Melt-derived Glass Research Articles

Porous Lithium Disilicate Glass-Ceramics Prepared by Cold Sintering Process Associated with Post-Annealing Technique.

Using melt-derived LD glass powders and 5-20 M NaOH solutions, porous lithium disilicate (Li2Si2O5, LD) glass-ceramics were prepared by the cold sintering process (CSP) associated with the post-annealing technique. In this novel technique, H2O vapor originating from condensation reactions between residual Si-OH groups in cold-sintered LD glasses played the role of a foaming agent. With the increasing concentration of NaOH solutions, many more residual Si-OH groups appeared, and then rising trends in number as well as size were found for spherical pores formed in the resultant porous LD glass-ceramics. Correspondingly, the total porosities and average pore sizes varied from 25.6 ± 1.3% to 48.6 ± 1.9% and from 1.89 ± 0.68 μm to 13.40 ± 10.27 μm, respectively. Meanwhile, both the volume fractions and average aspect ratios of precipitated LD crystals within their pore walls presented progressively increasing tendencies, ranging from 55.75% to 76.85% and from 4.18 to 6.53, respectively. Young's modulus and the hardness of pore walls for resultant porous LD glass-ceramics presented remarkable enhancement from 56.9 ± 2.5 GPa to 79.1 ± 2.1 GPa and from 4.6 ± 0.9 GPa to 8.1 ± 0.8 GPa, whereas their biaxial flexural strengths dropped from 152.0 ± 6.8 MPa to 77.4 ± 5.4 MPa. Using H2O vapor as a foaming agent, this work reveals that CSP associated with the post-annealing technique is a feasible and eco-friendly methodology by which to prepare porous glass-ceramics.

Processing and characterization of aligned electrospun gelatin/polycaprolactone nanofiber mats incorporating borate glass (13-93B3) microparticles

Aligned biodegradable fibers incorporating bioactive glass particles are being highly investigated for tissue engineering applications. In this study, 5, 7 and 10 wt% melt-derived 1393B3 borate glass (BG) microparticles (average size: 3.15 µm) were incorporated in 83 wt% polycaprolactone (PCL) and 17 wt% gelatin (GEL) (83PCL/17GEL) solutions to produce aligned electrospun composite nanofiber mats. Addition of 5 wt% BG particles significantly increased the alignment of the nanofibers. However, further incorporation of BG particles led to reduced degree of alignment, likely due to an increase of viscosity. Mechanical tests indicated a tensile modulus and tensile strength of approximately 51 MPa and 3.4 MPa, respectively, for 5 wt% addition of 1393B3 BG microparticles, values considered suitable for soft tissue engineering applications. However, with the increasing amount of 1393B3 BG, the nanofiber mats became brittle. Contact angle was reduced after the addition of 5 wt% of 1393B3 BG particles from ∼45° to ∼39°. Cell culture studies with normal human dermal fibroblast (NHDF) cells indicated that 5 wt% 1393B3 BG incorporated nanofiber mats were cytocompatible whereas higher doping with 1393B3 BGs reduced biocompatibility. Overall, 5 wt% 1393B3 BG doped PCL/GEL nanofiber mats were aligned with high biocompatibility exhibiting desirable mechanical properties for soft tissue engineering, which indicates their potential for applications requiring aligned nanofibers, such as peripheral neural regeneration.

Robocasting of multicomponent sol-gel–derived silicate bioactive glass scaffolds for bone tissue engineering

Robocasting is universally recognized as an affordable and reproducible manufacturing strategy to process glass and glass-ceramic materials in the form of highly ordered porous scaffolds for bone tissue engineering (BTE) applications. Nevertheless, while being widely applied to melt-derived bioactive glasses, this technique was seldom implemented with sol-gel materials due to the intrinsic difficulties in producing suitable inks for extrusion and thus, good printing outcomes. The present experimental work describes a new and relatively easy method to manufacture multicomponent sol-gel bioactive silicate scaffolds (oxide system: 47.5SiO2–20CaO–10MgO–10Na2O-10 K2O-2.5P2O5, mol.%) using dried gels as basic material within the ink composition, which allows by-passing intermediate heat treatments that are usually detrimental to the bioactive potential of the material in physiological environment. The scaffolds, exhibiting a total porosity of 81 vol%, were characterized in terms of morphological-compositional features and bioactivity in simulated body fluid (SBF), paying special attention to ion release and surface modifications occurring upon soaking (apatite-forming ability). The compressive strength of the scaffolds (around 5 MPa) was comparable to that of human cancellous bone. Collectively, the results supported the possibility of using robocast sol-gel–derived scaffolds in BTE approaches. Furthermore, a comparison with robocast scaffolds based on a melt-derived glass with the same composition was reported in order to investigate the effect of the synthesis route on the dissolution behavior and morphological features of the final biomaterials.

