Conventional Bioactive Glasses Research Articles

A COMPARATIVE STUDY OF THREE DIFFERENT BIOACTIVE GLASS SCAFFOLDS TAILORED FOR CARTILAGE TISSUE ENGINEERING

The regenerative capacity of hyaline cartilage is greatly limited. To prevent the onset of osteoarthritis, cartilage defects have to be properly treated. Cartilage, tissue engineered by mean of bioactive glass (BG) scaffolds presents a promising approach. Until now, conventional BGs have been used mostly for bone regeneration, as they are able to form a hydroxyapatite (HA) layer and are therefore, less suited for cartilage reconstruction. The aim of this study is to compare two BGs based on a novel BG composition tailored specifically for cartilage (CAR12N) and patented by us with conventional BG (BG1393) with a similar topology. The highly porous scaffolds consisting of 100% BG (CAR12N, CAR12N with low Ca2+/Mg2+ and BG1393) were characterized and dynamically seeded with primary porcine articular chondrocytes (pACs) or primary human mesenchymal stem cells (hMSCs) for up to 21 days. Subsequently, cell viability, DNA and glycosaminoglycan contents, cartilage-specific gene and protein expression were evaluated. The manufacturing process led to a comparable high (over 80%) porosity in all scaffold variants. Ion release and pH profiles confirmed bioactivity for them. After both, 7 and 21 days, more than 60% of the total surfaces of all three glass scaffold variants was densely colonized by cells with a vitality rate of more than 80%. The GAG content was significantly higher in BG1393 colonized with pACs. In general, the GAG content was higher in pAC colonized scaffolds in comparison to those seeded with hMSCs. The gene expression of cartilage-specific collagen type II, aggrecan, SOX9 and FOXO1 could be detected in all scaffold variants, irrespectively whether seeded with pACs or hMSCs. Cartilage-specific ECM components could also be detected at the protein level. In conclusion, all three BGs allow the maintenance of the chondrogenic phenotype or chondrogenic differentiation of hMSCs and thus, they present a high potential for cartilage regeneration.

Improved Flexural Properties of Experimental Resin Composites Functionalized with a Customized Low-Sodium Bioactive Glass.

This study evaluated the flexural properties of an experimental composite series functionalized with 5–40 wt% of a low-Na F-containing bioactive glass (F-series) and compared it to another experimental composite series containing the same amounts of the conventional bioactive glass 45S5 (C-series). Flexural strength and modulus were evaluated using a three-point bending test. Degree of conversion was measured using Fourier-transform infrared spectroscopy. Weibull analysis was performed to evaluate material reliability. The control material with 0 wt% of bioactive glass demonstrated flexural strength values of 105.1–126.8 MPa). In the C-series, flexural strength ranged between 17.1 and 121.5 MPa and was considerably more diminished by the increasing amounts of bioactive glass than flexural strength in the F-series (83.8–130.2 MPa). Analogously, flexural modulus in the C-series (0.56–6.66 GPa) was more reduced by the increase in bioactive glass amount than in the F-series (5.24–7.56 GPa). The ISO-recommended “minimum acceptable” flexural strength for restorative resin composites of 80 MPa was achieved for all materials in the F-series, while in the C-series, the materials with higher bioactive glass amounts (20 and 40 wt%) failed to meet the requirement of 80 MPa. The degree of conversion in the F-series was statistically similar or higher compared to that of the control composite with no bioactive glass, while the C-series showed a declining degree of conversion with increasing bioactive glass amounts. In summary, the negative effect of the addition of bioactive glass on mechanical properties was notably less pronounced for the customized bioactive glass than for the bioactive glass 45S5; additionally, mechanical properties of the composites functionalized with the customized bioactive glass were significantly less diminished by artificial aging. Hence, the customized bioactive glass investigated in the present study represents a promising candidate for functionalizing ion-releasing resin composites.

