Bioactive glass/polymer composite scaffolds mimicking bone tissue

The aim of this work was the preparation and characterization of scaffolds with mechanical and functional properties able to regenerate bone. Porous scaffolds made of chitosan/gelatin (POL) blends containing different amounts of a bioactive glass (CEL2), as inorganic material stimulating biomineralization, were fabricated by freeze-drying. Foams with different compositions (CEL2/POL 0/100; 40/60; 70/30 wt %/wt) were prepared. Samples were crosslinked using genipin (GP) to improve mechanical strength and thermal stability. The scaffolds were characterized in terms of their stability in water, chemical structure, morphology, bioactivity, and mechanical behavior. Moreover, MG63 osteoblast-like cells and periostealderived stem cells were used to assess their biocompatibility. CEL2/POL samples showed interconnected pores having an average diameter ranging from 179 6 5 lm for CEL2/POL 0/100 to 136 6 5 lm for CEL2/POL 70/30. GP-crosslinking and the increase of CEL2 amount stabilized the composites to water solution (shown by swelling tests). In addition, the SBF soaking experiment showed a good bioactivity of the scaffold with 30 and 70 wt % CEL2. The compressive modulus increased by increasing CEL2 amount up to 2.1 6 0.1 MPa for CEL2/POL 70/30. Dynamical mechanical analysis has evidenced that composite scaffolds at low requencies showed an increase of storage and loss modulus with increasing frequency; furthermore, a drop of E0 and E00 at 1 Hz was observed, and for higher frequencies both moduli increased again. Cells displayed a good ability to interact with the different tested scaffolds which did not modify cell metabolic activity at the analyzed points. MTT test proved only a slight difference between the two cytotypes analyze

Synthesis and in-vitro cytotoxicity analysis of microwave irradiated nano-apatites

NOTICE: this is the author’s version of a work that was accepted for publication in Ceramics International. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in CERAMICS INTERNATIONAL, [VOL 39, ISSUE 4, (2013)] DOI 10.1016/j.ceramint.2012.11.017Nano-sized calcium deficient apatite (CDA) micelles were synthesized through microwave assisted the wet precipitation technique. Cetyltrimethylammonium bromide (CTAB) was employed as surface template to furnish the CDA particles with tailored size and shape. As-precipitated CDA was heat treated to observe the effect of heat treatment temperature on the interatomic rearrangement of entities within the apatite lattice. This transformation is responsible for conversion of CDA to β-tricalcium phosphate (β-TCP) at specific temperature. The phase purity, particles size, morphology and transformation kinetics were analyzed using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA). In-vitro studies were performed on β-TCP with three cell lines: osteoblasts, HeLa, and SF 767. The results showed that nano-sized particles were successfully synthesized in short time. The cells had appreciable proliferation/attachment on the surface of these nano-particles. It is concluded that the microwave irradiated synthesized β-TCP has good capacity in terms of biocompatibility and has the potential to be used in hard tissue regeneration applications.Nano-sized calcium deficient apatite (CDA) micelles were synthesized through microwave assisted the wet precipitation technique. Cetyltrimethylammonium bromide (CTAB) was employed as surface template to furnish the CDA particles with tailored size and shape. As-precipitated CDA was heat treated to observe the effect of heat treatment temperature on the interatomic rearrangement of entities within the apatite lattice. This transformation is responsible for conversion of CDA to β-tricalcium phosphate (β-TCP) at specific temperature. The phase purity, particles size, morphology and transformation kinetics were analyzed using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA). In-vitro studies were performed on β-TCP with three cell lines: osteoblasts, HeLa, and SF 767. The results showed that nano-sized particles were successfully synthesized in short time. The cells had appreciable proliferation/attachment on the surface of these nano-particles. It is concluded that the microwave irradiated synthesized β-TCP has good capacity in terms of biocompatibility and has the potential to be used in hard tissue regeneration applications

Natural-based nanocomposites for bone tissue engineering and regenerative medicine: a review

Tissue engineering and regenerative medicine has been providing exciting technologies for the development of functional substitutes aimed to repair and regenerate damaged tissues and organs. Inspired by the hierarchical nature of bone, nanostructured biomaterials are gaining a singular attention for tissue engineering, owing their ability to promote cell adhesion and proliferation, and hence new bone growth, compared with conventional microsized materials. Of particular interest are nanocomposites involving biopolymeric matrices and bioactive nanosized fi llers. Biodegradability, high mechanical strength, and osteointegration and formation of ligamentous tissue are properties required for such materials. Biopolymers are advantageous due to their similarities with extracellular matrices, specifi c degradation rates, and good biological performance. By its turn, calcium phosphates possess favorable osteoconductivity, resorbability, and biocompatibility. Herein, an overview on the available natural polymer/calcium phosphate nanocomposite materials, their design, and properties is presented. Scaffolds, hydrogels, and fi bers as biomimetic strategies for tissue engineering, and processing methodologies are described. The specifi c biological properties of the nanocomposites, as well as their interaction with cells, including the use of bioactive molecules, are highlighted. Nanocomposites in vivo studies using animal models are also reviewed and discussed.  The research leading to this work has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement no REGPOT-CT2012-316331-POLARIS, and from QREN (ON.2 - NORTE-01-0124-FEDER-000016) cofinanced by North Portugal Regional Operational Program (ON.2 - O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF)

Search for massive resonances in dijet systems containing jets tagged as W or Z boson decays in pp collisions at √s=8 TeV

Peer reviewe

Constraints on the Higgs boson width from off-shell production and decay to Z-boson pairs

Constraints are presented on the total width of the recently discovered Higgs boson, GH, using its relative on-shell and off-shell production and decay rates to a pair of Z bosons, where one Z boson decays to an electron or muon pair, and the other to an electron, muon, or neutrino pair. The analysis is based on the data collected by the CMS experiment at the LHC in 2011 and 2012, corresponding to integrated luminosities of 5.1fb-1 at a center-of-mass energy vs=7 TeV and 19.7fb-1at vs=8 TeV. A simultaneous maximum likelihood fit to the measured kinematic distributions near the resonance peak and above the Z-boson pair production threshold leads to an upper limit on the Higgs boson width of GH<22 MeV at a 95% confidence level, which is 5.4 times the expected value in the standard model at the measured mass of mH=125.6 GeV