RSC Advances

Yousefi, Ali; Javadian, Soheila; Dalir, Nima; Kakemam, Jamal; Akbari, Jafar

doi: 10.1039/c4ra10995cpmid: N/A

The inhibition performance of six cationic ionic liquids (ILs); 1-ethyl-3-methylimidazolium chloride (EMIm Cl), 1-butyl-3-methylimidazolium chloride (BMIm Cl), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIm PF6), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIm BF4), 1-butyl-3-methylimidazolium bromide (BMIm Br), and 1-hexyl-3-methylimidazolium chloride (HMIm Cl) and their mixtures with an anionic surfactant, sodium dodecyl sulfate (SDS), was investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), atomic force microscopy (AFM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR) and quantum chemical calculations. Using these ILs, which differ in counter ion or chain length, allowed investigation of counter ion types and tail length effects on inhibition efficiency. The results show that formation of a three-dimensional hydrogen bond network between imidazolium rings and their counter ions can effect the corrosion behavior on mild steel. Among the studied ILs, HMIm Cl exhibited the best inhibition efficiency. Moreover, the theoretical quantitative structure activity relationship (QSAR) methods were used to predict the inhibition efficiency. Solutions of ILs/SDS mixtures showed good inhibition properties compared to solutions of individual surfactant and ILs, due to strong adsorption on the metal surface and formation of a protective film. In ILs/SDS mixed systems, the attractive electrostatic interaction between them is an advantage for vesicle or wormlike micelle formation, leading to an increase in inhibition efficiency. It is clear from the DLS results that the average aggregate size appears to increase with increasing chain length. The interaction between ILs/SDS on the metal surface (in the solid–liquid interface) was analyzed on the basis of regular solution theory. The results demonstrated that attractive interactions between ILs and SDS were strong in the solid–liquid interface. The flow effect was studied using a rotating disc electrode (RDE). The results confirmed that aggregates formed of ILs/SDS interaction are not stable and separated from the surface under flow condition. Metal surface characterization was performed using AFM and FT-IR. Potentiodynamic polarization investigations indicated that the studied inhibitors were mixed type inhibitors. Adsorption of the inhibitors on the mild steel surface obeyed the Langmuir adsorption isotherm. Furthermore, adsorption (ΔG0ads) free energy in mixtures decreased compared to single ones.

Dong, Fan; Feng, Xin; Zhang, Yuxin; Gao, Chunfeng; Wu, Zhongbiao

doi: 10.1039/c4ra15798bpmid: N/A

Bismuth-based nanostructured materials have attracted great interest in a wide range of applications. In the present work, 3D (BiO)2CO3 hierarchical microspheres self-assembled by nanosheets were synthesized by a simple hydrothermal method. By using a facile anion-exchange strategy, (BiO)2CO3/amorphous Bi2S3 heterostructures were constructed through the controlled chemical reaction between (BiO)2CO3 microspheres and Na2S in an aqueous solution. The as-prepared samples were systematically characterized by XRD, SEM-EDX, TEM, FT-IR, XPS, UV-vis DRS and PL techniques. The heterostructured samples were applied for photocatalytic removal of ppb-level NO in air under visible light irradiation. The pure (BiO)2CO3 hierarchical microspheres exhibited decent visible light photocatalytic activity due to the surface reflecting and scattering effect. Amorphous Bi2S3 showed no photocatalytic activity due to narrow band gap. By hybridization of (BiO)2CO3 microspheres with amorphous Bi2S3 on the surface, 3D hierarchical (BiO)2CO3/amorphous Bi2S3 heterostructures were constructed, which demonstrated increased solar light absorption and highly enhanced visible photocatalytic activity and stability. The enhanced performance can be directly ascribed to the increased visible light utilization, promoted charge separation arising from the well-matched band structure and accelerated reactants transfer resulting from special 3D hierarchical structure. The present work opens a new avenue for modification of wide-band gap semiconductor with amorphous components, which could reduce the further thermal treatment and production cost.

