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Bioactive glass coatings: A review
Abstract
Bioactive glasses, discovered by Hench and co-workers at the end of the 1960s, are among the most promising biomaterials for bone repair and reconstruction, mainly thanks to their high bioactivity index. Unfortunately, due to their brittleness and relatively poor mechanical properties, their clinical applications are limited to non-load bearing implants. However, bioactive glasses can be successfully employed as coatings on bioinert metallic substrates, in order to combine high bioactivity with mechanical strength. After a brief introduction to the main properties of biomaterials and bioactive glasses, the present paper provides an overview of the different approaches and available techniques to realise bioactive glass coatings, with a particular emphasis on thermal spray, which is nowadays one of the most popular coating procedures.
... When compared to other materials, bioactive glasses are extremely biocompatible and have a higher probability of integrating with human tissue than metal implants, making them an excellent alternative for increasing the biocompatibility and bioactivity of these metals. Bioactive glass has the following benefits: it can replace injured bone and tissue while also integrating well with the body's environment, it may aid in tissue regeneration, and it degrades at a rate comparable to tissue renewal [4]. When used as a coating material, bioactive glasses can aid in the integration of metal implants into host tissue by producing apatite at the interfaces. ...
... The intensity of this band increases with the increase of Al content. The marked bands in the region of 1000-1100 cm -1 and 560-600 cm -1 is attributed to the P-O bending vibration of the PO 4 3-(phosphate) group which reveals that the presence of crystalline HAp (Ca 10 (PO 4 ) 6 (OH) 2 ) in the nBGC samples after SBF treatment [7,40]. The small peak at~455 cm -1 specifies the bending vibration of Si-O-Si bonds in the silicate network which could be caused by the creation of a silica-rich layer. ...
... Based on the FTIR results, we can conclude that incorporation of Al 2 O 3 into the nBGC sustains a good extent of bioactivity and it promotes the growth of HCA (Hydroxyl Carbonate Apatite) on the glass-ceramic surface. Moreover, the presence of PO 4 3-, CO 3 2-and OH groups in the FTIR spectrum confirmed the growth of the crystalline HCA layer. The acquired results corroborated with XRD analysis and further, it was confirmed by FESEM and EDS analysis. ...
Bioactive glasses have been popular as coating materials on bone implants in recent years to increase their integration with the host tissue and overall biological function. Infection and toxicity are significant factors in the failure of bone-implant material. The goal of this research is to develop a sol-gel derived, Al2O3 doped nanobioactive glass-ceramics (nBGC) with non-toxic and antibacterial activity. The main crystalline phase of sodium calcium silicate was transformed to sodium calcium aluminium silicate by increasing the Al2O3 concentration, it was confirmed by X-ray diffraction (XRD) and Fourier Transform Infra-Red (FTIR) spectroscopy analysis. The density and mechanical strength were increased as 2.63–3.12 g/cm³ and 75–105 MPa, respectively for the sample x = 0 to 10 wt.%. The formation of hydroxyapatite (HAp) was proved by XRD, FTIR, and FESEM (Field Emission Scanning Electron Microscope) with EDS (Energy Dispersive X-ray Spectroscopy) analysis through variations in pH, zeta potential, and degradation behavior. Higher cell viability percentage was attained as >99% for L929 cells, outstanding antibacterial activity against E. coli and S. aureus and excellent hydrophilic nature were obtained for the sample nBGC-10Al. Altogether, a higher concentration of Al2O3 in nBGC could enhance the physical and biological properties and it can be used as an excellent candidate for orthopedic applications.
Graphical abstract
... However, these are susceptible to chemical and electrochemical degradation in the body as the body fluid is aqueous with dissolved oxygen and ions such Cl -1 and OH -1 [1]. Moreover, these metallic materials cannot form any biological or chemical bond at the interface between the implant surface and host tissue which leads to relative movements resulting in to inflammatory reactions [2]. ...
... Thanks to surface modification of materials, it is possible to combine the desired surface properties (bioactivity and ion release) of the surface with the ideal bulk properties such as tensile strength or stiffness of the implants [3]. So an effective approach to avoid unwanted reactions and achieve stronger bonding of the implant with the host tissue is to modify the surface of the implant with coating of desired properties [2]. Selecting the appropriate coating material and coating technique is a major challenge in the production of implants for biomedical purposes. ...
... Materials which are employed in implants and medical devices are called biomaterials. These materials can perform predetermined functions when they interact with a biological system [2]. In particular, the main feature required for a biomaterial is biocompatibility. ...
Thermal spraying of bioglasses offers the opportunity to produce coatings for different biomedical applications. The resorption of the coatings can be adjusted by tailoring the chemical composition of the glass and the coating microstructure. This thesis describes the production of novel bioactive and bioresorbable glass coatings for biomedical applications via an emerging suspension high velocity-oxy fuel (SHVOF) thermal spray. Bioglass® (45S5) was sprayed at the flame power of 90, 75, 50 and 25 kW by varying fuel (hydrogen) and oxygen flow rates. No coating was obtained at the flame power of 90 kW, and thin coating (< 10 µm) was obtained at 25 kW. Thick (25 ± 3 µm) and uniform coatings were obtained at the flame powers of 50 and 75 kW. The 50 kW coating was 16 ± 2 % porous, while the 75 kW coating was 10 ± 1 % porous. The bioactivity tests of the coatings showed that no hydroxyapatite (HA) was deposited on the surface of 25 kW coating even after seven days of immersion in simulated body fluid (SBF). Whilst, the coatings produced at 50 and 75 kW revealed HA deposition after three days. EDX analysis of the cross-section of the coated samples showed that the 50 kW initial coating thickness reduced from 25 µm to 6 µm after immersion in SBF for 7 days, which means that this microstructure was highly reactive towards SBF and hence behaved like a resorbable coating. Coatings from two bioactive glasses, namely ICIE16 (48.0 % SiO2, 33.0 % CaO, 6.6 % Na2O, 2.4 % P2O5 and 10.0 % K2O, in wt %.) and 13-93 (53.0 % SiO2, 6.0 % Na2O, 20.0 % CaO, 12.0 % K2O, 5.0 % MgO and 4.0 % P2O5, in wt %) were successfully produced at the flame powers of 50 and 75 kW. For both formulations, thick, porous and less hard coatings were obtained at 50 kW, whilst harder, dense and less thick coatings were obtained at 75 kW. ICIE16 coatings showed more dissolution in SBF than the 13-93 coatings. Moreover, in-vitro cell tests, using MG63 cells, showed good cell attachment and proliferation on the surfaces of the coating, revealing good cytocompatibility. Resorbable phosphate based glass (PBG), P-40 (40.0 % P2O5, 16.0 % CaO, 24.0 % MgO, 20.0 % Na2O in mol %) was sprayed at 50 and 75 kW flame power. The 75 kW coating was thinner and rougher than the 50 kW coating; both coatings presented globules on the surface. The Raman analysis of the P-40 coatings suggested that the structure of the glass had changed as the concentration of Q2 (2 bridging oxygen)species has been decreased. Whilst, Q1 (1 bridging oxygen) concentration has been increased and Q0 (0 bridging oxygen) species has been formed. Due to these structural alterations, these coatings showed less ion release and mass degradation than those reported in the literature for P-40 thin films and bulk glass. Ga2O3 doped Bioglass® was manufactured for antimicrobial applications and deposited at 50 kW. Moreover, Ga2O3 and Bioglass® suspensions were co-deposited via a hybrid nozzle at 50 kW to mix them in the flame. Both coatings showed bioactivity as HA was deposited on the surfaces of these coatings after immersion in SBF for 3 days. In summary, SHVOF thermal spraying has been proven to be an effective and versatile technique to deposit different bioglasses, maintaining their amorphous tetrahedral structure and composition.
... To date, various surface modifications such as coating with bioactive materials [10,11], such as bioactive glasses (BAGs) and hydroxyapatite (HAP) [12], have been applied to improve the bioactivity of TC4 implants and prolong their life [13], as well as to limit the release of metal ions to the body [14,15]. BAGs and HAP lack mechanical strength for loadbearing applications, however, their osteoconductive and osteoinductive properties make them desirable coating materials for Ti alloy implants in order to combine their high bioactivity with the mechanical strength of metallic implants [3,16,17]. ...
... Compositions (in wt%) of BAGs and coefficient of thermal expansion of BAGs and Ti6Al4V[17]. ...
The restoration of large bone defects caused by trauma, tumor resection, or infection is a major clinical problem in orthopedics and dentistry because postoperative infections, corrosion, and limited osteointegration of metal implants can lead to loosening of the implant. The aim of this study was to improve the surface properties of a 3D-printed (electron beam melting, EBM) Ti6Al4V-based macroporous scaffold by multilayer coating with bioactive silicate glasses (BAGs) and hydroxyapatite doped with a silver (AgHAP) or AgHAP additionally sonochemically modified with ZnO (ZnO-AgHAP). The coated scaffolds AgHAP_BAGs_Ti and ZnO-AgHAP_BAGs_Ti enhanced cytocompatibility in L929 and MRC5 cell lines and expressed bioactivity in simulated body fluid (SBF). A lower release of vanadium ions in coated samples compared to bare Ti scaffold indicates decreased dissolution of Ti alloy in coated samples. The coated samples reduced growth of E. coli and S. aureus for 4 to 6 orders of magnitude. Therefore, the 3D-printed Ti-based scaffolds coated with BAGs and (ZnO-)AgHAP have great potential for application as a multifunctional implant with antibacterial properties for the restoration of defects in load-bearing bones.
... (i) enhancement of bone formation, (ii) direct bonding of the costing with the adjoining bone, and (iii) reduction of metal corrosion as well as the release of corrosion products. Electrophoretic deposition [148], plasma spraying [149], and dip coating [143], [150] have been reported as common fabrication techniques for bioceramics. ...
... ZrO2 (or zirconia) derived from Zr, is commonly used in a number of prosthetic devices owing to its high strength and wear resistance [109]. ZrO2 is also used as a coating on Ti in dental implants [150]. In addition, it has been shown that ZrO2 implants accumulate less bacteria as compared to that of commercially pure Ti implants in vivo [113]. ...
... (i) enhancement of bone formation, (ii) direct bonding of the costing with the adjoining bone, and (iii) reduction of metal corrosion as well as the release of corrosion products. Electrophoretic deposition [148], plasma spraying [149], and dip coating [143], [150] have been reported as common fabrication techniques for bioceramics. ...
... ZrO 2 (or zirconia) derived from Zr, is commonly used in a number of prosthetic devices owing to its high strength and wear resistance [109]. ZrO 2 is also used as a coating on Ti in dental implants [150]. In addition, it has been shown that ZrO 2 implants accumulate less bacteria as compared to that of commercially pure Ti implants in vivo [113]. ...
... Even if BGs may represent ideal osteoinductive and bioresorbable materials for bone tissue engineering applications, their use in load-bearing conditions is strongly limited due to their poor mechanical properties. For this reason, the application of a BG coating may constitute an effective strategy to both enhance osteo-integrative properties of metallic implants and somehow overcome the intrinsic brittleness of BGs [5,200,201]. It is also worth underlining that BG coatings can actively stimulate osteointegration, while other bioceramic coatings, such as HA, are only osteoconductive [202]. ...
... For example, the well-known commercial 45S5 Bioglass® (45SiO 2 -24.5CaO-24.5Na 2 O-6P 2 O 5 wt%) has a TEC value (15 × 10 − 6 • C − 1 ) significantly higher than that of titanium alloys (about 9 × 10 − 6 • C − 1 ) [5]. Ideally, the thermal expansion coefficient of the glass should perfectly match with that of the metallic substrate to avoid the glass pulling away from the implant upon processing [200]. In this regard, several scientists have focused their attention on developing different glass compositions with more suitable TEC for application as coatings. ...
Metallic implants sometimes fail in orthopedic surgeries due to insufficient bio-functionality, implant-associated infections, poor osteointegration due to high inertness (Ti, Co–Cr, stainless steel alloys), and a too fast degradation rate (Mg-based alloys). Bioceramic coatings are among the most appropriate solutions for overcoming these drawbacks. After providing a picture of the history as well as the pros and cons of the different types of metallic implants, this review focuses on bioceramic coatings that can be applied on them, including metal oxides, calcium phosphates, silicates, glasses, glass-ceramics, carbon, etc. Various coating strategies and applications are briefly described and discussed, with emphasis on a selected number of highly promising researches. The major trends and future directions in the development of bioceramic coatings are finally suggested.
... The control of these parameters allows the attainment of resistant coatings with the desired properties. The thickness of the coatings obtained by thermal spraying varies between 50 µm and 2 mm [2]. Several thermal coating processes are currently available, and are illustrated in Figure 1. ...
... The covering material is fed in a powder form on the substrate surface and melted using laser, eventually forming the coating, as represented in Figure 5. Several changes to this coating technique are currently being developed. In an industrial installation, the powder is fed through a nozzle and the laser beam is directed towards the powder, melts it, and forms the coating [2,118]. ...
