Amorphous Bioglass Research Articles

Nanocomposite films of polycaprolactone and amorphous/sintered wollastonite nanoparticles for potential biomedical applications

Precipitation of an apatite layer on the surface of bioactive materials is considered an important step in the bone healing procedure. Wollastonite (CaSiO3) bioglass has been recently employed as a bone replacement material and also, a carrier for targeted drug delivery. Regarding the impact of a material structure on its biological activity, to achieve the 100 % clinical success, realizing the material crystallinity and bone bonding potential can be important. Therefore, this study tried to prepare pure wollastonite (WS) nano-powders (<20 nm) via an easy and fast hydrothermal process. Different quantities (5, 10 and 15 wt%) of the amorphous and crystalline particles have been added to polycaprolactone (PCL) to obtain composite films via a simple solvent casting technique. The in-vitro bioactivity of the prepared particles as well as composite films was studied by placing the samples in the simulated body fluid (SBF) for 21 days. The physicochemical and microstructural properties of the products were then characterized by XRD, FTIR, FESEM, EDS and TEM. Moreover, the influence of the crystallinity on the bioactivity of the synthesized nanoparticles and also the obtained composite films was investigated for the first time. The results indicated that the amorphous bioglass and the surface of composite containing 15 wt% WS were completely covered by a thick bone-like apatite layer Therefore, these findings revealed that the prepared composite films composed of amorphous WS could be regarded as promising bioactive candidates for bone filling applications.

Digital light processing porous TPMS structural HA &amp; akermanite bioceramics with optimized performance for cancellous bone repair

In recent years, amorphous bioglass is used to improve the bioactivity of HA (Ca 10 (PO 4 ) 6 (OH) 2 ). Nevertheless, bioglass crystallizes and reacts with the matrix to form a complex phase composition during sintering, resulting in an unclear mechanism for tailoring the properties of HA bioceramics. In this work, TPMS structural HA ceramics fabricated by digital light processing (DLP) were doped by akermanite (Ca 2 MgSi 2 O 7 ) to better tailor the porosity, bioactivity and mechanical strength. After sintering above 1000 °C, Mg 2+ ions from akermanite substitute Ca 2+ ions in HA, leading to the decomposition of HA into β-TCP. This process increases the porosity of bioceramics. Additionally, liquid phases sintering caused by akermanite gives rise to the densification and enhancement of grain bonding, thereby reinforcing the mechanical strength of scaffolds. For in vitro bioactivity, as the content of akermanite increases from 0 wt% to 20 wt%, carbonated hydroxyapatite firstly deposits onto the surfaces of scaffolds and then disappears, because excessive Mg 2+ prevent the hydroxyapatite crystallization. Finally, bioceramics with 5 wt% and 10 wt% of akermanite and sintering at 1100 °C exhibit a high porosity of over 80% and an appropriate compressive strength of over 2 MPa, while achieving an enhanced in vitro bioactivity and good biocompatibility. After optimization, this kind of porous scaffolds can be well applied to the repair of cancellous bone defect.

Influence of composition of β-TCP and borate bioglass scaffolds on cell proliferation of adipose tissue-derived mesenchymal stem cells: osteogenic differentiation

Scaffolds with Schwarz D geometry based on triply periodic minimal surfaces (TPMS) were obtained by 3D printing with a biodegradable and bioactive paste (66.5% calcium phosphate with and without magnesium, 28.5% bioglass borate (BGBS), 3% attapulgite, and 2% water by weight). The osteogenic differentiation of mesenchymal stem cells (hMSC) was performed from human adipose tissue (ADSCs) in the presence of the scaffolds, which were characterized by degradability (International Organization for Standar ISO 10993—Part: 14), in vitro bioactivity by immersion tests in SBF arranged by Kokubo at different time intervals, cell proliferation, and osteogenic differentiation by alkaline phosphatase activity. Calcium phosphate is associated with β-tricalcium phosphate (β-TCP), in addition to amorphous Bioglass Borate. Scaffolds with calcium and magnesium phosphate (β-TCP/Mg) showed better degradability and bioactivity than scaffolds without Mg. Both scaffolds showed porosity and pore interconnectivity. Mesenchymal stem cells showed good adhesion and cell proliferation in contact with the scaffolds. Scaffolds doped with Mg were better promoters of cellular proliferation, additionally they did not show a cytotoxic effect. Differentiation of the osteogenic environment was verified by alkaline phosphatase activity.

