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

[Display omitted] •Tb3+/Sm3+ co doped hydroxyapatite nanoparticles were prepared by chemical precipitation method.•The energy transfer from the sensitiser Tb3+ to the activator Sm3+ ions was studied.•The MTT cell viability assay confirmed the least cytotoxic nature of the synthesised nanoparticles.•The cellular uptake of the nanoparticle in N2a cells was confirmed by fluorescent microscopy. 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.