Dy 2 O 3 -unpurified hydroxyapatite: a promising thermoluminescent sensor and biomimetic nanotherapeutic

In the present work, nanostructured hydroxyapatite (nano-Hap) was synthesized by following a hydrothermal process using calcium hydroxide and ammonium phosphate. The nano-Hap was unpurified with different amounts of dysprosium oxide (Dy 2 O 3 ), from 0.5 to 2.0 wt%. Its physicochemical properties were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). TEM confirmed the formation of rod structures (L/D aspect ratio > 1) with average sizes ranging from ~ 15 to 19 nm in diameter, and ~ 26 to 32 nm in length. The presence of the monoclinic and hexagonal crystalline phases of Hap was confirmed by XRD. The thermoluminescence (TL) studies showed a linear relationship between the Dy 2 O 3 concentration and TL intensity induced by gamma radiation in a dose range from 10 to 200 Gy. The nano-Hap unpurified with 2.0 wt% of Dy 2 O 3 showed the highest TL response. Additionally, in the perspective of exploring the therapeutic potential of Dy 2 O 3 -unpurified Hap, the viability of human prostatic epithelial cells was evaluated. The safety of pure Hap was confirmed by performing resazurin/resorufin fluorescence-based assays. A significant toxicity was observed as a function of the impurity content and nanopowders concentration. In summary, the nano-Hap TL results make it a good candidate for ionizing radiation sensoring and, the in vitro test encourages the development of a biomimetic Dy-Hap drug-free nanotherapeutic platform.