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International audience; Fluoride (F) is important for enhancing illogical activity of bioceramics. To increase fluoride content of derived Hench bioactive glass (BaG), bioactive fluorosilicate glasses (BaG-Fx) were synthesized by using melting method and characterized using different physico-chemical analyses. Fluoride-containing BaGs were synthesized at a temperature of 1350 degrees C. Structural and thermal effect of calcium fluoride (CaF2) insertion into the glass network in the BaG: SiO2-CaO-Na2O-P2O5 quaternary system was studied. Indeed, the incorporated amounts of fluorine (CaF2) (from 5% to 20% by mass) induced significant physico-chemical changes. Through the structural study by X-ray diffraction (XRD), the amorphous character of our fluorosilicate glasses is proven. Infrared (IR) spec-troscopy proved the incorporation of fluorine into the glass matrix. In the microstructural framework, we revealed the morphological changes of the glass powders as a function of the CaF2 content. These results were confirmed by Brunauer, Emmett and Teller (BET) measurements. Through Differential Scanning Calorimetry (DSC) thermal analysis we established the impact of fluoride ions on the structural dynamics and thermodynamic properties of these newly developed bioactive glasses. Accordingly, it was possible for the first time to incor-porate as much as 20 wt% of CaF2 in BaG respecting the conditions of bioactivity and biodegradability required by Hench. After detailed analyses of the transformation entropies of BG-Fx as a function of the added CaF2 content, it can be stated that the intermolecular movements within the fluorosilicate network are more limited as a function of the added CaF2 amount. This slows down the ion exchange phenomena and subsequently the dissociation of the material in vitro, which can be anticipated to occur after implantation in vivo.

International audience; Three-dimensional hydroxyapatite-chitosan (HA-CS) composites loaded with ciprofloxacin antibiotic (HA-CS-CIP) were formulated using the in situ and the solid-liquid method coupled with the freeze-drying process. The interaction of the HA-CS composite powder and ciprofloxacin antibiotic (CIP) was investigated by batch adsorption essays. The kinetic and the isotherm data were fitted well to the pseudo-second-order and Freundlich models, respectively. The compressive strength of the HA-CS composite was increased by 7-fold and 10-fold when using respectively 15 wt% and 30 wt% of the polymer compared to the HA-CS5 formulation (3.6 +/- 0.7 MPa) made only from HA powder and CS gel (5 wt%). However, this parameter decreased from 36.8 +/- 8.5 MPa down to 20.5 +/- 4.7 MPa when the antibiotic content increased from 0 up to 9 wt%, respectively. The in vitro release results showed a sustained and controlled CIP release for up to 10 days. The release data fitting and modeling indicate that the process follows a Fickian diffusion mechanism. Also, the formulated composite revealed an antibacterial effect against Staphylococcus aureus and Escherichia coli bacteria. The developed

International audience; Monoammonium phosphate is a commonly used fertilizer for better crop production. However, its repeated application causes the accumulation of harmful metals levels in plants and soil over time. Here, the impact of the purification of monoammonium phosphate fertilizer on vegetative growth and yield of tomato plants (Lycopersicon esculentum L.), and the heavy metals accumulation in both soil mix and tomato fruits was investigated through a pot experiment on three different concentrations of purified and unpurified monoammonium phosphate fertilizer. This study showed that the purification of monoammonium phosphate led to a significant enhancement on vegetative growth and yield attributes, mainly for 1 g/L of purified fertilizer. Importantly, the physicochemical investigations showed a significant reduction in heavy metals accumulation (Pb, Cr, Cd, Ni, and V) in the fruits and the soil mix treated with purified monoammonium phosphate. This study confirms that the use of purified monoammonium phosphate fertilizer improves the fruit yield and at the same time reduces the impact of toxicity of heavy metals present in the environment, which can be classified as a part of an environmental management systems.

International audience; A composite based on hydroxyapatite (HA) and chitosan (CS) combined with ciprofloxacin (CIP) was formulated by the solid-liquid mixing method. The optimization of the solid to the liquid ratio and the use of chitosan in a small amount (

International audience; The ovariectomized (OVX) rat model is well established in investigations of osteoporosis and anti-osteoporotic therapies. Fourier transform infrared (FTIR) spectroscopy facilitates characterization of bone quality which is a key determinant of bone strength. FTIR has been used to evaluate the changes occurring in the mineral composition of lumbar vertebrae obtained from osteoporotic rats and osteoporotic rats treated with Zingiber officinale (ZO). Bone quality parameters were determined including measures of degree of mineralization, crystallinity, carbonate content, acid phosphate content and collagen maturity. The main results reveal shifts in bands position and disappearance of band in osteoporotic group. Therefore, several changes in the compositional properties of osteoporotic bone, essentially reduced mineral/matrix ratio. The data obtained from FTIR show return bands to their initial positions and the restoration of bone quality parameters following ZO treatment.

International audience; Bioactive glasses have the physical characteristics enabling them to be used in bone tissue engineering applications. However, the exact mechanism of the interactions between the glass surface and environment leading to the transition from the vitreous phase to the crystalline phase remains a subject of study. This work focuses on the growth of a calcium phosphate layer on the surface of the glass after immersion in a mineral solution, which mimics the mineral phase of human blood. The investigations use the Inductively Coupled Plasma and the Atomic Force Microscopy to establish the kinetic of crystallization, the kinetic of chemical reactivity and the surface transformations such as structure, texture and morphology of the bioactive glass. Obtained results show the progressive formation of a hydroxyapatite layer within 2 weeks. This crystal which is that of the bone belongs to the crystallographic structure within space group of P63/m. In addition, results show a decrease of the gradient of thickness which varies according to the immersion time from 7.5 µm to 2.8 µm and an increase of the homogeneity of the surface visible by the lowering of the gradient in the phase measurement from 60 Å to 15 Å.

International audience; The damage to normal bone tissue following therapeutic irradiation increases the risk of fracture and bone osteoporosis. Bioactive glasses have been synthesized with improved properties exhibiting promising prospects to restore bone defects and to reduce bone alterations. This study aims in evaluating the performance therapy of nano-bioglass (NBG). In vivo, after rat Co-60 y-radiation, the tissue wound healing process was studied by grafting NBG material in rat femoral condyle tissue. An improved mechanical property was noticed (31.11 +/- 5.0 HV) when compared with that of BG-implanted group (24.16 +/- 4.9 HV). On the other hand, a rise in Ca and P ion concentrations in the implanted microenvironment was shown to lead to the formation/deposition of Ca-P phases. Trace elements, such as Mg and Zn, were detected in the newly formed bone and involved in bone healing. Serum alanine aminotransferase (ALT), aspartate transaminase (AST), and gamma-glutamyl-transpeptidases (GTT) in groups implanted with NBG show no significant variation for all time of implantation. Serum creatinine maintains their normal levels in the implanted groups in different time of implantation. The histomorphometric parameters of bone tissue showed amelioration in NBG-treated rats. Moreover, no hepatocyte or renal necrosis was noticed. Additionally, no remarkable change in the tissue morphology was shown. Our findings suggested that NBG might have promising potential applications for wound healing.

