Zhiyao Sun

Biocompatible core–shell electrospun nanofibers as potential application for chemotherapy against ovary cancer

Polyvinyl alcohol/chitosan (PVA/CS) core-shell nanofibers are successfully fabricated by a simple coaxial electrospinning method, in which PVA forms the core layer and CS forms the shell layer. With the change of the feed ratio between PVA and CS, the surface morphology and the microstructures of the nanofibers are largely changed. The as-prepared core-shell fibers can be used as a carrier for doxorubicin (DOX) delivery. FT-IR analysis demonstrates that hydrogen bond between CS and PVA chains forms. The results of in vitro cytotoxicity test indicate that the core-shell fibers are completely biocompatible and the free DOX shows higher cytotoxicity than the DOX loaded nanofibers. The standing PVA/CS core-shell fibers remarkably promote the attachment, proliferation and spreading of human ovary cancer cells (SKOV3). Via observing by confocal laser scanning microscopy (CLSM), the DOX released from the fibers can be delivered into SKOV3 cell nucleus, which is significant for the future tumor therapy. And, the as-prepared fibers exhibit controlled release for loaded DOX via adjusting the feed ratio between PVA and CS, and the DOX loaded nanofibers are quite effective in prohibiting the SKOV3 ovary cells attachment and proliferation, which are potential for chemotherapy of ovary cancer.

Synthesis and optical and electrochemical memory properties of fluorene–triphenylamine alternating copolymer

A highly soluble fluorene–triphenylamine conjugated alternating copolymer (PF–TPA) was designed and synthesized under Suzuki coupling reaction conditions in this work. The structure of the copolymer was characterized by Fourier transform infrared (FT-IR) spectroscopy, and hydrogen and carbon nuclear magnetic resonance (1H-NMR, 13C-NMR). The copolymer showed excellent thermal stability, and an onset decomposition temperature up to 443 °C. The optical and electrochemical properties of PF–TPA were investigated by using ultraviolet visible (UV-vis) absorption spectroscopy, photoluminescence (PL) spectroscopy, transient photocurrent responses and cyclic voltammetry (CV). The main absorption peak of PF–TPA appeared at λmax = 382 nm in the thin film and exhibits strong photoluminescence with maximum emission peaks centered at 464 nm in chloroform. The simulation results of the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and energy band gap are −5.04, −2.22 and 2.82 eV, respectively. A non-volatile rewritable flash memory device based on the active layer of PF–TPA was fabricated with the sandwich structure ITO/PF–TPA (102 nm)/Al. The memory device exhibits good electrical bistable resistive switching behavior, with low threshold voltage (VSET ∼ −1.2 V and VRESET ∼ 3.2 V), high ON/OFF current ratio in excess of 103, high stability in retention time up to 104 s and a number of read cycles up to 300 under a read voltage of 2 V in both ON and OFF states. The conductivity mechanism of the ITO/PF–TPA/Al device is discussed. The as-fabricated device exhibited good data retention characteristics, stability and reliability.

catena-Poly[(dichloridozinc)-μ-1-{4-[(1H-imidazol-1-yl)meth-yl]benz-yl}-1H-imidazole-κ(2)N(3):N(3')].

The asymmetric unit of the title compound, [ZnCl2(C14H14N4)]n, contains a ZnII ion situated on a twofold rotation axis and one-half of a 1-{4-[(1H-imidazol-1-yl)methyl]benzyl}-1H-imidazole (L) ligand with the benzene ring situated on an inversion center. The ZnII ion is coordinated by two chloride anions and two N atoms from two L ligands in a distorted tetrahedral geometry. The L ligands bridge ZnCl2 fragments into polymeric chains parallel to [20-1].

Efficient covalent modification of graphene by diazo chemistry

Functionalized graphene is prepared by an efficient and facile approach via diazo chemistry. The modification is observed spectroscopically, and improvements in the solubility and reactivity will expedite the application of graphene.

High photoelectric PPV/PVA/Ag composite nanofibers by co-electrospinning

Abstract Poly(phenylene vinylene)/polyvinyl alcohol/Ag (PPV/PVA/Ag) composite nanofibers with excellent photoelectric properties were prepared by coaxial electrospinning using PPV/PVA as the shell and Ag nanoparticles (NPs) as the core, Ag NPs aqueous solution was prepared by the reduction method. The results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that Ag NPs are of a face-centered cubic structure, with an average diameter of 46 nm and the composite nanofibers have uniform and continuous morphology. With increasing Ag content, the diameters of the composite nanofibers decreased from 653 nm to 250 nm. The X-ray diffraction (XRD) patterns verified that in the composite nanofibers, the Ag NPs are not transformed. In the photoluminescence spectra, the PPV/PVA/Ag composite nanofibers presented red-shift compared with PPV/PVA nanofibers. Under illumination, the as-prepared PPV/PVA/Ag composite nanofibers exhibited relatively high photocurrent intensity.

catena-Poly[(dichloridozinc)-μ-4,4'-bis-[(1H-imidazol-1-yl)meth-yl]biphenyl-κ(2)N(3):N(3')].

In the title compound, [ZnCl2(C20H18N4)]n, the ZnII ion lies on a twofold rotation axis and is four-coordinated in a tetrahedral geometry defined by two Cl anions and two N atoms from two 4,4′-bis[(imidazol-1-yl)methyl]biphenyl ligands. The mid-point of the ligand is located on an inversion center, and shows a trans conformation. The ligands link the ZnII ions, forming a chain structure along [10-1].

Poly[[[diaqua-cobalt(II)]-bis-[μ(2)-1,1'-(butane-1,4-di-yl)diimidazole-κN:N]] dinitrate].

In the title compound, {[Co(C10H14N4)2(H2O)2](NO3)2}n, the CoII ion lies on an inversion center and is six-coordinated in an octahedral environment by four N atoms from four different 1,1′-butane-1,4-diyldiimidazole ligands and two O atoms from the two water molecules. The CoII atoms are bridged by ligands, generating a two-dimensional (4,4)-network. Adjacent fishnet planes are linked to the nitrate anions via O—H⋯O hydrogen bonds, forming a three-dimensional supramolecular structure.