RSC Advances

Pourjavadi, Ali; Hosseini, Seyed Hassan; Matloubi Moghaddam, Firouz; Ayati, Seyed Ebrahim

doi: 10.1039/c5ra00127gpmid: N/A

A novel heterogeneous copper catalyst was synthesized in which poly(1-vinyl imidazole-co-ionic liquid) was used as a solid heterogeneous support. The catalyst was readily synthesized in a large scale amount. The catalyst has a high loading level of copper ions and can be used in low weight percentages. The resulting catalyst was highly active in the preparation of triazoles by the Huisgen 1,3-dipolar cycloaddition method. In some cases the catalytic turnover number and frequency reached 70 002 and 3889 h−1, respectively. The catalyst was recycled many times without significant loss of activity.

Dong, Guangzhi; Fan, Huiqing; Tian, Hailin; Fang, Jiawen; Li, Qiang

doi: 10.1039/c5ra01869bpmid: N/A

Pure and Ba-substituted bismuth ferrite (BiFeO3, BFO) powders were successfully synthesized via a sol–gel method. The effects of the Ba-substitution on the morphology, gas-sensing and electrical properties of BFO were studied. The gas-sensing tests show that the sensor based on Bi0.9Ba0.1FeO2.95 (BBFO10) has high sensitivity, quick response, effective selectivity and excellent long-time stability. The conduction mechanism and gas-sensing mechanism of a BBFO10 sample were investigated by the impedance spectroscopy and it was found that the conduction is dominated by p-type hole conduction. The conductivity of the sensor is dependent on the oxygen partial pressures and the type of gas atmosphere. The enhanced gas-sensing performances of the BBFO10 sensor are attributed to the higher oxygen vacancy concentration which was induced by the substitution of Bi3+ ion by an aliovalent Ba2+ ion at the A-site of the perovskite structure.

Chen, Lei; Gao, Yixun; Fu, Yanyan; Zhu, Defeng; He, Qingguo; Cao, Huimin; Cheng, Jiangong

doi: 10.1039/c5ra02472bpmid: N/A

The vapor of peroxide explosives (PEs) is difficult to detect using fluorescent probes because PEs are not typical quenching agents, not having nitro groups or aromatic units that can easily interact with electron-rich probes. Three borate ester endcapped pyrenyl–fluorene copolymers were reported for the detection of PEs, including a hyperbranched polymer (S1) and two linear polymers with borate esters on fluorenyl (S2) or pyrenyl (S3) units. It was found that the hyperbranched polymer S1 has greater steric hindrance, more external borate ester groups, higher HOMO level and higher fluorescence quantum yield, which give it higher sensitivity to H2O2 vapor than S2 and S3. To further amplify the sensing performance toward H2O2 vapor, a polymer/ZnO nanorod array composite was used, exploiting the catalytic ability and high area to volume ratio of the ZnO nanorod array. The fluorescence of the S1 film is quenched by ∼60% and ∼30% under saturated vapor of H2O2 and TATP, respectively, for 300 s at room temperature, and the detection limit for H2O2 is estimated to be 1.6 ppb. These results reveal that the S1/ZnO nanorod array composite is very promising for the preparation of a highly sensitive fluorescence device for detecting the vapor of peroxide explosives.

Wang, Tian-Ming; Ding, Li-Qing; Jin, Hua-Jia; Shi, Rong; Wu, Jia-Sheng; Zhu, Li; Jia, Yi-Qun; Ma, Yue-Ming