The present study aimed to enhance the anti-osteoporotic performance of bioactive glass (46S6) through its association with bisphosphonate such as risedronate with amounts of 8, 12, and 20%. Obtained composites have been called 46S6-8RIS, 46S6-12RIS, and 46S6-20RIS, respectively. In vitro and in vivo explorations have been carried out. Bioactive glass and risedronate association has been performed by adsorption process. Structure analyses have been carried out to evaluate and to understand their chemical interactions. Solid Nuclear Magnetic Resonance (NMR) has been employed to study the structural properties of obtained biocomposite. The spectra deconvolution showed the appearance of a species (Q4) in the biocomposites 46S6-8RIS, 46S6-12RIS, and 46S6-20RIS indicating their successful chemical association. In vitro experiments showed the enhancement of the chemical reactivity of the composites 46S6-xRIS compared to the pure bioactive glass. In fact, the silicon liberation after 30 days of immersion was 50 ppm for pure bioactive glass 46S6, and 41, 64, and 62 from 46S6-8RIS, 46S6-12RIS, and 46S6-20RIS, respectively. Based on the in vitro results, 46S6-8RIS was implanted in the femoral condyle of an ovariectomized rat and compared with implanted pure glass in the goal to highlight its anti-osteoporotic performance. After 60 days, implanted group with 46S6-8RIS showed the increase in bone mineral density (BMD with 10%) and bone volume fraction (BV/TV with 80%) and the decrease in trabecular separation (Tb/Sp with 74%) when compared to that of 46S6 group. These results are confirmed by the histopathological analyses, which showed the bone trabeculae reconnection after the 46S6-8RIS implantation. Chemical analyses showed the reduction in silicon (Si) and sodium (Na) ion concentrations, and the rise in calcium (Ca) and phosphorus (P) ion levels, which was explained by the dissolution of biocomposite matrix and the deposition of hydroxyapatite layer. Histomorphometric results highlighted the risedronate effect on the antiosteoporotic phenomenon. Obtained results showed good behavior with only 8% of introduced risedronate in the glass matrix.

International audience; The present research work is an in vivo study that aimed to evaluate the potential role of bioglass-chitosan (BG-CS) and bioglass-chitosan-20%ciprofloxacin (BG-CS-20Cip) in antioxidant profile and osteointegration. These scaffolds were implanted in the defect bone of femoral condyles in ovariectomized rats. The treatment with BG-CS-20Cip has shown a significantly higher stress proteins concentration in comparison with that implanted with BG-CS group. The thiol and vitamin C in BG-CS-20Cip group were significantly enhanced when compared with those in BG-CS group. The histological and physicochemical analyses highlight the BG-CS implications in the bone construction. This property was found to decrease with the presence of ciprofloxacin that caused the delay of this phenomenon. ICP-OES has revealed that the introduction of this antibiotic to the composite led to decrease bone mineralization by evaluating Ca/P ratio. The SEM results have confirmed a progressive degradation of BG-CS and BG-CS-20Cip. However, such bioresorbability and bioactivity of BG-CS was proven to be faster than those of BG-CS-20Cip. Therefore, the incorporation of ciprofloxacin in BG-CS was characterized by a delaying effect of composite dissolution and the formation of apatitic phase. The development of BG-CS as a therapeutic biomaterial protector against oxidative stress is likely to make an effective choice for the application in tissue engineering.

International audience; This study investigated the effect of bioglass (melting)-polyvinyl alcohol (BG (M)-PVA) and bioglass (melting)-polyvinyl alcohol-20 %ciprofloxacin (BG(M)-PVA-20Cip) in improving antioxidant activity and regenerating bone capacity. These composites were implanted in femoral condyles of ovariectomized Wistar rats and compared to that of controls groups. After the different period of implantation (15, 30, 60 and 90 days), the treatment of ovariectomized rats with BG(M)-PVA-20Cip showed a significantly higher malondialdehyde concentration when compared to that of BG(M)-PVA group. The superoxide dismutase, glutathione peroxidase and catalase in BG(M)-PVA-20Cip group showed significantly lower activities when compared to those in BG(M)-PVA group. So, BG(M)-PVA is more tolerated by organism than BG(M)-PVA-20Cip. Moreover, the alkaline phosphatase and acid phosphatase activities showed an excellent osteoinductive property of BG (M)-PVA. This property decreased with the presence of ciprofloxacin which is confirmed by histopathological analysis. Several physicochemical techniques showed a rapid reduction in Si and Na in one hand and an accelerator rise in Ca and P ions concentrations in other hand in BG(M)-PVA than in the BG(M)-PVA-20Cip. Therefore, the incorporation of ciprofloxacin in BG(M)-PVA is characterized by a prooxidant effect in oxidant–antioxidant balance at the beginning of treatment and a retard effect of formation of apatitic phase

International audience; The present study aimed to evaluate the effect of bioactive glass as well as the presence of Ciprofloxacin drug (%Cip) into bioactive glass–chitosan composite on the in vivo behavior of these scaffolds. These scaffolds were implanted in the femoral condyl of an ovariectomized rat. The serum and organs (liver and kidney) of the under investigated rats were analyzed. Also the physicochemical properties of the prepared implants were assessed using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) before and after implantation (at different periods of implantation). Biochemical and histological analyses of the under investigated rats proved the biocompatibility of the prepared scaffolds. The hydroxyapatite like layer was significantly precipitated on the surface of BG–CH scaffold than BG–CH–20Cip. In this same period, FT-IR of BG–CH shows complete disappearance of Si–O–Si. Their characteristics bands were replaced by P–O group arisen form bone apatite bands. Physicochemical results show progressive degradation of BG–CH and BG–CH–20Cip that occurred at the same time as replacement of the implant by an apatite layer. However, the bioresorbability and bioactivity of BG–CH are faster than those of BG–CH–20Cip. Therefore, the incorporation of the Ciprofloxacin in the BG–CH induces a retarding effect on the formation of the hydroxyapatite, and consequently on the ossification, without any side effects on the liver–kidney. © 2017, Springer-Verlag Berlin Heidelberg.

