Bioactive Glass Composites Research Articles

Surface modification of silicate, borosilicate, and phosphate bioactive glasses to improve/control protein adsorption: PART II

Bioactive glasses (BGs) are characterized by high biocompatibility and bioactivity and are particularly promising for bone tissue regeneration. Once implanted, the BGs interact with the environment and adsorb chemical moieties and biomolecules. Proteins in body fluids are critical for the success of implants, because the adsorption of specific proteins can either promote or inhibit the adhesion of surrounding tissue or other factors such as bacteria. Controlling protein adsorption by tailoring the surface properties of implanted biomaterials is fundamental. This can determine the fate of the implant. In the current study, four BG compositions (two silicates, one borosilicate, and one phosphate glass) and three model proteins (fibronectin, chimeric avidin, and streptavidin) were considered. Each BG was surface pretreated, and the adsorption of fluorescently labeled fibronectin, chimeric avidin, or streptavidin was monitored. Untreated surfaces were used as controls. The amount and spatial distribution of each protein were estimated by confocal microscopy in fluorescence modality, followed by protein clustering analysis. Although streptavidin was not adsorbed efficiently on any of the considered substrates, BGs were successfully coated with fibronectin and chimeric avidin. Both proteins showed different affinities and surface distributions as functions of the implemented pretreatment on each substrate.

A better roadmap for designing novel bioactive glasses: effective approaches for the development of innovative revolutionary bioglasses for future biomedical applications.

The introduction of bioactive glasses (BGs) precipitated a paradigm shift in the medical industry and opened the path for the development of contemporary regenerative medicine driven by biomaterials. This composition can bond to live bone and can induce osteogenesis by the release of physiologically active ions. 45S5 BG products have been transplanted effectively into millions of patients around the world, primarily to repair bone and dental defects. Over the years, many other BG compositions have been introduced as innovative biomaterials for repairing soft tissue and delivering drugs. When research first started, many of the accomplishments that have been made today were unimaginable. It appears that the true capacity of BGs has not yet been realized. Because of this, research involving BGs is extremely fascinating. However, to be successful, it requires interdisciplinary cooperation between physicians, glass chemists, and bioengineers. The present paper gives a picture of the existing clinical uses of BGs and illustrates key difficulties deserving to be faced in the future. The challenges range from the potential for BGs to be used in a wide variety of applications. We have high hopes that this paper will be of use to both novice researchers, who are just beginning their journey into the world of BGs, as well as seasoned scientists, in that it will promote conversation regarding potential additional investigation and lead to the discovery of innovative medical applications for BGs.

In vitro bioactivity and biocompatibility of magnesium implants coated with poly(methyl methacrylate) - bioactive glass composite

Magnesium (Mg) and its alloys have proved promising as biodegradable candidates for the repair of bone tissue. Despite the encouraging bio-related properties of Mg, its high corrosion rate in contact with body fluids still presents a major challenge. An efficient approach to address this issue is to provide a protective coating on Mg. The present research evaluates, for the first time, in vitro bioactivity and biocompatibility of a novel multifunctional composite coating based on poly(methyl methacrylate) (PMMA) biopolymer and bioactive glass (BG) particles on Mg-based implant. Electrophoretic deposition (EPD) was utilized to obtain this coating from a bi-component suspension. Coatings’ morphological analyses by scanning electron microscopy established that EPD provides a facile route for simultaneous deposition of the biopolymeric matrix and BG in the form of a dense and homogeneous coating on the surface of Mg. Chemical characterizations of the coatings performed by energy-dispersive spectroscopy and FT-IR spectroscopy confirmed the presence of both PMMA and BG components in the composite film. In vitro acellular bioactivity test in simulated body fluid (SBF) verified bone-like apatite formation on coatings due to the presence of BG particles. Additionally, in vitro cellular cytotoxicity using MTT assay demonstrated cellular viability in contact with the composite coatings. Moreover, the corrosion behavior of the pure Mg vs coated Mg samples in SBF was assessed electrochemically using linear polarization and impedance spectroscopy techniques. A significant increase in the polarization resistance from 65.89 Ω.cm 2 for uncoated Mg to 1365.1 Ω.cm 2 for Mg coated with a composite film (obtained from 45 g/L PMMA and 3.5 g/L BG suspension) was observed. This indicated a reduction of 95.17% in the corrosion rate of Mg substrate by application of a composite coating. The dramatic reduction in Mg substrate corrosion rate accompanied by in vitro bioactivity and cytocompatibility of the developed composite, reflect the high potential of the present strategy in the modification of Mg-based implants for successful bone tissue engineering applications. • Novel bioactive and corrosion-resistant composite coating on Mg biomedical implant • PMMA facilitates bioactive glass deposition via a facile electrophoretic method • Composite coatings were bioactive due to apatite formation in simulated body fluid • 95.17% reduction in corrosion rate in composite-coated Mg vs bare Mg • Coatings supported the growth of MG63 cells and were non-cytotoxic

