea virus-like particles (PEDV VLPs) were successfully expressed using the YBac system. The entire process was shortened to 10 days, and the components involved in the system could be easily prepared in the laboratory, suggesting that the YBac system may have great potential in the production of heterologous proteins.

Genome-wide nonessential gene identification of Autographa californica multiple nucleopolyhedrovirus.

The Baculovirus Expression Vector System (BEVS) is an insect cell-based heterologous protein expression system that possesses powerful potential in the development of protein drugs and vaccines. Autographa californica multiple nucleopolyhedrovirus (AcMNPV) is the most widely-used vector in BEVS with 151 open reading frames (ORFs) containing essential and nonessential genes. Deletion of nonessential genes has many advantages including increased foreign gene insertion. In this study, the λ red recombination system was used to knock out genes in a modified AcMNPV that carried an enhanced yellow fluorescent protein (eYFP) at the Ac126-Ac127 locus. Eighty genes were almost completely deleted respectively and 69 gene knockout AcMNPVs (KOVs) were obtained to evaluate their infection efficiency. After infecting Spodoptera frugiperda 9 (Sf9) cells, 51 KOVs including 62 genes showed similar infectivity as wide type (WT) and hence were defined as nonessential genes. However, 18 KOVs produced fewer infectious virions, indicating that these genes were influential in the production of progeny viruses. Combining our research with previous studies, a desired minimal AcMNPV genome containing 86 ORFs and all of the homologous regions (hrs) was brought up, facilitating genetic modification of baculovirus vectors and improvement of recombinant protein expression in the future.

A lef5-deficient baculovirus expression system with no virion contamination and promoting secretion.

The baculovirus expression system (BEVS) is widely used in biomanufacturing. However, massive late and very late genes are expressed during baculovirus infection of the host cell, and the protein aggregation has a significant negative impact on the intercellular environment of cells and organelle function. Baculovirus particle contamination also hinders the purification of particulate products. In this study, a novel baculovirus vector of deficient-lef5 (Ac-Δlef5) was established to prevent the production of baculovirus particles. It could transduce cells and replicate viral DNA but the expression of the late and very late genes was reduced so that no virus was packed and budded. The Ac-Δlef5 expression system was successfully used to express a secreted protein, thyroid peroxidase (TPO). Compared to wild-type baculovirus (Ac-wt), Ac-Δlef5 delayed the decline in cell viability and prolonged the harvest period from 4 to 6 days after infection. When expressed in the Ac-Δlef5 system, 98% of TPO was secreted extracellularly, which was about 1.8 times that of the Ac-wt system. Meanwhile, the transcription levels of protein folding-related genes were significantly increased. The results show that the Ac-Δlef5 system is a potential novel viral-free baculovirus expression system, which omits the virion removal operation in biomanufacturing.

Shelf-life prediction and storage stability of Aeromonas bacteriophage vB_AsM_ZHF.

Phage therapy is a potential alternative to antibiotics for the treatment of bacterial infections. Due to the good antibacterial and therapeutic effects of phages, phage therapy has received attention and the demand for clinical applications has gradually increased. Phage storage stability and shelf life are key aspects of biopharmaceutical development and registration. In this study, Aeromonas salmonicida phage was stored at different temperatures for 12 months. We found that 4 °C was the optimal storage temperature. In the case of cryopreservation, 10% dimethyl sulfoxide (DMSO) was more effective at protecting the phage at -20 °C and -80 °C than 30% glycerin. Indeed, the phage titer decreased by only one order of magnitude within one year when DMSO was added. Hydroxyapatite (HAP) reduced the inactivation of phages by six orders of magnitude during storage at 28ºC for 1 year, significantly lower than that of in SM buffer. In addition, for excipients in lyophilization, tryptic soy broth (TSB) and tryptone or skim milk powder (SMP) in combination with trehalose alleviated phage inactivation during lyophilization and subsequent storage at 28 °C. Furthermore, a model for predicting the phage shelf-life was established with the Accelerated Stability Assessment Program (ASAP) based on the Arrhenius equation. The error of the model was less than 15% by comparing the predicted value with the actual value at 28 °C, indicating high accuracy. The study demonstrated the storage stability and shelf-life model of phage for the first time, which provided a theoretical basis for the development and application of phage products.

Therapeutic efficacies of two newly isolated Edwardsiella phages against Edwardsiella piscicida infection.

