Borate Bioactive Glass Scaffolds Research Articles

Two-dimensional molybdenum disulfide/polymer-coated bioactive glass scaffolds for tissue engineering: Fabrication, structural, mechanical, bioactivity, and radiation interaction properties

Molybdenum disulfide (MoS2)-based nanostructures are widely used in environmental protection and biomedicine owing to their biological, physical, chemical, electrical, and mechanical properties. In this study, polycaprolactone (PCL)- and polylactide-co-glycolide (PLGA)-coated bioactive glass scaffolds containing MoS2 nanoparticles are prepared, and their usability in bone tissue engineering applications is evaluated. Borate bioactive glass scaffolds are fabricated using the replication method and coated with PCL or PLGA solutions (5 wt%) containing MoS2 (0.1, 0.2, 0.5, 1, and 2 wt%) nanoparticles. The structural and mechanical properties of the scaffolds and their bioactivity in simulated body fluids are investigated comprehensively. The ionization–radiation-shielding properties are investigated using Monte Carlo simulations. The results show that the polymer coating layer and presence of MoS2 nanoparticles in the polymer matrix improves the mechanical properties of the scaffolds. The addition of MoS2 nanoparticles to the structure increases the hydroxyapatite-forming ability of bioactive glass-based composites. Additionally, the prepared composite scaffolds exhibit high radiation-shielding ability owing to the presence of MoS2 nanoparticles embedded in the polymer matrix that shields the glass surface. Bioactive glass composite scaffolds containing MoS2 nanoparticles demonstrate promising potential for bone regeneration and radiation-shielding applications.

Hexagonal Boron Nitride/PCL/PLG Coatings on Borate Bioactive Glass Scaffolds for Bone Regeneration

Hexagonal Boron Nitride/PCL/PLG Coatings on Borate Bioactive Glass Scaffolds for Bone Regeneration

In vitro evaluation of novel titania-containing borate bioactive glass scaffolds.

Titanium-containing borate bioactive glass scaffolds (0, 5, 15, and 20 mol %, identified as BRT0, BRT1, BRT3, and BRT4) with a microstructure similar to that of human trabecular bone were prepared and evaluated in vitro for potential bone loss applications in revision total knee arthroplasty (rTKA). Methyl thiazolyl tetrazolium (MTT) cell viability assays of scaffold ion release extracts revealed that BRT0 scaffolds (0 mol % titanium) inhibited cell proliferation and activity at day 14. At day 30, all scaffold extracts decreased cell proliferation and activity significantly. However, live/dead cell assay results demonstrated that degradation products from all the scaffolds had no inhibitory effect on cell viability. Significant bactericidal efficacies of BRT3 extracts against Escherishia coli (Gram-negative) and BRT1 extracts against Staphylococcus aureus and Staphylococcus epidermidis (both Gram-positive bacteria) were demonstrated. Finally, evaluation of the cell/bioactive glass surface interactions showed well-spread cells on the surface of the BRT3 glass discs and BRT1 and BRT3 scaffolds, when compared to BRT0 and BRT4 scaffolds. The results indicate that by changing the Ti4+ :B3+ ratio, the ion release and consequently cell proliferation could be improved. in vitro results in this study demonstrate that BRT3 scaffolds could be a promising candidate for addressing bone loss in rTKAs; however, in vivo studies would be required to evaluate the effect of a dynamic environment on the cell and tissue response to the fabricated scaffolds.

Effect of TiO2 doping on degradation rate, microstructure and strength of borate bioactive glass scaffolds.

A titanium-containing borate glass series based on the system (52-X) B2O3-12CaO-6P2O5-14Na2O-16ZnO-XTiO2 with X varying from 0, 5 and 15 mol% of TiO2 incorporated, identified as BRT0, BRT1 and BRT3, respectively, were used in this study. Scaffolds (pore sizes, 165-230 μm and porosity, 53.51-69.51%) were prepared using a polymer foam replication technique. BRT3 scaffolds exhibited higher compressive strength (7.16 ± 0.22 MPa) when compared to BRT0 (6.02 ± 0.47 MPa) and BRT1 (5.65 ± 0.28 MPa) scaffolds with lower, or no, TiO2 content. The solubility of the scaffolds decreased as the TiO2 content increased up to 15 mol% when samples of each scaffold were immersed in DI water and the pH of all these extracts went up from 7.0 to 8.5 in 30 days. The cumulative ion release from the scaffolds showed significant difference with respect to TiO2 content; addition of 5 mol% TiO2 at the expense of borate (B2O3) decreased the ion release remarkably. Furthermore, it was found that for all three scaffolds, cumulative ion release increased with incubation time. The results indicate that the degradation rates and compressive strengths of borate bioactive glass scaffolds could be controlled by varying the amount of TiO2 incorporated, confirming their potential as scaffolds in TKA and rTKA.

