MicroRNA-146a-loaded magnesium silicate nanospheres promote bone regeneration in an inflammatory microenvironment.

Reconstruction of irregular oral-maxillofacial bone defects with an inflammatory microenvironment remains a challenge, as chronic local inflammation can largely impair bone healing. Here, we used magnesium silicate nanospheres (MSNs) to load microRNA-146a-5p (miR-146a) to fabricate a nanobiomaterial, MSN+miR-146a, which showed synergistic promoting effects on the osteogenic differentiation of human dental pulp stem cells (hDPSCs). In addition, miR-146a exhibited an anti-inflammatory effect on mouse bone marrow-derived macrophages (BMMs) under lipopolysaccharide (LPS) stimulation by inhibiting the NF-κB pathway via targeting tumor necrosis factor receptor-associated factor 6 (TRAF6), and MSNs could simultaneously promote M2 polarization of BMMs. MiR-146a was also found to inhibit osteoclast formation. Finally, the dual osteogenic-promoting and immunoregulatory effects of MSN+miR-146a were further validated in a stimulated infected mouse mandibular bone defect model via delivery by a photocuring hydrogel. Collectively, the MSN+miR-146a complex revealed good potential in treating inflammatory irregular oral-maxillofacial bone defects.

Preparation, optimization, and characterization of chitosan-sepiolite nanocomposite films for wound healing.

In this study, a series of chitosan-sepiolite (CS-SEP) nanocomposites films were prepared by using a conventional solution casting method. The effect of sepiolite on physicochemical and biological properties of the prepared nanocomposite films was studied by various techniques such as Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and x-ray diffraction (XRD) to name a few. In WCA measurements, the decrease of contact angle from 78.51° (CS) to 71.29° (CS7SEP3) reaffirms the water holding nature of sepiolite, which enables to create moist environment essentially required for wound healing. Further, addition of sepiolite tremendously increased WVTR, folding endurance, porosity, and blood clotting ability of the prepared nanocomposites. Furthermore, CS-SEP nanocomposite films exhibit better antibacterial activity than that of chitosan against gram positive (B. subtilis) and gram negative bacteria (E. coli). Moreover, the percentage of hemolysis and degradation study indicated that the prepared nanocomposite films were non-hemolytic in nature and decomposed nearly 40% in four weeks. In addition, cytotoxicity assay showed that the prepared nanocomposite film i.e. CS7SEP3 exhibited better cell viability and cell proliferation rate against L929 mouse fibroblast cells as compared to CS and hence, the prepared nanocomposite film can be used as a promising candidate for wound management.

Hierarchical porous Mg2SiO4-CoFe2O4 nanomagnetic scaffold for bone cancer therapy and regeneration: Surface modification and in vitro studies.

3D multifunctional bone scaffolds have recently attracted more attention in bone tissue engineering because of addressing critical issues like bone cancer and inflammation beside bone regeneration. In this study, a 3D bone scaffold is fabricated from Mg2SiO4-CoFe2O4 nanocomposite which is synthesized via a two-step synthesis strategy and then the scaffold's surface is modified with poly-3-hydroxybutyrate (P3HB)-ordered mesoporous magnesium silicate (OMMS) composite to improve its physicochemical and biological properties. The Mg2SiO4-CoFe2O4 scaffold is fabricated through polymer sponge technique and the scaffold exhibits an interconnected porous structure in the range of 100-600 µm. The scaffold is then coated with OMMS/P3HB composite via dip coating and the physical, chemical, and biological-related properties of OMMS/P3HB composite-coated scaffold are assessed and compared to the non-coated and P3HB-coated scaffolds in vitro. It is found that, on the one hand, P3HB increases the cell attachment, proliferation, and compressive strength of the scaffold, but on the other hand, it weakens the bioactivity kinetic. Addition of OMMS to the coating composition is accompanied with significant increase in bioactivity kinetic. Besides, OMMS/P3HB composite-coated scaffold exhibits higher drug loading capacity and more controlled release manner up to 240 h than the other samples because of OMMS which has a high surface area and ordered mesoporous structure suitable for controlled release applications. The overall results indicate that OMMS/P3HB coating on Mg2SiO4-CoFe2O4 scaffold leads to a great improvement in bioactivity, drug delivery potential, compressive strength, cell viability, and proliferation. Moreover, OMMS/P3HB composite-coated scaffold has heat generation capability for hyperthermia-based bone cancer therapy and so it is suggested as a multifunctional scaffold with great potentials for bone cancer therapy and regeneration.

