AbstractCitation analysis of a certain publication acknowledges its impact on the scientific community. This study conducted a multivariate analysis of the top 50 most cited articles published on the field of Bioactive Glass. A systemic search was performed using the “All database” section of the Web of Science to retrieve the top 50 most cited original publications. The selected articles were then manually cross-matched with Elsevier Scopus and Google Scholar Database. Parameters such as article title, authorship, institution, country of publication, year, citation count, citation density, current citation index, and journal name were retrieved from Web of Science. Different ranges of citation numbers were retrieved for these publications in which 197-913 are from Web of Science, 209-962 are from Elsevier Scopus, and 269-1225 are from Google Scholar. A total of 153 authors contributed to this marked list, where Professor L.L. Hench contributed the highest number of articles (n=21). Imperial College London published the highest number of articles (n=21). In summary, this study provides a good scientometric picture of bioactive glass related publications, which illustrate the trend of biomaterials development over the years and suggests future scopes to the scientific community.
AbstractOver the last years, three-dimensional (3D) printing has been successfully applied to produce suitable substitutes for treating bone defects. In this work, 3D printed composite scaffolds of polycaprolactone (PCL) and strontium (Sr)- and cobalt (Co)-doped multi-component melt-derived bioactive glasses (BGs) were prepared for bone tissue engineering strategies. For this purpose, 30% of as-prepared BG particles (size <38 μm) were incorporated into PCL, and then the obtained composite mix was introduced into a 3D printing machine to fabricate layer-by-layer porous structures with the size of 12 × 12 × 2 mm3.The scaffolds were fully characterized through a series of physico-chemical and biological assays. Adding the BGs to PCL led to an improvement in the compressive strength of the fabricated scaffolds and increased their hydrophilicity. Furthermore, the PCL/BG scaffolds showed apatite-forming ability (i.e., bioactivity behavior) after being immersed in simulated body fluid (SBF). The in vitro cellular examinations revealed the cytocompatibility of the scaffolds and confirmed them as suitable substrates for the adhesion and proliferation of MG-63 osteosarcoma cells. In conclusion, 3D printed composite scaffolds made of PCL and Sr- and Co-doped BGs might be potentially-beneficial bone replacements, and the achieved results motivate further research on these materials.
Abstract Porosity is known to play a pivotal role in dictating the functional properties of biomedical scaffolds, with special reference to mechanical performance. While compressive strength is relatively easy to be experimentally assessed even for brittle ceramic and glass foams, elastic properties are much more difficult to be reliably estimated. Therefore, describing and, hence, predicting the relationship between porosity and elastic properties based only on the constitutive parameters of the solid material is still a challenge. In this work, we quantitatively compare the predictive capability of a set of different models in describing, over a wide range of porosity, the elastic modulus (7 models), shear modulus (3 models) and Poisson’s ratio (7 models) of bioactive silicate glass-derived scaffolds produced by foam replication. For these types of biomedical materials, the porosity dependence of elastic and shear moduli follows a second-order power-law approximation, whereas the relationship between porosity and Poisson’s ratio is well fitted by a linear equation.
AbstractThis study investigates the role of yttrium in phosphate-based glasses in the system 45(P2O5)–25(CaO)– (30-x)(Na2O)–x(Y2O3) (0≤x≤5) prepared via melt quenching and focuses on their structural characterisation and degradation properties. The structural analyses were performed using a combination of solid-state nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). 31P NMR analysis showed that depolymerisation of the phosphate network occurred which increased with Y2O3 content as metaphosphate units (Q2) decreased with subsequent increase in pyrophosphate species (Q1). The NMR results correlated well with structural changes observed via FTIR and XPS analyses. XRD analysis of crystallised glass samples revealed the presence of calcium pyrophosphate (Ca2P2O7) and sodium metaphosphate (NaPO3) phases for all the glass formulations explored. Yttrium-containing phases were found for the formulations containing 3 and 5 mol% Y2O3. Degradation analyses performed in Phosphate buffer saline (PBS) and Milli-Q water revealed significantly reduced rates with addition of Y2O3 content. This decrease was attributed to the formation of Y-O-P bonds where the octahedral structure of yttrium (YO6) cross-linked phosphate chains, subsequently leading to an increase in chemical durability of the glasses. The ion release studies also showed good correlation with the degradation profiles.