Diseases or complications that are caused by bone tissue damage affect millions of patients every year. Orthopedic and dental implants have become important treatment options for replacing and repairing missing or damaged parts of bones and teeth. In order to use a material in the manufacture of implants, the material must meet several requirements, such as mechanical stability, elasticity, biocompatibility, hydrophilicity, corrosion resistance, and non-toxicity. In the 1970s, a biocompatible glassy material called bioactive glass was discovered. At a later time, several glass materials with similar properties were developed. This material has a big potential to be used in formulating medical devices, but its fragility is an important disadvantage. The use of bioactive glasses in the form of coatings on metal substrates allows the combination of the mechanical hardness of the metal and the biocompatibility of the bioactive glass. In this review, an extensive study of the literature was conducted regarding the preparation methods of bioactive glass and the different techniques of coating on various substrates, such as stainless steel, titanium, and their alloys. Furthermore, the main doping agents that can be used to impart special properties to the bioactive glass coatings are described.
... Bioactive glass (BG) 45S5 is a common object of materials research, considering its versatility and high performance in biomedical applications in comparison with borate, phosphate, and other doped glasses [1,2]. The composition of (45SiO 2 -24.5Na 2 O-24.5CaO-6P 2 O 5 wt. ...
The integration of bioactive glasses (BGs) into hard tissues in in-vivo models can be evaluated through X-ray radiographs. The image contrast plays an important role and should be enhanced to improve accurate minimal invasive diagnostics of the performance of BGs containing implants after surgery. The present work shows the effect of the progressive addition of Bi2O3 (up to 12.2 wt%) on the structure, thermal properties, radiopacity, and bioactivity of 45S5-like BG obtained by quenching of the melt prepared from oxide precursors. The BG chemical composition, phase composition, structure, chemical state, thermal properties, and radiopacity were respectively investigated by X-ray fluorescence (XRF), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), and radiopacity analysis according to the ISO13116:2014 norm. The bioactivity of the glasses was monitored by immersing them in a simulated body fluid (SBF) under static conditions. The apatite formation ability and ion concentration in SBF after 3, 7, 14, and 21 days were investigated by XRD, scanning electron microscopy (SEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), and ICP mass spectrometry (ICP-MS). All samples were found to be X-ray amorphous. Simultaneous formation of [BiO3] and [BiO6] units is noted in the BG. The glass radiopacity increased up to 1.8 and 4.2 times compared to the reference glasses without Bi2O3. Bi2O3 additions in the glass slow down the formation of apatite-like structures as a result of the network forming role of [BiO3] and [BiO6] units in the BG. Nevertheless, the BGs with the 12.2 wt % Bi2O3 still shows the ability to form apatite deposits after 7 days of immersion in simulated body fluid (SBF).
... The increase in voltage enhanced particle mobility, and coarser particles flow toward the surface. 66 For instance, Boccaccini et al. succeeded in producing bioactive composite coatings of CS/45S5 BG on SS substrate and studied the influence of EPD electric voltage on deposition yield. 24 Potentiodynamic polarization curves demonstrate the positive impact of the applied surface modification on improving the corrosion resistance of 316SS substrate. ...
This study investigated the potential of 316L stainless steel coated with bioactive glasses for orthopedic implants by analyzing their corrosion resistance. To achieve this goal, novel bioglass compositions (BGs) were synthesized using the hydrothermal method and characterized using various techniques, including FTIR, XRD, SEM-EDS, and BET. The results confirmed that the bioglasses were amorphous and had surface porosity with a nanometric average size of about 40 to 47 nm. The bioglasses' bioactivity was assessed by immersing them in simulated body fluid (SBF) for up to 14 days. The 15-7510P bioglass displayed the highest acellular bioactivity, as evidenced by the rapid formation of a thick and continuous apatite layer on bioactive glass particles. Furthermore, the electrochemical corrosion behavior of 316L stainless steel substrate coated with bioactive glasses was evaluated using polarization and impedance in SBF solution at 37°C and significantly improved compared to virgin 316 SS. The results showed that at 30V with 0.5 g/l of Cs, 4 g/l of BG, and a deposition time of 10 min, the corrosion resistance of 316 SS was improved by the bioactive glass 15-7510P/ Chitosan coating composite. Cell viability and cytotoxicity of bioactive glasses were also analyzed using DPSCs and GMSM-K. The results demonstrated that the bioactive glasses had no harmful effects on cell viability.
... Bioactive glass is a material that can replace damaged tissues and promote tissue regeneration. It is also a good promising candidate for the integration of metal implants 35 . Bioglass composites are commonly used as coating materials due to their various properties such as mechanical strength, bioactivity, and surface functionality 12 . ...
Bioceramics are the ceramics that are usually composed of zirconia, alumina, hydroxyapatite, tricalcium phosphate,
bioglass, etc., Bioceramics are used in various biomedical applications because of positive interactions with human tissues.
Medicine, dentistry, surgery, and tissue engineering are different field that use bioceramics to initiate potential treatment
choices to reinforce the conventional dental and medical practices. Gradually, bioceramics have been established for usage
in numerous applications including hip and knee replacement, cardiovascular valve replacements, dental restorations, and
implants. Interestingly, bioceramics is gaining wide attention especially for hip and knee implants due to their ability to
repair and reconstruct damaged or diseased parts of Musculo-skeletal system. Both synthetic and natural bioceramics are
promising as prompt to strongly bind to bone and emerge as a substitute to other metal implants. The major objective of
bioceramic research was the dormancy to prevent biological rejection and interaction of foreign body with functional
biomaterials within the body. Currently, bioceramic materials casted for repairing and reconstruction of soft and hard tissues
can be classified based on composition, structure and properties. The bioinert ceramics are the ones categorized as zirconia
and alumina, glass-ceramics and bioglass, and calcium phosphates-based materials that are bioresorbable. Various
properties of bioceramic properties and recent clinical trials are also contemplated as an update. On the basis of rigorous
requirements in the field of clinical application, developing advanced functional bioceramics for tissue engineering are
considered as future prospect. Thus, current review discusses on various biomedical applications of bioceramics, but majorly
focuses on role of different bioceramics in hip and knee replacement.
... Cancer cells are killed by this heating process while normal cells are regenerate ( Figure 9-D) [20]. performance, which can be challenging if the composition and processing are complex [154,155]. ...
At least 25 bioactive glass (BG) medical devices have been approved for clinical use by global regulatory agencies. Diverse applications include monolithic implants, bone void fillers, dentin hypersensitivity agents, wound dressing, and cancer therapeutics. The morphology and delivery systems of bioactive glasses have evolved dramatically since the first devices based on 45S5 Bioglass®. The particle size of these devices has generally decreased with the evolution of bioactive glass technology but primarily lies in the micron size range. Morphologies have progressed from glass monoliths to granules, putties, and cements, allowing medical professionals greater flexibility and control. Compositions of these commercial materials have primarily relied on silicate-based systems with varying concentrations of sodium, calcium, and phosphorus. Furthermore, therapeutic ions have been investigated and show promise for greater control of biological stimulation of genetic processes and increased bioactivity. Some commercial products have exploited the borate and phosphate-based compositions for soft tissue repair/regeneration. Mesoporous BGs also promise anticancer therapies due to their ability to deliver drugs in combination with radiotherapy, photothermal therapy, and magnetic hyperthermia. The objective of this article is to critically discuss all clinically approved bioactive glass products. Understanding essential regulatory standards and rules for production is presented through a review of the commercialization process. The future of bioactive glasses, their promising applications, and the challenges are outlined.
... Glass substrates are available in larger sizes (>100 cm), while their thickness can be as small as 50 μm, making them an economical substitute for silicon [7][8][9]. Owing to mechanical strength, the chances of warpage are also lower when the glass is used as an interposer substrate [10,11]. Metallization of the glass is often required for many industrial applications. ...
This article reviews the state-of-the-art electroless copper deposition on glass substrates and the associated challenges.The well-known issue of poor adhesion of electroless copper with the glass substrate was addressed and later, improved bymodifying the surface energy using a specific chemical treatment or by creating localized surface roughening. Localized surfaceregions in the glass were created by abrasive-based ultrasonic machining and high-temperature electrochemical-discharge machiningtechniques. The effect of critical process parameters on the surface roughness and morphology was explained. Both qualitative andquantitative adhesion measurement techniques, such as cross-hatch tests and 90°/180° peel adhesion tests, were presented. Theadhesion strength is affected by the surface roughness of the substrate and residual stress build-up in the film. As the build-up stresscan be released by the post-deposition annealing, the adhesion strength is further increased. Finally, the electroless coppertechnology in making through-glass-vias and embedded redistribution lines are presented.
... improve the overall performance of the medical device while bringing valuable benefits to the patient [161][162][163]. ...
Dental glass-ceramics (DGCs) are developed by controlled crystallization of oxide glasses and form an important group of biomaterials used in modern dentistry. They are also of great importance to scientists studying the fundamentals of crystallization. DGCs must meet strict requirements for restorative prostheses and to streamline the workflow for dentists and increase patient comfort. Considerable research has been devoted to developing new DGCs using advanced technologies, such as CAD/CAM or 3D printing, and to improve material properties. DGCs are designed to have exceptional aesthetics, translucency, high strength, chemical durability, wear resistance, biocompatibility, low thermal conductivity, and hardness similar to that of natural teeth. Some are also bioactive to stimulate a favorable response from the tooth and supporting bone. This allows treatment of hypersensitivity, regeneration of alveolar bone, and healing of periodontal tissues. In this comprehensive and critical review, we compare (inert) restorative prostheses and bioactive GCs. We elaborate on the relevant theoretical fundamentals of crystallization in oxide glasses and explain key technologies to fabricate DGCs. Advanced experimental techniques to unveil the details of crystallization in DGCs are thoroughly discussed. Finally, we propose a strategy for adopting advanced technologies, characterization tools, theoretical insights, and computer models to advance this important field.
... Nowadays, one of the most preferred Ti alloys as implant material is Ti6Al4V alloy [4]. Due to the Ti6Al4V alloy's bioinert nature, its surface can be coated with various bioactive materials to increase its biocompatibility with the surrounding tissues [5][6][7]. The most widely used bioactive material for this purpose is hydroxyapatite (HA) [8]. ...
In this study, the effect of thermal oxidation treatment on Ti6Al4V alloy in the HA coating by Electrophoretic Deposition (EPD) technique was investigated. For this purpose, the HA powders were produced by chemical precipitation method and characterization studies of produced hydroxyapatite powders were carried out by X-Ray Diffraction (XRD), and powder size analysis. Then, thermal oxidation process was applied to Ti6Al4V samples at different temperatures. The surface roughness of Ti6Al4V samples were measured in order to determine the thermal oxidation effect on Ti6Al4V surface. Then, HA coating was pruduced on Ti6Al4V at the determined voltage and time by EPD process. HA deposition efficiency on Ti6Al4V was determined according to thermal oxidation process. The obtained results showed that the thermal oxidation process affects the coating efficiency positively.
... Materials used for load bearing tailor-made implants most commonly include stainless steel (SS) and titanium based alloys which however, are largely bio-inert. Hence, coatings of Bio-glass, and bio-glass ceramic composites on metal and metal alloys have found wide application, particularly in the field of artificial bones [6][7][8]. Following this approach, while the metal or metal alloys provide the necessary mechanical strength and stability to the bone implants, the bio-glass based coatings enable improved and easy bio-integration of such implants within the human body via their interaction with the surrounding living tissues. ...
Experimental results and theoretical simulation of material ablation on nanosecond Nd:YAG laser irradiation of bioactive glass targets, is presented. The process of pulsed laser ablation critically affects both, laser based surface modification and pulsed laser deposition (PLD) of bioactive glass (BG). A thermal model based theoretical simulation has been carried out describing heat-transport, melting and vaporization of a laser irradiated BG target under near-threshold ablation conditions. Calculated mass ablation rate per laser pulse has been compared with our experimental observations over the average laser fluence of 0.5J/cm² to 6J/cm². With increasing laser fluence, possibility of material ablation approaching phase explosion has been discussed by comparing the calculated maximum temperature reached by the laser irradiated target and the estimated thermodynamic critical temperature for BG. Our investigations indicate that with average laser fluence restricted to ∼5 J/cm² material ablation occurs largely via normal vaporization ensuring deposition of an uniform, homogeneous BG coating through PLD. Target surface temperatures estimated from our calculations also suggest that laser based surface modification of BG can be reproducibly carried out without causing target crystallization and surface damage through crater formation for irradiating laser fluence in the region of ∼ 5J/cm².
... tough bioactive implants (e.g. bio glass-ceramics) [33,34], coatings [35], composites [36], hybrids [37], and cancer treatment [38,39]. Finally, in addition to several scientific journals dedicated to biomaterials, there is even a dedicated periodical called Biomedical Glasses [40]. ...
