RSC Advances

Kong, Rong-Mei; Sun, Ni-Na; Qu, Fengli; Wu, Haiyan; Wang, Hua; You, Jinmao

doi: 10.1039/c5ra18227apmid: N/A

Bleomycins (BLMs) are widely used in the clinical treatment of various cancers. Here, taking advantage of the super-quenching effect of the cationic perylene diimide derivative (PDI) on adjacent fluorophores, we reported a PDI–DNA complex based method for fluorescence “turn-on” detection of BLM, based on BLM–Fe(ii) mediated DNA strand scission. Owing to the very high quenching efficiency of aggregated PDI, the method shows low background fluorescence and high sensitivity with a detection limit of 0.2 nM. It also exhibits a good performance in complex biological samples. Moreover, this method has the advantages of no quencher labelling cost, easy preparation and rapid response, making it a promising alternative for the determination of trace amounts of BLMs in clinical samples.

Harima, Yutaka; Fukumoto, Saki; Zhang, Lu; Jiang, Xiaoqing; Yano, Jun; Inumaru, Kei; Imae, Ichiro

doi: 10.1039/c5ra17324hpmid: N/A

Composite films comprising graphene and polyaniline were prepared in one step by a facile electrochemical technique with graphene oxide (GO) and aniline monomer as raw materials, and their thermoelectric properties were investigated. Electrical conductivities of the composite films generated on the fluorine-doped tin oxide (FTO) electrode were dependent on the weight ratio of GO and aniline, and they exhibited a peak value of 30 S cm−1 at the GO/aniline ratio between 5 : 1 and 10 : 1, while Seebeck coefficients were less dependent on the weight ratio. The maximum power factor (PF) for the composite films was ca. 1 μW m−1 K−2. When the FTO electrode was replaced by the stainless steel electrode, conductivities of the composite films with the GO/aniline ratio of 8 : 1 were increased up to ca. 130 S cm−1. As a result, the PF and the dimensionless thermoelectric figure-of-merit (ZT) at room temperature reached 3.6 μW m−1 K−2 and 0.008, respectively. The ZT value is the highest among those reported so far for graphene/PANI composites. Possible reasons for the conductivity enhancement on the stainless steel electrode are also discussed on the basis of electrochemical measurements and X-ray photoelectron spectroscopy.

Hao, Wentao; Wang, Xiaomin; Ding, Songyan; Cao, Yanyan; Zhang, Hongbin; Yang, Wen

doi: 10.1039/c5ra15570cpmid: N/A

The preparation of multifunctional nacre-like hybrid films is reported in this article. The copper ions (Cu2+) were introduced into the hybrid films assembled from fluorescent hyperbranched poly(amido amine) (HPAMAM) and clay nanosheets. The “brick and mortar” structure of the hybrid films was proved by the SEM observation and SAXD detection. Due to the strong interactions among the Cu2+ ions and the HPAMAM molecules, the obtained hybrid films showed enormously improved ultimate strength. At the same time, the elongation at break of the Cu2+ modified hybrid films was more than that of the pristine one too. Furthermore, the Cu2+ ions modified hybrid films showed excellent inhibition on the bacterial growth due to the good antibacterial property of the Cu2+. Under UV irradiation, the hybrid films modified with Cu2+ could also emit strong blue fluorescence. We wish this multifunctional nacre-like hybrid film could provide a promising material for biological applications.

San Keskin, Nalan Oya; Celebioglu, Aslı; Sarioglu, Omer Faruk; Ozkan, Alper Devrim; Uyar, Tamer; Tekinay, Turgay

doi: 10.1039/c5ra15601gpmid: N/A

A contaminant resistant Lysinibacillus sp. NOSK was isolated from a soil sample and its Reactive Black 5 (RB5) and Cr(vi) removal efficiencies were investigated as a function of changes in the initial pH values, temperature, static/shaking conditions, reactive dye and Cr(vi) concentrations. In this study, an electrospun polysulfone nanofibrous web (PSU-NFW) was found to be effective in attachment of bacterial cells. Bacteria attached PSU-NFWs (bacteria/PSU-NFW) have shown highly efficient removal of RB5, as 99.7 ± 0.9% and 35.8 ± 0.4% for the pristine PSU-NFW. Moreover, the highest Cr(vi) removal efficiencies measured were 98.2 ± 0.6% for bacteria attached PSU-NFW and 32.6 ± 0.6% for the pristine PSU-NFW. Simultaneous removal of RB5 and Cr(vi) were also investigated. Reusability test results indicate that, bacteria/PSU-NFW can be reused for at least 7 cycles with 28.1 ± 0.6% and 66.7 ± 0.8% removal efficiencies for RB5 and Cr(vi), respectively.

