Cowries derived aragonite as raw biomaterials for bone regenerative medicine.

Carbonate apatites are sought as a bone substitute due to their biocompatibility and excellent resorbability. The present study deals with Cowrie's shell derived powder (CSDP) as natural biomaterial for bone regenerative medicine. Structural and physicochemical analysis showed that Cowrie's shells, presenting brick and mortar microstructures, were mainly composed of aragonite crystals, which were converted into poorly crystalline B-type carbonate apatite once soaked, at 37 °C, in simulated body fluid for 7 days, reflecting bioactive features. Cytotoxic assays showed that CSDP boosted human stem cell proliferation over the study time compared to nacre derived powder (NDP), used as positive control. Human stem cells adopted a flattened morphology and established physical contact with CSDP, signature of a good biocompatibility. Thus, these results suggested that CSDP presents a great interest for bone regenerative medicine, and could be a useful and versatile carrier/scaffold for bone tissue engineering or a raw material for 3D printed orthopedic devices.

Using synthetic models to simulate aging of Cu contamination in soils.

The Bureau Commun de Référence (BCR) sequential extraction scheme and micro-synchrotron-based X-ray fluorescence (µ-SXRF) analysis were used to determine the Cu fractionation in a calcareous vineyard soil and a synthetic soil (mixture of seven constituents: calcite, birnessite, ferrihydrite, goethite, lignocellulosic residue, kaolinite, and quartz) at different Cu contamination rates (190, 1270, and 6350 mg kg(-1) of Cu) and aging times (1, 30, 92, and 181 days). The Cu distribution in the spiked vineyard and synthetic soils was different from the original vineyard one and was influenced by the loading level. The newly added Cu was preferentially present in the acid soluble fraction. Aging of the contaminated vineyard and synthetic soils during 6 months led to the redistribution of Cu from the weakly bound acid soluble fraction to the strongly bound reducible one. The evolution with time could satisfactorily be simulated by the Elovich diffusion model for the synthetic soils. It was less significant as less marked in the contaminated vineyard soil than in the synthetic one, even though the trends observed in both were similar. This study supported the hypothesis that "simple" synthetic models could be used to approach the Cu fractionation and its evolution with time in vineyard soils.