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The surface reactivity of different sets of glasses and glass-ceramics belonging to the SiO(2)-P(2)O(5)-CaO-MgO-K(2)O-Na(2)O system have been investigated. The attention was focused on the role of their composition on the bioactivity kinetics, in terms of pH modifications, silica-gel formation and its evolution toward hydroxycarbonatoapatite, after different times of soaking in simulated body fluid. Glasses and glass ceramics have been characterized by thermal analysis, SEM-EDS observations and phase analysis (XRD). XPS measurements have been carried out on the most representative set of sample in order to evaluate the evolution of the surface species during the growth of silica-gel and hydroxycarbonatoapatite. The response of murine fibroblast 3T3 to the material before and after a conditioning pre-treatment (immersion in SBF) has been investigated on the same set of samples in order to point out the role of the bioactivity mechanism on cell viability. The main differences among the various glasses have been related to the modifier oxides ratio and to the MgO content, which seems to have an influence on the glass stability, both in terms of thermal properties and surface reactivity. The surface characterization and in vitro tests revealed few variations in the reactivity of the different glasses and glass-ceramics in their pristine form. On the contrary, the different surface properties before and after the pre-treatment in SBF seem to play a role on the biocompatibility of both glass and glass-ceramics, due to the different ion release and hydrophilicity of the surfaces, affecting both cell viability and protein adsorption.

The aim of this study was the preparation and characterization of bioactive glass–ceramic scaffolds for bone tissue engineering. For this purpose, a glass belonging to the system SiO2–P2O5–CaO–MgO–Na2O–K2O (CEL2) was used. The sponge-replication method was adopted to prepare the scaffolds; specifically, a polymeric skeleton was impregnated with a slurry containing CEL2 powder, polyvinyl alcohol (PVA) as a binding agent and distilled water. The impregnated sponge was then thermally treated to remove the polymeric phase and to sinter the inorganic one. The obtained scaffolds possessed an open and interconnected porosity, analogous to cancellous bone texture, and with a mechanical strength above 2 MPa. Moreover, the scaffolds underwent partial bioresorption due to ion-leaching phenomena. This feature was investigated by X-ray computed microcomputed tomography (micro-CT). Micro-CT is a three-dimensional (3-D) radiographic imaging technique, able to achieve a spatial resolution close to 1 μm3. The use of synchrotron radiation allows the selected photon energy to be tuned to optimize the contrast among the different phases in the investigated samples. The 3-D scaffolds were soaked in a simulated body fluid (SBF) to study the formation of hydroxyapatite microcrystals on the scaffold struts and on the internal pore walls. The 3-D scaffolds were also soaked in a buffer solution (Tris–HCl) for different times to assess the scaffold bioresorption according to the ISO standard. A gradual resorption of the pores walls was observed during the soakings both in SBF and in Tris–HCl.

This study aimed to fabricate and investigate the structure, mechanical properties and bioactivity of three-dimensional (3-D) glass–ceramic scaffolds for bone tissue engineering. The scaffold material was a fluoroapatite-containing glass–ceramic synthesized by a melting–quenching route. Glass–ceramic powders were mixed with polyethylene particles acting as pore formers; the blend was pressed to obtain “green” compacts that were thermally treated to remove the organic phase and to sinter the inorganic one. The structure and morphology of the resulting scaffolds were characterized by X-ray diffraction, scanning electron microscopy, density measurements and capillarity tests. Crushing tests were carried out to investigate the mechanical properties of the scaffolds. The in vitro bioactivity was assessed by soaking the scaffolds in simulated body fluid for different time frames and by analyzing the modifications that occurred on the sample surface. The scaffolds had an interconnected macroporous structure with pores up to 50% vol. and they showed an orthotropic mechanical behaviour and strength well above 20 MPa. In addition, in vitro tests put into evidence the excellent bioactivity of the material. Therefore, the prepared scaffolds can be used in bone reconstructive surgery as effective load-bearing grafts thanks to their ease of tailoring, bioactive properties and high mechanical strength.

A 57% SiO(2), 3% Al(2)O(3), 34% CaO and 6% Na(2)O glass (SCNA) has been produced in form of powders and deposited by plasma spray on titanium alloy and stainless steel substrates. The obtained coatings have been subjected to a patented ion-exchange treatment to introduce silver ions in the surface inducing an antibacterial behavior. Silver surface-enriched samples have been characterized by means of X-ray diffraction, SEM observation, EDS analysis, in vitro bioactivity tests, leaching tests by GFAAS (graphite furnace atomic adsorption spectroscopy) analyses, cells adhesion and proliferation, and antibacterial tests using Staphylococcus Aureus strain. In vitro tests results showed that the modified samples acquired an antimicrobial action against tested bacteria maintaining unaffected the biocompatibility of the glass. Furthermore the ion-exchange treatment can be successfully applied to glass-coated samples without affecting the properties of the coatings; the simplicity and reproducibility of the method make it suitable for glass or glass-ceramic coatings of different composition in order to produce coated devices for bone healing and/or prostheses, able to reduce bacterial colonization and infections risks.