Anti-demineralizing protective effects on enamel identified in experimental and commercial restorative materials with functional fillers

The aim of this study was to investigate whether experimental and commercial dental restorative materials with functional fillers can exert a protective anti-demineralizing effect on enamel that is not immediately adjacent to the restoration. Four experimental resin composites with bioactive glass and three commercial restorative materials were investigated. Enamel blocks were incubated in a lactic acid solution (pH = 4.0) at a standardized distance (5 mm) from cured specimens of restorative materials. The lactic acid solution was replenished every 4 days up to a total of 32 days. Surfaces of enamel blocks were periodically evaluated by Knoop microhardness measurements and scanning electron microscopy. The protective effect of restorative materials against acid was identified as enamel microhardness remaining unchanged for a certain number of 4-day acid addition cycles. Additionally, the pH of the immersion medium was measured. While enamel microhardness in the control group was maintained for 1 acid addition cycle (4 days), restorative materials postponed enamel softening for 2–5 cycles (8–20 days). The materials capable of exerting a stronger alkalizing effect provided longer-lasting enamel protection. The protective and alkalizing effects of experimental composites improved with higher amounts of bioactive glass and were better for conventional bioactive glass 45S5 compared to a fluoride-containing bioactive glass. Scanning electron micrographs evidenced the protective effect of restorative materials by showing a delayed appearance of an etching pattern on the enamel surface. A remotely-acting anti-demineralizing protective effect on enamel was identified in experimental composites functionalized with two types of bioactive glass, as well as in three commercial ion-releasing restorative materials.

Ipriflavone-Loaded Mesoporous Nanospheres with Potential Applications for Periodontal Treatment.

The incorporation and effects of hollow mesoporous nanospheres in the system SiO2–CaO (nanoMBGs) containing ipriflavone (IP), a synthetic isoflavone that prevents osteoporosis, were evaluated. Due to their superior porosity and capability to host drugs, these nanoparticles are designed as a potential alternative to conventional bioactive glasses for the treatment of periodontal defects. To identify the endocytic mechanisms by which these nanospheres are incorporated within the MC3T3-E1 cells, five inhibitors (cytochalasin B, cytochalasin D, chlorpromazine, genistein and wortmannin) were used before the addition of these nanoparticles labeled with fluorescein isothiocyanate (FITC–nanoMBGs). The results indicate that nanoMBGs enter the pre-osteoblasts mainly through clathrin-dependent mechanisms and in a lower proportion by macropinocytosis. The present study evidences the active incorporation of nanoMBG–IPs by MC3T3-E1 osteoprogenitor cells that stimulate their differentiation into mature osteoblast phenotype with increased alkaline phosphatase activity. The final aim of this study is to demonstrate the biocompatibility and osteogenic behavior of IP-loaded bioactive nanoparticles to be used for periodontal augmentation purposes and to shed light on internalization mechanisms that determine the incorporation of these nanoparticles into the cells.

Engineering stiffness in highly porous biomimetic gelatin/tertiary bioactive glass hybrid scaffolds using graphene nanosheets

Class II organic-inorganic hybrid materials have emerged as a promising replacement for the conventional bioactive glass particle-polymer composite biomaterials. Although these materials benefit from several advantages, such as controlled congruent degradation and improved cell response compared with the conventional composites, they become brittle when the inorganic-to-organic ratio exceeds an optimum value, rendering them unsuitable for tissue engineering applications. Here, a series of hybrid composite scaffolds were prepared from gelatin, tertiary bioactive glass and graphene oxide (GO) using a sol-gel/gas foaming technique. This study shows that rather than increasing the inorganic concentration to increase the mechanical stiffness, a small amount of GO (1 and 2 wt%) can be used to remarkably improve the Young's modulus of hybrid materials, by about 200%, without deteriorating the strain to failure. The hybrid scaffolds underwent a linear biodegradation, and a remarkable bioactivity reflected in a thick layer of hydroxyapatite formed on their surfaces after 14 days of immersion in carbonate buffered Dulbecco's modified Eagle's medium. The excellent biocompatibility of these scaffolds towards human adipose-derived mesenchymal stromal cells was confirmed in vitro. GO-doped organic-inorganic hybrid composite scaffolds may be ideal materials for a range of tissue engineering applications such as interface and non-load bearing bone tissue engineering.