AbstractIn this study, injectable pastes based on a clinically-tested bioactive glass and glycerol (used as organic carrier) were produced and characterized for further application in regenerative medicine. The paste preparation route, apatite-forming ability in simulated body fluid (SBF) solution, viscoelastic behavior and structural features revealed by means of scanning electron microscopy (SEM), FTIR and Raman spectroscopy were presented and discussed, also on the basis of the major experimental data obtained in previous studies. A mechanism illustrating the chemical interaction between bioactive glass and glycerol was proposed to support the bioactivity mechanism of injectable pastes. Then, the results of In vivo tests, conducted through injecting moldable paste into osseous defects made in rabbit’s femur, were reported. Animal studies revealed good osteoconductivity and bone bonding that occurred initially at the interface between the glass and the host bone, and further supported the suitability of these bioactive glass pastes in bone regenerative medicine.
AbstractMultifunctionality can be achieved for bioactive glasses by endowing them with multiple other properties along with bioactivity. One way to address this topic is by doping these glasses with therapeutic metallic ions. In this work, we put under investigation a series of bioactive glasses doped with tantalum. We aim to study the effect of tantalum, on the structure, bioactivity and antibacterial property of a ternary bioactive glass composition based on SiO2-CaO-P2O5. Fourier Transformed Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD) and Electron Scanning Microscopy (SEM) were used to assess the structural and morphological properties of these glasses and monitor their changes after in vitro acellular bioactivity test. Antibacterial activity was tested against gram positive and negative bacteria. Characterization results confirmed the presence of calcium carbonate crystallites along with the amorphous silica matrix. The assessment of bioactivity in SBF indicated that all compositions showed a fast bioactive response after only six hours of immersion period. However, analytical characterization revealed that tantalum introduced a slight latency in hydroxyapatite deposition at higher concentrations (0.8-1 %mol). Antibacterial test showed that tantalum ions had an inhibition effect on the growth of E. coli and S. aureus. This effect was more pronounced in compositions where mol% of tantalum is superior to 0.4%. These results proved that tantalum could be used, in intermediate proportions, as a promising multifunctional dopant element in bioactive glasses for bone regeneration applications.
AbstractPersistent luminescent amorphous borosilicate scaffolds were successfully prepared, for the first time, with a porosity of >70% using the burn-off technique. The persistent luminescence was obtained by adding the SrAl2O4:Eu2+,Dy3+ microparticles: i) in the glass melt or ii) in the glass crushed into powder prior to the sintering. The scaffolds prepared by adding the microparticles in the glass melt exhibits lower persistent luminescence and a slower reaction rate in simulated body fluid than the scaffolds prepared by adding the microparticles in the glass powder due to the release of strontium from the microparticles into the glass during the glass melting.
Abstract Bioactive glass was first developed in the late 1960’s as a compound that would facilitate bone re-growth. In more recent years, this technology has been used to promote wound healing through its ability to stimulate soft tissue growth, angiogenesis, reduce inflammation, and prevent infection. Chronically infected wounds, which result from biofilm formation, affect millions of patients in the Unites States each year and cost billions of dollars to treat. The present studies demonstrate exposure of pre-formed biofilms to bioactive glass, under simulated body conditions, resulted in significant reduction in bacterial load. Additionally, specific therapeutically active metal ions such as copper and zinc were added to a borate bioactive glass formulation through a process of ion doping and found to further enhance the anti-biofilm activity. Based on the present findings, the antibiofilm agents released by borate bioactive glasses may prove effective to eradicate the biofilm infections that prevent healing in patients with chronic wounds.
Abstract The present study reports the dissolution studies of a family of boron-doped bioactive glasses based on the composition ICIE16. Simulated body fluid (SBF), Tris-buffered solution and lactic acid were used as dissolution media for studies under static and dynamic conditions. The leaching of ions from the glasses under the evaluated conditions and media was compared and the bioactive behaviour of the glasses was evaluated. Influence of the incorporation of boron in the thermal properties of the glass was also analysed. Glasses exhibited faster bioactivity under dynamic dissolution configuration compared to static conditions. Moreover, the glass dissolution rate was faster in acidic conditions than in SBF or Tris solutions. It was found that at increasing boron content the dissolution of the glass is faster.
