Effect of cerium-containing hydroxyapatite in bone repair in female rats with osteoporosis induced by ovariectomy

Osteoporosis is a public health problem, with bone loss being the main consequence. Hydroxyapatite (HA) has been largely used as a bioceramic to stimulate bone growth. In our work, a cerium-containing HA (Ce-HA) has been proposed and its effects on the antimicrobial and bone-inducing properties were investigated. The synthesis of the materials occurred by the suspension–precipitation method (SPM). The XRD (X-ray Diffraction) confirmed the crystalline phase, and the Rietveld refinement confirmed the crystallization of HA and Ce-HA in a hexagonal crystal structure in agreement with ICSD n◦ 26205. Characterizations by FT-IR (Fourier Transform Infrared Spectroscopy), XPS (X-ray Photoemission Spectroscopy), and FESEM-EDS (Field Emission Scanning Electron Microscope-Energy Dispersive X-ray Spectroscopy) confirmed the presence of cerium (Ce3+ and Ce4+ ). The antibacterial activity of Has was evaluated against Staphylococcus aureus 25,923 and Escherichia coli 25,922 strains, which revealed that the material has antimicrobial properties and the cytotoxicity assay indicated that Ce-containing HA was classified as non-toxic. The effects of Ce-HA on bone repair, after application in bone defects in the tibia of female rats with osteoporosis induced by ovariectomy (OVX), were evaluated. After 15 and 30 days of implantation, the samples were analyzed by Raman, histology and X-ray microtomography. The results showed that the animals that had the induced bone defects filled with the Ce-HA materials had more expressive bone neoformation than the control group.info:eu-repo/semantics/publishedVersio

Confinement and Time Immemorial: Prebiotic Synthesis of Nucleotides on a Porous Mineral Nanoreactor

International audienc

Sorção de chumbo numa sílica modificada obtida da crisotila: aplicação de isotermas

A silica was modified with three alcoxysilanes with different quantities of nitrogen, whose the silica obtained from chrysotile acid leaching. The modified silicas were applied in lead removal from aqueous solution, obtained the following capacities: 1.41, 0.78 e 0.60 mmol g-1 for the materials containing 3, 1 and 2 nitrogen in organic chains, respectively. The isotherms were adjusted using different models, and each material showed affinity to a model. The interactions were favorable and spontaneous from Freundlich model and Gibbs free energy, respectively.Uma sílica foi modificada com três alcoxissilanos com diferentes quantidades de nitrogênio, onde a sílica foi obtida da lixiviação ácida da crisotila (amianto). As sílicas modificadas foram aplicadas na remoção de chumbo de soluções aquosas, obtendo-se as seguintes capacidades: 1,41, 0,78 e 0,60 mmol g-1 para os materiais contendo 3, 1 e 2 átomos de nitrogênios nas cadeias orgânicas, respectivamente. As isotermas foram ajustadas usando diferentes modelos, onde cada material mostrou afinidade a um modelo. As interações foram favoráveis e espontâneas a partir do modelo de Freundlich e da energia livre de Gibbs, respectivamenteSorption of lead on modified silica obtained from chrysotile: isotherms applicationAbstractA silica was modified with three alcoxysilanes with different quantities of nitrogen, whose the silica obtained from chrysotile acid leaching. The modified silicas were applied in lead removal from aqueous solution, obtained the following capacities: 1.41, 0.78 e 0.60 mmol g-1 for the materials containing 3, 1 and 2 nitrogen in organic chains, respectively. The isotherms were adjusted using different models, and each material showed affinity to a model. The interactions were favorable and spontaneous from Freundlich model and Gibbs free energy, respectively

Adsorption and photostability of tetracycline onto different clays

EUROCLAY 2019, held in París (France), 1-5 July, 201

Understanding the effect of UV light in systems containing clay minerals and tetracycline

Clay minerals are natural materials that can, due to their physicochemical properties and different structures, accommodate organic species and improve their photoprotection capacities. Tetracycline (TC) is a well-known antibiotic, but there is little research on its photostability. The objective of this work was to investigate the photostability of tetracycline incorporated into the following pharmaceutical grade clay minerals: montmorillonite (Mt), palygorskite (Pal), sepiolite (Sep) and montmorillonite (Veegum©). Photostability tests were performed by exposing samples to UV light for 200 h. The adsorption behavior of the antibiotic molecule on different clay minerals was observed. The drug/clay mineral systems were characterized by X-ray diffraction (XRD), carbon elemental analyses, N2 adsorption/desorption isotherms, and thermogravimetry. The XRD results showed intercalation of tetracycline into the interlayer spacing of montmorillonite. In fibrous clay minerals, TC was located on the exterior surface as well as in the grooves and entrances of the structure's channels. Data from carbon elemental and specific surface area analyses indicated the incorporation of tetracycline into the clay mineral structures. Thermogravimetry showed differences in the profiles of thermal degradation in all irradiated and nonirradiated systems. For systems based on montmorillonite, the thermal results suggested hardening of the drug after UV radiation. For all analyzed samples, tetracycline incorporated into Veegum presented the highest stability under UV light. © 2019The authors would like to thank the Federal University of Piauí (UFPI), Universidad de Granada (UG), National Council for Scientific and Technological Development (CNPq) and the Interdisciplinary Laboratory for Advanced Materials - LIMAV for providing laboratory resources and the Fundacíon Carolina for fellowship

Gallium-Containing Hydroxyapatite as a Promising Material for Photocatalytic Performance

The development of photocatalystsor their modification to obtain new photocatalytic performances for the removal of contaminants is a challenge. Hydroxyapatite (HAp), (Ca10(PO4)6(OH)2), is an inorganic component with a high superficial area and low toxicity and the presence of metal in its structure can be an interesting strategy for the photocatalytic approach. This work aimed to synthesize gallium-containing HAp (Ga-HAp) as a promising material for photocatalytic performance. The synthesis was performed by the suspension–precipitation method. The material was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Morphological analysis employed field emission scanning electron microscope (FESEM) and the elemental analysis by energy-dispersive spectroscopy (EDS). To evaluate the photocatalytic activity, methylene blue (MB) dye was used as a pollutant model under UV light for 120 min. The influence of Ga-HAp concentration (0.25, 0.50, and 1.00 g·L−1) and kinetic reaction was also studied. The Ga-HAp was successfully obtained by the suspension–precipitation method. The structural characterization by XRD and FESEM-EDS elucidated the presence of gallium in the structure of hydroxyapatite. The XPS results indicated the substitution of gallium in the crystal lattice of the material. The discoloration rate of MB dye using Ga-Hap was calculated by pseudo first-order kinetics, and the best rate constant was 7.5 × 10−3 min−1 using 1.00 g·L−1 of photocatalyst. The concentration of Ga-HAp influenced the photocatalytic process, because the discoloration rate increased as a function of the concentration of material. Therefore, Ga-HAp is a promising material for environmental remediation