International audience; Bioactive glasses are indicated for use as bone substitutes in orthopedic or dental surgery because of their high reactivity once in contact with the biological medium. Boron is known as a glass network former and an activator of the glasses bioactivity. In this work, bioactive glass was doped by 5, 10 and 20 wt% of B2O3 according to the melting process. Adding boron oxide with high content enhances glass materials’ bioactivity. Likewise, thanks to their solubility, borate-containing bioactive glasses were fluently used as orthopedic implants. The aim of our study was to investigate of boron effect on the thermal characteristics of our bioactive glass to better understand their proprieties in order for use as bone biomaterial. The obtained results proved that the more the boron content in the glass network increases, the more the melting temperature decreases and the more the thermal stability increases

International audience; Bioactive glass particle is used in the repair of bone defects. This material undergoes a series of surface in vivo reactions, which leads to osteointegration. We evaluated the effect of the bioactive glass synthesis, sol-gel (BG(S)) versus melting (BG(M)), associated with polyvinyl-alcohol (PVA) on in vivo bioactivity with biochemical parameters, liver-kidney histological structure and antibacterial in vitro activity. These composites were testified in many bacteria and implanted in ovariectomized rat. The serum and organs (liver and kidney) of all groups, control and treated rats, were collected to investigate the side effects of our composites, BG(S)-PVA and BG(M)-PVA, in comparison with control and ovariectomized rats. Also, the implants, before and after implantation, were prepared for analysis using physicochemical techniques such as Fourier transform infrared spectroscopy and X-ray diffraction. Our results have shown the stability of natremia, kaliemia, calcemia and phosphoremia. The histological structures of liver and kidney in implanted rats are intact compared to control and ovariectomized rats. BG(S)-PVA is characterized by a higher antibacterial effect on negative and positive gram bacteria than BG(M)-PVA. The physicochemical results have confirmed a progressive degradation of BG(S)-PVA and BG(M)-PVA, while replacing the implant by an apatite layer. But this bioactivity of BG(S)-PVA is faster than BG(M)-PVA. We can therefore confirm, on the one hand, the biocompatibility of our two implants and, on the other hand, the beneficial effect of sol-gel synthesis technique versus melting, both on the antibacterial effect and on the rapid formation of layer hydroxyapatite, and consequently on osteogenesis

Objective: In the present study, we investigate the biological performance of a calcium phosphate ceramics (CPC) bone substitute combined with poly-hydroxybutyrate-co-hydroxyvalerate (PHBV). Materials and Methods: A particulate CPC [45% beta-tricalcium phosphate ([Formula: see text]-TCP) and 55% of dihydrated dicalcium phosphate (DCPD)] was incorporated into a biodegradable copolymer PHBV. Two series of the composite, 1 and 2, with CPC–PHBV weight ratios of (40%–60% and 60%–40%), respectively, were prepared using chloroform for dissolving the polymer and a pressure molding process for shaping the composite samples. After particle size analysis, the two composites were characterized by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). In a second step, a 10[Formula: see text]mm bony segmental defect created in the tibias of 20 New Zealand White Rabbits was filled randomly with either composite 1 for group 1 or composite 2 for group 2. There were 10 animals in each group. Clinical, radiological and histological assessments were then carried out to evaluate the biological properties of developed CPC–PHBV composites. Results: For both variants of the developed CPC–PHBV biocomposite, there was evidence of osseous consolidation within three months. An in vivo investigation revealed the biological properties of the biocomposite, namely, biocompatibility, bioactivity, biodegradability and osteoconductivity. The morphological characteristics, granule size and chemical composition, were indeed found to be favorable for osseous cell development. This study likewise showed lower mortality for the variant with weight ratio (40%CPC–60%PHBV). Conclusion: An in vivo investigation revealed that the new biomaterial composed of CPC and PHBV exhibits manifest osteoconductivity and bioactivity with better degradation kinetics than the CPC. Moreover, the variant with 40%CPC/60%PHBV appeared more resistant to infection than the 60%CPC/40%PHBV which is an indicator of biocompatibility.

The performance of the porous glass ceramic doped with 10 wt% Zinc and 2 wt% TiN (46S6-10Zn), in the restoration of critical diaphyseal bone defect, was evaluated by several physicochemical methods and histological studies. The critical defect in rabbits was created and then filled with 46S6-10Zn. At different periods after implementation, animals were sacrificed. Samples were harvested for exploration. The nuclear magnetic resonance (MAS-NMR) of 31 P and 29 Si illustrates the progressive degradation of 46S6-10Zn in favor to of the formation and the development of biological apatite. Therefore, after one month of implementation, MAS-NMR 29 Si proves the presence of Q 2 (25%), Q 3 (73%) and Q 4 (2%). However, after six months, the disappearance of all these species was revealed and characterized by the 46S6-10Zn dissolution. Besides, MAS-NMR 31 P demonstrates the presence of Q C 0 (4%), Q HA 0 (55%) and Q a 0 (41%) after one month. Nevertheless, six months later, we observe the presence of Q HA 0 (80%) and Q a 0 (20%). Histological study demonstrates an intimate contact of 46S6-10Zn surrounding bone after one month of implantation. However, after four months, mature bone matrix became calcified and the implanted 46S6-10Zn began to be degraded. Moreover, nine months later, 46S6-10Zn was nearly resorbed and replaced by a calcified tissue in the periphery and an osteoid tissue in the middle of bone defects.

International audience; Mesenchymal stem cells (MSCs) have been the subject of many studies in recent years, ranging from basic science that looks into MSCs properties to studies that aim for developing bioengineered tissues and organs. Adult bone marrow-derived mesenchymal stem cells (BM-MSCs) have been the focus of most studies due to the inherent potential of these cells to differentiate into various cell types. Although, the discovery of induced pluripotent stem cells (iPSCs) represents a paradigm shift in our understanding of cellular differentiation. These cells are another attractive stem cell source because of their ability to be reprogramed, allowing the generation of multiple cell types from a single cell. This paper briefly covers various types of stem cell sources that have been used for tissue engineering applications, with a focus on bone regeneration. Then, an overview of some recent studies making use of MSC-seeded 3D scaffold systems for bone tissue engineering has been presented. The emphasis has been placed on the reported scaffold properties that tend to improve MSCs adhesion, proliferation, and osteogenic differentiation outcomes