Effects of Sepiolite and Biochar on Enzyme Activity of Soil Contaminated by Cd and Atrazine.

The effects of sepiolite and biochar on the enzymatic activities of the soil in Cd- and atrazine-contaminated soils were studied. During the growth of pakchoi, the activities of acid phosphatase, sucrase, acid protease, and cellulase decreased, catalase activity increased, and urease activity decreased first and then increased. At the first harvest, compared with that for the control group, the soil pH after treatment with remediation materials increased from 5.41 to 7.43; the activities of urease, acid protease, and catalase increased by 62.8%, 38.6%, and 86.1%, respectively. And the activities of sucrase and acid phosphatase decreased by 17.3% and 24.7%, respectively. At the second harvest, the activities of acid phosphatase, acid protease, and cellulase continued to increase, but those of sucrase and catalase decreased. The results showed that soil enzyme activity was closely related to the type and addition of remediation materials, as well as the type of the enzyme.

Osteoblast/bone-tissue responses to porous surface of polyetheretherketone-nanoporous lithium-doped magnesium silicate blends' integration with polyetheretherketone.

The porous surface of a polyetheretherketone (PK)-nanoporous lithium-doped magnesium silicate (NLS) blend (PKNLS) was fabricated on a PK surface by layer-by-layer pressuring, sintering, and salt-leaching. As controls, porous surfaces of a PK/lithium-doped magnesium silicate blend (PKLS) and PK were fabricated using the same method. The results revealed that porosity, water absorption, and protein absorption of the porous surface of PKNLS containing macropores and nanopores were obviously enhanced compared to PKLS and PK containing macropores without nanopores. In addition, PKNLS, with both macroporostiy and nanoporosity, displayed the highest ability of apatite mineralization in simulated body liquid, indicating excellent bioactivity. In vitro responses (including adhesion, proliferation, and differentiation) of MC3T3E1 cells to PKNLS were significantly enhanced compared to PKLS and PK. In vivo implantation results showed that new bone grew into the macroporous surface of PKNLS, and the amount of new bone for PKNLS was the highest. In short, PKNLS integration with PK significantly promoted cells/bone-tissue responses and exhibited excellent osteogenesis in vivo, which might have great potential for bone repair.

Mechanical Strength, Surface Properties, Cytocompatibility and Antibacterial Activity of Nano Zinc-Magnesium Silicate/Polyetheretherketone Biocomposites.

In order to improve the biological activity and antibacterial properties of polyetheretherketone (PK) as bone implants, nano zinc-magnesium silicate (nZMS)/PK bioactive composites (nZPC) were fabricated. The results revealed that the mechanical properties, surface roughness and hydrophilicity of the nZPC gradually increased with nZMS content, in which nZPC with 50 w% of nZMS (50nZPC) exhibited the best properties. In addition, incorporation of nZMS into PK significantly improved the apatite mineralization ability of nZPC, which depended on nZMS content. Moreover, the attachment, proliferation and differentiation of MC3T3-E1 cells on nZPC were significantly enhanced with increasing nZMS content. Furthermore, after incorporation of nZMS into PK, the nZPC could inhibit the growth of Escherichia coli (E. coli), in which 50nZPC revealed the best antibacterial activity. The results suggested that 50nZMPC with good bioactivity, cytocompatibility and antibacterial activity might be a promising candidate as an implant for bone repair and anti-infection.

Electrophoretically deposited mesoporous magnesium silicate with ordered nanopores as an antibiotic-loaded coating on surface-modified titanium.

