Bioactive Glass Surface Research Articles

Development, characterisation, biocompatibility, and corrosion analysis of gadolinium and selenium doped bioactive glass surface coating for dental implants

Development, characterisation, biocompatibility, and corrosion analysis of gadolinium and selenium doped bioactive glass surface coating for dental implants

Bioresorption and Biomineralization of S53P4 Bioactive Glass in Neutral Tris Buffer and Citric Acid Solution.

In this study, S53P4 (53SiO2-23Na2O-20CaO-4P2O5) bioactive glass (BG) were prepared through a melt-milling process, and their bioresorption and biomineralization behavior was evaluated by in vitro dissolution under different solution conditions (neutral and acidic). The particle size of S53P4 BG was controlled by milling, and the in vitro dissolution evaluation was performed in tris buffer and citric acid solution for 21 days at 37 °C according to ISO 10993-14 (biological evaluation of medical devices). During dissolution, the ion release rate of S53P4 BG was confirmed to be three times faster in citric acid solution than that in tris buffer. Among them, the ion concentration of calcium and phosphorus initially increased and then gradually decreased, which is due to the biomineralization process. This process formed a new layer of particles on the surface of S53P4 BG, which was identified as a calcium-phosphate-based compound by X-ray diffraction analysis. Furthermore, the thickness of the layer was observed to be 273 nm in tris buffer and 34 nm in citric acid solution by focused-ion beam scanning electron microscopy, and the morphology of the particles comprising this layer was observed to be thicker and longer in tris buffer than that in citric acid solution. This difference is due to the citrate present in the citric acid solution interacting with the released calcium ions and inhibiting the formation of a new layer. Thus, the ion release of S53P4 BG was faster in citric acid solution than that in tris buffer, but the biomineralization process to form the calcium phosphate-based compound was more effective in tris buffer.

Electrophoretic Deposition of Bioactive Glass Coatings for Bone Implant Applications: A Review

This literature review deals with the electrophoretic deposition of bioactive glass coatings on metallic substrates to produce bone implants. Biocompatible metallic materials, such as titanium alloys or stainless steels, are commonly used to replace hard tissue functions because their mechanical properties are appropriate for load-bearing applications. However, metallic materials barely react in the body. They need a bioactive surface coating to trigger beneficial biological and chemical reactions in the physiological environment. Bioactive coatings aim to improve bone bonding, shorten the healing process after implantation, and extend the lifespan of the implant. Bioactive glasses, such as 45S5, 58S, S53P4, 13-93, or 70S30C, are amorphous materials made of a mixture of oxides that are accepted by the human body. They are used as coatings to improve the surface reactivity of metallic bone implants. Their high bioactivity in the physiological environment induces the formation of strong chemical bonding at the interface between the metallic implant and the surrounding bone tissue. Electrophoretic deposition is one of the most effective solutions to deposit uniform bioactive glass coatings at low temperatures. This article begins with a review of the different compositions of bioactive glasses described in the scientific literature for their ability to support hard tissue repair. The second part details the different stages of the bioactivity process occurring at the surface of bioactive glasses immersed in a physiological environment. Then, the mechanisms involved in the electrophoretic deposition of bioactive glass coatings on metallic bone implants are described. The last part of the article details the current developments in the process of improving the properties of bioactive glass coatings by adding biocompatible elements to the glassy structure.

Mechanical behaviour, in-vitro analysis, hemocompatibility and study of human osteosarcoma cell line proliferation of TiO2 substituted 1393-B3 borate glass

