Preparation of a novel fluorescence probe of terbium-europium co-luminescence composite nanoparticles and its application in the determination of proteins

Terbium-europium Tb-Eu/acetylacetone(acac)/poly(acrylamide) (PAM) co-luminescence composite nanoparticles were successfully prepared using the ultrasonic approach. The as-prepared composite nanoparticles show the characteristic emission spectra of Tb³⁺, located at 496 and 549 nm. Furthermore, the nanoparticles are water soluble, stable and have extremely narrow emission bands and high internal fluorescence quantum yield due to the co-luminescence effect. Further studies indicate that proteins can interact with the nanoparticles and induce the fluorescence quenching of the nanoparticles. Based on the fluorescence quenching of nanopaticles in the presence of proteins, a novel method for the sensitive determination of trace amounts of proteins was proposed. Under the optimal experimental conditions, the linear ranges of calibration curves are 0-3.5 μg mL⁻¹ for human serum albumin (HSA) and 0-4.0 μg mL⁻¹ for γ-globulin (γ−IgG), respectively. The limits of detection are 7.1 for HSA and 6.7ng mL⁻¹ for γ−IgG, respectively. The method was applied to the quantification of proteins in synthetic samples and actual human serum samples with satisfactory results. This proposed method is sensitive, simple and has potential application in the clinical assay of proteins.