Structural and optical properties of dysprosium doped hydroxyapatite nanoparticles and its bioimaging probe in human cells

Luminescent Tb3+/Sm3+ co-doped hydroxyapatite nanoparticles as an imaging probe in N2a cells

This work reports the synthesis of hydroxyapatite (HAp) nanoparticles co-doped with trivalent terbium (Tb3+) and samarium (Sm3+) ions by a surfactant free chemical precipitation method. Co-doping enables to combine the optical properties of Tb3+ and Sm3+ ions. Characterization techniques like X-Ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, inductively coupled plasma-optical emission spectroscopy (ICP-OES), energy dispersive X-ray spectroscopy (EDX) were used to determine the crystalline and structural properties. These studies confirmed that the lanthanide ions Tb3+ and Sm3+ were successfully doped onto the HAp lattice. The photoluminescence emission spectra exhibited intense emissions from both the lanthanide ions. The Sm3+ photoluminescence spectra showed enhanced emission,indicating that energy is being transferred from the Tb3+ to Sm3+ ions. To examine the cell viability, N2a cellswere subjected to the MTT cytotoxicity assay. As demonstrated by the cell imaging on N2a cells, the synthesised nanoparticles are ideal candidates for fluorescent labelling using lanthanide ions. Furthermore, thestrong cytocompatibility of Tb3+/Sm3+ co-doped hydroxyapatitesuggests that it is a promising nanoscale biomaterial.

Lanthanides-Substituted Hydroxyapatite for Biomedical Applications

Lately, there has been an increasing demand for materials that could improve tissue regenerative therapies and provide antimicrobial effects. Similarly, there is a growing need to develop or modify biomaterials for the diagnosis and treatment of different pathologies. In this scenario, hydroxyapatite (HAp) appears as a bioceramic with extended functionalities. Nevertheless, there are certain disadvantages related to the mechanical properties and lack of antimicrobial capacity. To circumvent them, the doping of HAp with a variety of cationic ions is emerging as a good alterative due to the different biological roles of each ion. Among many elements, lanthanides are understudied despite their great potential in the biomedical field. For this reason, the present review focuses on the biological benefits of lanthanides and how their incorporation into HAp can alter its morphology and physical properties. A comprehensive section of the applications of lanthanides-substituted HAp nanoparticles (HAp NPs) is presented to unveil the potential biomedical uses of these systems. Finally, the need to study the tolerable and non-toxic percentages of substitution with these elements is highlighted.