Synthesis, characterization and in vitro bioactivity of sol-gel-derived SiO2–CaO–P2O5–MgO bioglass

Devitrite (Na2Ca3Si6O16) phase dominated nanostructured 45S5 bioactive glass: exploring its structural and biological properties

This research study is primarily centred around calcination temperature and time influence on phase formation in bioactive glasses (BGs). In the present study, BG with a nominal composition of 45S5 was synthesized through the sol-gel process. The developed BGs then underwent heat treatment for various sintering durations and temperatures. X-ray diffraction (XRD) patterns of the BGs reveals that the sintering process led to the crystallization of both devitrite (Na2Ca3Si6O16) and combeite (Na2Ca2Si3O9) phases. The field emission scanning electron microscopy study divulges morphological alterations, from sheet-like to rod-like structures to eventually transforming into spherical and sheet-like structures. The surface area and Type-IV mesoporous porosity were validated through Brunauer Emmett Teller analysis, highlighting a notable increase in pore volume and mechanical strength at a lower sintering temperature.In vitroapatite formation was carried out in Hank's balance salt in order to evaluate the bioactivity of the glass. After 7 d of immersion in simulated body fluid (SBF), XRD patterns and scanning electron microscopy micrographs results showed that formation of hydroxyapatite layer on the surface of the BGs. The BG compatibility with erythrocytes (red blood cells) was also studied, and the results revealed that there was only a low 2% lysis, showing good hemocompatibility. The drug loading and release behaviour of the BGs was studied in thein vitroanalysis. The findings showed a high drug encapsulation effectiveness of up to 90% and continuous drug release from the BGs for 24 h. The materials biocompatibility was unambiguously confirmed by cytocompatibility and proliferation studies. This study provides compelling evidence for the exceptional efficacy and promise of the distinct 45S5 BGs in advancing the field of regenerative medicine.

Drug kinetics and antimicrobial properties of quaternary bioactive glasses 81S(81SiO2-(16-x)CaO-2P2O5-1Na2O-xMgO); an in-vitro study

Bioactive glasses have recently been attracted to meet the challenge in bone tissue regeneration, repair, healing, dental implants, etc. Among the conventional bio-glasses, a novel quaternary mesoporous nano bio-glass with composition 81S(81SiO2-(16-x)CaO-2P2O5-1Na2O-xMgO) (x = 0, 1.6, 2.4, 4 and 8 mol%) employing Stober's method has been explored for examining the above potential application through in-vitro SBF assay, MTT assay, antimicrobial activity and drug loading and release ability. With increasing the MgO concentration up to 4 mol%, from in-vitro SBF assay, we observe that HAp layer develops on the surface of the nBGs confirmed from XRD, FTIR and FESEM. MTT assay using MG-63 cells confirms the biocompatibility of the nBGs having cell viability >225 % for MGO_4 after 72 h which is more than the clinically used 45S5 bio-glass. We have observed cell viability of >125 % even after 168 h. Moreover, MGO_4 is found to restrict the growth of E. coli by 65 % while S. aureus by 75 %, confirming the antimicrobial activity. Despite an increase in the concentration of magnesium, nBGs are found to be non-toxic towards the RBCs up to 4 mol% of MgO while for 8 %, the hemolysis percentage is >6 % which is toxic. Being confirmed MGO_4 nBG as a bioactive material, various concentrations of drug (Dexamethasone (DEX)) loading and release kinetics are examined. We show that 80 % of loading in case of 10 mg-ml-1 and 70 % of cumulative release in 100 h. The mesoporous structure of MGO_4 having an average pore diameter of 5 nm and surface area of 216 m2 g-1 confirmed from BET supports the loading and release kinetics. We conclude that the quaternary MGO_4 nBG may be employed effectively for bone tissue regeneration due to its high biocompatibility, excellent in-vitro cell viability, antimicrobial response and protracted drug release.

Effects of cerium-doped bioactive glass incorporation on an alginate/gelatin scaffold for bone tissue engineering: In vitro characterizations

Bioactive glasses (BGs) have been extensively employed in treating bone defects due to their capacity to bond and integrate with hard and soft tissues. To promote their characteristics, BGs are doped with therapeutic inorganic ions; Among these, Cerium (Ce) is of special attention because of its material and biological properties. This study aimed to investigate the effects of the addition of Ce to BG on the physicochemical and biological properties of the alginate/gelatin (Alg-Gel) scaffold compared with a similar scaffold that only contains BG45S5. The scaffolds were characterized for their biocompatibility using human bone marrow-derived mesenchymal stem cells (hBM-MSCs) by MTT analysis. The osteogenic differentiation of hBM-MSCs cultured on the scaffolds was assessed by evaluating the alkaline phosphatase (ALP) activity and the expression of osteogenic-related genes. Scanning electron microscopy of the prepared scaffolds showed an interconnected porous structure with an average diameter of 212-272 μm. The Young's modulus of the scaffolds significantly increased from 13 ± 0.82 MPa for Alg-Gel to 91 ± 1.76 MPa for Alg-Gel-BG/Ce. Ce doping improved the osteogenic differentiation of hBM-MSCs and ALP secretion compared to the other samples, even without adding an osteogenic differentiation medium. The obtained results demonstrated the biocompatibility and osteo-inductive potentials of the Alg-Gel-BG/Ce scaffold for bone tissue engineering.

To study the synthesis and characterization of SrO-MgO-SiO2 system in biological and dielectric applications

Ternary ceramic samples comprising SrO-MgO-SiO2 with varying element concentrations were synthesized using the solid-state method and sintered at 800°C. To characterize the properties of the samples, several analysis techniques were employed. X-ray Diffraction (XRD) was utilized for structural analysis, FTIR spectroscopy was used to identify bonds, SEM provided morphological analysis, biocompatibility was assessed through Vitro testing, microhardness was evaluated using Vickers testing, and dielectric analysis was performed to investigate electrical properties. The XRD spectra confirmed the presence of a ternary phase known as Magnesium Strontium Di-silicate [MgSr2Si2O7], with no impurity peaks detected. FTIR spectroscopy indicated the formation of Magnesium silicate, displaying vibrational bands corresponding to SiO4 and MgO, which further confirmed the existence of MgSr2Si2O7 in the samples. The Vitro test results revealed that all samples exhibited biocompatible behavior, with moderate pH and weight loss. SEM images provided insights into the morphology of the system and confirmed the development of an appetite layer on the sample surfaces. The particle size of the samples was measured to be approximately 116.48±9 nm. Vickers hardness testing yielded microhardness values ranging from 378.1 to 400.2 HV. Dielectric constant measurements demonstrated that the AC conductivity of the SrO-MgO-SiO2 system increased as the percentage of Mg doping increased.