This investigation aimed to study the effects of adding TiO2 on many aspects of 1393-B3 glasses, including their physio-chemical, mechanical parameters, crystallization behaviour, in-vitro bioactivity, hemocompatibility, and cellular viability. Here, we replaced 1393 glass silica with boric oxide to determine a more effective alternative. 1393-B3 bioactive glasses having the general weight % composition (53-X) B2O3, 6 Na2O, 5 MgO, 20 CaO, 12 K2O, 4 P2O5, X TiO2 (where X = 0, 1.0, 1.5, 2.0, and 2.5 %) were prepared using solid-state melt quenching method in platinum crucible at 1100 °C for 2 h in an electric furnace with air as furnace atmosphere. This research aimed to investigate the complete substitution of 1393 glass silica with boric oxide in order to get a reduced melting temperature forming 1393-B3. The objective was to develop a more energy-efficient and economical bioactive glass. Thermal analysis of the samples was obtained up to 700 °C. To evaluate the in-vitro bioactivity, the samples were immersed in simulated body fluid (SBF). These materials undergo XRD, FTIR, and SEM/EDAX analysis both before and after soaking in SBF. These characterization results show the presence of a hydroxyapatite (HA) layer forming on the samples of the bioactive glass surface. The haemolysis process performed on human blood shows its haemocompatibility result. To test these results for the human body. We performed cell proliferation and cell compatibility on the MG-63 cell line to see its effect on osteosarcoma patients. Density (2.31–2.48 gm/cm3), pH value (7.4–8.86), and mechanical parameters such as compressive strength (98–125 MPa), flexural strength (33–54), and elasticity are measured. As a result, physio-chemical, mechanical, biological properties and in-vitro bioactivity of these samples were obtained with increasing concentration of TiO2 in 1393-B3 borate bioactive glass and found to increase with increasing concentration of TiO2.

A comparative analysis of the cytocompatibility, protein adsorption, osteogenic and angiogenic properties of the 45S5- and S53P4-bioactive glass compositions

Despite their long history of application in orthopedics, the osteogenic and angiogenic properties as well as the cytocompatibility and protein adsorption of the 45S5- (in wt%: 45.0 SiO2, 24.5 Na2O, 24.5 CaO, 6.0 P2O5) and S53P4- (in wt%: 53.0 SiO2, 23.0 Na2O, 20.0 CaO, 4.0 P2O5) bioactive glass (BG) compositions have not yet been directly compared in one and the same experimental setting. In this study, the influence of morphologically equal granules of both BGs on proliferation, viability, osteogenic differentiation and angiogenic response of human bone-marrow-derived mesenchymal stromal cells (BMSCs) was assessed. Furthermore, their impact on vascular tube formation and adsorption of relevant proteins was evaluated. Both BGs showed excellent cytocompatibility and stimulated osteogenic differentiation of BMSCs. The 45S5-BG showed enhanced stimulation of bone morphogenic protein 2 (BMP2) gene expression and protein production compared to S53P4-BG. While gene expression and protein production of vascular endothelial growth factor (VEGF) were stimulated, both BGs had only limited influence on tubular network formation. 45S5-BG adsorbed a higher portion of proteins, namely BMP2 and VEGF, on its surface. In conclusion, both BGs show favorable properties with slight advantages for 45S5-BG. Since protein adsorption on BG surfaces is important for their biological performance, the composition of the proteome formed by osteogenic cells cultured on BGs should be analyzed in order to gain a deeper understanding of the mechanisms that are responsible for BG-mediated stimulation of osteogenic differentiation.

Temperature-responsive bioactive glass/polymer hybrids allow for tailoring of ion release.

Intelligent biomaterials react to their surrounding conditions, and hybrid materials are acknowledged for their remarkable customizability, achieved through the meticulous control of nanoscale interactions between organic and inorganic phases. Bioactive glasses (BG) are used clinically to regenerate bone due to their degradability, ion release, and capacity to stimulate the formation of new body tissue. In our study, we developed a core-shell hybrid system using sol-gel derived BG nano particles as the core and poly (N-isopropyl acrylamide) (PNIPAM) as the shell. This approach aims to combine the therapeutic ion release of BG with the temperature-responsive properties of PNIPAM. Our size analysis by dynamic light scattering at varying temperatures shows the formation of BG aggregates driven by the coil-to-globule transition of PNIPAM on the BG surface. This transition also affected the ion release from the core-shell system through an increase in ion transport through the porous hybrid network. Our study therefore illustrates the ability to adjust the dissolution properties of the core-shell system via surrounding temperature and, thus, control the release of Ca ions from the BG.

Microwave-assisted fabrication of nanostructured borate bioactive glass and its bioactivity.

