Amorphous Silicate Glass Research Articles

Comprehensive assessment of SrO and CuO co-incorporated 50S6P amorphous silicate bioactive glasses in vitro: Revealing bioactivity properties of bone graft biomaterial for bone tissue engineering applications

Bioactivity is critically important for a glass material to be used in bone tissue engineering, which is stated to be affected by the addition of therapeutic ions such as Sr and Cu. In this study, the findings of a comprehensive in vitro study on the bioactivity of previously produced and characterized in terms of structure, composition and thermal features novel SrO and CuO co-incorporated 50S6P (SiO2–CaO–Na2O–P2O5, SrO–CuO) glasses were discussed. Herein, chemical bond, morphology, composition, and crystallinity changes on the amorphous silicate glasses were investigated using FT-IR, SEM-EDX, and XRD analysis, respectively. Furthermore, quantitative assessment of glass ionic dissolution products concentrations were performed in contact with simulated body fluid by ICP-OES analysis. SrO and CuO co-incorporated 50S6P amorphous silicate glasses showed an appropriate release profile in terms of its ionic products (Si4+: 18.5–32.6, Ca2+: 132.1–234.3, Sr2+: 1.29–2.35, Cu2+: 2.28–3.34, ppm), which resulted in the formation of Ca–P layer and the proceeding of its accumulation, further conformed with FT-IR and SEM-EDX. Furthermore, apatite layer, which consists of crystal apatite ranging in size (6.5–9.8 nm) having different degree of crystallinity percentages (2.5–22.4%), was formed on the glasses surface within 28 days in SBF. The results revealed that Sr incorporation (4.22 wt %) has an enhancing effect on bioactivity, whereas increased Cu incorporation (0.10–0.26 wt %) had a relatively inhibitory effect on bioactivity of the glasses. These findings are indicators of desirable bioactive features of 50S6P glasses. Thus, these bioactive glasses are acceptable to be utilized in bone tissue engineering application as bone graft biomaterials.

Evaluation of novel composition (SiO2–CaO–Na2O–P2O5, SrO–CuO) degradable amorphous silicate glasses properties and comprehensive characterization of the thermal features

The current work presents and discusses the findings of a comprehensive study on the structural, chemical and thermal properties of SrO and CuO incorporated SiO2–CaO–Na2O–P2O5 amorphous silicate glass with a novel composition. Here, fundamental features (experimental density, oxygen density, and hardness) of all glasses were determined and chemical as well as phase composition of the glasses was verified with XRF and XRD, respectively. Moreover, the thermal behavior (viscos flow and crystallization kinetics) of amorphous silicate glass was investigated by non-isothermal methods using DTA analysis. The activation energies of glass transition (Eg) were calculated in the range of 546–1115 kJ/mol by Kissinger method, whereas the activation energies of crystallization (Ec) were calculated in the range of 164–270 kJ/mol by three different methods (Kissinger, Ozawa, Yinnon and Uhlmann). Avrami exponent (n) values ranged from 1.17 to 3.28 demonstrated that amorphous silicate glasses have different crystallization mechanism. Working temperature, which is one of the parameters indicating glass stability, increased with the incorporation of Sr and Cu from 187 °C to 245 °C. The initial dissolution measurement has been applied to study the degradability behavior of Sr and Cu incorporated amorphous glasses in vitro. Quantitative evaluation of Si4+ (0.156–0.373 kV), Ca2+ (0.043–0.332 kV), Na+ (0.044–0.329 kV), P5+ (0.057–0.289 kV), Sr2+ (0.134–0.385 kV), and Cu2+ (0.090–0.203 kV) depending on the ion activation energy (Ea-ion) and ion concentration at different temperature values (24, 37 and 55 °C) was performed in contact with Tris-HCl solution by ICP-OES analysis. The results revealed that investigated glasses were degradable and incorporation of Sr and Cu affected the glass initial dissolution. Overall, investigated glasses are suitable for various application such as hot-working production, glass-ceramic manufacturing, and glass or glass-ceramic scaffolds fabrication, due to wide working temperature ranges and high crystallization tendencies of the developed glasses.