Chitosan-Polyvinyl Alcohol Nanocomposites for Regenerative Therapy

Tissue accidents provide numerous pathways for pathogens to invade and flourish, causing additional harm to the host tissue while impeding its natural healing and regeneration. Essential oils (EOs) exhibit rapid and effective antimicrobial properties without promoting bacterial resistance. Clove oils (CEO) demonstrate robust antimicrobial activity against different pathogens. Chitosan (CS) is a natural, partially deacetylated polyamine widely recognized for its vast antimicrobial capacity. In this study, we present the synthesis of four membrane formulations utilizing CS, polyvinyl alcohol (PVA), and glycerol (Gly) incorporated with CEO and nanobioglass (n-BGs) for applications in subdermal tissue regeneration. Our analysis of the membranes' thermal stability and chemical composition provided strong evidence for successfully blending polymers with the entrapment of the essential oil. The incorporation of the CEO in the composite was evidenced by the increase in the intensity of the band of C-O-C in the FTIR; furthermore, the increase in diffraction peaks, as well as the broadening, provide evidence that the introduction of CEO perturbed the crystal structure. The morphological examination conducted using scanning electron microscopy (SEM) revealed that the incorporation of CEO resulted in smooth surfaces, in contrast to the porous morphologies observed with the n-BGs. A histological examination of the implanted membranes demonstrated their biocompatibility and biodegradability, particularly after a 60-day implantation period. The degradation process of more extensive membranes involved connective tissue composed of type III collagen fibers, blood vessels, and inflammatory cells, which supported the reabsorption of the composite membranes, evidencing the material's biocompatibility.

Evaluation of the time-dependent osteogenic activity of glycerol incorporated magnesium oxide nanoparticles in induced calvarial defects

Introduction

Magnesium-based biomaterials have been explored for their potential as bone healing materials, as a result of their outstanding biodegradability and biocompatibility. These characteristics make magnesium oxide nanoparticles (MgO NPs) a promising material for treating bone disorders. The purpose of this investigation is to assess the osteogenic activity of newly-developed locally administered glycerol-incorporated MgO NPs (GIMgO NPs) in rabbits' calvarial defects.

Materials and methods

Characterization of GIMgO was done by X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Bilateral calvarial defects were created in eighteen New Zealand Rabbits, of which they were divided into 3 groups with time points corresponding to 2, 4, and 6 weeks postoperatively (n = 6). One defect was implanted with absorbable gel foam impregnated with GIMgO NPs while the other was implanted with gel foam soaked with glycerol (the control). The defects were assessed using histological, Micro-Computed Tomography (Micro-CT), and histometric evaluation.

Results

The characterization of the GIMgO nanogel revealed the presence of MgO NPs and glycerol as well as the formation of the crystalline phase of the MgO NPs within the nanogel sample. The histological and micro-CT analysis showed time-dependent improvement of healing activity in the calvarial defects implanted with GIMgO NPs when compared to the control. Furthermore, the histometric analysis demonstrated a marked increase in the total area of new bone, connective tissue, new bone area and volume in the GIMgO NPs implanted site. Statistically, the amount of new bone formation was more significant at 6 weeks than at 2 and 4 weeks postoperatively in the calvarial defects implanted with GIMgO NPs as compared to the control.

Conclusion

The locally applied GIMgO NPs demonstrated efficacy in promoting bone formation, with more significant effects observed over an extended period. These findings suggest its suitability for clinical use as a therapeutic alternative to enhance bone healing.

A Review on the Recent Advancements on Therapeutic Effects of Ions in the Physiological Environments

This review focuses on the therapeutic effects of ions when released in physiological environments. Recent studies have shown that metallic ions like Ag+, Sr2+, Mg2+, Mn2+, Cu2+, Ca2+, P+5, etc., have shown promising results in drug delivery systems and regenerative medicine. These metallic ions can be loaded in nanoparticles, mesoporous bioactive glass nanoparticles (MBGNs), hydroxyapatite (HA), calcium phosphates, polymeric coatings, and salt solutions. The metallic ions can exhibit different functions in the physiological environment such as antibacterial, antiviral, anticancer, bioactive, biocompatible, and angiogenic effects. Furthermore, the metals/metalloid ions can be loaded into scaffolds to improve osteoblast proliferation, differentiation, bone development, fibroblast growth, and improved wound healing efficacy. Moreover, different ions possess different therapeutic limits. Therefore, further mechanisms need to be developed for the highly controlled and sustained release of these ions. This review paper summarizes the recent progress in the use of metallic/metalloid ions in regenerative medicine and encourages further study of ions as a solution to cure diseases.

Sol-Gel ceramic glazes with photocatalytic activity

A frit is a glassy ceramic composition that has been fused, quenched, and granulated. A single frit or a mixture of frits and ceramic materials forms a ceramic glaze. The purpose of this pre-fusion is to render any soluble and/or toxic components insoluble by rendering it inert in a glassy composition with silica and other added oxides. The ceramic glaze dispersed in water (ceramic slip) is deposited on a ceramic body and fired for waterproofing and aesthetic purposes. Multicomponent frits (zinc-potassium borosilicate system) with similar behavior to conventional ceramic frits for single-firing ceramic glazes ("monoporosa" glazes fired at 1080 °C) were prepared by Sol-Gel methods (monophasic and polyphasic gels) avoiding the pre-fusion and characterized as photocatalytic agents (showing high degradation activity on Orange II). The effect of doping with bandgap modifiers (V₂O₅, Sb₂O₅ and SnO₂) and also with devitrification agents (ZrO₂ to crystallize zircon, Al₂O₃ to anorthite, Mo₂O₃ to powellite and ZnO to gahnite ZnAl₂O₄) were analyzed. Multicomponent frits (zinc-potassium borosilicate system) with similar behavior to conventional ceramic frits for single-firing glazes (1080 °C) prepared by Sol-Gel methods (monophasic and polyphasic gels), without pre-fusion, shows photocatalytic activity.

Effect of Ce-doped bioactive glass/collagen/chitosan nanocomposite scaffolds on the cell morphology and proliferation of rabbit’s bone marrow mesenchymal stem cells-derived osteogenic cells

Background

Cerium-containing materials have wide applications in the biomedical field, because of the mimetic catalytic activities of cerium. The study aims to deeply estimate the biocompatibility of different scaffolds based on Ce-doped nanobioactive glass, collagen, and chitosan using the first passage of rabbit bone marrow mesenchymal stem cells (BM-MSCs) directed to osteogenic lineage by direct and indirect approach. One percentage of glass filler was used (30 wt. %) in the scaffold, while the percentage of CeO₂ in the glass was ranged from 0 to 10 mol. %. Cytotoxicity was evaluated by monitoring of cell morphological changes and reduction in cell proliferation activity of BMMSCs maintained under osteogenic condition using proliferation assays, MTT assay for the direct contact of cells/scaffolds twice in a week, trypan blue and hemocytometer cell counting for indirect contact of cells/scaffolds extracts at day 7. Cell behaviors growth, morphology characteristics were monitored daily under a microscope and cell counting were conducted after 1 week of the incubation of the cells with the extracts of the four composite scaffolds in the osteogenic medium at the end of the week.

