In vivo evaluation of cerium,gallium and vanadium-doped borate-based bioactive glass scaffolds using rat subcutaneous implantation model

The main objective of this study was to evaluate the cerium, gallium and vanadium-containing bioactive borate glass scaffolds for soft tissue applications and determine the potential toxicity of these scaffolds on the adjacent tissues. The effects of the cerium, gallium and vanadium substitution on the soft tissue ingrowth and angiogenesis in porous borate based bioactive glass scaffolds were investigated using rat subcutaneous implantation model. For this purpose, bioactive borate glass powders containing therapeutic ions were prepared by melt-cast method and subsequently scaffolds were fabricated using polymer foam replication technique. The scaffolds were implanted subcutaneously for 4 weeks in Sprague Dawley rats. Bare borate glass scaffolds with the same microstructure were used as the control. Histology was used to evaluate tissue ingrowth and blood vessel formation in the implants. Additionally, the antibacterial activities of cerium, gallium and vanadium containing porous bioactive glass scaffolds were investigated in vitro by a zone inhibition method. Results revealed that addition of cerium ions to the borate glass network caused an increase in blood vessel formation. On the other hand, a decrease was obtained in angiogenesis in gallium and vanadium-containing glasses. All of the scaffolds prepared in the study did not show any antibacterial activity towards Escherichia coli and Staphylococcus aureus.     

Water-induced CsBr crystalline transition to CsPbBr3 and the change of luminescence properties in borophosphate glass

The application of all-inorganic perovskite CsPbBr₃ nanocrystal glasses recently has enjoyed increasing and diverse attention due to their excellent optical properties. However, a full understanding of their formation process and mechanism still remains uncharted. In an attempt to develop and improve the properties of these glasses, it is significant to explore the formation of CsPbBr₃ nanocrystals (NCs) in it. Herein, a borophosphate-based precursor glass with bright blue emission was prepared by melt quenching, and CsPbBr₃ NCs were precipitated in it by water induction; the glass powders’ photoluminescence gradually changed from blue to green (478–525 nm). It is proven that the blue luminescence originated from the combination of CsBr and oxygen vacancies in the glass, and the crystal transformation mechanism of CsBr to CsPbBr₃ in glass is proposed; the potential application in anti-counterfeiting is explored based on its special properties. The findings of this study are significant to the basic research for the CsPbBr₃ NCs glasses, and also contribute new insights toward their application in different fields.     

Study of Eu3+–Gd3+ co-doped Ba–Bi–B glasses for red-laser applications: Physical,structural, photoluminescence and time-resolved spectral characteristics

A series of Eu³⁺ and Eu³⁺/Gd³⁺ co-doped barium-bismuth-borate (Ba–Bi–B) glasses were prepared by melt-quench technique. And deliberated the physical, structural, and spectroscopic properties of all glasses and explored the energy transfer process from Gd³⁺ to Eu³⁺ ions. The density of glasses increased with increasing of Gd³⁺ concentration in co-doped glasses. Characteristics of steady-state and time-resolved photoluminescence (PL) of Eu-doped and Eu³⁺-Gd³⁺ co-doped glasses under different excitation wavelengths suggested the prospects of the investigated glass system for display device applications. PL spectrum displays a strong red emission peak centered at 612 nm due to the Eu³⁺: ⁵D₀→ ⁷F₂ transition. Less intense emissions centered at 577 nm (⁷F₀), 590 nm (⁷F₁), 651 nm (⁷F₃) and 700 nm (⁷F₄) are also observed from the radiative transitions of the excited state ⁵D₀ of Eu³⁺ions. The values of radiative parameters such as transition probability, branching ratios, and stimulated emission cross-sections were obtained from Judd–Ofelt theory analysis and indicated the aptness of the Ba–Bi–B glasses for optical devices. A 5-fold enhancement in the PL intensity was observed in 1.0 mol% Eu³⁺ and 3.0 mol% Gd³⁺ co-doped glass under λ_Exci. = 394 nm excitation. The calculated commission Internationale de l'eclairage color coordinates and correlated color temperature values show that the Ba–Bi–B glasses are useful for red-laser and display device applications.     

