JOURNAL OF MATERIALS SCIENCE
·
2015
·Vol. 50
·期 14
·4914-4925
·
IF 2.371
Cheng Cui,Xia Dandan,Zhang Xiuli,Chen Li,Zhang Qiqing
The therapeutic concentration of cisplatin (CDDP) is usually associated with dose-limiting side effects. To avoid these harmful effects, a biocompatible hydrogel carrier which consisted of poly( N -isopropylacrylamide) and carboxymethyl chitosan was designed to deliver CDDP to the local environment of a solid tumor. The poly( N -isopropylacrylamide)-g-carboxymethyl chitosan hydrogels were synthesized by chemical crosslinking. Scanning electronic microscopy images showed that the hydrogels exhibited a cross-linked structure with the average pore size from 100 to 200 µm. Water contact angles and swelling studies suggested that the hydrogels had good hydrophilicity and the lower critical solution temperature lay in the vicinity of 32 °C. The MTT assays implied that the hydrogels were non-cytotoxic on NIH3T3 cells. In vitro release experiment demonstrated that the release of CDDP was controllable and sustained over a long period. Moreover, the released CDDP retained its anticancer activity on A549 cells. The hydrogels are promising carriers for sustained release of cisplatin.
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POLYMERS FOR ADVANCED TECHNOLOGIES
·
2015
·Vol. 26
·期 11
·1340-1345
·
IF 1.757
Xiangming Hu,Weimin Cheng,Wen Nie,Zhenlu Shao
In this study, a temperature-sensitive hydrogel was synthesized using N-isopropylacrylamide (NIPAm), acrylic acid, sodium alginate (SA), and starch as the raw materials, ammonium persulfate as the initiator, and N,N′-methylenebisacrylamide as the crosslinker by the free radical polymerization. The structure and properties of the hydrogel were studied. The morphology and structure were characterized by scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy was used to investigate the effects of the amount of NIPAm, SA, crosslinker, and initiator on the swelling rate (SR) of the hydrogel. The SEM images show that the surface of the hydrogel was uneven and covered with pores, sockets, and laminated intervals, favoring the swelling. The pore size increased with increasing SA amount. The volume phase transition temperature of the hydrogel decreased at a higher NIPAm amount. The SR of the hydrogel stabilized with increasing amount of SA. Increasing amount of NIPAm decreased the SR, and increasing amount crosslinker and initiator increased SR initially, followed by a decrease. Copyright © 2015 John Wiley & Sons, Ltd.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2015
·Vol. 17
·期 41
·27527-27533
·
IF 4.493
Tianxing Wu,Haimin Zhang,Xian Zhang,Yunxia Zhang,Huijun Zhao,Guozhong Wang
In this work, chitosan whiskers (CWs) were first extracted using low-cost and earth-abundant crab shells as materials by a series of chemical processes, and then assembled into chitosan whisker microspheres (CWMs) via a simple photochemical polymerization approach. Subsequently, a cementite (Fe3C) nanocrystal@N-doped graphitic carbon (Fe3C@NGC) nanocomposite was successfully fabricated by high temperature pyrolysis of CWMs adsorbed with ferric acetylacetonate (Fe(acac)3) at 900 °C. It was found that a suitable growth atmosphere generated inside CWMs during high temperature pyrolysis is critically important to form Fe3C nanocrystal cores, concurrently accompanying a structural transformation from chitosan whiskers to mesoporous graphitic carbon shells with natural nitrogen (N) doping properties, resulting in the formation of a core–shell structure Fe3C@NGC nanocomposite. The resulting samples were evaluated as electrocatalysts for oxygen reduction reaction (ORR). In comparison with sole N-doped graphitic carbon without Fe3C nanocrystals obtained by direct pyrolysis of chitosan whisker microspheres at 900 °C (CWMs-900), Fe3C@NGC showed significantly improved ORR catalytic activity. The tolerance to fuel cell molecules (e.g., methanol) and the durability of Fe3C@NGC are obviously superior to commercial Pt/C catalysts in alkaline media. The high ORR performance of Fe3C@NGC could be due to its large surface area (313.7 m2 g−1), a synergistic role of Fe3C nanocrystals, N doping in graphitic carbon creating more catalytic active sites, and a porous structure of the nanocomposite facilitating mass transfer to efficiently improve the utilization of these catalytic active sites.