Results

Showed that at 24 h after direct contact with composite scaffold, all scaffolds showed proliferation of cells > 50% and increased in cell density on day 7. The scaffold of the highest percentage of CeO₂ in bioactive glass nanoparticles (sample CL/CH/C10) showed the lowest inhibition of cell proliferation (< 25%) at day 7. Moreover, the indirect cell viability test showed that all extracts from the four composite scaffolds did not demonstrate a toxic effect on the cells (inhibition value < 25%).

Conclusion

The addition of CeO₂ to the glass composition improved the biocompatibility of the composite scaffold for the proliferation of rabbit bone marrow mesenchymal stem cells directed to osteogenic lineage.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43141-022-00302-x.

Ion-doped mesoporous bioactive glass: preparation, characterization, and applications using the spray pyrolysis method

Biotechnology is used extensively in medical procedures, dentistry, statures, biosensors, bio electrodes, skin substitutes, and medicine delivery systems. Glass is biocompatible and can be used in permanent implantation applications without risk. The porosity of BG matrixes, combined with their huge specific surface area, greatly aids the formation of hydroxyl carbonate apatite. Zn-Doped bioglass can be made in the lab in a variety of ways, depending on how it will be used in medical treatment. The melt-quenching technique, spray pyrolysis method, sol-gel process for BG fabrication, spray drying method, and modified Stöber method are examples of such strategies. Spray pyrolysis is a comprehensive approach that is an undeniably versatile and effective material synthesis technology. It is a low-cost, non-vacuum method for producing materials in the form of powders and films that may be deposited on a variety of substrates, and is a straightforward method to adapt for large-area deposition and industrial production processes. For better utility in medical care, MBG fabricated in the laboratory should be characterized using various characterization methods such as SEM, TEM, BET, and XRD.

The effect of vanadium ferrite doping on the bioactivity of mesoporous bioactive glass-ceramics

Bioactive glasses are highly reactive surface materials synthesized by melting or sol–gel techniques. In this study, mesoporous bioactive glass-ceramics doped with different amounts of vanadium and iron ((60−(x + y)) SiO₂–36CaO–4P₂O₅–xV₂O₅–yFe₂O₃, x and y between 0, 5 and, 10 mole%) were synthesized using a sol–gel method. Then, their effects on particle morphology and the biomineralization process were examined in simulated body fluid (SBF). N2 adsorption isotherm analysis proved that the samples have a mesoporous structure. In addition, the Fourier-transform infrared spectroscopy (FTIR) spectra of the samples after soaking in SBF for various periods (7, 14, and 21 days) confirmed the presence of new chemical bonds related to the apatite phase, which is in accordance with scanning electron microscopy (SEM) observations. X-ray diffraction (XRD) patterns of the samples after SBF soaking showed that lower amounts of vanadium and iron were associated with the formation of a stable and more crystalline phase of hydroxyapatite. The MTT results showed that the cell viability of mesoporous bioactive glass containing 5% V₂O₅ remains more than 90% over 7 days, which indicates the biocompatibility of the samples. To conclude, further studies on these formulations are going to be carried out in future investigations for chemohyperthermia application.

Bioactive glasses are highly reactive surface materials synthesized by melting or sol–gel techniques.

An In Vitro Evaluation of the Biological and Osteogenic Properties of Magnesium-Doped Bioactive Glasses for Application in Bone Tissue Engineering

Magnesium (Mg2+) is known to play a crucial role in mineral and matrix metabolism of bone tissue and is thus increasingly considered in the field of bone tissue engineering. Bioactive glasses (BGs) offer the promising possibility of the incorporation and local delivery of therapeutically active ions as Mg2+. In this study, two Mg2+-doped derivatives of the ICIE16-BG composition (49.46 SiO2, 36.27 CaO, 6.6 Na2O, 1.07 P2O5, 6.6 K2O (mol%)), namely 6Mg-BG (49.46 SiO2, 30.27 CaO, 6.6 Na2O, 1.07 P2O5, 6.6 K2O, 6.0 MgO (mol%) and 3Mg-BG (49.46 SiO2, 33.27 CaO, 6.6 Na2O, 1.07 P2O5, 6.6 K2O, 3.0 MgO (mol%)) were examined. Their influence on viability, proliferation and osteogenic differentiation of human mesenchymal stromal cells (MSCs) was explored in comparison to the original ICIE16-BG. All BGs showed good biocompatibility. The Mg2+-doped BGs had a positive influence on MSC viability alongside with inhibiting effects on MSC proliferation. A strong induction of osteogenic differentiation markers was observed, with the Mg2+-doped BGs significantly outperforming the ICIE16-BG regarding the expression of genes encoding for protein members of the osseous extracellular matrix (ECM) at certain observation time points. However, an overall Mg2+-induced enhancement of the expression of genes encoding for ECM proteins could not be observed, possibly due to a too moderate Mg2+ release. By adaption of the Mg2+ release from BGs, an even stronger impact on the expression of genes encoding for ECM proteins might be achieved. Furthermore, other BG-types such as mesoporous BGs might provide a higher local presence of the therapeutically active ions and should therefore be considered for upcoming studies.

Physicochemical and Biological Properties of Mg-Doped Calcium Silicate Endodontic Cement

Calcium silicate-based cement has been widely used for endodontic repair. However, it has a long setting time and needs to shorten setting time. This study investigated the effects of magnesium (Mg) ion on the setting reaction, mechanical properties, and biological properties of calcium silicate cement (CSC). Sol-gel route was used to synthesize Mg ion-doped calcium silicate cement. Synthesized cement was formulated with the addition of different contents of Mg ion, according to 0, 1, 3, 5 mol% of Mg ion-doped calcium silicate. The synthesized cements were characterized with X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). We also evaluated the physicochemical and biological properties of cement, such as the setting time, compressive strength, micro-hardness, simulated body fluid (SBF) immersion, cytotoxicity, and cell differentiation tests. As a result, the Mg ion improves the hydration properties of calcium silicate cement, and the setting time is reduced by increasing the amounts of Mg ion. However, the mechanical properties deteriorated with increasing Mg ion, and 1 and 3 mol% Mg-doped calcium silicate had appropriate mechanical properties. Also, the results of biological properties such as cytotoxicity, ALP activity, and ARS staining improved with Mg ion. Consequently, the optimal condition is 3 mol% of Mg ion-doped calcium silicate (3%Mg-CSC).