WS2/bioactive glass composites: Fabrication,structural, mechanical and radiation attenuation properties

Ionizing radiation interaction might occur during diagnostic imaging and radiotherapy procedures. It has been reported that gamma-ray radiation can damage the living cells through the energy transfer. Therefore, investigation the ionization radiation attenuation properties of biomaterials have a crucial importance. In the current study, tungsten disulphide (WS₂) nanopowder-containing borate-based bioactive glass composites were prepared. Their physical, structural, mechanical and ionization radiation attenuation properties were investigated in detail. Monte Carlo simulations and radiation attenuation properties were studied through MCNPX and Phy-X/PSD. Results showed that sintering performed at 575 °C for 1 h in air atmosphere caused formation of some tungsten trioxide in the structure. Addition of WS₂ nanopowders increased the bulk density and improved the mechanical properties of the prepared bioactive glass composites. Simulation studies revealed the influence of WS₂ content on reduction the build-up factors and enhancement of the photon attenuation ability for all the considered photon energies.     

Effect of CeO2 on the Glass Structure of Sodium Germanate Glasses

Germanate glasses have potential applications as optical fibers. Materials doped with rare earth ions are good candidates for optical, lasing, and magnetic applications. Based on the ternary system, CeO₂–Na₂O–GeO₂ a series of six glasses were fabricated using powder fusion, and varying the Na₂O content from 0 to 45 mol%, and a CeO₂ content constant at 3 mol%. The glasses were analyzed by FT‐IR, Raman and X‐ray photoelectron (XPS) spectroscopies to obtain information about the glass structure, cerium oxidation's state and how it is introduced in the glass network. FT‐IR and Raman spectra revealed the presence of GeO₆ and GeO₄ groups as well as Q² and Q³ units in the glasses with alkali low content. XPS spectra analysis revealed that the cerium ions were reduced from Ce⁴⁺ to Ce³⁺. The nonbonding to total oxygen ratio was estimated from the curve fitting of the O 1s core level spectra. Density and elastic parameters showed a nonlineal tendency in the change of the physical properties as a function of Na₂O content. Finally, photoluminescence spectroscopy confirmed the presence of Ce³⁺ ions. The characteristic 4f → 5d electronic transitions at 360 nm were detected, when a 280 nm excitation line of pulsed laser was used as excitation source.     

Novel Visible Emission and Mechanism Investigation from PbS Nanoclusters‐Doped Borosilicate Glasses

Borosilicate glasses doped with PbO, ZnS, or PbS were fabricated to investigate the visible emissions (one located at 370 nm and another at 550 nm) observed in the PbO and ZnS codoped glass. Several series of glassy systems were designed to investigate the mechanism of above visible emissions. The absorption, photoluminescence (PL), photoluminescence excitation (PLE) spectra, and lifetime measurements were used to characterize all the emissions. The nanosecond level lifetimes for all the samples' 370 nm emissions ascribed the 370 nm emission to the glass defects. Measured lifetimes for the PbS quantum dots (QDs) in the glasses with an emission in the near‐infrared region which was about 8 μs was close to the values for the yellow emission, which confirmed the formation of PbS nanoclusters in the codoped glass was responsible for the yellow emission.     

Structural characterization and evaluation of antibacterial and angiogenic potential of gallium-containing melt-derived and gel-derived glasses from CaO-SiO2 system

Gallium-containing glasses were synthesized by the sol-gel and traditional melting techniques to obtain bioactive amorphous materials with antibacterial and angiogenic properties. The influence of gallium ion addition on glass structure was described using two spectroscopic methods (FTIR and ²⁹Si MAS NMR). DSC (Differential Scanning Calorimetry) analysis revealed differences in thermal properties, which were explained by varying ionicity of the chemical bonds. The study shows that gallium ions addition causes a significant difference in glass structure and, as a consequence, in thermal properties, microstructure, and biological response. Dissolution products of the researched glasses incubated in SBF and distillated water were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). To perform the indirect in vitro biocompatibility studies, human osteoblast-like cells (MG-63) were cultivated in the supernatants, which were obtained by incubation of the glass powders in the cell culture medium. The evaluation of the potential angiogenic properties of gallium-doped glasses was performed by measuring the release of human vascular endothelial growth factor (VEGF) from MG-63 cells. Dissolution products of the all samples were tested for antibacterial activity against gram-negative (E. coli) and gram-positive bacteria (S. aureus).     