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PubMed
高影响因子
Catalysis Science & Technology
·
2015
·Vol. 6
·期 6
·1913-1920
·
IF 5.426
Renfeng Nie,Hezhan Jiang,Xinhuan Lu,Dan Zhou,Qinghua Xia
N-doped active carbon (N-AC) has been synthesized via heat treatment of a mixture consisting of dicyandiamide as the nitrogen source and commercial active carbon as the precursor. This material is especially adapted for anchoring ultrafine Pd nanoparticles by a very clean strategy using H2 as the reductant. The physicochemical properties of materials were investigated by powder X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results reveal that the variation of the treatment temperature can assist the tuning of the content of N and the dispersion of Pd on xN-AC, by which Pd nanoparticles with a narrow size distribution centered at around 1.8 nm can be obtained. These robust catalysts show very high catalytic activity for the aromatic ring hydrogenation of acidic substrates, such as electron-deficient benzoic acid or electron-rich phenol, under mild conditions in aqueous media. Excellent catalytic results (9.2 times higher activity in comparison to non-doped catalyst for benzoic acid hydrogenation), high stability and easy recyclability of the catalyst were achieved. The strong interaction between the pyridinic nitrogen group and Pd species will lower the reducibility of the Pd species and result in the formation of relatively electron-deficient and ultra-small sized Pd clusters, thus leading to high hydrogenation activity.
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COLLOIDS AND SURFACES B-BIOINTERFACES
·
2015
·
IF 4.152
Shixuan Chen,Junbin Shi,Xiaolin Xu,Jianyang Ding,Wen Zhong,Lu Zhang,Malcolm Xing,Lin Zhang
The mechanical miss-match between the host and an implanted foreign body is one of the primary causes for implantation failure. To enhance the efficacy in wound repair, we developed stiffness-tunable temperature-sensitive hydrogels composed of poly(amidoamine) (PAA)-based poly( n -isopropyl acrylamide) (PNIPAM). PNIPAM-PAA hydrogels with three different stiffness fabricated by varying the concentrations of poly(amidoamine) were chosen for morphology and rheology tests. The degradation rate and cell compatibility of gels were also characterized. The PAA-PNIPAM hydrogels were then tested in a wound healing model of mice with full-thickness skin loss. We found that the stiffness of hydrogels has an impact on the wound healing process mainly by regulating the cell activities in the proliferation phase. PNIPAM-PAA hydrogels with appropriate stiffness reduce scar formation and improve wound healing by promoting myofibroblast transformation, keratinocytes proliferation, extracellular matrix synthesis and remodeling. Moreover, the stiffness of hydrogels impact on the secretion of TGF-β1 and bFGF, which play an important role in skin wound healing. These results suggest that the therapeutic effects of hydrogels in skin wound healing can by regulated by hydrogels’ stiffness.
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PubMed
高影响因子
MATERIALS RESEARCH BULLETIN
·
2015
·
IF 2.288
Weicheng Xu,Jianzhang Fang,Ximiao Zhu,Zhanqiang Fang,Chaoping Cen
A series of novel p−n junction photocatalysts BiOI/Bi 2 Sn 2 O 7 (BiOI/BSO) were successfully fabricated via a facile hydrothermal method. The phase structures, morphologies and optical properties of the as-prepared samples were studied by XRD, TEM, HRTEM, BET, XPS, UV–vis DRS and photoluminescence (PL) spectroscopy. The results showed that BiOI/BSO heteronanostructures displayed much higher photocatalytic activity than pure BSO and BiOI for the degradation of rhodamine B (RhB). The best photocatalytic activity of BiOI/BSO with almost 99.9% RhB degradation situated at molar percentage ratio of 4% after 6 h irradiation. The enhanced photocatalytic performance of BiOI/BSO could be mainly attributed to the formation of the heterojunction between p-BiOI and n-BSO, which effectively restrains the recombination of photoinduced electron–hole pairs. Moreover, the study of radical scavengers affirmed that h + and •O 2 − were the primary reactive species for the degradation of RhB.