Barman, Jharna

doi: 10.1039/c4ra12407cpmid: N/A

Aptamers are short single stranded nucleic acid molecules, isolated from a pool of nucleic acid molecules by the method called SELEX (Systematic Evolution of Ligands by EXponential Enrichment) that can bind to the target with high affinity and specificity. A modified SELEX method where the targets are living whole cells is referred as cell-SELEX, and is of great interest because it opens up a simple and effective method for disease diagnostics and therapeutics. The cell-SELEX based approach and recent developments of the technique for identifying aptamers as well as their application in cancer diagnostics and therapeutics are summarized here.

Liu, Yongjun; Li, Tingting; Chen, Weiwei; Guo, Yuanyuan; Liu, Lixiang; Guo, Hong

doi: 10.1039/c4ra13898hpmid: N/A

A facile generic strategy is employed to prepare hierarchical hollow TiO2@CeO2 nanocubes via fast simultaneously coordinating etching and precipitation reactions. The intrinsic hollow cubic nature, as well as the heterojunction effect of the unique nanostructures, contributes greatly to its enhanced performance for photocatalytic detoxification of cyanide.

Guo, Dongman; Lu, Yun; Zhao, Yibo; Zhang, Xuetong

doi: 10.1039/c4ra16024jpmid: N/A

Aerogel materials possess a wide variety of exceptional properties, including a quite low density, high specific surface area, high porosity, etc. Considering that both graphene aerogels and ZrO2 aerogels have advantages and disadvantages respectively, graphene/ZrO2 composite aerogels are prepared, by a facile step, to enable them to have low thermal conductivity and to enhance the electronic interaction between the ZrO2 nanoparticles and graphene sheets. The chemical composition and crystalline structure of the resulting graphene/ZrO2 composite aerogels, as well as the strong interaction between the graphene sheets and the ZrO2 nanoparticles, have been disclosed by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and X-ray powder diffraction (XRD). The morphology and hierarchically porous attributes of the resulting graphene/ZrO2 composite aerogels have been investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption–desorption tests. The mechanical properties, electrical conductivity, electrochemical properties and thermal conductivity (as well as thermal stability) of the resulting graphene/ZrO2 composite aerogels have also been revealed in this study.

Das, Pranab J.; Das, Jupitara

doi: 10.1039/c4ra12298dpmid: N/A

Ionic liquids (IL) prepared from dialkylamines and concentrated sulphuric acid were used in an operationally simple, cost effective, efficient and environmentally benign synthesis of xanthenes and benzoxanthenes. Three ILs were screened for their efficiency as promoter of the synthesis. Results indicate di-n-propylammoniumhydrogensulphate to be the most efficient IL. Product recovery is simple and the IL could be recovered for reuse.

Bouchet, Lydia M.; Peñéñory, Alicia B.; Robert, Marc; Argüello, Juan E.

doi: 10.1039/c4ra16154hpmid: N/A

The mechanistic aspects of the electrochemical reduction of phenacylthio- and selenocyanates have been studied. With phenacylthiocyanates (1), a change in the reductive cleavage mechanism is observed as a function of the substituent on the phenyl ring. While a stepwise mechanism involving the intermediacy of a radical anion is followed for substrates bearing a strong electron withdrawing group, such as cyano and nitro substituent (1d, 1e), and a concerted mechanism is favoured for compounds bearing an electron-donating or no substituent on the phenyl ring (1a–c). A regioselective bond cleavage leads to the fragmentation of the CH2–S bond with all compounds 1a–e, further yielding the corresponding 1,4-diketone (3) as products. Contrastingly, with phenacylselenocyanates (2), two different reductive cleavages occur involving the breaking of both the CH2–Se and Se–CN bonds. Several products are obtained, all coming from nucleophilic attack at the α (phenacyl) carbon or the selenium atom.

