RSC Advances

Borker, Shaivee; Patole, Milind; Moghe, Alpana; Pokharkar, Varsha

doi: 10.1039/c6ra05202apmid: N/A

The purpose of this study was to explore the one pot green synthesis of non-cytotoxic gold nanoparticles (AuNPs) using glycyrrhizin as a reducing, stabilizing and targeting agent. The formation of glycyrrhizin (GL) capped gold nanoparticles was established by the presence of a surface plasmon resonance band at 523 nm. The as synthesized gold nanoparticles had a particle size of 17 ± 2 nm, with spherical shape and zeta potential value of −32 mV. GL-AuNPs showed excellent stability at varied pH, electrolyte conditions and cell culture media. The potential of synthesized gold nanoparticles as carrier of loaded antiviral drug lamivudine for liver targeting was explored. In vitro uptake studies by hepatocytes demonstrated a significant increase in cellular localization of GL-AuNPs as compared to citrate reduced gold nanoparticles (C-AuNPs). In vivo biodistribution study in Wistar rats proved the ability of GL-AuNPs for targeting liver. These finding can be utilized for site specific delivery of drugs for treatment of diseases affecting the liver.

Soomro, Razium Ali; Akyuz, Ozlem Polat; Akin, Husna; Ozturk, Ramazan; Ibupoto, Zafar Hussain

doi: 10.1039/c6ra05588epmid: N/A

This study demonstrates the fabrication of a highly sensitive electrochemical sensor designed for the quantification of 2,4,6-trinitrotoluene (TNT). The devised sensor system relies on the electro-catalytic reduction of TNT molecules achieved at the surface of palladium (Pd) and palladium-platinum (Pd–Pt) alloy nanostructure modified glassy carbon electrodes (GCEs). The electrode based reduction was studied in a competitive manner with Pd nanocubes (Pd NCs) in comparison to Pd hollow nanospheres (Pd HNS) and Pd–Pt alloy nanostructures (Pd–Pt NA). The experiments revealed Pd NCs to possess high catalytic capability in comparison to their other competitors where relatively greater signal sensitivity suggested the importance of shape-dependence electro-catalysis. The Pd NCs based sensor was found to be highly sensitive towards TNT molecules with detection limits up to 0.01 ppm and a working window of 0.1–7.0 ppm. Moreover, the Pd NCs based sensor demonstrated excellent selectivity in the presence of other common nitro-aromatic compounds. In addition, the excellent recoveries obtained in the real matrix environment (tap water) further promise the real-time application of the developed sensor for trace level detection of TNT.

Wang, Baorong; Lin, Min; Peng, Xinxin; Zhu, Bin; Shu, Xingtian

doi: 10.1039/c6ra06657gpmid: N/A

Hierarchical TS-1 with intracrystalline voids could be synthesized by post-modification with tetrapropyl ammonium hydroxide (TPAOH), however the process was supposed to be restrained by the charge balance effect. In order to release the constraint, NH3·H2O was introduced in the post-modification. The influences of the TPAOH/NH3·H2O modification, the TPAOH concentration and the modification time on the physiochemical properties were studied. The dissolution process and recrystallization process were observed in the combined modification, and both of them were intensified by the NH3·H2O introduced, indicating that the constraint on the OH− diffusion was released. Owing to the intensified processes, the TPAOH concentration and post-modification time could be reduced, and hierarchical TS-1 with relative high crystallinity, less defect sites and a larger secondary pore volume (about 0.18 cm3 g−1) was achieved in 4 h. However, the combined-modification exerted little influence on the chemical composition and acidity, and the microporous properties were almost the same with that of TS-1 modified with TPAOH only. The secondary porosity in the combined-modified samples were mainly intracrystalline voids, and grooves on the surface were also found. Although extra-framework titanium species were created by the post-modification, part of the titanium was still in the framework position. The catalytic activity was evaluated by phenol hydroxylation and 1-octene epoxidation, and better catalytic activity was achieved for the improved accessibility of the active sites.

