Refluxing Synthesis, Photoluminescence and Binding Ability to Deoxyribonucleic Acid of Water-Soluble Rare Earth Ion-Doped LaF₃ Nanoparticles

Water-soluble rare earth ion (Ce³⁺, Tb³⁺)-doped LaF₃ nanoparticles with the ability to bind to deoxyribonucleic acid (DNA) were prepared by the refluxing method in a glycerol/water mixture and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and so on. The obtained LaF₃:Ce³⁺, LaF₃:Tb³⁺ and LaF₃:Ce³⁺, Tb³⁺ nanoparticles are well crystallized with a hexagonal structure and composed of spherical particles with an average size from 11 to 19 nm. The as-prepared samples can be dispersed into water to form a colloidal solution. Under ultraviolet (UV) light irradiation, the emission lines of Tb³⁺ in the co-doped LaF₃:Ce³⁺, Tb³⁺ are evidently strengthened compared to those in the single-doped LaF₃:Tb³⁺ nanoparticles, which is due to the energy transfer from Ce³⁺ to Tb³⁺ ions in the LaF₃:Ce³⁺, Tb³⁺ samples. The biological experiment confirms that the water-soluble LaF₃:Ce³⁺, Tb³⁺ nanoparticles can be bonded to the DNA molecules and emit visible light under UV irradiation. These luminescent nanoparticles could be used similarly to ethidium bromide (EtBr), which has been used extensively as a DNA staining reagent. The advantage that LaF₃:Ce³⁺, Tb³⁺ nanoparticles have lower toxicity than EtBr makes them a potential reagent instead of EtBr in the DNA staining in biological experiments.