Future research is envisaged in which the compositional and microstructural design, synthesis, characterization, and application of biomaterials can be significantly accelerated by theoretical and computational modeling. In the last 25 years, more than 6000 articles and 100 review papers have highlighted the importance of discovering bioactive glasses (BGs) on biomaterials research and development pathways. We applaud these accurate portrayals of the early days after discovering Bioglass® by Larry Hench in 1969, the chronology, numerous advances, and future challenges. However, as the literature became very rich in this topic, very few works have addressed model‐driven approaches to design new BGs or efficiently predict their properties. This task should be accelerated as a key part of the macro endeavor to decode the “glass genome.” This chapter reviews seminal publications that have applied molecular dynamics (MD) simulations – the only vastly studied computational modeling of BGs – for understanding BGs and glass‐ceramics. We believe with the growing acquired knowledge on the properties of glasses, experimental data, force field development, and computational power, the prospects for MD simulations of complex problems and predicting the surface interactions and biological responses are possible in the future.
... Also some investigations have been conducted to achieve accurate bio ceramic glass coatings using a variety of methods, including enamel coating, magnetron sputtering, laser adhesive, and heat treatment. [64][65][66] This review focuses on dental ceramic materials and manufacturing processes; hence the work provides a comprehensive review of the past, the current state of the art of ceramic glasses for dental applications, materials used during manufacturing processes, mechanical properties, biocompatibility and also outlines important research focuses that can be used in the years to come. This review also presents an in-depth sight of parameters with various experimental findings of these techniques. ...
In the era of biomaterials evolution, ceramic materials are playing a notable role in dental practices. Ceramics have been used in dental applications for several decades because of its important properties such as suitable biological incorporation into human body, surface colouration, enhanced surface morphology, mechanical characteristics, physiochemical integration, durability and lifespan. There are numerous complications in the fabrication and production of ceramics by manufacturers. Therefore, much research and development has been performed to further improve and understand the manufacturing mechanisms which occur on the ceramic materials. These efforts are aimed at not only improving the fundamental understanding of the material but also helping to meet customer satisfaction and quality of production. This review article mainly provides insight on the various ceramic materials with a focus on their properties including stability, strength, and heat resistance. It is corroborated with a detailed account of various ceramic fabrication processing techniques with their applications that include sol-gel casting, hot pressing and phase inversion methods. In summary, some critical suggestions as well as detailed scope of future aspects and frontiers have been outlined to provide robust improvements for research and development platforms.
... C.p. Ti substrates were coated with a combination of two different bioglasses, Bioglass ® 45S5 and Bioglass ® 1393, both commercially available (supplied by SCHOTT Vitrixx). Bioglasses were amorphous powder as received, with a mean particle size of d [50] = 4.5 µm and d [50] = 6.1 µm for BG 45S5 and BG 1393, respectively [55]. The chemical composition of BG 45S5 is 45 wt.% SiO 2 , 24.5 wt.% CaO, 24.5 wt.% Na 2 O and 6 wt.% P 2 O 5 [35], while for BG 1393 it is 53 wt.% SiO 2 , 20 wt.% CaO, 6 wt.% Na 2 O, 4 wt.% ...
The use of porous titanium samples fabricated by space-holder powder metallurgy with
bioactive coatings has already been reported to prevent resorption of the bone surrounding the implant and improve osseointegration, respectively. However, the presence of pores as well as the poor adherence and the brittle behavior inherent to glassy coatings affect the service behavior of implants fabricated from these samples. Therefore, they need to be optimized. In this work, 50 vol.% of porosity titanium substrates were manufactured with different pore range size (100–200 and 355–500 �m) spacer particles and coated with a bilayer of bioactive glasses (45S5/1393). The effect of
the pores on the tribomechanical properties and infiltration of the bioactive glass 1393 along with the bioactivity of the bioactive glass 45S5 were evaluated by instrumented micro-indentation and scratch tests and the formation of hydroxyapatite in simulated body fluid. The results obtained were very promising as potential implants for the replacement of small tumors in cortical bone tissues, mainly due to the smaller pores that present an improved biomechanical and biofunctional balance.
... However, bioactive agent coatings precipitate and wear over time. Moreover, the brittleness and relatively poor mechanical properties of the coatings limit their clinical application to non-load-bearing implants [16]. Modification of the surface morphology gives PEEK unique surface characteristics and improves the hydrophilicity of the surface that has a direct impact on the initial adhesion of bone marrow stem cells to the surface and subsequent proliferation and differentiation behavior [17]. ...
Polyetheretherketone (PEEK) is a potential substitute for conventional metallic biomedical implants owing to its superior mechanical and chemical properties, as well as biocompatibility. However, its inherent bio-inertness and poor osseointegration limit its use in clinical applications. Herein, thin titanium films were deposited on the PEEK substrate by plasma sputtering, and porous nanonetwork structures were incorporated on the PEEK surface by alkali treatment (PEEK-TNS). Changes in the physical and chemical characteristics of the PEEK surface were analyzed to establish the interactions with cell behaviors. The osteoimmunomodulatory properties were evaluated using macrophage cells and osteoblast lineage cells. The functionalized nanostructured surface of PEEK-TNS effectively promoted initial cell adhesion and proliferation, suppressed inflammatory responses, and induced macrophages to anti-inflammatory M2 polarization. Compared with PEEK, PEEK-TNS provided a more beneficial osteoimmune environment, including increased levels of osteogenic, angiogenic, and fibrogenic gene expression, and balanced osteoclast activities. Furthermore, the crosstalk between macrophages and osteoblast cells showed that PEEK-TNS could provide favorable osteoimmunodulatory environment for bone regeneration. PEEK-TNS exhibited high osteogenic activity, as indicated by alkaline phosphatase activity, osteogenic factor production, and the osteogenesis/osteoclastogenesis-related gene expression of osteoblasts. The study establishes that the fabrication of titanate nanonetwork structures on PEEK surfaces could extract an adequate immune response and favorable osteogenesis for functional bone regeneration. Furthermore, it indicates the potential of PEEK-TNS in implant applications.
... In Fig. 5 SEM images of all sample's surfaces were included in relation with immersion time. SEM micrographs of BG samples immersed in PBS showed some spherical structures that, compared to other images in the literature, appear to be spherulites of HA, mainly for BG1 [27]. However, this result suggest that HA is formed but in too small amount to be identified by XRPD analysis. ...
Background
The bioactive glasses (BGs) are very attractive materials increasingly used in healing skin lesions due to their antibacterial effect and stimulation of collagen deposition and angiogenesis. In this study, three specimens of bioactive glasses (BG1, BG2 and BG3) have been synthesized and characterized.
Methods
In order to evaluate theirin vitro bioactivity, the pH measurements, zeta potential and the concentration of Ca²⁺ and fluor ions released after immersion in phosphate buffered saline (PBS) followed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, inductively coupled plasma optical emission spectrometry (ICP-OES) and for BG1 and BG3, X-ray powder diffraction analysis, were performed. X-ray photoelectron spectroscopy (XPS) was also used for detection of different ions in the solid bioglasses before immersion in PBS. The impact of BG1 and BG3 on skin healing mechanisms was evaluated by oxidative stress and matrix metalloproteases (MMP)-2 and -9 and by histopathological analysis.
Results
The results have shown that all the BGs tested are characterized by a very high degradation rate and a very fast Ca²⁺, fluor and boron releases and displayed changed surface morphology at SEM, after 7 and 14 days of immersion in PBS. In addition, BG1 and BG3 reduced in vivo the lipid peroxidation, increased the nitric oxide, especially at 14 days and improved superoxide dismutase activity, mainly in BG1 treated animals. In parallel, both BG1 and BG3, diminished MMP-9 at 14 days and increased the proportion of normal collagen in the bed of the wound, particularly BG3.
Conclusion
These results suggested that due to the antioxidant and anti-inflammatory properties of components released from BGs and regulatory properties on MMPs activities, BGs can exert beneficial effects in wound healing.
... Since ceramics are generally hard and brittle and have poor fatigue properties, they are less suitable for load-bearing applications. However, bioactive materials, such as HA and bioglass, are common materials to use as bioactive coatings on metallic implants for load-bearing applications [39,40]. Ceramic coatings on metal implants have three major benefits: they (1) enhance the formation of bone, (2) allow direct bonding with bone, and (3) reduce metal corrosion as well as related corrosion product release. ...
Biomaterials are in high demand due to the increasing geriatric population and a high prevalence of cardiovascular and orthopedic disorders. The combination of additive manufacturing (AM) and biomaterials is promising, especially towards patient-specific applications. With AM, unique and complex structures can be manufactured. Furthermore, the direct link to computer-aided design and digital scans allows for a direct replicable product. However, the appropriate selection of biomaterials and corresponding AM methods can be challenging but is a key factor for success. This article provides a concise material selection guide for the AM biomedical field. After providing a general description of biomaterial classes—biotolerant, bioinert, bioactive, and biodegradable—we give an overview of common ceramic, polymeric, and metallic biomaterials that can be produced by AM and review their biomedical and mechanical properties. As the field of load-bearing metallic implants experiences rapid growth, we dedicate a large portion of this review to this field and portray interesting future research directions. This article provides a general overview of the field, but it also provides possibilities for deepening the knowledge in specific aspects as it comprises comprehensive tables including materials, applications, AM techniques, and references.
... In clinics, BGs have been widely employed in form of fine powders and particulates, especially in dentistry and orthopedics, where their use is firmly established since many years due to their ability to promote bone remineralization [7], as well as their enormous potential as bioactive coatings on inert metal implants [8][9][10]. as a function of the sintering temperature by combining mathematical modeling and experimental measurements of intrinsic permeability supported by tomographic characterization [33]. ...
The intrinsic brittleness of bioactive glasses (BGs) is one of the main barriers to the widespread use of three-dimensional porous BG-derived bone grafts (scaffolds) in clinical practice. Among all the available strategies for improving the mechanical properties of BG-based scaffolds, strut densification upon sintering treatments at high temperatures represents a relatively easy approach, but its implementation might lead to undesired and poorly predictable decrease in porosity, mass transport properties and bioactivity resulting from densification and devitrification phenomena occurring in the material upon heating. The aim of the present work was to investigate the sinter-crystallization of a highly bioactive SiO2-P2O5-CaO–MgO–Na2O–K2O glass (47.5B composition) in reference to its suitability for the fabrication of bonelike foams. The thermal behavior of 47.5B glass particles was investigated upon sintering at different temperatures in the range of 600–850 °C by means of combined thermal analyses (differential thermal analysis (DTA) and hot-stage microscopy (HSM)). Then, XRD measurements were carried out to identify crystalline phases developed upon sintering. Finally, porous scaffolds were produced by a foam replica method in order to evaluate the effect of the sintering temperature on the mechanical properties under compression loading conditions. Assessing a relationship between mechanical properties and sintering temperature, or in other words between scaffold performance and fabrication process, is a key step towards the rationale design of optimized scaffolds for tissue repair.
... Forming a bioactive glass coating layer on the surface of titanium alloy scaffolds is another strategy to improve surface osteogenic activity. It has been applied onto titanium alloy substrates by using the thermal spraying method and others, enabling titanium alloy scaffolds to have enhanced biological activity [26]. Mesoporous bioactive glass (MBG) is one of the most extensively studied silicate biomaterials, due to its unique structure and composition [27,28]. ...
Titanium alloy scaffolds have recently gained substantial interest for the treatment of critical-size bone defect, particularly along with the maturity of the 3D printing technology that is capable of turning scaffold design ideas into real implants. As titanium alloys lack surface osteogenic activity, for improved biological performance of such scaffolds, surface modification is necessary. Various coating materials and coating methods have been explored. In this study, we developed a unique surface modification method to provide the surface of 3D printed titanium scaffolds with nano-sized structure and bioactive agent. Uniform, ordered TiO2 nanotube arrays were formed by applying two-step anodization, and then mesoporous bioactive glass (MBG) was loaded into nanotubes. The results of in vitro immersion testing showed that bioactive ions, i.e., Si and Ca ions, could be steadily and continuously released from MBG into basal medium. The assessment of the responses of hBMSCs confirmed that the surface-modified scaffolds supported the adhesion and proliferation of hBMSCs, indicating good surface cytocompatibility. The developed method of combining surface nanostructure and bioactive agent could be used as a new strategy to improve the osteogenic activity of 3D printed titanium alloy scaffolds.
... Although various implant coating deposition methods, alternative to the commercial solution (i.e., plasma spray), have been promoted through various research channels [46,86], the large-area uniformity of the deposited layers is generally overlooked. As this aspect is technological relevant, we have further oriented our work towards probing if and how a laboratory-grade RF-MS system could be used in a microproduction-type regime. ...