The spread of multi-drug resistant (MDR) bacteria has posed a threat to the development of aquaculture. Due to its effective bactericidal ability, phage therapy has been considered as an alternative to antibiotics to reduce infection caused by MDR bacteria. In this study, two Edwardsiella piscicida phages were newly-isolated and characterized to prevent or treat infection in aquaculture. The phages were designated as vB_EpM_ZHS and vB_EpP_ZHX belonging to Myoviridae and Podoviridae families, respectively, in terms of genome sequence and morphology analyses. The combination of vB_EpM_ZHS and vB_EpP_ZHX improved the therapeutic efficacy both in vitro and in vivo. The phage cocktail significantly inhibited bacterial growth in vitro and decreased approximately 40% of mortality rate and an order of magnitude of bacterial burden in zebrafish and turbot infected by E. piscicida. Moreover, the phage cocktail increased transcription levels of tumor necrosis factor-alpha (TNF-α), interleukin-12 (IL-12), interleukin-6 (IL-6), and interleukin-1ß (IL-1ß) and alleviated inflammatory levels in the hindgut and spleen of turbots. The results indicate that the phage has a promising potential for therapeutic use against E. piscicida as the antimicrobial alternative to antibiotics in aquaculture.

Isolation of a Virulent Aeromonas salmonicida subsp. masoucida Bacteriophage and Its Application in Phage Therapy in Turbot (Scophthalmus maximus).

Aeromonas salmonicida is an aquatic pathogen that can infect a variety of fish. Phage therapy has been applied to treat bacterial infections. In this study, we obtained three A. salmonicida subsp. masoucida phage isolates from sewage, and one phage (vB_AsM_ZHF) exhibited the best antibacterial effect, based on in vitro kinetics experiments. Sequencing indicated that the vB_AsM_ZHF genome is 161,887 bp (41.24% C+G content) with 237 predicted open reading frames. No antibiotic resistance or virulence genes were detected in the complete genome, which is a requirement for phage therapy safety. Intraperitoneal injection of phage vB_AsM_ZHF into turbot at 8 × 104 PFU/fish rescued turbot from A. salmonicida subsp. masoucida injection and reduced the bacterial burden by 1 order of magnitude. Injection of vB_AsM_ZHF also decreased levels of inflammatory cell infiltration in muscle tissue, cytokines interleukin-1ß (IL-1ß), tumor necrosis factor alpha (TNF-α), and gamma interferon (IFN-γ) in serum and the expression of the inflammatory factors IL-1ß, IL-6, IFN-γ, transforming growth factor ß, TNF-α, and hepcidin in the liver, spleen, and head kidney of turbot. Phage vB_AsM_ZHF demonstrated antibacterial ability in vitro and in vivo and significantly reduced mortality in turbot challenged by A. salmonicida subsp. masoucida. This study revealed that phage vB_AsM_ZHF can effectively treat the infection caused by A. salmonicida subsp. masoucida in turbot. IMPORTANCEA. salmonicida is an aquatic pathogen that can infect different fish and causes economic loss to the global aquaculture industry. Clinical strains of A. salmonicida have developed multidrug resistance, and phage therapy is being evaluated for controlling bacterial infections. Phages are biological antibacterial agents and have the potential to be therapeutic agents against multidrug-resistant bacteria. In this study, three A. salmonicida subsp. masoucida phages were isolated from sewage, and their biological behaviors were characterized. The newly isolated phage vB_AsM_ZHF could inhibit A. salmonicida subsp. masoucida infection in vitro and in vivo, suggesting that it may be an alternative strategy to antibiotics for protecting fish against multidrug-resistant A. salmonicida subsp. masoucida in the aquaculture industry.

Designing 2D-2D g-C3N4/Ag:ZnIn2S4 nanocomposites for the high-performance conversion of sunlight energy into hydrogen fuel and the meaningful reduction of pollution.