Multifunctional carbon dots with high quantum yield for imaging and gene delivery

Carbon dots (CD) are luminescent nanomaterial with unique properties that show great potential in many applications. Herein, branched polyethyleneimine-based carbon dots (PCD) are prepared from branched polyethyleneimine by oxidation and a modified hydrothermal reaction. Structure and composition analysis indicate that obtained PCD possesses a 3–4 nm in diameter and a graphitic structure with lattice spacing of 0.30 nm. The PCD has a quantum yield of 54.3%. The bright photoluminescence shows that it can be used for cell imaging. The PCD exhibits extremely good biocompatibility and can be applied for gene delivery. Because of its specific nanostructure and photoluminescence property, the multifunctional PCD prepared shows potential for applications in bioimaging and gene delivery.     

生物活性玻璃多孔材料的制备及性能研究

采用溶胶-凝胶法制备生物活性玻璃58S及77S;通过熔融法制备生物活性玻璃45S5,分别向上述3种生物活性玻璃粉体以及它们的混合物中添加一定比例的造孔剂,通过一定的烧结工艺制成具有不同组成的生物活性多孔材料,利用体外实验方法结合DTA,SEM及FTIR等材料显微结构及性能研究手段分析比较了各种多孔材料的显微结构、表面形貌、抗折强度及生物活性.研究表明:58S和45S5混合制备的多孔材料是一种具有良好生物活性和生物矿化特性的生物材料,可用于制备骨缺损填充材料和骨组织工程支架.     

镓掺杂钒酸钇的制备及其发光性能

采用高温固相法合成钒基荧光材料YVO4:Ga3+,其最佳掺杂浓度是2%,最宜煅烧温度为1100℃。用XRD,SEM以及荧光光谱等手段对所合成的荧光粉进行了表征,结果表明,样品在近紫外光254nm激发下,产生位于350～700nm的宽带发射峰。其中,镓离子浓度逐渐增加到2%时,样品的荧光发射主峰由440nm平移到470nm。     

Hexagonal boron nitride as a new ultraviolet luminescent material and its application—Fluorescence properties of hBN single-crystal powder

Luminous properties of hexagonal boron nitride (hBN) single-crystal powder were studied by cathodoluminescence and photoluminescence spectroscopy. The single crystals grown by a high pressure and high temperature method showed typical excitonic spectra at peak wavelengths of 215, 220, and 227 nm at room temperature. Well-faceted hexagonal shaped single crystals exhibited the dominant 215-nm band. The 220- and 227-nm bands were singly or concurrently observed in the case of irregular-shaped crystal powders, though no discernible difference between the morphologies of crystal powders showing differently superimposed luminous spectral profiles of the 220- and 227-nm bands was observed. However, each band showed different spectral and decay features at 8 K, implying that the origins of the two bands are different.     

Conversion of Valence State and Coordination State of Fe in Transparent Glass‐Ceramics Containing Li2ZnSiO4 Nanocrystals

Transparent glass‐ceramics containing Li₂ZnSiO₄:Fe nanocrystals were prepared by melt‐quenching method followed by post‐heat‐treatment process. The as‐prepared glasses and glass‐ceramics showed red to near‐infrared photoluminescence centered at 730 nm, ascribed to Fe³⁺ ions in tetrahedral coordination. The intensity of the photoluminescence was enhanced by two technologically simple techniques—the valence state of irons was controlled from Fe²⁺ to Fe³⁺ ions using oxidizing agents, whereas the coordination state was compulsorily converted from octahedral to tetrahedral symmetry by performing a ceramization process. The presence of Fe²⁺ ions was considered a major origin for Fe³⁺ photoluminescence quenching. Oxidation of Fe²⁺ and conversion of Fe²⁺ ions into tetrahedral symmetry contribute to suppression of energy transfer from Fe³⁺ emitters to Fe²⁺ quenching centers.     

Photoluminescent carbon nanoparticles produced by confined combustion of aromatic compounds

We report new photoluminescent carbon nanoparticles having an average particle size of 50 nm. When dispersed in chloroform and excited with 325 nm wavelength, the solution showed strong photoluminescence at 475 nm with 12–13% quantum yield. A well dispersed photoluminescent solution can also be prepared with ethanol, xylene or hexane using the nanoparticles. The nanoparticles were prepared by a simple confined combustion of an aromatic compound such as benzene, toluene, xylene or a mixture thereof in air.     