Evaluation of three-dimensional silver-doped borate bioactive glass scaffolds for bone repair: Biodegradability, biocompatibility, and antibacterial activity

Abstract

Synthesis and characterization of cerium- and gallium-containing borate bioactive glass scaffolds for bone tissue engineering.

Bioactive glasses are widely used in biomedical applications due to their ability to bond to bone and even to soft tissues. In this study, borate based (13-93B3) bioactive glass powders containing up to 5 wt% Ce2O3 and Ga2O3 were prepared by the melt quench technique. Cerium (Ce+3) and gallium (Ga+3) were chosen because of their low toxicity associated with bacteriostatic properties. Bioactive glass scaffolds were fabricated using the polymer foam replication method. In vitro degradation and bioactivity of the scaffolds were evaluated in SBF under static conditions. Results revealed that the cerium- and gallium-containing borate glasses have much lower degradation rates compared to the bare borate glass 13-93B3. In spite of the increased chemical durability, substituted glasses exhibited a good in vitro bioactive response except when the Ce2O3 content was 5 wt%. Taking into account the high in vitro hydroxyapatite forming ability, borate glass scaffolds containing Ce+3 and Ga+3 therapeutic ions are promising candidates for bone tissue engineering applications.

Evaluation of borate bioactive glass scaffolds as a controlled delivery system for copper ions in stimulating osteogenesis and angiogenesis in bone healing.

Biocompatible synthetic scaffolds with enhanced osteogenic and angiogenic capacity are of great interest for the repair of large (critical size) bone defects. In this study, we investigated an approach based on the controlled delivery of copper (Cu) ions from borate bioactive glass scaffolds for stimulating angiogenesis and osteogenesis in a rodent calvarial defect model. Borate glass scaffolds (pore size = 200-400 μm) doped with varying amounts of Cu (0-3.0 wt% CuO) were created using a polymer foam replication technique. When immersed in simulated body fluid (SBF) in vitro, the scaffolds released Cu ions into the medium at a rate that was dependent on the amount of Cu in the glass and simultaneously converted to hydroxyapatite (HA). At the concentrations used, the Cu in the glass was not cytotoxic to human bone marrow derived stem cells (hBMSCs) cultured on the scaffolds and the alkaline phosphatase activity of the hBMSCs increased with increasing Cu in the glass. When implanted in rat calvarial defects for 8 weeks, the scaffolds doped with 3 wt% CuO showed a significantly better capacity to stimulate angiogenesis and regenerate bone when compared to the undoped glass scaffolds. Together, these results indicate that the controlled delivery of Cu ions from borate bioactive glass implants is a promising approach in healing bone defects.

In vitro assessment of degradation and mineralisation of V2O5 substituted borate bioactive glass scaffolds

Bioactive glasses are promising scaffold materials for bone regeneration because of their unique ability to convert to hydroxyapatite (HA) in vivo, and their ability to bond with bone and soft tissues. In this study, borate based (13-93B3) bioactive glass powders containing up to 3 wt-%V2O5 were prepared by the melt quench technique. Vanadium was chosen because of its therapeutic action. It is known to promote initial wound healing and this may be especially beneficial to applications involving diabetic patients and soft tissue healing. Bioactive glass scaffolds were fabricated using the polymer foam replication method. In vitro degradation and bioactivity of the scaffolds were evaluated in simulated body fluid under static conditions. Results revealed that the vanadium-containing borate glasses have higher degradation rates compared to the bare borate glass 13-93B3. Due to low chemical durability, substituted glasses exhibited a good in vitro bioactive response. Taking into account the high in vitro HA forming ability, borate glass scaffolds containing V+5 therapeutic ions are promising candidates for bone tissue engineering applications.

Size-dependent degradation and bioactivity of borate bioactive glass

Abstract Borate bioactive glass has been shown to convert faster and more completely to hydroxyapatite and enhances new bone formation in vivo when compared to silicate bioactive glass. In this work, bioactive borate glass scaffolds, with a grid-like microstructure having different filament diameters (130±10 µm to 300±20 µm), were prepared by a robotic deposition technique. In vitro degradation and hydroxyapatite formation on borate bioactive glass scaffolds were investigated in a simulated body fluid (SBF) at 37 °C under static conditions. Mineralization of borate and silicate bioactive glass powders was also tested under the same conditions. When immersed in SBF, degradation rate of the scaffolds and conversion to a hydroxyapatite-like material showed dependence on filament diameter. Similarly, conversion of bioactive glass particles to calcium phosphate phase strongly depends on the particle size and the sample/SBF ratio of the system. Large particles and scaffolds composed of thick struts formed less apatite and degraded less completely compared with smaller particles and thinner struts. Results showed that it is possible to tailor the degradation rate and bioactivity by changing the filament diameter of the borate bioactive glass scaffolds produced by robocasting.