Crystallization of discrete ZrO2 polymorph in the amorphous bioglass matrix comprising essential elements

The exceptional biocompatibility of bioglass in amorphous form is well-known; nevertheless, their crystallization to yield auxillary products during elevated heat treatments were considered as a major obstacle to retain specialized features. The excellent mechanical features of crystalline ZrO2 is deliberated as a primary choice in orthopaedic applications. The study aims to hold the well crystallized ZrO2 grains in amorphous bioglass matrix at elevated temperatures devoid of the crystallization of auxiliary products. The choice of elemental composition in bioglass to retain amorphous state in crystallized ZrO2 were explored. Preliminary investigation on the elements choice to design bioglass has been optimized followed by the specific formulation to integrate in ZrO2 component. Subsequently five different bioglass formulations with increment in the element concentrations has been designed and integrated in ZrO2 matrix. The characterization results ensured the impregnation of cubic ZrO2 (c-ZrO2) component in amorphous SiO2 matrix devoid of structural degradation until 1400 °C. The indentation tests accomplished better mechanical features of the resultant compositions that displayed good concurrence with the commercialized ZrO2 products.

Effect of bioglass addition on the properties of HA/BG composite films fabricated by pulsed laser deposition

In order to improve the osteoconduction of metallic implants, bioactive films are often coated on the implant surfaces. In this paper, hydroxyapatite (HA) and bioglass (BG) composite films on Ti alloy were fabricated by pulsed laser deposition, and the effect of bioglass addition on the film properties was analyzed. Results show that the composite films are composed of crystalline HA, β-TCP and amorphous bioglass. The addition of bioglass decreases the crystallinity of the whole film and increases the Ca/P and Si/Na atomic ratio change rate. However an appropriate addition of bioglass can increase the adhesion strength to substrate and induce the c-axis orientation growth of HA. The composite film with 20 wt% bioglass exhibits excellent osteoconduction and can be considered as a prospective competitor for bone implantology applications.

Electrophoretic deposition and characterization of composite chitosan-based coatings incorporating bioglass and sol-gel glass particles on the Ti-13Nb-13Zr alloy

Composite bioglass/chitosan and sol-gel glass/chitosan coatings were electrophoretically deposited (EPD) on a near-β Ti-13Nb-13Zr alloy. The influence of EPD parameters, such as chemical composition and suspension pH as well as potential difference and deposition time, on the uniformity of coatings has been studied. It was found that the pH value of the suspension and chemical composition have a significant impact on the electrokinetic properties of suspended chitosan molecules and glass particles, which in turn affect the deposition rate of EPD and the uniformity of as-deposited coatings. The thicknesses of the bioglass/chitosan and sol-gel glass/chitosan coatings were up to 2μm and 860nm, respectively. The microstructure of the coatings was characterized by scanning and transmission electron microscopy as well as X-ray diffractometry. The coating microstructure was composed of sol-gel glass particles or amorphous bioglass separate particles or agglomerates, homogeneously embedded in an amorphous chitosan matrix. The sol-gel particles consisted of hydroxyapatite (hp), CaSiO3 (tp) phases. The sol-gel glass/chitosan coating exhibited better adhesion to the titanium alloy substrate than the bioglass/chitosan coating. It was found that both types of coating improve the electrochemical corrosion resistance of the Ti-13Nb-13Zr alloy in Ringer's solution and are cytocompatible with osteoblast-like cells.

Influence of phosphate precursors on the structure, crystallization behaviour and bioactivity of sol–gel derived 45S5 bioglass

Sol–gel derived fully amorphous bioglass (BG_(NH4)2HPO4) with composition close to bioglass 45S5 has been prepared and characterized.

The effect of crystallization of bioactive bioglass 45S5 on apatite formation and degradation

ObjectiveAmorphous bioglass 45S5 has been used for many years as bone substitute material. Bioactive glasses are also suitable as coating materials for implants in order to improve the bone ongrowth behavior. We hypothesize that both the apatite formation on the surface and the chemical stability can be improved by crystallization of the bioglass. MethodsSynthesized amorphous bioglass 45S5 specimens as well as samples which were crystallized at 1000°C were stored in simulated body fluid for 1, 7, and 14 days. The respective apatite formation was gravimetrically determined and characterized by SEM and XRD analysis. Moreover, the degradation behavior was studied after storage in distilled water. ResultsThe weight of the crystallized samples decreased 6.3% less than that of the amorphous samples. Calcium silica and calcium carbonate layers were found on amorphous bioglass after 7 and 14 days. However, apatite formation was observed only on the crystallized 45S5 samples after storage. SignificanceWe conclude that the chemical resistance can be improved and, in parallel, a pronounced apatite formation on the surface of 45S5 can be obtained by controlled crystallization of the material for the particular test setup. Therefore, crystallized bioactive glasses should be considered to be promising coating material for dental implants.