Influence of ferric oxide content on performance of ferrosilicate glasses and glass fibers

ABSTRACT The influence of ferric oxide content on the performance of melt-derived ferrimagnetic glass and glass fibers was investigated in this work. Ferrimagnetic glass fibers within ferrosilicate glass system were prepared by spinning method. The effect of ferric oxide content on the microstructure and mechanical properties of the glass fibers were examined. The X-ray diffraction analysis showed the presence of magnetite with spontaneous crystallization for all investigated samples. Transmission electron microscopy (TEM) analysis indicates that the size of magnetite is less than 30 nm in diameter. The surface microstructure, magnetic hysteresis circles, microwave absorption properties, Mössbauer spectra, thermal expansion performance, tensile properties, hardness, and elastic modulus of as-prepared samples were studied in detail.

Sol-gel synthesis of borate-based 13-93B3 bioactive glass powders for biomedical applications

ABSTRACT In this study, borate-based 13–93B3 bioactive glass powders were synthesised through a sol-gel method using tributyl borate as the boron precursor. Any gel formation was not observed in the glass sol during processing and upon the solvent evaporation, a gel-like layer was obtained. Calcinations were performed between 450 °C and 625 °C in air atmosphere to decompose the nitrates leading to the formation of metal oxides in the glass network. Results showed that use of high calcination temperatures to remove the nitrates from precursor materials caused the formation of partially crystalline structures. In vitro mineralisation experiments revealed that synthesised powders calcined at 550 °C converted to hydroxyapatite phase after immersion in simulated body fluid for 1 day. It was concluded that sol-gel- derived 13–93B3 glass powders have enhanced bioactivity and can be an alternative to conventional melt-derived borate-based bioactive glasses synthesised at much higher temperatures.

13-93B3 Bioactive glasses containing Ce3+, Ga3+ and V5+: dose rate and gamma radiation characteristic for medical purposes

In this study, dose rates and radiation attenuation features of a group of fabricated bioactive glasses were investigated. The borate-based 13-93B3 bioactive glass powders (B3) containing cerium (III), gallium (III) or vanadium (IV) were prepared by melting a homogenized mixture of reagent-grade CaCO3, Na2CO3, MgCO3, K2CO3, H3BO3, CaHPO4.2H2O, Ga2O3, V2O5 or Ce(CH3CO2)3, and disc-shaped scaffolds were prepared by die pressing. Bioactive glasses were modelled by using MCNPX (version 2.7.0) general-purpose Monte Carlo code. A gamma-ray transmission set-up was utilized for determination of mass attenuation coefficients. The obtained coefficients were used for determination of other essential attenuation properties. Finally, exposure (EBF) and energy absorption (EABF) build-up factors were determined. Although the chemical structure of the additive material in bioactive glasses is identical, it can be inferred that the chemical structure of the additive is closely linked to the radiation attenuation characteristics of the bioactive glasses. Results also revealed that, although the bulk densities of the disc-shaped bioactive glass samples were lower than the measured true density values of the melt-derived glass powders due to porosity concerns, they exhibited radiation shielding effect. Findings of the study may be useful in understanding the radiation shielding characteristics of the bioactive glass scaffolds fabricated by powder processing. It can be concluded that outcomes of recent investigation can be useful during the evaluation of potential interactions between the bioactive glasses and medical radiation in the body.