Enhanced mechanical and biological performances of CaO-MgO-SiO2 glass-ceramics via the modulation of glass and ceramic phases

This work reports a new CaO-MgO-SiO₂ (CMS) bioactive glass-ceramic, using ZrO₂ as a nucleus to modulate the ratios of glass and ceramic phases as a function of sintering temperature. Mg-rich bioactive CMS glass-ceramics exhibit advantages regarding mechanical strength (flexural strength ~190 MPa and compressive strength ~555 MPa), in-vitro and in-vivo biocompatibilities, and bone ingrowth. The high mechanical strengths could be attributed to the CaMgSi₂O₆ glass-ceramic and lower porosity. X-ray absorption spectra indicate an increased SiO covalent bond via the development of CaMgSi₂O₆ glass-ceramics. From the in-vitro cytotoxicity and BMSC differentiation assays, the CMS samples sintered above 800 °C exhibited better cell attachment and differentiation, possibly due to structural stability, appropriate pore, and ion release to boost osteogenesis. Compared to hydroxyapatite (HA) ceramics, the CMS glass-ceramics display higher mechanical strengths, biocompatibility, and osteoconductivity. An in-vivo experiment demonstrated a fine bone-ingrowth profile around the CMS implant. This study may further the application of CMS glass-ceramics in bone implants.

Simple and Acid-Free Hydrothermal Synthesis of Bioactive Glass 58SiO2-33CaO-9P2O5 (wt%)

The paper focuses on the acid-free hydrothermal process for the synthesis of bioactive glass. The new method avoids the use of harmful acid catalysts, which are usually used in the sol-gel process. On the other hand, the processing time was reduced compared with the sol-gel method. A well-known ternary bioactive glass 58SiO2-33CaO-9P2O5 (wt%), which has been widely synthesized through the sol-gel method, was selected to apply to this new process. Thermal behavior, textural property, phase composition, morphology, and ionic exchange were investigated by thermal analysis, N2 adsorption/desorption, XRD, FTIR, SEM, and inductively coupled plasma optical emission spectrometry (ICP-OES) analysis. The bioactivity and biocompatibility of synthetic bioactive glass were evaluated by in vitro experiments with a simulated body fluid (SBF) solution and cell culture medium. The obtained results confirmed that the acid-free hydrothermal process is one of the ideal methods for preparing ternary bioactive glass.

Li-doped bioglass® 45S5 for potential treatment of prevalent oral diseases

OBJECTIVES

Despite the excellent properties of both pure bioglasses (BG) and BG doped with therapeutic ions (such as Li) in hard tissue applications, there is not enough information about their role in the remineralization and bacterial-growth in oral diseases. The aim of this contribution is to evaluate the effect of both pure BG and BG doped with 5-wt% of Li (BGLi) on both the remineralization of in vitro demineralized human-teeth and the antimicrobial behavior against strains from caries and periodontitis.

METHODS

Bioglass® 45S5 (BG) and BGLi were synthesized by the sol-gel method. The remineralization tests were carried out using in vitro demineralized enamel teeth and evaluated by Electron Microscopy (SEM) and Vickers micro-hardness (HV). The antimicrobial behavior of the particles was evaluated against S. mutans, A. actinomycetemcomitans, and P. gingivalis, representing pathogens from caries and periodontitis.

RESULTS

Enamel lesion was partially remineralized when both bioglasses (BG and BGLi) were applied on its surface with micro-hardness recoveries around 45 %. They further inhibited the growth of S. mutans and P. gingivalis, at 50 and 200 mg/mL, respectively. BGLi presented a higher toxicity against A. actinomycetemcomitans than BG, with inhibition concentrations of 20 mg/mL and 100 mg/mL, respectively.

CONCLUSIONS

Bioglasses could be used in the treatment of two of the most prevalent oral diseases: caries and periodontitis, promoting the remineralization of the teeth and killing the main pathogens. The presence of Li did not affect the bioactivity of the bioglass and improved the antibacterial effect over A. actinomycetemcomitans strain.

Multiscale porosity in mesoporous bioglass 3D-printed scaffolds for bone regeneration

In order to increase the bone forming ability of MBG-PCL composite scaffold, microporosity was created in the struts of 3D-printed MBG-PCL scaffolds for the manufacturing of a construct with a multiscale porosity consisting of meso- micro- and macropores. 3D-printing imparted macroporosity while the microporosity was created by porogen removal from the struts, and the MBG particles were responsible for the mesoporosity. The scaffolds were 3D-printed using a mixture of PCL, MBG and phosphate buffered saline (PBS) particles, subsequently leached out. Microporous-PCL (pPCL) as a negative control, microporous MBG-PCL (pMBG-PCL) and non-microporous-MBG-PCL (MBG-PCL) were investigated. Scanning electron microscopy, mercury intrusion porosimetry and micro-computed tomography demonstrated that the PBS removal resulted in the formation of micropores inside the struts with porosity of around 30% for both pPCL and pMBG-PCL, with both constructs displaying an overall porosity of 8090%. In contrast, the MBG-PCL group had a microporosity of 6% and an overall porosity of 70%. Early mineralisation was found in the pMBG-PCL post-leaching out and this resulted in the formation a more homogeneous calcium phosphate layer when using a biomimetic mineralisation assay. Mechanical properties ranged from 5 to 25 MPa for microporous and non-microporous specimens, hence microporosity was the determining factor affecting compressive properties. MC3T3-E1 metabolic activity was increased in the pMBG-PCL along with an increased production of RUNX2. Therefore, the microporosity within a 3D-printed bioceramic composite construct may result in additional physical and biological benefits.

Role of magnesium and aluminum substitution on the structural properties and bioactivity of bioglasses synthesized from biogenic silica

The objective of this study was to investigate the effect of magnesium (1 wt%) and aluminum (1 wt%) incorporation on the in vitro bioactivity and biodegradation behavior of 45S5 bioactive glasses synthesized from rice husk biogenic silica. The performance of biogenic silica-based samples was compared well with commercial silica-based counterparts. The in vitro biodegradation behavior of bioactive glasses was evaluated by the weight loss of samples and pH variation in the Tris buffer solution. Based on composition, bioglasses possessed different properties before and after simulated body fluid (SBF) immersion. The incorporation of magnesium (Mg) and aluminum (Al) enhanced the Vickers hardness of bioglasses. All the bioglasses showed the hydroxyapatite layer formation after SBF treatment as confirmed by the dissolution, FTIR, SEM and XRD analysis, however it was more prominent in the rice husk silica-based 45S5 bioglass. The biogenic silica seems to be a promising starting material for bioglass systems to be used in bone tissue engineering applications.

