Preparation And Modification Of Na YF₄:YB,Er UCNPs And Its Fluorescent Responses To Bisphenol A

Lanthanide-doped upconverting luminescent nanoparticles(UCNPs) are promising materials for optical imaging-guided drug delivery and therapy due to their unique optical and chemical properties. When UCNPs are excited by a near infrared(NIR) source(e.g., 980 nm), they emit higher-energy photons at a range from ultra-violet(UV) to NIR. Such a unique and fascinating photoluminescence property offering UCNPs various distinctive characteristics, such as narrow emission bandwidths, minimal auto?uorescence back-ground, non-blinking, less light scattering, high resistance to photo-bleaching, large anti-Stokes shifts, deeper tissue penetration and so on.In this paper, we prepared Na YF4:Yb3+,Er3+ nanoparticles of different size and morphology by using hydrothermal method. In order to enhance the application of the products, different surface active agent were used to coat on the surface of nanoparticles, such as: OA, CTAB, PAA, the coating of these agent greatly enhanced the water solubility of the prepared products. Besides, the reaction conditions, such as reaction time, temperature and amount of Na F were studied to find out how the influence the synthesis of UCNPs. The fluorescent properties and morphology of the products were characterized by the Fluorescent spectrophotometer and the transmission electron microscopy(TEM). The research on the synthesis of UCNPs have laid a solid foundation for its further application in the field of biosensors.A series of surface modifications were conducted to extend the application of the UCNPs. First, the silanization procedure was adopted in order to facilitate the further modification of other ligands. The modification of silica were convinced by TEM. Afterwards, the surface was further functioned by amino groups, which can coupled with other moieties. These modification procedures extended the application of the UCNPs. The products were characterized by FT-IR to verify the functionalization of amino.We found that the sensitivity of the response signal wa s improved by the doping of Au nanoparticles in the sensor. Thus we also did some research on the synthesis of Au nanoparticles. The preparation of the Au nanoparticles were conducted in water and organic phase, respectively. The morphology were characterized by the corresponding measures.Due to the fluorescent response from UCNPs to BPA, That is the fluorescence intensity of UCNPs is decreased with the increase of BPA. By combination of silica molecularly imprinted technology with APTES as monomer and TEOS as cross-linker, we have prepared a molecular imprinted polymer(MIP) for the detection of bisphenol A(BPA). The MIP showed a good response to the BPA in the concentration of 50 ng/ml-500 ng/ml.