Bioactivity of toothpaste containing bioactive glass in remineralizing media: effect of fluoride release from the enzymatic cleavage of monofluorophosphate

Objectives. The aim was to introduce a new methodology to characterize toothpaste containing bioactive glass and to evaluate the effect of release of fluoride ions, by cleaving monofluorophosphate (MFP), on the mineral forming ability of Sensodyne Repair & Protect (SRP). which contains NovaMinTM (bioactive glass, 45S5 composition). Methods. SRP, NovaMin particles, and placebo paste (PLA) which did not contain NovaMin, were immersed into a remineralization media (RS), which mimics the ionic strength of human saliva, for 3 days with different concentrations of alkaline phosphatase (ALP): 0, 25 and 75 U.L−1. Ion concentration profiles and pH were monitored by ICPOES and F− ion selective electrode. Remaining solids were collected by freeze-drying and their surfaces analysed. Results. Hydroxyapatite (HA) formed on the surface of BG alone (after 1 h) and in toothpaste (after 2 h), whereas PLA did not induce any precipitation. ALP cleaved MFP at different rates depending on the enzyme concentration. Increasing the concentration of ALP from 0 and 75 U.L−1 reduced the time of HA formation from 2 h to 24 h. However, the presence of fluoride induced the precipitation of fluorapatite. No evidence of fluorite (CaF2) was observed. The apatite formation ability of toothpaste can be assessed using the presented method

Morthomiers – Les Crias

Le diagnostic d’archéologie préventive réalisé préalablement à un projet de création d’un lotissement, au lieu-dit les Crias à Morthomiers (Cher) porte sur une surface de 47 703 m2. L’emprise prescrite apparaît sur le versant méridional d’un thalweg formé par le cours d’eau intermittent la Margelle et s’étend au sud-est du cœur de village de Morthomiers, dans un secteur en voie d’urbanisation gagnant sur les terres agricoles. Les vestiges archéologiques recensés aux proches abords de l’empris..

Bourges – Cour Mauduit, boulevard de Chanzy

Le diagnostic réalisé préalablement à un projet de construction d’un bâtiment, à l’angle du boulevard de Chanzy et du Cour-Mauduit à Bourges, parcelle HX 332 (site no 18 033 669), porte sur une surface de 498 m2. La stratigraphie observée est épaisse, mais relativement peu complexe. Elle peut être divisée en sept grandes séquences stratigraphiques dont les six dernières couvrent une large période chronologique allant de l’Antiquité jusqu’à nos jours. Aucun indice d’anthropisation antérieur au..

Impact of the polymer design on the structure and properties of class II silicate hybrids

Many tissues have the fascinating ability to self-heal or remodel when experiencing stresses or trauma. However, above a critical defect size, our body cannot regenerate by itself leading to the formation of non-functional scar tissue. Biomaterials can be used to provide a temporary template for the damaged tissues, facilitating their full regeneration. However, the synthesis and use of such materials must adequately respond to the specific needs of the tissue targeted and therefore fulfil distinctive criteria. It is particularly true for the reconstruction of bone tissue, still lacking of an ideal synthetic biomaterials template. In this thesis, a biomimetic approach was developed to synthesise an ideal im- plant for the regeneration of hard tissues. A bottom-up strategy was used based on the sol-gel process where inorganic/organic hybrid co-networks were fabricated. To do so, bespoke polymers were synthesised containing alkoxysilane precursors which can be used to covalently bond to the growing silica network during the sol-gel process. A particular attention was brought to polymers with a high degree of cross-linking in particular homopolymers of 3-(trimethoxysilyl)propyl methacrylate and N- [3-(trimethoxysilyl)propyl] acrylamide. Models were developed and applied to experimental data to get a better insight on how these polymers affect the sol-gel process as well as the structure and properties of their resulting hybrids, as a function of the inorganic to organic ratio, molecular weight, polydispersity and synthesis methods. A good understanding of these materials is crucial to improve their properties, progressing towards an ideal implant. Hybrids were found to outperform their pure inorganic equivalent in terms of me- chanical properties, nucleation of bone like minerals, cell attachment and proliferation, presenting a huge potential for the regeneration of hard tissue.Open Acces

Ductile silica/methacrylate hybrids for bone regeneration

Bioglass® was the first synthetic material capable of bonding with bone without fibrous encapsulation, and fulfils some of the criteria of an ideal synthetic bone graft. However, it is brittle and toughness is required. Here, we investigated hybrids consisting of co-networks of high cross-linking density polymethacrylate and silica (class II hybrid) as a potential new generation of scaffold materials. Poly(3-(methoxysilyl)propyl methacrylate) (pTMSPMA) and tetraethyl orthosilicate (TEOS) were used as sol–gel precursors and hybrids were synthesised with different inorganic to organic ratios (Ih). The hybrids were nanoporous, with a modal pore diameter of 1 nm. At Ih = 50%, the release of silica was controlled by varying the molecular weight of pTMSPMA while retaining a specific surface area above 100 m2 g−1. Strain to failure increased to 14.2%, for Ih = 50% using a polymer of 30 kDa, compared to 4.5% for pure glass. The modulus of toughness (UT) increased from 0.73 (pure glass) to 2.64 GPa. Although, the hybrid synthesised in this report did not contain calcium, pTMSPMA/SiO2 hybrid was found to nucleate bone-like mineral on its surface after 1 week of immersion in simulated body fluid (SBF), whereas pure silica sol–gel glass did not. This increase in apatite forming ability was due to the ion–dipole complexation of calcium with the ester moieties of the polymer that were exposed after release of soluble silica from TEOS. No adverse cytotoxicity for MC3T3-E1 osteoblast-like cells was detected and improved cell attachment was observed, compared to a pure silica gel. pTMSPMA/SiO2 hybrids have potential for the regeneration of hard tissue as they overcome the major drawbacks of pure inorganic substrates while retaining cell attachment