Glass-ceramic macroporous scaffolds were prepared using glass powders and polyethylene (PE) particles of two different sizes. The starting glass, named as Fa-GC, belongs to the system SiO(2)-P(2)O(5)-CaO-MgO-Na(2)O-K(2)O-CaF(2) and was synthesized by a traditional melting-quenching route. The glass was ground and sieved to obtain powders of specific size which were mixed with PE particles and then uniaxially pressed in order to obtain crack-free green samples. The compact of powders underwent a thermal treatment to remove the organic phase and to sinter the Fa-GC powders. Fa-GC scaffolds were characterized by means of X-Ray Diffraction, morphological observations, density measurements, image analysis, mechanical tests and in vitro tests. Composite systems were then prepared combining the drug uptake-delivery properties of MCM-41 silica micro/nanospheres with the Fa-GC scaffold. The system was prepared by soaking the scaffold into the MCM-41 synthesis batch. The composite scaffolds were characterized by means of X-Ray Diffraction, morphological observations, mechanical tests and in vitro tests. Ibuprofen was used as model drug for the uptake and delivery analysis of the composite system. In comparison with the MCM-41-free scaffold, both the adsorption capacity and the drug delivery behaviour were deeply affected by the presence of MCM-41 spheres inside the scaffold.

This research work is focused on the preparation of macroporous glass-ceramic scaffolds with high mechanical strength, equivalent with cancellous bone. The scaffolds were prepared using an open-cells polyurethane sponge as a template and glass powders belonging to the system SiO(2)-P(2)O(5)-CaO-MgO-Na(2)O-K(2)O. The glass, named as CEL2, was synthesized by a conventional melting-quenching route, ground and sieved to obtain powders of specific size. A slurry of CEL2 powders, polyvinyl alcohol (PVA) as a binder and water was prepared in order to coat, by a process of impregnation, the polymeric template. A thermal treatment was then used to remove the sponge and to sinter the glass powders, in order to obtain a replica of the template structure. The scaffolds were characterized by means of X-ray diffraction analysis, morphological observations, density measurements, volumetric shrinkage, image analysis, capillarity tests, mechanical tests and in vitro bioactivity evaluation.

Bioactive glass-ceramic powders belonging to the following system SiO 2 -Na 2 O-CaO-MgO were prepared via sol-gel. These powders were compacted by cold uniaxial pressing and then sintered at low temperatures in order to obtain a porous consolidated system. The biomaterials were then soaked in a simulated body fluid (SBF) to study their bioactivity. Both the as obtained samples and the soaked ones, were characterized by means of X-ray diffraction and optical and scanning electron microscopy with energy dispersive spectroscopy (EDS). In this paper, we present some preliminary results on these glass-ceramics that we believe might be successfully proposed as scaffold for bone substitutes. Future developments will involve the addition to the glass-ceramic powders of a second organic phases thermally degradable in order to obtain a macroporous structure.

A new bioactive glass composition (CEL2) in the SiO(2)-P(2)O(5)-CaO-MgO-K(2)O-Na(2)O system was tailored to control pH variations due to ion leaching phenomena when the glass is in contact with physiological fluids. CEL2 was prepared by a traditional melting-quenching process obtaining slices that were heat-treated to obtain a glass-ceramic material (CEL2GC) that was characterized thorough SEM analysis. Pre-treatment of CEL2GC with SBF was found to enhance its biocompatibility, as assessed by in vitro tests. CEL2 powder was then used to synthesize macroporous glass-ceramic scaffolds. To this end, CEL2 powders were mixed with polyethylene particles within the 300-600 microm size-range and then pressed to obtain crack-free compacted powders (green). This was heat-treated to remove the organic phase and to sinter the inorganic phase, leaving a porous structure. The biomaterial thus obtained was characterized by X-ray diffraction, SEM equipped with EDS, density measurement, image analysis, mechanical testing and in vitro evaluation, and found to be a glass-ceramic macroporous scaffold with uniformly distributed and highly interconnected porosity. The extent and size-range of the porosity can be tailored by varying the amount and size of the polyethylene particles.

Glass-ceramic scaffolds for bone grafting have been prepared using the sponge replication method and a highly bioactive silica based glass belonging to the system SiO2-P2O5- CaO-MgO-Na2O-K2O (CEL2). The parameters for the sponge impregnation were optimized in order to obtain a continuous coating of the polymeric skeleton which will lead, after the polymeric phase removal, to a resistant macroporous glass-ceramic template. A complete characterization was carried out on the obtained scaffold in order to assess its morphology and specifically its porosity and the degree of pores interconnection. A human osteoblasts cells line (MG-63) was cultured onto the scaffold and the effect of stimulation with shock waves on the cell ability of colonizing the scaffold was investigated.

The paper reports the synthesis of an ordered silica mesostructure of the SBA-15 type inside a macroporous bioactive glass-ceramic scaffold of the type SiO(2)-CaO-K(2)O, to combine the bioactivity of the latter with the release properties of the former, in view of local drug delivery from implants designed for tissue engineering. The standard procedure for SBA-15 synthesis has been modified to minimize the damage to the scaffold caused by the acidic synthesis medium. The composite system has been characterized by means of Scanning Electron Microscopy (coupled with EDS analysis), Small Angle X-Ray Diffraction, Thermogravimetry analysis and Infrared Spectroscopy: the formation of a well ordered hexagonal mesostructure was confirmed. Ibuprofen has been chosen as model drug. The uploading properties have been investigated of the scaffold-mesoporous silica composite as compared with the scaffold as such, and a five-fold increase in the adsorbing properties toward ibuprofen was found, due to the presence of the ordered mesoporous silica. The ibuprofen release to a SBF solution in vitro is complete in 1 day. Retention of bioactivity from the glass-ceramic scaffold after the silica mesostructure incorporation has been observed.