Glass as a biomaterial: strategies for optimising bioactive glasses for clinical applications

Bioactive glasses were the first synthetic materials to bond to human body tissue, making them ideal for replacing and regenerating bone. Since their first development over half a century ago, many new bioactive glass compositions have been developed for medicine and dentistry. This paper looks at different design strategies employed over the years as well as aspects of glass structure relevant to optimising bioactive glass performance. Statistical compositional series allowed for getting an overview of various compositions and their properties. Since the improvement of structural analysis techniques, particularly solid-state NMR, we can directly relate several bioactive glass properties to the atomic structure, i.e. the spatial arrangement of atoms. Such detailed understanding of the impact of composition and structure on bioactive glass properties enables us to minimise the number of compositions in preclinical and clinical tests needed to confirm positive tissue responses.

Glycol thermal synthesis of the 45B5 bioactive borate glass: Structural, physical, and apatite mineralization in vitro

This work was performed aiming to develop a new and straightforward route for bioactive glasses obtention with minimal equipment and explore the structural, physical, and bioactivity properties of the resulting glass and its glass ceramics. Herein, the synthesis of the borate bioactive glass in the 45B5 composition (46.1 B2O3 – 26.9 CaO – 24.4 NaO – 2.6 P2O5, mol%) by the glycol thermal method was proposed; an original chemical route for bioactive glass obtention based on transesterification reaction between the precursors with a glycol. The suggested mechanism for the borate network formation was proven accurate, revealing a vitreous structure formed by ring-type metaborate structural units with a lamellar morphology upon calcination. Glass-ceramics obtained at 500 (45B5-500) and 700 °C (45B5-700) indicate the oxides were effectively incorporated into the network by crystallization of Ca–Na–B, Ca–B, and Na–B phases. The in vitro apatite mineralization assay performed on the glass and glass-ceramics revealed their great solubility and conversion rate into hydroxyapatite (HA, Ca5(PO4)3(OH)), which is taken as an indication of bioactivity. Besides HA, however, calcium carbonate species were identified at the early stages of mineralization for 45B5 and 45B5-500, suggesting the 45B5-700 glass-ceramic has a higher ability to form apatite as the majority of Ca2+ are directed to precipitate into hydroxyapatite. Overall, the 45B5 glass and glass-ceramics demonstrated their great bioactivity, having high application potential in soft tissue engineering on wound healing materials and devices, as incorporation in hydrogels and nanofibers. Furthermore, the glycol thermal method generated new perspectives for the synthesis of a broad range of bioactive glasses compositions and their application in tissue engineering.

A novel composition of bioactive glass with potent haemostatic action and antibacterial competence

Haemorrhagic bleeding is a crucial area of concern related to military as well as civilian trauma. In recent years, bioactive glass is gaining attention in a number of healthcare applications, including haemostasis. Herewith, we report a unique composition of bioactive glass, 70 SiO2: (30-x-y) CaO: x.Al2O3: y.ZnO, where x = 10–18 mole% and y = 0–8 mole%, (Al-BAG) exhibiting haemostatic property as well as antibacterial activity. The as-prepared glass was characterized using XRD, SEM-EDX, FTIR and TG-DSC along with in-vitro degradation study and biological studies e.g., cytocompatibility, haemocompatibility, in-vitro thrombus formation, in-vitro blood absorption capacity, blood coagulation assays (PT, aPTT), in-vitro antibacterial assay against Staph. aureus as well as in-vivo acute dermal toxicity followed by histopathological analysis) and in-vivo haemostasis efficacy were undertaken. The novel bioactive glass composition exhibits promises to be an efficient haemostatic agent with antibacterial activity.

