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Porcine epidemic diarrhea virus (PEDV) is a highly infectious pathogen with a high mortality rate, which poses a serious threat to newborn piglets. A rapid, safe and effective vaccine is necessary for protecting pigs from PED infection. Nanoparticles have become molecular scaffolds for displaying soluble antigens due to their unique physical and chemical properties. Here, a vaccine candidate was based on the display of PEDV S1 protein on a mi3 nanoparticle platform using SpyTag/SpyCatcher technology. The size, zeta potential and microstructure of the S1-mi3 NPs were investigated, and their effects on the uptake of antigen-presenting cells (APCs) and maturation of dendritic cells (DCs) were analyzed. Mice were immunized via muscular and intranasal administrations, and the levels of humoral, cellular and mucosal immune responses were analyzed. As a result, S1 proteins were surface-displayed on NPs successfully, which self-assembled into nanoparticles composed of 60 subunits and showed superior safety and stability. In addition, mi3 NPs promoted antigen internalization and dendritic cell (DCs) maturation. In the mouse model, S1-mi3 NPs significantly increased the PEDV-specific antibody including serum IgG, secretory IgA (SIgA) and neutralizing antibodies (NAb). Furthermore, S1-mi3 NPs elicited more CD3+CD4+ and CD3+CD8+ T cell and cellular immune-related cytokines (IFN-γ and IL-4) compared to monomeric S1. In particular, it can induce an effective germinal center-specific (GC) B cell response, which is closely related to the production of neutralizing antibodies. Overall, S1-mi3 NPs are a promising subunit vaccine candidate against PEDV, and this self-assembly NPs also provide an attractive platform for improving vaccine efficacy against emerging pathogens. ● S1-mi3 nanoparticles significantly enhance humoral, mucosal and cellular immune responses. ● Nanoparticle-based S1 vaccine induces high-level neutralizing antibodies. ● S1-mi3 NPs elicit potent GC B cell responses in vivo. ● mi3 NPs promote the internalization and retention of S1 protein. [ABSTRACT FROM AUTHOR]

Porcine Epidemic diarrhea virus (PEDV), which can result in severe vomiting, diarrhea, dehydration and death in newborn piglets, poses a great threat to the pig industry around the world. The S1 subunit of S protein is crucial for triggering neutralizing antibodies binding to the receptor. Based on the advantages of high immunogenicity and precise assembly of nanoparticles, the mi3 nanoparticles and truncated S1 protein were assembled by the SpyTag/SpyCatcher system and then expressed in HEK293F cells, whereafter high-efficiency monoclonal antibodies (mAbs) were produced and identified. The obtained five mAbs can bind to various genotypes of PEDV, including a mAb (12G) which can neutralize G1 and G2 genotypes of PEDV in vitro. By further identification of monoclonal antibody target sequences, 507FNDHSF512 and 553LFYNVTNSYG562 were first identified as B-cell linear epitopes, in which 553LFYNVTNSYG562 was a neutralizing epitope. Alanine scans identified the key amino acid sites of two epitopes. Moreover, the results of multiple sequence alignment analysis showed that these two epitopes were highly conserved in various subtype variants. In brief, these findings can serve as a basis for additional research of PEDV and prospective resources for the creation of later detection and diagnostic techniques. • Highly immunogenic S1 protein nanoparticle was produced. • High-titer mAbs induced by S1 protein nanoparticle were generated, and a mAb 12G can neutralize G1 and G2 genotypes of PEDV in vitro. • 507FNDHSF512 and 553LFYNVTNSYG562 were first identified as B-cell linear epitopese, and the key amino acid sites were identified. [ABSTRACT FROM AUTHOR]

Porcine Epidemic diarrhea virus (PEDV), which can result in severe vomiting, diarrhea, dehydration and death in newborn piglets, poses a great threat to the pig industry around the world. The S1 subunit of S protein is crucial for triggering neutralizing antibodies binding to the receptor. Based on the advantages of high immunogenicity and precise assembly of nanoparticles, the mi3 nanoparticles and truncated S1 protein were assembled by the SpyTag/SpyCatcher system and then expressed in HEK293F cells, whereafter high-efficiency monoclonal antibodies (mAbs) were produced and identified. The obtained five mAbs can bind to various genotypes of PEDV, including a mAb (12G) which can neutralize G1 and G2 genotypes of PEDV in vitro. By further identification of monoclonal antibody target sequences, 507FNDHSF512 and 553LFYNVTNSYG562 were first identified as B-cell linear epitopes, in which 553LFYNVTNSYG562 was a neutralizing epitope. Alanine scans identified the key amino acid sites of two epitopes. Moreover, the results of multiple sequence alignment analysis showed that these two epitopes were highly conserved in various subtype variants. In brief, these findings can serve as a basis for additional research of PEDV and prospective resources for the creation of later detection and diagnostic techniques. • Highly immunogenic S1 protein nanoparticle was produced. • High-titer mAbs induced by S1 protein nanoparticle were generated, and a mAb 12G can neutralize G1 and G2 genotypes of PEDV in vitro. • 507FNDHSF512 and 553LFYNVTNSYG562 were first identified as B-cell linear epitopese, and the key amino acid sites were identified. [ABSTRACT FROM AUTHOR]