A New Customized Bioactive Glass Filler to Functionalize Resin Composites: Acid-Neutralizing Capability, Degree of Conversion, and Apatite Precipitation.

This study introduced an experimental bioactive glass (BG) with a lower Na2O content than conventional BG 45S5 (10.5 wt% vs. 24.5 wt%), additionally containing CaF2 (12 wt%) and a network connectivity similar to that of BG 45S5. A series of experimental composites functionalized with 5–40 wt% of the novel BG was prepared and compared to a corresponding series of experimental composites functionalized with 5–40 wt% of BG 45S5. Commercial acid-neutralizing materials (alkasite, giomer, and glass ionomer) were used as references. The capabilities of the materials to neutralize hydrochloric acid (pH = 2.6) and lactic acid (pH = 4.5) were evaluated by real-time pH measurements over 1 h. The degree of conversion and precipitation of calcium phosphate were also investigated. Data were analyzed using one-way and Welch ANOVA at an overall level of significance of 0.05. The acid-neutralizing potential of the experimental BG incorporated into resin composites was generally comparable to that of BG 45S5, and better than that of a giomer and glass ionomer. Fluorine was identified in the precipitate that developed on the composites functionalized with the experimental BG, suggesting a capability of forming fluorapatite. Unlike the 45S5 composition, the experimental BG did not impair the degree of conversion of resin composites. The novel BG filler is therefore an interesting candidate for future investigations of caries-preventive resin composites, and their potential clinical applicability for restorative, preventive, and orthodontic purposes.

In situ preparation of multicomponent polymer composite nanofibrous scaffolds with enhanced osteogenic and angiogenic activities

Bioactive ceramics are extensively used for bone repair and regeneration, which release ions to initiate apatite formation and promote osteogenic differentiation eventually resulting in strong bonding to bone. Toward enhancing the bioactivity of polymeric nanofibrous scaffolds, this work presents a one-step in situ sol-gel method to fabricate electrospun composite nanofibrous scaffolds encapsulating well dispersed ceramic nanoparticles overcoming the limitations of current preparation techniques. Transmission electron micrographs revealed uniform distribution of ceramic nanoparticles within the polymer nanofibers. The multicomponent scaffolds were found to release calcium, silicon and phosphate ions that mimic the dissolution and bioactivity of conventional bioactive glasses. The scaffolds enhanced the bioactivity of PCL fibers as observed through enhanced apatite formation in simulated body fluid. The released ions markedly enhanced the proliferation and osteogenic differentiation of human mesenchymal stem cells and the angiogenic activity of human endothelial cells in vitro. This work has important implications for engineering the next-generation nanostructured scaffolds that exhibit multi-biofunctional activities for bone tissue regeneration.

Micro Hardness Of Bleached Human Enamel Following Application Of Conventional Versus Nano Active Bioglass: An Invitro Study

Objectives: The aim of this study was to compare the effect of conventional vesrsus nanosized bioactive glass on the microhardness values of bleached enamel.Methods: Forty-five fresh extracted human incisors were divided into three main groups (15 each) according to the bleaching technique (B); unbleached (B0) as a Control, light activated bleaching (B1) and chemical activated bleaching (B2). Each group was further divided equally into three subgroups (5 each) according to application of remineralizing agent (R); either conventional bioactive glass (R1), nano bioactive glass (R2) and without application of any remineralizing agent as a control (R0). Teeth bleaching was done as per the manufacturer’s instructions, while, remineralizing agents were applied according to wang et al 2011. Microhardness assessment was done after bleaching as well as after remineralization using Digital Display Vickers Microhardness Tester.Results: The unbleached group showed the highest mean microhardness followed by chemically activated bleaching group, then the light activated bleaching group. Regarding remineralization; nano bioactive glass groups showed higher microhardness results than conventional bioactive glass groups.Conclusions: Bleaching has a deleterious effect on enamel microhardness. Bioactive glass can counter act the adverse effect of bleaching on enamel. Nanobioactive glass is a promising material for remineralization