The generation of hydrogen-based energy and environmental remediation using sunlight is an emerging topic of great significance for meeting the ever-growing global need. However, the actual photocatalytic performance is still far below expectations because of the relatively slack charge-carrier separation and migration as well as insufficient spectral absorption in semiconductors. Therefore, the rational construction of heterojunctions is considered as an effective approach to solving the above issues. In this context, we have, for the first time, designed and synthesized a two-dimensional 2D-on-2D heterostructure, based on 2D Ag-doped ZnIn2S4 nanoplates deposited on 2D g-C3N4 nanosheets (denoted as g-C3N4/Ag:ZnIn2S4). This construct benefits from improved visible-light absorption by unveiling a greater number of catalytically active sites, effectively enhancing charge-carrier separation and relocation. Detailed analysis has proved that under visible-light irradiation, the optimized g-C3N4/20 wt% Ag:ZnIn2S4 nanocomposite has substantially upgraded photocatalytic activity in hydrogen formation by water splitting (hydrogen evolution rate of up to 597.47 µmol h-1 g-1) and in residual dyestuff degradation (methyl orange, MO; degradation rate constant of 0.1406 min-1). Noteworthily, these two exceptionally high values respectively represent 30.73 and 5.42 times enhancements vs. results obtained with bare g-C3N4. Another strong point of our g-C3N4/Ag:ZnIn2S4 is its impressive recyclability for 20 runs, with no relevant metal release in the aqueous solution following photocatalysis. This work introduces new, superior access to highly efficient photocatalysts founded on 2D/2D nanocomposites serving both the production of hydrogen as an energy carrier and environmental remediation.

In situ growth of CuS nanoparticles on g-C3N4 nanosheets for H2 production and the degradation of organic pollutant under visible-light irradiation.

The solar-to-fuel conversion using a photocatalyst is an ideal method to solve the energy crisis and global warming. In this contribution, photocatalytic H2 production and organic pollutant removal using g-C3N4/CuS composite was demonstrated. Well dispersed CuS nanoparticles (NPs) with a size of about 10 nm were successfully grown on the surface of g-C3N4 nanosheet via a facile hydrothermal method. The as-prepared g-C3N4/CuS nanocomposite at an optimized loading exhibited a much higher visible light photoactivity, giving up to 2.7 times and 1.5 times enhancements in comparison to pure g-C3N4 for photocatalytic H2 production and methylene orange (MO) degradation, respectively. These enhanced photocatalytic activities are attributed to the interfacial transfer of photogenerated electrons and holes between g-C3N4 and CuS, which leads to effective charge separation on both parts. That is, under the visible light irradiation, electrons in the valence band (VB) of g-C3N4 can directly transfer to the CuS NPs, which can act as an electron sink and co-catalyst to promote the separation and transfer of photo-generated electrons, thus significantly improving the photocatalytic efficiency.

Facile Synthesis of GdF3:Yb3+, Er3+, Tm3+@TiO2-Ag Core-Shell Ellipsoids Photocatalysts for Photodegradation of Methyl Orange Under UV, Visible, and NIR Light Irradiation.

To enhance solar energy utilization efficiency, goal-directed design of architectures by combining nanocomponents of radically different properties, such as plasmonic, upconversion, and photocatalytic properties may provide a promising method to utilize the most energy in sunlight. In this work, a new strategy was adopted to fabricate a series of plasmonic Ag nanoparticles decorated GdF3:Yb3+, Er3+, Tm3+-core@porous-TiO2-shell ellipsoids, which exhibit high surface area, good stability, broadband absorption from ultraviolet to near infrared, and excellent photocatalytic activity. The results showed that photocatalytic activities of the as-obtained photocatalysts was higher than that of pure GdF3:Yb3+, Er3+, Tm3+ and GdF3:Yb3+, Er3+, Tm3+@TiO2 samples through the comparison of photodegradation rates of methyl orange under UV, visible, and NIR irradiation. The possible photocatalytic mechanism indicates that hydroxyl radicals and superoxide radical play a pivotal role in the photodegradation. Furthermore, the materials also showed exceptionally high stability and reusability under UV, visible, and NIR irradiation. All these results reveal that core-shell hierarchical ellipsoids exhibit great prospects for developing efficient solar photocatalysts.

Uniform and Well-Dispersed LuBO3 Hollow Microspheres: Synthesis, Formation and Photoluminescence Properties.

A hard template strategy is developed to fabricate the LuBO3: Eu3+/Tb3+ hollow microspheres using a novel multi-step transformation synthetic route for the first time with polystyrene (PS) spheres as the template, followed by the combination of a facile homogeneous precipitation method, an ion-exchange process, and a calcination process. The results show that the as-obtained LuBO3: Eu3+/Tb3+ hollow spheres have a uniform morphology with an average diameter of 1.8 µm and shell thickness of about 80 nm. When used as luminescent materials, the emission colors of LuBO3: Eu3+/Tb3+ samples can be tuned from red, through orange, yellow and green-yellow, to green by simply adjusting the relative doping concentrations of the activator ions under the excitation of ultraviolet (UV) light, which might have potential applications in the field such as light display systems and optoelectronic devices.