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DRUG DELIVERY
·
2017
·
IF 6.402
Yanpu Wu,Luming Wang,Kaili Zhang,Lixiao Zhou,Xiaobing Zhang,Xuecheng Jiang,Chenggang Zhu
The local delivery of chemotherapeutic drugs to tumor sites is an effective approach for achieving therapeutic drug concentrations in solid tumors. Injectable implants with the ability to form in situ represent one of the most promising technologies for intratumoral chemotherapy. However, many issues must be resolved before these implants can be applied in clinical practice. Herein, we report a novel injectable in situ-forming implant system composed of n-butyl-2-cyanoacrylate (NBCA) and ethyl oleate, and the sol–gel phase transition is activated by anions in body fluids or blood. This newly developed injectable NBCA ethyl oleate implant (INEI) is biodegradable, biocompatible, and non-toxic. INEI solidifies in several seconds after exposure to body fluids or blood, and the implant’s in vivo degradation time can be controlled. In addition, the pore sizes formed by the polymerization of NBCA can be decreased by increasing the NBCA concentration in the implants. Therefore, the drug retention/release time can be adjusted from a few weeks to several months by changing the concentration of NBCA in the implant formulation. Anti-tumor experiments in animal models showed that the average growth inhibition rate of xenografted human breast cancer cells by the paclitaxel-loaded INEI (40% NBCA) was 80%, and they also indicated that tumors in some of the mice were completely eliminated by just a single dosage injection. For the epirubicin-loaded INEI (50% NBCA), the average growth inhibition rate of xenografted human liver cancer cells was 58%. Thus, the chemotherapeutic drug-loaded INEIs exhibited excellent therapeutic efficacy for local chemotherapy.
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PubMed
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APPLIED SURFACE SCIENCE
·
2017
·
IF 3.387
Junxia Guo,Qijian Niu,Yichun Yuan,Inamullh Maitlo,Jun Nie,Guiping Ma
One-dimensional (1D) nanomaterials have gained attention in energy conversion, storage, and catalyst due to the unique physical and chemical properties. Electrospinning is a kind of simple, versatile, and cost-effective technology to fabricate 1D functional nanofibers. Herein, electrospun polyacrylonitrile (PAN), melamine, and ferric chloride hexahydrate (FeCl 3 ·6H 2 O) composite nanofibers are used as template, and polythiophene (PT) are prepared by photopolymerization technology on the surface of electrospun nanofibers as shell part of fibers. Then, the core–shell nanofibers are pyrolyzed and converted into Fe–S/N–C nanofibers, which can be used as catalysts for ORR due to the metal and S-/N-codoped structure and unique 1D structure which provided facile pathways for efficient mass transport and charge transfer. The ORR electrocatalytic ability of Fe–S/N–C nanofibers is tested and present excellent property, especially in stability and methanol crossover. The electrocatalytic ability of sample is comparable to that of 20 wt% Pt/C benchmarks. These results offer an easy pathway for exploring metal-heteroatom-codoped carbon nanofibers applicable for ORR catalyst.
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ChemElectroChem
·
2016
·Vol. 3
·期 7
·1116-1123
·
IF 3.506
Ji Liu,Ligui Li,Wenhan Niu,Nan Wang,Dengke Zhao,Shuaibo Zeng,Shaowei Chen
Graphical A new role for the HOF : A hydrogen-bonded organic framework (HOF) comprising of melamine and trimesic acid is used as a highly porous precursor to prepare N-doped carbons by a facile, direct pyrolysis. The resulting mesoporous carbon HOF-800 has a high surface area of 1321 m 2 g −1 and efficiently catalyzes oxygen electroreduction in alkaline electrolyte. Direct carbonization methods represent a facile strategy for the synthesis of functional carbon electrocatalysts, however, the resulting carbons are mostly microporous and of low surface area, which disfavor mass transfer, and usually have low electrocatalytic activity. In this study, a hydrogen-bonded organic framework (HOF) comprising of melamine and trimesic acid is used as a highly porous precursor to prepare N-doped carbons through facile, direct pyrolysis. The high nitrogen content of melamine and the intrinsically porous nature of the HOF facilitates the formation of a mesoporous carbon with 4.8 atom % content of nitrogen dopants and a significantly high surface area of 1321 m 2 g −1 . Electrochemical measurements show that the best sample, which was pyrolyzed at 800 °C (HOF-800), exhibited efficient catalytic activity for oxygen electroreduction in 0.1 m KOH aqueous solution. This catalyst exhibits a much more positive onset potential, higher diffusion-limited current density, higher electron-transfer number in the low overpotential region, higher stability, and stronger tolerance against methanol crossover than the state-of-the-art Pt/C catalysts. The results in this study suggest the potential of intrinsically porous HOFs for the development of highly efficient nonprecious-metal electrocatalysts.