Abstract After five decades of research on bioactive glasses and glass-ceramics, these materials became of considerable interest due to their revolutionary potential for numerous health applications, including cancer treatment. One advantage of glass-ceramics compared with other materials – such as metallic alloys and polymers – is their capability of being highly bioactive and, if desired, containing magnetic phases. Hyperthermia (HT) is an alternative for treating cancer; the strategy is to increase the temperature of the tumor using an external magnetic field that increases the temperature of an implanted magnetic material, which works as an internal heat source. This local increase of temperature, ideally to ~43°C, could kill cancer cells in situ without damaging the healthy surrounding tissue. To achieve such goal, a material that presents a balance between proper magnetic properties and bioactivity is necessary for the safe applicability and successful performance of the HT treatment. Certainly, achieving this ideal balance is the main challenge. In this article we review the state-of-the-art on glass-ceramics intended for HT, and explore the current difficulties in their use for cancer treatment, starting with basic concepts and moving onto recent developments and challenges.
Even if the first paper of Prof. Larry Hench that introduced bioactive glass and its properties was published in 1971 (the seminal paper in J. Biomed. Mater. Res. [1]), the actual discovery of bioactive glass and its bone bonding properties dates back to 1969, in the laboratory of Prof. Hench at University of Florida, USA. Over the last 50 years, bioactive glasses, originally intended for applications as bone substitutingmaterials and small orthopedic implants, have expanded in their functionalities and applications, based on innovative chemical compositions and novel processing techniques, to areas such as biomedical coatings, dental care, scaffolds for tissue engineering, and as components of advanced devices for drug delivery, wound healing, soft tissue repair and potential uses in cancer treatment. The present special issue in "Biomedical Glasses" marks the 50th Anniversary of bioactive glass, including a collection of papers written by members of the bioactive glass research community, on a great variety of topics related to the development, properties and applications of bioactive glasses. The collection includes a review paper by David Greenspan, who was the main driving force behind the commercialization of Bioglass (the original bioactive glass composition) and subsequent products that evolved from it, from bone grafts to toothpaste. David summarizes the early development of bioactive glasses and highlights the legacy of Prof. Hench in the broad biomaterials field [2]. Another review paper, by the group of Edgar Zanotto, covers the emerging field of bioactive magnetic glass-ceramics for cancer treatment [3]. Application of bioactive glasses in bone cements is discussed in the papers of Wetzel et al. [4] andMokhtari et al. [5], while applications of different bioactive glasses in bone tissue engineering scaffolds are covered by the papers of Brokmann et al. [6], and Barberi et al. [7] and the field of wound healing and antibacterial effects of bioactive glasses is the subject of the paper of Jung et al. [8]. The special volume includes also several papers featuring the growing field of bioactive glasses incorporating biologically active ions, in this case: Cu [5], Mg [9], Zn [10], B [8, 11–13], F [14–16], Ag [15], Gd [17]. These studies cover fundamental investigations on the structure, crystallization behavior, thermal properties, biocompatibility, bioactivity, dissolution kinetics and biodegradability of a series of bioactive glasses of silicate, phosphate and borate composition, obtained by melting or sol-gel methods. We hope that the present volume will represent a valuable source of information for bioactive glass researchers and that it will be seen as a fitting collection to commemorate the 50th Anniversary of bioactive glass and the legacy of Prof. Larry Hench.
Abstract The biocompatibility of photosensitive glasses allows various biomedical applications; one is the field of tissue engineering and more precisely microengineered tissue-on-a-chip platforms to study the tissue microenvironment and disease modelling. Three dimensional architectures of adapted components are required for modern materials. A photosensitive lithiumalumosilicate glass FS21 was investigated regarding the interaction with a Ti:Sapphire laser systemto build three dimensional buried channels inside the glass. Femtosecond laser radiation with a wavelength of 800 nm and pulse duration of 140 fs was used to modify the glass structure. Subsurface channel geometries were achieved by a subsequent thermal treatment and were formed into capillaries using wet chemical etching of the exposed and crystallised channels. Contrary to ultraviolet (UV) exposure, spectral optical investigations showed that fs laser exposure caused various radiation induced defects in the base glass coupled with the generation of photoelectrons for the photochemical modification of silver ions. We observed an outgassing of different species coming from raw materials of the original glass batch during the glass crystallisation process. Etch rate ratios differ between 1:25 and 1:45 and are dependent on: stoichiometric deviation between surface and bulk, crystal size and distribution and exchange of the etching agent in narrow capillaries.