A novel N H TiO 2 photocatalyst was prepared via hydrothermal synthesis followed by a thermal treatment in NH 3 and H 2 atmospheres. The results showed that benzene with the initial concentration of 150 ppm (±5 ppm) could be thoroughly removed by N H TiO 2 under visible light irradiation. The influences of doping and hydrogenation on properties of TiO 2 samples were investigated. It is suggested that the disordered surface layer introduced by hydrogenation contributes to the excellent photocatalytic activity of N H TiO 2 . The synergistic effect of N doping and surface oxygen vacancies was also confirmed by ultraviolet–visible diffuse reflectance spectra and photoluminescence. Moreover, the diverse role of oxygen vacancies in different positions of TiO 2 has been focused on. [ABSTRACT FROM AUTHOR]

From modular vaccine production to protein assembly on nanoparticles, the SpyCatcher/SpyTag system provides a convenient plug-and-display procedure. Here, we established a general-purpose immunoaffinity chromatography (IAC) method for SpyTagged proteins (Spy&IAC). SpyTags are displayed on the surface of nanoparticles to induce high-affinity monoclonal antibodies, allowing the specific capture of the target protein. Taking the key core antigenic regions of two coronaviruses that are currently more threatened in the field of human and animal diseases, the nucleocapsid (N) protein of SARS-CoV-2 and the COE protein of porcine epidemic diarrhea virus (PEDV) as model proteins, a purification model with SpyTag at the N-terminal or C-terminal expressed in E. coli or mammalian cells was constructed. After the efficient elution of Spy&IAC, the final yield of several proteins is about 3.5–15 mg/L culture, and the protein purity is above 90 %. Purification also preserves the assembly function and immunogenicity of the protein to support subsequent modular assembly and immunization programs. This strategy provides a general tool for the efficient purification of SpyTagged proteins from different expression sources and different tag positions, enabling the production of modular vaccines at lower cost and in a shorter time, which will prepare the public health field for potential pandemic threats. [Display omitted] • The high-affinity monoclonal antibody was prepared by the multivalent display of nanoparticles. • An immunoaffinity chromatography method was established for the first time for the purification of SpyTagged proteins. • The assembly function and immunogenicity of elution SpyTagged protein were retained. [ABSTRACT FROM AUTHOR]

Background: The COVID-19 pandemic is a persistent global threat to public health. As for the emerging variants of SARS-CoV-2, it is necessary to develop vaccines that can induce broader immune responses, particularly vaccines with weak cellular immunity. Methods: In this study, we generated a double-layered N-S1 protein nanoparticle (N-S1 PNp) that was formed by desolvating N protein into a protein nanoparticle as the core and crosslinking S1 protein onto the core surface against SARS-CoV-2. Results: Vaccination with N-S1 PNp elicited robust humoral and vigorous cellular immune responses specific to SARS-CoV-2 in mice. Compared to soluble protein groups, the N-S1 PNp induced a higher level of humoral response, as evidenced by the ability of S1-specific antibodies to block hACE2 receptor binding and neutralize pseudovirus. Critically, N-S1 PNp induced Th1-biased, long-lasting, and cross-neutralizing antibodies, which neutralized the variants of SARS-CoV-2 with minimal loss of activity. N-S1 PNp induced strong responses of CD4+ and CD8+ T cells, mDCs, Tfh cells, and GCs B cells in spleens. Conclusions: These results demonstrate that N-S1 PNp vaccination is a practical approach for promoting protection, which has the potential to counteract the waning immune responses against SARS-CoV-2 variants and confer broad efficacy against future new variants. This study provides a new idea for the design of next-generation SARS-CoV-2 vaccines based on the B and T cells response coordination. [ABSTRACT FROM AUTHOR]