Bioactivity of microporous borate glass-ceramics prepared from solution and derived glasses

Microporous borate compositions based on the formula xB2O3•(100–x)(0.5CaO•0.45Na2O•0.05P2O5) (x = 56.1 and 51.1 mol%) have been prepared from solution. The dried products were subjected to heat-treatment at 600 and 700 °C for 3 h to obtain borate glass-ceramics with scaffold-like structure. Bioactivity and degradation were tested in simulated body fluid (SBF) at 37 °C for different time intervals. Scanning (SEM) and transmission (TEM) electron microscopy, infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to examine the correlation between bioactivity and microstructure. Results indicated that the type and concentration of crystalline CaNaB5O9 and CaNa3B5O10 phases, in addition to concentration of bridging and non-bridging oxygen atoms, are the factors affecting the apatite forming ability and composition degradation. XRD and SEM results showed that the as-prepared compositions and those heat-treated at 600 and 700 °C are crystalline matrices, while TEM-EDP of selected region exhibited halo diffuse intensity with clear bright spots. These features indicate that the crystalline phases are dispersed in amorphous phase. After immersion in SBF, TEM-EDP proved that the crystalline hydroxyapatite (HA) phase was formed on amorphous phase. The type of product after reaction in SBF is influenced by the nature of borate network. For melt-derived borate glasses, hydrous species of B(OH)3 and amorphous calcium phosphate are formed. Microporous borate glass-ceramics exhibited a good in vitro bioactive response through the formation of hydroxyapatite, except when the matrix is rich in CaNa3B5O10 phase. The results of this study suggest that the solution-method can be used to prepare microporous bioactive borate glass-ceramics, such as three-dimensional porous scaffolds, which are of particular interest for the clinical application in bone regeneration.

Comparison Between Bioactive Sol-Gel and Melt-Derived Glasses/Glass-Ceramics Based on the Multicomponent SiO2-P2O5-CaO-MgO-Na2O-K2O System.

Bioactive sol-gel glasses are attractive biomaterials from both technological and functional viewpoints as they require lower processing temperatures compared to their melt-derived counterparts and exhibit a high specific surface area due to inherent nanoporosity. However, most of these materials are based on relatively simple binary or ternary oxide systems since the synthesis of multicomponent glasses via sol-gel still is a challenge. This work reports for the first time the production and characterization of sol-gel materials based on a six-oxide basic system (SiO2–P2O5–CaO–MgO–Na2O–K2O). It was shown that calcination played a role in inducing the formation of crystalline phases, thus generating glass-ceramic materials. The thermal, microstructural and textural properties, as well as the in vitro bioactivity, of these sol-gel materials were assessed and compared to those of the melt-derived counterpart glass with the same nominal composition. In spite of their glass-ceramic nature, these materials retained an excellent apatite-forming ability, which is key in bone repair applications.

Synthesis of bioactive material by sol–gel process utilizing polymorphic calcium carbonate precipitate and their direct and indirect in-vitro cytotoxicity analysis

Abstract To mitigate the rising level of CO2, biological method of CO2 sequestration is one of the effective methods. Chemolithotrophic microbes are able to fix atmospheric CO2 and precipitated polymorphic minerals like calcite, vaterite and aragonite. Based on this, bioactive glass was synthesized by sol–gel process using polymorphic calcium carbonate mineral precipitated by chemolithotrophic Serratia sp. ISTD04. Characterization of bioactive material and its bioactivity was evaluated by SEM, EDX, FT-IR, XRD, ICP-MS. SEM analysis revealed biomaterial showing more bioactivity due to deposition of smaller particle like appearance throughout the surface. FT-IR analysis of sintered and immersed bioactive material indicated presence of O-Ca-O, O-Si-O and Si-O-Si functional group. The XRD analysis indicated important features similar to melt-derived Na2 O-containing glass ceramics like formation of crystalline phase Na2Ca2Si3O9. Further in-vitro study was performed in simulated body fluid (SBF) and on osteosarcoma cell line, confirmed that material and their supernatant did not reflect any cytotoxicity.

Robocasting of SiO2-Based Bioactive Glass Scaffolds with Porosity Gradient for Bone Regeneration and Potential Load-Bearing Applications.

Additive manufacturing of bioactive glasses has recently attracted high interest in the field of regenerative medicine as a versatile class of fabrication methods to process bone substitute materials. In this study, melt-derived glass particles from the SiO2-P2O5-CaO-MgO-Na2O-K2O system were used to fabricate bioactive scaffolds with graded porosity by robocasting. A printable ink made of glass powder and Pluronic F-127 (binder) was extruded into a grid-like three-dimensional structure with bimodal porosity, i.e., the inner part of the scaffold had macropores with smaller size compared to the periphery. The crystallization behavior of the glass powder was studied by hot-stage microscopy, differential thermal analysis, and X-ray diffraction; the scaffolds were sintered at a temperature below the onset of crystallization so that amorphous structures could be obtained. Scaffold architecture was investigated by scanning electron microscopy and microtomographic analysis that allowed quantifying the microstructural parameters. In vitro tests in Kokubo’s simulated body fluid (SBF) confirmed the apatite-forming ability (i.e., bioactivity) of the scaffolds. The compressive strength was found to slightly decrease during immersion in SBF up to 4 weeks but still remained comparable to that of human cancellous bone. The pH and concentration of released ions in SBF were also measured at each time point. Taken together, these results (favorable porosity, mechanical strength, and in vitro bioactivity) show great promise for the potential application of these robocast scaffolds in bone defect repair.