Procédures curieuses de l'Inquisition de Portugal contre les Francs-Maçons. Pour découvrir leur Secret, avec les Interrogatoires & les Réponses, les Cruautés exercées par ce Tribunal, la description de l'intérieur du S. Office, son Origine, & ses Excès. Divise'es en Trois Parties

Portada a dos tintas, con símbolo masónico (escuadra)Fecha y lugar de publicación controvertidos: Georgi indica: Leipzig, 1746. Brit. Mus. Catal. consigna incluso 1756. También Kulcsár: Hamburg, 1756 ... [Van der Vekene I, 1735]Biblioteca Emil van der Vekene. - Van der Vekene I, 1735. #156#Sign.: *4, A-Q8, R4

A structural and physical study of sol–gel methacrylate–silica hybrids: intermolecular spacing dictates the mechanical properties

Sol–gel hybrids are inorganic/organic co-networks with nanoscale interactions between the components leading to unique synergistic mechanical properties, which can be tailored, via a selection of the organic moiety. Methacrylate based polymers present several benefits for class II hybrids (which exhibit formal covalent bonding between the networks) as they introduce great versatility and can be designed with a variety of chemical side-groups, structures and morphologies. In this study, the effect of high cross-linking density polymers on the structure–property relationships of hybrids generated using poly(3-trimethoxysilylpropyl methacrylate) (pTMSPMA) and tetraethyl orthosilicate (TEOS) was investigated. The complexity and fine scale of the co-network interactions requires the development of new analytical methods to understand how network evolution dictates the wide-ranging mechanical properties. Within this work we developed data manipulation techniques of acoustic-AFM and solid state NMR output that provide new approaches to understand the influence of the network structure on the macroscopic elasticity. The concentration of pTMSPMA in the silica sol affected the gelation time, ranging from 2 h for a hybrid made with 75 wt% inorganic with pTMSPMA at 2.5 kDa, to 1 minute for pTMSPMA with molecular weight of 30 kDa without any TEOS. A new mechanism of gelation was proposed based on the different morphologies derived by AC-AFM observations. We established that the volumetric density of bridging oxygen bonds is an important parameter in structure/property relationships in SiO2 hybrids and developed a method for determining it from solid state NMR data. The variation in the elasticity of pTMSPMA/SiO2 hybrids originated from pTMSPMA acting as a molecular spacer, thus decreasing the volumetric density of bridging oxygen bonds as the inorganic to organic ratio decreased

Hyaluronic acid hydrogels reinforced with laser spun bioactive glass micro- and nanofibres doped with lithium

The repair of articular cartilage lesions in weight-bearing joints remains as a significant challenge due to the low regenerative capacity of this tissue. Hydrogels are candidates to repair lesions as they have similar properties to cartilage extracellular matrix but they are unable to meet the mechanical and biological requirements for a successful outcome. Here, we reinforce hyaluronic acid (HA) hydrogels with 13-93-lithium bioactive glass micro- and nanofibres produced by laser spinning. The glass fibres are a reinforcement filler and a platform for the delivery of therapeutic lithium-ions. The elastic modulus of the composites is more than three times higher than in HA hydrogels. Modelling of the reinforcement corroborates the experimental results. ATDC5 chondrogenic cells seeded on the composites are viable and more proliferation occurs on the hydrogels containing fibres than in HA hydrogels alone. Furthermore, the chondrogenic behavior on HA constructs with fibres containing lithium is more marked than in hydrogels with no-lithium fibres.Xunta de Galicia | Ref. ED431B 2016/042Xunta de Galicia | Ref. POS-A/2013/161Xunta de Galicia | Ref. ED481D 2017/010Xunta de Galicia | Ref. ED481B 2016/047-

Dielectric spectroscopy and dissolution studies of bioactive glasses

The first and rate-limiting step in the degradation of bioactive glasses is thought to be the ion exchange of hydrated protons in the external fluid with alkali metal cations in the glass. The activation energy (Eₐ) for alkali ion hopping can be followed by dielectric spectroscopy. The replacement of CaO by Na₂O resulted in a reduction in the Eₐ for ion hopping. In contrast, increasing the glass network connectivity or reducing the nonbridging oxygen content of the glass resulted in an increase in Eₐ. Substitution of K₂O for Na₂O had little influence on Eₐ. Mixing alkali metals increased the Eₐ as expected on the basis of the mixed alkali effect. There was no correlation between the Eₐ for ion hopping and the dissolution behavior of the glass. Furthermore, the activation energy for Si, Ca Na, and K ion release was found to be approximately a factor of three lower than that for ion hopping suggesting that another rate-controlling mechanism is important in the degradation of bioactive glasses. The presence of a second relaxation process suggested that bioactive glasses undergo amorphous phase separation into silica-rich and orthophosphate-rich phases and the two relaxation processes are due to ion hopping in the two phases