Magnetic induction hyperthermia is a promising technique aimed at the treatment of cancer cells; however, the efficiency of the heat release is determined by the magnetic stability of the system. Ferrimagnetic glasses composed of magnetite and hematite crystals in a glassy matrix were prepared by melting of commercial reagents. The time evolution of the magnetic remanence was studied by submitting each sample to a saturating field of 20 kOe for 300 s. After sudden removal of the magnetic field, the evolution of the magnetic remanence was recorded for times up to 5times104 s. In all cases, the remanent magnetization exhibits a nonsaturating, monotonic decrease of its magnitude. The results are interpreted in terms of rearrangements of disordered magnetic volumes at interfaces between adjacent magnetite crystals.

A bioactive silica-based glass powder (SBA2) was doped with silver (Ag(+)) ions by means of an ion-exchange process. Scanning electron microscopy (SEM), energy dispersion spectrometry (EDS) and x-ray diffraction (XRD) evidenced that the glass powder was enriched with Ag(+) ions. However, a small amount of Ag2CO3 precipitated with increased Ag concentrations in the exchange solution. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of Ag-SBA2 towards Staphylococcus aureus were also evaluated and were respectively 0.05 mg ml(-1) and 0.2 mg ml(-1). Subsequently, Ag-SBA2 glass was used as filler (30%wt) in a commercial formulation of bone cement (Simplex(™) P) in order to impart both antibacterial and bioactive properties. The composite bone cement was investigated in terms of morphology (using SEM) and composition (using EDS); the glass powder was well dispersed and exposed on the cement surface. Bioactivity tests in simulated body fluid (SBF) evidenced the precipitation of hydroxyapatite on sample surfaces. Composite cement demonstrated antibacterial properties and a compressive strength comparable to the commercial formulation.

A proper stimulation of the cell activity is the last request to the new biomaterials, intended for bone substitution and osseointegration. In this regard, the scientific literature suggests that the surface modification on a nanoscale is a major source of innovation. The nano features and multiscale topographies can stimulate cell differentiation and activity. Moreover, the presence of specific biological molecules grafted onto the biosurfaces can properly stimulate cells to tissue regeneration. The final aim is to promote a fast and physiological bone healing, at the implant site. In order to be suitable for implantation, the modified surfaces must sustain the implantation and working load/friction without damages. Two different innovative surface modifications of the Ti6Al4V alloy were tested in this research. The first one is an inorganic modification and it is aimed at inducing in vivo apatite precipitation (inorganic bioactivity) and cell interaction through nano features. The modified surface shows a complex topography (micro and nanoroughness), a modified surface chemistry (high density of hydroxyls groups), high wettability and protein absorption. Moreover, an additional biological modification by grafting of alkaline phosphatase (ALP) was tested. The modified surfaces were compared with the traditional polished and blasted ones, in terms of osteoblast adhesion, proliferation and morphology. A significant increase in the cell proliferation rate was observed on the modified materials. Moreover, the osteoblasts showed a more differentiated aspect and filopodia exploring the nanotextures on both the treated materials.

Magnetic materials play a key-role in magnetic induction hyperthermia for the treatment of cancer. In this paper, we analyse the magnetic properties of ferrimagnetic glass-ceramics with the composition in the system SiO2–Na2O–CaO–P2O5–FeO–Fe2O3, as a function of the melting temperature. These materials were obtained by melting of commercial reagents in the temperature range of 1400–1550 °C. Room-temperature magnetic measurements were performed by means of a vibrating sample magnetometer at room temperature. The power loss was determined from calorimetric measurements, using a magnetic induction furnace. The highest power loss (61 W/g) has been obtained for samples melted at 1500 °C. The heat generation of the ferrimagnetic glass-ceramics prepared by two different synthesis methods (traditional melting and coprecipitation-derived) will be compared. These materials are expected to be useful in the localised treatment of cancer.

Ferrimagnetic glass-ceramic materials are promising candidates for destruction of cancerous cells by hysteresis loss, as a consequence of the increase of the local temperature when an alternating magnetic field is applied. The glass-ceramics prepared in this work contain magnetite and hematite crystals in a glassy matrix. They can be prepared by melting the coprecipitation-derived precursors at temperatures higher than 1400°C. The influence of the melting temperature on the magnetic properties of these glass-ceramics has been analysed. Room temperature hysteresis cycles in quasi-static conditions were performed using two different magnetic field, one of 12 kOe, and the other one of 500 Oe. The heat generation was estimated from calorimetric measurements, using a magnetic induction furnace. The magnetic hysteresis parameters are strongly affected by the glass-ceramics microstructure, which is influenced by the melting temperature.

Highly bioactive scaffolds for tissue engineering were synthesized using a glass belonging to the SiO2-CaO-K2O (SCK) system. The glass SCK was prepared by a traditional melting-quenching route and its bioactivity was assessed by in vitro tests in a simulated body fluid (SBF). The glass was ground and sieved to obtain powders of specific size that were subsequently mixed with polyethylene particles of two different dimensions. The powders were then uniaxially pressed to obtain a crack free green compact that was thermally treated to remove the organic component and to sinter the inorganic phase. The obtained biomaterial was characterised by means of X-ray Diffraction, SEM equipped with EDS, mercury intrusion porosimetry, density measurements, image analysis, mechanical tests and in vitro evaluations. A glass-ceramic macroporous scaffold with a homogenously distributed and highly interconnected porosity was obtained. The amount and size of the introduced porosity could be tailored using various amounts of polyethylene powders of different size.