Currently, there is a considerable time-lag in the industrialization of innovative technological solutions for the functionalization of osseous implants, with ever-demanding healthcare requirements (e.g., controlled release of therapeutic ions, match of biomaterial degradation – bone growth rates, antimicrobial efficiency). As third-generation biomaterials, phosphate bio-glasses (PBGs) have demonstrated an ability to stimulate specific biological responses from tissue to molecular level, by successfully coupling bioactive and resorbable material properties. Here, radio-frequency magnetron sputtered (RF-MS) PBGs were explored as sacrificial resorbable layers for prospective biomedical implant designs. A PBG powder with a 50–P2O5, 35–CaO, 10–Na2O and 5–Fe2O3 composition (mol%) was used as source (target) material. The influence of the argon working pressure (0.2 – 1 Pa) – one of the most prominent RF-MS variables – on the morphology, structure, uniformity, composition, degradation rate and cytocompatibility of PBG films was investigated. The engineered modification of physical-chemical and biological features of the PBG sputtered films was multi-parametrically surveyed by AFM, EDXS, spectroscopic ellipsometry, GIXRD, FTIR spectroscopy measurements and in vitro assays. Results suggested that the film thickness, composition, density and structure were preserved over a uniformity region having a diameter of ~30 mm, irrespective of sputtering pressure. The network connectivity and the surface porosity of the films were found to have antagonistic roles with respect to the in vitro degradation performance. The possibility of fine tuning the composition, structure and thereby biological interaction of the PBG films by conveniently modifying the sputtering pressure was shown (i.e., permitting their complete controlled degradation, without cytotoxic effects). As this work is the first to show in vitro cytocompatibility outcomes of and their cross-area uniformity, could prove to be an important technological step in their future biomedical application and suggest implications for future industrial scale-up.
... Another drawback of Bioglass, used as surface coatings, is the mismatch between thermal expansion coefficient (TEC) and the substrate on which they are applied. So, it is clear that in future, the improvement of TEC and degradation rate of Bioglass will be a challenge [129][130][131]. ...
An unbelievable revolution happened in medical science during the late '60s. A casual conversation with a colonel led Larry Hench to the invention of a biomaterial that is more biocompatible, biodegradable, and bioactive, which was named as Bioglass. The material started its journey with its application in the replacement of ossicles in the middle ear, and today Bioglass is dominating in major medical fields like bone tissue engineering, drug delivery, dentistry, and so on. The wide range of applications and such bio-friendly properties of the material also convey a message that this material is a promising area to work in the field of research. Bioglass is synthesized by two methods i) melt quenching and ii) sol-gel. We aim to help new optimistic researchers in uplifting their interest to conduct researches with this auspicious biomaterial. This paper provides a bird's eye view of the history, preparation process, composition of different bioactive glasses and their biological feedback, biocompatibility mechanism, fundamental properties, noteworthy applications, possibilities along with the shortcomings of Bioglass. The shortcomings of Bioglass are elaborated so that the researchers can explore more about those limitations. We have also depicted the chronological advancements of bioglasses over the years. We believe that the prospects of more advanced researches with Bioglass can bring more success in the modern biomedical world.
Alkali and alkaline earth elements play a crucial role in the structure, processing, and properties of bioactive glasses, widely used in medical applications since their inception in 1969.
Bioactive glasses (BGs) are ideal biomaterials in the field of bio-restoration due to their excellent biocompatibility. Titanium alloys are widely used as a bone graft substitute material because of their excellent corrosion resistance and mechanical properties; however, their biological inertness makes them prone to clinical failure. Surface modification of titanium alloys with bioactive glass can effectively combine the superior mechanical properties of the substrate with the biological properties of the coating material. In this review, the relevant articles published from 2013 to the present were searched in four databases, namely, Web of Science, PubMed, Embase, and Scopus, and after screening, 49 studies were included. We systematically reviewed the basic information and the study types of the included studies, which comprise in vitro experiments, animal tests, and clinical trials. In addition, we summarized the applied coating technologies, which include pulsed laser deposition (PLD), electrophoretic deposition, dip coating, and magnetron sputtering deposition. The superior biocompatibility of the materials in terms of cytotoxicity, cell activity, hemocompatibility, anti-inflammatory properties, bioactivity, and their good bioactivity in terms of osseointegration, osteogenesis, angiogenesis, and soft tissue adhesion are discussed. We also analyzed the advantages of the existing materials and the prospects for further research. Even though the current research status is not extensive enough, it is still believed that BG-coated Ti implants have great clinical application prospects.
Bioactive glasses (BGs) are known for their selective ability to (i) form a mechanically strong interfacial bond with hard (bone) or soft tissues (gingivae or cartilages) (i.e., silica-, silica-phosphate-, phosphate-, borate-phosphate-, or silica-phosphate-borate-based BGs); or (ii) serve as reservoirs for fast-release of therapeutic (osteogenic, angiogenic, anticarcinogenic, or antimicrobial) ions (i.e., phosphate-based BGs and mesoporous BGs). The strength of the bone bond yielded by the osteoproductive-capable BGs is generally equivalent to, or higher than the bone strength. The resorbability of phosphate-based BG is dependent on the content of network formers and cross-linkers. All BGs elicit excellent biochemical compatibility. However, their fracture toughness is typically less than and the elastic modulus is greater than those of bone, indicating that most BGs have suboptimal biomechanical compatibility when used in load-bearing applications. One promising approach to overcome this problem is the development of BGs in coating form, applied to the surface of load-bearing endosseous implants. This work critically assesses BG thin-layers fabricated by the radio-frequency magnetron sputtering method, an industry-ready large-scale physical vapour deposition technology. It is demonstrated that, despite the relative lack of attention paid to this technology, it enables the development of unique BG coatings with efficacious therapeutic capabilities. Here, we present an overview of the most relevant developments achieved thus far, along with the remarkable advantages, drawbacks to overcome, and future perspectives with the intention of highlighting the vast possibilities of this specific field of research.
A facile synthesis method was developed to synthesize TiO2-SiO2-P2O5/CaO or TiO2-SiO2-P2O5/ZnO with a core-shell structure. The carboxylic cation exchanger Tokem-250 has a high selectivity for Ca2+/Zn2+ ions and was used in this study. The framework of the material in the shell was TiO2-SiO2-P2O5, and the inner part was filled with CaO (sample TiO2-SiO2/CaO) or ZnO (sample TiO2-SiO2-P2O5/ZnO). A stepwise heat treatment (drying in a drying oven at 60 °C for 30 min, then annealing in a muffle furnace for 30 min at 150, 250, and 350 °C, at 600 °C for 6 h, and at 800 °C for 1 h) was needed to obtain a homogeneous material. The poly(vinyl alcohol) was used as a binding additive. The obtained composites were characterized by a regular structure and highly developed surface. The samples exhibit bioactive properties in the simulated body fluid (SBF) solution, since the surface contains active centers (Si4+, Ti4+) which contribute to mineralization and precipitation of the calcium-phosphate compounds on the surface from biological media. The TiO2-SiO2-P2O5/CaO-PVA samples did not exceed acceptable hemolysis levels for medical materials.
Coating surfaces with bioactive glass was identified as depositing fine bioactive glasses on biomaterial substrates. Cobalt chrome (Co-Cr) was a viable alternative to stainless steel for long-term applications with superior ductility. Their mechanical properties are explained with high-strength biomaterials for elastic models of 220 to 2300 GPa, more significant than the 30 GPa of bones. The goal of combining metals and bioactive glass has resulted in high biocompatibility and improved bioactivity of the implant’s surface. In addition, it triggers new bone tissue to regenerate throughout osteogenesis and mineralization. However, implantation failure still occurs and requires surgery revision due to a lack of adequate bone bonding and delamination at the coat’s surface layer of the implant. The current review summarizes the coating's adhesion between bioactive glass and Co-Cr substrate applied through Electrophoretic deposition (EPD).
Novel bioactive glass (BG)/hydroxyapatite (HAP) composites were successfully manufactured by electrostatic spray deposition (ESD) to improve the overall osteointegration of Ti6Al4V-based implants. Herein, we combined the high bioactivity of the S58 formulation with the long-term stability of HAP. Highly porous coral-like S58 BG coatings with different thicknesses (6 and 30 μm) were deposited on the top of a thin (150 nm) and dense nanocrystalline HAP layer starting from homogeneous liquid precursor solutions by ESD. In vitro studies were carried out by immersion in simulated body fluid (SBF) solution and compared with single-layered coatings of S58 and HAP. The SBF test revealed that the presence of the BG-topcoat layer significantly improves the reactivity in terms of mineralization response compared to single-layered HAP coating. Furthermore, the S58 coating thickness was found to influence the biological response. The thinner composite is suggested to have a better mineralization performance than the thicker one.
The skeletal system is the most important component of our body that gives shape to our body, keeps it alive, and protects our internal organs against external impacts. When skeletal system is damaged , it can regenerate itself, but if the damage is big and severe, it cannot be regenerated by normal physiological processes. Therefore, bone damage requires scaffolds to improve healing process. The purpose of bone tissue engineering is to restore, regenerate, improve and maintain the function of damaged bone tissue through a combination of cells, biomolecules, and scaffolds. In order to repair and functionalize the bone tissue, scaffolds that mimic the structure of bone mineral and adapt to the cell are prepared. Metals, ceramics, polymers, and composite materials are used as biomaterials in the production of scaffolds. Among these, bioactive glasses, which are in the class of biologically used ceramics (bioceramics), draw attention. Various biomaterials and manufacturing techniques for scaffold provide achievable advances in bone tissue regeneration. Bioactive glass (BG) can form a strong bond with bone by forming a layer of apatite on its surface. They have important properties such as bone conduction, bone inducibility, biocompatibility, and bioactivity. BG can stimulate gene expression that regulates bone formation by releasing ions from its surface. They are mainly composed of silicon, sodium, calcium and phosphate components. When transplanted into the human body, it binds to bone through the hydroxyapatite layer formed on the surface and reacts with surrounding tissues to form a strong mechanical interface bond between the host tissue and the implant. These properties make BG an important potential material in bone tissue regeneration. BG has been widely used to process skeletal structures with or without one or more biopolymers to proper scaffold. Bioactive glass nanoparticles (BGNP) have also grown significantly in bone tissue engineering applications duetoimportantpropertiessuchasverylargespecificsurfacearea, small size, and high surface area to volume ratio. BGNP can be mainly obtained by conventional melt quenching or sol-gel methods. BGNP has applications for soft tissue regeneration/repair and other biomedical applications as well as being particularly interesting biomaterials for bone-related applications.
The development of bioactive glasses, which began with the Hench’s invention of Bioglass®, has considerably advanced over the past 20 years toward the creation of materials that not only chemically bond to living tissue, but also promote tissue regeneration. Some inorganic ions have the effect of stimulating cells and promoting biological functions, including bone formation. Glass-based materials have a significant advantage in the controlled release of inorganic ions because their compositions can be chosen systematically. Stimulating cells and improving therapeutic effects via the inclusion of various inorganic ions released from bioactive glass may represent a key strategy in the development of advanced biomaterials. This paper briefly reviews the research work related to bioactive glasses designed for tissue regeneration undertaken in the past two decades.
The effect of some modifier oxides (MO) which are Li2O, MgO, ZnO and CaO on the radiation shielding features of B2O3–SiO2–Na2O–ZrO2-MO (BSNZ-MO) glasses were studied by using Geant4 Monte Carlo and the results were theoretically compared by using Phy-X/PSD software between 0.1 MeV and 10 MeV energies. BSNZ-Zn has the highest μ and μ/ρ values whereas BSNS-Li has the lowest μ and μ/ρ values. The HVLs and TVLs of BSNZ-Zn are the smallest among the BSNZ-MO glasses. The Zeff values of BSNZ-MO glasses change in order of BSNZ-Li < BSNZ-Mg < BSNZ-Ca < BSNZ-Zn. The Neff values of BSNZ-MO glasses vary like Zeff values except for 0.4 MeV–3 MeV photon energies. The TMSPs are the lowest for BSNZ-Zn and they are the greatest for BSNZ-Li for protons, alpha particles and heavy carbon ion. The ℜ values of electron are the maximum for BSNZ-Mg and they are minimum for the BSNz-Zn. Besides, The FNRC of the BSNZ-Li has the greatest whereas the FNRC of the BSNZ-Mg has the lowest among the BSNZ-MO glasses.