International audience; The aim of the current work is to study the physicochemical interactions between bisphosphonates molecules, risedronate (RIS) and bioactive glass (46S6) after their association by adsorption phenomenon. To more understand the interaction processes of RIS with the 46S6 surface we have used complementary physicochemical techniques such as Infrared (FTIR), RAMAN and nuclear magnetic resonance (NMR) spectroscopy. The obtained results suggest that risedronate adsorption corresponds to an ion substitution reaction with silicon ions occurring at the bioactive glass surface. Thus, a pure bioactive glass was synthesized and fully characterized comparing the solids after adsorption (46S6-XRIS obtained after the interaction of 46S6 and X% risedronate). Therefore, based on the spectroscopic results FTIR, RMAN and MAS-NMR, it can be concluded that strong interactions have been established between RIS ions and 46S6 surface. In fact, FTIR and RAMAN spectroscopy illustrate the fixation of risedronate on the bioactive glass surface by the appearance of several bands characterizing risedrontre. The 31P MAS-NMR of the composite 46S6-XRIS show the presence of two species at a chemical shift of 15 and 19 ppm demonstrating thus the fixation of the RIS on 46S6 surface.

Heat capacity measurements have been conducted by means of DSC on both crystalline and glassy lithium metaphosphate, from room temperature up to the melting region. The heat capacity of the glass is slightly higher than that of the crystal. Contrary to the crystal, in the neighborhood of T g, C p increases rapidly by 10 J mol−1 K−1 conferring to this glass a “fragile character.” Nevertheless, the passage through T m does not show any discontinuity and the values of the glass and of the crystal are identical. The Debye model appears to be realistic to describe the glass heat capacity to temperature dependence. The Debye temperature and frequency were determined by minimizing the R p and χ 2 parameters of the C v fitting curve. From the calculation of the entropy of the liquid at T > T m, the excess entropy of the glass at T g was determined. Using the dependence of the glass transition on the heating rate, we calculated the values of the activation energy for structural relaxation (E relax) and of the lower limit of the glass transition temperature ( $$ {T_{\text{g}}^{{^\circ }} } $$ ) which is a thermodynamic parameter, contrary to T g which is a kinetic parameter.

International audience; Chitosan scaffolds, combined with bioactive glass 46S6, were prepared to serve as gentamicin sulfate delivery in situ systems for bone biomaterials. This work presents a study about the effect of the ratio chitosan/bioactive glass (CH/BG) on the release of gentamicin sulfate and on the bioactivity during in vitro experiments. SEM observations allowed understanding the bond between the glass grains and the chitosan matrix. In vitro results showed that scaffolds form a hydroxyapatite (HA) Ca10(PO4)6(OH)2 after 15 days of immersion in a simulated body fluid (SBF).The interest of this study is to see that the increase of the content of bioactive glass in the chitosan matrix slows the release of gentamicin sulfate in the liquid medium. Starting concentration of gentamicin sulfate has an influence on the relaxation time of the scaffolds. Indeed, an increasing concentration delays the return to a new equilibrium. Contents of chitosan and bioactive glass do not affect the relaxation time. Synthesized scaffolds could be adapted to a clinical situation: severity and type of infection, weight and age of the patient.

Bioactive glasses belong to the ceramic family. They are good materials for implantation due to their excellent capacities to create an intimate bond with bones. Copper is known for its anti-inflammatory, antibacterial, and antifungal properties. Titanium is biocompatible and resistant to corrosion. These chemical elements can be introduced in bioactive glasses to provide a wide variety of uses and to enhance the physiological properties of implanted biomaterials. In this work, bioactive glasses doped with different contents of copper and titanium were synthesized by the melting method. The purpose is to study the effect of doping metal element on the thermal characteristics (T g, T c, and T f). The results revealed that the increase of the content of copper and titanium in the glass matrix decreases the melting temperature and induces an increase of the thermal stability. The excess entropies of pure and doped glasses were calculated. Obtained results highlighted the decrease of the excess entropy with the increase of metal elements contents.

International audience; The purpose of this paper is to explore the effect of titanium and silver on the characteristic temperatures of 46S6 glass and the excess entropy. The results show that the adding of these metals in the chemical composition does not affect the amorphous character of glasses. The introduction of these elements greatly reduces the melting temperatures of glasses and involves similar variations on the crystallization and glass transition temperatures. These elements also increase the thermal stability of glasses. The excess entropy calculations show a decrease when the content of Ti or Ag increases. Contrary to crystals, synthesized glasses have entropy different to zero at T = 0 K.

The main objective of the present work was to investigate the effect of surfactant type and synthesis temperature on the structure, porosity and the bioactivity of 92S6 (92% SiO2, 6% CaO, and 2% P2O5 mol %) mesoporous sol-gel glasses. The aim was to provide a basis for controlling the bioactive behavior of the different 92S6 samples used for tissue regeneration and for biomedical engineering in order to obtain sufficient performances by controlling the porosity of the glass. In this paper, a series of mesoporous bioactive glasses were synthesized using three different surfactants (C10H20BrN, C19H42BrN, C22H48BrN) at different aging temperatures (20°C, 40°C and 60°C). The surfactant was removed by calcination, which was carried out by increasing the temperature to 650°C for 6 h. A comparison among these synthesized glasses was conducted and the research emphasis was placed on the synthesis temperature and the surfactant type dependence on the textural properties and particularly porosity that were ultimately responsible for glass bioactivity.

A 92S6 glass with a composition in the ternary system SiO 2 –CaO–P 2 O 5 was prepared by sol–gel method. Material was synthesized at temperatures ranging from 20 to 60 °C for 24 h using C 16 TMABr (C 19 H 42 BrN) as surfactant. Then properties of these synthesized glasses were investigated. The structure, morphology and textural properties were studied by means of X-ray powder diffraction (XRD), analysis of nitrogen adsorption/desorption isotherms (BET and BJH methods), and by scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS). In vitro glasses bioactivity was evaluated by soaking them in simulated body fluid. The resulting solutions were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES). Results indicate that bioactivity increased with synthesis temperature. This result is principally related to differences in textural properties.