In the last years different types of surface modifications were developed with the aim of improving the osteointegration ability of titanium alloys. The chemical composition, crystallographic structure and morphology of a surface layer can be modified in order to obtain a better interaction between the implant, the cells and the organic fluids. The final goal is to obtain a more efficient bone growth also in critical clinical cases. In the present paper were reported several data about the characterization of the Ti-6Al-7Nb alloy treated by two innovative surface treatments. They consist of blasting, followed by a two step chemical etching and heat treatment performed in air or in vacuum. TEM, XRD and SEM investigations were performed in order to assess the structure and morphology of the modified surfaces. The surface chemical composition was investigated by XPS ad AES analyses. The ability to interact with physiological fluids was tested by immersion of the treated materials in an acellular simulated body fluid (SBF). Metal ion concentration analyses of the fluid and SEM observations of the samples were performed after different times of soaking. The mechanical characterization involved scratch and fatigue tests. The surface of treated samples shows chemical, structural and morphological modifications. The passivation pre-treatment has influence on the surface modification. The treated samples evidenced a quite low metal ion release and interact with SBF solution, showing a moderate bioactivity. A relevant decrease in fatigue strength was observed on modified samples.

Glazing of alumina substrates was performed in order to prepare bioactive glass-ceramic coatings for biomedical applications. The coating material was a fluoroapatite-containing glass-ceramic (SAF) with a good degree of bioactivity. A careful optimisation of the coating conditions was carried out. The obtained coatings were characterized by means of scanning electron microscopy (SEM), compositional analysis (EDS), X-Ray diffraction (XRD), and in vitro tests (soaking into a simulated body fluid). Direct firing of SAF powders on the ceramic substrates gave unsatisfactory results in terms of crack propagation and bioactivity, due to the nucleation of a non-bioactive Al-rich phase (leucite) with high linear expansion coefficient. The use of an intermediate layer based on a SiO2-CaO glass (SC) was necessary in order to avoid Al ions diffusion through the coating and thus the formation of undesired additional phases. The coatings obtained with the optimised processing parameters resulted to be adherent, defect-free, and characterized by unchanged composition and structure as well as unmodified bioactivity if compared with the bulk SAF glass-ceramic.

In the present research work, the preparation and characterization of bioactive glass-ceramic scaffolds for bone substitutes are described. The scaffolds were prepared by starch consolidation of bioactive glass powders belonging to the SiO2-Na2O-CaO-MgO system using three different organic starches (corn, potatoes and rice) as reported in a previous screening process. The scaffolds, characterized by scanning electron microscopy, showed a porous structure with highly interconnected pores. The pores sizes assessed by mercury intrusion porosimetry put in evidence the presence of pores of 50-100 microm. The structure of the scaffolds was investigated by X-ray diffraction and revealed the glass-ceramic nature of the obtained material. The mechanical properties of the scaffolds were evaluated by means of compressive tests on cubic samples and the obtained results demonstrated their good mechanical strength. The in vitro bioactivity of the scaffolds was tested by soaking them in a simulated body fluid (SBF) and by subsequently characterizing the soaked surfaces by SEM, EDS and X-ray diffraction. Good in vitro bioactivity was found for the starting glass and for the obtained scaffolds. Moreover, the scaffold bioresorption, tested by measuring the samples weight loss in SBF at different periods of time, showed a partial resorption of the scaffolds. Cell culture testing of the three different scaffolds indicated no differences in cell number and in alkaline phosphatase activity; the morphology of the osteoblasts showed good spreading, comparable to bulk material which was used as the control.

Ferrimagnetic glass–ceramics are potential candidates for magnetic induction hyperthermia, which is one form of inducing deep-regional hyperthermia, by using a magnetic field. The aim of this work was to analyse the influence of the amount of crystallised magnetite on the magnetic properties of glass–ceramic samples. Thus, two different ferrimagnetic glass–ceramics with the composition of the system Na 2 O–CaO–SiO 2 –P 2 O 5 –FeO–Fe 2 O 3 were prepared by melting at 1500 °C for 30 min of the coprecipitation-derived starting products. The X-ray diffraction patterns show the presence of nanometric magnetite crystals in a glassy matrix after cooling from melting temperature. The estimated amount of crystallised magnetite varies between 20 and 45 wt.%, as a function of the chemical composition. The morphology of the crystals was studied by scanning electron micrography and transmission electron micrography. Glass transition temperature and thermal stability were investigated by differential thermal analysis. Magnetic hysteresis cycles were analysed using a vibrating sample magnetometer with a maximum applied field of 17 kOe, at room temperature, in quasi-static conditions. Calorimetric measurements were carried out using a magnetic induction furnace. The power losses estimated from calorimetric measurements under a magnetic field of 40 kA/m and 440 kHz are 65 W/g for the glass–ceramic with lower iron oxides content and 25 W/g for the glass–ceramic with higher iron oxide content.

Novel bioactive materials have been prepared by coating violet resorbable Vicryl® sutures with a bioactive glass powder derived from a co-precipitation method. Two techniques have been chosen for the composite preparation: pressing the sutures in a bed of glass powder and slurry-dipping of sutures in liquid suspensions of bioactive glass powders. The uniformity and thickness of the coatings obtained by the two methods were compared. The bioactivity of the sutures with and without bioactive glass coating was tested by soaking in an inorganic acellular simulated body fluid (SBF). The composite sutures were characterised by XRD, SEM and FTIR analyses before and after soaking in SBF solution to assess the formation of hydroxyapatite on their surfaces, which is a qualitative measure of their bioactivity. The possible use of bioactive sutures to produce tissue engineering scaffolds and as reinforcement of resorbable calcium phosphates is discussed.