Infection is quite usual for implants after surgery and a systemic administration of antibiotics causes problems before the eradication of bacteria. Localized drug delivery from implants is an effective way by which the mentioned target can be met. In the current work, ordered mesoporous magnesium silicate (OMMS) is coated on plasma electrolytic oxidation (PEO)-modified titanium (Ti) substrate through electrophoretic deposition (EPD) and rifampin as an antibiotic is loaded on OMMS coating to be applied as an antibacterial coating. The immersion test into simulated body fluid and also potentiodynamic polarization assay are adopted to assess the in vitro bioactivity up to 7 days and corrosion resistance of the specimens, respectively. The double surface coatings of PEO and EPD are achieved on Ti substrate and the thickness for each one is found to be 4 and 25 µm, respectively. Regarding to drug delivery capability of OMMS as the EPD coating, the loading capacity is 25% and release trend sustains up to 96 h. The antibacterial activity and also cell viability of OMMS coating are significantly increased with rifampin loading. The results of our study exhibit that OMMS as a multifunctional coating deposited on the PEO-modified Ti substrate improves corrosion resistance, in vitro bioactivity, alkaline phosphatase activity, and mineralization of the substrate. Moreover, rifampin-loaded OMMS coating is not only able to prevent infection, but it also increases the osteogenesis cells viability. Therefore, rifampin-loaded OMMS coating on Ti is potentially regarded appropriate for orthopedic applications.

Enhanced biocompatibility and osteogenic potential of mesoporous magnesium silicate/polycaprolactone/wheat protein composite scaffolds.

BACKGROUND: Successful bone tissue engineering using scaffolds is primarily dependent on the properties of the scaffold, including biocompatibility, highly interconnected porosity, and mechanical integrity. METHODS: In this study, we propose new composite scaffolds consisting of mesoporous magnesium silicate (m_MS), polycaprolactone (PCL), and wheat protein (WP) manufactured by a rapid prototyping technique to provide a micro/macro porous structure. Experimental groups were set based on the component ratio: (1) WP0% (m_MS:PCL:WP =30:70:0 weight per weight; w/w); (2) WP15% (m_MS:PCL:WP =30:55:15 w/w); (3) WP30% (m_MS:PCL:WP =30:40:30 w/w). RESULTS: Evaluation of the properties of fabricated scaffolds indicated that increasing the amount of WP improved the surface hydrophilicity and biodegradability of m_MS/PCL/WP composites, while reducing the mechanical strength. Moreover, experiments were performed to confirm the biocompatibility and osteogenic differentiation of human mesenchymal stem cells (MSCs) according to the component ratio of the scaffold. The results confirmed that the content of WP affects proliferation and osteogenic differentiation of MSCs. Based on the last day of the experiment, ie, the 14th day, the proliferation based on the amount of DNA was the best in the WP30% group, but all of the markers measured by PCR were the most expressed in the WP15% group. CONCLUSION: These results suggest that the m_MS/PCL/WP composite is a promising candidate for use as a scaffold in cell-based bone regeneration.

[Effects of different concentrations of MgSiF(6) as electrolyte for micro-arc oxidation on the bond strength between titanium and porcelain].

Objective: To investigate the effects of different concentrations of MgSiF(6) as electrolyte on the bond strength between titanium and porcelain after micro-arc oxidation (MAO) treatment and screen the suitable concentration of MgSiF(6) that can improve the bond strength between titanium and porcelain. Methods: Four different concentrations of MgSiF(6) (10, 20, 30, 40 g/L) were chosen as MAO reaction solutions. Sandblasting treatment was selected as a control group. After porcelain was fused to each specimen, titanium-porcelain bond strengths were evaluated by the three-point bending test according to ISO 9693. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were adopted to evaluate the morphologies and elemental compositions of both the MAO coatings and the interfaces of the titanium-porcelain restoration. Results: The surface of titanium specimen in the control group was sharp and rough, while specimens in both 10 g/L group and 20 g/L group were porous and homogeneous. However, the pores found on the specimens in the latter group were larger in diameter (approximately 1.0-2.0 µm) than those on the former one (0.2-0.5 µm). The bond strengths of the control group and the experimental groups (10, 20, 30, 40 g/L MgSiF(6)) were (27.08±3.16), (38.18±2.65), (44.75±2.21), (36.44±2.04), (31.04±2.59) MPa, respectively. All the experimental groups showed higher bond strengths than the control group did (P<0.05), and the bond strength of 20 g/L MgSiF(6) group was significantly higher than those of the other groups (P<0.05). Besides, the interfaces between titanium and porcelain were tight and compact in the 20 g/L group, while different amounts of pores and cracks were visible in the other groups. Additionally, after the three-point bending test, few residual porcelains could be observed on the surfaces of specimens in the control group. Conclusions: MAO treatment with 20 g/L MgSiF(6) on titanium can improve bonding strength between titanium and porcelain.