Sol-gel bioactive glass with nanocrystalline structures has demonstrated enhanced bioactivity and acceptance by the surrounding bone tissue. In particular, borate bioactive glasses exhibit higher reactivity and apatite formation under the simulated in vitro and in vivo conditions. This study presents a microwave-assisted synthesis of borate bioactive glass (58S) and an understanding of its structural and in vitro bioactivity. By this synthesis method, the nanocrystalline structures formed within the amorphous matrix will regulate the degradation rate of the glass network during apatite formation. The calcinated borate bioactive glass features a nanorod crystalline hydroxyapatite structure embedded in the amorphous borate glass network. The formation of apatite on the surface of borate bioactive glass within 6 hours of immersion in simulated body fluid confirms the material's enhanced bioactivity and reactivity. Anti-oxidant studies, cell viability, and alkaline phosphate activity further corroborate the bioactivity of borate bioactive glass. In summary, this study highlights the significant potential of microwave-synthesized borate bioactive glass for a wide range of bone tissue engineering applications.

The influencing mechanism of phosphorus component on network structure and bioactivity of bioactive glass

(64-x)SiO2–36CaO-xP2O5 (x = 0, 2, 4, 6, 8 mol%) bioactive glasses are successfully prepared by sol-gel method, and the effect of phosphorus (P) content on the network structure, phase composition and in vitro mineralization performance of bioactive glasses is investigated by the various characterization techniques. Results show that the as-prepared bioactive glass has the amorphous structure. With the increase of P content, it can be found in FT-IR spectra that the characteristic peaks of bending vibration corresponding to the P–O bond in PO43− gradually appear. Among, the typical 60S4P has the highest percentage (73.81%) of bridging oxygen (BO), indicating its highest aggregation degree of silicate network. Besides, the introduction of P2O5 results in the formation of monophosphate, which enable the bioactive glasses to dissolve rapidly in water or simulate body fluids (SBF) and crystallize to form hydroxyapatite (HA), thereby enhancing its biological activity. After soaking in SBF for 3 days, the irregular cauliflower-like HA particles appear on the surface of bioactive glass, and the appropriate amount of P addition in glass could result in its high bioactivity. Therefore, this study could provide a theoretical reference for the relationship between the network structure and bioactivity of bioactive glass.

Bismuth-coated 80S15C bioactive glass scaffolds for photothermal antitumor therapy and bone regeneration.

Background: Malignant bone tumors usually occur in young people and have a high mortality and disability rate. Surgical excision commonly results in residual bone tumor cells and large bone defects, and conventional radiotherapy and chemotherapy may cause significant side effects. In this study, a bifunctional Bi-BG scaffold for near-infrared (NIR)-activated photothermal ablation of bone tumors and enhanced bone defect regeneration is fabricated. Methods: In this study, we prepared the Bi-BG scaffold by in-situ generation of NIR-absorbing Bi coating on the surface of a 3D-printing bioactive glass (BG) scaffold. SEM was used to analyze the morphological changes of the scaffolds. In addition, the temperature variation was imaged and recorded under 808nm NIR laser irradiation in real time by an infrared thermal imaging system. Then, the proliferation of rat bone mesenchymal stem cells (rBMSCs) and Saos-2 on the scaffolds was examined by CCK-8 assay. ALP activity assay and RT-PCR were performed to test the osteogenic capacity. For in vivo experiments, the nude rat tumor-forming and rat calvarial defect models were established. At 8weeks after surgery, micro-CT, and histological staining were performed on harvested calvarial samples. Results: The Bi-BG scaffolds have outstanding photothermal performance under the irradiation of 808nm NIR at different power densities, while no photothermal effects are observed for pure BG scaffolds. The photothermal temperature of the Bi-BG scaffold can be effectively regulated in the range 26-100°C by controlling the NIR power density and irradiation duration. Bi-BG scaffolds not only significantly induces more than 95% of osteosarcoma cell death (Saos-2) in vitro, but also effectively inhibit the growth of bone tumors in vivo. Furthermore, they exhibit excellent capability in promoting osteogenic differentiation of rBMSCs and finally enhance new bone formation in the calvarial defects of rats. Conclusion: The Bi-BG scaffolds have bifunctional properties of photothermal antitumor therapy and bone regeneration, which offers an effective method to ablate malignant bone tumors based on photothermal effect.