Optimizing the surface texture of silicon wafer to improve the light trapping performance and effective carrier lifetime of silicon surface is an efficient and low-cost way to enhance the energy conversion efficiency of mono-crystalline silicon PERC solar cells. In this paper, a simple method was adopted to prepare inverted pyramids with different sizes by varying the ρ value (ρ = [HF]/([HF]+[H 2 O 2 ]) of Cu metal assisted chemical etching (Cu-MACE) etching solution. The chemical mechanism of formation, etching rate, surface reflectivity, and effective minority carrier lifetime mapping of different silicon surface structures were systematically investigated. Moreover, the solar energy absorption rate of these different surface structures were studied by the finite difference time domain (FDTD) method. The results show that when the ρ value was between 25% and 90%, the etching rate of Cu nanoparticles increases with increasing ρ value. The final results reveal that the surface reflectivity, effective minority carrier lifetime and the light absorption were optimal when ρ∼75%, and the uniformity of corresponding inverted pyramid texture is the best. By utilizing the best inverted pyramid texture, the highest efficiency is 22.69%, corresponding Voc is 680.42 mV, Jsc is 41.20 mA/cm2, and FF is 80.94% on the 156.75 × 156.75 mm2 for large area mono-crystalline silicon PERC solar cell. • The optimized inverted pyramid structure were obtained. • The efficiency of such mono-Si PERC solar cells reached 22.68%. • The weighted average reflectance can be as low as 5.45%. • Various inverted pyramid structures prepared by a simple method. • FDTD solution were performed to evaluate the light absorption of different structural parameters. [ABSTRACT FROM AUTHOR]

Abstract: The composite of hollow glass microspheres coated by SnO2 nanoparticles has been successfully fabricated via sol-gel method. The phase structures, morphologies, particle size, shell thickness, chemical compositions of the composite have been characterized by XRD, FESEM, and EDX. The results show that SnO2 coating on hollow glass microspheres can be achieved, and the coating layers are constituted by SnO2 nanoparticles of mean size ca. 15 nm. The SnO2 coating layers grow thicker with the increased concentration of SnCl4. The effects of parameters (reaction temperature, concentration of NaOH and SnCl4, and time) were investigated to yield SnO2 coating on hollow glass microspheres, and the UV–vis absorption spectra of the composites were studied. [Copyright &y& Elsevier]

Abstract: Magnetite (Fe3O4) nanoparticles have been successfully synthesized by sol–gel method combined with annealing under vacuum. The phase structures, morphologies, particle sizes, chemical composition, and magnetic properties of Fe3O4 nanoparticles have been characterized by X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectrometer and vibrating sample magnetometer (VSM). The results indicate that the size, the corresponding saturation magnetization value and coercivity value of Fe3O4 nanoparticles increase with the increase of synthesized temperature. And the phase transformation of Fe3O4 nanoparticles has been studied under different atmospheres and temperatures. [Copyright &y& Elsevier]

Abstract: The silica nanolayer with different thickness was coated on the spherical cobalt nanoparticles (an average diameter of 67nm) to form core–shell structure by the controlled hydrolysis and condensation of tetraethyl orthosilicate (TEOS). This coating process was based on the use of silane coupling agent 3-mercaptopropyltrimethoxysilane (HS-(CH2)3Si(OCH3)3, MPTS) as a primer to render the cobalt surface vitreophilic, thus rendering cobalt surface compatible with silica. The control over the silica coating layer thickness can be achieved by varying the reaction time. The cobalt nanoparticles and the cobalt coated with silica shell were confirmed by transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) was used to gain insight into the way in which the MPTS is bound to the surface of the cobalt nanoparticles. Result of the thermogravimetric analysis (TGA) and differential thermal analysis (DTA) indicate that the thermal stability of cobalt/silica is better than that of pure cobalt nanoparticles. Magnetic properties of these powders have been evaluated. These cobalt/silica core–shell nanoparticles can be utilized as precursors for making property-tunable magnetic nanoparticles, thin films, and multilayered core–shell structure nanocomposites. [Copyright &y& Elsevier]

Abstract: Carbon fibers have been successfully coated with Fe3O4 nanoparticles coating layers via sol–gel method combined with annealing under vacuum. The phase structures and morphologies of the composite have been characterized by XRD and FESEM. The results show that a complete and uniform Fe3O4 nanoparticles coating on carbon fibers can be obtained in the temperature range of 300–550°C. The coating layers with thickness ca. 800nm are composed by Fe3O4 nanoparticles of mean sizes ca. 30nm. The surface properties of Fe3O4 nanoparticles detached from carbon fibers/Fe3O4 composite have been analyzed by XPS and FTIR. [Copyright &y& Elsevier]

