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This study describes a novel bioactive xerogel glass as a carrier for bone morphogenetic protein (BMP) and the value of this carrier in terms of stimulating osteogenic activity of rat stromal marrow cells in vitro. These cells were seeded onto the surface of xerogel glass disks with BMP either incorporated in the glass, adsorbed to the surface of the glass, or added to the culture media and then compared to cells on glass with no added BMP or to cells on tissue culture plastic (TCP) with and without BMP. Cells were cultured for 6 and 10 days and examined for total DNA, alkaline phosphatase activity, and osteocalcin and total protein production. Stromal cell differentiation, as measured by alkaline phosphatase activity and osteocalcin synthesis was most increased when the BMP was incorporated or adsorbed onto the xerogel glass. Cells on xerogel glass without BMP were more differentiated than cells grown on plastic with BMP, thereby demonstrating the additive effect of a bioactive substrate and BMP on osteoblastic cell differentiation. These data indicate that xerogel glass effects differentiation of cells with osteogenic potential and that it can serve as a delivery vehicle for BMP.

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Este trabalho apresenta uma rota alternativa para a preparação de nanodiscos de iodeto de chumbo (ca. 50-340 × 7Å, diâmetro × espessura) utilizando o macrocíclico cucurbit [7]urila como molde de síntese e agente estabilizante. Estas nanopartículas apresentam um deslocamento para o azul de gap óptico consistente com seu tamanho reduzido e confinamento quântico 1D. Suas espessuras são compatíveis com a de uma camada de iodeto de chumbo esfoliado, indicando que cucurbit [7]urila impede a formação de estruturas lamelares e limita o crescimento das nanopartículas. A estrutura, a morfologia e as propriedades destes discos foram verificadas por difratometria de raios X em pó (XRD), espectroscopia no UV-Visível, microscopia de força atômica (AFM), microscopia eletrônica de varredura com análise de fluorescência de raios X por dispersão de energia (SEM-EDS) e microscopia eletrônica de transmissão de alta resolução (HRTEM).This work presents an alternative route for the preparation of heavy metal iodide nanoparticles, particularly lead iodide nanodisks (ca. 50-340 × 7 Å, diameter × thickness), using the macrocycle cucurbit [7]uril as a synthetic template and stabilizing agent. These nanoparticles exhibit an opticalgap blue shift consistent with their small size and 1D quantum confinement. Their thicknesses are compatible with an exfoliated single layer of lead iodide, indicating that cucurbit [7]uril, preventing the stacking and formation of tactoids, thus limiting nanoparticles growth in the z direction. The structure, morphology and properties of these disks were analyzed by X-ray powder diffractometry (XRD), UV-Visible spectroscopy, atomic force microscopy (AFM), scanning electron microscopy with analysis of energy dispersive X-ray fluorescence (SEM-EDS) and high resolution transmission electron microscopy (HRTEM).Keywords: lead iodide, cucurbit [7]uril, synthetic template, nanodisks, quantum confinement IntroductionLead iodide is a lamellar solid consisting of layers of metal and iodide ions united by covalent bonds. Weak van der Waals interactions hold these layers together in a three dimensional sandwich-like semiconductor. This structure can be described as a hexagonal close-packed array of iodide anions with alternate layers of octahedral interstices occupied by lead(II) cations. Therefore, each layer can be described as a I-Pb-I sequence layer.1 Very interesting materials can be obtained by diminishing the PbI 2 particle size to the nanoscale in order to favor the appearance of new properties resultant of quantum confinement, such as those observed in zero-dimensional solids, quantum dots and other N-dimensional, quantumconfined nanomaterials. Quantum dots encounter many applications in several technological fields such as sensor devices and anti-counterfeiting systems, illumination (as high efficiency white-light emitting diodes), medicine (as cellular markers), lasers, solar cells and others.2-5 Another important property of lead iodide is its ability to form intercalation compounds with many chemical species, ...

This study describes a novel bioactive xerogel glass as a carrier for bone morphogenetic protein (BMP) and the value of this carrier in terms of stimulating osteogenic activity of rat stromal marrow cells in vitro. These cells were seeded onto the surface of xerogel glass disks with BMP either incorporated in the glass, adsorbed to the surface of the glass, or added to the culture media and then compared to cells on glass with no added BMP or to cells on tissue culture plastic (TCP) with and without BMP. Cells were cultured for 6 and 10 days and examined for total DNA, alkaline phosphatase activity, and osteocalcin and total protein production. Stromal cell differentiation, as measured by alkaline phosphatase activity and osteocalcin synthesis was most increased when the BMP was incorporated or adsorbed onto the xerogel glass. Cells on xerogel glass without BMP were more differentiated than cells grown on plastic with BMP, thereby demonstrating the additive effect of a bioactive substrate and BMP on osteoblastic cell differentiation. These data indicate that xerogel glass effects differentiation of cells with osteogenic potential and that it can serve as a delivery vehicle for BMP.

One new and nine explanted zirconia femoral heads were studied using glancing angle X-ray diffraction, scanning electron microscopy, and nanoindentation hardness techniques. All starting zirconia implants consisted only of tetragonal zirconia polycrystals (TZP). For comparison, one explanted alumina femoral head was also studied. Evidence for a surface tetragonal-to-monoclinic zirconia phase transformation was observed in some implants, the extent of which was varied for different in-service conditions. A strong correlation was found between increasing transformation to the monoclinic phase and decreasing surface hardness. Microscopic investigations of some of the explanted femoral heads revealed ultra high molecular weight polyethylene and metallic transfer wear debris.