Bone loss associated with skeletal trauma or metabolic diseases often requires bone grafting. In such situations, a biomaterial is necessary for migrated cells to produce new tissue. In this study, agarose–chitosan was implanted in the femoral condyle of New Zealand White rabbits that were divided into three groups: Group I was used as control; Groups II and III were used as implanted tissue with agarose–chitosan and presenting empty defects, respectively. This study evaluated the agarose–chitosan biocompatibility by determining the in vivo genotoxicity, oxidative stress balance that correlated with the hardness mechanical property. Moreover, the histopathological and quantitative elements analyzed by using inductively coupled plasma optical emission spectrometry were determined. After 30 days of implantation, the in vivo analysis of genotoxicity showed that agarose–chitosan did not induce chromosome aberration or micronucleus damage. A significant decrease in thiobarbituric and acid-reactive substance was observed after agarose–chitosan implantation in the bone tissue. Superoxide dismutase, catalase and glutathione peroxidase were significantly enhanced in agarose–chitosan–treated group compared with that of control group. A negative correlation coefficient of the mechanical property with malonyldialdehyde level was detected (R = −0.998). The histological study exhibited a significantly increased angiogenesis and newly formed tissue. No presence of inflammatory process, necrotic or fibrous tissue was detected. Major and trace elements such as Ca, P, Zn, Mg and Fe were increased significantly in the newly formed bone. These findings show that agarose–chitosan biomaterial implantation might be effective for treating trauma and bone regeneration.

In this study, a mesoporous bioactive glass 92S6 (92% SiO 2 , 6% CaO, and 2% P 2 O 5 ), was successfully prepared using two different surfactants. The template was further removed by calcination to generate unorganized or well-ordered pores. The bioactive glass was characterized by wide angle X-ray diffraction (WAXRD) analysis, small angle X-ray diffraction (SAXRD) analysis, Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). From the isotherm desorption branch, the surface area was determined using the Brunauer–Emmett–Teller (BET) method, while pore volume and pore size distribution were determined by the Barrett–Joyner–Halenda (BJH) method. The in vitro bioactivity tests were also conducted in simulated body fluid (SBF). Finally, the samples were analyzed to quantify the apatite formation ability when soaked in SBF solution. The evolutions of silicon (Si), phosphorus (P) and calcium (Ca) concentrations in SBF were evaluated by inductively coupled plasma optical emission spectrometry (ICP-OES). The SAXRD and TEM studies evidence the influence of the structure-directing agent (ionic surfactant CTAB or non-ionic P123) in the generation of unorganized or well ordered pores in the sol–gel synthesis of a bioactive glass in the ternary system SiO 2 –CaO–P 2 O 5 . As observed from small-angle XRD patterns and TEM images, the presence of non-ionic surfactant and subsequent calcination lead to the formation of highly ordered mesoporous glass. The better textural properties observed in the “ordered mesoporous glasses” compared to those of “non-ordered mesoporous glasses” lead to a faster in vitro bioactivity kinetics.

Chitosan (CH) material reinforced by bioactive glass (46S6) was fabricated. 46S6 containing 17% wt% CH was studied in vitro and in vivo. Physicochemical techniques, such as Fourier transform infrared spectroscopy (FT-IR), coupled plasma optical emission spectrometry (ICP-OES) analysis were used. The behavior of 46S6CH17 was studied by measuring the in situ pH in a SBF solution. The 46S6CH17 was implanted in the rat femoral condyl. In vitro 46S6CH17 gave an FTIR - spectrum in which three absorption bands with the maxima at 565, 603 and 1039cm-1 after 3 days of soaking in physiological solution. They are assigned to stretching vibrations of PO4^3- group in phosphate crystalline. Moreover, the pH measurement was decreased in the SBF solution. The stability of the calcium phosphate precipitation depended on the pH value. In vivo, a rise in the Ca and phosphate P ions concentrations in the implanted microenvironment was determined., {"references":["R.A. Muzzarelli, F. Tanfani, M. 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International audience; Scaffolds are implants used to deliver cells, drugs, and genes into the body in a local controlled release pattern which offers many advantages over systematic drug delivery. Composite scaffolds of polyvinyl alcohol (PVA) and quaternary bioactive glass (46S6 system) with different ratios of glass contents were prepared by the lyophilisation technique. The broad spectrum antibiotic ciprofloxacin (Cip) was impregnated to the scaffold during the fabrication in a concentration of 5, 10 and 20%. Biodegradation rate and in-vitro mineralization of the prepared scaffolds were performed by soaking the scaffolds in simulated body fluid (SBF). Phase identification, microstructure, porosity, bioactivity, mechanical properties and drug release pattern in PBS were characterized by XRD, SEM coupled with EDS, Hg-porosimeter, inductively coupled plasma-optical emission spectroscopy (ICP-OES), universal testing machine, fourier transform infrared (FTIR) and UV-spectrophotometer, respectively. A porous scaffold has been obtained with porosity up to 85%. By increasing the glass contents in the prepared scaffold the porosity and the degradation rate decrease however, the compressive strength was enhanced. A sustained drug release pattern was observed with a quasi-Fickian diffusion mechanism. The formulated ciprofloxacin loaded porous polyvinyl alcohol scaffold gave an acceptable physicochemical properties and was able to deliver the drug in a prolonged release pattern which offers a distinguish treatment for osteomylitis as well as local antibacterial effect.

Bioactive glass 46S6 and biodegradable therapeutic polymer (Chitosan: CH) have been elaborated to form 46S6-CH composite by freeze-drying process. The kinetics of chemical reactivity and bioactivity at the surface were investigated by using physicochemical techniques, particularly solid-state MAS-NMR. Immortalized cell line used to construct multicellular spheroids was employed as three-dimensional (3D) cell cultures for in vitro studies. Obtained results showed a novel structure of the composite; the chemical treatment (ultrasound, magnetic stirring, freeze drying process and lyophilization) led the bioactive glass particles to be loaded in the chitosan-based materials. 29Si and 31P MAS-NMR results showed the emergence of two new species, Q 3 (OH) and Q 4 , which are characteristic of the vitreous network dissolution in simulated body fluid (SBF). MAS-NMR also confirmed the formation of amorphous calcium phosphate (ACP) at the surface of the initial 46S6-CH. Three-dimensional (3D) cell cultures highlighted the effect of chitosan, where the cell viability reached up to 78% in 46S6-CH composite and up to 67% in 46S6. The association of (CH) and bioactive glass (BG) matrix promotes a highly significant bioactivity, demonstrating surface bone formation and satisfactory behavior in biological environment.