Ti-6Al-7Nb samples treated by innovative multi-step chemical and thermal processes were characterized in order to evaluate their surface properties and cell interaction. The main object was to asses if the treatments were effective in order to obtain a surface presenting at the same time bone-like apatite induction ability, low metal ion release, good cell response and high protein binding. The morphology, crystallographic structure, porosity and wettability of the treated materials were investigated, as well as their interaction with simulated body fluid during soaking for different times. Cytotoxicity, protein adsorption tests and in vitro fibroblast and osteoblast-like cell cultures were also performed.

In the present research work, glass powders and three different organic starches were used to realize macroporous glass-ceramic scaffolds for bone substitutions. For this purpose, bioactive glass powders belonging to the system SiO2–CaO–Na2O–MgO were mixed in a liquid medium with the desired amount of the selected organic phase. Afterwards, by progressively raising the temperature, the water uptake of starches occurred and led to the gelling of the whole system. The resultant gel underwent two thermal treatments in order to eliminate the organic phase and to allow the sintering of the glassy phase. In this way, macroporous glass-ceramic scaffolds were successfully prepared. The samples were characterized by means of optical and scanning electron microscopy with compositional analysis. The volume and mean size of the obtained porosity were investigated by means of mercury intrusion porosimetry, whereas its morphology was assessed by means of microscopic observations. The structure of the original and the resultant materials were investigated by X-ray diffraction. In order to study the reactivity of the scaffolds towards physiological media, the samples were soaked in a simulated body fluid for various times. On their soaked surfaces, scanning electron microscopy and compositional analysis were carried out in order to assess their bioactivity.

Double-layer bioactive glass-ceramic coatings were prepared on Ti–6Al–4V substrates by dipping and firing. A SiO 2 –CaO–Na 2 O–MgO–P 2 O 5 –K 2 O (SCP) based glass was used as first layer in direct contact with the metallic substrate and a SiO 2 –Al 2 O 3 –P 2 O 5 –K 2 O–CaO–F − (SAF) based glass-ceramic was used as outer bioactive layer. The deposition of the intermediate SCP layer was necessary in order to obtain a good adhesion of the coating to the substrate, to minimize the reactivity between the substrate and the outer glass-ceramic coating and thus to preserve the nature of its crystalline phases. The coated samples were characterised by means of X-ray diffraction (XRD), scanning microscopy (SEM), and compositional analyses (EDS). The bioactivity of the coated samples was studied by soaking them in simulated body fluid (SBF) in order to observe the growth of an apatite layer on their surface. The optimised coating method was then used to coat Ti6Al4V screws for dental applications.

It was recently claimed that titanium metal and its alloys can bond to the living bone, without being coated by apatite (VPS coatings), but by being chemically and heat-treated. The bioactivity of treated titanium is of interest because of the opportunity to obtain orthopaedic or dental implants presenting, at the same time, high toughness, strength and fatigue resistance as well as bone-bonding ability. The bioactive behaviour of the treated implants is due to the presence of a modified surface, which, during soaking in body fluid, promotes the precipitation of apatite. The apatite formed is strongly bonded to the substrate and promotes living bone bonding. In this work were characterised samples of Ti-6Al-7Nb alloy with surfaces presenting a different chemical and mechanical state. The aim of the research was twofold. The first objective was to characterise chemically and heat-treated samples with different surface topography, in order to define the best conditions for osteogenic integration. The second aim was to assess the corrosion behaviour of the bioactive implants, because they expose a microporous and quite thin modified surface layer. No-treated and passivated samples, with a surface state closed to that nowadays used on implants, were used as reference. The surface structure, morphology, electrochemical behaviour and bioactivity of the different samples were assessed by means of XRD, SEM-EDS, anodic polarizations, open circuit measurements and in-vitro tests. Results evidence that it is possible to modify the surface of the Ti-6Al-7Nb alloy in order to obtain the formation of a bioactive layer and that the substrate roughness influences the characteristics of the surface layer formed. It was also evidenced that the as treated surfaces present inadequate corrosion behaviour, so a new two-step chemical treatment has been developed in order to obtain a bioactive material with good corrosion resistance.

The aim of this work was to realise bioactive coatings on full density α -alumina substrates. An SiO 2 –CaO-based glass (SC) and an SiO 2 –Al 2 O 3 –P 2 O 5 –K 2 O–CaO–F − -based glass-ceramic (SAF) were used for this purpose. Specifically, SAF is a fluoroapatite containing glass-ceramic and previous studies have shown that it is a highly bioactive biomaterial. Furthermore, these fluoroapatite crystals possess a needle-shaped morphology which mimics that of hydroxylapatite found in human hard tissues, particularly in teeth. SAF is a very viscous glass-ceramic and for this reason an intermediate, less viscous, SC layer was interposed in direct contact with alumina aiming to obtain a good coating adhesion. Moreover, this intermediate layer strongly lowers the Al 3+ diffusion and thus minimises both compositional changes in the SAF outer layer and the risk of detrimental modifications of the nature of the crystalline phases. A complete characterisation of the coated samples was performed by means of X-ray diffraction, optical and scanning microscopy. Coating adhesion on alumina was tested by comparative shear tests while biocompatibility was investigated on alumina, bulk SAF and on the realised coatings. For this purpose, cytotoxicity, adhesion and proliferation of human osteoblast-like cells were cultured onto the three materials. Results showed that the interposition of the SC layer was successful in allowing a good softening and spreading of the SAF outer layer and in avoiding the crystallisation of undesired crystalline phases maintaining the good bioactive properties of the bulk one. In vitro results on the coatings showed osteoblast-like cell behaviour similar to bulk fluoroapatite glass-ceramic and better respect to alumina substrates, being a promising index of bone material integration and of its in vivo possible applications.