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

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

Characterizing the Properties of 70Si-30Ca Bioglass-Magnesia Composite as Hard Tissue Replacement Bio-Materials

There are many requirements for biomaterials used in the applications of bone tissue engineering, besides their biocompatibility, they should exhibit acceptable mechanical properties to mimic bone properties. Many research areas in bioactive materials for bone tissue engineering focused on producing new bioactive glass and ceramic compositions containing a trace of inorganic elements (such as Mg, Sr, Cu, Zn) to combine the mechanical properties and bioactivity. In the present study bioglass-MgO composite material has been used to produce Diopside (CaMgSi2O6) by the sintering process. The compact samples were made from a mixture powder of (7, 15)wt% MgO and binary bioglass 70Si-30Ca sintered at 1100 ᵒC for 2 hr. The XRD results confirmed the presence of diopside and wollastonite CaSiO3 in the case of using 7wt.% MgO while the structure was completely diopside at 15 Wt.% MgO. Physical properties, compressive strength, and hardness were investigated, as well as biodegradation behavior and bioactivity in human saliva were inspected. The results confirmed improving the mechanical properties along with increasing MgO as well as proved the ability to form hydroxyapatite on the surface when exposed to human saliva. These findings demonstrated the positive role of MgO in the mechanical properties of 70Si-30Ca bioactive glass besides producing diopside as a good candidate for hard tissue engineering.

Synthesis and in vitro characterization of superparamagnetic γ-Fe2O3-containing 13–93 bioactive glasses for bone cancer therapy

Osteosarcoma is one of the most common types of bone cancer, which generally starts in the long bones. In this study, superparamagnetic maghemite-containing (2, 5, 10, 20 wt%) bioactive glass powders were prepared for the treatment of osteosarcoma. For this purpose, maghemite nanoparticles were synthesized using the co-precipitation technique, and maghemite-containing bioactive glass-ceramic composites were fabricated through the sol-gel process. The structural, morphological, thermal, and magnetic properties and the in vitro bioactivity of the prepared bioactive glasses were investigated. In vitro cytotoxicity was examined using SaOS-2 and MC3T3-E1 cells. The fluorouracil (5-FU) release behavior of the studied bioactive glass powders was also monitored in phosphate-buffered saline as a function of time. Results revealed that synthesized maghemite nanoparticles as well as the maghemite-containing bioactive glass-ceramic composites have superparamagnetic properties. They have high bioactivity, with up to 5 wt% maghemite content. Prepared bioactive glass composites have no cytotoxicity against osteosarcoma and pre-osteoblast cells at low concentrations. Drug-loaded bioactive glass powder showed sustained release behavior. Overall results indicated that prepared glass composites have a high potential to be used in magnetic hyperthermia and anticancer drug release applications for the treatment of bone cancer.

Biodegradation behavior of polymethyl methacrylate−bioactive glass 45S5 composite coated magnesium in simulated body fluid

The biodegradation behavior of Mg, coated by polymethyl methacrylate as well as polymethyl methacrylate (PMMA)−bioactive glass (BG) composite was investigated. Electrophoretic deposition and dip coating techniques were adopted to prepare composite coating using a suspension of different percentages of the above two chemical materials. The deposited coatings were characterized using SEM, EDS, FTIR, and water contact angle measurements. Biodegradation behavior study of the coated Mg was performed using linear polarization, impedance spectroscopy, and immersion tests in simulated body fluid. The compact and homogeneous composite coating was developed as evidenced by electron microscopy results. The water contact angle measurement showed a 44° increase in the contact angle of the composite coated Mg compared to the uncoated one. The composite coating was covered by a bone-like hydroxyapatite layer after 336 h, indicating that the coating has an excellent in vitro bioactivity. The electrochemical testing results confirmed a significant reduction, 96.9%, in the biodegradation rate of Mg coated with the composite prepared from 45 g/L PMMA + 3.5 g/L 45S5 GB suspension compared to that of the uncoated one. Therefore, the composite coated Mg can be proposed as a promising material for biodegradable implant application.

Deposition of bioactive glass coatings based on a novel composition containing strontium and magnesium

In this work a novel bioactive glass composition was used to deposit coatings by means of plasma spraying. Different coatings were manufactured and optimized by varying the processing parameters and were studied by X-ray diffraction and scanning electron microscopy. Moreover, the bioactivity was assessed by in vitro tests in Simulated Body Fluid solution.The coatings displayed the typical microstructure of atmospheric plasma sprayed coatings, that is a coating made up by the stacking of melted splats, with different thicknesses, porosities and crystalline phases depending on the spraying parameters used. The work showed that all the coatings are denser and with less porosity than those observed for plasma sprayed coatings of the well-known 45S5 bioactive glass, with similar particle size deposited under the same spraying conditions. The in vitro tests demonstrated the bioactive aptitude of all the coatings, on whose surface an hydroxycarbonate apatite layer formed after 7 days of soaking.

