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Multicolored and white-light phosphors based on doped GdF₃ nanoparticles and their potential bio-applications

Sayed, Farheen N., Grover, V., Sudarsan, V., Pandey, B.N., Asthana, A., Vatsa, R.K., Tyagi, A.K.
Journal of colloid and interface science 2012 v.367 no.1 pp. 161-170
X-ray diffraction, breast neoplasms, color, confocal microscopy, energy efficiency, energy transfer, ethylene glycol, fluorescence, gadolinium, humans, ions, nanocrystals, nanoparticles, neoplasm cells, optical properties, solvents, temperature, white light
Rare-earth-doped gadolinium fluoride nanocrystals were synthesized by a single step synthesis employing ethylene glycol as solvent. Based on X-ray diffraction studies, stabilization of hexagonal modification of GdF₃ has been inferred. The microscopic studies show formation of uniformly distributed nanocrystals (∼15nm). The nanoparticles are readily dispersible in water and show bright luminescence in colloidal solution. The luminescence properties have been investigated as a function of activator concentrations, and enhanced optical properties have been attributed to efficient energy transfer from the Gd³⁺ to the activator RE³⁺ ions, which has further been confirmed by steady-state and time-resolved optical studies. It has been demonstrated that on doping appropriate amount of activators in host GdF₃, a novel white-light-emitting phosphor is obtained with CIE co-ordinates and correlated color temperature (CCT) very close to broad daylight. This can have promising applications as phosphor for white-light ultraviolet-light-emitting diodes (UV-LEDs). Our experiments showed efficient labeling of human breast carcinoma cells (MCF-7) by Tb³⁺-doped GdF₃ nanoparticles. The fluorescence intensity was found to be dependent on the surface modifying/coating agent, and the results were validated using confocal microscopy in terms of localization of these functionalized nanoparticles.