Toward Smart Biomimetic Apatite-Based Bone Scaffolds with Spatially Controlled Ion Substitutions.

Biomimetic apatites exhibit a high reactivity allowing ion substitutions to modulate their in vivo response. We developed a novel approach combining several bioactive ions in a spatially controlled way in view of subsequent releases to address the sequence of events occurring after implantation, including potential microorganisms' colonization. Innovative micron-sized core-shell particles were designed with an external shell enriched with an antibacterial ion and an internal core substituted with a pro-angiogenic or osteogenic ion. After developing the proof of concept, two ions were particularly considered, Ag+ in the outer shell and Cu2+ in the inner core. In vitro evaluations confirmed the cytocompatibility through Ag-/Cu-substituting and the antibacterial properties provided by Ag+. Then, these multifunctional "smart" particles were embedded in a polymeric matrix by freeze-casting to prepare 3D porous scaffolds for bone engineering. This approach envisions the development of a new generation of scaffolds with tailored sequential properties for optimal bone regeneration.

PET plastics as a Trojan horse for radionuclides.

Mismanaged plastic waste interacts with secondary environmental pollutants, potentially aggravating their impact on ecosystems and human health. Here we characterized the natural and artificial radionuclides in polyethylene terephthalate (PET) bottles collected from the industrial littoral discharge of a phosphate fertilizer plant. The activity concentrations in littered bottles ranged from 0.47 (208Tl) to 12.70 Bq·kg-1 (226Ra), with a mean value of 5.30 Bq·kg-1. All the human health risk assessment indices (annual intake, annual effective dose, and excess lifetime cancer risk) estimated for radionuclides associated with ingestion and inhalation of microplastics were below international safety limits. Our results demonstrated that PET can be loaded with natural and artificial radionuclides, and potentially act as a carrier to transfer radionuclides to humans, posing a new potential health risk. Increased use, mismanagement and fragmentation of plastic waste, and continued interaction of plastic waste with radioelements may lead to enhanced radiation exposure in the future.

Influence of process parameters on energetic properties of sputter-deposited Al/CuO reactive multilayers.

In this study, we demonstrate the effect of change of the sputtering power and the deposition pressure on the ignition and the combustion properties of Al/CuO reactive thin films. A reduced sputtering power of Al along with the deposition carried out at a higher-pressure result in a high-quality thin film showing a 200% improvement in the burn rate and a 50% drop in the ignition energy. This highlights the direct implication of the change of the process parameters on the responsivity and the reactivity of the reactive film while maintaining the Al and CuO thin-film integrity both crystallographically and chemically. Atomically resolved structural and chemical analyzes enabled us to qualitatively determine how the microstructural differences at the interface (thickness, stress level, delamination at high temperatures and intermixing) facilitate the Al and O migrations and impact the overall nano-thermite reactivity. We found that the deposition of CuO under low pressure produces well-defined and similar Al-CuO and CuO-Al interfaces with the least expected intermixing. Our investigations also showed that the magnitude of residual stress induced during the deposition plays a decisive role in influencing the overall nano-thermite reactivity. Higher is the magnitude of the tensile residual stress induced, stronger is the presence of gaseous oxygen at the interface. By contrast, high compressive interfacial stress aids in preserving the Al atoms for the main reaction while not getting expended in the interface thickening. Overall, this analysis helped in understanding the effect of change of deposition conditions on the reactivity of Al/CuO nanolaminates and several handles that may be pulled to optimize the process better by means of physical engineering of the interfaces.

Structural evidence for a new elaborate 3D-organization of the cardiomyocyte lateral membrane in adult mammalian cardiac tissues.

AIMS: This study explored the lateral crest structures of adult cardiomyocytes (CMs) within healthy and diseased cardiac tissue. METHODS AND RESULTS: Using high-resolution electron and atomic force microscopy, we performed an exhaustive quantitative analysis of the three-dimensional (3D) structure of the CM lateral surface in different cardiac compartments from various mammalian species (mouse, rat, cow, and human) and determined the technical pitfalls that limit its observation. Although crests were observed in nearly all CMs from all heart compartments in all species, we showed that their heights, dictated by the subsarcolemmal mitochondria number, substantially differ between compartments from one species to another and tightly correlate with the sarcomere length. Differences in crest heights also exist between species; for example, the similar cardiac compartments in cows and humans exhibit higher crests than rodents. Unexpectedly, we found that lateral surface crests establish tight junctional contacts with crests from neighbouring CMs. Consistently, super-resolution SIM or STED-based immunofluorescence imaging of the cardiac tissue revealed intermittent claudin-5-claudin-5 interactions in trans via their extracellular part and crossing the basement membrane. Finally, we found a loss of crest structures and crest-crest contacts in diseased human CMs and in an experimental mouse model of left ventricle barometric overload. CONCLUSION: Overall, these results provide the first evidence for the existence of differential CM surface crests in the cardiac tissue as well as the existence of CM-CM direct physical contacts at their lateral face through crest-crest interactions. We propose a model in which this specific 3D organization of the CM lateral membrane ensures the myofibril/myofiber alignment and the overall cardiac tissue cohesion. A potential role in the control of sarcomere relaxation and of diastolic ventricular dysfunction is also discussed. Whether the loss of CM surface crests constitutes an initial and common event leading to the CM degeneration and the setting of heart failure will need further investigation.

Characterization of phosphate rock and phosphogypsum from Gabes phosphate fertilizer factories (SE Tunisia): high mining potential and implications for environmental protection.

Since the establishment of the coastal industrial complex in Gabes city (Gulf of Gabes, SE Tunisia), hundred million tons of untreated phosphogypsum have been discharged in the open sea causing serious environmental problems. To better understand the dynamic and behavior of phosphate/phosphogypsum contaminants from raw ores to marine environment, a chemical, organic, mineralogical, and morphological characterization of phosphate rock and phosphogypsum was conducted using several sophisticated techniques. The chemical analysis showed that phosphate and phosphogypsum contain high loads of trace elements and that the transfer factors of pollutants varied from 5.83% (U) to 140% (Hg). Estimated annual flows of phosphogypsum contaminants into the marine environment ranged between 0.05 (Re) and 87,249.60 (F) tons. The phosphate rock was found to be formed by carbonate fluorapatite, calcite, dolomite, natural gypsum, quartz, calcite-Mg, apatite, pyrite, fluorite, and sphalerite-Cd and phosphogypsum by synthetic gypsum and sphalerite-Cd. The phosphate was found to be richer in organic compounds compared to phosphogypsum. Based on this work, the Tunisian phosphogypsum has a high mining potential and encourages the development of an economically beneficial and environmentally friendly phosphogypsum-treating industry.