Synthesis of Raspberry-like Nanoparticles via Surface Grafting of Positively Charged Polyelectrolyte Brushes: Colloidal Stability and Surface Properties.

A method to synthesize stable, raspberry-like nanoparticles (NPs), using surface grafting of poly(glycidyl methacrylate) (PGMA) brushes on a polystyrene (PS) core with varying grafting densities, is reported. A two-step functionalization reaction of PGMA epoxide groups comprising an amination step first using ethylene diamine and then followed by a quaternization using glycidyltrimethylammonium chloride generates permanently and positively charged polyelectrolyte brushes, which result in both steric and electrostatic stabilization. The dispersion stability of the brush-bearing NPs is dramatically improved compared to that of the pristine PS core in salt solutions at ambient (25 °C) and elevated temperatures (60 °C).

Probing the Interfacial Properties of Oil-Water Interfaces Decorated with Ionizable, pH Responsive Silica Nanoparticles.

Particle-stabilized emulsions (Pickering emulsions) have recently attracted significant attention in scientific studies and for technological applications. The interest stems from the ease of directly assembling the particles at interfaces and modulating the interfacial properties. In this paper, we demonstrate the formation of stable, practical emulsions leveraging the assembly of ionizable, pH responsive silica nanoparticles, surface-functionalized by a mixture of silanes containing amine/ammonium groups, which renders them positively charged.

Probing the Mechanism of Targeted Delivery of Molecular Surfactants Loaded into Nanoparticles after Their Assembly at Oil-Water Interfaces.

A targeted and controlled delivery of molecular surfactants at oil-water interfaces using the directed assembly of nanoparticles, NPs, is reported. The mechanism of NP assembly at the interface and the release of molecular surfactants is followed by laser scanning confocal microscopy and surface force spectroscopy. The assembly of positively charged polystyrene NPs at the oil-water interface was facilitated by the introduction of carboxylic acid groups in the oil phase (e.

Green Synthesis and Characterization of Silver Nanoparticles with High Antibacterial Activity Using Cell Extracts of Cyanobacterium sp.

In this work, we demonstrated the ability of the cyanobacterium sp. to produce ultra-small silver nanoparticlesin the forms of metallic silver (Ag) and silver oxides (AgO) via a facile green synthetic process. The biological compounds in the cyanobacterial cellular extract acted both as reducing agents for silver ions and functional stabilizing agents for the silver nanoparticles.

Monitoring the Early Stages of Formation of Oil-Water Emulsions Using Flow Cytometry.

Characterization of complex oil emulsions is critical yet challenging both in science and in many industrial applications. Here we demonstrate for the first time the use of flow cytometry as a fast method for characterizing complex, polydisperse oil-water emulsions. Owing to our interest in understanding how the presence of specific ions might affect the properties of oil-water emulsions including size, polydispersity, and complexity, we present a systematic study of oil emulsions in deionized water and various brines of different ionic strength.

Stimuli-Responsive, Hydrolyzable Poly(Vinyl Laurate--vinyl Acetate) Nanoparticle Platform for In Situ Release of Surfactants.

A stimuli-responsive, sub-100 nm nanoparticle (NP) platform with a hydrolyzable ester side chain for in situ generation of surfactants is demonstrated. The NPs were synthesized via copolymerization of vinyl-laurate and vinyl-acetate [-(VL--VA), 3:1 molar ratio] and stabilized with a protective poly(ethylene-glycol) shell. The NPs are ∼55 nm in diameter with a zeta potential of -54 mV.

Green Synthesized Magnetic Nanoparticles as Effective Nanosupport for the Immobilization of Lipase: Application for the Synthesis of Lipophenols.

In this work, hybrid zinc oxide-iron oxide (ZnOFe) magnetic nanoparticles were synthesized employing leaf aqueous extract as a reducing/chelating and capping medium. The resulting magnetic nanoparticles were characterized by basic spectroscopic and microscopic techniques, namely, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier-transform infrared (FTIR) and atomic force microscopy (AFM), exhibiting a spherical shape, average size of 15-17 nm, and a functionalized surface. Lipase from (TLL) was efficiently immobilized on the surface of ZnOFe nanoparticles through physical absorption.

Development of Effective Lipase-Hybrid Nanoflowers Enriched with Carbon and Magnetic Nanomaterials for Biocatalytic Transformations.

In the present study, hybrid nanoflowers (HNFs) based on copper (II) or manganese (II) ions were prepared by a simple method and used as nanosupports for the development of effective nanobiocatalysts through the immobilization of lipase B from . The hybrid nanobiocatalysts were characterized by various techniques including scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), X-ray diffraction (XRD), Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR). The effect of the addition of carbon-based nanomaterials, namely graphene oxide and carbon nanotubes, as well as magnetic nanoparticles such as maghemite, on the structure, catalytic activity, and operational stability of the hybrid nanobiocatalysts was also investigated.

Anisotropic Self-Assembly of Organic-Inorganic Hybrid Microtoroids.

Toroidal structures based on self-assembly of predesigned building blocks are well-established in the literature, but spontaneous self-organization to prepare such structures has not been reported to date. Here, organic-inorganic hybrid microtoroids synthesized by simultaneous coordination-driven assembly of amphiphilic molecules and hydrophilic polymers are reported. Mixing amphiphilic molecules with iron(III) chloride and hydrophilic polymers in water leads, within minutes, to the formation of starlike nanostructures.

Hormonal (Cortical-Gonadotropic Axis) and Physical Changes With Two Years Intense Exercise Training in Elite Young Soccer Players.

Hammami, MA, Ben Abderrahman, A, Hackney, AC, Kebsi, W, Owen, AL, Nebigh, A, Racil, G, Tabka, Z, and Zouhal, H. Hormonal (cortical-gonadotropic axis) and physical changes with two years intense exercise training in elite young soccer players. J Strength Cond Res 31(9): 2388-2397, 2017-The aim of this study was to investigate the effects of 2 soccer-training seasons on physical fitness and hormone concentrations in elite youth soccer players.

Effects of a soccer season on anthropometric characteristics and physical fitness in elite young soccer players.

The aim of this study was to evaluate the effect of a soccer-training season on the anthropometric and performance characteristics of elite youth soccer players. Two groups (age: 14.4 years) participated in this study: (1) 24 soccer players training 8 to 10 hours per week and (2) 26 non-athletic boys used as controls.