Synthesis and characterization of magnetic polymeric nanocomposites for pH-sensitive controlled release of methotrexate.

As one of the well-known anticancer drugs, methotrexate (MTX) has been limited in clinical application due to its side effects on normal tissues. This study focused on the one-step hydrothermal synthesis and in vitro evaluation of Fe3O4/RGO-PEI as MTX carriers for targeted anticancer therapy. In which, the Fe3O4 provided magnetic response properties; RGO acted as a stage for Fe3O4 loading and improved the dispersion of Fe3O4; polyethylenimine (PEI) was used as a surface modifier and a storehouse for MTX. The prepared Fe3O4/RGO-PEI nanocomposites exhibited a suitable size, good stability and magnetic responsibility. And the MTX loading content and loading efficiency were calculated to be 26.6% and 90.5%, respectively. What's more, due to the diffusion and dissolution of PEI, the Fe3O4/RGO-PEI-MTX exhibited excellent pH-sensitivity, the values of MTX release rate (%) within 48 h at pH 5.8 and 4.0 were 64.3% and 87.4%, respectively. Furthermore, MTT assays in cancer cells (HepG2) and normal cells (HUVEC) demonstrated that Fe3O4/RGO-PEI-MTX exhibited high anticancer activity while low toxicity to normal cells, and also the Fe3O4/RGO-PEI composites were practically non-toxic. Thus, our results revealed that Fe3O4/RGO-PEI-MTX would be a competitive candidate for targeted delivery and controlled release of MTX.

Ionothermal synthesis of octahedral lanthanoid coordination networks exhibiting slow magnetization relaxation and efficient photoluminescence.

An ionothermal reaction of lanthanoid salts with tetraethyl-p-xylenediphosphonate (tepxdp) in ionic liquids, such as choline chloride and malonic acid, resulted in the formation of three novel lanthanoid-organic coordination networks with the formula [Ln(H2pxdp)1.5]n {Ln = Tb (1), Dy (2) and Ho(3) and H4pxdp = p-xylenediphosphonic acid}. The structures, photoluminescence and magnetic properties of the three compounds were investigated in detail. Single crystal X-ray diffraction analysis revealed that the three compounds are isostructural and the Ln3+ ions show an unusual six-coordinate environment with the {LnO6} octahedron. In these compounds, each {PO3C} tetrahedron is corner-shared with two {LnO6} octahedra and each {LnO6} octahedron is corner-shared with six {PO3C} tetrahedra, thus forming an inorganic layer in the crystallographic ab plane. The inorganic layers are further connected by a phenyl group, leading to a three-dimensional framework. Compound 1 exhibits the strong and characteristic emission of TbIII with an impressive quantum yield of 46.2%. Detailed magnetic analysis demonstrated that compound 2 displays a slow magnetic relaxation of magnetization with multiple relaxation mechanisms. The anisotropic energy barrier and the pre-exponential factor τ0 are 51.2 K and 3.9 × 10-7 s, respectively, in the presence of a direct-current field of 500 Oe. This work demonstrates a successful strategy to isolate octahedrally coordinated lanthanoid complexes through ionothermal synthesis to exhibit the single-ion-magnet-like behaviour and photoluminescence properties.

pH-sensitive magnetic drug delivery system via layer-by-layer self-assembly of CS/PEG and its controlled release of DOX.

Cancer is one of the biggest killers threat to human life and health and is still difficult to treat mainly due to the lack of targeted drug delivery stages and limitations associated with delivering drugs to targeted cancer tissues. The goal of this work was to develop a magnetic, pH-sensitive formulation for targeted delivery of chemotherapeutic agents to cancer cells. Then the functional drug delivery system (Fe3O4@CS/PEG-DOX) was synthesized by the layer-by-layer (LbL) self-assembly technique. And the drug loading content is calculated to be 19.1%. In addition, the Fe3O4@CS/PEG-DOX exhibited excellent pH-sensitivity, 73.1% DOX was released within 48 h at pH 4.0. Furthermore, all the release behaviors fit the Higuchi model very well and the dissolution of CS/PEG layers played a key role on DOX release from Fe3O4@CS/PEG-DOX. The results of toxicity analysis in human liver hepatocellular carcinoma cells (HepG2) revealed that Fe3O4@CS/PEG-DOX exhibited high anti-tumor activity, while the Fe3O4@CS/PEG nanocomposites were practically non-toxic. Therefore, all the results demonstrated that the Fe3O4@CS/PEG-DOX could have an important impact on the development of targeted intracellular delivery nanodevices for cancer therapy.

Influence of Molecular Weight on Structure and Catalytic Characteristics of Ordered Mesoporous Carbon Derived from Lignin.

Bio-renewable lignin has been used as a carbon source for the preparation of porous carbon materials. Nevertheless, up to now, there are few studies about the influence of molecular weight of lignin on the structure and morphology of the ordered mesoporous carbon. Here, we synthesized the ordered mesoporous carbon derived from different molecular weights of lignin and Pluronic F127. Fortunately, we found that molecular weight is an important factor for obtaining highly ordered channels, high specific surface area, and ordered mesoporous carbon. More importantly, the narrow well-defined mesoporous channel could exert a spatial restriction effect to some extent, which can serve as nanoreactors for efficient reactions and enhance catalytic performance. The highly ordered mesoporous carbon from lignin is a good candidate for Fischer-Tropsch synthesis catalyst supports.