Influence of zinc ions on structure, bioactivity, biocompatibility and antibacterial potential of melt-derived and gel-derived glasses from CaO-SiO2 system

Several different compositions of zinc-containing glasses in the CaO-SiO2 system were obtained by both traditional melting technique and the sol-gel method. The influence of zinc ions addition in the glass composition was evaluated using different spectroscopic methods (FTIR and 29Si MAS-NMR). It was demonstrated that ZnO has a significant effect on glass structure and, as a consequence, on thermal properties, texture and bioactivity. EDX and ICP data showed that zinc ions reduce glass bioactivity and incorporate in the newly forming HCA layer. Evaluation of the in vitro biocompatibility of the obtained materials was performed by indirect tests using MG-63 osteoblast-like cells. All samples were found to be biocompatible and zinc ions enhanced the cell viability. Antibacterial tests against gram-negative (E. coli) and gram-positive bacteria (S. aureus) were carried out to evaluate the antibacterial potential of the zinc-doped glasses.

Effect of synthetic amorphous calcium phosphate nanoparticles on the physicochemical and biological properties of resin-modified glass ionomer cements

The aim of this study was to find an optimum dose of the synthetic amorphous calcium phosphate (ACP) nanoparticles to be incorporated in resin-modified glass ionomer cements (RMGICs) for triggering the release of PO43−/Ca2+, alkaline phosphatase (ALP) activity and osteogenic differentiation of mesenchymal stem cells (hMSCs) without significantly affecting the essential properties of the cements. RMGICs were formulated from the powder composed of melt-derived strontium fluoro-aluminosilicate glass (SFAG) and synthetic ACP nanoparticles (0–20 wt%), as well as commercial polyalkenoic acid liquid. The effect of ACP incorporation on the workability, microstructure, Ca2+/PO43−/F− ion release and compressive strength was investigated. The response of hMSCs to the optimized cements was assessed by MTT cytotoxicity, ALP activity, and staining tests. The working time of the formulated RMGICs decreased significantly upon increase of ACP content from 5 to 20%. ACP (5%)–incorporated RMGICs showed improved photopolymerization and setting. An insignificant reduction was recorded in the compressive strength of RMGICs with addition of 1.5–5% ACP. The fluoride release didn't significantly decrease due to addition of 5% ACP. Upon incorporating 5% ACP, the biocompatibility of RMGICs rose to about 20%. In addition, ALP activity and osteogenic differentiation of hMSCs noticeably increased after exposure to ACP–incorporated RMGIC. ACP (5%)–incorporated RMGICs could be promising candidates for both restorative and regenerative dentistry owing to the optimum mechanical strength, prolonged ion release, and their effective role in the cell differentiation and biomineralization demanded for pulp regeneration.

Structural characterization and evaluation of antibacterial and angiogenic potential of gallium-containing melt-derived and gel-derived glasses from CaO-SiO2 system

Gallium-containing glasses were synthesized by the sol-gel and traditional melting techniques to obtain bioactive amorphous materials with antibacterial and angiogenic properties. The influence of gallium ion addition on glass structure was described using two spectroscopic methods (FTIR and 29Si MAS NMR). DSC (Differential Scanning Calorimetry) analysis revealed differences in thermal properties, which were explained by varying ionicity of the chemical bonds. The study shows that gallium ions addition causes a significant difference in glass structure and, as a consequence, in thermal properties, microstructure, and biological response. Dissolution products of the researched glasses incubated in SBF and distillated water were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). To perform the indirect in vitro biocompatibility studies, human osteoblast-like cells (MG-63) were cultivated in the supernatants, which were obtained by incubation of the glass powders in the cell culture medium. The evaluation of the potential angiogenic properties of gallium-doped glasses was performed by measuring the release of human vascular endothelial growth factor (VEGF) from MG-63 cells. Dissolution products of the all samples were tested for antibacterial activity against gram-negative (E. coli) and gram-positive bacteria (S. aureus).

