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A novel nanocarrier of magnetic Fe(3)O(4)-graphene nanocomposites (MGNs) was proposed as an effective drug delivery system for cancer treatment. The nanocarrier was synthesized by covalently attaching modified Fe(3)O(4) nanoparticles onto water-soluble graphene sheets via the formation of an amide bond with the aid of 1-ethyl-3-(3-dimethyaminopropyl) carbodiimide. The obtained MGNs exhibited excellent dispersibility and stability in aqueous solution and they also exhibited superparamagnetic properties with a saturation magnetization of 23.096 emu g(-1). An efficient loading of 5-fluorouracil (5-FU) on MGNs as high as 0.35 mg mg(-1) was obtained. Furthermore, the in vitro drug release of 5-FU was examined in pH 6.9 and pH 4.0 buffers at 37 °C, and showed strong pH dependence. Transmission electron microscope observations revealed that MGNs can be internalized efficiently by HepG2 cells. More importantly, the cytotoxicity evaluation shows that the resulting MGNs exhibit excellent biocompatibility. The as-prepared nanocarrier system combined the advantages of the superparamagnetic iron oxide nanoparticles and water-soluble graphene sheets, which will find many potential applications in biomedicine and biomaterials.

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The delicate influence of minute structural difference, such as regiochemistry, on self-assembly and phase behaviors has been commonly observed in small molecules but rarely in synthetic polymers. Herein, we report the precision synthesis of a series of double-chain giant surfactant regioisomers and their distinct phase structures and phase behaviors. These giant surfactants possess a hydroxyl-functionalized cubic T8 polyhedral oligomeric silsesquioxane head and two polystyrene tails tethered at para-, meta-, and ortho-configurations and were prepared following the sequential “click” method. As revealed by temperature-dependent small-angle X-ray scattering and bright-field transmission electron microscopy, their order–disorder transition temperatures decrease in the order of ortho-, meta-, and para-isomers, while order–order transitions were observed in the meta-isomer from lamellae to double gyroids and in the ortho-isomer from double gyroids to hexagonal cylinders upon increasing temperature. The mechanisms are elucidated by the influence of the tethering positions on the different free energy contributions, i.e., the interfacial energy, the head-to-head interaction, and the entropic energy of the tails. The distinct assembly behaviors of the three regioisomers are unusual in macromolecules yet resemble small molecules. It opens an avenue to fine-tune the macromolecular assembly at the level of molecular precision.