Saleh Khamlich

Sageretia thea (Osbeck.) mediated synthesis of zinc oxide nanoparticles and its biological applications

AIM To investigate the physical and biological properties of bioinspired zinc oxide (ZnO) nanoparticles via aqueous leaf extracts of Sageretia thea. EXPERIMENTAL Nanoparticles of size approximately 12.4 nm were extensively characterized. In vitro antimicrobial, cytotoxic, biocompatible and enzyme inhibition assays were performed. RESULTS Significant antimicrobial activities with and without UV illumination are reported. Bioinspired ZnO nanoparticles were found effective against fungal strains. MTT assay was performed to check the leishmanicidal activity against promastigotes (IC50: 6.2 μg/ml) and amastigotes (IC50: 10.87 μg/ml) of Leishmania tropica. Brine shrimp lethality was also indicated by bioinspired ZnO nanoparticles (IC50: 21.29 μg/ml). CONCLUSION Hemocompatible nature of bioinspired nanoparticles was revealed. Furthermore, the antioxidant activities were performed. In addition, significant protein kinase while insignificant alpha amylase inhibition were recorded.

Microwave-assisted synthesis of simonkolleite nanoplatelets on nickel foam-graphene with enhanced surface area for high-performance supercapacitors

Simonkolleite (Zn5(OH)8Cl2·H2O) nanoplatelets has been deposited on nickel foam-supported graphene by using an efficient microwave-assisted hydrothermal method. The three-dimensional (3D) porous microstructure of the as-fabricated nickel foam-graphene/simonkolleite (NiF-G/SimonK) composite is beneficial to electrolyte penetration and ions exchange, whereas graphene provide improved electronic conductivity. Structural and morphological characterizations confirmed the presence of highly crystalline hexagonal-shaped nanoplatelets of simonkolleite. Field emission scanning electron microscope (FE-SEM) of the NiF-G/SimonK composite revealed that the SimonK nanoplatelets were evenly distributed on the surface of NiF-G and interlaced with each other, resulting in a higher specific surface area of 35.69 m(2) g(-1) compared to SimonK deposited directly on NiF 17.2 m(2) g(-1). Electrochemical measurements demonstrated that the NiF-G/SimonK composite exhibit a high specific capacitance of 836 F g(-1) at a current density of 1 A g(-1), and excellent rate capability and cycling stability with capacitance retention of 92% after 5000 charge/discharge cycles.

Rapid microwave-assisted growth of silver nanoparticles on 3D graphene networks for supercapacitor application

Silver nanoparticles (AgNPs) grown on a three dimensional (3d) graphene networks (GNs) has been successfully prepared by an efficient and rapid microwave-assisted growth process to form GNs/AgNPs nanocomposite electrode materials for supercapacitor application. The 3d nature of the used GNs offers a unique architecture, which creates an efficient conduction networks and maximum utilization of space and interface, and acts as a conductive layer for the deposited AgNPs. The electrochemical performances of the fabricated electrode were evaluated by cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) tests. Specifically, the optimal GNs/AgNPs nanocomposite exhibits remarkable performances with a high specific capacitance of 528Fg-1 at a current density of 1Ag-1 and excellent capacitance retention of ∼93% after 3000cycles. Moreover, this microwave-assisted growth strategy of AgNPs is simple and effective, which could be extended to the construction of other three dimensional graphene based metallic composites for energy storage and conversion applications.

Green biosynthesis of ruthenium oxide nanoparticles on nickel foam as electrode material for supercapacitor applications

Ruthenium(IV) oxide (RuO2) nanoparticles were synthesized via Aspalathus linearis natural extract as a reducing/oxidizing agent, as well as a capping compound. RuO2 nanoparticles synthesised via a complete green chemistry process would be beneficial for the development of clean, nontoxic and environmentally friendly bio-synthesis procedures. The deposition of RuO2 nanoparticles on nickel foam (NiF) was carried out to form NiF/RuO2 electrode material. Structural characterization showed the amorphous nature of the biosynthesized RuO2, and demonstrated the characteristic peaks of Ni, while the XPS images exhibited the characteristic shape of the Ru 3d, 3p core level peaks, as well as O 1s of the deposited RuO2 on NiF. The electrochemical investigations of the NiF/RuO2 electrode showed a high specific capacitance of 750 F g−1 at a current density of 10 Ag−1 for our device measured by using a three-electrode configuration. The NiF/RuO2 electrode also demonstrated a high rate capability of ∼97.5% capacitance retention at a current density of 10 Ag−1. These results confirmed that the green biosynthesis of RuO2 on NiF could be a promising method to fabricate supercapacitor electrodes with high electrochemical performance for supercapacitor applications.

