The Fabrication Of Luminescence Guests/LDHs Composite Material And Their Photofunctionalities

Photofunctional materials with intercalation structure are a new type of layered host-guest materials based on the non-covalent interactions of photofunctional guest and 2D host structure. Such 2D host-guest materials supply an effective platform to construct new structures, to realize new functions and to achieve enhanced performances. Therefore, it has become one new development direction of supramolecular optical material. In this thesis, two kinds of photofunctional materials are selected to combine with the host material LDHs, and serval kinds of new multi-functional supermolecular optical functional materials are obtained by the use of intercalation or layer by layer assembly techniques. We also explore the preparation and performance adjusting pattern of intercalated optical functional material by regulating host-guest interactions. Scientific problems such as controllable preparation and performance enhancement of such optical functional materials are revealed, providing some theoretical exploration and application basis to supermolecular photofunctional composite materials.The major results and contents of this thesis include:1. With the layer-by-layer assembly method, the multicolor-light-emitting ultrathin films (UTFs) with two-dimensional architecture were fabricated based on CdTe QDs and MgAl-LDH nanosheets via the layer-by-layer (LBL) deposition technique. The hybrid UTFs possess periodic layered structure which was verified by X-ray diffraction. Tunable light emission in the red-green region was obtained by changing the particle size of QDs (CdTe-535 QDs and CdTe-635 QDs with green and red emision respectively), assembly cycle number and sequence. Moreover, energy transfer between CdTe-535 QDs and CdTe-635 QDs occurs based on the fluorescence resonance energy transfer (FRET), which extremely enhances the fluorescence efficiency of CdTe-635 QDs. In addition, a theoretical study based on the Forster theory and Molecular dynamics (MD) simulations demonstrates that CdTe QDs/LDH UTFs exhibit superior capability of energy transfer owing to the ordered dispersion of QDs in the 2D LDH matrix, which agrees well with the experimental results. A UTF system as a temperature sensor was fabricated based on the LBL assembly of CdTe QDs and positively charged LDH nanosheets, which shows dual-parameter detectable signals and superior temperature response sensitivity. XRD and SEM indicate that the CdTe QDs/LDH UTF has long-range order structure, with a periodic repeating distance of 12.33 nm. The UTF exhibits a linear response in luminescence intensity as well as peak position in the temperature range 23 to 80℃, with a fast response, high sensitivity, good repeatability and photostability. Highly luminescent and flexible films were fabricated via self-assembly of triple building blocks:LDH nanoplatelets, polyvinyl alcohol (PVA) and QDs (CdTe or CdSe/ZnS), which show 2D ordered structure and finely tunable fluorescence (green, yellow, orange and red). The resulting films display rather strong fluorescence and high fluorescence quantum yield (PLQY), which can be attributed to the uniform dispersion of QDs within the inorganic-organic hybrid matrix. Furthermore, we incorporated the red-emitting LDH/(PVA-CdSe/ZnS) film with the commercialized white light-emitting diodes (WLED), and obtained significantly improved color-rendering property through modifying its spectral distribution.2. A supermolecular photosensitizer with excellent anticancer behavior used in photodynamic therapy (PDT) was fabricated by incorporation of zinc phthalocyanines (ZnPc) into the gallery of LDH. The composite material possesses uniform particle size (hydrodynamic diameter:-120 nm); the host-guest and guest-guest interactions result in the high dispersion of ZnPc as monomeric state in the interlayer region of LDH matrix, with high singlet oxygen production efficiency. In vitro tests performed with HepG2 cell reveal a satisfactory PDT effectiveness of the ZnPc(1.5%)/LDH composite photosensitizer:a cellular damage as high as 85.7% was achieved with a rather low dosage of ZnPc (10μg/mL). An extraordinarily high specific efficacy was demonstrated (31.59μg-1J/cm2)-1) which is over 185.5% enhancement compared with the previously reported photosensitizers under similar test conditions. Furthermore, in vivo study of the ZnPc(1.5%)/LDH demonstrates an excellent PDT performance with an ultra-low dose (0.3 mg/kg) and a low optical fluence rate (54 J/cm2). In addition, the ZnPc/LDH photosensitizer displays high stability, good biocompatibility as well as low cytotoxicity, which would guarantee its practical applications.On the basis of the previous work, the composite nanoparticle ZnPc-DOX/LDH with PDT and chemotherapy collaborative treatment function was further prepared by intercalating ZnPc to LDH layers and loading chemotherapeutics DOX. ZnPc-DOX/LDH retains the lamellar structure of LDH and possesses high dispersion and good photostability. The host-geust interaction enables the ZnPc-DOX/LDH to possess excellent singlet oxygen generating capability. When evaluating the PDT and chemotherapy collaborative treatment functions of ZnPc-DOX/LDH with KB cells, it is found that ZnPc-DOX/LDH has outstanding collaborative treatment performance. At the concentration of 5μg/mL, ZnPc-DOX/LDH can kill 93.1% of the cells. Meanwhile, it is more effective than single PDT or chemotherapy, exhibiting better synergistic effect.Therefore, the new-typed inorganic supramolecular materials fabricated in this thesis through intercalation assembly exhibits potential prospect in photofunctional materials and tumor therapy.