Improved mycelia and polysaccharide production of Grifola frondosa by controlling morphology with microparticle Talc.

BACKGROUND: Mushroom showed pellet, clump and/or filamentous mycelial morphologies during submerged fermentation. Addition of microparticles including Talc (magnesium silicate), aluminum oxide and titanium oxide could control mycelial morphologies to improve mycelia growth and secondary metabolites production. Here, effect of microparticle Talc (45 µm) addition on the mycelial morphology, fermentation performance, monosaccharide compositions of polysaccharides and enzymes activities associated with polysaccharide synthesis in G. frondosa was well investigated to find a clue of the relationship between polysaccharide biosynthesis and morphological changes. RESULTS: Addition of Talc decreased the diameter of the pellets and increased the percentage of S-fraction mycelia. Talc gave the maximum mycelial biomass of 19.25 g/L and exo-polysaccharide of 3.12 g/L at 6.0 g/L of Talc, and mycelial polysaccharide of 0.24 g/g at 3.0 g/L of Talc. Talc altered the monosaccharide compositions/percentages in G. frondosa mycelial polysaccharide with highest mannose percentage of 62.76 % and lowest glucose percentage of 15.22 % followed with the corresponding changes of polysaccharide-synthesis associated enzymes including lowest UDP-glucose pyrophosphorylase (UGP) activity of 91.18 mU/mg and highest UDP-glucose dehydrogenase (UGDG) and GDP-mannose pyrophosphorylase (GMPPB) activities of 81.45 mU/mg and 93.15 mU/mg. CONCLUSION: Our findings revealed that the presence of Talc significantly changed the polysaccharide production and sugar compositions/percentages in mycelial and exo-polysaccharides by affecting mycelial morphology and polysaccharide-biosynthesis related enzymes activities of G. frondosa.

Influences of doping mesoporous magnesium silicate on water absorption, drug release, degradability, apatite-mineralization and primary cells responses to calcium sulfate based bone cements.

In this study, composite cements containing mesoporous magnesium silicate (m-MS) and calcium sulfate (CS) were fabricated. The results revealed that the setting time of the m-MS/CS composite cements (m-MSC) slightly prolonged with the increase of m-MS content while the compressive strength suffered a little loss. The doping of m-MS improved the water absorption, drug release (vancomycin) and degradability of the m-MSC in Tris-HCl solution (pH=7.4). In addition, addition of m-MS facilitated the apatite-mineralization of m-MSC in simulated body fluid (SBF), indicating good bioactivity. For cell cultural experiments, the results revealed that the m-MSC promoted the cells adhesion and proliferation, and improved the alkaline phosphatase (ALP) activity of MC3T3-E1 cells, revealing good cytocompatibility. It could be suggested that the m-MSC might be promising cements biomaterials for bone tissue regeneration.

Combined chemical and physical transformation method with RbCl and sepiolite for the transformation of various bacterial species.