Superior biocompatibility and comparable osteoinductive properties: Sodium-reduced fluoride-containing bioactive glass belonging to the CaO-MgO-SiO2 system as a promising alternative to 45S5 bioactive glass

Bioactive glasses (BGs) are promising bone substitute materials. However, under certain circumstances BGs such as the well-known 45S5 Bioglass® (composition in wt%: 45.0 SiO₂, 24.5 Na₂O, 24.5 CaO, 6.0 P₂O₅) act cytotoxic due to a strong increase in pH caused by a burst release of sodium ions. A potential alternative is a sodium-reduced fluoride-containing BG belonging to the CaO–MgO–SiO₂ system, namely BG1d-BG (composition in wt%: 46.1 SiO₂, 28.7 CaO, 8.8 MgO, 6.2 P₂O₅, 5.7 CaF₂, 4.5 Na₂O), that has already been evaluated in-vitro, in-vivo and in preliminary clinical trials. Before further application, however, BG1d-BG should be compared to the benchmark amongst BGs, the 45S5 Bioglass® composition, to classify its effect on cell viability, proliferation and osteogenic differentiation of human mesenchymal stem cells (MSCs). Therefore, in this study, the biocompatibility and osteogenic potential of both BGs were investigated in an indirect and direct culture setting to assess the effect of the ionic dissolution products and the BGs’ physical presence on the cells. The results indicated an advantage of BG1d-BG over 45S5 Bioglass® regarding cell viability and proliferation. Both BGs induced an earlier onset of osteogenic differentiation and accelerated the expression of late osteoblast marker genes compared to the control group. In conclusion, BG1d-BG is an attractive candidate for further experimental investigation. The basic mechanisms behind the different impact on cell behavior should be assessed in further detail, e.g. by further alteration of the BG compositions.

•

45S5 Bioglass® is considered to be the benchmark amongst bioactive glasses (BGs).

•

Sodium-reduced fluoride-containing BG1d BG was compared to 45S5-Bioglass®.

•

Both BGs induced osteogenic differentiation of human MSCs.

•

BG1d had an advantageous impact on cell viability and proliferation.

•

BG1d-BG is an attractive candidate for further experimental investigation.

Recent advances and future perspectives of sol–gel derived porous bioactive glasses: a review

Sol–gel derived bioactive glasses have been extensively explored as a promising and highly porous scaffold materials for bone tissue regeneration applications owing to their exceptional osteoconductivity, osteostimulation and degradation rates.

Osteogenic potential of sol-gel bioactive glasses containing manganese

Bioactive glasses (BGs) are widely used for bone regeneration, and allow the incorporation of different ions with therapeutic properties into the glass network. Amongst the different ions with therapeutic benefits, manganese (Mn) has been shown to influence bone metabolism and activate human osteoblasts integrins, improving cell adhesion, proliferation and spreading. Mn has also been incorporated into bioceramics as a therapeutic ion for improved osteogenesis. Here, up to 4.4 mol% MnO was substituted for CaO in the 58S composition (60 mol% SiO₂, 36 mol% CaO, 4 mol% P₂O₅) and its effects on the glass properties and capability to influence the osteogenic differentiation were evaluated. Mn-containing BGs with amorphous structure, high specific surface area and nanoporosity were obtained. The presence of Mn²⁺ species was confirmed by X-ray photoelectron spectroscopy (XPS). Mn-containing BGs presented no cytotoxic effect on human mesenchymal stem cells (hMSCs) and enabled sustained ion release in culture medium. hMSCs osteogenic differentiation stimulation and influence on the mineralisation process was also confirmed through the alkaline phosphatase (ALP) activity, and expression of osteogenic differentiation markers, such as collagen type I, osteopontin and osteocalcin, which presented higher expression in the presence of Mn-containing samples compared to control. Results show that the release of manganese ions from bioactive glass provoked human mesenchymal stem cell (hMSC) differentiation down a bone pathway, whereas hMSCs exposed to the Mn-free glass did not differentiate. Mn incorporation offers great promise for obtaining glasses with superior properties for bone tissue regeneration.

External Field Assisted Freeze Casting

Freeze casting under external fields (magnetic, electric, or acoustic) produces porous materials having local, regional, and global microstructural order in specific directions. In freeze casting, porosity is typically formed by the directional solidification of a liquid colloidal suspension. Adding external fields to the process allows for structured nucleation of ice and manipulation of particles during solidification. External control over the distribution of particles is governed by a competition of forces between constitutional supercooling and electromagnetism or acoustic radiation. Here, we review studies that apply external fields to create porous ceramics with different microstructural patterns, gradients, and anisotropic alignments. The resulting materials possess distinct gradient, core–shell, ring, helical, or long-range alignment and enhanced anisotropic mechanical properties.

In vitro drug release behavior of Ce-doped nano-bioactive glass carriers under oxidative stress

Ce-containing bioactive glasses are known to decrease reactive oxygen activities inside the body. That is because of their excellent catalytic activities which come from the fast interchange of Ce³⁺/Ce⁴⁺ oxidation states. This research was mainly aimed at preparing new Ce-doped nano-bioactive glasses based on 60SiO₂-(10-x)B₂O₃-25CaO-5P₂O₅-xCeO₂, in mole% (x = 0 and 5 mol%) as multifunctional bone fillings. Moreover, the glasses were used as a delivery system for ciprofloxacin to intensely solve the bone infection complications. Nevertheless, there were no previous works studied of the nature immersing solution effect on the drug release behavior from Ce-doped nano-bioactive glass carriers. Therefore, phosphate-free and phosphate-containing buffer solutions with/without superoxide species (H₂O₂) were used to investigate the efficacy of this drug delivery system in different environment. The results showed that Ce addition enhanced the formation of apatite layer and cell viability. Moreover, the percentage of released drug was apparently affected by the glass composition and nature of soaking fluid, specifically, in the media containing superoxide species (H₂O₂). In conclusion, the prepared Ce-doped glass nanoparticles illustrated multifunctional bone filling material, but when it intended to be utilized as a drug delivery system, the nature of surrounding medium have to be taken into consideration.