Evaluation of borate bioactive glass scaffolds with different pore sizes in a rat subcutaneous implantation model

Borate bioactive glass has been shown to convert faster and more completely to hydroxyapatite and enhance new bone formation invivo when compared to silicate bioactive glass (such as 45S5 and 13-93 bioactive glass). In this work, the effects of the borate glass microstructure on its conversion to hydroxyapatite (HA) invitro and its ability to support tissue ingrowth in a rat subcutaneous implantation model were investigated. Bioactive borate glass scaffolds, designated 13-93B3, with a grid-like microstructure and pore widths of 300, 600, and 900 µm were prepared by a robocasting technique. The scaffolds were implanted subcutaneously for 4 weeks in Sprague Dawley rats. Silicate 13-93 glass scaffolds with the same microstructure were used as the control. The conversion of the scaffolds to HA was studied as a function of immersion time in a simulated body fluid. Histology and scanning electron microscopy were used to evaluate conversion of the bioactive glass implants to hydroxyapatite, as well as tissue ingrowth and blood vessel formation in the implants. The pore size of the scaffolds was found to have little effect on tissue infiltration and angiogenesis after the 4-week implantation.

Evaluation of bone regeneration, angiogenesis, and hydroxyapatite conversion in critical‐sized rat calvarial defects implanted with bioactive glass scaffolds

Bioactive glasses are biocompatible materials that convert to hydroxyapatite in vivo, and potentially support bone formation, but have mainly been available in particulate and not scaffold form. In this study, borosilicate and borate bioactive glass scaffolds were evaluated in critical-sized rat calvarial defects. Twelve-week-old rats were implanted with 45S5 silicate glass particles and scaffolds of 1393 silicate, 1393B1 borosilicate, and 1393B3 borate glass. After 12 weeks, the defects were harvested, stained with hematoxylin and eosin to evaluate bone regeneration, Periodic Acid Schiff to quantitate blood vessel area, and von Kossa and backscatter SEM to estimate newly mineralized bone and hydroxyapatite conversion of bioactive glasses. The amount of new bone was 12.4% for 45S5, 8.5% for 1393, 9.7% for 1393B1, and 14.9% for 1393B3 (*p = 0.04; cf. 1393 and 1393B1). Blood vessel area was significantly higher (p = 0.009) with 45S5 (3.8%), with no differences among 1393 (2.0%), 1393B1 (2.4%), or 1393B3 (2.2%). Percent von Kossa-positive area was 18.7% for 45S5, 25.4% for 1393, 29.5% for 1393B1, and 30.1% for 1393B3, significantly higher (p = 0.014) in 1393B1 and 1393B3 glasses than in 45S5. 45S5 and 1393B3 converted completely to HA in vivo. The 1393B3 glass provided greater bone formation and may be more promising for bone defect repair due to its capacity to be molded into scaffolds. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A 100A:3267-3275, 2012.

Direct-write assembly of silicate and borate bioactive glass scaffolds for bone repair

Abstract Silicate (13-93) and borate (13-93B3) bioactive glass scaffolds were created by robotic deposition (robocasting) of organic solvent-based suspensions and evaluated in vitro for potential application in bone repair. Suspensions (inks) were developed, characterized, and deposited layer-by-layer to form three-dimensional scaffolds with a grid-like microstructure (porosity ≈50%; pore width 420 ± 30 μm). The mechanical response of the scaffolds was tested in compression, and the conversion of the glass to hydroxyapatite (HA)-like material in a simulated body fluid (SBF) was evaluated. As fabricated, the 13-93 scaffolds had a compressive strength 142 ± 20 MPa, comparable to the strength of human cortical bone, while the strength of the 13-93B3 scaffolds (65 ± 11 MPa), was far higher than that for trabecular bone. When immersed in SBF, the borate 13-93B3 scaffolds converted faster than the silicate 13-93 scaffolds to an HA-like material, but they also showed a sharper decrease in strength with immersion time. Based on their high compressive strength and bioactivity, the scaffolds fabricated in this work by robocasting could have potential application in the repair of load-bearing bone.

In vitro assessment of degradation and bioactivity of robocast bioactive glass scaffolds in simulated body fluid

In this study porous three-dimensional scaffolds of borate (13-93B3) bioactive glass were prepared by robocasting and in vitro degradation and bioactivity was evaluated. Grid like scaffolds with interconnected pores was assembled using robotic deposition technique which is a direct ink writing method. After binder burnout, the constructs were sintered for 1h at 560°C to produce scaffolds (porosity≈60%) consisting of dense glass struts (300±20μm in diameter) and interconnected pores of width 580±20μm. Hydroxyapatite formation on borate bioactive glass scaffolds was investigated in simulated body fluid (SBF) using three different scaffold/SBF (S/S) ratios (1, 2 and 10mg/ml) at 37°C. When immersed in SBF, degradation rate of the scaffolds and conversion to a calcium phosphate material showed a strong dependence to the S/S ratio. At high solid concentration (10mg/ml) surface of the glass scaffolds converted to the calcium rich amorphous calcium phosphate after 30 days. At lower solid concentrations (2 and 1mg/ml) an amorphous calcium phosphate layer formation was observed followed by the conversion to hydroxyapatite.

