Preparation And Application Of Multicolor Luminescent Lanthanide Nanoparticles

Time-resolved fluorescence(TRF) bioassay technique based on long-lived fluorescence of lanthanide probes is an ultrasenstive bioanalytical method,and has been widely used in clinical diagnostics and biotechnology.Because strongly fluorescent lanthanide compounds are mainly limited to Eu³⁺ and Tb³⁺ compounds with red(Eu,～615 nm) and green(Tb,～545 nm) emissions,the development and application of fluorescence bioassay technique using lanthanide-based multicolor fluorescent biolabels are rarely investigated.In this work,a series of lanthanide complexes-bound silica nanoparticles with red, orange,yellow and green fluorescence colors was prepared by co-binding different ratios of Eu³⁺/Tb³⁺ fluorescent complexes with the ligand(4'-phenyl-2,2':6',2"-terpyridine-6,6"-diyl) bis(methylenenitrilo) tetrakis(acetic acid) inside the silica nanoparticles.Characterizations by transmission electron microscopy and fluorometric methods indicate that the nanoparticles are spherical and uniform in size with long fluorescence lifetimes(＞1.0 ms) and high photostabilities.The nanoparticle-labeled streptavidin was prepared and used for time-resolved fluoroimmunoassay of human prostate-specific antigen(PSA).The method gives a detection limit of 0.21 ng/mL for human PSA,showing that the nanoparticle-labeled streptavidin still has a good bio-reactivity.The nanoparticle-labeled streptavidin was further used for time-resolved fluorescence imaging detection of an environmental pathogen,Giardia lamblia, in the water samples.The results indicate that the new nanoparticles are useful multicolor fluorescent biolabels for time-resolved fluorescence bioassays...