Abstract: W/WS2 inorganic fullerene-like (IF) nanoparticles with core–shell structure are synthesized by the reaction of tungsten nanospheres and sulfur at relatively low temperatures (380–600°C) under hydrogen atmosphere, in which tungsten nanospheres were prepared by wire electrical explosion method. Images of transmission electron microscopy and high-resolution transmission electron microscopy show that the composite particles are of core–shell structure with spherical shape and the shell thickness is about 10nm. X-ray powder diffraction results indicate that the interlayer spacing of IF-WS2 shell decreases and approaches that of 2H-WS2 with increasing annealing temperatures, representing an expansion of 3.3–1.6%. A mechanism of IF-WS2 formation via sulfur diffusion into fullerene nanoparticles is discussed. Thermal analysis shows that the nanoparticles obtained at different temperatures exhibit similar thermal stability and the onset temperature of oxidization is about 410°C. Encapsulating hard tungsten core into IF-WS2 and the spherical shape of the core–shell structures may enhance their performance in tribological applications. [Copyright &y& Elsevier]

Abstract: SiO2-coated martensite stainless steel nanoparticles were prepared using wire electrical explosion technique combined with sol–gel technique, and their structural and magnetic properties were studied. The coating silica on stainless steel nanoparticles was based on the use of silane coupling agent 3-mercaptopropyltrimethoxysilane (HS-(CH2)3Si(OCH3)3, MPTS) as a primer to render the stainless steel surface vitreophilic, thus rendering stainless steel surface compatible with silica. The control over the silica coating layer thickness can be achieved by varying the reaction time. For stainless steel nanoparticles, their saturation and remnant magnetizations decreased upon silica coating, and their saturation magnetizations obviously decreased with increasing the thickness of SiO2 coating layer. These stainless steel/silica core–shell nanoparticles can be utilized as precursors for making property-tunable magnetic nanoparticles, thin films, and multilayered core–shell structure nanocomposites. [Copyright &y& Elsevier]

Abstract: TiO2/CoFe2O4 composite nanoparticles with a core–shell structure have been obtained. The core CoFe2O4 nanoparticles were synthesized via co-precipitation method, and the shell TiO2 nanocrystals were derived via sol–gel technology followed by heat-treatment at 450 °C. The morphology and the crystalline structure of composite nanoparticles were characterized by transmission electron microscopy (TEM) and X-ray diffraction, respectively. The as-prepared composite particles can be utilized as a magnetic photocatalyst, which can be fluidized and recovered by an applied magnetic field enhancing both the separation and mixing efficiency for recyclable fluids. Magnetic properties and photocatalytic activities of these powders have been evaluated. [Copyright &y& Elsevier]

Abstract: The spherical nickel nanoparticles (an average diameter of 75nm) were prepared by wire electrical explosion method, and silica was coated on nickel forming complete coverage by the controlled hydrolysis and condensation of tetraethyl orthosilicate (TEOS). The method was based on the use of silane coupling agent 3-mercaptopropyltrimethoxysilane (HS-(CH2)3Si(OCH3)3, MPTS) as a primer to render the nickel surface vitreophilic, thus rendering nickel surface compatible with silica. The thickness of SiO2 coating layer increases with the increasing reaction time. The nickel nanoparticles and the nickel coated with silica shell were confirmed by transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) was used to gain insight into the way in which the MPTS is bound to surface of the nickel nanoparticles. Result of the thermogravimetric analysis (TGA) and differential thermal analysis (DTA) indicate that the thermal stability of nickel/silica is better than of pure nickel nanoparticles. Magnetic properties of these powders have been evaluated. These nickel/silica core–shell nanoparticles can be utilized as precursors for making property-tunable magnetic nanoparticles, thin films, and multilayered core–shell structure nanocomposites. [Copyright &y& Elsevier]

Abstract: In this work, 3D SnO2 with a hierarchical structure, which was built by numerous one-dimensional tetragonal prism nanorods, had been firstly synthesized by a facile one-step hydrothermal route at 200°C in the presence of cetyltrimethylammonium bromide (CTAB). The cationic surfactant CTAB played a key role in forming the 3D SnO2 hierarchical structure composed of nanorods. In addition, the novel SnO2 hierarchical structure exhibited good gas-sensing properties. The gas sensor showed good selectivity to ethanol gas. Moreover, a linear dependence of the sensitivity on the ethanol concentration was observed, it suggested that the sensor fabricated by SnO2 hierarchical structures is very suitable to detect ethanol with low concentration. [Copyright &y& Elsevier]