Mesoporous bioactive glass nanoparticles doped with magnesium: drug delivery and acellular in vitro bioactivity

The effects of the magnesium doping of binary glass (Si–Ca) on particle texture, on the biomineralization process in simulated body fluid (SBF) as well as on drug loading and release were examined. For this purpose, magnesium-doped binary bioglass nanoparticles (85SiO₂–(15 − x)CaO–xMgO, with x = 1, 3, 5 and 10 mol%) were prepared by a base catalysed sol–gel method. N₂ adsorption isotherm analysis showed an enhancement in specific surface area as the Mg molar fraction increased. In addition, the FTIR spectra of the samples after soaking in SBF for various periods of time confirmed the presence of new chemical bonds related to the apatite phase, as was also confirmed by SEM observations. XRD patterns of the samples after soaking revealed that the crystallization to form a more stable apatite-like phase was hindered with increasing magnesium content in the glass composition. Furthermore, it was proved that the kinetics of drug release improved with increasing magnesium content. The porosity and the specific surface area were found to be responsible for this improvement.

The effects of the magnesium doping of binary glass (Si–Ca) on particle texture, on the biomineralization process in simulated body fluid (SBF) as well as on drug loading and release were examined.

Bioactive Glasses and Glass-Ceramics for Healthcare Applications in Bone Regeneration and Tissue Engineering

The discovery of bioactive glasses (BGs) in the late 1960s by Larry Hench et al. was driven by the need for implant materials with an ability to bond to living tissues, which were intended to replace inert metal and plastic implants that were not well tolerated by the body. Among a number of tested compositions, the one that later became designated by the well-known trademark of 45S5 Bioglass® excelled in its ability to bond to bone and soft tissues. Bonding to living tissues was mediated through the formation of an interfacial bone-like hydroxyapatite layer when the bioglass was put in contact with biological fluids in vivo. This feature represented a remarkable milestone, and has inspired many other investigations aiming at further exploring the in vitro and in vivo performances of this and other related BG compositions. This paradigmatic example of a target-oriented research is certainly one of the most valuable contributions that one can learn from Larry Hench. Such a goal-oriented approach needs to be continuously stimulated, aiming at finding out better performing materials to overcome the limitations of the existing ones, including the 45S5 Bioglass®. Its well-known that its main limitations include: (i) the high pH environment that is created by its high sodium content could turn it cytotoxic; (ii) and the poor sintering ability makes the fabrication of porous three-dimensional (3D) scaffolds difficult. All of these relevant features strongly depend on a number of interrelated factors that need to be well compromised. The selected chemical composition strongly determines the glass structure, the biocompatibility, the degradation rate, and the ease of processing (scaffolds fabrication and sintering). This manuscript presents a first general appraisal of the scientific output in the interrelated areas of bioactive glasses and glass-ceramics, scaffolds, implant coatings, and tissue engineering. Then, it gives an overview of the critical issues that need to be considered when developing bioactive glasses for healthcare applications. The aim is to provide knowledge-based tools towards guiding young researchers in the design of new bioactive glass compositions, taking into account the desired functional properties.

Synthesis of ternary bioactive glass derived aerogel and xerogel: study of their structure and bioactivity

In this work ternary bioactive glasses with the molar composition 63 % SiO2, 28 % CaO, and 9 % P2O5 have been prepared via sol-gel processing route leading to xerogel or aerogel glasses, depending on the drying conditions. Two types of drying methods were used: atmospheric pressure drying (evaporative), to produce xerogels, and supercritical fluids drying, to obtain aerogels. Both dried gels were subjected to heat-treatment at three different temperatures: 400, 600 and 800 ºC in order to the removal of synthesis byproducts and structural modifications. The resulting materials were characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and differential thermal analysis (DTA), and by in vitro bioactivity tests in simulated body fluid. The influence of the drying and the sintering temperature of their structure, morphology, and bioactivity of the final products were evaluated. The results show a good bioactivity of xerogel and aerogel bioactive glass powders with the formation of an apatite layer after one day of immersion in SBF solution for aerogel bioactive glass powders and a particle size less than 10 nm. An apatite layer formed after 3 days in the case of xerogel bioactive glass powders and a particle size around 100 nm.

3D-printed scaffolds with bioactive elements-induced photothermal effect for bone tumor therapy

For treatment of bone tumor and regeneration of bone defects, the biomaterials should possess the ability to kill tumor cells and regenerate bone defect simultaneously. To date, there are a few biomaterials possessing such dual functions, the disadvantages, however, such as long-term toxicity and degradation, restrict their application. Although bioactive elements have been incorporated into biomaterials to improve their osteogenic activity, there is no report about elements-induced functional scaffolds for photothermal tumor therapy. Herein, the elements (Cu, Fe, Mn, Co)-doped bioactive glass-ceramic (BGC) scaffolds with photothermal effect and osteogenic differentiation ability were prepared via 3D-printing method. Moreover, the photothermal anti-tumor effect and osteogenic activity of these scaffolds were systematically investigated. The prepared elements-doped scaffolds possessed excellent photothermal performance, which displayed a trend, 5Cu-BGC > 5Fe-BGC > 5Mn-BGC > 5Co-BGC, in this study. The final temperature of elements-doped scaffolds can be well controlled by altering the doping element categories, contents and laser power density. Additionally, the hyperthermia induced by 5Cu-BGC, 5Fe-BGC and 5Mn-BGC effectively killed tumor cells in vitro and inhibited tumor growth in vivo. More importantly, 5Fe-BGC and 5Mn-BGC scaffolds could promote rabbit bone mesenchymal stem cells (rBMSCs) adhesion, and the ionic products released from elements-doped scaffolds significantly stimulated the osteogenic differentiation of bone-forming cells. These results suggested that 5Fe-BGC and 5Mn-BGC scaffolds possessed promising potential for photothermal treatment of bone tumor and at the same time for stimulating bone regeneration, representing a smart strategy for the treatment of bone tumors by combining dual functional bioactive ions with tissue engineering scaffolds.

STATEMENT OF SIGNIFICANCE

The major innovation of this study is that we fabricated the elements (Cu, Fe, Mn, Co)-doped bioactive scaffolds via 3D printing technique and found that they possess distinct photothermal performance and osteogenic differentiation ability. To the best of our knowledge, there is no report about elements-doped scaffolds for photothermal therapy of bone tumor. This is an important research advance by combining the photothermal effect and osteogenic differentiation activity of bioactive elements in the scaffold system for potential bone tumor therapy and bone reconstruction. We optimized the elements-doped scaffolds and found the photothermal effect of elements-doped scaffolds (5Cu-BGC, 5Fe-BGC, 5Mn-BGC) could effectively kill tumor cells in vivo. The photothermal performance of elements-doped scaffolds follows a trend: 5Cu-BGC > 5Fe-BGC > 5Mn-BGC > 5Co-BGC > BGC. Compared to traditional nano-sized photothermal agents, bioactive elements-induced functional scaffolds have better biosecurity and bioactivity. Furthermore, 5Fe-BGC and 5Mn-BGC scaffolds displayed excellent bone-forming activity by stimulating the osteogenic differentiation of bone-forming cells. The major significance of the study is that the elements-doped bioactive glass-ceramics (5Fe-BGC, 5Mn-BGC) have great potential to be used as bifunctional scaffolds for photothermal tumor therapy and bone regeneration, representing a smart strategy for the treatment of bone tumors by combining dual functional bioactive ions with tissue engineering scaffolds.