Prabakaran, Kaliyappan; Ragavendran, Chinnasamy; Natarajan, Devarajan

doi: 10.1039/c6ra08593hpmid: N/A

Mosquitoes are the primary vector for transmitting endemic diseases such as yellow fever, Chikungunya, dengue and dengue hemorrhagic fever, malaria, Japanese encephalitis, and lymphatic filariasis in humans and animals. The present study was carried out by the myco-synthesis of silver nanoparticles (AgNPs) using entomopathogenic fungi Beauveria bassiana and its mosquitocidal properties against different larval instars of Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus. The synthesized AgNPs were characterized by UV-visible spectroscopy, X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), Particle Size Analyzer (PSA), Transmission Electron Microscope (TEM), and Energy Dispersive X-ray spectroscopy (EDX), respectively. The surface plasmon resonance band was observed at 430 ± 1.5 nm in the UV-spectrum. The XRD spectrum of crystallic AgNPs shows four strong intense peaks at 2θ values of 38.12°, 54.14°, 64.18°, and 77.48° assigned to 111, 200, 220, and 311, respectively. The complex nature of AgNPs was confirmed by an FTIR spectrum with peaks observed at 3205.77, 1653.20, 1383.50, 1071.12, 825.58, 668.85, and 565.17 cm−1 respectively. The average size of synthesized AgNPs was confirmed by PSA (128 nm). TEM images confirmed the AgNPs size about 20.44 to 34.16 nm (spherical shape) and EDX spectral peak was observed between 1.741 to 5.430 keV. The larvicidal efficacy of different concentrations (50, 100, 150, 200, 250, and 300 μg mL−1) of mycosynthesized AgNPs was tested against first, second, third, and fourth larval instars of A. aegypti (LC50 = 34.655, 20.522, 22.621, and 22.536; LC90 = 170.207, 144.763, 120.934, and 198.394 μg mL−1), A. stephensi (LC50 = 45.822, 16.777, 22.873, and 30.787; LC90 = 298.812, 111.038, 142.154, and 193.092 μg mL−1), and C. quinquefasciatus (LC50 = 49.36, 26.946, 13.199, and 1.478; LC90 = 161.554, 134.590, 104.639, and 58.923 μg mL−1) and 100% mortality effect was observed with the AgNPs. The antibacterial property of synthesized nanoparticles was observed by the well diffusion method with multi-drug resistant bacteria such as Escherichia coli and Staphylococcus aureus. The fungal mediated silver nanoparticles are comparatively rapid and less expensive and have broad application to antibacterial therapy in modern medicine. The cytotoxic effects of silver nanoparticles showed IC50 values of 28.8 ± 2.5 μg mL−1 against normal HeLa (cervical) cells, with a 24 h incubation period. The outcome of the study suggests that the B. bassiana synthesized silver nanoparticles would be more appropriate for environmentally safer bio insecticidal agents for controlling A. stephensi and C. quinquefasciatus mosquitoes.

Guillemin, Sophie; Consonni, Vincent; Rapenne, Laetitia; Sarigiannidou, Eirini; Donatini, Fabrice; Bremond, Georges

doi: 10.1039/c6ra04634gpmid: N/A

The luminescence lines related to extended defects and interfaces in polycrystalline ZnO thin films grown by sol–gel process are deeply investigated by combining temperature-dependent photoluminescence and cathodoluminescence imaging with high-resolution transmission electron microscopy. A typical broad emission band is shown in the range of 3.316 to 3.333 eV and mainly consists of two distinct contributions. At high energy, a 3.333 eV line is associated with interfaces (i.e., free surfaces and grain boundaries) and predominates for small ZnO nanoparticles owing to their high density. The intensity ratio of the excitonic to interface-related transitions is low in this first configuration and the 3.333 eV line is characterized by an activation energy of 12.0 ± 1.2 meV and a Huang-Rhys factor of 0.54 ± 0.05 at 12 K. At low energy, a 3.316 eV line is attributed to basal plane stacking faults that are mostly of I1-type and prevail for large ZnO nanoparticles. The 3.316 eV line is characterized by an activation energy of 6.7 ± 0.8 meV and a Huang Rhys constant of 0.87 ± 0.03 at 12 K. Basal plane stacking faults are most likely formed as the coalescence process proceeds with the decomposition and crystallization processes during annealing. As shown by low-temperature monochromatic cathodoluminescence imaging, the luminescence corresponding to the 3.316 eV line is, in this second configuration, limited to some specific area (i.e., large nanoparticles), and the relative intensity ratio of the excitonic to interface-related transitions is increased due to the smaller free surface area and density of grain boundaries.

Liu, Yanhui; Wang, Wenhe; Zhang, Weiwei; Dong, Yanan; Han, Fengjiao; Raza, Muslim; Liu, Luo; Tan, Tianwei; Feng, Yue

doi: 10.1039/c6ra90042apmid: N/A

Correction for ‘Structure of a thermostable methionine adenosyltransferase from Thermus thermophilus HB27 reveals a novel fold of the flexible loop’ by Yanhui Liu et al., RSC Adv., 2016, 6, 41743–41750.