The authors declare that they have no conflicts of interest concerning this article.; International audience; New synthetic biomaterials are constantly being developed for wound repair and regeneration. Bioactive glasses (BG) containing strontium have shown successful applications in tissue engineering account of their biocompatibility and the positive biological effects after implantation. This study aimed to assess whether BG-Sr was accepted by the host tissue and to characterize oxidative stress biomarker and antioxidant enzyme profiles during muscle and skin healing. Wistar rats were divided into five groups (six animals per group): the group (I) was used as negative control (T), after ovariectomy, groups II, III, IV and V were used respectively as positive control (OVX), implanted tissue with BG (OVX-BG), BG-Sr (OVX-BG-Sr) and presented empty defects (OVX-NI). Soft tissues surrounding biomaterials were used to estimate superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and malondialdehyde (MDA) concentration. Our results show that 60 days after operation, treatment of rats with BG-Sr significantly increased MDA concentration and caused an increase of SOD, CAT and GPx activities in both skin and muscular tissues. BG-Sr revealed maturation of myotubes followed a normal appearance of muscle regenerated with high density and mature capillary vessels. High wound recovery with complete re-epithelialization and regeneration of skin was observed. The results demonstrate that the protective action against reactive oxygen species (ROS) was clearly observed in soft tissue surrounding BG-Sr. Moreover, the potential use of BG-Sr rapidly restores the wound skin and muscle structural and functional properties. The BG advantages such as ion release might make BG-Sr an effective biomaterial choice for antioxidative activity.

A new composition of bioactive glass, in the quaternary system SiO 2 –CaO–Na 2 O–P 2 O 5 , was synthesized using melting and sol–gel routes. The prepared glass, 52S4: (wt.%) 52% SiO 2 –30% CaO–14% Na 2 O–4% P 2 O 5 , was soaked in Simulated Body Fluid (SBF) in order to evaluate the kinetic reactivity of this glass versus the synthesis mode. The obtained results have shown that 52S4 is a bioactive glass if it is prepared either by melting or sol–gel methods. The bone-like apatite was formed at the glass surface prepared by sol–gel route after 2 h. However, the formation of this apatite was delayed to 1 day when the glass was prepared by melting method. In addition, this apatite was crystallized, after 30 days soaking in SBF, only if the glass is prepared by melting route. The glass prepared by sol–gel method was more resorbable and leads to silica gel formation up on amorphous apatite layers at any time. So, this silica gel inhibited the crystallization of amorphous apatite.

International audience; Bioactive glasses prepared in SiO2-CaO-Na2O and P2O5 system are used as biomaterials in orthopaedic and maxillofacial surgery. Zn presents high physiological interest. It enhances physiological effects of implanted biomaterials. In this work, the thermal characteristics (Tg, Tc and Tf) of pure bioactive glass elaborated with different amounts of CaO, Na2O in pure glass and with different amounts of introduced Zn in glass (ranging from 0.1 to 10 in wt%), were studied. The excess entropy was calculated for different compounds. Glasses were prepared by the melting process. The thermal behaviour of obtained bioactive glasses was determined using differential thermal analysis. Therefore, the glass transition (Tg), the crystallization (Tc) and the melting temperatures (Tf) were revealed. Moreover, according to Dietzel formula, the thermal stability (TS) of the studied bioactive glasses has been calculated. The first results concerning the impact of different oxides, revealed a decrease of the TS, Tg, Tc and Tf when the SiO2/CaO increases and revealed an increase of these thermal characteristics when the SiO2/Na2O and CaO/Na2O ratios increase. Introducing Zn into the bioactive glasses induces a decrease of Tf and an increase of TS. Contrary to crystals, prepared glasses have entropy different to zero at T = 0 K and vary versus Tf. The excess entropy of pure glasses and Zn-doped glasses were calculated. The significant variations were registered.

Osteoinductive and antiosteroporotic phenomena could be created by using synthetic biomaterials for applications in bone surgery. In the present study, CH-based bioactive glass (BG-CH) with 17 wt% chitosan was elaborated by a freeze-drying process. BG-CH was implanted in the muscle and in the femoral condyles of ovariectomised rats. Grafted tissues were carefully removed for physico-chemical and histological analysis. Several physic-chemical techniques (XRD, FT-IR, MEB, ICP-OES and NMR) were employed to highlight the effects of chitosan on the glass matrix before and after implantation. The results of the study show that despite the non-additional osteogenic cells or agents, BG-CH is endowed with an osteoinductive property. After 8 weeks, 13C NMR spectra showed the characteristic signals of γ-carbons of the hydroxyproline (71 ppm) abundant in collagen. γ-carboxyglutamate (55 ppm), which occurs in several other bone proteins like osteocalcin, indicating the BGCH degradation and the dominance of the bone tissue formation. Moreover, this study showed a rise in Ca and P ion concentrations in the implanted microenvironment, leading to the formation/deposition of Ca-P phases. Trace elements such as Zn and Fe were detected in the newly-formed bone and involved in the bone healing. The study highlights the suitability and the extensive applications of BG-CH composites and the clinically useful therapy in regenerative medicine.

Strontium (Sr) compounds have become increasingly popular in the field of osteoporosis treatment. However, the quality of new bone after implantation of strontium-containing bioceramics has yet to be investigated. In the present study, the newly formed bone tissue around strontium-doped bioactive glass (BG-Sr) implants was characterized. BG-Sr was implanted in the femoral condyl of ovariectomised rats (OVX). The resected bone was prepared for analysis using several physico-chemical and biological assays such as Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, and histomorphometry. BG-Sr biomaterial favored calcium phosphate layer integration on the surface of the glass and offered better bioactivity. Moreover, the histomorphometric analysis demonstrated that BV/TV, N. Ob were significantly higher in BG-Sr treated rats groups than those of BG groups. However, Ob. S/BS, and OV/BV were significantly lower in BG-Sr treated rats groups than those of BG groups. The (Oc.S/BS) was significantly decreased in BG-Sr groups, when compared with that of BG rat groups. On the other hand, the MS/BS had not significantly decreased in the BG-Sr treated rats groups when compared with that of BG groups, however; it was significantly higher when compared with control and OVX groups. These findings suggest that BG-Sr can be used as an inhibitory therapeutic potential of osteoporosis by delivering strontium to stimulate new bone remodeling.

International audience; Orthopedic devices are used in pathologic disorder as an adjunct to bone grafts to provide immediate structural stability. Unfortunately, the use of metallic devices has some complications. This study aimed to characterize the oxidative stress biomarker and the antioxidant enzyme profiles during bone regeneration. New Zealand White rabbits were divided into 4 groups: Group (I) was used as control (T), Groups II, III, and IV were used, respectively, as implanted tissue with carbonated hydroxyapatite (CHA), carbonated hydroxyapatite associated with external fixator (CHA + EF), and presenting empty defects (ED). Grafted bone tissues were carefully removed to measure malondialdehyde (MDA) concentration, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase activities (GPx). Our results showed that 4 weeks after operation, treatment of rabbits with CHA + EF showed a significantly higher malondialdehyde (MDA) concentration when compared to that of control group. The SOD, CAT, and GPx in CHA + EF group showed significantly lower activities when compared to those in control group. Eight weeks after surgery, the CHA + EF group presented a lower concentration of MDA as compared to those seen after the first 4 weeks after surgery. On the other hand, the SOD, CAT, and GPx showed a higher activity when compared with the same group. Consequently, MDA concentration and the antioxidant enzyme activities were not significant (p > 0.05) when compared to those in control group rabbits. Histologic sampling has demonstrated successful time-patterned resorption accompanied by bone replacement and remodeling. These results suggest that there was a temporary increase in the oxidative marker level in CHA + EF healing bone and the 8-week period was sufficient to re-establish oxidant-antioxidant balance accompanied by bone repair in the tibia rabbit model.