New and Efficient Bioactive Glass Compositions for Controlling Endodontic Pathogens.

Endodontic treatment aims to conserve teeth through removing infected tissue, disinfecting, and filling/sealing the root canal. One of the most important treatment steps is the removal of microorganisms to avoid reinfection and consequent tooth loss. Due to increased resistance to intracanal medications, new alternative procedures are needed. Thus, an intracanal medication is suggested using three bioactive glass (BG) compositions (BG1, BG2, and BG3) produced by the sol–gel method, with different molar contents of bactericidal oxides. The BGs were morphologically and physically characterized. Their ability to inhibit the growth of two oral pathogens responsible for the failure of endodontic treatments (E. faecalis and C. albicans) was also studied. The results suggest that BG2 and BG3 can inhibit the growth of E. faecalis after 48 h of incubation, and all BG samples have a significant effect on C. albicans survival.

Can 3D-Printed Bioactive Glasses Be the Future of Bone Tissue Engineering?

According to the Global Burden of Diseases, Injuries, and Risk Factors Study, cases of bone fracture or injury have increased to 33.4% in the past two decades. Bone-related injuries affect both physical and mental health and increase the morbidity rate. Biopolymers, metals, ceramics, and various biomaterials have been used to synthesize bone implants. Among these, bioactive glasses are one of the most biomimetic materials for human bones. They provide good mechanical properties, biocompatibility, and osteointegrative properties. Owing to these properties, various composites of bioactive glasses have been FDA-approved for diverse bone-related and other applications. However, bone defects and bone injuries require customized designs and replacements. Thus, the three-dimensional (3D) printing of bioactive glass composites has the potential to provide customized bone implants. This review highlights the bottlenecks in 3D printing bioactive glass and provides an overview of different types of 3D printing methods for bioactive glass. Furthermore, this review discusses synthetic and natural bioactive glass composites. This review aims to provide information on bioactive glass biomaterials and their potential in bone tissue engineering.

Effect of local ion concentrations on the in vitro reactions of bioactive glass 45S5 particles

AbstractBioglass 45S5 is the most widely used bioactive glass composition in orthopedics to regenerate bone tissue. Although its reactions in vitro and in vivo are well established, the impact of the local environment on the dissolution behavior in the dynamic environment is not fully understood. Here, we show that the ion concentrations released from 45S5 into Tris‐buffer solution and simulated body fluid (SBF) in a cascade system of three reactors in a series significantly differed depending on the ion concentrations in the inflow solutions to each reactor. The ion concentrations and pH of the solutions were measured after each reactor for up to 7 days. Also, the reaction layers at the glass particles were analyzed. The release of Si species into Tris decreased in the consecutive reactors from 92% to 26% and 24% at 168 h. Correspondingly, the release of Si species into SBF decreased from 35% to 20% and 19%. The share of elements in the remaining glass particles markedly varied between the reactors throughout the dissolution. The results imply that gradients of local ion concentrations have an essential effect on the dissolution of 45S5. The results provide guidelines for utilizing Bioglass 45S5 in different bone and soft tissue applications.

Chemical Composition, Mechanical, and Thermal Characteristics of Bioactive Glass for Better Processing Features

Chemical Composition, Mechanical, and Thermal Characteristics of Bioactive Glass for Better Processing Features

Effect of boron oxide on mechanical and thermal properties of bioactive glass coatings for biomedical applications

AbstractBioactive glass coatings can improve the osteo integration of metallic implants with the host tissue, thereby increasing their lifespan and overall success rate. However, complex composition‐structure‐property relations in phosphosilicate‐based bioactive glasses make experimental determination of these relations and related composition design of bioactive coatings challenging. By applying molecular dynamics (MD)‐based atomistic simulations with recently developed effective potentials, this work addresses the challenge by using a material genome approach to obtain the composition and structure effects on various key properties for bioactive coating applications. A series of potential bioactive glass compositions were studied and the composition effects on the mechanical and thermal properties that are critical to these bioactive glasses as a coating to metallic implants were calculated. Particularly, by varying the level of B2O3 to SiO2 substitutions, the effect of composition on various key properties was elucidated. It was found that by using cation in a 1 to 1 ratio (BO3/2 to SiO2) instead of the commonly used substitutions (B2O3 to SiO2), the composition effect can be more clearly expressed and, hence, recommended in future composition designs. Together with careful structural analysis, the origin of property changes can be elucidated. The atomistic computer simulation‐based approach is, thus, an effective way to guide future bioactive glass designs for bioactive coatings and other applications.

