Photoluminescence spectroscopy of YVO4:Eu3+ nanoparticles with aromatic linker molecules: A precursor to biomedical functionalization.

Photoluminescence spectra of YVO₄:Eu³⁺ nanoparticles are presented, with and without the attachment of organic molecules that are proposed for linking to biomolecules. YVO₄:Eu³⁺ nanoparticles with 5% dopant concentration were synthesized via wet chemical synthesis. X-ray diffraction and transmission electron microscopy show the expected wakefieldite structure of tetragonal particles with an average size of 17 nm. Fourier-transform infrared spectroscopy determines that metal-carboxylate coordination is successful in replacing native metal-hydroxyl bonds with three organic linkers, namely, benzoic acid, 3-nitro 4-chloro-benzoic acid, and 3,4-dihydroxybenzoic acid, in separate treatments. UV-excitation photoluminescence spectra show that the position and intensity of the dominant ⁵D₀ - ⁷F₂ electric-dipole transition at 619 nm are unaffected by the benzoic acid and 3-nitro 4-chloro-benzoic acid treatments. Attachment of 3,4-dihydroxybenzoic acid produces an order-of-magnitude quenching in the photoluminescence, due to the presence of high-frequency vibrational modes in the linker. Ratios of the dominant electric- and magnetic-dipole transitions confirm infrared measurements, which indicate that the bulk crystal of the nanoparticle is unchanged by all three treatments. [ABSTRACT FROM AUTHOR]