Eu3+ and Tb3+doped apatite nanoparticles prepared by hydrothermal transformation of oyster shells calcium carbonate. Solid-state, luminescence, and in vitro biological characterization

Oyster shell wastes from the fishing industry represent a major environmental problem, as 7 million Tm/year are produced with no efficient recycling [1]. They are composed of Mgcalcite embedded in an organic matrix formed of proteins and polysaccharides. On the other hand, nanocrystalline apatites (NAp), which are structural and compositional analogues to the major inorganic component of human bones, exhibit excellent bioactivity and biocompatibility, and present a broad range of applications in hard tissue engineering, biomedicine, drug-delivery system and even in analytical sciences [2]. In this work, biogenic calcite from oyster shells was used to obtain apatite NPs by a ¿one-pot¿ hydrothermal process. Eu3+ and Tb3+ ions were added to the formulation to obtain Eu3+- and Tb3+-doped apatite NPs with luminescent properties. Solid-state characterization of the nanoparticles was performed by powder X-ray diffraction (PXRD), FT-IR and Raman spectroscopy, SEM and TEM microscopy, dynamic light scattering (DLS) and inductively coupled plasma (ICP) spectrometry, while luminescence properties were evaluated by luminescent spectroscopy. Finally, the biological behaviour of the NPs was evaluated by cytotoxicity and osteogenic differentiation assays, in murine mesenchymal (M17.1) and murine endothelial (MS-1) cells. Results demonstrated the efficiency of this novel ¿one pot¿ hydrothermal process to obtain nanoparticles of apatite with improved luminescent properties, while, in vitro assays demonstrated the excellent cytocompatibility and the impact of the metal-doping over the osteogenic differentiation capacity of the nanoparticles. Acknowledgment: This work was supported by project PCI2020-112108 funded by MCI/AEI/10.13039/501100011033 (Spain) and the European Union ¿NextGenerationEU¿/PRTR¿. PCI2020-112108 is part of the CASEAWA project of the ERA-NET Cofund BlueBio Programme, supported by the European Union (H2020).