Cette thèse s’inscrit dans les stratégies développées pour atteindre une performance mécanique et biologique dans des verres bioactifs, qui contribue à répondre aux exigences de l’industrie biomédicale et dernièrement de l’industrie pharmaceutique. Une partie des études a mis en évidence l’effet du traitement thermocinétique des microparticules du verre 45S5 Bioglass® sur la formation de la porosité globulaire dans les revêtements élaborés par projection plasma à pression atmosphérique (APS). La compréhension du comportement des particules de 45S5 Bioglass® dans le jet de plasma a permis d’identifier les changements de la composition chimique subis par la poudre projetée du fait de la volatilisation des espèces Na+ et P+, et d’établir des stratégies pour réduire les défauts structuraux dans les revêtements. Des revêtements de verre/zircone yttriée (YSZ) élaborés par co-projection APS et plasma de suspensions (SPS) ont été également étudiés. Leur structure consistait en des splats/lamelles de microparticules de verre 45S5 Bioglass® entourés par des nanoparticules de YSZ. La double approche consistant à réduire la porosité globulaire et à ajouter un renforcement de nanoparticules a amélioré la microdureté Vickers des revêtements à base du verre 45S5 Bioglass®. Par ailleurs, les nanoparticules de YSZ ont présenté un effet catalytique sur la formation d’apatite lors de l’exposition de ces revêtements à un fluide physiologique simulé (SBF). La formation de la porosité dans des particules de verre atomisées par projection flamme (FS) a fait l’objet de la deuxième partie de cette thèse. Cela a conduit à identifier les phénomènes intervenant dans les particules en vol et à établir les conditions d’atomisation appropriées. La formation de la porosité interconnectée dans les particules atomisées est limitée à la fois par la diminution excessive de leur viscosité en vol et par le flux de chaleur hétérogène dans les particules de morphologie irrégulière. La rétention de cette porosité dans les matériaux hautement amorphes ayant une volatilisation importante des espèces lors de l’atomisation est favorisée à l’aide d’un agent externe (AE ; p. ex. : CaCO3). L’AE limite l’énergie thermique échangée par les particules de verre en vol, telle que la viscosité peut également être contrôlée par le rapport massique verre/AE, en plus des conditions d’atomisation. Cet agent externe à la surface des particules de verre atomisées agit comme formateur de cratères tout en facilitant la conduction de l’énergie thermique vers le centre des particules atomisées si leur conductivité thermique (λp) est plus élevée. L’utilisation de particules poreuses sous forme d’architectures ayant une porosité hiérarchique (scaffolds) constitue la dernière partie des études de cette thèse. Les scaffolds ont présenté une inhibition bactérienne en libérant des molécules de Sulfate de Gentamicine (SG) stockées dans leur structure. L’effet inhibiteur des scaffolds est prolongé à ~ 72 et 120 heures respectivement pour les souches à Gram positif et à Gram négatif. Les cellules ostéoblastes ont mis en évidence une viabilité modérée au contact de ces scaffolds étant donné les changements de la composition chimique des particules de verre 43S2,5 en verre 51S9,0 (selon la nomenclature de L. Hench) lors de l’atomisation par projection flamme. La viabilité cellulaire diminue lors de l’augmentation de la teneur massique de nanoparticules de YSZ infiltrées dans les particules poreuses de verre 51S9,0, en raison de l’apoptose cellulaire causée par la lixiviation des ions Y+. Cependant, l’effet catalytique de YSZ dans la formation d’apatite favorise l’adhésion, la prolifération et la reproduction des cellules ostéoblastiques survivantes dans les scaffolds ayant 10% mas. de YSZ.
This reference text provides an in-depth knowledge of advanced materials like titanium, titanium alloys, cobalt-chromium alloys, stainless steel and composite materials for biomechanical application like joint replacements, bone plates, bone cement, artificial ligaments and tendons, dental implants for tooth fixation and hip implants.
It comprehensively covers advancements in materials including graphene reinforced magnesium metal matrix, magnesium and its alloys, 2D nanomaterials. The text discusses important topics including advanced materials for biomechanical applications, design and analysis of stainless steel 316L for femur bone fracture healing, design and manufacturing of prosthetic dental implants, biomechanical study of clavicular fracture, and biochemical analysis of cervical clinical stability.
The text will serve as a useful text for graduate students and academic researchers in areas including materials science, manufacturing engineering, mechanical engineering, and industrial engineering.
Following the general increase of population and industrial development, the management of resources through use of secondary source of raw materials, recycling and energy recovery from waste products are growing in importance. There are many challenges associated with each approach in which waste treatment and handling its by-products are among the most environmentally concerned matters. This chapter is divided into two main parts for two types of waste management: municipal solid waste management, and wastewater management. In the first part, management of municipal solid waste, incineration as a tool for energy recovery and its hazardous by-products fly ash and bottom ash are introduced. It has shown that vitrification of these ashes could open lots of potential for their utilization in various products such as cement and clinker substitution, or preparation of foam glass–ceramics as construction materials. In this chapter, a guide to successfully vitrify fly ash is also introduced and discussed. The second part of this chapter is dedicated to wastewater management, focusing on the potential use of rice-husk, an agricultural by-product to be utilized as an adsorbent for removal of heavy metals from wastewater. The final heavy-metal containing rice husk introduces new environmental concerns prior to landfill, and we have shown that vitrification has the potential to safely encapsulate this material and even give the opportunity to prepare foam glass–ceramics after its vitrification.
The invention of bioactive glasses has undoubtedly represented an important watershed in the history of biomedicine, innovatively revolutionizing the key concept of biomaterials. Although 50 years have passed since the first bioactive glass (45S5 Bioglass®), these materials still continue to inspire numerous generations of researchers all over the world, attracted by the promise of numerous possible fields of investigations given by the versatility of glass manufacturing and processing strategies. This allows obtaining final clinical products that are incredibly diverse in terms of chemical characteristics, shape and texture and, therefore, adaptable to different therapeutic needs. The possibility to tune textural properties and degradation rates, perform high-temperature sintering processes without or minimally altering the original properties of the glass, as well as the facile introduction of therapeutically active ions within the composition and the easy surface functionalization led, over year, to the development of multiple pruducts to be used in various clinical fields, including the regeneration of both hard and soft tissues, bacterial/viral infection treatments and development of antitumoral strategies. This chapter opens a wide window on the world of bioactive glasses, starting with the description of their peculiar chemical properties, discussed in relation to the most commonly used manufacturing processes to obtain glass monoliths or particles. Then, an overview on the most common applications of BG-based products will be provided, paying particular attention to porous scaffolds for bone tissue engineering, bioactive coatings, antibacterial glasses and surface functionalization. In conclusion, a comprehensive overview on clinical applications updated to the state of the art will be provided.
Ceramic is associated to clay because earliest ceramic articles were made from naturally occurring materials such as clay minerals. Clays and many of the same raw materials are still serve as the main constituents of traditional ceramics that in broad sense encompass heavy clay products, construction materials, whitewares, refractories, glasses, etc. The aim of this chapter is to provide the basic information about the key technological operations and advances in production of structural clay products, wall and floor tiles, vitreous china sanitaryware, stoneware, majolica pottery and porcelain that would be useful to understand the world of these materials.
Glass has been a versatile and fascinating material since the early stages of civilization. The aesthetic and functional properties of glasses are mainly dictated by the composition, which in most cases is a mixture of inorganic oxides and can be properly designed according to the end use. Glass–ceramics are polycrystalline materials produced by the controlled crystallization of certain parent glasses and contain one or more crystalline phases embedded in a residual amorphous matrix. The distinct chemical nature and microstructural features of these phases have led to various combinations of properties and applications in many industrial, medical and high-tech fields. This chapter introduces the reader into the “mystery of glass”, providing a picture of the structural theories, formation criteria and main processing methods for glass and glass–ceramic products with focus on a selected set of silicate materials..
For the first time, the sol-gel method was coupled with electrostatic spray deposition (ESD) to fabricate nanotextured bioactive glass (BG) coatings with a controlled microstructure in a one-pot-process. Three BG compositions belonging to the SiO2-CaO-P2O5 system (S85, S75, and S58) were homogeneously deposited on metallic Ti6Al4V substrates starting from the atomization of precursor solutions. All coatings displayed an amorphous character, as confirmed by XRD. A wide variety of innovative BG morphologies were obtained, tuning the key parameters of ESD, leading from highly porous coral-like to compact reticular-type coatings. The bioactivity, in terms of apatite formation, of as-deposited coatings was tested by immersion in simulated body fluid solution. Textural properties were found to play an important impact in its biological performance. Highly porous ESD-coatings exhibited remarkable bioactivity for S75 and S58 compositions, compared with more compacted ones of equal formulations. S85 composition was found extremely reactive regardless of the coating microstructure.
Free from toxic elements biomaterial potentially applicable for load bearing biomedical implants was obtained for the first time by laser cladding of S520 bioactive glass onto ultrafine-grained commercially pure titanium. The cladding process affected the refined structure of the substrate inducing martensitic transformation near its surface. The α’ acicular martensite gradually passes into relatively large grains with increasing distance from the substrate surface, which subsequently are transformed into smaller grains of about 2 μm in diameter. Both the melted zone, where the martensite crystalline structure was found, and the HAZ are characterised by relatively lower hardness in comparison with that of the substrate core indicating increased ductility. Such a combination of zones with different properties may have a synergistic effect and is beneficial for the obtained biomaterial. A characteristic region in the form of about 3 μm width band was formed in the melted zone at about 10 μm below the titanium surface. The results of EDS analysis indicate that several glass elements moved into the region while the titanium content in the same area was decreased. High bioactivity of the coated S520 glass was revealed by in vitro testing with SBF solution and almost complete reduction of P concentration occurred after 14 days.
Bioceramics have a great potential in ophthalmology and these materials were tested and applied in three different fields of ophthalmic surgery: oculoplastic surgery for orbital floor repair, orbital implants for anophthalmic patients and ocular keratoprosthesis (artificial cornea).
Currently, Hydroxyapatite (HA), Polyethylene (PA) and Alumina are the most used biomaterials for ocular surgery. In the case of orbital floor repair the implant acts as a bone graft providing structural support at the bone defect site (fracture). Porous bioceramics stimulate fibrovascular in-growth, which is a fundamental feature to stabilize the orbital implant in anophthalmic patients, and also secure an appropriate motility of ocular prosthesis. In the field of keratoprosthesis, bioceramics are mainly used to make a skirt that aims to connect the central optical part of the keratoprosthesis with the host tissue.
Recently, many others biomaterials, among them Bioactive glasses (BGs) and Bioactive glass-ceramics (BGCs), have been extensively investigated for applications in ocular surgery. The extraordinary versatility of these biomaterials, which primarily depends on the flexibility of their composition, allows various applications in ophthalmology. It has been suggested recently that BGs and BGCs possess a unique power of stimulating tissue regeneration and cell activity in vivo. BGs and BGCs can make better the performance of ocular implants. Bioactive glasses are a very promising in this field of orbital floor fractures and defect repairment because they are known to bond both to bone and muscle tissue which is the main property for implants used in reconstructive surgery. Furthermore, through the release of adequate ionic dissolution products, porous bioactive glasses can stimulate angiogenesis and fibrovascular in-growth, which are significant to ensure a suitable motility of orbital implants and lower the risk of infections. It was discovered that porous bioactive glasses are able to stimulate the keratocytes adhesion and proliferation, and that ability made them a material that is potentially desirable and a leading candidate for a new and improved kind of keratoprosthesis skirts.
Bioactive glasses can be used as devices for the controlled release of therapeutic ions and therapeutic biomolecules. Considering the future, bioactive glasses and glass-ceramics can improve the performance of ocular implants imparting them key extra-functionalities such as antibacterial features via the release of adequate metal ions, controlled drug release, to elicit an angiogenic and anti-inflammatory effect at the implant site.
Plasma-sprayed 45S5 bioactive glass coatings were manufactured using two types of powder feedstocks (commercial and lab-made 45S5 glass) and two plasma torches (single and triple cathode) to analyse their influence on the microstructure and bioactivity of the coatings. Besides, the volatilisation of glass oxides such as Na2O and P2O5 during the deposition was studied. All coatings were microstructurally characterised by scanning electron microscopy, X-ray diffraction and X-ray dispersive energy analysis. Moreover, the bioactivity of the sprayed coatings was studied by immersing the coatings in Simulated Body Fluid until 14 days.
The coatings obtained using the triple cathode torch showed similar thickness, less total porosity and greater microstructural homogeneity than the coating deposited with the single cathode torch. X-ray dispersive energy analysis revealed lower amounts of sodium and phosphorus at the surrounding of the lamellae, due to its volatilisation during the formation of the coatings. The volatilisation of these elements varied depending on the type of feedstock and plasma jet enthalpy. Concerning the bioactivity of the coatings, all of them have developed a hydroxycarbonate apatite layer on their surface.
Bioactive glasses have been used successfully as bone-filling materials in orthopaedic and dental surgery, but their poor mechanical strength limits their applications in load-bearing positions. Approaches to strengthen materials decrease their bioactivity. In order to realize the optimal matching between mechanical and biological properties, the sol-gel-self propagating method is adopted to prepare gel-derived bioglass bulk: 58S in the system SiO2–CaO–P2O5. The obtained glass was analysed for its composition, crystalinity and morphology through FT-IR, Raman, XRD, STEM and X-ray microanalysis.