Electrospun poly-l-lactic acid nanofibers decorated with melt-derived S53P4 bioactive glass nanoparticles: The effect of nanoparticles on proliferation and osteogenic differentiation of human bone marrow mesenchymal stem cells in vitro

S53P4 bioactive glass nanoparticles (BGn) were prepared by the melting-quenching method at 1400 °C followed by ball milling. The prepared glass nanoparticles were used for surface decoration of poly-l-lactic acid (PLLA) nanofibers fabricated by electrospinning method. The microstructure, morphology and chemical functional groups of the nanomaterials were characterized by XRD, FESEM, and FTIR techniques. The results confirmed the successful synthesis of amorphous glass nanoparticles with the diameter ranged from ~ 100 to 800 nm and PLLA nanofibers with an average diameter of 500 nm. PLLA/BGn nanocomposites showed a uniform distribution of the BGn on the surface of PLLA nanofibers. The growth, viability, and proliferation of the cultured human bone marrow mesenchymal stem cells (hMSCs) on the prepared nanomaterials were examined using various biological assays, including MTT cytotoxicity, ALP activity, calcium biomineralization, Alizarin red staining, and gene expression. The biological results clearly showed that the growth, proliferation and osteogenic ability of hMSCs were significantly improved due to the surface modification of PLLA nanofibers with BGn. It was concluded that the 3D structure, optimum porosity and balanced dissolution rate of PLLA/BGn nanocomposites led to the promoted cellular activity.

Preparation and mineralization of 13-93 bioactive glass-containing electrospun poly-epsilon-caprolactone composite nanofibrous mats

In this study, silicate- based 13-93 bioactive glass (BG) /poly-ε-caprolactone (PCL) nanocomposite fiber mats were fabricated through electrospinning. To prepare composites, amorphous electrospun bioactive glass nanofibers (BGFs) or melt-derived microscale bioactive glass particles (BGPs) were incorporated into the PCL matrix. In vitro mineralization ability of the prepared fibrous mats was assessed in simulated body fluid under static conditions. The results revealed that it is possible to prepare bead-free continuous nanofibers using PCL-acetone solution at specified PCL concentrations (8 and 10 wt%). Nanofibers with almost uniform diameters were produced using 10 wt% PCL solution. Incorporation of BG in the form of particle or fiber into the PCL matrix was made between 1 wt% and 10 wt%. The results showed that the diameter of BGP-containing composite fibers was higher compared to BGF-containing composite scaffolds. The addition of BG to the PCL matrix both in the form of powder and fiber enhanced hydroxyapatite formation in the fibrous scaffolds. The amount of calcium phosphate–based material formation was higher in glass particle–containing samples compared to glass fiber–containing PCL scaffolds. Additionally, the degradation rate in phosphate buffer and silicium ion release amount of BGP-containing PCL fibers was higher compared to BGF-containing PCL fibers. It was concluded that fibrous composite scaffolds prepared in this study could have potential in tissue engineering applications.

An investigation on injectable composites fabricated by 45S5 bioactive glass and gum tragacanth: Rheological properties and in vitro behavior

The injectable composites were formulated from melt-derived 45S5 bioactive glass powder and gum tragacanth. The effect of the tragacanth (2 and 4 w/v%) and powder to liquid ratio (P/L= 1.5 to 2.5) on rheological properties, injectability, degradation, swelling, and bioactivity the composites were studied. With increasing the P/L ratio and tragacanth concentration, the force required for injection of the composites is increased. However, the formulated composites show maximum injection force of 15 N, which seems to be appropriate for surgical purposes. The formulated composites indicate positive thixotropic behavior, whereas increasing tragacanth from 2% to 4% lead to deteriorating its behavior. Moreover, thecomposites formulated by 2% tragacanth show much more resistance against degradation and swelling. The bioactivity analyze confirms the formation of flake-like apatite nanostructures on the surface of nanocomposites in initial days of immersion into the SBF solution.