Acid catalysed synthesis of bioactive glass by evaporation induced self assembly method

Bioactive glass (BG) with uniform spherical morphology was prepared by EISA (Evaporation Induced Self Assembly) process using non-ionic Pluronic F127 as structure directing agent and phosphoric acid as a source of P2O5 and compared with conventional precursor triethyl phosphate (TEP). EISA method proceeds through ionic interaction mechanism by protonation of surfactant and silicic species. H3PO4 provides H+ and PO43− ions in reaction medium which play critical role in reaction mechanism. Hydrogen ions increase the protonation of H2O and surfactant, while PO43− ions act as bridging molecule between different cations, ensuring incorporation of phosphorus in BG network. TEP participates by proton acceptance mechanism, creating competitive environment. Thus H3PO4 facilitates the formation of BG in presence of non-ionic surfactant Pluronic F127. The prepared glasses were characterized by FTIR, SEM-EDX, TGA-DSC and BET surface analyzer. Uniform spherical morphology, improved dispersity, relatively large surface area and better cells focal attachment were observed for BG-H3PO4, prepared by using H3PO4. SiO2–CaO–P2O5 mol% composition of BG-H3PO4 was (66:24:10) close to the theoretical value (65:25:10), while for BG-TEP the actual ratio was (77:20.5:2.5). The surface reactivity, studied by soaking in simulated body fluid, showed rapid growth of hydroxyapatite with Ca/P ratio 1.67 on BG-H3PO4. The proliferation of MC3T3 cells on BG-H3PO4 was remarkably improved as compared to conventional BG. Thus BG-H3PO4 can be considered for biomedical applications in future especially for drug loading and composite application where homogeneous and uniform structure are of utmost importance.

Mesoporous Bioactive Glass Functionalized 3D Ti-6Al-4V Scaffolds with Improved Surface Bioactivity.

Porous Ti-6Al-4V scaffolds fabricated by means of selective laser melting (SLM), having controllable geometrical features and preferable mechanical properties, have been developed as a class of biomaterials that hold promising potential for bone repair. However, the inherent bio-inertness of the Ti-6Al-4V alloy as the matrix of the scaffolds results in a lack in the ability to stimulate bone ingrowth and regeneration. The aim of the present study was to develop a bioactive coating on the struts of SLM Ti-6Al-4V scaffolds in order to add the desired surface osteogenesis ability. Mesoporous bioactive glasses (MBGs) coating was applied on the strut surfaces of the SLM Ti-6Al-4V scaffolds through spin coating, followed by a heat treatment. It was found that the coating could maintain the characteristic mesoporous structure and chemical composition of MBG, and establish good interfacial adhesion to the Ti-6Al-4V substrate. The compressive strength and pore interconnectivity of the scaffolds were not affected by the coating. Moreover, the results obtained from in vitro cell culture experiments demonstrated that the attachment, proliferation, and differentiation of human bone marrow stromal cells (hBMSCs) on the MBG-coated Ti-6Al-4V scaffolds were improved as compared with those on the conventional bioactive glass (BG)-coated Ti-6Al-4V scaffolds and bare-metal Ti-6Al-4V scaffolds. Our results demonstrated that the MBG coating by using the spinning coating method could be an effective approach to achieving enhanced surface biofunctionalization for SLM Ti-6Al-4V scaffolds.

