Phosphate-based Bioactive Glasses Research Articles

Development of a ReaxFF reactive force field for ternary phosphate-based bioactive glasses.

Phosphate-based glasses (PBGs) in the CaO-Na2O-P2O5 system have diverse applications as biomaterials due to their unique dissolution properties. A reactive force field (ReaxFF) has been developed to simulate these materials at the atomic level. The ReaxFF parameters of PBGs, including the interaction between phosphorus and calcium atoms, have been developed using a published code based on genetic algorithms. The training data, including the atomic charges, atomic forces, bond and angle parameters, and different differential energies, are chosen and measured from static quantum-mechanical calculations and abinitio molecular dynamics of PBGs. We did different short- and medium-range structural analyses on the bulk simulated PBGs with different compositions to validate the developed potential. Radial and angular distribution functions and coordination numbers of network formers and modifiers, as well as the network connectivity of the glass, are in agreement with experimental and previous simulations using both shell-model classical force fields and abinitio simulated data; for example, the coordination number of phosphorus is 4.0. This successful development of ReaxFF parameters being able to describe the bulk PBGs enables us to work on the dissolution behavior of the glasses, including the interaction of water molecules with PBGs, in future works.

Advanced Bioactive Glasses: The Newest Achievements and Breakthroughs in the Area.

Bioactive glasses (BGs) are especially useful materials in soft and bone tissue engineering and even in dentistry. They can be the solution to many medical problems, and they have a huge role in the healing processes of bone fractures. Interestingly, they can also promote skin regeneration and wound healing. Bioactive glasses are able to attach to the bone tissues and form an apatite layer which further initiates the biomineralization process. The formed intermediate apatite layer makes a connection between the hard tissue and the bioactive glass material which results in faster healing without any complications or side effects. This review paper summarizes the most recent advancement in the preparation of diverse types of BGs, such as silicate-, borate- and phosphate-based bioactive glasses. We discuss their physical, chemical, and mechanical properties detailing how they affect their biological performances. In order to get a deeper insight into the state-of-the-art in this area, we also consider their medical applications, such as bone regeneration, wound care, and dental/bone implant coatings.

Independent and complementary bio-functional effects of CuO and Ga2O3 incorporated as therapeutic agents in silica- and phosphate-based bioactive glasses

The incorporation of therapeutic-capable ions into bioactive glasses (BGs), either based on silica (SBGs) or phosphate (PBGs), is currently envisaged as a proficient path for facilitating bone regeneration. In conjunction with this view, the single and complementary structural and bio-functional roles of CuO and Ga2O3 (in the 2–5 mol% range) were assessed, by deriving a series of SBG and PBG formulations starting from the parent glass systems, FastOs®BG – 38.5SiO2—36.1CaO—5.6P2O5—19.2MgO—0.6CaF2, and 50.0P2O5—35.0CaO—10.0Na2O—5.0 Fe2O3 (mol%), respectively, using the process of melt-quenching. The inter-linked physico-chemistry – biological response of BGs was assessed in search of bio-functional triggers. Further light was shed on the structural role – as network former or modifier – of Cu and Ga, immersed in SBG and PBG matrices. The preliminary biological performance was surveyed in vitro by quantification of Cu and Ga ion release under homeostatic conditions, cytocompatibility assays (in fibroblast cell cultures) and antibacterial tests (against Staphylococcus aureus). The similar (Cu) and dissimilar (Ga) structural roles in the SBG and PBG vitreous networks governed their release. Namely, Cu ions were leached in similar concentrations (ranging from 10–35 ppm and 50–110 ppm at BG doses of 5 and 50 mg/mL, respectively) for both type of BGs, while the release of Ga ions was 1–2 orders of magnitude lower in the case of SBGs (i.e., 0.2–6 ppm) compared to PBGs (i.e., 9–135 ppm). This was attributed to the network modifier role of Cu in both types of BGs, and conversely, to the network former (SBGs) and network modifier (PBGs) roles of Ga. All glasses were cytocompatible at a dose of 5 mg/mL, while at the same concentration the antimicrobial efficiency was found to be accentuated by the coupled release of Cu and Ga ions from SBG. By collective assessment, the most prominent candidate material for the further development of implant coatings and bone graft substitutes was delineated as the 38.5SiO2—34.1CaO—5.6P2O5—16.2MgO—0.6CaF2—2.0CuO—3.0Ga2O3 (mol%) SBG system, which yielded moderate Cu and Ga ion release, excellent cytocompatibility and marked antibacterial efficacy.

