Nowadays, most products for dental restoration are produced from acrylic resins based on heat-cured Poly(Methyl MethAcrylate) (PMMA). The addition of metal nanoparticles to organic materials is known to increase the surface hydrophobicity and to reduce adherence to biomolecules. This paper describes the use of nanostructured materials, TiO2and Fe2O3, for simultaneously coloring and/or improving the antimicrobial properties of PMMA resins. Nanoparticles of metal oxides were included during suspension polymerization to produce hybrid metal oxides-alginate-containing PMMA. Metal oxide nanoparticles were characterized by dynamic light scattering, and X-ray diffraction. Physicochemical characterization of synthesized resins was assessed by a combination of spectroscopy, scanning electron microscopy, viscometry, porosity, and mechanical tests. Adherence ofCandida albicanscells and cellular compatibility assays were performed to explore biocompatibility and microbial adhesion of standard and novel materials. Our results show that introduction of biocompatible metal nanoparticles is a suitable means for the improvement of conventional acrylic dental resins.
Nanocomposite materials consisting of monodisperse SiO 2 particles embedded in a polymerized resin matrix were produced by the adhesion of silica globules on the surface of a chemically modified phenolic-formaldehyde resin (MPFR) substrate that incorporates carboxylic groups in its molecules. Two routes were followed to obtain SiO 2 nanoparticles-MPFR materials. The first procedure consisted of the growth of an SiO 2 phase concurrently with the presence of MPFR molecules. The second procedure involved the preparation of a monodisperse SiO 2 sol that was subsequently mixed with an MPFR solution. The thermal curing of the MPFR resin phase at 80 • C brought about thin SiO 2 -MPFR flakes from samples obtained from procedure 1 whilst monolithic pieces arose from samples from procedure 2. During the curing process, silanol surface groups of the silica globules reacted with carboxylic groups of the MPFR molecules to create a reinforced SiO 2 -MPFR substance that displayed ester bonds across the interface. Thermal treatments of specimens prepared by procedure 2 were performed at 150, 250, 400, 600 and 800 • C to monitor the integrity of the resultant hybrid substrates. To assess the characteristics of SiO 2 -MPFR materials, some of the main chemical, structural and textural characteristics of several specimens have been determined via FTIR, SEM and N 2 adsorption studies.
The objective of this project was to synthesis and to comparative characterization of nanocrystalline opals. Synthesis technique called Stöber allows obtaining nano and micro particles monodisperse. Natural opal of origin Mexican was utilized as reference. The results obtained indicated crystalline phases in the opal, and the presence of water is shown through x-ray diffraction and the FTIR and Raman spectra, respectively. Scanning electron microscopy illustrated spherical nanoparticle of silicon. We conclude that the synthetic opal presents a mimetic character.
Chemotropic proteins guide neuronal projections to their final target during embryo development and are useful to guide axons of neurons used in transplantation therapies. Site-specific delivery of the proteins however is needed for their application in the brain to avoid degradation and pleiotropic affects. In the present study we report the use of Poly (ethylene glycol)-Silica (PEG-Si) nanocomposite gel with thixotropic properties that make it injectable and suitable for delivery of the chemotropic protein semaphorin 3A. PEG-Si gel forms a functional gradient of semaphorin that enhances axon outgrowth of dopaminergic neurons from rat embryos or differentiated from stem cells in culture. It is not cytotoxic and its properties allowed its injection into the striatum without inflammatory response in the short term. Long term implantation however led to an increase in macrophages and glial cells. The inflammatory response could have resulted from non-degraded silica particles, as observed in biodegradation assays.
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