An easy-to-use wound dressing gelatin-bioactive nanoparticle gel and its preliminary in vivo study.

Beyond promoting hard tissue repairing, bioactive glasses (BGs) have also been proved to be beneficial for wound healing. Nano-scale BGs prepared by sol-gel method were found to have a better performance as they have a larger specific surface area. In this work, bioactive nanoparticles (nBPs) with mean diameter of 12 nm (BP-12) instead of conventional BGs were mixed with gelatin to form an easy-to-use hydrogel as a dressing for skin wound. It was found that the composite of BP-12 and gelatin could form a hydrogel (BP-12/Gel) under 25 °C, which showed pronounced thixotropy at a practically accessible shear rate, therefore become easy to be used for wound cover. In vitro, the composite hydrogel of BP-12 and gelatin had good biocompatibility with the fibroblast cells. In vivo, rapid cutaneous-tissue regeneration and tissue-structure formation within 7 days was observed in the wound-healing experiment performed in rats. This hydrogel is thus a promising easy-to-use wound dressing material.

Bioactivity and Mechanical Stability of 45S5 Bioactive Glass Scaffolds Based on Natural Marine Sponges.

Bioactive glass (BG) based scaffolds (45S5 BG composition) were developed by the replica technique using natural marine sponges as sacrificial templates. The resulting scaffolds were characterized by superior mechanical properties (compression strength up to 4MPa) compared to conventional BG scaffolds prepared using polyurethane (PU) packaging foam as a template. This result was ascribed to a reduction of the total scaffold porosity without affecting the pore interconnectivity (>99%). It was demonstrated that the reduction of total porosity did not affect the bioactivity of the BG-based scaffolds, tested by immersion of scaffolds in simulated body fluid (SBF). After 1day of immersion in SBF, a homogeneous CaP deposit on the surface of the scaffolds was formed, which evolved over time into carbonate hydroxyapatite(HCA). Moreover, the enhanced mechanical properties of these scaffolds were constant over time in SBF; after an initial reduction of the maximum compressive strength upon 7days of immersion in SBF (to 1.2±0.2MPa), the strength values remained almost constant and higher than those of BG-based scaffolds prepared using PU foam (<0.05MPa). Preliminary cell culture tests with Saos-2 osteoblast cell line, namely direct and indirect tests, demonstrated that no toxic residues remained from the natural marine sponge templates and that cells were able to proliferate on the scaffold surfaces.

Mesoporous bioactive glass nanolayer-functionalized 3D-printed scaffolds for accelerating osteogenesis and angiogenesis.

The hierarchical microstructure, surface and interface of biomaterials are important factors influencing their bioactivity. Porous bioceramic scaffolds have been widely used for bone tissue engineering by optimizing their chemical composition and large-pore structure. However, the surface and interface of struts in bioceramic scaffolds are often ignored. The aim of this study is to incorporate hierarchical pores and bioactive components into the bioceramic scaffolds by constructing nanopores and bioactive elements on the struts of scaffolds and further improve their bone-forming activity. Mesoporous bioactive glass (MBG) modified β-tricalcium phosphate (MBG-β-TCP) scaffolds with a hierarchical pore structure and a functional strut surface (∼100 nm of MBG nanolayer) were successfully prepared via 3D printing and spin coating. The compressive strength and apatite-mineralization ability of MBG-β-TCP scaffolds were significantly enhanced as compared to β-TCP scaffolds without the MBG nanolayer. The attachment, viability, alkaline phosphatase (ALP) activity, osteogenic gene expression (Runx2, BMP2, OPN and Col I) and protein expression (OPN, Col I, VEGF, HIF-1α) of rabbit bone marrow stromal cells (rBMSCs) as well as the attachment, viability and angiogenic gene expression (VEGF and HIF-1α) of human umbilical vein endothelial cells (HUVECs) in MBG-β-TCP scaffolds were significantly upregulated compared with conventional bioactive glass (BG)-modified β-TCP (BG-β-TCP) and pure β-TCP scaffolds. Furthermore, MBG-β-TCP scaffolds significantly enhanced the formation of new bone in vivo as compared to BG-β-TCP and β-TCP scaffolds. The results suggest that application of the MBG nanolayer to modify 3D-printed bioceramic scaffolds offers a new strategy to construct hierarchically porous scaffolds with significantly improved physicochemical and biological properties, such as mechanical properties, osteogenesis, angiogenesis and protein expression for bone tissue engineering applications, in which the incorporation of nanostructures and bioactive components into the scaffold struts synergistically play a key role in the improved bone formation.