Flame retardancy and smoke suppression of multi-metal doped mesoporous bio-glass based hybrid microsphere on epoxy resin

Bioactive glass (BG) has been a focus of research for biomedical applications due to its unique biological properties. Owning to its special composition (SiO2–CaO–P2O5) and structure, BG becomes a potential flame retardant. In this paper, a novel type of BGs was synthesized and employed as a flame retardant for epoxy resin (EP). To further improve its flame retardancy properties, firstly, the chemical compositions of BGs were modified by doping Cu, Zn, Sr ions into the SiO2 network by a sol-gel method combined with a template method and hydrothermal method; secondly, the microstructure of BGs was designed as a microsphere with a hollow mesoporous structure. Moreover, the obtained BGs were further functionalized with a polyphosphazene derivative (PZS) to integrate the excellent flame retardancy and mechanical properties. The results showed that Cu/Zn/Sr ions entered the SiO2 network, while PZS was successfully deposited on the surface of mesoporous BGs. An improved comprehensive performance including flame retardancy, smoke suppression and mechanical strength enhancement was achieved by the presence of multiple flame-retardant atoms (Cu, Zn, Sr, Si, P, S, N, Cl) in the mesoporous BG microspheres. This study successfully applied BGs with high biocompatibility as flame retardant, broadening the types and categories of flame retardants.

Antioxidant Effects of Bioactive Glasses (BGs) and Their Significance in Tissue Engineering Strategies.

Elevated levels of oxidative stress are usually observed following injuries, leading to impaired tissue repair due to oxidation-related chronic inflammation. Several attempts have been made to manage this unfavorable situation, and the use of biomaterials with antioxidant activity is showing great promise in tissue engineering and regenerative medicine approaches. Bioactive glasses (BGs) are a versatile group of inorganic substances that exhibit an outstanding regenerative capacity for both hard and soft damaged tissues. The chemical composition of BGs provides a great opportunity for imparting specific biological activities to them. On this point, BGs may easily become antioxidant substances through simple physicochemical modifications. For example, particular antioxidant elements (mostly cerium (Ce)) can be added to the basic composition of the glasses. On the other hand, grafting natural antioxidant substances (e.g., polyphenols) on the BG surface is feasible for making antioxidant substitutes with promising results in vitro. Mesoporous BGs (MBGs) were demonstrated to have unique merits compared with melt-derived BGs since they make it possible to load antioxidants and deliver them to the desired locations. However, there are actually limited in vivo experimental studies on the capability of modified BGs for scavenging free radicals (e.g., reactive oxygen species (ROS)). Therefore, more research is required to determine the actual potential of BGs in decreasing oxidative stress and subsequently improving tissue repair and regeneration. The present work aims to highlight the potential of different types of BGs in modulating oxidative stress and subsequently improving tissue healing.

Boswellia sacra Extract-Loaded Mesoporous Bioactive Glass Nano Particles: Synthesis and Biological Effects

Bioactive glasses (BGs) are being increasingly considered for numerous biomedical applications. The loading of natural compounds onto BGs to increase the BG biological activity is receiving increasing attention. However, achieving efficient loading of phytotherapeutic compounds onto the surface of bioactive glass is challenging. The present work aimed to prepare novel amino-functionalized mesoporous bioactive glass nanoparticles (MBGNs) loaded with the phytotherapeutic agent Boswellia sacra extract. The prepared amino-functionalized MBGNs showed suitable loading capacity and releasing time. MBGNs (nominal composition: 58 wt% SiO2, 37 wt% CaO, 5 wt% P2O5) were prepared by sol-gel-modified co-precipitation method and were successfully surface-modified by using 3-aminopropyltriethoxysilane (APTES). In order to evaluate MBGNs loaded with Boswellia sacra, morphological analysis, biological studies, physico-chemical and release studies were performed. The successful functionalization and loading of the natural compound were confirmed with FTIR, zeta-potential measurements and UV-Vis spectroscopy, respectively. Structural and morphological evaluation of MBGNs was done by XRD, SEM and BET analyses, whereas the chemical analysis of the plant extract was done using GC/MS technique. The functionalized MBGNs showed high loading capacity as compared to non-functionalized MBGNs. The release studies revealed that Boswellia sacra molecules were released via controlled diffusion and led to antibacterial effects against S. aureus (Gram-positive) bacteria. Results of cell culture studies using human osteoblastic-like cells (MG-63) indicated better cell viability of the Boswellia sacra-loaded MBGNs as compared to the unloaded MBGNs. Therefore, the strategy of combining the properties of MBGNs with the therapeutic effects of Boswellia sacra represents a novel, convenient step towards the development of phytotherapeutic-loaded antibacterial, inorganic materials to improve tissue healing and regeneration.