A SiO 2 –CaO–Na 2 O (SCN) based bioactive glass was used to prepare glass–matrix/Ti particle composite coatings (SCNT). The coatings were obtained by vacuum plasma spray (VPS) on Ti–6Al–4V substrates. Two different deposition methods have been compared: (a) VPS of powders obtained by ball milling of sintered composites; (b) in situ plasma spray of mixed titanium and glass powders. For comparative purposes, pure SCN glass coatings were produced. The coating morphology and microstructure were observed by optical and scanning electron microscopy, compositional analyses by energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Comparative mechanical tests were carried out by shear tests and by Vickers indentations at the interface between the substrate and the coatings. The bioactivity of glass- and composite coatings was investigated in vitro by soaking them in a simulated body fluid (SBF) with the same ion concentration of the human plasma. All the layers retain their starting composition. The composite coatings obtained by VPS of the powdered presintered composites showed a better mechanical behaviour with respect both to the composite coatings obtained by the in situ method and to the pure glass coatings. Both the glass- and the two kind of composite coatings revealed to be bioactive by the growth of a thick apatite layer after 30 days of soaking in SBF. The electrochemical behaviour of the SCNT coatings was evaluated by means of potentiodynamic anodic polarization curves and free corrosion potential measurements in Ringer solution at 25 °C. For comparative purposes the same analyses were performed on analogous bioactive glass-matrix/Ti particle composite coated samples, based on the system TiO 2 –SiO 2 –CaO–B 2 O 3 (TSCB), and obtained both by the in situ and by presintering method as well. The results of the electrochemical tests showed a better corrosion behaviour of the samples coated by VPS of powdered sintered composites with respect to those coated by in situ VPS composites.

An in vitro evaluation of a biomedical device, which combines the mechanical properties of zirconia substrates with the bioactivity of two different glass layers (AP40 and RKKP), was performed. In this work, data on different kinds of analysis were reported both on as-sintered zirconia samples and on RKKP- and AP40-coated zirconia substrates. Structure, composition and morphology of the apatite layer growth on the coated samples after 30 days of soaking in an acellular simulated body fluid, serum protein adsorption, fibroblasts and human osteoblast-like cells adhesion, growth, morphology and biochemical aspects were studied. Results of soaking test in SBF, revealed the growth of an apatite layer on the surface of the glass-coated samples. Proteins adsorbed to the materials were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and results evidenced that the two glass-coated materials bound a higher amount of total protein than did the zirconia substrate. Fibroblasts and osteoblast-like cells cultured on RKKP- and AP40-coated zirconia showed a higher proliferation rate, leading to confluent cultures with higher cell density and a generally better expression of osteoblast alkaline phosphatase activity in comparison with zirconia substrate. In conclusion, our results indicate that the surface chemical characteristics of the two glass coatings AP40 and RKKP, with no great differences between them, substantially enhance zirconia integration with bone cells at least in vitro. This effect may be of significance in the stability of glass-coated zirconia orthopaedic and dental implants.

Bioactive glasses and particles reinforced composites were used to coat alumina substrates, in order to combine the mechanical properties of the high-strength alumina with the bioactivity of the coatings. The coatings were either monolithic glass or glass-matrix/zirconia particle composite and were prepared by a low-cost firing method. A multilayer approach was applied to minimize crack propagation at the interface between the coating and the substrate. Functionally graded structures were developed to achieve a compliant material to withstand the stresses due to the expansion coefficient mismatch between the substrate and the coatings. The sequential coating of the alumina with glass-matrix/zirconia particle composite layers produced a structurally stable composite structure. A systematic study revealed that multiple layers were necessary to provide a gradual compliance of the thermal expansion coefficient. The glass-matrix/zirconia particles composites layers were also essential for the control of the Al 3+ diffusion from the substrate through the glass. This is in accordance with the experimental results of previous works. Thus, the alumina content in the coating should be maintained as low as possible in order to preserve its bioactivity. The composite layers were further coated by a glass belonging to the system SiO 2 –CaO–P 2 O 5 –Na 2 O–MgO–F − , known for its bioactivity. The experimental results were substantiated by optical and scanning electron microscopy (SEM) with compositional analysis (EDS) and by a mechanical characterization. The in vitro behavior of the coated samples was investigated by means of soaking in simulated body fluid (SBF) followed by SEM observation and XRD analysis.

Pure full-density alumina substrates were coated by a bioactive glass-ceramic belonging to the system SiO 2 -Al 2 O 3 -P 2 O 5 -Na 2 O-K 2 O-CaO-F − . Through a careful optimization of the coating process, we obtained coatings approximately 200 microns thick. The interface between the substrates and the coating material was characterized by optical microscopy, X-ray diffraction (Philips PW1830), scanning electron microscopy (SEM, Philips 525 M), and compositional analyses (Energy Dispersive Spectroscopy, EDS-EDAX 9100). The interface substrate/coating was homogeneous and the composition of the coating (analyzed by EDS) did not reveal deep modifications.