Low temperature spark plasma sintering of 45S5 Bioglass®

45S5 Bioglass® powder has been densified at low temperatures using Spark Plasma Sintering (SPS). By employing SPS with pressures ranging from 70 to 300MPa, it was possible to achieve fully dense and completely amorphous 45S5 Bioglass® samples at temperatures as low as 500–550°C. By increasing the sintering temperature up to 600°C the dense samples crystallized to Na2CaSi2O6 phase rather than Na2Ca2Si3O9 which is usually achieved at higher temperature. Acellular in vitro test results in Simulated Body Fluid (SBF) revealed that SPSed samples sintered at 600°C resulted in faster formation of hydroxyapatite compared to pressureless sintered ones (1050°C), which were highly crystallized. Amorphous Bioglass® and/or Na2CaSi2O6 phase prepared by SPS could potentially produce Bioglass® composites with increased bioactivity.

&lt;i&gt;In Situ&lt;/i&gt; Synthesis and Characterization of β-Tricalcium Phosphate/Na Doped 58S Bioglass Composite by Sol-Gel Technique

In situ synthesis technique of β-tricalcium phosphate(β-TCP)/ Na-doped 58S bioglass composite powders were investigated. Firstly, the β-TCP ultra-micro powders are synthesized via wet chemical method. β-TCP/Na doped 58S bioglass composite powders were synthesized in situ by sol-gel technique, using tetraethyl orthosilicate(TEOS), triethyl phosphate(TEP), calcium nitrate tetrahydrate(Ca(NO3)2•4H2O), sodium nitrate(NaNO3) as starting materials. The composite powders were characterized by XRD, EDX and SEM. The bioactivity of the synthesized powders was analyzed by immersion studies in simulated body fluid (SBF). The results show that the composite powders are made up of good crystalline β-TCP and amorphous bioglass, and it was conformed that the material had good osteoproduction and bioactivities, that is an indication of bioactive potential in vivo. It is believed that the β-TCP/ Na-doped 58S bioglass (58SN) composite by sol-gel technique in situ could be a desirable biomaterial for preparing scaffold of bone tissue engineering.

Following bioactive glass behavior beyond melting temperature by thermal and optical methods

The thermal behavior of a well known bioactive glass, Bioglass®, is examined beyond its melting temperature as the crystallization and sintering of bioactive glass may influence its bioactivity and cellular reactions. Differential thermal analysis (DTA) followed by thermogravimetric analysis (TGA) was used to determine the glass transition (Tg), the crystallization (Tc), the melting (Tm) temperatures and the weight changes. The characterization of bioactive glass before and after the thermal treatment at different characteristic temperatures was accomplished with Fourier transform infrared spectroscopy (FTIR). All the phases, during the heating of the material until an exact temperature beyond its melting temperature were determined. A progressive increase of its crystallization degree was observed, during treatment up to 1200 °C. At this temperature a number of successive crystallizations and fusions take place. At higher temperatures the formation of amorphous Bioglass® with simultaneous appearance of new phases is observed, favouring the bioactivity that in glass-ceramics is influenced by the different phases present. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Analysis of apatite layers on glass-ceramic particulate using FTIR and FT-Raman spectroscopy.

A nucleation and crystallization schedule was adapted to produce 40% crystalline Bioglass ceramic particulates. These particles were placed in a dynamic environment in a simulated physiologic solution (SBF-9) for time periods ranging from 10 min to 7 days. Fourier transform Raman spectroscopy (FT-Raman) and infrared spectroscopy (FTIR) were used to analyze the apatite layer formation on the particulates. FTIR determined that amorphous apatite formation took place within 2 h, with the appearance of crystalline apatite in 14 h. The vibrational frequencies obtained through FT-Raman were equivalent to those obtained using FTIR. These analyses showed that a fully crystallized apatite layer was present on the particulate after 3 days of exposure in SBF solution. These findings are consistent with those associated with amorphous Bioglass particles.