Custom-Made Poly(urethane) Coatings Improve the Mechanical Properties of Bioactive Glass Scaffolds Designed for Bone Tissue Engineering.

The replication method is a widely used technique to produce bioactive glass (BG) scaffolds mimicking trabecular bone. However, these scaffolds usually exhibit poor mechanical reliability and fast degradation, which can be improved by coating them with a polymer. In this work, we proposed the use of custom-made poly(urethane)s (PURs) as coating materials for 45S5 Bioglass®-based scaffolds. In detail, BG scaffolds were dip-coated with two PURs differing in their soft segment (poly(ε-caprolactone) or poly(ε-caprolactone)/poly(ethylene glycol) 70/30 w/w) (PCL-PUR and PCL/PEG-PUR) or PCL (control). PUR-coated scaffolds exhibited biocompatibility, high porosity (ca. 91%), and improved mechanical properties compared to BG scaffolds (2–3 fold higher compressive strength). Interestingly, in the case of PCL-PUR, compressive strength significantly increased by coating BG scaffolds with an amount of polymer approx. 40% lower compared to PCL/PEG-PUR- and PCL-coated scaffolds. On the other hand, PEG presence within PCL/PEG-PUR resulted in a fast decrease in mechanical reliability in an aqueous environment. PURs represent promising coating materials for BG scaffolds, with the additional pros of being ad-hoc customized in their physico-chemical properties. Moreover, PUR-based coatings exhibited high adherence to the BG surface, probably because of the formation of hydrogen bonds between PUR N-H groups and BG surface functionalities, which were not formed when PCL was used.

ZnO incorporated high phosphate bioactive glasses for guided bone regeneration implants: enhancement of in vitro bioactivity and antibacterial activity

Bioactive phosphate glasses incorporated with Zn 2+ (predicted to be useful for bone regeneration applications) were synthesized. Characterization of the bioglasses were done using XRD, FTIR, SEM, and EDS techniques, both prior to and after soaking in simulated body fluid (SBF) solution. The bioactive performance of samples was evaluated by incubated in SBF for different days by means of the pH measuring and comparing the results of XRD and SEM studies. The obtained results show the formation of hydroxyapatite (HAP) layer on the surface of as-developed bioactive glasses. The degradation of the samples evaluated by weight loss and pH of the remnant solution measured as functions of ZnO concentration and immersion time revealed the enhanced formation of HAP layer on the sample surface. The results further indicated the rate of degradation can be monitored by tailoring the concentration of ZnO and immersion time. The studies were also extended to in vitro cytocompatibility and cell proliferation measurements on rMSC using CCK-8 for incubation periods of 24 h and 72 h. These studies have revealed the considerable levels of rMSC proliferation and improved viability within the limits of nontoxic levels. The measurements of antibacterial activity of ZnO-doped phosphate bioactive glasses against E. coli and S. aureus, carried out for 24 h and 48 h have confirmed their potential antibacterial activity. Finally, quantitative analysis of these results confirmed an enhanced in vitro biological and antibacterial activity of the samples due to the ZnO doping and subsequent controlled release of Zn 2+ ions in the glass matrix.

Biological Evaluation of a New Sodium-Potassium Silico-Phosphate Glass for Bone Regeneration: In Vitro and In Vivo Studies.