doi: 10.1039/c5ra00776cpmid: N/A

Longhu Rendan pills (LRPs), a traditional Chinese over-the-counter medicine, have been used for the prevention and treatment of heatstroke and motion sickness. A sensitive, specific, and accurate headspace-solid-phase dynamic extraction method coupled to gas chromatography-tandem mass spectrometry (HS-SPDE-GC-MS/MS) was developed and validated for the investigation of the pharmacokinetic properties of l-menthol, borneol, isoborneol, and the metabolite camphor in rats after oral administration of LRPs. Target compounds were extracted using an SPDE needle device coated with a polydimethylsiloxane solid phase. Detection of components was achieved by GC-MS/MS in multiple reaction monitoring mode. This method was successfully applied in the evaluation of the pharmacokinetics of components and a metabolite of LRPs after a single intragastric administration of a 0.92 g kg−1 dose to rats. Pharmacokinetic parameters were calculated from the plasma concentration–time data. Cmax values of l-menthol, borneol, isoborneol, and camphor in rat plasma were determined to be 876 ± 341, 268 ± 149, 158 ± 91, and 126 ± 56 ng mL−1, respectively, and the AUC0–t values were measured as 876 ± 259, 408 ± 121, 140 ± 50, and 401 ± 35 ng h mL−1, respectively. These results provide useful information on the effective components of LRPs.

Li, Xue-Wu; Zhang, Qiao-Xin; Guo, Zheng; Yu, Jin-Gui; Tang, Ming-Kai; Huang, Xing-Jiu

doi: 10.1039/c5ra00324epmid: N/A

Superhydrophobic 5052 aluminum alloy substrates with excellent corrosion resistance have been fabricated by a simple and low-cost method of acid treatment and modification of fluoroalkyl-silane combined with surface passivation. Via an etching process with hydrochloric acid, hierarchical convex–concave micro/nano-structures have been formed on 5052 aluminum alloy surfaces. Then they were covered with a flocculent layer after passivation with potassium permanganate. The wettability and corrosion resistance of the as-prepared substrates have been systematically investigated. The results indicate that aluminum alloy substrates with an etching time of 5 min and passivation time of 180 min exhibit good superhydrophobicity with a water contact angle of 153 ± 0.7°. In addition, corrosion resistance was also explored by potentiodynamic polarization curves and electrochemical impedance spectroscopy. Clearly, the corrosion resistance of the as-prepared aluminum alloy substrates has been greatly enhanced, which will be positive to extend further the applications of Al alloys in engineering fields, such as shipbuilding and oceanographic engineering.

Sun, Zhengbo; Zhang, Wenlu; Zhang, Pengfei; Gao, Duyang; Gong, Ping; Yu, Xue-Feng; Wu, Yingliang; Cao, Zhijian; Li, Wenxin; Cai, Lintao

doi: 10.1039/c5ra03006dpmid: N/A

Multifunctional theranostic materials with good biocompatibility are desirable for cancer imaging and therapy. In this paper, a glioma-specific theranostic agent is prepared using Chlorotoxin fusion protein GST-CTX (gCTX) as a template to direct the synthesis of Au nanoclusters (NCs). By trapping the Au NCs in the gCTX, the prepared Au@gCTX NCs show ultrasmall size with hydrodynamic diameter of ∼2.2 nm and exhibit red-emitting fluorescence with a quantum yield of approximately 6.5%. The investigation from confocal fluorescent microscopy reveals the bright fluorescence and high specificity of the Au@gCTX NCs to label glioma cells through binding to membrane-bound matrix metalloproteinase 2 (MMP-2). Gelatin Zymography, MTT cell viability assay and flow cytometry studies further demonstrate that the Au@gCTX NCs can inhibit the enzymatic activity of MMP-2 and cancer proliferation by elevating intracellular ROS levels, and without harming normal cells. Our results suggest an efficient method for the synthesis of multifunctional theranostic agents for the treatment of cancer.