FTIR Spectral Characterization, Mechanical Properties and Antimicrobial Properties of La-Doped Phosphate-Based Bioactive Glasses

(Na2O)0.20(CaO)0.14(P2O5)0.66−x(La2O3)x, where x = 0, 0.1, 0.3, 0.7 and 1 wt.%, was prepared by the conventional melt-quenching method. Physical and mechanical properties such as density, Vickers microhardness, compressive strength and fracture toughness were measured for all prepared glass samples. In order to evaluate in-vitro bioactivity of the prepared glasses, sample powders (particle size range 106-180 μ m) were soaked in simulated body fluid (SBF) solution at 37 ± 0.5∘C for 7, 14 and 21 days. Then, soaked samples were investigated by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) technique and transmission electron microscopy (TEM). Furthermore, the antimicrobial activity of these glasses was tested against E. coli, S. aureus, B. cereus, B. subtilis and C. albicans by the disc-diffusion method. The obtained results indicated that significant increases in density, mechanical properties and antibacterial activity against S. aureus and E. coli bacteria were obtained as the La content increases. XRD and FTIR spectra revealed that the bioactivity of the prepared glasses was not affected by increasing of the La content. These results suggested that these glasses can be extensively used in various biomedical applications.

Structures and properties of phosphate-based bioactive glasses from computer simulation: a review.

Phosphate-based bioactive glasses (PBGs) dissolve harmlessly in the body with a dissolution rate which depends sensitively on composition. This makes them proposed vectors for e.g. drug delivery, or other applications where an active component needs to be delivered at a therapeutically appropriate rate. Molecular dynamics (MD) simulations provide atomic-level structural information about PBG compositions. We review recent work to show that MD is an excellent tool to unravel the connections between the PBG glass composition, its atomic structure, and its dissolution rate, which can help to optimise PBGs for specific medical applications.

Surface functionalization of phosphate-based bioactive glasses with 3-aminopropyltriethoxysilane (APTS)

AbstractThe effect of SrO substitution for CaO, in the 50P

Ab initio molecular dynamics simulations of structural changes associated with the incorporation of fluorine in bioactive phosphate glasses

Phosphate-based bioactive glasses containing fluoride ions offer the potential of a biomaterial which combines the bioactive properties of the phosphate glass and the protection from dental caries by fluoride. We conduct accurate first-principles molecular dynamics simulations of two compositions of fluorinated phosphate-based glass to assess its suitability as a biomaterial. There is a substantial amount of F–P bonding and as a result the glass network will be structurally homogeneous on medium-range length scales, without the inhomogeneities which reduce the bioactivity of other fluorinated bioactive glasses. We observe a decrease in the network connectivity with increasing F content, caused by the replacement of bridging oxygen atoms by non-bridging fluorine atoms, but this decrease is small and can be opposed by an increase in the phosphate content. We conclude that the structural changes caused by the incorporation of fluoride into phosphate-based glasses will not adversely affect their bioactivity, suggesting that fluorinated phosphate glasses offer a superior alternative to their silicate-based counterparts.