Pulsed laser deposition (PLD) method was used to obtain bioglass (BG) thin film coatings on titanium substrates. An UV excimer laser KrF* (λ = 248 nm, τ = 25 ns) was used for the multi-pulse irradiation of the BG targets with 57 or 61 wt.% SiO2 content (and Na2O–K2O–CaO–MgO–P2O5 oxides). The depositions were performed in oxygen atmosphere at 13 Pa and for substrates temperature of 400 °C. The PLD films displayed typical BG of 2–5 μm particulates nucleated on the film surface or embedded in. The PLD films stoichiometry was found to be the same as the targets. XRD spectra have shown, the glass coatings obtained, had an amorphous structure. One set of samples, deposited in the same conditions, were dipped in simulated body fluids (SBFs) and subsequently extracted one by one after several time intervals 1, 3, 7, 14 and 21 days. After washing in deionized water and drying, the surface morphology of the samples and theirs composition were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), IR spectroscopy (FTIR) and energy dispersive X-ray analysis (EDX). After 3–7 days the Si content substantially decreases in the coatings and PO43− maxima start to increase in FTIR spectra. The XRD spectra also confirm this evolution. After 14–21 days the XRD peaks show a crystallized fraction of the carbonated hydroxyapatite (HAP). The SEM micrographs show also significant changes of the films surface morphology. The coalescence of the BG droplets can be seen. The dissolution and growth processes could be assigned to the ionic exchange between BG and SBFs.
The pulsed laser ablation deposition (PLAD) of a commercial Bioglass on Ti-6Al-4V alloy substrate was studied. PLAD provided the bioglass coating on titanium alloy substrate, the coating being of the same composition as that of the initial glass target. High quality glassy coating of 3.7 μm thickness was deposited at the laser beam fluence of about 9 J/cm2. The coating was subjected to the hydration resulting from the interaction with environment, as the bulk glass does too. The depth of the hydrated layer was about 3.0 μm, and the hardness of this layer increased from 0.5 till 3.8 GPa through the depth of the layer. Hardness of non-hydrated bioglass exceeded only slightly that of the substrate alloy.
The effect of silicon compounds on the formation and growth of natural bone tissue is examined, and the concentrations of
silicon compounds in different organ tissues are presented. The inductive action of different implantation substrates containing
silica on the vital activity of cultures of osteogenic cells is described. It is suggested that the process resulting in bonding
between bone tissue and silicate implantation material is affected by the presence of a substantial number of silanol groups
on the surface of the material, which determine its high hydrophilicity. It is shown that the solubility of silicate glasses
depends on the presence in them of a phase which corresponds to the composition of liquid glass, and its role in the biodegradation
of the materials in physiological media is described.
The fabrication of nanostructured coatings by means of thermal spray techniques is a challenging approach with new applications in mind. However, it requires the processing of very fine-grained powders with a grain size in the nanoscale. As nano- and submicrometer powders cannot be processed using mechanical powder feeders, new concepts have to be developed. Among these, suspension spraying is one of the most promising.High-velocity suspension flame spraying (HVSFS) is a new approach to spray micron, submicron or nanoparticles with hypersonic speed with the aim to form thin and dense coating layers. For this purpose, the powder is dispersed in aqueous or organic solvent and fed axially into the combustion chamber of a modified High-Velocity Oxyfuel (HVOF) spray torch. Several suspension feeder concepts were tested to ensure a constant flow of the suspension and, thus, a stable spray process.Different oxide materials were processed in form of a suspension containing submicrometer- or nanosized powders consisting of alumina, titania and yttrium stabilized zirconia (YSZ). The paper gives an introduction to HVSFS technology and will present first experimental results.
The field of biomaterials has become a vital area, as these materials can enhance the quality and longevity of human life and the science and technology associated with this field has now led to multi-million dollar business. The paper focuses its attention mainly on titanium-based alloys, even though there exists biomaterials made up of ceramics, polymers and composite materials. The paper discusses the biomechanical compatibility of many metallic materials and it brings out the overall superiority of Ti based alloys, even though it is costlier. As it is well known that a good biomaterial should possess the fundamental properties such as better mechanical and biological compatibility and enhanced wear and corrosion resistance in biological environment, the paper discusses the influence of alloy chemistry, thermomechanical processing and surface condition on these properties. In addition, this paper also discusses in detail the various surface modification techniques to achieve superior biocompatibility, higher wear and corrosion resistance. Overall, an attempt has been made to bring out the current scenario of Ti based materials for biomedical applications.
Alumina and zirconia, S. Hulbert bioactive glasses - materials science, L. Hench and O. Andersson bioactive glasses-materails science, L. Hench and O. Anderson applications, J. Wilson and R.P. Happonen A/W glass-ceramic - processing and properties, T. Kokubo A/W glass ceramic - clinical applications, T. Yamamuro bioactive glass-ceramics - ceravital, U. Gross et al machineable glass-ceramics, W. Holland and W. Vogel hydroxyapotite, R. LeGros and J. LeGros porous ceramics, R. Holmes and E. Schors resorbable calcium phosphates, C.P.A.T. Klein et al hydroxyapatite coatings, W. Lacefield bioactive glass coatings, L. Hench and O. Andersson pyrolytic carbon coatings, R.H. Dauskardt and R.O. Ritchie bioceramic composites, P. Ducheyne polyethylene-HA composites, W. Bonfield radiotherapy glasses, D. Day characterization of bioceramics, L. Hench regulation of medical devices, E. Horowitz and E. Mueller summary, L. Hench and J. Wilson appendices ASTM standards, J. Lemons and D. Greenspan.
Bioinert metallic implants such as titanium and titanium alloys could be coated with bioactive materials with good adhesion to metal and which could be also bonded to the bone. In order to predict the mechanical behavior of coatings during the implant insertion, mechanical properties of the surface and through the thickness of deposited bioglass coatings are necessary to be studied. We report an investigation of the mechanical characteristics of bioglass coatings using the nanoindentation and nanoscratch techniques. The coating topography with residual imprints was analyzed by in situ imaging method. The dependence of the friction coefficient on load in constant and ramped load tests as well as on the scratch speed is compared. Elastic modulus and hardness results after indentation on the coating surface with higher loads showed more consistent results with less pile up around imprints. The nanohardness and reduced elastic modulus of the coating is in the expected boundaries of theoretical values for glass and alloy with a moderate distribution through the coating thickness. Nanoscratch testing showed that the surface deform plastically with no visible debris or cracks.
Edited by major contributors to the field, this text summarizes current or newly emerging pulsed laser deposition application areas. It spans the field of optical devices, electronic materials, sensors and actuators, biomaterials, and organic polymers. Every scientist, technologist and development engineer who has a need to grow and pattern, to apply and use thin film materials will regard this book as a must-have resource.
Thermal spray is a continuous, directed, melt-spray process in which particles of virtually any material are melted and accelerated to high velocities, through either combustion flame of a dc or rf nontransferred thermal-plasma arc. The thermal spray technology, its materials science attributes, and some applications are reviewed. The automotive applications represent a major growth opportunity for thermal spray in the new millennium and are addressed in reasonable detail. New opportunities in the synthesis of functional multilayers and novel processing attributes are also reviewed.
A novel silicate based bioactive glass coating composition containing B2O3 and TiO2 having matching thermal properties with that of Ti6Al4V implants was developed and characterized. A conventional vitreous enamelling technique was used for coating small flat surface and curved surface of small rods. Hydroxyapatite (HAp) micro and nano-crystalline particles were used to prepare bioactive glass-HAp composite coating. Scratch testing was used to study the coating adhesion and its fracture behaviour under simulated conditions. As observed from scratch testing results, adhesion strength of the coating improved from 21N normal load to 27N and 32N on addition of micro-HAp and nano HAp powder, respectively, to bioactive glass matrix. Further, sterilization of the coated samples with 25kGy gamma irradiation substantially enhanced the adhesion of glass coating and HAp-composite coating.
In this paper a production technique is described for the application of glass coatings on diverse substrates, more particularly bioglass coatings on titanium. The glass is synthesized from base chemicals in a plasma torch and is applied as a coating in the same operation. In this way well-adhering coatings with controlled composition and amorphicity are obtained. Adhesion strengths above 40 MPa are easily obtained.
Bio-glass films were deposited by radio-frequency magnetron sputtering technique onto medical grade Ti6Al7Nb alloy substrates from prepared silica based bio-glass target. A low deposition temperature was used (150°C) and three different working pressures, followed by annealing in air at 550 and 750°C. A quasi-stoichiometric target to substrate atomic transfer was found for Si, Ca and P, along with strong enrichment in Na and depletion in K and Mg, as evidenced by the energy dispersive microanalysis. The best results, taking into account stoichiometry and surface roughness, were obtained for the BG layers deposited at 0.3Pa argon working pressure. The infrared spectroscopy of the as-sputtered and of the annealed films evidenced the characteristic molecular vibrations of silicate, phosphate and carbonate functional groups. The as-deposited films are amorphous and became partly crystalline after annealing at 750°C, as evidenced by X-ray diffraction. The pull-out measurements, performed with a certified pull-test machine, gave very strong film–substrate adhesion strength values. For the non-crystalline layers, the pull-out strength is higher than 85MPa, and decreases after annealing at 750°C to 72.9±7.1MPa. The main objective of this work was to establish the influence of the working pressure upon the composition and morphology of the as-deposited films, and of the annealing temperature upon structure and film–substrate adhesion.
We report the synthesis by pulsed laser deposition of thin structures of two bioactive glasses belonging to the SiO2–Na2O–K2O–CaO–MgO–P2O5 system, on medical grade Ti substrates. We evaluated their biocompatibility after immersion in simulated body fluids and by performing cells adhesion tests. The films were characterized by confocal scanning laser microscopy and Fourier transform infrared spectrometry, before and after 30 and 46 days immersion in fluids. Our studies demonstrated that deposited coatings were degraded in simulated fluids. A new apatite layer was synthesized by ions changing with the fluid during the decomposition of bioglasses. We investigated after immersion in fluids cells adhesion and the cytoskelet organization of synthesized structures, by fluorescence microscopy. A good adhesion to bioglass coatings was evidenced.
This review article, dedicated to Prof. Jacques Livage, is focused on current trends in bioceramics. The first generation of inert ceramics aimed to substitute natural bone, hence the research was only focused on inert materials; the second one was aimed at mimicking some biomineralization-related functions and sol-gel chemistry plays a paramount role in their synthesis and properties. Finally, the purpose with third generation bioceramics is basically to provide an adequate scaffolding system which helps the bone cells to perform their natural processes. Tissue engineering attempts to develop artificial materials able to replace biological tissues in situations where the human body cannot perform said replacement by itself. One attempt consists on designing biomimetic materials that combine synthetic materials with cellular recognizing positions. These ceramics must exhibit an adequate degree of porosity. All these ideas shall be discussed in the present work.
Bioactive materials such as hydroxyapatite (HA) are used as coatings on metallic implants, producing a conjugate with better performance. The coatings are in general obtained by a plasma spray process. In this work the structural properties of composite coatings hydroxyapatite/bioactive glass (HA/BG) as well as coatings of the pure materials are measured. The coatings were obtained by plasma spraying mixtures of the powders Bioglass® and HA, in different proportions. The process parameters, arc current and primary/secondary gas ratios, were also varied. X-ray diffraction (XRD), infrared spectroscopy and scanning electron microscopy (SEM) measurements were made of the coatings. The in vitro bioactivity of the different coatings was also evaluated. The results showed that Bioglass® addition to the coating powders increased the dissolution rates and rate of formation of a HA film on the surface of the coatings, thus increasing its in vitro bioactivity compared to pure HA coatings.
Five glasses in the CaO−SiO2 binary system with different silica content (50−90% in mol) have been prepared by the sol−gel method. The referred glasses have been characterized by thermogravimetric and differential thermal analysis (TG/DTA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) showing clear differences in composition and specific surface and porosity between those glasses with low SiO2 content (50−70% in mol) and those with high SiO2 content (80−90% in mol). The in vitro bioactivity study of all glasses prepared were carried out by soaking in a simulated body fluid (SBF) at 37 °C. The FTIR, XRD, SEM, and EDS analysis of the surface of these glasses after the in vitro assays reveal the formation of a hydroxycarbonate apatite (HCA) layer. The formation process of this layer on the glass is a function of the glass composition. The rate of formation increases in those glasses with lower SiO2 (50−70% in mol).
Dense and ultrafine alumina–zirconia composites (Al2O3–16wt%ZrO2 and ZrO2–20wt%Al2O3) are developed and characterized for load bearing prosthetic applications. The improvement of the ceramic/bone interface, namely of the ceramic bioactivity, is performed by a glass coating on the surface of the composites. A new composition is used to produce the glass powder, by melting at 1550°C the mixture of oxide raw materials. The processing to obtain a homogeneous and adherent coating on the ceramic substrates is investigated: the optimal temperature for the glazing treatment is 1200°C. The microstructure of the coating and of the ceramic/coating interface, the adhesion and some mechanical properties of the prepared glass and of the coating are analyzed. Besides, the in vitro bioactive responses, by incubation of osteoblast-like cells on the coated samples, are evaluated: positive results are confirmed after 24h and 72h.