DNA transformation that delivers plasmid DNAs into bacterial cells is fundamental in genetic manipulation to engineer and study bacteria. Developed transformation methods to date are optimized to specific bacterial species for high efficiency. Thus, there is always a demand for simple and species-independent transformation methods. We herein describe the development of a chemico-physical transformation method that combines a rubidium chloride (RbCl)-based chemical method and sepiolite-based physical method, and report its use for the simple and efficient delivery of DNA into various bacterial species. Using this method, the best transformation efficiency for Escherichia coli DH5α was 4.3×106CFU/µg of pUC19 plasmid, which is higher than or comparable to the reported transformation efficiencies to date. This method also allowed the introduction of plasmid DNAs into Bacillus subtilis (5.7×103CFU/µg of pSEVA3b67Rb), Bacillus megaterium (2.5×103CFU/µg of pSPAsp-hp), Lactococcus lactis subsp. lactis (1.0×102CFU/µg of pTRKH3-ermGFP), and Lactococcus lactis subsp. cremoris (2.2×102CFU/µg of pMSP3535VA). Remarkably, even when the conventional chemical and physical methods failed to generate transformed cells in Bacillus sp. and Enterococcus faecalis, E. malodoratus and E. mundtii, our combined method showed a significant transformation efficiency (2.4×104, 4.5×102, 2×101, and 0.5×101CFU/µg of plasmid DNA). Based on our results, we anticipate that our simple and efficient transformation method should prove usefulness for introducing DNA into various bacterial species without complicated optimization of parameters affecting DNA entry into the cell.

Biocompatibility and bioactivity of porous polymer-derived Ca-Mg silicate ceramics.

Magnesium is a trace element in the human body, known to have important effects on cell differentiation and the mineralisation of calcified tissues. This study aimed to synthesise highly porous Ca-Mg silicate foamed scaffolds from preceramic polymers, with analysis of their biological response. Akermanite (Ak) and wollastonite-diopside (WD) ceramic foams were obtained from the pyrolysis of a liquid silicone mixed with reactive fillers. The porous structure was obtained by controlled water release from selected fillers (magnesium hydroxide and borax) at 350°C. The homogeneous distribution of open pores, with interconnects of modal diameters of 160-180µm was obtained and maintained after firing at 1100°C. Foams, with porosity exceeding 80%, exhibited compressive strength values of 1-2MPa. In vitro studies were conducted by immersion in SBF for 21days, showing suitable dissolution rates, pH and ionic concentrations. Cytotoxicity analysis performed in accordance with ISO10993-5 and ISO10993-12 standards confirmed excellent biocompatibility of both Ak and WD foams. In addition, MC3T3-E1 cells cultured on the Mg-containing scaffolds demonstrated enhanced osteogenic differentiation and the expression of osteogenic markers including Collagen Type I, Osteopontin and Osteocalcin, in comparison to Mg-free counterparts. The results suggest that the addition of magnesium can further enhance the bioactivity and the potential for bone regeneration applications of Ca-silicate materials. STATEMENTS OF SIGNIFICANCE: Here, we show that the incorporation of Mg in Ca-silicates plays a significant role in the enhancement of the osteogenic differentiation and matrix formation of MC3T3-E1 cells, cultured on polymer-derived highly porous scaffolds. Reduced degradation rates and improved mechanical properties are also observed, compared to Mg-free counterparts, suggesting the great potential of Ca-Mg silicates as bone tissue engineering materials. Excellent biocompatibility of the new materials, in accordance to the ISO10993-5 and ISO10993-12 standard guidelines, confirms the preceramic polymer route as an efficient synthesis methodology for bone scaffolds. The use of hydrated fillers as porogens is an additional novelty feature presented in the manuscript.

Anti-inflammatory, anti-bacterial, and cytotoxic activity of fibrous clays.