МОЛЕКУЛЯРНО-ДИНАМИЧЕСКОЕ МОДЕЛИРОВАНИЕ СТРУКТУРЫ И СВОЙСТВ СТЕКЛООБРАЗНОЙ ПОДЛОЖКИ SiO2 В ШИРОКОМ ДИАПАЗОНЕ ТЕМПЕРАТУР

F.V. Grigoriev's paper “Force Fields for Molecular-Dynamic Modeling of Sputter Deposition Process on Silicon Dioxide Film”, proposes a simple DESIL inter-ion potential for modeling amorphous SiO2 substrates widely used for thin film sputter deposition. This potential provides an important advantage when compared with popular potential of BKS due to the absence of a non-physical attraction region at short distances between particles. This is important when simulating SiO2 substrate sputtering where collisions between particles result in short-range proximity. In this case an artifact of particle inter-capture may be observed which distorts the simulation results. The purpose of this work is to demonstrate the potential for predicting the structural and thermodynamic characteristics of amorphous silicate glasses over a broad temperature range.

A comprehensive study on copper incorporated bio-glass matrix for its potential antimicrobial applications

In this study, sol-gel derived Cu substituted 70S bioglass (70SiO2-(20-x) CaO–10P2O5-xCuO; where x = 0, 0.5, 1, 1.5) were synthesized as a new multifunctional bioactive glasses (BGs). The effect of Cu substitution in the bio-glass matrix was evaluated for its impact on pathogen (Escherichia coli and Staphylococcus aurous). Fourier Transform Infrared spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), X-Ray Diffraction (XRD), Inductively Coupled Plasma spectroscopy (ICP) and Scanning Electron Microscopy (SEM) revealed that the obtained powders are amorphous silicate glass. The substituted element is present in the desired molar concentration. In vitro bioactivity test was performed in SBF solution by immersion of bioglass pellets. Antibacterial test was carried out against Escherichia coli and Staphylococcus aureus. The results showed that the prepared BGs have a high acellular bioactivity observed by a fast formation of thick and continuous layer of carbonated hydroxyapatite (CHA). The antibacterial properties of the substituted bio-glass matrix was indicated by the growth inhibition of bacterial colonies. The obtained results showed that copper substituted bio-glass is having potential to avoid post-surgical infections and it also represents the capability of hard tissue regeneration.

Theoretical and experimental characterization of Cu-doped amorphous silicate glass

The coordinative environment of Cu2+ ions incorporated in oxide glasses has been intensively studied for glasses doped with copper ions by melting or ion exchange. Much less is known about their coordination in a sol-gel derived silicate glass. Mesoporous silicate glasses doped with copper (II) ions coming from four different salts were synthesized by the acid-catalyzed sol-gel method. The electronic and structural states of copper sites were probed by optical and X-ray spectroscopies. The experimental observations were confronted with the results of quantum-chemical calculations. The theoretical models consisted of four- and five-coordinated Cu2+-complexes, where water ligands were sequently replaced with the SiO44‒ tetrahedra. The best agreement between the experimental and theoretical electronic spectra has been reached for the four-coordinated Cu2+-complex with a water molecule and three or four SiO44‒ tetrahedra. The energy band gap intervals of 4.21–4.61 eV and 4.09–4.23 eV were estimated graphically by the TAUC plot method and from quantum-chemical modelling, respectively.

Новый подход к формированию органо-неорганических борсилоксановых полимерных структур