Abstract Bioactive glasses are important for biomedical and dental applications. The controlled release of key ions, which elicit favourable biological responses, is known to be the first key step in the bioactivity of these materials. Properties such as bioactivity and solubility can be tailored for specific applications. The addition of fluoride ions is particularly interesting for dental applications as it promotes the formation of fluoro-apatite. To date there have been mixed reports in the literature on how fluorine is structurally incorporated into bioactive glasses. To optimize the design and subsequent bioactivity of these glasses, it is important to understand the connections between the glass composition, structure and relevant macroscopic properties such as apatite formation and glass degradation in aqueous media. Using neutron diffraction, high energy X-ray diffraction, 29Si NMR, FTIR and XPS we have investigated the atomic scale structure of mixed calcium oxide / calcium fluoride silicate based bioactive glasses. No evidence of direct Si-F bonding was observed, instead fluorine was found to bond directly to calcium resulting in mixed oxygen/fluoride polyhedra. It was therefore concluded that the addition of fluorine does not depolymerise the silicate network and that the widely used network connectivity models are valid in these oxyfluoride systems.
Abstract Glass ionomer cements (GIC) are used in restorative dentistry and their properties (low heat during setting, adhesion to mineralised tissue and surgical metals) make them of great interest for bone applications.However, dental GIC are based on aluminium-containing glasses, and the resulting release of aluminium ions from the cements needs to be avoided for applications as bone cements. Replacing aluminium ions in glasses for use in glass ionomer cements is challenging, as aluminium ions play a critical role in the required glass degradation by acid attack as well as in GIC mechanical stability. Magnesium ions have been used as an alternative for aluminium in the glass component, but so far no systematic study has looked into the actual role of magnesium ions. The aim of the present study is therefore the systematic comparison of the effect of magnesium ions compared to calcium ions in GIC glasses. It is shown that by partially substituting MgO for CaO in simple SiO2-CaO-CaF2 glasses, ion release from the glass and, subsequently, GIC setting behaviour can be adjusted. Magnesium ions act as typical network modifiers here but owing to their larger field strength compared to calcium ions reduce ion release from the glasses significantly. By choosing an optimum ratio of magnesium and calcium ions in the glass, GIC setting and subsequently compressive strength can be controlled.
Abstract In 1969, fifty years ago, a young professor of ceramic engineering created a 4-component glass to be used as a bone replacement material. That material became known as “Bioglass” and more generally as a class of materials known as bioactive glass. Those first experiments conducted by Dr. Larry Hench completely shifted the paradigm of how the biomaterials and medical communities look at the interactions between inorganic materials and tissues in the body. This article will touch on just a few highlights of the development of bioactive glasses and relate those to the concepts of bioactivity and tissue bonding.
Abstract Rare Earth (RE)-containing bioactive glasses has recently gained more relevance in the field of biomaterials due to the unique optical, electronic, and chemical properties of the RE elements. In this work, the influence of gadolinium in the thermal properties of bioactive glasses based on the SiO2-Na2O-CaO-P2O5 containing different Na/Ca ratio was studied. The glasses were obtained by melting-quenching, and their properties were evaluated by differential thermal analysis, X-ray diffraction, and scanning electron microscopy. The results evidenced that Gd tends to increase the working temperature (Tc-Tg) in Ca-rich glasses, which leads to a less tendency to devitrification. On the other hand, in Na-rich glasses, Gd did not play an essential role in crystallization, and the thermal properties of Gd-containing Na-rich glasses were similar to their counterparts. In conclusion, we suggested that it is possible to control the influence of Gd in the glass devitrification by changing the Na/Ca ratio in the glass composition. These results may be interesting for further works to which crystallization may be either a desired or undesired phenomena.