Effects of bioactive glass with and without mesoporous structures on desensitization in dentinal tubule occlusion

Bioactive glass (BG) is a potential material for treating dentin hypersensitivity due to its high ability of dissolution. In this study, conventional BG and BG with well-ordered mesopore structures (MBG) were applied for dentinal tubule occlusion. We used X-ray diffractometer (XRD), scanning electronic microscope (SEM), and Fourier transform infrared (FTIR) to investigate the physiochemical properties and the dentinal tubule occlusion ability of BG and MBG groups. The results showed that the major crystallite phase of MBG and BG agents was monocalcium phosphate monohydrate. MBG pastes, mixed with 30 and 40wt% phosphoric acid hardening solutions, had the ability to create a penetration depth greater than 50μm. These results showed that BG with mesoporous structures turned the pastes mixed with suitable phosphoric acid solution into a material with great ability for occluding dentinal tubules; it has a short reaction time and good operability, and these agents have better potential for the treatment of dentin hypersensitivity than BG without mesoporous structures.

Nanoscale Bioactive Glasses in Medical Applications

This review focuses on recent advances in the development and use of nanoscale silicate bioactive glasses for medical applications. In the context of materials for bone substitution, dental applications, and bone tissue engineering, nanoscale bioactive glasses have been gaining attention due to their expected superior osteoconductivity when compared with conventional (micrometer‐sized) bioactive glass materials. A detailed overview of recent developments in the field of nanoscale bioactive glasses will be given, including a summary of common fabrication methods and diverse application areas which include tissue engineering scaffolds and coatings, drug delivery devices, and dentistry. The nanofeatures characteristic of this type of bioactive glasses and the possibilities to expand their use in biomedical applications (nanomedicine) are highlighted.

Synthesis and Characterization of Mesoporous SiO&lt;sub&gt;2&lt;/sub&gt;&amp;ndash;CaO&amp;ndash;P&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; Bioactive Glass by Sol&amp;ndash;Gel Process

Ordered mesoporous SiO2–CaO–P2O5 bioactive glass with a highly specific surface area has been synthesized through a sol–gel process in the presence of a nonionic triblock copolymer acting as a template. The amorphous silicate can be detected on the mesoporous SiO2–CaO–P2O5 bioactive glass. The mesoporous SiO2–CaO–P2O5 bioactive glass exhibits the type IV isotherm curve with average pore size of 5.3 nm and high specific surface area of 317.24 m2/g for calcination at 600°C. Owing to the high specific surface area and pore volume, the mesoporous SiO2–CaO–P2O5 had a significantly enhanced bone-forming bioactivity compared with the conventional bioactive glass. After soaking the mesoporous SiO2–CaO–P2O5 in simulated body fluid (SBF) for 10 h, it can be observed that the formation of apatite nanocrystals occurs on the surface of the bioactive glass. It is anticipated that mesoporous SiO2–CaO–P2O5 with a controlled mesostructure may be potentially useful as novel tissue-engineering scaffolds in bone regeneration.