Torkpur-Biglarianzadeh, Maziar; Salami-Kalajahi, Mehdi

doi: 10.1039/c5ra01444apmid: N/A

A multi-step process was used to synthesize fluorescent folic acid (FA)-conjugated stimuli-responsive magnetic nanoparticles as anti-cancer drug nanocarriers. Sol–gel processing of tetraethyl orthosilicate and fluorescein isothiocyanate-conjugated 3-aminopropyltriethoxysilane was used to synthesize Fe3O4@SiO2–FITC followed by the distillation precipitation polymerization of 2-hydroxyethyl methacrylate and N,N′-methylenebis(acrylamide) to obtain Fe3O4@SiO2@P(HEMA) nanoparticles. Conjugating with FA and RAFT agent, Fe3O4@SiO2@P(HEMA)@P(NIPAAM-co-AA) nanoparticles were synthesized via the polymerization of N-isopropylacrylamide and acrylic acid. The core–shell structure of nanoparticles was revealed via TEM. Furthermore, the progression of each step was studied by means of FT-IR and TGA. VSM and XRD were used to show that the synthesized nanoparticles retain their superparamagnetic properties. The synthesized nanoparticles exhibited dual thermo- and pH-sensitive behaviours. These nanoparticles were used as nanocarriers of the anti-cancer drug doxorubicin via controlled release in simulated physiological and acidic conditions. In addition, the synthesized nanoparticles showed a relatively non-toxic nature to HeLa cells, whereas cell viability decreased significantly when cells were incubated with DOX-loaded nanoparticles.

Zhou, Wei; Bo, Maolin; Wang, Yan; Huang, Yongli; Li, Can; Sun, Chang Q.

doi: 10.1039/c5ra00112apmid: N/A

A combination of tight-binding theory, bond order–length–strength correlation and non-bonding-electron polarization notions, photoelectron spectrometrics, and density functional theory calculations has enabled us to examine the effect of atomic undercoordination on local bond-electron-energy relaxation pertaining to Mo(100, 110) skins and atomic clusters. This exercise has led to the following quantitative information: (i) the atomic Mo 3d5/2 energy level located at 224.862 ± 0.004 eV shifts 2.707 eV deeper upon bulk formation; (ii) the skin local bond is subject to a 9.80% contraction; and (iii) 5.952e charge transfers from the inner to the outermost skin layer. Furthermore, the E4s level shifts from 61.229 eV for Mo59 to 61.620 eV for the Mo15 cluster and the valence band undergoes a 1.057 eV upward shift. The globally positive core-level shift arises from local quantum entrapment due to bond contraction and strength gain. The densely entrapped core electrons polarize the valence electrons and hence raise the valence band energy.

Chatterjee, Debnath; Paul, Abhijit; Rajkamal, ; Yadav, Somnath

doi: 10.1039/c5ra03461bpmid: N/A

The solvent free per-O-acetylation of various reducing and non-reducing sugars has been carried out using stoichiometric amounts of acetic anhydride and copper(ii) perchlorate hexahydrate as the catalyst. The reactions with various reducing monosaccharides have also been followed by a one-pot sequential conversion to the corresponding thioglycosides in high yields.

Jain, U.; Narang, J.; Rani, K.; Burna, ; Sunny, ; Chauhan, N.

doi: 10.1039/c5ra00050epmid: N/A

Xanthine oxidase (XOD) extracted from bovine milk was immobilized covalently via N-ethyl-N′-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxy succinimide (NHS) chemistry onto cadmium oxide nanoparticles (CdO)/carboxylated multiwalled carbon nanotube (c-MWCNT) composite film electrodeposited on the surface of an Au electrode. The nanocomposite modified Au electrode was characterized by Fourier transform infrared (FTIR), cyclic voltammetry (CV), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) before and after immobilization of XOD. Under optimal operation conditions (25 °C, +0.2 V vs. Ag/AgCl, sodium phosphate buffer, pH 7.5), the following characteristics are attributed to the biosensor: linearity of response up to xanthine concentrations of 120 μM, detection limit of 0.05 μM (S/N = 3) and a response time of at most 4 s. After being used 100 times over a period of 120 days, only 50% loss of the initial activity of the biosensor was evaluated when stored at 4 °C. The fabricated biosensor was successfully employed for the determination of xanthine in fish meat.