In order to combine the mechanical properties of a high-strength inert ceramic (yttria-stabilised zirconia, ZrO 2 –3%Y 2 O 3 , defined as zirconia in the text) with the specific properties of bioactive materials, some zirconia samples were coated by two bioactive phosphosilicate glasses and glass-ceramics: RKKP and AP40. Coatings of about 200–300 μm thickness were prepared by a simple and low-cost firing method. They were characterised by optical and scanning electron microscopy (SEM) and compositional analysis (EDS). The adhesion of the coatings on zirconia was tested by shear tests. Vickers indentations at the coating/zirconia interface were performed in order to observe the crack propagation path. The reactivity of glasses and glass-ceramics coatings towards a simulated body fluid (SBF), having the same ion concentration as that of human plasma, was evaluated and compared to that of the bulk glass and glass-ceramics, by examining the morphology of the reaction layer formed on the surface of the coated zirconia after one month of soaking in the SBF at 37°C.

Bioverit®I is a bioactive glass–ceramic used for bone substitutions in several fields of human surgery. In this work, the possibility of using Bioverit®I as matrix of a biocomposite toughened by Ti particles, in order to toughen this glass–ceramic and to widen its application fields, was investigated. Bioverit®I base glass matrix/Ti particle biocomposite (B1T) coatings were prepared by vacuum plasma spray (VPS), by spraying a mixture of glass powders and 15 vol% titanium particles on Ti–6Al–4V substrates. The composite coatings were prepared starting from the base glass powders, in order to fully utilise the softening properties of this material in its amorphous state. The coatings were characterised by optical and scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS) and X-ray diffraction (XRD). Vickers indentations at the interface between the substrate and the coatings and shear strength measurements were performed in order to analyse the adherence of the coatings to the substrate. The surface reactivity of the coatings was evaluated by soaking the coated samples in a simulated body fluid (SBF) having the same ion concentration as the human plasma and by analysing the Si, Ca and P ion concentration while soaking.

The aim of this work is the optimization of the sintering process of particle-reinforced glass matrix composites to obtain densities as close as possible to the theoretical value and improved mechanical properties in comparison with the parent glass matrix. A pressureless sintering process has been studied by means of heating-microscopy, differential scanning calorimetry and dilatometry on glass powders and mixtures of glass and reinforcement powders. The chosen glass matrix composites have the following compositions: (1) 5, 10 and 20 wt% Ti particlereinforced ZnOB 2 O 3 PbO based glasses; and (2) 5, 10 and 20 wt% Ti particle-reinforced TiO 2 ZnO B 2 O 3 PbO based glasses. These glasses are suitable as ‘model’ glasses, but the method can be extended to any other matrix.

Differential scanning calorimetry (DSC) is used in order to investigate the aging behaviour of AlCuMg alloys with different Cu:Mg ratios. Mechanism and kinetics of aging for these materials are compared with those of an (AlCuMg)-SiC composite. DSC results are in fairly good agreement with metastable AlCu and AlCuMg phase diagrams. The SiC reinforcement does not affect the precipitation path; furthermore, the activation energy for θ″ precipitation, calculated by Ozawa's method, is not appreciably different, taking into account the experimental error, for unreinforced alloy and composite. However, all the transformations involved in the aging sequence are shifted towards lower temperatures during the DSC scans of the composite material.

The advancement of the healthcare and biomedical sectors requires the improvement of traditional biomaterials and the development of new and multifunctional biomaterial combinations with enhanced structural and biological performance. The need for biomaterials to help tackle the health problems of an increasing elderly population is continuously growing. Biomaterials science and technology is highly interdisciplinary, which involves not only the established materials science disciplines but also scientific fields such as chemistry, biology, bioengineering and medicine. The increasing impact of nanotechnology in the medical field must also be noted as this implies the development of biomimetic surfaces, nanostructured biomaterials and miniaturized devices. At the last European Congress and Exhibition on Advanced Materials and Processes (EUROMAT 2011: http://euromat2011.fems.eu) held in Montpellier, France in September of last year, the topic of materials for healthcare was covered in three focused symposia, namely: i) bioactive coatings and material-tissue interfaces, ii) smart and biomimetic materials for biomedical applications and tissue engineering and iii) mechanical characterization and modeling of tissues and biomedical materials at all length scales. The oral and poster presentations reflected novel research on biomaterials covering new areas of processing, properties and applications of materials in the biomedical field. A broad variety of topics were presented, ranging from biomaterials for bone replacement, bioactive surfaces and coatings, nanocomposites and tissue engineering scaffolds, bioinspired biocomposites and antibacterial coatings. The eight papers [1–8] published in this special issue of Biomedical Materials were selected from contributions presented at EUROMAT 2011 in the Materials for Healthcare Symposia, specifically for their focus in biomaterials for tissue engineering. It is recognized that successful biomaterials and structures for tissue engineering are those that closely mimic the composition chemistry and hierarchical structure of the native tissues to be replaced and regenerated, including the possibility of adaptation to the biological changes during the healing process, and which exhibit specific mechanical and biological functions to enable rapid new tissue regeneration. The papers selected for this special section went through the normal peer-review process of the journal and cover numerous novel biomedical materials, including a range of inorganic and functionalised bioactive coatings for prosthetic and bone regeneration applications, a series of advanced biodegradable polymer-inorganic composites for tissue engineering and engineered nanocarriers for gene delivery also discussing the interaction of scaffolds with different stem cells. As guest editors of this special section in Biomedical Materials, we are grateful to all authors and reviewers, who have supported this publication with their efforts and hard work, contributing to its timely publication. References [1] Demnati I, Grossin D, Combes C, Parco M, Braceras I and Rey C 2012 Biomed. Mater. 7 054101 [2] Ferraris S, Pan G, Cassinelli C, Mazzucco L, Verne E and Spriano S 2012 Biomed. Mater. 7 054102 [3] Hild N, Fuhrer R, Mohn D, Bubenhofer S B, Grass R N, Luechinger N A, Feldman K, Dora C and Stark W J 2012 Biomed. Mater. 7 054103 [4] Luz G M and Mano J F 2012 Biomed. Mater. 7 054104 [5]Garcia-Garcia J M, Garrido L, Quijada-Garrido I, Kaschta J, Schubert D W and Boccaccini A R 2012 Biomed. Mater. 7 054105 [6] Ojea-Jimenez I, Tort O, Lorenzo J and Puntes V F 2012 Biomed. Mater. 7 054106 [7] Handel M, Hammer T R and Hoefer D 2012 Biomed. Mater. 7 054107 [8] Pascaud P, Bareille R, Bourget C, Amedee J, Rey C and Sarda S 2012 Biomed. Mater. 7 054108