Produced worldwide at 1.2m tons per year, fibrous clays are used in the production of pet litter, animal feed stuff to roof parcels, construction and rheological additives, and other applications needing to replace long-fiber length asbestos. To the authors' knowledge, however, information on the beneficial effects of fibrous clays on health remains scarce. This paper reports on the anti-inflammatory, anti-bacterial, and cytotoxic activity by sepiolite (Vallecas, Spain) and palygorskite (Torrejon El Rubio, Spain). The anti-inflammatory activity was determined using the 12-O-tetradecanoylphorbol-13-acetate (TPA) and myeloperoxidase (MPO) methods. Histological cuts were obtained for quantifying leukocytes found in the epidermis. Palygorkite and sepiolite caused edema inhibition and migration of neutrophils ca. 68.64 and 45.54%, and 80 and 65%, respectively. Fibrous clays yielded high rates of infiltration, explained by cleavage of polysomes and exposure of silanol groups. Also, fibrous clays showed high inhibition of myeloperoxidase contents shortly after exposure, but decreased sharply afterwards. In contrast, tubular clays caused an increasing inhibition of myeloperoxidase with time. Thus, clay structure restricted the kinetics and mechanism of myeloperoxidase inhibition. Fibrous clays were screened in vitro against human cancer cell lines. Cytotoxicity was determined using the protein-binding dye sulforhodamine B (SRB). Exposing cancer human cells to sepiolite or palygorskite showed growth inhibition varying with cell line. This study shows that fibrous clays served as an effective anti-inflammatory, limited by chemical transfer and cellular-level signals responding exclusively to an early exposure to clay, and cell viability decreasing significantly only after exposure to high concentrations of sepiolite.

In vitro degradability, bioactivity and cell responses to mesoporous magnesium silicate for the induction of bone regeneration.

Mesoporous magnesium silicate (m-MS) was synthesized, and the in vitro degradability, bioactivity and primary cell responses to m-MS were investigated. The results suggested that the m-MS with mesoporous channels of approximately 5nm possessed the high specific surface area of 451.0m(2)/g and a large specific pore volume of 0.41cm(3)/g compared with magnesium silicate (MS) without mesopores of 75m(2)/g and 0.21cm(3)/g, respectively. The m-MS was able to absorb a large number of water, with water absorption of 74% compared with 26% for MS. The m-MS was also degradable in a Tris-HCl solution, with a weight loss ratio of 40wt% after a 70-day immersion period. The m-MS exhibited good in vitro bioactivity, inducing apatite formation on its surfaces after soaking in simulated body fluid (SBF) at a faster rate than observed for MS. The m-MS surface clearly promoted the proliferation and differentiation of MC3T3-E1 cells, and their normal cell morphology indicated excellent cytocompatibility. This study suggested that mesoporous magnesium silicate with a high specific surface area and pore volume had suitable degradability and good bioactivity and biocompatibility, making it an excellent candidate biomaterial for the induction of bone regeneration.

The role of carnitine on ovariectomy and inflammation-induced osteoporosis in rats.

This study was carried out to assess the protective bone-sparing effect of carnitine with anti-inflammatory properties on chronic inflammation-induced bone loss in ovariectomised (OVX) rats. A total of 64 rats were divided into eight groups. Sixteen rats were sham-operated (SH) while the others were ovariectomised (OVX). (1) SH, (2) sham + inflammation (SHinf), (3) OVX, (4) ovariectomy + inflammation (OVXinf), (5) OVX + CAR1, (6) OVX + CAR2, (7) OVXinf + CAR1, (8) OVXinf + CAR2. After the ovariectomy surgery, all the groups (3, 4, 5, 6, 7, and 8) were allowed to recover for two months. Sixty days after the OVX, inflammation was induced by subcutaneous injections of talc in groups 2, 4, 7, and 8. Group 5 and 7 were given 50 mg/kg CAR; Group 6 and 8 were given 100 mg/kg CAR from the 60th to the 80th day. Serum levels of TNF-α, IL-1, IL-6, OP, and OC were assessed to determine inflammation and to evaluate osteoblastic activity. Bone mineral density (BMD) was assessed by dual energy X-ray absorptiometry in femur bones of rats. Carnitine administration was able to restore BMD up to values measured in both the OVX and the SH animals. The serum levels of TNF-α, IL-1ß, and IL-6 were increased significantly in the OVXinf rats compared with the SH group. In OVX rats, inflammation which is evaluated by serum cytokine levels exacerbated this bone loss, as supported by values of BMD of the total femur. The two different doses of carnitine reduced bone loss and improved inflammatory biomarkers.