International audience; In this study, the ability to form bone-like apatite on surface of both pure natural hydroxapatite (N-HA) and natural hydroxyapatite containing 5 wt% of ZrO2 or TiO2 or Al2O3, sintered at 1300°C for 2 h and soaked in the simulated body fluid for different times, was studied. It has been found that the presence of β-tricalcium phosphate in N-HA + 5 wt% ZrO2 or TiO2 has promoted the precipitation of bone-like apatite in the Zr or Ti poorest regions. By contrast, the presence of 5 wt% of Al2O3 did not induce any apatite precipitation on N-HA sample surfaces.

Bone loss associated with skeletal trauma or metabolic diseases often require bone grafting. The present study aimed to evaluate the performance of bioactive glass-chitosan composite (BG-CH) produced by a freeze-drying process. BG containing 17% wt% CH was implanted in the femoral condyl of an ovariectomised rat. The resected bone was prepared for analysis using several physico-chemical techniques such as fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX). After 2 weeks, the implanted sample gave a spectrum in which two pronounced absorption bands with the maxima at 932 and 1036 cm-1 arising from (Si-O-Si) groups disappeared 15 days after surgery. These bands were replaced 30 days after implantation by 601 and 564 cm-1(P- O) arisen form bone apatite bands. After 4 weeks, peaks at 31.6 and 25.8° (2θ) were registered thus inducing a degradation of BG-CH which occurred simultaneously with the implant replacement by the bone cells. Our data showed that the incorporation of 17% wt% CH with BG matrix promoted a highly significant bioactivity and generated an osteoinductive property. These effects might make BG-CH an effective biomaterials choice for the biomedical field. Key words: Chitosan-glasses, biominiralisation, osteoinductivity, biomedical applications, bone defect healing.

International audience; Biocomposite of bioactive glass (BG) with chitosan polymer (CH) is prepared by freeze-drying technique. Obtained material is investigated by using several physico-chemical methods. The XRD and FTIR show the interface bonding interactions between glass and polymer. The specific surface and porosity of biocomposite were determined. In vitro assays were employed to evaluate the effect of chitosan addition on the glass by studying the chemical reactivity and bioactivity of the BG and BG/CH biocomposite after soaking in a simulated body fluid (SBF). The obtained results show the formation of a bioactive hydroxycarbonate apatite (HCA) layer and highlight the bioactivity and the kinetics of chemical reactivity of bioactive glass, particularly after association with chitosan. The BG/CH biocomposite has excellent ability to form an apatite layer. Inductively coupled plasma-optical emission spectrometry (ICP-OES) highlights the negative effect of chitosan on the silicon release toward the SBF of bioactive glass when in vitro assays.

International audience; Titanium alloys used in orthopedic surgery are usually coated with hydroxyapatite to improve their biocompatibility and osseointegration. Bioactive glasses (BGs) are an interesting alternative to hydroxyapatite for the production of prosthetic coatings due to their osteoproductive property (Class A bioactivity) and to their resorbability. However the classical techniques used to obtain prosthetic coatings are not suitable in the case of BGs. In this study bioactive glass coatings are obtained by electrophoretic deposition on a Ti12Mo5Ta alloy. These coatings were obtained from ethanol suspensions of two different bioglass powders: a Sol-Gel derived 58S and a Melting-Quenching derived 46S. Scanning electron microscopy observations were used to characterize the coatings (morphology and thickness) and the coating/substrate interfaces. The chemical composition of the coatings was studied by X-ray microanalysis and X-ray maps were performed to characterize the spatial distributions of all elements composing the coatings.

International audience; Bioactivity and chemical reactivity of bioactive glass offer the ability to bond for soft and hard biological tissues. In this work, synthesis was carried out by using melting and rapid quenching. Strontium was introduced as trace element at different contents in the glass matrix, according to its concentration in the bone matrix. This chemical element presents a high interest in the bone metabolism activity. Investigations were conducted on the surface of biomaterials by using in vitro assay after immersion in SBF. Several physico-chemical methods such as SEM, FTIR, NMR, ICP-OES and MTT test were employed to highlight the effects of the Sr. The in vitro experiments showed that after soaking in SBF, the behaviour of pure glass is different compared to glass doped with Sr. NMR analyses showed in the 29Si MAS-NMR that glass matrix undergoes some changes after in vitro assays particularly the emergence of new components attributed to Q3(OH). The presence of Sr slowed down the bioactivity of glass after immersion in SBF. The non toxic character of compounds was confirmed. Introduction of Sr at 0.1 wt % induce an enhancement of cells at about 14.3%.

International audience; The use of bone grafts permits the filling of a bone defect without risk of virus transmission. In this work, pure bioactive glass (46S6) and zinc-doped bioactive glass (46S6Zn10) with 0.1 wt% zinc are used to elaborate highly bioactive materials by melting and rapid quenching. Cylinders of both types of glasses were soaked in a simulated body fluid (SBF) solution with the aim of determining the effect of zinc addition as a trace element on the chemical reactivity and bioactivity of glass. Several physico-chemical characterization methods such as x-ray diffraction, Fourier transform infrared spectroscopy and nuclear magnetic resonance methods, with particular focus on the latter, were chosen to investigate the fine structural behaviour of pure and Zn-doped bioactive glasses as a function of the soaking time of immersion in SBF. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) was used to measure the concentrations of Ca and P ions in the SBF solution after different durations of immersion. The effect of the investigated samples on the proliferation rate of human osteoblast cells was assessed by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, and tested on two different sizes of pure and zinc-doped glasses in powder form, with particle sizes that ranged between 40 to 63 µm and 500 to 600 µm. The obtained results showed the delay release of ions by Zn-doped glass (46S6Zn10) and the slower CaP deposition. Cytotoxicity and cell viability were affected by the particle size of the glass. The release rate of ions was found to influence the cell viability.