Structural and microstructural comparison of bioactive melt-derived and gel-derived glasses from CaO-SiO2 binary system

Two glasses from CaO-SiO2 binary system were obtained by sol-gel and melting techniques. The effect of two different glass obtaining methods was investigated using X-ray diffraction, FTIR, Raman and 29Si MAS NMR spectroscopic methods. The measurements revealed significant differences in the glasses structure. Although both glasses were fully amorphous, the gel-derived glass had a more polymerized structure compared to the melt-derived one. The studied glasses were characterized by BET analysis to provide information about specific surface area of the obtained materials. Apart from microstructural evaluation, thermal properties and in vitro bioactivity study of all glasses were conducted to demonstrate differences in performance of the samples. The formation process of hydroxycarbonate apatite (HCA) layer was investigated using inductively coupled plasma mass spectrometry (ICP-MS) and structural studies.

Effect of temperature on mechanical and bioactive properties of glass-ceramics

Melt-derived glass ceramics were prepared having the following chemical composition 33SiO2-21CaO-32.5Na2O-12P2O5-1.5MgO (mol %). Samples were sintered at three different temperatures (750, 800, and 850 °C). Thermal, structural, and bioactivity analyses were carried out using TGA-DSC, XRD, and in vitro immersion tests, respectively. XRD results indicated that CaSiO3 was the major phase while Na2Ca2Si3O9 was the minor phase in a glass matrix. The crystallite size and degree of crystallization increased with sintering temperature. Additionally, SEM images showed grain growth and reduction of pores with increasing sintering temperature. The bioactivity of the specimens were assessed by XRD; all specimens exhibited hydroxyapatite phase on their surfaces after immersion in a simulated body fluid, indicating the bioactive nature of the material. Further, the sample sintered at 750 °C was observed to be more bioactive as indicated by crystallization of Ca10(PO4)6(OH)2 on its surface. These results indicate that sintering at high temperature increases the crystallinity, microhardness and chemical stability of this bioactive glass ceramic.

Sol–gel-derived manganese-releasing bioactive glass as a therapeutic approach for bone tissue engineering

Sol–gel processing allows the production of bioactive glasses (BG) with flexible compositions and the incorporation of different metallic ions with therapeutic benefits into the glass network. Manganese is among several previously studied therapeutically beneficial ions and has been shown to favour osteogenic differentiation, in addition to playing an important role in cell adhesion. The incorporation of Mn into bioactive glasses for tissue engineering has been previously conducted using the conventional melting route, whereas the sol–gel route has not yet been explored. Sol–gel technology has great versatility, allowing the preparation of BG with various compositions, sizes, morphologies and a large surface area that could provide improved cellular responses and enhanced bioactivity when compared to melt-derived glasses. In this context, this work developed new compositions of sol–gel bioactive glasses (on the SiO2–P2O5–CaO–MnO system) and explored the effects of incorporating MnO on the structure, texture, in vitro bioactivity and cytocompatibility of these materials. Our results show that Mn-containing bioactive glasses present an amorphous character, high surface area and mesoporous structure. The formation of a hydroxycarbonate apatite (HCA) layer after immersion in simulated body fluid (SBF) revealed the high bioactivity of the glasses. Ion release evaluation indicated that the Si, Ca, P and Mn release levels could be adjusted within therapeutic limits, and cytotoxic analysis demonstrated that the ionic products of all samples generated a cell-friendly environment. Therefore, Mn incorporation into the bioactive glass network appears to be a potential strategy to develop superior materials with sustained ion release for tissue engineering.

Composite Biomaterials Based on Sol-Gel Mesoporous Silicate Glasses: A Review.

Bioactive glasses are able to bond to bone and stimulate the growth of new tissue while dissolving over time, which makes them ideal materials for regenerative medicine. The advent of mesoporous glasses, which are typically synthesized via sol-gel routes, allowed researchers to develop a broad and versatile class of novel biomaterials that combine superior bone regenerative potential (compared to traditional melt-derived glasses) with the ability of incorporating drugs and various biomolecules for targeted therapy in situ. Mesoporous glass particles can be directly embedded as a bioactive phase within a non-porous (e.g., microspheres), porous (3D scaffolds) or injectable matrix, or be processed to manufacture a surface coating on inorganic or organic (macro)porous substrates, thereby obtaining hierarchical structures with multiscale porosity. This review provides a picture of composite systems and coatings based on mesoporous glasses and highlights the challenges for the future, including the great potential of inorganic–organic hybrid sol-gel biomaterials.