Synthetic Crysotile Nano-Crystals as a Reference Standard to Investigate Surface-Induce Serum Albumin Structural Modifications

Geoinspired synthetic chrysotile, which represents an ideal asbestos reference standard, has been utilized to investigate homomolecular exchange of bovine serum albumin (BSA), the major plasma protein, between the adsorbed and dissolved state at the interface between asbestos fibers and biological medium. FTIR spectroscopy has been used to quantify BSA structural modifications due to surface adhesion on chrysotile fibers as a function of the surface coating extent. Circular dichroism spectroscopy has been used to investigate the adsorption/desorption equilibrium through analysis of the BSA structural perturbations after protein desorption from chrysotile surface. Data results show clearly that in the solid state BSA modifications are driven by surface interaction with the substrate, following a bimodal adsorption evidenced by two different binding constants. On the other hand, BSA desorbed in solution is able to rearrange, in the lack of substrate, although keeping irreversible modifications with respect to the native species. The lack of regaining its native structure certainly affects albumin interaction with biological environment. The present investigation on the stoichiometric synthetic geoinspired chrysotile nanocrystals is the first approach toward a deeper attempt to use standard synthetic chrysotile reference samples in mimicking the behavior of asbestos fibers and allows to better understand their interaction with a biological environment

Euclid Preparation. XXXVII. Galaxy colour selections with Euclid and ground photometry for cluster weak-lensing analyses

We derived galaxy colour selections from Euclid and ground-based photometry, aiming to accurately define background galaxy samples in cluster weak-lensing analyses. Given any set of photometric bands, we developed a method for the calibration of optimal galaxy colour selections that maximises the selection completeness, given a threshold on purity. We calibrated galaxy selections using simulated ground-based $griz$ and Euclid $Y_{\rm E}J_{\rm E}H_{\rm E}$ photometry. Both selections produce a purity higher than 97%. The $griz$ selection completeness ranges from 30% to 84% in the lens redshift range $z_{\rm l}\in[0.2,0.8]$. With the full $grizY_{\rm E}J_{\rm E}H_{\rm E}$ selection, the completeness improves by up to $25$ percentage points, and the $z_{\rm l}$ range extends up to $z_{\rm l}=1.5$. The calibrated colour selections are stable to changes in the sample limiting magnitudes and redshift, and the selection based on $griz$ bands provides excellent results on real external datasets. The $griz$ selection is also purer at high redshift and more complete at low redshift compared to colour selections found in the literature. We find excellent agreement in terms of purity and completeness between the analysis of an independent, simulated Euclid galaxy catalogue and our calibration sample, except for galaxies at high redshifts, for which we obtain up to 50 percent points higher completeness. The combination of colour and photo-$z$ selections applied to simulated Euclid data yields up to 95% completeness, while the purity decreases down to 92% at high $z_{\rm l}$. We show that the calibrated colour selections provide robust results even when observations from a single band are missing from the ground-based data. Finally, we show that colour selections do not disrupt the shear calibration for stage III surveys.Comment: 20 pages, 13 figures. Published by A&

Biomimetic customized composite scaffolds and translational models for the bone regenerative medicine using CAD-CAM technology

Nature produces soft and hard materials exhibiting remarkable functional properties by controlling the hierarchical assembly of simple molecular building blocks from the nano- to the macro-scale. Biogenic materials are nucleated in defined nano–micro-dimensioned sites inside the biological environments, in which chemistry can be spatially controlled, in order to monitor the size, shape, and structural organization of biomaterials. With the development of nanotechnology, this strategy employing natural material genesis has attracted attention in designing bioinspired materials at the nanoscale dimensions. In this contest, biomimetic nanostructured hydroxyapatite is a promising biomaterial for bone tissue engineering because this material exhibits excellent biological properties. However, hydroxyapatite is still limited as bone substitute due to the brittleness of the material. Hence, a widespread approach is the creation of hybrid materials with an inorganic or organic bioactive phase mimicking functional bony units and a polymeric phase of a consistency permitting the device to be manipulated to achieve an anatomically compatible shape and allowing surface adsorption of molecules that play active roles in the biological environment. Recently, many studies were developed in order to prepare and test new bioengineered custom-made composite scaffold materials using a combination of CAD/CAM technology to restore full-thickness defects of the bone. Modern 3D printing techniques allow dimensioning of the external volume according to the surgical defect, thus simplifying the surgery and reducing biological morbidity. The use of CAD/CAM technology and the novel composite, biomimetic, and resorbable scaffolds are the promising way to interpret the need of bone regenerative medicine

Synthetic Phloroglucinol Surface Protected Se Nanoparticles for Potential Biomedical Applications

