A New Species of Pararrhopalites Bonet & Tellez (Collembola, Symphypleona, Sminthuridae) from Iron Caves in Brazil.

A second species of the genus Pararrhopalites is described from caves inserted in iron ore lithology. Both species present a particular sensory organ in the interantennal region. The new species, Pararrhopalites ubiquum n.sp., has a wider distribution and it is not restricted to a single cave, as it is the case of Pararrhopalites sideroicus Zeppelini & Brito, in Fla Entomol 97(4):1733-1744, 2014, being found even in the Mesovoid Shallow Substratum. An update to the previously published identification key is presented.

Chemical and topographical influence of hydroxyapatite and beta-tricalcium phosphate surfaces on human osteoblastic cell behavior.

The objective of this work was to evaluate the relative role of the calcium phosphate surface chemistry and surface topography on human osteoblast behavior. Highly dense phosphate ceramics (single-phase hydroxyapatite HA and beta-tricalcium phosphates TCP) presenting two distinct nano roughnesses were produced. Some samples were gold-sputter coated in order to conveniently mask the surface chemical effects (without modification of the original roughness) and to study the isolated effect of surface topography on cellular behavior. Our results indicated that the nanotopography of the studied ceramics had no effect on the cellular adhesion (cell spreading, focal contacts and stress fibers formation). On the contrary, strong topographical effects were verified on cell proliferation and differentiation. Moreover, the phosphate chemistry was responsible for changes in adhesion, proliferation and cell differentiation. On TCP, it was shown that the main influent parameter was surface chemistry, which negatively affected the initial cell adhesion but positively affected the subsequent stage of proliferation and differentiation. On HA, the main influent parameter was surface topography, which increased cell differentiation but lowered proliferation.

Temperature-programmed desorption as a tool for quantification of protein adsorption capacity in micro- and nanoporous materials.

The protein adsorption capacity of porous sorbents is generally obtained by measuring the concentration of proteins desorbed from the materials after treatment by a detergent, or by measuring the decrease of protein concentration in the solution. These methods have some drawbacks and often lead to a low precision in the determination of the adsorption capacities. We describe in this paper a new method that allows to directly quantify the amount of proteins adsorbed on porous materials. This method is based on the quantitative analysis by mass spectrometry of some low mass gaseous species which evolve from the biomolecules during the heat treatment of a temperature-programmed desorption analysis (TPD-MS). The method has been applied to bovine serum albumin and cytochrome C adsorbed on an activated carbon. The adsorption uptake of the proteins on the carbon material could be measured by this direct analysis. A comparison with the depletion method was done, it shows that the two methods are complementary. The depletion method allows a determination of the total adsorption capacity, while the TPD-MS method focus on irreversible capacity.

Surface energy of hydroxyapatite and beta-tricalcium phosphate ceramics driving serum protein adsorption and osteoblast adhesion.

The main objective of this work was to evaluate the specific role of calcium phosphates surface energy on serum protein adsorption and human osteoblast adhesion, by isolating chemical effects from those caused by topography. Highly dense phosphate ceramics (single-phase hydroxyapatite HA and beta-tricalcium phosphates beta-TCP) presenting two distinct nano roughnesses were produced. Some samples were gold-sputter coated in order to conveniently mask the surface chemical effects (without modification of the original roughness) and to study the isolated effect of surface topography on cellular behavior. The results indicated that the nano topography of calcium phosphates strongly affected the protein adsorption process, being more important than surface chemistry. The seeding efficacy of osteoblasts was not affected nor by the topography neither by the calcium phosphate chemistries but the beta-TCP chemistry negatively influenced cell spreading. We observed that surface hydrophobicity is another way to change protein adsorption on surfaces. The decrease of the polar component of surface energy on gold-coated samples leaded to a decreased albumin and fibronectin adsorption but to an increased cell adhesion. Overall, this work contributes to better understand the role of topography and surface chemistry of calcium phosphates in serum protein adsorption and osteoblast adhesion.

Surface topography modulates the osteogenesis in human bone marrow cell cultures grown on titanium samples prepared by a combination of mechanical and acid treatments.

Titanium samples of different roughness R(a) and morphology were prepared using a combination of mechanical (grinding with a SiC paper or blasting with aluminum oxide particles with 65 or 250 microm) and chemical (attack with a sulphuric acid based solution or a hydrofluoric acid based solution) treatments. The biological performance of the prepared surfaces was evaluated using human bone marrow osteoblastic cell cultures. Mechanically treated samples presented different R(a) values and surface morphology. The hydrofluoric acid solution was more effective than the sulphuric acid solution in smoothing titanium surface and also in eliminating aluminum contamination resulting from the blasting process. Bone marrow cells seeded on the different titanium samples showed a similar pattern of behavior during cell attachment and spreading. Cells proliferated very well on all the titanium surfaces and cell growth was observed during approximately two to three weeks. The samples treated with the hydrofluoric acid solution presented higher alkaline phosphatase activity. Only the blasted samples treated with the acid solutions allowed seeded bone marrow cells to form a mineralized extracellular matrix. The best biological performance was found in the blasted samples treated with the hydrofluoric acid solution, which could be related to the characteristic microtopography of these samples that presented a homogeneous and smooth roughness.

Effect of process parameters on the characteristics of porous calcium phosphate ceramics for bone tissue scaffolds.

Porous hydroxyapatite (HA) has already been widely used as a bone substitute due to its similarity with the mineral part of the bone. In this work, cylindrical tablets with micro and macro porosity were produced from stoichiometric and deficient hydroxyapatites by using naphthalene as porosifier agent. The influence of the processing parameters such as Ca/P ratio of start material, calcination temperature, and naphthalene content on the characteristics of porous calcium phosphate tablets was evaluated. Three mineral phases-HA, alpha-TCP (alpha tri-calcium phosphate), and beta-TCP (beta tricalcium phos-phate)-with variable contents were identified by x-ray diffraction (XRD) and Fourier-transformed infrared spectroscopy (FT-IR). Image analysis and density measurements were used to characterize sample porosity. As expected, the total porosity of the calcinated material is not dependent on the stoichiometry of the precursor hydroxyapatite. For calcium-deficient hydroxyapatite, the increase in naphthalene content contributes to stabilize alpha-TCP phase, altering the relative phases content.