Influence Of Zro2 on The Physicochemical Properties of Phosphate-Based Glasses and Glass Ceramics

Phosphate-based bioactive glasses and their glass ceramics for 47P2O5– (30.5)CaO–(22.5 − x)Na2O–xZrO2 for different ZrO2 contents (x = 0, 1.5, 3.0, 4.5, and 6.0 mol%) were prepared through melt quenching and controlled heat treatment procedures. The amorphous nature of glasses and the presence of crystalline phases in glass ceramics were studied by means of X-ray diffraction (XRD) studies. The density, molar volume, ultrasonic velocities, attenuation, elastic constants, and microhardness of glass and glass ceramics were used to study the structural changes. The formation of hydroxyapatite layer on the surface of glasses and glass ceramics after immersion in simulated body fluid (SBF) was explored through XRD, Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) analyses. The results indicate that the added ZrO2 increases the crosslink density of glasses, resulting in network stability, and also induces the formation of an apatite layer on the surface of glasses. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

Luminescence properties of Eu 3+ ions in phosphate-based bioactive glasses

Eu 2O 3-doped phosphate-based bioactive glasses have been prepared by varying the calcium/potassium to phosphate ratio and their luminescence properties have been studied through absorption and emission spectra and decay rate analysis. Second and fourth rank crystal-field (CF) parameters and the CF strength parameters have been calculated by assuming the C 2V symmetry for Eu 3+ ions in the present glasses. Judd–Ofelt analysis has been used to derive radiative properties such as transition probabilities, branching ratios, radiative lifetimes and peak-stimulated emission cross-sections for 5D 0 → 7F J ( J = 0–4) transitions. The relative luminescence intensity ratio of 5D 0 → 7F 2 and 5D 0 → 7F 1 transitions has been evaluated to estimate the local site symmetry around Eu 3+ ions. The observed 5D 0 → 7F 0 transition for higher calcium content indicates two distinct sites for Eu 3+ ion. Decay rates for the 5D 0 level of Eu 3+ ions in these glasses have been measured by monitoring the 5D 0 → 7F 2 transition. The lifetimes of the 5D 0 level are found to decrease with increase in calcium contents.

Structure, solubility and bioactivity in TiO 2-doped phosphate-based bioglasses and glass–ceramics

Phosphate-based bioactive glasses in addition to TiO 2 ( x = 0–2.5 mol%) were prepared by melt quenching technique. Glass–ceramics were prepared by controlled two-step thermal treatment of the as-prepared phosphate bioglasses at their nucleation and crystallisation temperatures. X-ray diffraction (XRD) analysis was used to explore the amorphous and crystalline nature of materials. The presence of calcium phosphate crystals like NaPO 3, α, β-Ca 2P 2O 7, α,β-Ca 3(PO 4) 2 and Na 5Ti(PO 4) 3 plays a dominant role in glass–ceramics. The structural changes were analyzed by density and T g measurements. The degradation process in deionised water (DIW) was observed by pH and weight loss measurements. It was interesting to note that the highest solubility phosphate glasses become stiffer to degradation with increasing TiO 2 content. Addition of TiO 2 leads to densify the glass structure and interconnect the cross-linkages in the network. Chemical durability of glass–ceramics in DIW purely depends on the formed crystalline as well as the residual glassy phases. The formation of a biologically active layer on the surface of glasses and glass–ceramics were investigated by in vitro studies through XRD analysis.

Effect of particulate bioactive glasses on human macrophages and monocytes in vitro

Bioactive glasses, originally developed to promote tissue adhesion, are finding an increasing array of biomedical applications. The aim of the current study was to assess the ability of silicate- and zinc phosphate-based bioactive glasses to modulate the secretion of cytokines from activated human macrophages and monocytes. Human macrophages and monocytes were isolated and cultured on surfaces coated with a range of quantities of the bioactive glasses. Nontoxic concentrations of the glasses were selected and assessed further for their ability to modulate the secretion of tumor necrosis factor (TNF)-alpha, interleukin (IL)-10 and -6, in the presence or absence of the stimulant lipopolysaccharide. 45S5 glass produced a significant reduction to the amount of TNF-alpha (p<0.05) and IL-6 (p<0.01) secreted by stimulated cells compared with cells stimulated in the absence of bioactive glass. A significant reduction in IL-6 secretion was also observed with the other silicate- and zinc phosphate-based glasses tested. IL-10 secretion was increased (but not significantly) in presence of all glasses tested. TNF-alpha and IL-6 secretion from stimulated cells was lower in presence of the silicate glasses compared with the zinc phosphate glasses, indicating that this system of bioactive glass might be of clinical use in conditions associated with inflammation.