Photoluminescence, γ-irradiation and X-ray induced luminescence studies of Sm3+-doped oxyfluorosilicate glasses and glass-ceramics

Sm³⁺-doped oxyfluorosilicate glasses were fabricated through traditional melt quenching technique. After the heat treatment of the prepared glass, transparent SrF₂ nanocrystalline glass-ceramics (GC) were obtained. The amorphous nature of the prepared glasses and crystalline phase (SrF₂) of the GC were confirmed by XRD analysis. Abbe number was calculated for all the prepared glasses by measuring refractive index at different wavelengths. In the framework of Judd-Ofelt (JO) theory, the JO intensity parameters were obtained from the absorption spectra of 1.0 mol% Sm₂O₃-doped glass. The photoluminescence spectrum was recorded with 401 nm excitation. From the analysis of optical spectra and JO parameters, the radiative properties like radiative transition probabilities, branching ratios and radiative lifetimes for the fluorescent levels of Sm³⁺ ions were determined. The effect of γ-irradiation on luminescence properties and X-ray induced luminescence properties were also studied. The emission intensity was increased for GC where as it decreases with increase of γ-irradiation dosages. There are no noticeable changes in the position as well as intensity in photoluminescence and X-ray induced luminescence spectra for GC sample but after the γ-irradiation, the emission intensity was decreased moderately. The luminescence decay profiles for ⁴G_5/2 level were recorded and it is changed from exponential to non-exponential nature for higher Sm³⁺ ion concentrations. The decay profiles which exhibit non-exponential nature are well fitted to the Inokuti-Hirayama model and determined the energy transfer parameters. By using the integrating sphere, the quantum yield values were obtained for all the prepared glasses. The detailed study of the present glasses reveals that these glasses could be useful for radiation shielding and scintillation applications.     

Synthesis,Characterization, and In Vitro Bioactivity of Sol‐Gel‐Derived Zn,Mg, and Zn‐Mg Co‐Doped Bioactive Glasses

Bioactive glasses in the systems CaO‐SiO₂‐P₂O₅‐ZnO, CaO‐SiO₂‐P₂O₅‐MgO, and CaO‐SiO₂‐P₂O₅‐MgO‐ZnO were prepared and characterized. Bioactive glass powders were produced by the sol‐gel method. The prepared bioactive glass powders were immersed in a simulated body fluid (SBF) for periods of up to 28 days at 310 K to investigate the bioactivity of the produced samples. Inductively coupled plasma (ICP) and ultraviolet (UV) spectroscopic techniques were used to detect changes in the SBF composition. X‐Ray diffraction (XRD) was utilized to recognize and confirm the formation of a hydroxyapatite (HA) layer on the bioactive glass powders. Microstructural characterizations of the bioactive glass samples were investigated by scanning electron microscopy (SEM) techniques. Density, porosity, and surface area values of bioactive glass powders were also determined in order to characterize the textural properties of the samples. The results revealed the growth of an HA layer on the surface of the bioactive glass samples. MgO in the glass sample increases the rate of formation of an HA layer while ZnO in the glass slows it down.     

The role of the stabilizing agent on the structural and luminescent properties of hydrothermally synthesized ZrO2:Tb3+phosphors

Zirconium oxide powders doped with terbium, synthesized by hydrothermal route from a highly basic solution, were used to determine the role of the basic agent (NaOH, KOH or LiOH) utilized to carry out the hydrothermal synthesis on their morphology, crystalline structure, photoluminescent or cathodoluminescent properties. The synthesized powders showed an amorphous/polycrystalline nature with tetragonal phase crystallites of ZrO₂. The ratio of material undergoing the transformation from amorphous to crystalline is highly influenced by the kind of stabilizing agent used. As for the photoluminescence (PL) and cathodoluminescence (CL) results, the samples present the characteristic emission lines corresponding to inter electronic energy levels transitions for Tb³⁺ ions (⁵D₄ → ⁷F_J (J?=?3–6) transitions). The photoluminescence excitation spectra present a broad peak centered at 250?nm for all samples, however the sample prepared with LiOH as basic agent presented an additional peak at 290?nm which much likely is related to localized centers introduced by Li⁺ ions into the ZrO₂ crystallites.     

Bioactive assessment of bioactive glass nanostructures synthesized using synthetic and natural silica resources

The sol-gel route of synthesizing bioactive glasses of composition 45S5 has shown higher compatibility than the melt casting method. In bioactive glass synthesis, a major silica source is derived from the synthetic tetraethyl orthosilicate precursor. This work demonstrates the sol–gel-derived bioactive glass prepared from rice husk and TEOS as silica sources. In this study, the effect of crystallization with respect to the silica source in bioactive glass composition was investigated to gain further understanding on the processes involved in the fabrication of bioglass. The in vitro biodegradation and apatite formation of the bioactive glass in simulated body fluid was investigated by spectroscopic and morphological studies. Both the bioactive glasses show a change in morphology toward nanostructured apatite formation after in vitro immersion studies. Further, the hemocompatibility of bioactive glass prepared using rice husk is similar to bioactive glass prepared from organic silica sources. This promises the possibility of synthesizing low cost and biocompatible bioactive glass 45S5 system for tissue engineering applications.     

