RESUMO
The effect of novel silver nanowire encapsulated NaGdF4:Yb,Er hybrid nanocomposite on the upconversion emission and bioimaging properties has been investigated. The upconvension nanomaterials were synthesised by polyol method in the presence of ethylene glycol, PVP and ethylenediamine. The NaGdF4:Yb,Er-Ag hybrid was formed with upconverting NaGdF4:Yb,Er nanoparticles of size ~ 80 nm and silver nanowires of thickness ~ 30 nm. The surface plasmon induced by the silver ion in the NaGdF4:Yb,Er-Ag nanocomposite resulted an intense upconversion green emission at 520 nm and red emission at 660 nm by NIR diode laser excitation at 980 nm wavelength. The UV-Vis-NIR spectral absorption at 440 nm and 980 nm, the intense Raman vibrational modes and the strong upconversion emission results altogether confirm the localised surface plasmon resonance effect of silver ion in the hybrid nanocomposite. MRI study of both NaGdF4:Yb,Er nanoparticle and NaGdF4:Yb,Er-Ag nanocomposite revealed the T1 relaxivities of 22.13 and 10.39 mM-1 s-1, which are larger than the commercial Gd-DOTA contrast agent of 3.08 mM-1 s-1. CT imaging NaGdF4:Yb,Er-Ag and NaGdF4:Yb,Er respectively showed the values of 53.29 HU L/g and 39.51 HU L/g, which are higher than 25.78 HU L/g of the CT contrast agent Iobitridol. The NaGdF4:Yb,Er and NaGdF4:Yb,Er-Ag respectively demonstrated a negative zeta potential of 54 mV and 55 mV, that could be useful for biological application. The in vitro cytotoxicity of the NaGdF4:Yb,Er tested in HeLa and MCF-7 cancer cell line by MTT assay demonstrated a cell viability of 90 and 80 %, respectively. But, the cell viability of NaGdF4:Yb,Er-Ag slightly decreased to 80 and 78%. The confocal microscopy imaging showed that the UCNPs are effectively up-taken inside the nucleolus of the cancer cells, and it might be useful for NIR laser-assisted phototherapy for cancer treatment. Graphical abstract.
Assuntos
Meios de Contraste/química , Corantes Fluorescentes/química , Fluoretos/química , Gadolínio/química , Nanocompostos/química , Nanofios/química , Linhagem Celular Tumoral , Meios de Contraste/efeitos da radiação , Érbio/química , Érbio/efeitos da radiação , Corantes Fluorescentes/efeitos da radiação , Fluoretos/efeitos da radiação , Gadolínio/efeitos da radiação , Humanos , Imageamento por Ressonância Magnética , Nanopartículas Metálicas/química , Nanopartículas Metálicas/efeitos da radiação , Microscopia Confocal , Microscopia de Fluorescência , Nanocompostos/efeitos da radiação , Nanofios/efeitos da radiação , Prata/química , Prata/efeitos da radiação , Tomografia Computadorizada por Raios X , Itérbio/química , Itérbio/efeitos da radiaçãoRESUMO
Uniform Gd2O3 : Eu3+ nanowires were fabricated by using anodic aluminum oxide template (AAO). The spectral measurements indicate that with the increasing annealing temperature the excitation band of Eu3+ in Gd2O3 : Eu3+ nanowires/AAO shifted blue, the intensity ratio of 5D0-7F2 to 5D0-7F1, decreased, and the lifetime became longer. In the sample annealed at 1000 degrees C two spectral components, the sharper and broader lines were identified, corresponding to two different local environments, the Eu3+ ions in cubic phase and in amorphous phase, respectively. The 5D0-7F1 transitions of Eu3+ ions in cubic phase had longer lifetime than that in amorphous phase. In contrast to the lifetime of the 5D0-7F(j) transitions in the bulk, that in Gd2O3 : Eu3+/AAO composite films increased due to influence of the surrounding media (AAO).