In vitro and in vivo studies are fundamental steps in the characterization of new implantable materials to preliminarily assess their biological response. The present study reports the in vitro and in vivo characterizations of a novel experimental silicate bioactive glass (BG) (47.5B, 47.5SiO2-10Na2O-10K2O-10MgO-20CaO-2.5P2O5 mol.%). Cytocompatibility tests were performed using human mature osteoblasts (U2OS), human mesenchymal stem cells (hMSCs) and human endothelial cells (EA.hy926). The release of the early osteogenic alkaline phosphatase (ALP) marker suggested strong pro-osteogenic properties, as the amount was comparable between hMSCs cultivated onto BG surface and cells cultivated onto polystyrene control. Similarly, real-time PCR revealed that the osteogenic collagen I gene was overexpressed in cells cultivated onto BG surface without biochemical induction. Acute toxicity tests for the determination of the median lethal dose (LD50) allowed classifying the analyzed material as a slightly toxic substance with LD50 = 4522 ± 248 mg/kg. A statistically significant difference in bone formation was observed in vivo through comparing the control (untreated) group and the experimental one, proving a clear osteogenic effect induced by the implantation at the defect site. Complete resorption of 47.5B powder was observed after only 3 months in favor of newly formed tissue, thus confirming the high osteostimulatory potential of 47.5B glass.

Sintered S53P4 bioactive glass scaffolds have anti-inflammatory properties and stimulate osteogenesis in vitro

Bioactive glasses (BAG) are used as bone-graft substitutes in orthopaedic surgery. A specific BAG scaffold was developed by sintering BAG-S53P4 granules. It is hypothesised that this scaffold can be used as a bone substitute to fill bone defects and induce a bioactive membrane (IM) around the defect site. Beyond providing the scaffold increased mechanical strength, that the initial inflammatory reaction and subsequent IM formation can be enhanced by coating the scaffolds with poly(DL-lactide-co-glycolide) (PLGA) is also hypothesised. To study the immunomodulatory effects, BAG-S53P4 (± PLGA) scaffolds were placed on monolayers of primary human macrophage cultures and the production of various pro- and anti-inflammatory cytokines was assessed using reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) and ELISA. To study the osteogenic effects, BAG-S53P4 (± PLGA) scaffolds were cultured with rabbit mesenchymal stem cells and osteogenic differentiation was evaluated by RT-qPCR and matrix mineralisation assays. The scaffold ion release was quantified and the BAG surface reactivity visualised. Furthermore, the pH of culture media was measured. BAG-S53P4 scaffolds had both anti-inflammatory and osteogenic properties that were likely attributable to alkalinisation of the media and ion release from the scaffold. pH change, ion release, and immunomodulatory properties of the scaffold could be modulated by the PLGA coating. Contrary to the hypothesis, the coating functioned by attenuating the BAG surface reactions and subsequent anti-inflammatory properties, rather than inducing an elevated inflammatory response compared to BAG-S53P4 alone. These results further validated the use of BAG-S53P4 (± PLGA) scaffolds as bone substitutes and indicate that scaffold properties can be tailored to a specific clinical need.

Surface-treated 3D printed Ti-6Al-4V scaffolds with enhanced bone regeneration performance: an in vivo study.

BackgroundGiven their highly adjustable and predictable properties, three-dimensional(3D) printed geometrically ordered porous biomaterials offer unique opportunities as orthopedic implants. The performance of such biomaterials is, however, as much a result of the surface properties of the struts as it is of the 3D porous structure. In our previous study, we have investigated the in vitro performances of selective laser melted (SLM) Ti-6Al-4V scaffolds which are surface modified by the bioactive glass (BG) and mesoporous bioactive glass (MBG), respectively. The results demonstrated that such modification enhanced the attachment, proliferation, and differentiation of human bone marrow stromal cells (hBMSC). Here, we take the next step by assessing the therapeutic potential of 3D printed Ti-6Al-4V scaffolds with BG and MBG surface modifications for bone regeneration in a rabbit bone defect model.Methods3D printed Ti-6Al-4V scaffolds with BG and MBG surface modifications were implanted into the femoral condyle of the rabbits, the Ti-6Al-4V scaffolds without surface modification were used as the control. At week 3, 6, and 9 after the implantation, micro-computed tomography (micro-CT) imaging, fluorescence double-labeling to determine the mineral apposition rate (MAR), and histological analysis of non-decalcified sections were performed.ResultsWe found significantly higher volumes of regenerated bone, significantly higher values of the relevant bone morphometric parameters, clear signs of bone matrix apposition and maturation, and the evidence of progressed angiogenesis and blood vessel formation in the groups where the bioactive glass was added as a coating, particularly the MGB group.ConclusionsThe MBG coating resulted in enhanced osteoconduction and vascularization in bone defect healing, which was attributed to the release of silicon and calcium ions and the presence of a nano-mesoporous structure on the surface of the MBG specimens.