Ren, Long-Fei; Liang, Shuang; Ngo, Huu Hao; Guo, Wenshan; Ni, Shou-Qing; Liu, Cui; Zhao, Yuan-Kun; Hira, Daisuke

doi: 10.1039/c5ra16802cpmid: N/A

To reduce operating costs and membrane fouling of conventional membrane bioreactors (cMBR), a novel MBR using a non-woven fabric membrane (nMBR) was constructed and the performance of the two MBRs was compared for anaerobic ammonium oxidation (anammox) cultivation. The results showed that the start-up period for the nMBR (44 days) was notably shorter than that for the cMBR (56 days), meanwhile the nMBR achieved a 2-times higher nitrogen removal rate (231.5 mg N per L per d) compared to the cMBR (112.3 mg N per L per d). Illumina MiSeq sequencing showed that Candidatus Kuenenia and Candidatus Jettenia were the main distinguished anammox bacteria. FISH analysis revealed that anammox bacteria predominated in both reactors, especially in the nMBR (58%) corresponding to a qPCR analysis of 1.07 × 109 copies per mL (day 120). N2O emission analysis confirmed the advantage of the nMBR in N2O reduction to reduce the influence of greenhouse gas emission while treating identical nitrogen. These results clearly demonstrated that nMBRs could be a prospective choice for anammox start-up and performance enhancement.

Lin, Hechun; Luo, Qianqian; Tong, Wen-Yi; Jiang, Chunli; Huang, Rong; Peng, Hui; Zhang, Lai-Chang; Travas-Sejdic, Jadranka; Duan, Chun-Gang

doi: 10.1039/c5ra17506bpmid: N/A

EuS and Gd2O2S nanocrystals with narrow size distribution are synthesized in high yields by the thermal decomposition of Eu(oleate)3 or Gd(oleate)3 in oleylamine using CS2 as the sulfur source. The dimensionalities of these nanocrystals can be facilely tuned by the addition of 1-dodecanethiol. The morphologies and crystal structures of EuS and Gd2O2S nanocrystals are characterized by TEM and XRD. The magnetic properties of the obtained nanocrystals are also investigated. The experimental results illustrate that CS2 is an effective sulfur source for the preparation of metal sulfide and lanthanide oxysulfide semiconductor nanocrystals.

Hu, Zhong-Ting; Lua, Shun Kuang; Yan, Xiaoli; Lim, Teik-Thye

doi: 10.1039/c5ra16409epmid: N/A

A novel bismuth ferrite, with the simultaneous formation of nanostructured clusters and controllable morphologies, was fabricated using a delicate synthesis process. By carefully controlling all processes from co-precipitation at a low temperature in water to hydrothermal treatment in methanol/water co-solvent system, nanostructured bismuth ferrite clusters with controllable morphologies composed of small bismuth ferrite crystals (∼25 nm) could be obtained. The fast crystal growth of the bismuth ferrites has been successfully hindered and a relatively pure mullite (Bi2Fe4O9) structure of the nanostructured bismuth ferrite clusters could be obtained. Their morphologies could be cube-, cuboid- and plate-like shapes with a side length of ∼400 nm, a height of ∼600 nm and a thickness of ∼80 nm. The resulting nanostructured bismuth ferrite clusters show good crystallinity, uniform elemental distributions, high chemical stability, good dispersity, reusability, and a narrow bandgap of ∼2.1 eV. They have remarkable multiplex catalytic activities in the degradation of methyl orange (MO) through visible-light photo-Fenton oxidation, dark Fenton-like reaction and solar photocatalysis. Under visible-light illumination, 99% of MO could be removed in 80 min. Without illumination, 96% of MO could be removed in 4 h. A plausible mechanism of the multiplex catalytic activities is proposed.