Ceramics used for the repair and re- construction of diseased or damaged parts of the musculo-skeletal sys- tem, termed bioceramics, may be bio- inert (alumina, zirconia), resorbable (tricalcium phosphate), bioactive (hy- droxyapatite, bioactive glasses, and glass-ceramics), or porous for tissue ingrowth (hydroxyapatite-coated met- als, alumina). Applications include re- placements for hips, knees, teeth, tendons, and ligaments and repair for periodontal disease, maxillofacial re- construction, augmentation and stabi- lization of the jaw bone, spinal fusion, and bone fillers after tumor surgery. Carbon coatings are thromboresistant and are used for prosthetic heart valves. The mechanisms of tissue bonding to bioactive ceramics are be- ginning to be understood, which can result in the molecular design of bio- ceramics for interfacial bonding with hard and soft tissues. Composites are being developed with high toughness and elastic modulus match with bone. Therapeutic treatment of cancer has been achieved by localized delivery of radioactive isotopes via glass beads. Development of standard test methods for prediction of long-term (20-year)
Ceramics used for the repair and reconstruction of diseased or damaged parts of the musculo-skeletal system, termed bioceramics, may be bioinert (e.g., alumina and zirconia), resorbable (e.g., tricalcium phosphate), bioactive (e.g., hydroxyapatite, bioactive glasses, and glass-ceramics), or porous for tissue ingrowth (e.g., hydroxyapatite-coated metals). Applications include replacements for hips, knees, teeth, tendons, and ligaments and repair for periodontal disease, maxillofacial reconstruction, augmentation and stabilization of the jaw bone, spinal fusion, and bone repair after tumor surgery. Pyrolytic carbon coatings are thromboresistant and are used for prosthetic heart valves. The mechanisms of tissue bonding to bioactive ceramics have resulted in the molecular design of bioceramics for interfacial bonding with hard and soft tissue. Bioactive composites are being developed with high toughness and elastic modulus that match with bone. Therapeutic treatment of cancer has been achieved by localized delivery of radioactive isotopes via glass beads. Clinical success of bioceramics has led to a remarkable advance in the quality of life for millions of people.
We report on the synthesis by pulsed laser deposition with a KrF* excimer laser source (λ = 248 nm, τ = 25 ns) of bioglass thin films of 6P57 and 6P61 types. Physiology, viability, and proliferation of human osteoblast cells were determined by quantitative in vitro tests performed by flow cytometry on primary osteoblasts cultured on pulsed laser deposited bioglasses. Both types of glass films proved to be appropriate mediums for cell survival and proliferation. In a parallel investigation, cell morphology and adhesion to the surface was studied by fluorescence microscopy and scanning electron microscopy. Strong bonds between the materials and cells were found in both cases, as osteoblast pseudopodes penetrated deep into the material. According to our observations, the 6P57 glass films were superior with respect to viability and proliferation performances.
A study of the laser ablation and deposition, on Ti–Al substrates, of a biologically active glass (Bioglass®) suitable for bone implants is reported. The analysis of the gaseous phase by emission spectroscopy and the characterisation of the films from a compositional and morphological point of view have been carried out. The mean chemical composition of the deposits obtained from Bioglass ablation is very close to the target composition and the morphology indicates that different mechanisms of material ejection are present.
Conventional bioactive glasses, in bulk form, are being considered as biomaterials in prosthetic applications. In this study, a new attempt was made to coat bioactive glasses on Ti-6A1-4V by plasma spraying. This method will coat the bioactive glass coatings (BGCs) onto metal substrate, potentially combining the excellent mechanical strength of metal and biocompatibility of bioactive glass. Analysis by X-ray diffractometry (XRD) of the BGCs, revealed that the amorphous structure of glass was preserved. BGCs were soaked in simulated body fluid (SBF) to evaluate their properties in vitro. After soaking in SBF for 1 day, precipitation of fiber structure was observed on the surface of the BGCs. After 2 and more days, the surface of the BGCs was completely covered with precipitates. The precipitates, identified as the apatite phase by XRD, contained carbonate and hydroxyl functional groups detected by Fourier transform IR reflection (FTIR) spectroscopy. After soaking for 16 days, a thin layer of about 10 μm, rich in calcium and phosphorus but poor in silicon, was observed on the surface of the BGCs. The composition of the CaP rich layer was consistent with the apatite structure identified by various methods, but the apatite layer was significantly thicker than reported in bulk form. The formation of an apatite phase surface has been suggested to be indicative of biocompatibility. All findings in this study indicated the formation of apatite on the surface of plasma-sprayed BGCs, and this material is expected to be biocompatible in vivo.
Laser surface cladding has become an extensively used technique in metallurgical applications in order to improve surface properties of materials. We have proposed this technique in the field of biomaterials to coat the surface of titanium alloy substrates used in orthopaedical implants with a calcium phosphate (CaP) bioceramic to promote the growth of the bone when the implant is inserted in the body.An exhaustive study on the influence of the processing parameters on finished surface, microstructure and superficial composition was carried out. Also, the geometrical features of the CaP coatings were correlated to the relevant processing parameters. Simple linear relationships between the studied clad features and processing parameters have been found.Different techniques applied to characterise the coated samples revealed the gradual composition of the coatings starting with a biphasic calcium phosphate on the surface and ending with a compound between the calcium phosphate and the metallic substrate in the coating–substrate interface.
Biocorrosion behavior and changes in morphology and phases of hydroxyapatite (HA), bioactive glass (BG) and HA/BG coatings in Hank's physiological solution is investigated. Results showed that as-coated BG had the roughest surface, while as-coated HA had the smoothest surface. The HA/BG coating was comprised of both bubble-shaped particles of BG and small irregular-shaped particles of HA. Low intensity X-ray diffraction (XRD) peaks of CaO, β-TCP and Ca4P2O5, besides the major apatite peaks, were observed in HA and HA/ BG coatings. BG coating had an essentially amorphous structure. When HA and HA/BG were immersed in Hank's solution for 30 days, most of the minor phases dissolved. When BG coating was immersed, both apatite and SiO2 peaks gradually rose. A sudden drop and recovery in OCP occurred to BG and HA/BG but not to HA. Anodic polarization showed that passivation and film breakdown occurred to all three coatings. Passivation started approximately from 200, 300 and 400 mV(SCE) for HA, HA/BG and BG coatings, respectively. The three coatings had similar critical current densities. The released calcium ion concentration was found the highest in HA-tested solution, while the concentrations of sodium and silicon were the highest in BG-tested solution. The drop-and-rise phenomenon was also observed in the FT-IR spectra of immersed HA and HA/BG coating. These FT-IR results are consistent with the XRD results reported earlier.
Effects of the Ar pressure on the morphology, structure, bonding configuration and deposition rate of the bioglass thin films were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and crystal lattice monitor. Ar pressure has an influence on the quantity and shapes of the particles generated in the PLD process. The target bonding configuration is not correctly transferred to the films. This effect is attributed to the network rearrangement during the film growth, which is associated to special structure of glass and complex physical mechanisms of PLD. Deposition rate decreases as the pressure increases following a linear dependence.
Effects of the substrate temperature on the bonding configuration and adhesion strength of the bioglass films deposited by pulsed laser were investigated by Fourier transform infrared spectroscopy (FTIR) and scratch apparatus. Morphology of the films is compact with the particles on the surface of them and the structure is amorphous glass. Bonding configuration is different from that of the target. Si–O–NBO/Si–O–Si (s) intensity ratios of the films decline as compared with the target. Besides, this tendency is obvious as the substrate temperature decreases. This effect is attributed to the network rearrangement during the film growth, which is associated to special structure of glass and complex physical mechanisms of pulsed laser deposition (PLD). Scratch test results show that the film deposited at 200 °C has the highest adhesion strength.
Silicon-substituted hydroxyapatite (Si-HA) coatings with 0.14 to 1.14 at.% Si on pure titanium were prepared by a biomimetic process. The microstructure characterization and the cell compatibility of the Si-HA coatings were studied in comparison with that of hydroxyapatite (HA) coating prepared in the same way. The prepared Si-HA coatings and HA coating were only partially crystallized or in nano-scaled crystals. The introduction of Si element in HA significantly reduced P and Ca content, but densified the coating. The atom ratio of Ca to (P + Si) in the Si-HA coatings was in a range of 1.61–1.73, increasing slightly with an increase in the Si content. FTIR results displayed that Si entered HA in a form of SiO4 unit by substituting for PO4 unit. The cell attachment test showed that the HA and Si-HA coatings exhibited better cell response than the uncoated titanium, but no difference was observed in the cell response between the HA coating and the Si-HA coatings. Both the HA coating and the Si-HA coatings demonstrated a significantly higher cell growth rate than the uncoated pure titanium (p < 0.05) in all incubation periods while the Si-HA coating exhibited a significantly higher cell growth rate than the HA coating (p < 0.05). Si-HA with 0.42 at.% Si presented the best cell biocompatibility in all of the incubation periods. It was suggested that the synthesis mode of HA and Si-HA coatings in a simulated body environment in the biomimetic process contribute significantly to good cell biocompatibility.
artículo forma parte del "Volumen Suplemento" S1 de la Revista Latinoamericana de Metalurgia y Materiales (RLMM). Los suplementos de la RLMM son números especiales de la revista dedicados a publicar memorias de congresos. Este suplemento constituye las memorias del congreso "X Iberoamericano de Metalurgia y Materiales (X IBEROMET)" celebrado en Cartagena, Colombia, del 13 al 17 de Octubre de 2008. La selección y arbitraje de los trabajos que aparecen en este suplemento fue responsabilidad del Comité Organizador del X IBEROMET, quien nombró una comisión ad-hoc para este fin (véase editorial de este suplemento). La RLMM no sometió estos artículos al proceso regular de arbitraje que utiliza la revista para los números regulares de la misma. Se recomendó el uso de las "Instrucciones para Autores" establecidas por la RLMM para la elaboración de los artículos. No obstante, la revisión principal del formato de los artículos que aparecen en este suplemento fue responsabilidad del Comité Organizador del X IBEROMET.
Alumina was coated with bioactive glass which is known to show a bonding behavior to living tissue. Another glass also coated between alumina and bioactive glass to compensate their differences in thermal expansion. After coating the alumina with bioactive glass, it reacted in simulated body fluids to investigate the formation of hydroxyapatite. The bioactive-glazed layer crystallized into a-wollastonite and b-wollastonite crystalline phases when the glaze was fired at 1200 C and 1100 C, respectively. When the sam-ples reacted in SBF, a-wollastonite easily leached out of the surface and hydroxyapatite formed on the leached site. The leaching rate of a-wollastonite was faster than that of b-wollastonite, and the hydroxyapatite-forming rate was also faster in the sample containing a-wollastonite than in the other sample. No silica-rich layer was found underneath the newly developed hydroxyapatite.
Formation of a high-strength bioactive glass-ceramic in the system MgO-CaO-SiO2-P2O5 was investigated by observing the microstructure of the crystallized products. Crystallization of the parent glass in a bulk form led to the occurrence of large cracks in the crystallized product. This was attributed to the precipitation of fibrous-wollastonite crystals growing perpendicular to the outer surfaces of the glass after uniform precipitation of fine oxyapatite/fluoroapatite crystals. On the other hand, crystallization of the same glass in a powder compact led to the formation of a crack-free dense crystallized product due to uniform precipitation of both apatite and wollastonite fine crystals throughout the glass article. The uniform precipitation of the wollastonite crystals was attributed to the simultaneous formation of fine crystals in the individual glass particles.
The aim of this work has been the preparation and evaluation of sol-gel coatings for clinical applications. Research was focussed in the development of highly corrosion resistant and/or bioactive sol-gel coatings onto AISI 316L stainless steel. Hybrid SiO2 sol-gel coatings inhibited corrosion and Fe diffusion, although no signal of bioactivity was detected. The inclusion of Ca- and P-alcoxides in the sol composition did not promote bioactivity. Bioactive coatings were obtained from suspensions prepared by adding glass (CaOSiO2P2O5) particles to an hybrid organic-inorganic SiO2 sol. The dissolution of glass particles promoted in vitro induction of apatite along with a slight reduction in the corrosion resistance of coated pieces. By combining an inner SiO2 hybrid film acting as barrier against corrosion with an outer coating containing bioactive glass particles, a significant improvement in the electrochemical behaviour was observed. This double-layered coating showed in vitro signals of bioactivity, and preliminary in vivo tests gave promising results.
Polyetheretherketone (PEEK) and PEEK/Bioglass® coatings were produced on shape memory alloy (NiTi, Nitinol®) wires using electrophoretic deposition (EPD). Best results were achieved with suspensions of PEEK powders in ethanol in the range (1–6wt%), using a deposition time of 5minutes and applied voltage of 20Volts. EPD using these parameters led to high quality PEEK coatings with a homogeneous microstructure along the wire length and a uniform thickness of up to 15μm without development of cracks or the presence of large voids. Suspensions of PEEK powders in ethanol with addition of Bioglass® particles (0.5–2wt%) (size<5μm) were used to produce PEEK/Bioglass® coatings. Sintering was carried out as a post EPD process in order to densify the coatings and to improve the adhesion of the coatings to the substrate. The sintering temperature was 340°C, sintering time 20min and heating rate 300°C/h. Sintering led to uniform and dense PEEK and PEEK/Bioglass® coatings without any cracks. The bioactive behaviour of PEEK/Bioglass® composite coatings was investigated by immersion in acellular simulated body fluid (SBF) for up to two weeks. As expected, hydroxyapatite crystals formed on the surface of the coated wires after 1week in SBF, confirming the bioactive character of the coatings. The results have demonstrated for the first time that EPD is a very convenient method to obtain homogeneous and uniform bioactive PEEK and PEEK/Bioglass® coatings on Nitinol® wires for biomedical applications.