The animal food supplement sepiolite promotes a direct horizontal transfer of antibiotic resistance plasmids between bacterial species.

Animal fodder is routinely complemented with antibiotics together with other food supplements to improve growth. For instance, sepiolite is currently used as a dietary coadjuvant in animal feed, as it increases animal growth parameters and improves meat and derived final product quality. This type of food additive has so far been considered innocuous for the development and spread of antibiotic resistance. In this study, we demonstrate that sepiolite promotes the direct horizontal transfer of antibiotic resistance plasmids between bacterial species. The conditions needed for plasmid transfer (sepiolite and friction forces) occur in the digestive tracts of farm animals, which routinely receive sepiolite as a food additive. Furthermore, this effect may be aggravated by the use of antibiotics supplied as growth promoters.

Assessment of natural sepiolite on cadmium stabilization, microbial communities, and enzyme activities in acidic soil.

A pot trial was conducted to assess the efficiency of sepiolite-induced cadmium (Cd) immobilization in ultisoils. Under Cd concentrations of 1.25, 2.5, and 5 mg kg(-1), the available Cd in the soil after the application of 1-10 % sepiolite decreased by a maximum of 44.4, 23.0, and 17.0 %, respectively, compared with no sepiolite treatments. The increase in the values of soil enzyme activities and microbial number proved that a certain metabolic recovery occurred after sepiolite treatment. The dry biomass of spinach (Spinacia oleracea) increased with increasing sepiolite concentration in the soil. However, the concentration (dry weight) of Cd in the spinach shoots decreased with the increase in sepiolite dose, with maximum reduction of 92.2, 90.0, and 84.9 %, respectively, compared with that of unamended soils. Under a Cd level of 1.25 mg kg(-1), the Cd concentration in the edible parts of spinach at 1 % sepiolite amendment was lower than 0.2 mg kg(-1) fresh weight, the maximum permissible concentration (MPC) of Cd in vegetable. Even at higher Cd concentrations (2.5 and 5 mg kg(-1)), safe spinach was produced when the sepiolite treatment was up to 5 %. The results showed that sepiolite-assisted remediation could potentially succeed on a field scale by decreasing Cd entry into the food chain.

Prediction of osteoconductive activity of modified potassium fluorrichterite glass-ceramics by immersion in simulated body fluid.

Potassium fluorrichterite (KNaCaMg(5)Si(8)O(22)F(2)) glass-ceramics were modified by either increasing the concentration of calcium (GC5) or by the addition of P(2)O(5) (GP2). The stoichiometric composition (GST), GC5 and GP2 were soaked in simulated body fluid (SBF) along with 45S5-type bioglass as a control. After immersion, surface analyses were performed using thin-film X-ray diffraction (TF-XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier-transform infrared (reflection) spectroscopy (FT-IR). All compositions showed the formation of a calcium phosphate rich surface layer in SBF; GST, GP2 and the bioglass control within 7 days of immersion and GC5 after 14 days. It was concluded that all compositions were likely to be osteoconductive in vivo, with GP2 providing the best performance in terms of the combination of rapid formation of the surface layer and superior mechanical properties. This glass-ceramic system has potential as a load bearing bioceramic for fabrication of medical devices intended for skeletal tissue repair.

Determination of bioavailable fluoride from sepiolite by "in vivo" digestibility assays.

This work presents a study of the bioavailability and distribution of fluoride in tissues of animals (Wistar rats) which were fed with a poultry feeding that contains sepiolite as an additive. The determination of fluoride concentration was carried out by potentiometric measurements using a fluoride selective electrode. The quantification was done using the standard addition method with enough accuracy and precision in all the assays. The results demonstrate that fluoride present in sepiolite is not bioavailable. The digestion process does not extract all the fluoride from sepiolite, so sepiolite can be use in poultry feedings without any risk. These studies have contributed to the discussions at EU level about extraction procedures and F(-) determination in feed material of mineral origin.