Preparation And Applications Of Rare-Earth-Doped Luminescent Nanomaterials:Upconversion Luminescence Cell Imaging And Highly Selective Detection Of PAHs

Compared with organic dyes and fluorescent quantum dots, rare-earth-doped upconversion luminescence nanomaterials(UCNPs) have received great attention owing to their potential advantages. Recent research has achieved considerable success in synthesizing UCNPs for applications. This work was devoted to the prepatation of rare earth luminescence nanomaterials and applications in the field of upconversion lumineceence cell imaging and selective detection of polycyclic aromatic hydrocarbons (PAHs)First, multicolor rare-earth-doped upconversion (UC) luminescence of NaYF4:Yb3+/Er3+nanoparticles (NPs) were successfully tuned by simply controlling the NaF dosage. Unlike the UC nanocrystals with multicolor emission by varying the rare-earth dopants previously reported in the literature, the current work developed a new approach to tune the UC emission color by controlling NaF concentration without changing the ratio and dosage of rare earth ions. To demonstrate their biological applications, the water-stable, biocompatible, and bioconjugatable NaYF4:Yb3+/Er3+@PAA NPs were synthesized by this developed one-step strategy. The influences of reaction temperature and time, the content of NaF, and pH have been investigated for the shape, size and luminescence of the UC luminescent nanocrystals. Also, this new developed materials have been applied for the targeted HeLa cell UC luminescence imaging successfully.Meanwhile, we develop a facile one-pot hydrothermal route to obtain O-carboxymethyl chitosan (OCMC)-wrapped NaYF4:Yb3+/Tm3+/Er3+red UCNPs which have been used for targeted cell luminescence imaging directly and efficiently. The successful coating of the UCNPs by OCMC has been confirmed by Fourier-transform infrared (FTIR) spectroscopy and dynamic light scattering (DLS) studies. Transmission electron microscopy (TEM), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), and photoluminescence (PL) spectra have been used to characterize the size, composition and emission color of the samples, respectively. Due to the good biocompatibility, water-solubility, and strong UC luminescence, these hydrophilic nanocrystals will open up new avenues in further bioapplications.In addition, a facile method is presented for the selective luminescence detection of trace polycyclic aromatic hydrocarbons (PAHs) based on a combination of the specific recognition of molecularly imprinted polymers (MIPs) and magnetic separation. Multifunctional magnetic-luminescent MIP nanocomposites were fabricated via a one-pot emulsion strategy using polystyrene-co-methacrylic acid copolymer, hydrophobic Fe3O4nanoparticles and luminescent LaVO4:Eu3+nanoparticles as building blocks with a phenanthrene template. The resulting nanocomposites can be employed in a simple method for the luminescence detection of phenanthrene. Furthermore, magnetic separation of the nanocomposites from the target mixture prior to luminescence detection of phenanthrene affords significantly enhanced selectivity and sensitivity, with a3a limit of detection (LOD) as low as3.64ng/mL. Milk samples spiked with phenanthrene (5.0μg/mL) were assayed via this method and recoveries ranging from97.11%to101.9%were obtained showing that our strategy is potentially applicable for the preconcentration, recovering, and monitoring of trace PAHs in complex mixtures.