AbstractSynthesis and use of novel compositions of bioactive glasses (BGs) for hard tissue engineering are of important significance in the biomedical field. In this study, we successfully synthesized a series of 58S-based BGs containing fluoride (F−) and silver (Ag+) ions through a sol-gel method for possible use in bone/dental regeneration and antibacterial strategies. Characterizations of samples were performed by using thermal analyses (thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC)), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), textural analysis (N2adsorption-desorption), and morphological observations by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The obtained data revealed that the fabricated BGs are in a glassy state before incubation in the Kokubo’s simulated body fluid (SBF), and an apatite-like layer is formed on their surface after 7 days of immersion in SBF. The size of the glass particles was in the nano-range (about 100 nm or below), and their pore size was in the mesoporous range (15-25 nm). These early results suggest that the F- and Ag-doped glasses show promise as multifunctional bioactive materials for bone/dental tissue engineering.
Abstract Since the discovery of 45S5 Bioglass® by Larry Hench, bioactive glasses have been widely studied as bone substitute materials and, in more recent years, have also shown great promise for producing three-dimensional scaffolds. The development of additive manufacturing techniques and their application in bone tissue engineering allows the design and fabrication of complex structures with controlled porosity. However, achieving strong and mechanically-reliable bioactive glass scaffolds is still a great challenge. Furthermore, there is a relative paucity of studies reporting an exhaustive assessment of other mechanical properties than compressive strength of glass-derived scaffolds. This research work aimed at determining key mechanical properties of silicate SiO2-Na2O-K2OMgO-CaO-P2O5 glass scaffolds fabricated by robocasting and exhibiting a porosity gradient. When tested in compression, these scaffolds had a strength of 6 MPa, a Young’s modulus around 340 MPa, a fracture energy of 93 kJ/m3 and a Weibull modulus of 3, which provides a quantification of the scaffold reliability and reproducibility. Robocasting was a suitable manufacturing method to obtain structures with favorable porosity and mechanical properties comparable to those of the human cancellous bone, which is fundamental regarding osteointegration of bone implants.
AbstractPresent work explores the relationship between the composition, dissolution rate, ion release and cytocompatibility of a series of borophosphate glasses. While, the base glass was selected to be 40mol%P2O5-16mol%CaO-24mol%MgO-20mol%Na2O, three B2O3 modified glass compositions were formulated by replacing Na2O with 1, 5 and 10 mol% B2O3. Ion release study was conducted using inductively coupled plasma atomic emission spectroscopy (ICP-AES). The thermal scans of the glasses as determined by differential scanning calorimetry (DSC) revealed an increment in the thermal properties with increasing B2O3 content in the glasses. On the other hand, the dissolution rate of the glasses decreased with increasing B2O3 content. To identify the effect of boron ion release on the cytocompatibility properties of the glasses, MG63 cells were cultured on the surface of the glass discs. The in vitro cell culture study suggested that glasses with 5 mol% B2O3 (P40B5) showed better cell proliferation and metabolic activity as compares to the glasses with 10 mol% (P40B10) or with no B2O3 (P40B0). The confocal laser scanning microscopy (CLSM) images of live/dead stained MG63 cells attached to the surface of the glasses also revealed that the number of dead cells attached to P40B5 glasses were significantly lower than both P40B0 and P40B10 glasses.
Abstract Sol-gel derived bioactive borate glasses (SGBGs) rapidly convert to hydroxycarbonated apatite (HCA) in simulated body fluid (SBF), in vitro. While previous studies have examined the influence of processing and composition on bioactivity, the effect of the in vitro dissolution media has not been well examined for these glasses. In this study, the mineral conversion of a SGBG substituted 45S5 Bioglass® formulation (“B46”, (46.1)B2O3-(26.9)CaO-(24.4)Na2O-(2.6)P2O5, mol%), was examined in six different dissolution media: SBF, tris(hydroxymethyl)aminomethane (TRIS, pH 7.4) buffer, Dulbecco’s phosphate buffered saline (PBS, 1X), Dulbecco’s Modified Eagle Medium (DMEM, 1X), 0.9% Saline (SAL), and deionized water (DIW) at 1.5 mg/mL for 10 min, 2h, and 1d. All media underwent a rapid increase in pH as a result of glass dissolution and ion release. B46 in SBF, TRIS, and PBS converted to HCA while B46 in DMEM, SAL, and DIW converted to calcite according to attenuated total reflectance-Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The ratio of B46 to SBF was also examined at 3, 6, 12, and 24 mg/mL for 1d. These results help elucidate the dissolution and mineral conversion of borate glasses and help provide insights into optimizing pre-conditioning treatments for both in vitro and in vivo analyses.