Silicate, borosilicate, and borate bioactive glass scaffolds with controllable degradation rate for bone tissue engineering applications. I. Preparation and in vitro degradation

Bioactive glass scaffolds with a microstructure similar to that of dry human trabecular bone but with three different compositions were evaluated for potential applications in bone repair. The preparation of the scaffolds and the effect of the glass composition on the degradation and conversion of the scaffolds to a hydroxyapatite (HA)-type material in a simulated body fluid (SBF) are reported here (Part I). The in vitro response of osteogenic cells to the scaffolds and the in vivo evaluation of the scaffolds in a rat subcutaneous implantation model are described in Part II. Scaffolds (porosity = 78-82%; pore size = 100-500 microm) were prepared using a polymer foam replication technique. The glasses consisted of a silicate (13-93) composition, a borosilicate composition (designated 13-93B1), and a borate composition (13-93B3), in which one-third or all of the SiO2 content of 13-93 was replaced by B2O3, respectively. The conversion rate of the scaffolds to HA in the SBF increased markedly with the B2O3 content of the glass. Concurrently, the pH of the SBF also increased with the B2O3 content of the scaffolds. The compressive strengths of the as-prepared scaffolds (5-11 MPa) were in the upper range of values reported for trabecular bone, but they decreased markedly with immersion time in the SBF and with increasing B2O3 content of the glass. The results show that scaffolds with a wide range of bioactivity and degradation rate can be achieved by replacing varying amounts of SiO(2) in silicate bioactive glass with B2O3.

Silicate, borosilicate, and borate bioactive glass scaffolds with controllable degradation rate for bone tissue engineering applications. II. In vitro and in vivo biological evaluation

In Part I, the in vitro degradation of bioactivAR52115e glass scaffolds with a microstructure similar to that of human trabecular bone, but with three different compositions, was investigated as a function of immersion time in a simulated body fluid. The glasses consisted of a silicate (13-93) composition, a borosilicate composition (designated 13-93B1), and a borate composition (13-93B3), in which one-third or all of the SiO2 content of 13-93 was replaced by B2O3, respectively. This work is an extension of Part I, to investigate the effect of the glass composition on the in vitro response of osteogenic MLO-A5 cells to these scaffolds, and on the ability of the scaffolds to support tissue infiltration in a rat subcutaneous implantation model. The results of assays for cell viability and alkaline phosphatase activity showed that the slower degrading silicate 13-93 and borosilicate 13-93B1 scaffolds were far better than the borate 13-93B3 scaffolds in supporting cell proliferation and function. However, all three groups of scaffolds showed the ability to support tissue infiltration in vivo after implantation for 6 weeks. The results indicate that the required bioactivity and degradation rate may be achieved by substituting an appropriate amount of SiO2 in 13-93 glass with B2O3, and that these trabecular glass scaffolds could serve as substrates for the repair and regeneration of contained bone defects.

Bioactive borate glass scaffolds: in vitro and in vivo evaluation for use as a drug delivery system in the treatment of bone infection

The objective of this work was to evaluate borate bioactive glass scaffolds (with a composition in the system Na(2)O-K(2)O-MgO-CaO-B(2)O(3)-P(2)O(5)) as devices for the release of the drug Vancomycin in the treatment of bone infection. A solution of ammonium phosphate, with or without dissolved Vancomycin, was used to bond borate glass particles into the shape of pellets. The in vitro degradation of the pellets and their conversion to a hydroxyapatite-type material in a simulated body fluid (SBF) were investigated using weight loss measurements, chemical analysis, X-ray diffraction, and scanning electron microscopy. The results showed that greater than 90% of the glass in the scaffolds degraded within 1 week, to form poorly crystallized hydroxyapatite (HA). Pellets loaded with Vancomycin provided controlled release of the drug over 4 days. Vancomycin-loaded scaffolds were implanted into the right tibiae of rabbits infected with osteomyelitis. The efficacy of the treatment was assessed using microbiological examination and histology. The HA formed in the scaffolds in vivo, resulting from the conversion of the glass, served as structure to support the growth of new bone and blood vessels. The results in this work indicate that bioactive borate glass could provide a promising biodegradable and bioactive material for use as both a drug delivery system and a scaffold for bone repair.