Nanostructured cerium oxide: preparation and properties of weakly-agglomerated powders

Nanocrystalline powders of cerium oxide were prepared from cerium(III) nitrate solution by a two-stage precipitation process which yielded weakly-agglomerated powders with a crystallite size smaller than 5 nm. Hydrogen peroxide was added to cerium nitrate at 5°C to slowly oxidise Ce³⁺ to Ce⁴⁺ and thereby initiate homogeneous precipitation with the formation of dense spherical agglomerates. The precipitation process was completed by the addition of ammonium hydroxide which disrupted the spherical agglomerates leaving a weakly-agglomerated power of hydrated ceria. The process was completed by hydrothermal treatment at 180°C without increase in crystallite size. The powders were characterised by X-ray diffraction, transmission electron microscopy and thermogravimetric analysis. The weakly-agglomerated state of the powder and the uniform crystallite size of under 5 nm are favourable characteristics for many applications.     

Influence of glass composition on photoluminescence from Ge2+ or Ag nano-cluster in germanate glasses for white light-emitting diodes

Germanium glass has attracted much interest because of its potential application as the optical waveguides and communication devices. In this work, germanium glass was prepared, exhibiting the blue luminescence at the 410 nm from the Ge²⁺. The influence of SiO₂ addition in the germanate glass on the 410 nm luminescence of the Ge²⁺ was observed. The SiO₂ addition promoted the formation of Ge²⁺, which is because the Si⁴⁺ ions can deprive the O²⁻ ions from the Ge⁴⁺ ion caused by the lower optical basicity of Si⁴⁺ ions than Ge⁴⁺ ion. The germanium glasses containing the Ag nano-clusters were prepared using ion-exchange method. The influence of SiO₂ concentration on the size of Ag nano-clusters was observed, which stabilize the size distribution and lead to the miniaturization of Ag nano-clusters. The Ag nano-clusters size dependence of their photoluminescence was observed in germanate glasses, and the tunable photoluminescence of Ag nano-clusters was obtained by controlling the size of Ag nano-clusters. It is noticed that the Ag nano-clusters formed in the germanate glass showed the white light emission characteristic excited at the blue chip, exhibiting the practical application as the blue converted white light-emitting diodes.     

Structure,Judd-Ofelt analysis and spectra studies of Sm3+-doped MO-ZnO-B2O3–P2O5 (M = Mg,Ca, Sr,Ba) glasses for reddish-orange light application

In the present work, a series of Sm³⁺-doped MO-ZnO-B₂O₃–P₂O₅ (M = Mg, Ca, Sr, Ba) glasses were prepared. The glass structure and luminescence properties were investigated by XRD, DSC, IR, absorption spectroscopy, Judd-Ofelt theory and photoluminescence spectra. The J-O parameters of Sm³⁺-doped glasses follow the trend of Ω₄＞Ω₆＞Ω₂. Under the excitation of 401 nm Xenon lamp, Sm³⁺-doped glasses exhibited four emissions from the transitions of ⁴G_5/2→⁶H_J/2 (J = 5, 7, 9, 11) in the visible spectra. The luminous intensity of Sm³⁺ increases with the asymmetry in local environments and decreases with the increasing radius of the alkaline-earth cation. Among the as-prepared glass, the Sm³⁺-doped glass containing magnesium oxide exhibits higher values of stimulated emission cross-section (2.18 × 10⁻²¹ cm²), gain bandwidth (1.40 × 10⁻²⁷ cm³), and optical gain (3.83 × 10⁻²⁴ cm²). All the Sm³⁺-doped glasses show intense orange light in the CIE 1931 chromaticity diagram with a high color purity exceeding 99%. In addition, the time-resolved emission spectra reveal the decay process of the Sm³⁺ ions for the transitions ⁴G_5/2 → ⁶H_7/2 and ⁴G_5/2 → ⁶H_9/2 in the glass containing magnesium oxide. It suggests that Sm³⁺-doped alkaline-earth zinc borophosphate glasses could be a potential candidate for reddish-orange light-conversion fluorescent materials based on the ultraviolet light-emitting diode.