Constructing Mechanical Shuttles in a Three-dimensional (3D) Porous Architecture for Selective Transport of Lithium Ions.

Lithium (Li) extraction from brines is a major barrier to the sustainable development of batteries and alloys; however, current separation technology suffers from a trade-off between ion selectivity and permeability. Herein, a crown ether mechanically interlocked 3D porous organic framework (Crown-POF) was prepared as the porous filler of thin-film nanocomposite membranes. Crown-POF with penta-coordinated (four Ocrown atoms and one Ntert-amine atom) adsorption sites enables a special recognition for Li+ ion. Moreover, the four Ntert-amine atoms on each POF branch facilitate the flipping motion of Li+ ion along the skeletal thread, while retaining the specified binding pattern. Accordingly, the crown ether interlocked POF network displays an ultrafast ion transfer rate, over 10 times that of the conventional porous materials. Notably, the nanocomposite membrane gives high speed and selectivity for Li+ ion transport as compared with other porous solid-based mixed-matrix membranes.

Mechanical Bond Approach to Introducing Self-Adaptive Active Sites in Covalent Organic Frameworks for Zinc-Catalyzed Organophosphorus Degradation.

Mechanically interlocked molecules (MIMs) with discrete molecular components linked through a mechanical bond in space can be harnessed for the operation of molecular switches and machines, which shows huge potential to imitate the dynamic response of natural enzymes. In this work, rotaxane compounds were adopted as building monomers for the synthesis of a crown-ether ring mechanically intercalated covalence organic framework (COF). This incorporation of MIMs into open architecture implemented large amplitude motions, whose wheel slid along the axle in response to external stimulation. After impregnation with Zn2+ ions, the relative locations of two zinc active sites (crown-ether coordinated Zn(II) and bipyridine coordinated Zn(II)) are endowed with great flexibility to fit the conformational transformation of an organophosphorus agent during the hydrolytic process. Notably, the resulting self-adaptive binuclear zinc center in a crown-ether-threaded COF network is endowed with a record catalytic ability, with a rate over 85.5 µM min-1 for organophosphorus degradation. The strategy of synthesis for porous artificial enzymes through the introduction of mechanically bound crown ether will enable significant breakthroughs and new synthetic concepts for the development of advanced biomimetic catalysts.

A high stable pH-temperature dual-sensitive liposome for tuning anticancer drug release.

In order to improve the targeting and availability of liposomes to cancer cells, the temperature sensitivity of 1, 2-Dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and the pH sensitivity of PASP in PASP-g-C8 are incorporated in a drug delivery system. A composite pH-temperature dual-sensitive liposomes (CPTLPs) was obtained as an efficient drug delivery system. The bionic bilayer is self-assembled by cholesterol/cationic temperature-sensitive lipids as base layer and pH-sensitive octylamine grafted poly aspartic acid (PASP-g-C8) as anchors coated outside. Cytarabine (CYT) was chosen as a model drug. SEM and DLS were used to observe the morphology characteristics of CPTLPs in different micro environment. The results demonstrated that the CPTLPs remained active in both normal (pH7.4 and 37 °C) and tumor tissues (pH 5.0 and 42 °C). As a stable colloidal system, the zeta potential of CPTSLs was -41.6 mV. In vitro drug-release experiments, the CTY encapsulated dual-sensitive liposomes, CPTSLs(+), not only have significant pH-temperature sensitivity but have more prolonged release in vitro than control groups. MTT tests results indicated that the cell apoptotic effects induced by CPTSLs(+) were nearly 30% higher than the naked drug CTY in HepG2 cells, and 20% lower apoptotic in vero cells. The CPTSLs(+) sustained a stable emulsion form, less toxic effects on normal cells, and exhibited a good pH-temperature sensitivity, thus expected to be a promising tumor targeting drug delivery.

Approach toward nanoplate poly(styrene sulfate): synthesis of nano-polymers with special morphology by using Ldhs as template.

A simple chemical method to obtain nanopolymers with special morphology is reported. The key to the success of this preparation was the use of layered double hydroxides (LDHs), a two-dimensional host material, as template. Typical procedures include in-situ polymerization of the monomers in the interlayers of the LDH template, followed by the dissolution of LDH sheets so that the formed polymers can be free and collected. The obtained results demonstrate potential of LDHs as tools for the controlled synthesis of nanopolymers with platelike morphology.