The specific anticarcinogenic properties of Se and the phloroglucinol ones have coupled in new amorphous Se nanoparticles, surface capped with phloroglucinol synthesized in mild conditions, which may be used in biomedical field. The phloroglucinol surface protected Se nanoparticles have been synthesised according to a new green method without any organic solvent and using phloroglucinol as reducing and capping agent in order to obtain Se nanoparticles suitable for interesting anticancer biomedical applications. Se nanoparticles reveal an homogeneous dimension of about 2\u20133 nm in diameter and remain stable in dry conditions or if stored in ethanol at room temperature and in darkness. FT-IR investigation reveals that phloroglucinol molecules on the Se nanoparticle surface are linked each other via oxygen atoms bridging adjacent molecules, so forming a surface phloroglucinol coating which prevents Se nanoparticles aggregation. This aggregation in micrometric clusters can be obtained by a heating treatment at 285 C which partially destroy the phloroglucinol surface coating

The Iron-Related Molecular Toxicity Mechanism of Synthetic Asbestos Nanofibres: A Model Study for High-Aspect-Ratio Nanoparticles

Asbestos shares with carbon nanotubes some morphological and physico-chemical features. An asbestos-like behaviour has been recently reported by some authors, though the mechanism of toxicity may be very different. To identify at the atomic level the source of toxicity in asbestos, the effect of progressive iron loading on a synthetic iron-free model nanofibre previously found non-toxic in cellular tests was studied. A set of five synthetic chrysotile nanofibres [(Mg,Fe)3(Si2O5)(OH)4] has been prepared with Fe ranging from 0 to 1.78\u2005wt\u2009%. The relationship between fibre-induced free-radical generation and the physico-chemical characteristics of iron active sites was investigated with spin-trapping techniques on an aqueous suspension of the fibres and M\uf6ssbauer and EPR spectroscopies on the solids, respectively. The fully iron-free fibre was inert, whereas radical activity arose with even the smallest amount of iron. Surprisingly, such activity decreased upon increasing iron loading. M\uf6ssbauer and EPR revealed isolated iron ions in octahedral sites that undergo both axial and rhombic distortion and the occurrence of aggregated iron ions and/or extra-framework clustering. The isolated ions largely prevailed at the lowest loadings. Upon increasing the loading, the amount of isolated iron was reduced and the aggregation increased. A linear relationship between the formation of carbon-centred radicals and the amount of rhombic-distorted isolated iron sites was found. Even the smallest iron contamination imparts radical reactivity, hence toxicity, to any chrysotile outcrop, thereby discouraging the search for non-toxic chrysotile. The use of model solids that only differ in one property at a time appears to be the most successful approach for a molecular understanding of the physico-chemical determinants of toxicity. Such findings could also be useful in the design of safer nanofibres

From wood to bone: multi-step process to convert wood hierarchical structures into biomimetic hydroxyapatite scaffolds for bone tissue engineering

Hydroxyapatite (HA) bone scaffolds characterized by highly organized hierarchical structures have been obtained by chemically transforming native woods through a sequence of thermal and hydrothermal processes. The whole chemical conversion has been carried out through five steps from native wood to porous hydroxyapatite: 1) pyrolysis of ligneous raw materials to produce carbon templates characterized by the natural complex anisotropic pore structure; 2) carburization process by vapour or liquid calcium permeation to yield calcium carbide; 3) oxidation process to transform calcium carbide into calcium oxide; 4) carbonation by hydrothermal process under CO2 pressure for the further conversion into calcium carbonate; 5) phosphatization process through hydrothermal treatment to achieve the final hydroxyapatite phase. The five steps of the phase transformation process have been set up in order to achieve total phase conversion and purity maintaining the original native microstructure. An innovative biomimetic apatite hierarchically structured in parallel fastened hollow microtubules has been synthesized, structurally characterized and proposed as a new inorganic biomorphic scaffold providing a biomimetic nanostructure surface for fascinating bone engineering applications

Asbestos health hazard: A spectroscopic study of synthetic geoinspired Fe-doped chrysotile.

The chrysotile fibres toxicity appears correlated to the redox activity of iron present in the chrysotile structure. In fact the generation of reactive oxygen species and other radicals appears catalyzed by iron ions and closely related to Fe ions organization in specific crystallographic sites having a capability to activate free radical generation. The Fe substitution to Mg and/or Si in the chrysotile structure appears important for asbestos health hazard investigation. Infrared and Raman spectroscopic analyses have been utilized to investigateMg and/or Si ions replacement by Fe ions in chrysotile structure as a function of the Fe doping extent. Geoinspired synthetic chrysotile at different Fe doping extents has been obtained as unique phase by hydrothermal reaction in the presence or not ofmetallic Fe in the synthetic environment. The results highlight that Fe can replace both Mg and Si, differently modifying the chrysotile structure as a function of the Fe doping extent and the Fe doping process. The contemporary iron substitution into the octahedral and tetrahedral sheets reveals an appreciable increase of the dehydroxylation temperature which occurs at higher temperature than for iron-free sample. The results highlight the role of Fe substitution in the asbestos structure influencing the health hazard of biological systems