International audience; Metal nanoparticles play an important role in many different areas such as catalysis, electronics, sensors, and cancer therapy. Silver, in its many oxidn. states (Ag0, Ag+, Ag2+, and Ag3+), has long been recognized as having an inhibitory effect towards many bacterial strains and microorganisms commonly present in medical and industrial processes. Silver was introduced in various materials including hydroxyapatite due to its biocompatibility. The unique size-dependent properties of nanomaterials make them superior and indispensable. In this work, nanohydroxyapatite/polyvinylpyrrolidone composite was doped with 2 different concns. of silver nanoparticles prepd. by redn. method. Several techniques like TEM, XRD, FT-IR, and SEM with EDS were used to characterize the prepd. samples. The bioactivity test (soaking in SBF) at different short time intervals was characterized by using inductively coupled plasma-optical emission spectroscopy (ICP-OES) method. It is demonstrated that silver-doped nanohydroxyapatite obviously improves the bioactivity of the apatite at the early stages of immersion. The antibacterial inhibition over 3 types of bacteria (Staphylococcus aureus, Streptococcus mutans, and Pseudomonas) is under investigation.

International audience; Many types of bone substitutes exist to fill a bony defect. They must be compatible and bond with the host tissue without any formation of fibrous capsule. The direct apposition of bone to bioactive materials, including bioactive glasses and calcium phosphates, has already been demonstrated. In this work, different compns. of bioactive glasses elaborated by melting and rapid quenching were studied. They were based on SiO2-CaO-Na2O and P2O5. Several physicochem. methods like XRD, FTIR, SEM and ICP-OES were employed to characterize all bioactive glasses. They were investigated as bony biomaterials using "in vitro" assays. The aim was to evaluate their chem. reactivity and their bioactivity after soaking in simulated body fluid (SBF). [on SciFinder(R)]

International audience; OBJECTIVES: Nanoparticles from implanted materials are reported as the main cause of implant failure. Monocytes are among the first cells to colonize the inflammatory site. We evaluated the biological effects of bone substitutes presented to U937 cells in vitro as micron- or nanometer-sized particles. METHODS: The HA (550 nm) and beta-TCP (550 nm) nanoparticles were incubated with U937 cells. Cell cycle modification, specific antigens expression, and the extent of cell death were determined. RESULTS: Firstly, by using the sulforhodamine B (SRB) test and the annexin V-FITC analysis by flow cytometry, our results provide evidence of the absence of cytotoxicity, and show that nanoparticles do not induce more apoptosis than microparticles in U937 cells. Secondly, although morphologic evidence of stimulation of U937-cells was found by confocal microscopy, neither bone substitute altered the distribution of the cells into different phases of the cell cycle (Kit Cycle Test Plus DNA). These results suggest that nanoparticles do not cause promonocyte maturation in macrophages. Thirdly, the flow cytometry results showed no differences in the expression of the adherence and activation markers. SIGNIFICANCE: The results suggest that nanoparticles do not promote the differentiation of promonocytic U937 cells into macrophages and do not induce an enhanced inflammatory response.

International audience; Two series of tin containing molybdophosphate and tungstophosphate glasses and glass-ceramics were achieved by means of a domestic microwave oven under air. During melting, a redox reaction takes place between Sn2+ and Mo6+ generating the crystallization of a Na(SnIV,MoIV)(PO4)3 solid solution with a NZP (NaZr2P3O12) type structure. Such reactivity was not underlined in the case of the W-series. All the samples were characterized from a thermal and mechanical point of view as a function of the RO3 (R = Mo, W) for SnO substitution. Two types of behaviors were identified. For the Mo-series, all the characteristics, except density, present an extremum value for the chemical composition with a 1:1 SnO-MoO3 molar ratio. This is strongly correlated to the amount of NZP crystals present in the glass ceramic, the different behavior observed for the density being due to the low compactness of the NZP phase. For the W-series, all these different characteristics varies monotonously according to a progressive strengthening of the network by replacement of a low field strength ion (Sn2+) by a higher field strength ion (W6+). In addition, the solid state reactivity of a 1:1 SnO-RO3 mixture was examined confirming the absence of any redox process between SnO and WO3 during the glass synthesis.

International audience; The control of the in vitro and in vivo bioactivity, as well as the chemical reactivity of melt-derived glasses is an important state in the biomaterials field. The present work explores the local structure of bioactive glasses before and after in vitro assays in simulated body fluid. This study by solid-state MAS-NMR constitutes an original approach to the understanding of the bioactivity process.

The dissolution kinetic and structural behaviour of natural hydroxyapatite (N-HA) and synthetic hydroxyapatite (S-HA) was studied vs. sintering temperature and using ‘in vitro’ experiments. Obtained results highlight the chemical stability of N-HA. Any structural modification was observed until 1200°C. In the fact S-HA undergoes some modifications. XRD diagrams show the tricalcium phosphate (TCP) phase formation between 800 and 1100°C and tetracalcium phosphate (TetCP) phase formation at 1200°C. The ‘in vitro’ assay shows that the dissolution was occurred more in N-HA than in S-HA. The formed TCP activated the dissolution kinetic and then the precipitation phenomena when a continuous dissolution of TetCP leaded to slow down the kinetic precipitation.

International audience; Synthetic aragonite-based porous materials were drug loaded with gentamicin sulphate, an antibiotic active on Staphylococcus aureus responsible for osteomyelitis. Drug loading was accomplished by two different ways: by integration of gentamicin in material during processing or by soaking material into gentamicin solutions. We first investigated the influence of drug loading on compressive strength of materials. Results indicate that soaked materials presented the same compressive strength than unloaded materials with the same porosity. By contrast, the integration of gentamicin during processing increased significantly the compressive strength of materials. The materials drug content before elution was a least 10 times higher when gentamicin was integrated during processing comparatively to soaked materials. The study of in vitro gentamicin release showed that for materials with gentamicin integrated during material processing, high concentrations of gentamicin were released up to 8 or 12 days, against 4 days for soaked materials. The transport coefficients calculation, for the first step of release, indicated that the rate of release was higher for materials with integrated gentamicin because of the higher gentamicin content. The porosity rate influenced the rate of release for materials positively with gentamicin integrated during processing contrary to soaked materials for which a higher porosity rate allowed a deeper penetration of gentamicin during drug loading and then a slightly slower release. Results indicate that aragonite-based material with gentamicin integrated during material processing may be used either as resorbable device for release of high concentrations of gentamicin or as biomaterial for combined therapy: bone substitution and prevention or treatment of osteomyelitis. (c) 2005 Wiley Periodicals. Inc.