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Open Readings 2023 • O2-4
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ENHANCED BIOIMAGINING PROPERTIES OF NANOSIZED FLUOROAPATITE COMPOSITES, DOPED WITH EUROPIUM(III) IONS VIA INCORPOTARTION OF RUBIDIUM(I) IONS

Nicole Nowak1, 2, Dominika Czekanowska1, Tomasz Gebarowski2, Rafal J. Wiglusz1

1 Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okolna 2, PL-50-422 Wroclaw, Poland

2 Department of Animal Biostructure and Physiology, Wroclaw University of Environmental and Life Sciences, Norwida 25, PL-50-375 Wroclaw, Poland

[email protected]

Europium is the rarest element among the lanthanides and yet the most reactive one. Europium element has two different oxidation states +2 and +3 with the electronic configuration [Xe]4f6 and [Xe]4f7, respectively. It is easier to obtain inorganic materials doped with europium with +3 oxidation state than with the oxidation state +2, which relates to reductive synthesis conditions. Despite the high reactivity of europium element, it has also interesting luminescence properties. The Eu3+ ions emit strong red-orange visible light exciting in the UV range of energy for the electromagnetic spectrum. [1]. Therefore, this ion can be used as a sensitive luminescence probe. Moreover, many studies confirmed the highly biocompatible properties of inorganic composites based on calcium phosphate compounds doped with Eu3+ ions [2].

Synthetic apatites are widely used in biomedical field, as a bone or teeth fillers, due to their highly developed specific surface and ability to develop stable bond with living tissues. Fluorapatites have particular advantage over hydroxyapatites via their structural stability and more resistant for demineralization process that occurs in the bone tissue. Hence, fluorapatites can be more suitable substitution for hydroxyapatite in biomedical uses [3].

Rubidium as a trace element can occur in the low concentration in human teeth. However, it seems to have valuable biological features. Interestingly, many studies confirmed biocompatibility of Rb+ ions and their positive effect on osteo- and chondrogenesis. Moreover, by its similarity to lithium ions it also exhibits antidepressant properties [4].

Our research team developed highly stable two series of fluorapatite compounds co-doped with Eu3+ ions and various concentration of Rb+ ions (1, 3, 5, 7 mol%). Structure and morphology were investigated via X-ray powder diffraction technique (XRPD), infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). Luminescence properties were evaluated by measuring emission and excitation spectra but also by luminescence kinetics. Finally, to evaluate biological properties obtained nanomaterials were tested toward NHDF. Additionally, immune response was evaluated by testing materials toward THP-1 macrophage cell line.

Figure 1
Fig. 1. TEM and life time and image of obtained fluoroapatite based compounds co-doped with Eu3+ and Rb+ ions.

[1] Binnemans, K. (2015). Interpretation of europium(III) spectra. Coordination Chemistry Reviews, 295, 1–45.

[2] K. Melcher, L.-M. Ng, E. Zhou et al., A gate-latch-lock mechanism for hormone signaling by abscisic acid receptors, Nature 462, 602-608 (1990). Di, W., Li, J., Shirahata, N., Sakka, Y., Willinger, M. G., & Pinna, N. (2011). Photoluminescence, cytotoxicity and in vitro imaging of hexagonal terbium phosphate nanoparticles doped with europium. Nanoscale, 3(3), 1263–1269.

[3] Abou Neel EA; Aljabo A; Strange A; Ibrahim S; Coathup M; Young AM; Bozec L; Mudera V. Demineralization-Remineralization Dynamics in Teeth and Bone. Int J Nanomedicine 2016, 11, 4735–4741

[4] Nowak, N., Czekanowska, D., Reeks, J. M., & Wiglusz, R. J. (2022). Structural, Spectroscopic, and Biological Characterization of Novel Rubidium(I) and Europium(III) Co-Doped Nano-Hydroxyapatite Materials and Their Potential Use in Regenerative Medicine. Nanomaterials, 12(24), 4475.