Synthesis and in-vitro bioactivity of mesoporous bioactive glasses with tunable macropores

By using a nonionic block copolymer surfactant as the mesostructure directing agent, polystyrene (PS) colloidal particles or polyester (Terylene®) fibers as the macropore templates, mesoporous bioactive glass (MBG) materials with tunable macropores in a wide range (0.6–200 μm) have been synthesized and their in vitro bioactivities have been studied. Macro-mesoporous bioactive glass (MMBG) materials obtained by using PS spherical templates have a uniform macropore size of ∼600 nm, while MBG materials synthesized in the presence of terylene fibers have tubular channels (denoted TMBG) with diameters in the range of 8–200 μm adjusted by the diameters of terylene fibers. Both MMBG and TMBG materials have uniform mesopores of ∼5 nm in diameter. Similar to MBG materials, MMBG and TMBG materials have superior in vitro bioactivity compared to conventional bioactive glass. It is also shown that the size of macropore exerts influence on the hydroxycarbonate apatite (HCA) growth behavior within macropores. After soaking MMBG in simulated body fluid, HCA spheres gradually grow to sizes comparable to that of macro-pores after 24 h. While in the case of TMBG, hollow HCA tubes form in the tubular channels of TMBG. It is expected MBG materials with tunable macropores and exceptional in vitro bioactivity may find potential applications in delivery of biological factors, tissue ingrowth, tissue regeneration and neovascularization.

Study on the Loading and Releasing Behavior of Epirubicin Hydrochloride from Mesoporous Bioactive Glasses (MBGs)

Mesoporous bioactive glasses m58S were loaded with an anticancer drug-Epirubicin hydrochloride(EPI) and the release of the drug from the glasses was evaluated.The drug loading capacity of m58S for EPI was 40%, which was three times higher than that of conventional Sol-Gel bioactive glasses 58S.In phosphate buffered saline (PBS),the m58S-EPI system showed a sustained release behavior.Furthermore,the release rates from the EPI-m58S system increased with the decrease of pH values of the release medium.The results suggest that m58S is an effective anticancer drug carrier and its pH-related release behavior suggests that it has potential for design of controlled drug delivery bone grafting materials.

A New Calcium Source for Bioactive Sol-Gel Hybrids

Poly(γ-glutamic acid) (γ-PGA) has been intro- duced into sol-gel derived silica to produce an organic/ inorganic hybrid system to improve the toughness of conventional bioactive glass. Since calcium is an important element in bioactive glass for bone regeneration, this work is trying to find a suitable calcium source for this hybrid system and determine how to incorporate the calcium within the γ-PGA hybrid. Calcium chloride and calcium methoxyethoxide (CME) were tested as calcium sources in this work. CME was found to incorporate into the silica network better than calcium chloride at low temperature.

Polymer/bioactive glass nanocomposites for biomedical applications: A review

Nanoscale bioactive glasses have been gaining attention due to their reported superior osteoconductivity when compared to conventional (micron-sized) bioactive glass materials. The combination of bioactive glass nanoparticles or nanofibers with polymeric systems enables the production of nanocomposites with potential to be used in a series of orthopedic applications, including scaffolds for tissue engineering and regenerative medicine. This review presents the state of art of the preparation of nanoscale bioactive glasses and corresponding composites with biocompatible polymers. The recent developments in the preparation methods of nano-sized bioactive glasses are reviewed, covering sol–gel routes, microemulsion techniques, gas phase synthesis method (flame spray synthesis), laser spinning, and electro-spinning. Then, examples of the preparation and properties of nanocomposites based on such inorganic bionanomaterials are presented, obtained using various polymer matrices, including polyesters such as poly(hydroxybutyrate), poly(lactic acid) and poly(caprolactone), and natural-based polymers such as polysaccharides (starch, chitin, chitosan) or proteins (silk fibroin, collagen). The physico-chemical, mechanical, and biological advantages of incorporating nanoscale bioactive glasses in such biodegradable nanocomposites are discussed and the possibilities to expand the use of these materials in other nanotechnology concepts aimed to be used in different biomedical applications are also highlighted.