Zhou, Hui; Zhang, Qing-Yong; Lu, Xiao-Bing

doi: 10.1039/c6ra07786bpmid: N/A

A N-heterocyclic carbene copper(i) complex functionalized conjugated microporous polymer (CMP-NHC-CuCl) was synthesized by palladium-catalyzed Sonogashira cross-coupling chemistry. The resulting CMP-NHC-CuCl proved to be a good heterogeneous catalyst in the hydrosilylation of functionalized terminal alkynes with boryldisiloxane to afford (β,β)-(E)-vinyldisiloxane with high stereoselectivity, and the catalyst could be used four times without obvious loss in catalytic activity. Moreover, CMP-NHC-CuCl was also efficient in catalyzing the hydrosilylation of CO2 with triethoxysilane to form silyl formate under mild conditions.

Wang, Xiu; Yang, Chunlei; Yan, Mei; Ge, Shenguang; Yu, Jinghua

doi: 10.1039/c6ra06953cpmid: N/A

In this paper, a novel phenyleneethynylene derivative 4,4′-(2,5-dimethoxy-1,4-phenylene)bis(ethyne-2,1-diyl) dibenzoic acid (p-acid) and its derivative p-acid-Br were synthesized. Infrared spectroscopy (IR), fluorescence (FL) spectroscopy and ultraviolet visible (UV-vis) spectroscopy were applied to characterize p-acid and p-acid-Br. To research the practical applicability, a sample thiourea sensor was constructed using the p-acid-Br label, in which the FL intensity response was proportional to the thiourea concentration in the range of 0.5–1000 nM, with a detection limit of 0.26 nM. Furthermore, the sensor showed high specificity, excellent stability, and good reproducibility. The p-acid-Br-based thiourea sensor can also provide potential application for detection of other organics. The method showed low detection limit, good specificity, high sensitivity and reproducibility. Satisfactory results were obtained for the determination of thiourea in various water samples and fruit juice samples. This work is to open new avenues in the application of the phenyleneethynylene derivative for a sensitive thiourea assay. Hence, the proposed fluorescence sensor could become a promising method for local market.

Anuradha, ; Latham, Kay; Bhosale, Sheshanath V.

doi: 10.1039/c6ra06800fpmid: N/A

This paper reports a highly selective nitrite ion receptor based on an AIE-active tetraphenylethene-bearing amino functionality. In water, the receptor has been shown to be selective for nitrite ion (NO2−) over other anions (NO2−, CH3COO−, NO3−, CO32−, S2O32−, SO42−, HSO3−, and Cl−), with pronounced changes in absorption characteristics i.e. red-shift of ∼30 nm. The visual observation of colour change, shift in absorption, and enhancement of emission, clearly show that this receptor is very selective and sensitive to nitrite ions.

Wang, Chunhua; Hu, Feng; Yang, Kejian; Hu, Tianhui; Wang, Wenzhi; Deng, Rusheng; Jiang, Qibin; Zhang, Hailiang

doi: 10.1039/c6ra03017cpmid: N/A

Nylon 6/sulfonated graphene (NSG) composites were prepared using sulfonated graphene (SG) with strong polar sulfonic acid groups as a precursor by the in situ hydrolytic ring-opening polymerization of ε-caprolactam. SG dissolved in the water and then quickly dispersed in an ε-caprolactam melt with simple stirring in an autoclave. The generated PA6 chains were covalently grafted onto SG sheets by the condensation reaction between the active amino groups at PA6 chain terminals and the sulfonic acid groups on SG sheets. The grafted structure and SG content have a great effect on their properties. Compared with pure nylon 6 (PA6), the mechanical properties of NSG composites can be maintained and even enhanced by the use of an appropriate SG content. Research on crystallization and rheological behaviors indicate that NSG composites have a faster crystallization rate and higher flowability than pure PA6, which are beneficial for the use of rapid molding processes. Moreover, the homogeneous dispersion of SG sheets in NSG composites is conducive to the formation of consecutive thermal conductive paths or networks at a relatively low SG content, which significantly improves the thermal conductivity from 0.203 W m−1 K−1 for pure PA6 to 0.398 W m−1 K−1 for a NSG composite with only 3 wt% SG content. Such NSG composites with a simple preparation process, good mechanical properties, excellent processability and high thermal conductivity provide great promise for wider applications of PA6 materials in thermal conductive systems.