A graded glass coating for Vitallium®, a Co-Cr alloy, has been prepared using a simple enameling technique. The composition
of the glasses has been tailored to match the thermal expansion of the alloys. The optimum glass composition and firing conditions
(temperature and time) needed to fabricate homogeneous coatings with good adhesion to the alloy were determined. The final
coating thickness ranged between 25 and 60 μm. Coatings fired under optimum conditions do not delaminate during indentation
tests of adhesion. Excellent adhesion to the alloy has been achieved through the formation of 100 nm thick interfacial chromium-oxide
(CrOx) layers. The graded glass (consisting of BIG and 6P50 layers) can be successfully coated to a Co-Cr alloy, and forms
hydroxyapatite (HA) on the coating surface when immersed in a simulated body fluid (SBF) for 30 days.
Scaffolds containing dual porosity at the nano and macroscale appear to exhibit improved performance in terms of crystallization
of hydroxycarbonate apatite plus cell adhesion and proliferation, as well as vascularization. The aim of the present work
is to develop a novel, simple sol–gel process for the preparation of silica-based bioactive porous bone tissue scaffold, with
a pore structure consisting of interconnected pores of both 100’s of micrometers and 10’s of nanometers in size, optimized
for enhanced bone regeneration performance. SiO2–CaO and SiO2–CaO–P2O5 porous glass monoliths have been prepared with a dual pore structure including pores of both ~50–200 micrometers and a few
to 10’s of nanometers in size, based on polymerization-induced phase separation together with the sol-gel transition, by adding
a water soluble polymer to the precursor sol. The nanopore (~5–40nm) structure of such macroporous gel skeletons was tailored
by solvent exchange, followed by heat treatment at 600–700°C. The overall pore structure has been studied by Scanning Electron
Microscopy (SEM), N2-adsorption (BET), Mercury intrusion porosimetry and Infrared spectroscopy. The scaffold bioactivity, tested in simulated
body fluid, has been demonstrated by means of DRIFTS, SEM and X-ray diffraction measurements.
KeywordsBioactive glass–Scaffold–Sol–gel–Dual porosity–SEM–BET–Mercury intrusion porosimetry
Titanium and its alloys are widely used as materials for implants, owing to their corrosion resistance, mechanical properties and excellent biocompatibility. However, clinical experience has shown that they are susceptible to localised corrosion in the human body causing the release of metal ions into the tissues surrounding the implants. Several incidences of clinical failures of such devices have demanded the application of biocompatible and corrosion resistant coatings and surface modification of the alloys. Coating metallic implants with bioactive materials is necessary to establish good interfacial bonds between the metal substrate and the bone. Hence, this work aimed at developing a bioglass-apatite (BG-HAP) graded coating on Ti6Al4V titanium alloy through electrophoretic deposition (EPD) technique. The coatings were characterized for their properties such as structural, electrochemical and mechanical stability. The electrochemical corrosion parameters such as corrosion potential (Ecorr) (open circuit potential) and corrosion current density (Icorr) evaluated in simulated body fluid (SBF) have shown significant shifts towards noble direction for the graded bioglass-apatite coated specimens in comparison with uncoated Ti6Al4V alloy. Electrochemical impedance spectroscopic investigations revealed higher polarisation resistance and lower capacitance values for the coated specimens, evidencing the stable nature of the formed coatings. The results obtained in the present work demonstrate the suitability of the electrophoretic technique for the preparation of graded coating on Ti6Al4V substrates.
Preparation and characterization of bioactive glass nanopowder and development of bioglass coating for biocompatibility improvement of 316L stainless steel (SS) implant was the aim of this work. Bioactive glass nanopowder was made by sol–gel technique and transmission electron microscopy (TEM) technique was utilized to evaluate the powders shape and size. The prepared bioactive glass nanopowder was immersed in the simulated body fluid (SBF) solution at 37 °C for 30 days. Fourier transform infrared spectroscopy (FTIR) was utilized to recognize and confirm the formation of apatite layer on the prepared bioactive glass nanopowder. Bioactive glass coating was performed on SS substrate by sol–gel technique. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) techniques were used to investigate the microstructure and morphology of the coating. Electrochemical polarization tests were performed in physiological solutions at 37 °C in order to determine and compare the corrosion behavior of the coated and uncoated SS specimens. Cyclic polarization tests were performed in order to compare the pitting corrosion resistance of the coated and uncoated SS specimens. The results showed that the size of bioactive glass powder was less than 100 nm. The formation of apatite layer confirmed the bioactivity of bioglass nanopowder. Bioactive glass coating could improve the corrosion resistance of 316L SS substrate. Bioactive glass coated 316L SS showed more pitting corrosion resistance in compare with pristine samples. It was concluded that by using the bioactive glass coated 316L SS as a human body implant, improvement of corrosion resistance as an indication of biocompatibility and bone bonding could be obtained simultaneously.
The aim of this work was preparation, development and characterization of bioactive glass coating by sol–gel technique for improvement of biocompatibility of 316L stainless steel implant used in dentistry and orthopaedic surgery.Bioglass powder was made by sol–gel technique and thermal properties of the prepared powder were studied using differential thermal analysis (DTA). The prepared bioglass powder was immersed in the simulated body fluid (SBF) solution. Fourier transform infrared spectroscopy (FTIR) was utilized to recognize and confirm of the formation of apatite layer on prepared bioglass powder. Bioactive bioglass coating was performed on 316L stainless steel (SS) substrate by the sol–gel technique. Structural characterization techniques including XRD, SEM and EDX were used to investigate the microstructure and morphology of the coating. Electrochemical potentiodynamic polarization tests were performed in two different types of physiological solutions at 37 °C in order to determine and compare the corrosion behavior of the bioglass coated SS and uncoated specimens as an indication of biocompatibility.The formation of apatite layer confirmed the bioactivity of the bioglass powder and tests revealed that all the films signs of bioactivity. It was also found that at sintering temperatures above 900 °C, crystalline phase Ca2SiO4 was formed. Crack-free and homogeneous bioglass coatings were obtained with no observable defects. The bioglass coating also improved corrosion resistance of the 316L SS substrates such as the corrosion current density of coated samples in comparison with pristine samples was decreased.It was concluded that the sol–gel bioglass coating can improve the corrosion behavior of dental and orthopedic metallic implants and two goals including improvement of biocompatibility and bone osteointegration can be obtained simultaneously.
There have been a number of major advances made in the field of bioactive ceramics, glasses and glass ceramics during the past 30–40 years. From initial work on the development of materials that are tolerated in the physiological environment, emphasis has now shifted towards the use of ceramic materials that interact with bone tissue by forming a direct bond. It is now possible to choose, by compositional control, whether these materials are biologically stable once incorporated within the skeletal structure or whether they are resorbed over time. This paper reviews the ground-breaking work that was performed during the 1970s and 1980s in the field of bioceramics in the production and characterisation of bioactive and bioresorbable glasses, glass ceramics and calcium phosphates. The review then explores the influence of the original concepts and ideas on the more recent development of ceramic scaffolds, composites and coatings with enhanced bioactivity for bone tissue engineering.
Three different bioactive glass-matrix composites were obtained by a viscous flow sintering process: the green samples were prepared by uniaxial cold pressing of powdered glasses (labelled as AP40, TAP and RKKP in this paper), mixed with 15% (volume) of titanium particles. The viscous flow sintering process was optimised by thermal analysis (DTA) and by heating microscopy to obtain high density bulk composites. The glasses and the sintered composites were also powdered and deposited by Vacuum Plasma Spray (VPS) on a Ti-6Al-4V alloy, to obtain bioactive glass and composite coatings. Each coating was characterised by means of optical and electron microscopy, X-ray diffraction (XRD), energy dispersion spectroscopy (EDS), Vickers indentations and shear tests. The bioactivity of the coatings was tested by soaking the coated samples into a simulated body fluid (SBF) at 37°C: the growth of a Ca and P rich silica-gel layer was observed on their surface after 30 days. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analyses were performed on the SBF in order to observe the Si, Ca and P leaching versus the time. Each coating showed a good adherence to the metallic substrate, comparable with that of the VPS hydroxyapatite coatings and a remarkable bioactivity. Moreover the intrinsic toughness of the composite coatings was found to be higher than that of the pure glass coatings.
The paper reports the first attempt at employing the innovative high-velocity suspension flame spraying (HVSFS) technique in order to deposit bioactive glass coatings. Fine (micrometric) glass particles having a composition similar to that of the A–W (apatite–wollastonite) bioactive glass–ceramic as proposed by Kokubo were dispersed into a 50% water + 50% isopropanol solvent mixture and the resulting suspension (containing 20 wt.% glass powder) was thermally sprayed onto Ti plates using a modified high velocity oxy-fuel torch.Each torch pass produces a dense coating layer, featuring strong cohesion between lamellae thanks to viscous flow sintering along the interlamellar boundary. However, some porosity exists between different layers deposited during successive torch passes.In vitro bioactivity tests indicate that the coatings interact remarkably with the simulated body fluid (SBF), developing a thick silica-rich layer containing hydroxyapatite crystals.
Bioactive glass (BG), calcium hydroxyapatite (HA), and ZrO2 doped HA thin films were grown by pulsed laser deposition on Ti substrates. An UV KrF* (λ = 248 nm, τ ≥ 7 ns) excimer laser was used for the multi-pulse irradiation of the targets. The substrates were kept at room temperature or heated during the film deposition at values within the (400–550 °C) range. The depositions were performed in oxygen and water vapor atmospheres, at pressure values in the range (5–40 Pa). The HA coatings were heat post-treated for 6 h in a flux of hot water vapors at the same temperature as applied during deposition. The surface morphology, chemical composition, and crystalline quality of the obtained thin films were studied by scanning electron microscopy, atomic force microscopy, and X-ray diffractometry. The films were seeded for in vitro tests with Hek293 (human embryonic kidney) cells that revealed a good adherence on the deposited layers. Biocompatibility tests showed that cell growth was better on HA than on BG thin films.
Three bio-phosphate glass-specimens with and without Al2O3 addition were prepared in order to shed light on their bioactivity behavior towards the simulated body fluid biological solution (SBF). The results revealed that Al2O3 has significant effect on the ability of bio-glass to form the hydroxycarbonate apatite layer on its surface. That layer was detected by FTIR spectra, SEM micrographs and EDAX pattern. Also, the effect of Al2O3 on the mechanical properties was studied by measuring the hardness of the glass samples, which increased by Al2O3 addition. The thermal expansion coefficient was decreased by increasing the Al2O3 percent in the bio-glass samples.
Electrophoretic deposition (EPD) is attracting increasing interest as a materials processing technique for a wide range of technical applications. This technique enables the production of unique microstructures and nanostructures as well as novel and complex material combinations in a variety of macroscopic shapes, dimensions and arrangements starting from micron-sized or nanosized particles. This review presents a comprehensive summary of relevant recent work on EPD describing the application of the technique in the processing of several traditional and advanced materials (functional and structural ceramic coatings, composite and porous materials, laminated ceramics, functionally graded materials, thin films and nanostructured materials), with the intention to highlight how EPD evolved from being a technique restricted only to traditional ceramics to become an important tool in advanced materials processing and nanotechnology. Moreover the fundamental EPD mechanisms and novel theories proposed to clarify the processes involved are explained.
The in vitro behaviour of bioactive glass coatings grown by Pulsed Laser Deposition on silicon and titanium substrates is presented. The critical thickness of the coatings needed to develop the complete bioactive reactions when immersed in Simulated Body Fluid was evaluated. The influence of the substrate on the reactivity of thin coatings, which lead to the production of calcium phosphate and silica-rich layers, is discussed. Furthermore, the temporal evolution of the bioactivity process was followed for thick bioactive glass coatings deposited on biomorphic silicon carbide ceramics. In the in vitro tests of coated porous materials, the surface area to volume of Simulated Body Fluid ratio was revealed as a key parameter. The effective surface area should be carefully estimated in order to avoid adverse effects on the bioactive process.
Sol–gel bioglasses have many advantages comparing to melt-derived bioglasses. 3-D scaffold prepared by sol–gel method is a promising substrate material for bone tissue engineering. But, it is difficult to produce macroporous sol–gel bioglasses with pores larger than 100 μm. In this work, a series of macroporous bioglasses was produced by adding PEG particles into the sol as pore former. The mesoporous texture features of the samples were assessed through a nitrogen sorption technique. The macropore structure was collected by intrusion mercury porosimetry. In vitro tests showed that the samples had good bioactivity. Combining the sol–gel routine with the pore former might be a useful approach for preparation scaffolds with applications to the repair and reconstruction of damaged tissue.