Adsorption of cadmium from aqueous solution using Rooibos shoots as adsorbent

The use of Rooibos shoots, a natural adsorbent, for cadmium removal from wastewater is proposed. The effects of initial pH, adsorbent dosage, contact time, and initial concentration were investigated in the batch adsorption mode. The optimum pH was found to be 5.5. Isotherm and kinetic data were modeled; the data fitted best to the Freundlich model, and, kinetically, the adsorption was of pseudo-second order as shown by the high R2 value of 0.9928 along with close agreement between the experimental qe (13.9 mg g−1) and calculated qe (14.24 mg g−1) values. The studied biomass material was found to be effectively used for removal of cadmium from contaminated mine wastewater.

Artemisia herba-alba Asso eco-friendly reduced few-layered graphene oxide nanosheets: structural investigations and physical properties

ABSTRACT Nowadays graphene is universally known as a promising material. Hence, the development of eco-friendly synthesis methods for this material is of great importance. This study reports on the bio-synthesis of graphene by a green chemistry process using Artemisia herba-alba Asso (AHAA) natural extract. Moreover, this work reports on the physical properties, including surface/interface and optical and electrical properties of the obtained graphene sheets. UV–VIS, Raman, XPS spectroscopies and TEM microscopy investigations confirmed the reduction, and the conversion of graphene oxide to few-layered reduced graphene oxide as well as the efficiency of this plant extract compared with several natural extracts and chemical agents. Furthermore, it was found that the optical and electrical properties of graphene can be modulated and controlled via this eco-friendly cost-effective process. Hence, AHAA can be an effective chelating agent to produce graphene sheets. GRAPHICAL ABSTRACT

Biosynthesis of pure hematite phase magnetic iron oxide nanoparticles using floral extracts of Callistemon viminalis (bottlebrush): their physical properties and novel biological applications

Abstract Aqueous floral extracts of Callistemon viminalis were used to synthesize Fe2O3 nanoparticles (IONPs) which were intensively characterized through UV–vis, X-ray diffraction, HR-SEM/HR-TEM, Fourier- transform infrared spectroscopy (FTIR) and energy dispersive X-ray spectroscopy (EDS). Their physical properties were studied in response to different annealing temperatures. It was observed that the increase in the annealing temperature produced small-sized nanoparticles. The nanoparticle size was calculated as 32, 26 and 22 nm for annealing at 300, 400 and 500 °C, respectively. The magnetic nature of the bioinspired IONPs was revealed by superconducting quantum interference device (SQUID). Their antibacterial potential was investigated against nine pathogenic bacterial strains (gram positive and gram negative) using disc diffusion method while their MIC was calculated using broth dilution assay. Bioinspired IONPs were found to be highly effective against HepG2 cells (IC50=20 µg/mL). Moderate antileishmanial activities against the promastigotes and amastigotes cultures are reported. Moderate acetylcholine esterase (AchE), butylcholine esterase (BchE) and α-Glycosidase inhibition are reported. Additional assessment of the biocompatibility was performed using haemolytic activity on the freshly isolated human red blood cells and macrophages. Furthermore, the antioxidant activities, including TAC, DPPH and TRP were also performed. Our results indicate that the biogenic and magnetic Fe2O3 can be used for diverse biomedical applications.

Raspberry-like and other hexagonal close-packed morphologies of P(St-MMA-AA) particles obtained from different emulsifiers for photonic applications.

Abstract A facile one-pot synthesis of Poly(Styrene-methyl-methacrylate-acrylic acid) P(St-MMA-AA) terpolymers by soap seeded emulsion polymerization was examined. Raspberry-like and hexagonal close-packed morphologies were conveniently obtained using Cetyltrimethylammonium bromide (CTAB), Sodium dodecyl sulphate (SDS) and Gum arabic (GA) emulsifiers. The resultant colloidal latex samples were used to fabricate coloured tunable photonic crystals via vertical deposition process. The results showed that the emulsifiers used effectively reduced the polydispersity index (PDI) and zeta potential of the terpolymer samples (Ter-PSDS, Ter-PGA and Ter-PCTAB 0.021, 0.097 and 0.076; –36.20, –35.60 and –32.80, respectively). Thus, the interfacial tension between particles that promote the formation of the stable nanosized photonic crystals is also reduced. The low PDI values are clear indication of monodispersity of the terpolymer samples. Varying the choice of emulsifiers also resulted in changes in the particles sizes as well as the resultant morphologies. The particles diameters of 117.15, 209.20 and 315.00 nm were obtained for Ter-PSDS, Ter-PGA and Ter-PCTAB, respectively. The results showed that Ter-PSDS was the most stable of all terpolymers examined. The fabricated photonic crystals were observed to reflect different wavelengths (Iridescent colours) as the observation angles changed. This could be due to the bandgap resulting from the different morphologies associated with the different emulsifiers. The variation in the colour reflectance with change in the observation angle confirms the photonic potential of the synthesized P(St-MMA-AA) crystals.