Development and characterisation of bilayered periosteum-inspired composite membranes based on sodium alginate-hydroxyapatite nanoparticles.

Background And Aim: Membranes for guided bone regeneration should have a mechanical structure and a chemical composition suitable for mimicking biological structures. In this work, we pursue the development of periosteum-inspired bilayered membranes obtained by crosslinking alginate with different amounts of nanohydroxyapatite.

Experiments: Alginate-nanohydroxyapatite interaction was studied by rheology and infrared spectroscopy measurements.

Synthetic anionic surfaces can replace microparticles in stimulating burst coagulation of blood plasma.

Biomaterials are frequently evaluated for pro-coagulant activity but usually in the presence of microparticles (MPs), cell-derived vesicles in blood plasma whose phospholipid surfaces allow coagulation factors to set up as functional assemblies. We tested the hypothesis that synthetic anionic surfaces can catalyze burst thrombin activation in human blood plasma in the absence of MPs. In a thromboelastography (TEG) assay with plastic sample cups and pins, recalcified human citrated platelet-poor plasma spontaneously burst-coagulated but with an unpredictable clotting time whereas plasma depleted of MPs by ultracentrifugation failed to coagulate.

Manipulation of Mg-Ca Switch on the Development of Bone Mimetic Hydroxyapatite.

Ionic substitution can affect essential physicochemical properties leading to a specific biological behavior upon implantation. Therefore, it has been proposed as a tool to increase the biological efficiency of calcium phosphate based materials. In the following study, we have evaluated the contribution of an important cation in nature, Mg, into the structure of previously studied biocompatible and biodegradable hydroxyapatite (HA) nanorods and its subsequent effect on its chemical, morphology, and bone mimetic articulation.

Albumin-mediated deposition of bone-like apatite onto nano-sized surfaces: Effect of surface reactivity and interfacial hydration.

The bioactivity of an implant is displayed on its ability to induce heterogeneous nucleation of biogenic apatite onto its surface upon immersion in body fluids; forming, through this layer, a stable bond with the host tissue. The present article evaluates the bioactivity of different nanostructured substrates based on synthetic hydroxyapatite (HA) and titania (TiO) nanoparticles, where we extend the debate regarding the selective roles played by the presence of albumin on the biogenic apatite coating evolution. The substrates bone-bonding potential was evaluated by keeping the materials in contact with Simulated Body Fluid, while the influence of the presence of Bovine Serum Albumin in bioactivity was analyzed by a spectrophotometric technique.

Bone-repair properties of biodegradable hydroxyapatite nano-rod superstructures.

Nano-hydroxyapatite (nano-HAp) materials show an analogous chemical composition to the biogenic mineral components of calcified tissues and depending on their topography they may mimic the specific arrangement of the crystals in bone. In this work, we have evaluated the potential of four synthesized nano-HAp superstructures for the in vitro conditions of bone-repair. Experiments are underway to investigate the effects of the material microstructure, surface roughness and hydrophilicity on their osseo-integration, osteo-conduction and osteo-induction abilities.

Photoluminescent SBA-16 Rhombic Dodecahedral Particles: Assembly, Characterization, and ab Initio Modeling.

Nowadays, the use of polyhedral instead of spherical particles as building blocks of engineering new materials has become an area of particular effort in the scientific community. Therefore, fabricating in a reproducible manner large amounts of uniform crystal-like particles is a huge challenge. In this work we report a low reagent-consuming binary surfactant templated method mediated by a hydrothermal treatment as a facile and controllable route for the synthesis of crystal-like rombdodecahedral particles exhibiting SBA-16 mesoporosity.

Analyzing the hydrodynamic and crowding evolution of aqueous hydroxyapatite-gelatin networks: Digging deeper into bone scaffold design variables.

The hydration of the polypeptide network is a determinant factor to be controlled on behalf of the design of precise functional tissue scaffolding. Here we present an exhaustive study of the hydrodynamic and crowding evolution of aqueous gelatin-hydroxyapatite systems with the aim of increasing the knowledge about the biomimesis of collagen mineralization; and how it can be manipulated for the preparation of collagenous derived frameworks with specific morphological characteristics. The solution's density and viscosity evaluation measurements in combination with spectroscopic techniques revealed that there is a progressive association of protein chain that can be influenced by the amount of hydroxyapatite nanorods.

Striped, bioactive Ce-TiO materials with peroxynitrite-scavenging activity.

Controlling aligned fiber micro-architectures to simulate the extracellular matrix for inducing important biological functions is a key challenge with regard to successful tissue regeneration. Here we present a bottom-up microemulsion-mediated strategy to obtain highly bioactive and biocompatible, striped Ce-TiO nano-crystalline superstructures with ONOO scavenging activity. The employment of a bulkier organic ceria precursor in the material synthesis has several concurrent effects: (I) influencing the interfacial microemulsion droplet elasticity to create an aligned distribution of prismatic anatase nanoparticles causing the final lined morphology, (II) stabilizing the anatase active phase in a fine dispersed state and improving its resistance to the thermal anatase-rutile conversion, (III) indirectly favoring the rapid formation on the material surface of a hydroxyapatite layer composed of sphere-like globules of 3-5 μm in diameter essential for bone-bonding, and finally (IV) accelerating the ONOO degradation into less harmful species NO and O.

Manipulating the bioactivity of hydroxyapatite nano-rods structured networks: effects on mineral coating morphology and growth kinetic.

Background: Nano-hydroxyapatite particles have better bioactivity than the coarse crystals. So, they can be utilized for engineered tissue implants with improved efficiency over other materials. The development of materials with specific bioactive characteristics is still under investigation.

Highly efficient photoluminescence of SiO2 and Ce-SiO2 microfibres and microspheres.

Semiconductor nanocrystals and nanostructures have been extensively studied in the last few years due to their interesting optical and optoelectronic properties. Nevertheless, combining precise photoluminescence properties with controlled morphologies of SiO2 is a major hurdle for a broad range of basic research and technological applications. Here, we demonstrate that microemulsion droplet interfacial elasticity can be manipulated to induce definite morphologies associated with specific intrinsic and extrinsic photoluminescent defects in the silica matrix.

NFκB pathway is down-regulated by 1α,25(OH)(2)-vitamin D(3) in endothelial cells transformed by Kaposi sarcoma-associated herpes virus G protein coupled receptor.

We have previously demonstrated that 1α,25 dihydroxy-vitamin D(3) (1α,25(OH)(2)D(3)) has antiproliferative effects on the growth of endothelial cells transformed by the viral G protein-coupled receptor associated to Kaposi sarcoma (vGPCR). In this work, we have investigated whether 1α,25(OH)(2)D(3) exerts its growth inhibitory effects by inhibiting the Nuclear Factor κ B (NFκB) pathway which is highly activated by vGPCR. Cell proliferation studies demonstrated that 1α,25(OH)(2)D(3), similarly to bortezomib, a proteosome inhibitor that suppresses the activation of NFκB, reduced the proliferation of endothelial cells transformed by vGPCR (SVEC-vGPCR).