Ultra-small CaF2:Ln3+ nanoparticle fluorescent probes for detection of tumor markers TR-FRET and targeted imaging of tumor cells
Rare-earth-doped inorganic nanocrystals have the advantages of high photochemical stability, almost no toxicity, narrow linewidth, long fluorescence lifetime, high luminous efficiency, and tunable fluorescence emission wavelength, and are currently a promising new generation of fluorescent biomarker materials. However, fluorescent biomarker materials have extremely high requirements on the luminescence, size, water solubility and biosafety of nanocrystals. In particular, in vivo imaging and fluorescence resonance energy transfer (FRET) immunoassay applications require nanocrystals. Both efficient light emission and ultra-small size (<10 nm). As a highly efficient rare earth doped matrix material, CaF2 has excellent biocompatibility. However, due to the heterovalent doping of rare earth ions and the surface fluorescence quenching effect, it is still a technical problem to prepare ultra-small and efficient rare earth doped CaF2 nanocrystals.
Under the support of the “863” Program of the Ministry of Science and Technology and the Major Scientific Instrument Development Project, the National Natural Science Foundation, and the “Hundred Talents Program” of the Chinese Academy of Sciences, the Chen Xueyuan Research Group and the National Key to Structural Chemistry of the Key Laboratory of Optoelectronic Materials Chemistry and Physics of the Fujian Institute of Materials Structure, Chinese Academy of Sciences In the laboratory, Huang Mingdong's research team cooperated to synthesize monodisperse CaF2:Ln 3+ with a particle size of less than 10 nm and its core-shell structure nanocrystals by high-temperature coprecipitation using the sodium ion co-doping technique.
The co-doping of sodium ions significantly improves the crystallization and luminescence properties of the nanocrystals. At the same time, the ultra-small (~3.8nm) CaF2:Ce, Tb nanocrystals exhibit anomalously sharp spectral line splitting and elongated fluorescence lifetimes. ~12 ms). The surface-modified nanocrystals can be used as a time-resolved (TR) fluorescent bioprobe to achieve highly sensitive specific detection of biomolecules. For example, in the TRPL heterophasic detection and TR-FRET homogeneous detection, the detection limit of the avidin protein reached 48 and 164 pM, respectively, which is the best record in the rare earth nanocrystal time-resolved fluorescent probe reported so far; further The project team used this ultra-small nano fluorescent probe for the first time to detect the tumor marker soluble urokinase receptor (suPAR) with a detection limit of 328 pM. This value is equivalent to the suPAR level in serum of cancer patients; finally, the prepared CaF2 is used: Ln3+ nano-fluorescent probe successfully achieved its up-conversion and down-conversion fluorescence targeting imaging in human lung adenocarcinoma cells. The relevant research results were recently published in German Applied Chemistry (Angew. Chem. Int. Ed. 2013, DOI: 10.1002/anie.201302481).
Previously, the research group has made progress in the controllable synthesis, spectroscopy, and biomedical applications of rare-earth-doped nano-fluorescent marker materials, such as the use of NaYF4:Ce3+/Tb3+ and KGdF4:Tb3+ nano-fluorescence probes, respectively. Homogeneous TR-FRET Detection of Avidin Proteins of 4.8 and 5.5 nM (Angew. Chem. Int. Ed. 2011, 50, 6306; J. Am. Chem. Soc. 2012, 134, 1323); synthesis has a good biologic phase Capacitated 5 nm or so ZrO2:Tb3+ nanocrystals, enabling TR-FRET detection of 3 nM avidin and targeted bioimaging of human lung adenocarcinoma cells (J. Am. Chem. Soc. 2012, 134, 15083 ).