In order to widen the application fields of a bioactive glass-ceramic (Bioverit 1 I), the possibility of preparing a glass-ceramic matrix biocomposite, toughened by zirconia particles, was investigated. Two kinds of biocomposites were prepared, using as reinforcing phase tetragonal yttria-stabilised zirconia (ZrO2–3%Y2O3) and pure monoclinic zirconia particles, respectively. The composites were prepared by viscous flow sintering. The sintered composites were characterised by optical and Scanning Electron Microscopy (SEM), Energy Dispersion Spectroscopy (EDS) and X-Ray Diffraction (XRD). A mechanical characterisation of the sintered samples was carried out by means of Vickers indentations, Young’s modulus measurements, fracture toughness and compressive strength determinations. The chemical stability of the samples was evaluated by soaking them in Ringer solution. # 2002 Published by Elsevier Science Ltd.

Electrical resistance, magnetization, and magnetoresistance have been measured as functions of temperature from 50 to 300 K on three ferromagnetic glass ceramics containing different magnetite crystals by preparing conditions and crystal morphology. Magnetite crystals form a percolating network for electrons with weak links at crystal-crystal contact points. All samples exhibit a broadened Verwey transition, peaked at temperatures lower than measured in bulk stoichiometric magnetite. The negative magnetoresistance ratio increases in absolute value with sample cooling from RT down to the Verwey temperature and decreases on further cooling. This behavior indicates that electron transfer between magnetite crystals is achieved through spin-dependent and spin-independent channels acting in parallel. Magnetic correlation states for spins at contact points between magnetite crystals are studied by plotting the magnetoresistance as a function of reduced magnetization. The transition from activated hopping to variable range hopping affects the magnetoresistance versus magnetization curves.

CaO-SiO2 base glass-matrix/Ti particle biocomposite coatings on Ti6Al4V substrates have been prepared by means of Vacuum Plasma Spray. The base glass is considered bioactive, because, when soaked in a fluid that simulates the inorganic ion concentration of human plasma (SBF), it develops a bonelike apatite layer on its surface. The aim of this research activity was to toughen this brittle bioactive material and to broaden its biomedical applications. Pure titanium was chosen as toughening phase because of its well-known biocompatibility, and Ti6Al4V alloy as substrate because of both its biocompatibility and its mechanical reliability. At first the composites were prepared as bulk materials, by means of a simple sintering process. Then, by ball-milling the sintered composite, the as-obtained “composite powders” were sprayed by Vacuum Plasma Spray (VPS) on the substrate. By means of Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC), the characteristic temperatures of the base glasses were determined. The thermal properties of mixtures of glass powders and different vol% Ti particles were studied by means of DTA, DSC, hot-stage microscopy, and dilatometry, with the aim of optimizing the sintering conditions. Both the bulk and the coated samples have been characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), compositional analysis (EDS), Vickers indentations, and leaching tests after soaking in a simulated body fluid (SBF). © 2000 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 53: 408–413, 2000

A bioactive glass belonging to the system SiO(2)-CaO-Na(2)O was doped with silver ions by ion exchange in molten salts as well as in aqueous solution. The ion exchange in the solution was done to check if it is possible to prepare an antimicrobial material using a low silver content. The doped glass was characterized by means of X-ray diffraction, SEM observation, EDS analysis, bioactivity test (soaking in a simulated body fluid), leaching test (GFAAS analyses) and cytotoxicity test. It is demonstrated that these surface silver-doped glasses maintain, or even improve, the bioactivity of the starting glass. The measured quantity of released silver into simulated body fluid compares those reported in literature for the antibacterial activity and the non-cytotoxic effect of silver. Cytotoxicity tests were carried out to understand the effect of the doped surfaces on osteogenic cell adhesion and proliferation.

In this work a Bioverit®III glass-ceramic matrix composite, containing Yttria-stabilised zirconia (Y-PSZ) particles as toughening phase, was prepared, with the aim of improving the glass-ceramic mechanical properties. In order to prepare the composite, a pressureless sintering process has been optimised. The aim of the work is to determine the best processing conditions, i.e. time and temperature of sintering. For this purpose traditional methods (thermal, morphological and mechanical analysis) have been supported by the statistical method called ”Response Surface Methodology” (RSM). On the basis of these studies two sintering series have been performed, so that we could determine the region where the best process conditions could be found.