Studies On Designing, Assembly, And Application Of The Smart Nanoparticles Doped With Rare-earth Complexes

Rare-earth complexes often posses many typical optical and magnetic properties based on the special properties of rare-earth ions, for example, the broad and independent emission peaks from the coordination environment, which almost cover the whole light region, changing from short UV light to the visible light and NIR light. Meanwhile, the f-f forbidden transition of rare-earth ions enables the luminescent lifetime of rare-earth complexes to be very long. Specially, the visible light emissions of rare-earth complexes are investigated mostly, which applicated in light industry to form light and luminescent materials, immunoassay and optical imaging in vivo. At the same time, Gd(III) based complex has used in clinic as a T1-weighted MRI contrast agent. Considering the above advantages, it is confirmed that rare-earth complexes have an important research value in various fields. As well known, the excitation wavelengthes of rare-earth complexes are almost in UV region, and the photo-thermal stability of them is not very ideal, which both limited the application in reality. Compared to the single complex, the nanoparticles doped with rare-earth complexes can solve the above problems, so in our work, we mainly focused on the assembly of the doped luminescence materials. In order to make a strong interaction between guest complexes and host hybrid, we chose rare-earth doped hybrid nanoparticles and different organic ligands for in situ coordination. All the results confirmed that there are a series of energy transfer channels existed in the assembly. The improved photo-thermal stability and enhanced luminescent intensity make them a potential candidate in phosphors and theranostics application.The dissertation is mainly divided into following four chapters:Chapter 1: A brief introduction of the concept and application of rare-earth complexes doped materials and theranostics.Chapter 2: Novel multi-color photoluminescence emission phosphors developed by layered gadolinium hydroxide via in situ intercalation with positively charged rare-earth complexes.The design of multi-color phosphors has aroused great interest for practical optical applications. Herein, forthe first time, the stable positively charged Eu(III) and Tb(III) complexes EuL1 and TbL1(L1=2,2′-(4-(2-ethoxyethoxy)pyridine-2,6-diyl)bis(4,5-dihydrooxazole)) have been successfully intercalated in situ intothe gallery of layered gadolinium hydroxide(LGdH) utilizing chelation of picolinic acid(pa) anions via ligand exchange reaction. In particular, the resulting hybrid phosphors(LGdH-pa-Eu1-xTbxL) exhibit multi-color emissions by simply fine-tuning the molar ratio of Eu(III)/Tb(III), which show red and green primary colors, as well as intermediate colors excited at 310 nm. The luminescence spectra, decay time, and low-temperature phosphorescence spectra analysis indicate that other than the intramolecular energy transfer(ET) process from ligand to RE(III) and intermolecular ET process from Tb(III) to Eu(III), the expected and interesting interaction between host(LGdH) and guest pa anions was also observed, which dramatically enhanced the absorption cross section of pa anions. Finally, a blue emission component 4,40-distyrylbiphenyl sodium sulfonate(Tinopal CBS) was further introduced into the hybrid material LGdH-pa-Eu0.2Tb0.8L, to provide white light emission under the 330 nm excitation. In order to determine the potential of these hybrid phosphors in various applications, transparent and multi-color emission composite film devices have been fabricated with poly(methyl methacrylate)(PMMA) using the solvent-casting method. Meanwhile, the observed energy transfer channels settled a good foundation for the fast development of our second work.Chapter 3: Two-photon sensitized hollow Gd2O3:Eu3+nanocomposites for real-time dual-mode imagingand monitoring of anticancer drug release.Herein, we describe the design, assembly protocol, and full characterization of novel multifunctional nanocomposites based on the modified hollow Gd2O3:Eu3+ nanoparticles(NPs), as well as their application for the efficient dual-mode imaging, real-time monitoring of drug release by PL and MRI signals, and targeted response cancer therapy. The drug-free nanospheres Gd2O3:Eu3+@P(NIPAm-co-MAA)@THA@cRGD(designated as TPNPs@cRGD) were developed via a stepwise modification of the hollow Gd2O3:Eu3+NPs with poly[(N-isopropylacrylamide)-co-(methacrylic acid)] {P(NIPAmco-MAA)}, 4,4,4-trifluoro-1-(9-pentylcarbazole-3-yl)-1,3-butanedioneanion(THA), and amine-functionalized cRGD(cyclic(Arg-Gly-Asp-D-Phe-Lys)). Based on coordination effect of drug loading, PL signals of Eu3+ and MRI signals of Gd3+ can be stabilized and enhanced, respectively, which then display excellent linear decreases on drug release. Therefore, this study constructed a unique platform for potential drug delivery, targeting drug release, multimodal imaging and monitoring of drug release simultaneously. Meanwhile, the obtained results also laid the foundation of our third work.Chapter 4: Dually NIR/pH-responsive rare-earth oxide nanocomposites for multimodal imaging and enhanced chemo-photothermal-photodynamic tumor therapy.The combination of multiple therapy strategy has attracted more attention because their promising antitumor effect. In this study, the doxorubicin(DOX) and indocyanine green(ICG) loaded Gd2O3:Eu3+@P(NIPAm-co-MAA)@THA@cRGD nanocomposites(DOX-ICG-TPNPs@cRGD) have been prepared for multi-mode imaging diagnosis and therapy. As expected, the designed nanocomposite displayed a versatile platform including simultaneous targeting with cRGD, multi-mode imaging with two-photon luminescence(TPL)/magnetic resonance imaging(MRI)/computed tomography(CT) imaging/ photothermal imaging(PTI), stimuli-responsive coordinated drug delivery, and combined therapy with chemotherapy/photo-thermal/photodynamic therapy(chemo/PTT/PDT). More importantly, both PTT and PDT effects of ICG were enhancedin the nanocomposites compared to the free ICG because of the effective light protection of two-photon sensitized Eu3+ complexes. The integrated strategy significantly had an excellent synergistic inhibition of tumor with a mild laser irradiation. Our study highlights the interaction influence between every component in the assembly, and demonstrates the importance of systematic design of nanoplatform for greatly enhanced antitumor efficacy.