Au@NaYF₄:Tb³⁺ core@shell nanostructures: Synthesis and construction of luminescence resonance energy transfer

Luminescence resonance energy transfer (LRET) system can be constructed using NaYF₄:Tb³⁺ luminescence nanocrystals and gold nanoparticles (AuNPs) served as energy donor and acceptor, respectively. The AuNPs modified by cetyltrimethylammonium bromide (CTAB) were synthesized first and NaYF₄:Tb³⁺ shells encapsulated Au cores via a hydrothermal method. The synthesized materials were well characterized by X-ray diffraction (XRD), Fourier-transform infrared spectra (FT-IR), Transmission electron microscopy (TEM), X-ray photoelectron spectrum (XPS), UV–vis absorption spectra (UV–vis) and photoluminescence (PL) measurement. The results indicate that the synthesized Au@NaYF₄:Tb³⁺ core–shell nanoparticles have spherical morphology with a size of 80–90 nm and the shell layers of NaYF₄:Tb³⁺ nanocrystals have pure cubic structure. The luminescence properties of Au@NaYF₄:Tb³⁺ core–shell nanoparticles are same as those of NaYF₄:Tb³⁺ particles. The LRET process was realized using the core–shell nanoarchitectures due to the absorption spectrum of AuNPs matches well with the major emission peaks of Tb³⁺ ions. The LRET experiments have successfully verified the energy transfer between NaYF₄:Tb³⁺ nanocrystals and AuNPs. Additionally, the emission intensities of Tb³⁺ ions and the content of AuNPs exhibited a fair linear correlation.