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The magnetic properties of low filling factor Fe-nanoparticle monolayers separated by relatively thick Al2O3 layers were investigated in parallel and perpendicular external magnetic field. The thin film nanocomposites were prepared by sequential pulsed laser deposition on (100) Si substrates, and the monolayers contain single-domain, dispersive nanoparticles. When the magnetic field is oriented parallel to the layers, the composite exhibits superparamagnetism. However, in perpendicular field, the superferromagnetic order sets in, as revealed by the increase of the magnetic moment, the hysteresis persisting at high temperatures, and a smaller relaxation rate. The complex out of plane behavior of our nanocomposites in perpendicular field is attributed to quasi two-dimensionality and to the dispersion of the in-plane nanoparticle separation. [ABSTRACT FROM AUTHOR]

In this contribution we present the preparation and characterization of biocellulose nanowhiskers-MTA (mineral trioxide aggregates) cement composites for endodontic applications. Nanocrystalline biocellulose fibers were obtain by special procedure starting from bacterial cellulose grown and selected in special conditions. The prepared biocellulose nanowhiskers and commercial MTA cement were used for preparation of some composite: MTA-E (mineral trioxide aggregates-experimental), MTA-10% biocell and MTA-33% biocell cements. Considering one day hardened composites and taking into account XRD patterns and the thermal analysis data, we have concluded that the presence of biocellulose accelerates the hardening processes of MTA cement, decreasing in the same time the quantity of calcium hydroxide crystals. SEM images reveal, for the first time in the literature, crystalline hydrosilicates of high density grown around biocellulose nanowhiskers.The composite biocompatibility was good and was demonstrated by a test with HEp cells in ratio1 mg/ml MTA+33%biocel for 24h. Cells morphology and viability were identically with the ones of the untreated control. Investigations on composites morphology, weight losses, mineralogical composition and structure were performed by SEM, DTA, XRD and TEM respectively. [ABSTRACT FROM AUTHOR]

In this work, we report on the preparation and characterization of collagen-glass ceramic composites. The materials used for obtaining collagen-glass ceramic composites were collagen type I (Coll) as bioresorbable polymer and glass ceramic (GC) from CaO-SiO2-P2O5 system as bioactive material. After incorporation of GC into Coll in different ratios (Coll/GC ratio was 25/75 wt% and 75/25 wt%) and freeze-drying of them, the obtained composite materials (Coll/GC) can be used, according to our results, as potential composite scaffold for bone tissue engineering. Coll/GC composite biocompatibility, assessed by an in-vitro test (SBF soaking for a period of 14 days, at a temperature of 37°C) and cytotoxicity of these on endothelial cells, was very good. The collagen-glass ceramic composites were characterized from the point of view of their mineralogical composition (by XRD) and morphology (by SEM). At the surface of the specimens soaked in simulated body fluid (SBF) for a period of 14 days, at a temperature of 37°C was observed the formation of mainly hydroxiapatite with a spherical morphology. Furthermore, the biocompatibility assays show that these collagen-glass ceramic composites are suitable for tissue engineering. Fluorescent microscopy of endothelial cells after 5 days in culture with this scaffolds revealed a great viability, also confirmed by the measurements of metabolic activity of endothelial cells. [ABSTRACT FROM AUTHOR]

Silver nanoparticles were deposed on bacterial cellulose (BC) membranes using tannic acid as reducing agent. The synthesis of silver nanoparticles was confirmed by scanning electron microscopy (SEM), energy dispersive spectroscopy with X-ray (EDX) and UVVIS spectroscopy. The antimicrobial activity of BC-silver films was tested against E. coli K12-MG1655, all the composites having a good antimicrobial activity. These composites could be used for antimicrobial wound dressings. [ABSTRACT FROM AUTHOR]