Reddy, P. Madhusudhana; Chang, Chi-Jung; Hsieh, Shih-Rong; Huang, Hsin-Chun; Lee, Ming-Ching

doi: 10.1039/c5ra18246hpmid: N/A

The present study explores the effect of the monomer substitution pattern of different copolymers on their volume phase transition temperature (VPTT) and surface wetting properties (SWPs) with the aid of differential scanning calorimetry (DSC), contact angle (CA), scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy (FT-IR) measurements. The present experimental results unveil that the VPTT and SWPs were greatly governed by the ability of the neighboring side chains to form intramolecular hydrogen bonds and the hydrophobic–hydrophilic balance of the polymer. The substitution of some of the acrylic acid (AA) monomers in the copolymer hydrogel P(NIPAM-co-AA) by the polyethyleneglycolmethacrylate (PEGMA) monomer resulted in the copolymer hydrogel, P(NIPAM-co-PEGMA-co-AA). The PEGMA in P(NIPAM-co-PEGMA-co-AA) can promote the intermolecular hydrogen bonds of the copolymer with the water molecules and thus hinders the formation of the intramolecular hydrogen bonds. Consequently, the VPTT of the P(NIPAM-co-PEGMA-co-AA) occurs at higher temperatures when compared to the P(NIPAM-co-AA) and P(NIPAM-co-PEGMA) systems. Further, in view of the potential applications of ionic liquids (IL) in polymer science, the effect of IL on the VPTT and SWP of the copolymers was investigated. The knowledge from this study can pave the way to engineer stimuli responsive polymers for a wide range of applications in the modern era.

Gao, Yan-Sha; Xu, Jing-Kun; Lu, Li-Min; Zhu, Xiao-Fei; Wang, Wen-Min; Yang, Tao-Tao; Zhang, Kai-Xin; Yu, Yong-Fang

doi: 10.1039/c5ra16618gpmid: N/A

In this work, a two-step method was developed for the fabrication of a graphene sensing platform doped with poly(3,4-ethylenedioxythiophene)/Au nanoparticles (AuNPs/PEDOT/GR). PEDOT nanorods grown on graphene oxide nanosheets (PEDOT/GO) were firstly synthesized by liquid–liquid interfacial polymerization, followed by the chemical reduction of HAuCl4 by NaBH4. During the reduction process, GO doped in the PEDOT was also reduced to a more conductive form of GR. The obtained AuNPs/PEDOT/GR showed excellent conductivity and large surface area. Thus, a simple and sensitive label-free immunosensor based on AuNPs/PEDOT/GR nanocomposite has been proposed to detect carcinoembryonic antigen (CEA) by measuring the change of electrochemical response before and after the immunoreaction. Under the optimized conditions, the linear range of the proposed immunosensor is estimated to be from 0.0004 to 40 ng mL−1 (R2 = 0.9969) and the detection limit is estimated to be 0.1 pg mL−1 at a signal-to-noise ratio of 3. Moreover, the immunosensor was examined for use in the determination of CEA in real human serum samples with satisfactory results.

Puchner, Claudia; Eixelsberger, Thomas; Nidetzky, Bernd; Brecker, Lothar

doi: 10.1039/c5ra18284kpmid: N/A

The human form of UDP-xylose synthase (hUXS1A) is studied with respect to its substrate and co-enzyme binding in binary and ternary complexes using saturation transfer difference (STD) NMR and in situ NMR. Obtained binding pattern results are correlated to the recently solved crystal structure of hUXS1A and docking studies of UDP-GlcUA, providing a better understanding of substrate specificity of this enzyme and may give useful information in mutant designing. In unproductive binary complexes UDP-saccharide aglycone moieties show strong STD effects with the protein. In contrast, pyranoside rings (Glc, GlcUA, Gal) indicate less interaction with the hUXS1A active site, which enables the required ring distortion of the pyranoside ring in UDP-GlcUA. In productive ternary complexes UDP-GlcUA possesses reasonable binding, while produced UDP-Xyl shows smaller STD responses and does not efficiently compete with the substrate for binding at the active site. STD NMR derived binding studies of NAD+ demonstrate tight interaction between co-factor and hUXS1A. Higher magnetization of NAD+ in the presence of enzymatic product is observed and suggests increased contact with groups on the protein. Furthermore, binding studies of substrate analogues having the same stereochemistry as the investigated UDP-saccharides and a small aglycone residue indicate a different mode of action, not guided by the anchor groups.