Liu, Lu; Shi, Yongqian; Yu, Bin; Tai, Qilong; Wang, Bibo; Feng, Xiaming; Liu, Hui; Wen, Panyue; Yuan, Bihe; Hu, Yuan

doi: 10.1039/c4ra12897dpmid: N/A

Graphitic carbon nitride (g-C3N4)/montmorillonite (Na-MMT) nanohybrids were successfully fabricated by a facile mixing strategy and then introduced into a sodium alginate host to prepare nanocomposites with different loading levels using a casting technique. The introduction of 4.0 wt% nanohybrids led to the maximal improvement by ca. 149 °C in thermal stability. The improvement of the thermal stability was due to the reason that the mutual intercalation weakened the interlayered interaction of g-C3N4 nanosheets or Na-MMT sheets and enhanced the physical barrier effect that retarded the permeation of heat and the escape of volatile products. This work may provide an approach for exploiting g-C3N4 based materials.

Quan-Jun, Yang; Jun, Bian; Li-Li, Wan; Yong-Long, Han; Bin, Li; Qi, Yu; Yan, Li; Cheng, Guo; Gen-Jin, Yang

doi: 10.1039/c4ra14128hpmid: N/A

Background: cachexia is common in cancer patients, with profound metabolic abnormalities in response to malignant growth of cancer and progressive catabolism of host. Previous studies showed pharmacodynamics efficacy of curcumin in the prevention and treatment of cancer cachexia. However, the metabolic regulation effect is still unknown. Methods: we employed a proton NMR-metabonomics method to investigate the metabolic features of cancer cachexia and the contribution of curcumin to serum metabolites in a mouse model bearing CT26 tumor. Results: curcumin treatment (200 mg per kg per day) resulted in 13.9% less body weight loss and conserved mass of epididymal fat, muscle gastrocnemius and muscle tibialis anterior 91.4%, 11.5%, and 13.7% respectively in cancer cachexia mice. Proton NMR-based metabolomics revealed the altered metabolic profile and found 25 sensitive metabolites associated with cancer cachexia. Moreover, curcumin treatment resulted in metabolic reprogramming including decrease of phenylalanine, alanine, carnosine, carnitine, taurine, S-sulfocysteine, citrate, malate, glucose, and increase of citrulline, valine, isoleucine, methionine, glycine, acetoacetate and lactate. The pathway analysis showed that the main metabolic regulation of curcumin involved the metabolism of valine, leucine and phenylanaline, and synthesis and degradation of ketone bodies. Conclusions: these altered metabolic pathways imply a highly specific metabolism regulation of curcumin and raise the possibility for its therapeutic effect on alleviating cachexia hypermetabolism.

Zhang, Liuyang; Wang, Xianqiao

doi: 10.1039/c4ra16944apmid: N/A

The health risk associated with high cholesterol levels in the human body has motivated intensive efforts to lower them by using specialized drugs. However, little research has been performed utilizing nanomaterials to remove extra cholesterol from living tissues. Graphyne, a 2D lattice of sp2- and sp1-hybridized carbons similar to graphene, possesses great potential for cholesterol extraction from cell membranes due to its distinct porous structure and outstanding surface adhesion. Here we employ molecular dynamics simulations to explore pathways for cholesterol removal from protein clusters by using graphyne as a promising vehicle. We first demonstrate the adhesive strength between a single cholesterol molecule and different types of pristine graphyne, which provides the foundation for the graphyne–cholesterol interaction and the dynamic cholesterol removal process within a protein cluster. The sp1-hybridized carbons in graphynes are potentially more reactive than the sp2-hybridized carbons in graphene, which bestows graphynes with a remarkable affinity for cholesterol molecules. Simulation results show that graphynes with more sp1-hybridized carbon linkers can extract more cholesterol molecules than those with fewer linkers. The movement rate of graphyne across the protein cluster also plays an important role in determining the amount of removed cholesterol molecules from the system of interest. The hybrid structure of graphyne with cholesterol molecules in its partial pores also possesses outstanding adhesive strength, showing better cholesterol removal performance than pristine graphyne. These findings open up a promising avenue to exploit the capability of graphyne for biomedical applications.