Using sol-gel methods, new synthetic approaches to the preparation of boron-containing organic-inorganic hybrid polymers based on boron oxide (boric anhydride), which is a part of many inorganic materials, have been developed. Previously, such methods were used to obtain amorphous silicate glasses and their use allows introducing various inorganic and organic modifiers into the matrix of silicon dioxide and other compounds at temperatures up to 120 °C. Within the framework of this work: a) the conditions for obtaining saturated solutions of boron oxide in organic solvents were found and it was found that boric anhydride is most completely dissolved in triethyl orthoformiate (approximately 25%) at 110-110 °C retaining its structure; b) by the condensation of boric acid with 1,3-dichlorotetraphenyl disiloxane, functional borcyclosiloxanes were synthesized to further modify boron oxide. The reaction conditions, spectral and thermal characteristics of condensation products were investigated. It is shown the increasing in the synthesis time to 15-18 h, a bicyclic borsiloxane is formed; c) homophasic modification of boric anhydride with monofunctional cyclic borsiloxanes was carried out and it was shown that the formation of Si-O-B bonds at 110-120 °C occurs due to the use of anhydrous sol-gel process. Transparent films are obtained from modified boric anhydride solutions deposited on glass and stainless steel, followed by curing at a temperature of 160-280 °C, that are not subjected to hydrolysis under the action of air moisture and are stable in air up to 600 °C. As a result of the work, the possibility of obtaining a borsiloxane type polymeric structures having an inorganic molecular skeleton modified with organosilicon compounds has been investigated.

Experimental exploration of the hydrodynamic effect polishing machinability for different types of material

Hydrodynamic effect polishing (HEP), in which the material removal relies on the chemisorption between nanoparticles and the workpiece surface in elastic mode, can realize automatic level smooth surface without surface/subsurface damage. The machinability of different types of optical material (such as monocrystalline silicon and crystalline quartz, amorphous silicate glass, Zerodur and so on) were investigated experimentally. The workpiece surfaces before and after being polished by HEP was observed by atomic force microscopy. The experimental results show the surface roughness of monocrystalline silicon and quartz, amorphous silicate glass have decreased from Rms 0.737nm to Rms 0.175nm, Rms 0.490nm to Rms 0.187nm, Rms 0.469nm to Rms 0.157nm respectively, and meanwhile all the defects and bumpy structures have been removed clearly. However the surface roughness has increased from Rms 0.213nm to Rms 0.321nm with the obvious increment of micro unevenness. By comparison, we can conclude that excellent performance is shown when HEP is applied on the optical material structure with a single monocrystalline or amorphous component. However the ultrasmooth surface cannot be obtained when HEP was applied on the combinational materials such as Zerodur glass. The micro unevenness increases gradually along with polishing process due to the different material removal of the monocrystalline and amorphous component.

Atomic scale imaging of amorphous silicate glass surfaces by scanning force microscopy

The determination of the atomic structure of amorphous materials with conventional diffraction techniques is hindered by the missing periodicity of the samples. Consequently, a deeper insight into the structural properties of glasses can only be obtained in real space. In this work AFM investigations of silicate glass surfaces, namely fresh barium silicate and silica glass fracture surfaces, are described. The observed atomic-scale features and arrangements are compared with each other as well as with results from other methods and discussed in the context of classical glass structure theories. The results clearly demonstrate that AFM is able to provide atomically resolved surface structures of amorphous glass surfaces.

The shear strength of a shocked borosilicate glass with an internal interface

The shock properties of amorphous silicate glasses, under conditions of one-dimensional strain, have been of interest for a number of years. In the past decade, attention has focused on the shock-induced fracture of these materials, in particular the failure wave. This was first observed by Razorenov et al., from rear surface velocity traces in K19 glass (similar to soda-lime). They noticed a small increase in velocity superimposed on these traces, and interpreted it as the result of the release from the rear surface of the target being partially reflected by a moving front (the failure wave) within the material. As this reflection was recorded as a reload, they concluded that the material behind this front must have undergone a reduction in shock impedance. This led them to suggest that the material had fractured. Several years earlier, Nikolaevski had proposed just such a mechanism for the dynamic failure of brittle solids. Brar et al. also observed this front, using spall strength and lateral stress measurements. Spall strengths were seen to be high ahead of this front, but diminished to zero behind it. They also observed an increase in lateral stress, sometime after the arrival of the main shock. Since the shearmore » strength ({tau}) of any material under one-dimensional shock loading, is expressed as, 2{tau} = {sigma}{sub x} {minus} {sigma}{sub y}, where {sigma}{sub x} and {sigma}{sub y} are the longitudinal and lateral components of stress respectively, it was clear that the material was undergoing a significant reduction in shear strength behind the failure wave. Bourne et al. were also able to observe this moving front in both soda-lime and borosilicate glasses as a loss of opacity, using high-speed photography.« less