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APPLIED CATALYSIS A-GENERAL
·
2016
·
IF 4.012
Hezhan Jiang,Xiaolong Yu,Renfeng Nie,Xinhuan Lu,Dan Zhou,Qinghua Xia
Mesoporous carbon nitride (MCN) has been prepared through a simple polymerization reaction between ethylenediamine (EDA) and carbon tetrachloride (CTC) by a nano hard-templating approach. The obtained MCN possesses high surface area (166.3 m 2 /g), average pore size of 9.2 nm and high N content (up to 18.5 wt%). The negative charge and the basicity on MCN surface are originated from its rich carbon nitride heterocycles, which notably improves the surface hydrophilicity and the adsorption of acidic molecules. Furthermore, MCN can be adopted as the proper support for highly dispersed Pd NPs with well-controlled size distribution. Compared with microporous N-doped active carbon with low N-content, the MCN-supported Pd catalyst shows an enhanced activity in water phase for the selective ring hydrogenation of benzoic acid, benzamide and phenol, in which 11.3 times higher activity in comparison to undoped catalyst is achieved. Wide characterizations reveal that big pore size, selective adsorption for acid substrate and strong interaction between N and Pd may lead to the high activity of Pd/MCN.
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RSC Advances
·
2016
·Vol. 6
·期 45
·38957-38963
·
IF 3.289
Zhao Cui,Ru Cheng,Jie Liu,Youping Wu,Jianping Deng
Poly(N-acryloyl-alanine)-based hydrophobic association hydrogels were prepared through free radical polymerization of N-acryloyl-alanine (NAA) with ammonium persulfate as initiator, in which hydrophobic monomer stearyl acrylate underwent simultaneous micellar polymerization in the presence of gelatin as emulsifier. Fourier transform infrared spectra and scanning electron microscopy demonstrated the formation and microscopic structure of the resulting hydrogels. The hydrophobic association enabled the hydrogels to exhibit desirable toughness and could be molded into diverse shapes without breaking. Uniaxial tensile test and cyclic tensile test also demonstrated the high toughness of the hydrogels. The chiral monomer (NAA)-derived polymer chains rendered the hydrogels with optical activity, according to circular dichroism spectra. More fascinatingly, the hydrogels demonstrated shape memory behavior due to the hydrophobic poly(stearyl acrylate) domains. Therefore the tough chiral hydrogels are expected to find significant applications in tissue engineering and other biomedical fields.
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JOURNAL OF ASIA-PACIFIC ENTOMOLOGY
·
2017
·
IF 1.046
Yunhua Zhang,Jinyun Ji,Xiao Zhao,Ruoheng Jin,Jianhong Li,Hu Wan
A previous study demonstrated that a β- N -acetyl- d -hexosaminidase ( NlHex4 ) from the brown planthopper could serve as a new potential target for biopesticides due to its requirement for molting, and lethal phenotypes were observed via RNA interference . However, the enzymatic properties of NlHex4 remain unclear. In the present study, NlHex4 was expressed, purified and characterized. Recombinant NlHex4 was functionally expressed in baculovirus-infected insect cells and purified with a molecular weight of approximately 70 kDa. Recombinant NlHex4 had an optimal pH and temperature of 6.0 and 60 °C, respectively. Moreover, recombinant NlHex4 exhibited thermal stability at 50 °C for at least 1 h. Furthermore, the activity of recombinant NlHex4 was inhibited by the metal ions Fe 2 + and Fe 3 + and the serine protease inhibitor phenylmethanesulfonyl fluoride. These results reveal the enzymatic properties of NlHex4 and provide a basis for future investigation of the interaction between HEX and chitin oligosaccharide .
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危险品化学品经营许可证（带存储）