Effect of bioactive glass nanoparticles on biological properties of PLGA/collagen scaffold

Bioactive glasses have shown some interesting biological properties such as biocompatibility, biodegradation, and angiogenesis in skin tissue engineering. In the current research, the effects of MgO- or CoO-doped 64S bioactive glass with a composition of 64 SiO2-26 CaO-5 P2O5-5 MgO or CoO (mol%) were studied in relation with biological properties of electrospun [poly(lactic-co-glycolic acid) (PLGA)/collagen]. PLGA/collagen samples were rinsed in suspension of bioactive glass nanoparticles in distilled water with a concentration of 0.1 w/v and then freeze dried. Cell adhesion, viability, angiogenesis, and ionic release were performed and tested in culture medium containing fibroblast cells. Attachment and viability of fibroblast cells were increased significantly in bioglass-coated samples, while shrinkage in PLGA/collagen scaffold was reduced by the addition of bioactive glass. Vascular endothelial growth factor secretion in coated scaffold was dropped compared to the uncoated samples. This could be attributed to the fast degradation of glass nanoparticles, according to the inductively coupled plasma-atomic emission spectroscopy results.

A facile sol-gel synthesis of low-fusing titanium opaque porcelain using borate-silicate system and its bioactivity

The titanium opaque porcelain was synthesized through sol-gel using borate-silicate system. The porcelain was characterized by DSC-TG, X-ray diffraction, N₂ adsorption-desorption isotherms and scanning electron microscope tests. The results of DSC showed that the nitrates could be decomposed completely when the bioglass xerogel precursor was heat-treated at 760 ℃. The XRD results showed that the Na₂Ca₃Si₆O₁₆ was the major phase of the opaque porcelain. The synthesized opaque porcelain powders had an average particle size of about 5-25 µm with nanopores of around 50-70 nm on the surface. The BET average surface area of the porcelain was 12.67 m²/g, while the average pore diameters for adsorption and desorption were 9.73 and 10.16 nm, respectively. The flexure strength significantly increased from 47.4 MPa to 116.2 MPa with the sintering temperature increasing from 575 ℃ to 600 ℃. The XRD, FTIR and EDS results proved that hydroxyapatite had formed on the porcelain surface after incubation in simulated body fluid.

Synthesis, Characterization, and in Vitro Biological Evaluation of Copper-Containing Magnetic Bioactive Glasses for Hyperthermia in Bone Defect Treatment

Hyperthermia treatment induced by magnetic mesoporous glasses has been applied as a potential therapeutic approach for bone defects due to malignant tumors. The objective of this study was to synthesize and characterize the structural and biological properties of magnetic bioactive glasses (BGs) for producing multifunctional materials. The effect of the addition of copper (Cu) to the bioactive glass composition was also evaluated. Fe BG and FeCu BG as magnetic mesoporous BGs, and Cu BG as mesoporous BG were synthesized and dried by template sol-gel method. Then the synthesized bioglasses were characterized and analyzed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive electron disperse spectroscopy (EDS), Brunauer-Emmett-Teller (BET), and vibrating sample magnetometer (VSM). In addition, the antibacterial behavior, cytotoxicity assay (MTT test), proliferation assay of HUVEC cell assay, and bioactivity (ALP activity test) of the synthesized BGs were evaluated. The characterization results exhibited that the synthesized powders formed mesoporous glasses with nanoparticle morphology, good surface area, and magnetic properties. The synthesized BGs also demonstrated suitable biological behavior. The magnetic saturation of bioactive glasses was increased by the addition of copper oxide. A two-phase structure was observed for the magnetic glasses compared to the copper-containing glasses, thus making them suitable for drug delivery systems. The antibacterial behavior was found to be better for the Cu BG and Fe BG compared to the FeCu BG. However, the least amount of cytotoxicity was observed for the Fe BG and FeCu BG, compared to the Cu BG. In addition, the Fe-containing BGs compared with the control group showed a lack of HUVEC cell proliferation and angiogenesis motivation. From the ALP assay, higher bioactivity for the magnetic bioglasses in the presence of mesenchymal cells was found. From the results of this in vitro study, the Cu-containing magnetic bioglass (FeCu BG) could be considered as a new generation of magnetic glasses for inducing hyperthermia in treatment of bone defects due to malignant tumors. However, further in vitro and in vivo studies are required to confirm their applications in healing of bone defects and tissue engineering.

The facile synthesis and bioactivity of a 3D nanofibrous bioglass scaffold using an amino-modified bacterial cellulose template

Porous bioglass (BG) scaffolds are of great importance in tissue engineering because of their excellent osteogenic properties for bone regeneration. Herein, we reported for the first time the use of amino-modified bacterial cellulose (NBC) as a template to prepare a three-dimensional (3D) nanofibrous BG scaffold by a facile modified sol–gel approach under ultrasonic treatment. The results suggested that the amino groups on the BC template could effectively promote the absorption of the deposited CaO and SiO₂ precursors, and the as-obtained BG scaffold showed a 3D interconnected porous network structure consisting of nanofibers with a diameter of about 20 nm. Furthermore, the as-obtained BG scaffold showed very good bioactivity after being immersed in SBF for 7 days. This research provides a facile and efficient way to prepare a nanofibrous BG scaffold with 3D porous structure, which can be used as a promising candidate for biomedical applications.

A nanofibrous BG scaffold with a high quality 3D porous interconnected structure has been prepared via a facile modified sol–gel approach using amino-modified bacterial cellulose as the template.