Synthesis and Characterization of 50S8P Bioglass through Sol Gel Method

Bioactive glasses (BG) were applied in bone and dental applications as well as in tissue engineering. In this studies, a new bioglass 50S8P (50% SiO2, 22% CaO, 20% Na2O and 8% P2O5) with different aging time (3, 7, 10 and 15 days) was prepared by sol-gel method. These synthesized glasses were analyzed using X- ray powder diffraction (XRD), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The bioactivity of all BG is evaluated by incubating the BG powder in Hank's Balanced Salt Solution (HBSS) for 7, 14 and 21 days. Thermal analyses indicated the compositions can be stabilized at 700°C. XRD confirmed the primary crystalline phase was Na4Ca4Si6O18. Formation of silica network is established with the existence of functional group Si-O-Si (tetrahedral), confirmed with FTIR analyses. In vitro test confirm the apatite formation on the BG surface with characteristic of carbonate group (C-O) and P-O band noticed from FTIR and morphology of apatite formation on BG surface was observe using SEM

A molecular dynamics study of the effect of water diffusion into bio-active phosphate-based glass surfaces on their dissolution behaviour

Classical molecular dynamics (MD) simulations were used to study the effects of water on the structural relaxation of the surfaces of bio-active phosphate-based glasses with compositions (P2O5)0.45(CaO)x(Na2O)0.55-x (x = 0.30, 0.35 and 0.40). Direct comparison of the data for the three compositions showed that surfaces with x = 0.30 experienced the highest calcium diffusion, as well as highest sodium concentration at the glass/water interface, confirming these systems as the most soluble of the three compositions studied. Our results also show the importance of surface hydroxylation in the simulation of these types of bio-glasses, which causes differential relaxation of the surfaces, leading to changes in network polymerization that modulate the diffusion of water and modifiers into and out of the glasses, with direct impact on dissolution.

Koh group influence on titanium surfaces and pure sol-gel silica for enhanced osteogenic activity.

Although, the excellent level of success of titanium surfaces is based on the literature, there are some biological challenges such as unfavorable metabolic conditions or regions of poor bone quality where greater surface bioactivity is desired. Seeking better performance, we hypothesized that silica-based coating via sol-gel route with immersion in potassium hydroxide basic solution induces acceleration of bone mineralization. This in vitro experimental study coated titanium surfaces with bioactive glass synthesized by route sol-gel via hydrolysis and condensation of chemical alkoxide precursor, tetraethylorthosilicate (TEOS) and/or deposition of chemical compound potassium hydroxide (KOH) to accelerate bone apposition. The generated surfaces titanium(T), titanium with potassium hydroxide deposition (T + KOH), titanium with bioactive glass deposition synthesized by sol-gel route via tetraethylorthosilicate hydrolysis (TEOS), titanium with bioactive glass deposition synthesized by sol-gel route via tetraethylorthosilicate hydrolysis with potassium hydroxide deposition (TEOS + KOH) were characterized by 3D optical profilometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle by the sessile drop method, x-ray excited photoelectron spectroscopy (XPS) and energy dispersive x-ray spectrometer (EDX). The addition of the KOH group on the pure titanium (T) or bioactive glass (TEOS) surfaces generated a tendency for better results for mineralization. Groups covered with bioactive glass (TEOS, TEOS + KOH) tended to outperform even groups with titanium substrate (T, T + KOH). The addition of both, bioactive glass and KOH, in a single pure titanium substrate yielded the best results for the mineralization process.