Effect of sintering temperature on mechanical and bioactivity properties of bioactive glass and cordierite composite

In this study, a composite of bioactive glass (BG) and cordierite (BG-cord) was proposed to increase the strength and bioactivity of BG. Both BG and cordierite were separately synthesized with the method of glass melting, then, they were used to fabricate BG-cord with a variation of sintering temperature (600 to 1000 °C). The highest diametral tensile strength (DTS=30.54 MPa) was shown by the BG-cord with sintering temperature at 925 ºC. Bioactivity tests were conducted by soaking in Hank’s balanced salt solution (HBSS) for 7, 14, and 21 days. Apatite formation was examined by using a scanning electron microscope. The results showed that the sample showed good bioactivity with regards to the formation of apatite on the samples, confirmed by the detection of carbonate (C-O) and phosphate (P-O) absorption peaks by Fourier transform infrared spectroscopy and crystalline peaks in the X-ray diffraction pattern.

Bioactive glass selectively promotes cytotoxicity towards giant cell tumor of bone derived neoplastic stromal cells and induces MAPK signalling dependent autophagy.

Giant cell tumors of bone (GCTB) are associated with massive bone destructions and high recurrence rates. In a previous study, we observed cytotoxic effects of three different compositions of bioactive glasses (BGs) towards GCTSC but not bone marrow derived stromal cells (BMSC) indicating that BGs represent promising candidates for the development of new therapeutic approaches. In the current study we aimed to investigate the molecular mechanisms that are involved in BG induced cytotoxicity. We observed, that BG treatment was not associated with any signs of apoptosis, but rather led to a strong induction of mitogen activated protein kinases (MAPK) and, as a consequence, upregulation of several transcription factors specifically in GCTSC. Genome wide gene expression profiling further revealed a set of fifteen genes that were exclusively induced in GCTSC or induced significantly stronger in GCTSC compared to BMSC. BG treatment further induced autophagy that was significantly more pronounced in GCTSC compared to BMSC and could be inhibited by MAPK inhibitors. Together with the known osteogenic properties of BGs our findings support the suitability of BGs as therapeutic agents for the treatment of GCTB. However, these data have to be verified under in vivo conditions.

Factors governing the sinterability, In vitro dissolution, apatite formation and antibacterial properties in B2O3 incorporated S53P4 based glass powders

In this report, we have systematically evaluated the role of boron in regulating the degradation, apatite formation and antibacterial properties of bioactive glasses by substituting SiO 2 with B 2 O 3 in S53P4 based glass composition. The structural analysis of the glasses has been carried out using neutron diffraction and Raman spectroscopic techniques. The structural analysis of S53P4 base glass has revealed the presence of silicate and phosphate units in the form of Q 2 Si , Q 3 Si and isolated Q 0 P units. With the increasing replacement of SiO 2 with B 2 O 3 , Raman spectroscopy revealed the formation of non-ring metaborate units and borate rings consisting of both BO 3 and BO 4 units at the expense of Q 2 Si and Q 3 Si units. Furthermore, DSC, HSM and dilatometry results confirmed that the sinterability parameter (S c ) and fragility index (m) values of borosilicate bioactive glasses help in achieving superior sintering and thermal processing without devitrification. Additionally, in vitro SBF immersion studies revealed an accelerated release of Si 4+ and Ca 2+ ions from the borosilicate glasses. In vitro antibacterial assays against E.coli bacterial inoculum illustrate the critical role of B 2 O 3 in the bioactive glass composition.

Physical, optical, and radiation characteristics of bioactive glasses for dental prosthetics and orthopaedic implants applications

The melt-quench procedure was employed to create five different composition of bioactive glasses with TiO2 modifications. The optical and shielding characteristics the bioglasses have all undergone significant changes. X-ray diffraction studies were subjected to investigate the glasses' amorphous character. The absorption and transmission of the prepared glasses are measured to examine optical characteristics. The energy gap expands, whereas Urbach reduces. The physical constants basicity, polarizability, and electronegativity are all determined. Phy-X/PSD was employed to explore radiation shielding features. Because the addition of TiO2, sample G5 has the best radiation features. The outcomes show that adding TiO2 to bioactive glass compositions has a significant impact on their optical and radiation shielding features. As a result of the composition, a new bioglass system has been created that can be used in a variety of applications, including dental prosthetics and orthopaedic implants.