Cu-releasing bioactive glass/polycaprolactone coating on Mg with antibacterial and anticorrosive properties for bone tissue engineering

Bioactive glass nanoparticles containing copper (Cu-BGNs) were introduced into polycaprolactone (PCL) coating systems to improve the bioactivity, antibacterial properties, and corrosion resistance of vulnerable magnesium matrices under physiological conditions. The influence of different amounts of Cu-BGNs in PCL coatings was thoroughly investigated in determining the wettability, electrochemical properties, and antibacterial effects against Staphylococcus carnosus and Escherichia coli, as well as their cyto-compatibility. Cu-BGNs were observed randomly scattered in PCL coatings. Increasing the concentration of Cu-BGNs resulted in a slight decrease of the water contact angle, and a reduction in anticorrosion properties of the Cu-BGN composite coatings. Yet higher Cu-BGN content in coatings led to more calcium phosphate formation on the surface after 7 days of immersion in Dulbecco's modified Eagle's medium, which was confirmed by Fourier-transform infrared spectroscopy and x-ray photoelectron spectroscopy. The growth of S. carnosus and E. coli was inhibited by Cu²⁺ ions released from the Cu-BGN coatings. In addition, both direct and indirect cyto-compatibility experiments showed that the viability and proliferation of MG-63 cells on Cu-BGN coatings were highly increased compared to pure magnesium; however, an additional increase of Cu-BGN concentration showed a slight decrease of cell proliferation and cell activity. In summary, Cu-BGN/PCL composite coatings impart magnesium-based biomaterials with antibacterial and anticorrosive properties for clinical applications.

Preparation of orthophosphate glasses in the MgO-CaO-SiO2-Nb2O5-P2O5 system

BACKGROUND

Niobia/magnesia-containing orthophosphate invert glasses were successfully prepared in our earlier work. Orthophosphate groups in the glasses were cross-linked by tetrahedral niobia (NbO4) and magnesia.

OBJECTIVE

The aim of this work is to prepare calcium orthophosphate invert glasses containing magnesia and niobia, incorporating silica, and to evaluate their structures and releasing behaviors.

METHOD

The glasses were prepared by melt-quenching, and their structures and ion-releasing behaviors were evaluated.

RESULTS

31P solid-state nuclear magnetic resonance (NMR) and Raman spectroscopies showed the glasses consist of orthophosphate (PO4), orthosilicate (SiO4), and NbO4 tetrahedra. NbO4 and MgO in the glasses act as network formers. By incorporating SiO2 into the glasses, the chemical durability of the glasses was slightly improved. The glasses reheated at 800°C formed the orthophosphate crystalline phases, such as β-Ca3(PO4)2, Mg3(PO4)2 and Mg3Ca3(PO4)4 in the glasses. The chemical durability of the crystallized glasses was slightly improved.

CONCLUSIONS

Orthosilicate groups and NbO4 in the glasses coordinated with each other to form Si-O-Nb bonds. The chemical durability of the glasses was slightly improved by addition of SiO2, since the field strength of Si is larger than that of Ca or Mg.

Role of magnesium oxide and strontium oxide as modifiers in silicate-based bioactive glasses: Effects on thermal behaviour, mechanical properties and in-vitro bioactivity

The composition of a CaO-rich silicate bioglass (BG_Ca-Mix, in mol%: 2.3 Na₂O; 2.3 K₂O; 45.6 CaO; 2.6 P₂O₅; 47.2 SiO₂) was modified by replacing a fixed 10mol% of CaO with MgO or SrO or fifty-fifty MgO-SrO. The thermal behaviour of the modified glasses was accurately evaluated via differential thermal analysis (DTA), heating microscopy and direct sintering tests. The presence of MgO and/or SrO didn't interfere with the thermal stability of the parent glass, since all the new glasses remained completely amorphous after sintering (treatment performed at 753°C for the glass with MgO; at 750°C with SrO; at 759°C with MgO and SrO). The sintered samples achieved good mechanical properties, with a Young's modulus ranging between 57.9±6.7 for the MgO-SrO modified composition and 112.6±8.0GPa for the MgO-modified one. If immersed in a simulated body fluid (SBF), the modified glasses after sintering retained the strong apatite forming ability of the parent glass, in spite of the presence of MgO and/or SrO. Moreover, the sintered glasses, tested with MLO-Y4 osteocytes by means of a multi-parametrical approach, showed a good bioactivity in vitro, since neither the glasses nor their extracts caused any negative effect on cell viability or any inhibition on cell growth. The best results were achieved by the MgO-modified glasses, both BGMIX_Mg and BGMIX_MgSr, which were able to exert a strong stimulating effect on the cell growth, thus confirming the beneficial effect of MgO on the glass bioactivity.

Development of Magnesium and Siloxane-Containing Vaterite and Its Composite Materials for Bone Regeneration

Development of novel biomaterials with Mg(2+), Ca(2+), and silicate ions releasability for bone regeneration is now in progress. Several inorganic ions have been reported to stimulate bone-forming cells. We featured Ca(2+), silicate, and especially, Mg(2+) ions as growth factors for osteoblasts. Various biomaterials, such as ceramic powders and organic-inorganic composites, that release the ions, have been developed and investigated for their cytocompatibilities in our previous work. Through the investigation, providing the three ions was found to be effective to activate osteogenic cells. Magnesium and siloxane--containing vaterite was prepared by a carbonation process as an inorganic particle that can has the ability to simultaneously release Ca(2+), silicate, and Mg(2+) ions to biodegradable polymers. Poly (l-lactic acid) (PLLA)- and bioactive PLLA-based composites containing vaterite coatings were discussed regarding their degradability and cytocompatibility using a metallic Mg substrate as Mg(2+) ion source. PLLA/SiV composite film, which has a releasability of silicate ions besides Ca(2+) ion, was coated on a pure Mg substrate to be compared with the PLLA/V coating. The degradability and releasability of inorganic ions were morphologically and quantitatively monitored in a cell culture medium. The bonding strength between the coatings and Mg substrates was one of the key factors to control Mg(2+) ion release from the substrates. The cell culture tests were conducted using mouse osteoblast-like cells (MC3T3-E1 cells); cellular morphology, proliferation, and differentiation on the materials were evaluated. The PLLA/V and PLLA/SiV coatings on Mg substrates were found to enhance the proliferation, especially the PLLA/SiV coating possessed a higher ability to induce the osteogenic differentiation of the cells.

Dissolution behavior and cell compatibility of alkali-free MgO-CaO-SrO-TiO2-P2O5 glasses for biomedical applications

Owing to their controlled solubility, phosphate invert glasses are of interest for use as temporary implant materials or tissue engineering scaffolds for controlled ion release.MgO-CaO-SrO-TiO2-P2O5 invert glasses were prepared and their dissolution behavior and cell response were examined.MgO addition to the phosphate invert glass system improved glass formation, owing to the relatively large field strength of Mg2+ ions. In osteoblastlike MC3T3-E1 cell culture tests, cell numbers on the invert glasses were significantly larger compared with the control, possibly caused by the release of Mg2+ ions promoting enhanced cell adhesion and proliferation. Alkaline phosphatase (ALP) activity varied with glass composition, with higher strontium for calcium substitution (33 to 100%) showing highest ALP activity. This effect may be caused by the release of strontium ions from the glasses.