Plasmonic Au-Loaded Hierarchical Hollow Porous TiO2 Spheres: Synergistic Catalysts for Nitroaromatic Reduction.

Plasmonic Au nanoparticle (NP)-loaded hierarchical hollow porous TiO2 spheres are designed and synthesized with the purpose of enhancing the overall catalytic activity by introducing the Au plasmonic effect into the system, where Au NPs themselves are catalytically active. The constructed nanohybrid exhibits both high activity in 4-nitrophenol reduction, compared to all of the previously reported Au-based catalysts, and high selectivity. The synergy of the inherent catalytic property of Au NPs and the plasmonic effect (mainly via hot electron transfer) under irradiation is confirmed by a series of control experiments. The specifically designed, porous hollow structure also greatly contributes to the good catalytic activity because it provides a large surface area, facilitates reactant adsorption, and hinders charge recombination. In addition, theoretical calculations reveal that such a structure also leads to an increase in light absorption of about 21% in the range of 400-800 nm with respect to a uniform water-TiO2 background featuring the same filling factor. This work provides insight into the rational design of plasmon-enhanced catalysts that will show their versatility in various electro-/photocatalysis.

Assembly of thiacalix[4]arene-supported high-nuclearity Cd24 cluster with enhanced photocatalytic activity.

A high-nuclearity nanoscale Cd24 cluster has been hydrothermally synthesized by assembly of Cd4-TC4A (H4TC4A = p-tert-butylthiacalix[4]arene) second building units (SBUs) and in situ generated peroxy(mono)phosphate PO53- groups and peroxyphenoxide groups of TC4A. The cluster was structurally characterized by single crystal X-ray diffractions. Photocatalytic studies revealed that the highest nuclearity Cd,S-co-rich Cd24 cluster exhibits enhanced photocatalytic water splitting activities compared to the sandwich Cd4(TC4A)2 (Cd4) cluster under the same conditions in the absence of a co-catalyst. The nanostructure of Cd24 incorporated both peroxyphosphate and peroxyphenoxide groups, which increased the metal coordination numbers to give more labile Cd-O/S bonds and is believed to be the key feature that enables the significant photocatalytic water splitting activities.

Large-scale fabrication of porous YBO3 hollow microspheres with tunable photoluminescence.

Hollow lanthanide-doped compounds are some of the most popular materials for high-performance luminescent devices. However, it is challenging to find an approach that can fabricate large-scale and well-crystallized lanthanide-doped hollow structures and that is facile, efficient and of low cost. In this study, YBO3: Eu3+/Tb3+ hollow microspheres were fabricated by using a novel multi-step transformation synthetic route for the first time with polystyrene spheres as the template, followed by the combination of a facile homogeneous precipitation method, an ion-exchange process and a calcination process. The results show that the as-obtained YBO3: Eu3+/Tb3+ hollow spheres have a uniform morphology with an average diameter of 1.65 µm and shell thickness of about 160 nm. When used as luminescent materials, the emission colours of YBO3: Eu3+/Tb3+ samples can be tuned from red, through orange, yellow and green-yellow, to green by simply adjusting the relative doping concentrations of the activator ions under the excitation of ultraviolet light, which might have potential applications in fields such as light display systems and optoelectronic devices.

Facile Synthesis and Down-Conversion Emission of RE3+-Doped Lutetium Oxide Nanoparticles.

Lu2O3:RE3+ (RE3+ = Eu3+, Tb3+, Ho3+) nanoparticles have been successfully synthesized by a facile homogeneous precipitation method with subsequent sintering process. The crystal structure, morphology and luminescence properties of the as-prepared samples have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), photoluminescence (PL) and cathodoluminescence (CL) spectra. Upon ultraviolet (UV) and low-voltage electron beam excitation, Lu2O3:RE3+ (RE3+ = Eu3+, Tb3+, Ho3+) nanoparticles show strong red (Eu3+,5D0 → 7F2), green (Tb3+,5D4 → 7F5), and green (Ho3+,5S2 → 5I8) emissions. They exhibit a good advantage of multicolor emissions in the visible region, and endow these kinds of materials with potential application in many fields, such as light display systems, optoelectronic devices and biological imaging.