Showing papers by "Mikhael Bechelany published in 2020"

Response Surface Methodology Optimization of Mono-dispersed MgO Nanoparticles Fabricated by Ultrasonic-Assisted Sol–Gel Method for Outstanding Antimicrobial and Antibiofilm Activities

Abstract: Magnesium oxide (MgO) nanoparticles are one of the highly significant compounds in construction. The novelty concentrated on using sol–gel technique coupled with ultrasonication for synthesis of MgO nanoparticles to prevent the agglomeration and its effect on the size was investigated. The synthesized samples were characterized by TGA, DSC, XRD, FTIR, SEM, EDX mapping, DLS, and HRTEM. Antimicrobial and antibiofilm activities of MgO nanoparticles were investigated against multidrug-resistant microbes causing-urinary tract infection (UTI). TGA, XRD, and FTIR characterization were used to identify the calcination temperature, characterization peaks, and functional groups of MgO nanoparticles, respectively. DLS technique confirmed the particle size distribution which found to be 21.04 nm. HRTEM and SEM/EDX mapping showed that MgO nanoparticles are pure, spherical and the average particle size is 19.2 nm. MgO nanoparticles showed a promising antimicrobial effect against all UTI-causing pathogens. It showed a prominent antimicrobial capability against Staphylococcus aureus, Escherichia coli and Candida albicans by 19.3 mm, 16.1 mm and 15.2 mm ZOI, respectively. Additionally, they showed improved biofilm inhibition as 95.65%, 84.23%, and 76.85% against C. albicans, E. coli and S. aureus, respectively. Therefore, due to these outstanding properties, this study could give insights for solving serious industrial, pharmaceutical and medical challenges throughout the utilization of new nanoparticle-based approach.

Plant celluloses, hemicelluloses, lignins, and volatile oils for the synthesis of nanoparticles and nanostructured materials

Abstract: A huge variety of plants are harvested worldwide and their different constituents can be converted into a broad range of bionanomaterials. In parallel, much research effort in materials science and engineering is focused on the formation of nanoparticles and nanostructured materials originating from agricultural residues. Cellulose (40–50%), hemicellulose (20–40%), and lignin (20–30%) represent major plant ingredients and many techniques have been described that separate the main plant components for the synthesis of nanocelluloses, nano-hemicelluloses, and nanolignins with divergent and controllable properties. The minor components, such as essential oils, could also be used to produce non-toxic metal and metal oxide nanoparticles with high bioavailability, biocompatibility, and/or bioactivity. This review describes the chemical structure, the physical and chemical properties of plant cell constituents, different techniques for the synthesis of nanocelluloses, nanohemicelluloses, and nanolignins from various lignocellulose sources and agricultural residues, and the extraction of volatile oils from plants as well as their use in metal and metal oxide nanoparticle production and emulsion preparation. Furthermore, details about the formation of activated carbon nanomaterials by thermal treatment of lignocellulose materials, a few examples of mineral extraction from agriculture waste for nanoparticle fabrication, and the emerging applications of plant-based nanomaterials in different fields, such as biotechnology and medicine, environment protection, environmental remediation, or energy production and storage, are also included. This review also briefly discusses the recent developments and challenges of obtaining nanomaterials from plant residues, and the issues surrounding toxicity and regulation.

Coupling cathodic electro-fenton with anodic photo-electrochemical oxidation: A feasibility study on the mineralization of paracetamol

Abstract: A cathodic electro-Fenton (EF) process consisting of thermally treated carbon felt and anodic photoelectrochemical (PEC) oxidation process consisting of bismuth vanadate – bismuth oxyiodide electrodeposited on fluorine doped tin oxide glass (FTO-BiVO4/BiOI) were coupled into a single electrochemical advanced oxidation system for the mineralisation of paracetamol. EF degradation of paracetamol yielded 71 % total organic carbon (TOC) removal after 4 h with a current density of 20 mA cm−2. With the coupled EF/PEC system, the complete removal of paracetamol was achieved within 2 h and a higher mineralisation of 92 % TOC removal after 4 h was recorded with a 10 mA cm−2 current density. The specific energy consumption of the EF/PEC process was about 64 % lower than the energy consumption of EF process alone. The treated aqueous solution exhibited reduced toxicity in comparison with the untreated solution with about 1% inhibition of Vibrio fisheri. This EF/PEC system showed a synergic improvement in performance over EF and PEC.

Towards Electrochemical Water Desalination Techniques: A Review on Capacitive Deionization, Membrane Capacitive Deionization and Flow Capacitive Deionization.

Abstract: Electrochemical water desalination has been a major research area since the 1960s with the development of capacitive deionization technique. For the latter, its modus operandi lies in temporary salt ion adsorption when a simple potential difference (1.0-1.4 V) of about 1.2 V is supplied to the system to temporarily create an electric field that drives the ions to their different polarized poles and subsequently desorb these solvated ions when potential is switched off. Capacitive deionization targets/extracts the solutes instead of the solvent and thus consumes less energy and is highly effective for brackish water. This paper reviews Capacitive Deionization (mechanism of operation, sustainability, optimization processes, and shortcomings) with extension to its counterparts (Membrane Capacitive Deionization and Flow Capacitive Deionization).

Nanostructured boron nitride–based materials: synthesis and applications

Abstract: Nanocomposite materials are widely studied because of their unique design opportunities and properties. They can be classified into three main groups in function of the matrix used: polymer-based, ceramic-based, and metal-based nanocomposites. The nanofiller choice is one of the most important steps because it will improve the nanocomposite properties. This review focuses on boron nitride as nanofiller because of its extraordinary properties: high thermal and chemical stability, good mechanical strength, superior resistance to oxidation, good thermal conductivity, and electrical insulation. The goal of this review is to provide an overview on the synthesis methods to produce boron nitride–based nanocomposites, particularly polymer- and ceramic-based nanocomposites, and on their potential applications in promising fields, such as energy, environment, and health.

Highly-efficient electrochemical label-free immunosensor for the detection of ochratoxin A in coffee samples

Abstract: Ochratoxin A (OTA) is among the most important mycotoxins classified as potential risks to human health and food safety. In this work, a novel label-free electrochemical immunosensor has been proposed for the quantitative detection of OTA, based on a two-step strategy for the fabrication of the immunosensor. This involved coating of a carbon felt (CF) electrode with palladium nanoparticles (PdNPs) using atomic layer deposition (ALD), followed by the grafting of the anti-OTA antibodies onto the nanocomposite structure using a carbodiimide functional group via a cross linkage route. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) have been employed for the characterization of the immunosensor properties. The fabricated BSA/anti-OTA/PdNPs/CF immunosensor showed outstanding electrochemical performance towards the detection of OTA in spiked coffee samples. At the optimal working conditions, the linear detection range of the developed immunosensor was from 0.5−20 ng mL−1 (R2 = 0.996) with a low detection limit of 0.096 ng mL-1, making it applicable to the screening of OTA in food products. In addition, the sensor was highly selective to OTA in the presence of interfering compounds and revealed stability of up to three weeks, opening up prospects for the molecular sensing community and paving a new route for quality control in the food industry.

Boron nitride-based nano-biocomposites: Design by 3D printing for bone tissue engineering

Abstract: Here, we produced a synthetic polymer having adequate biocompatibility, biodegradability, bioresorbability and mechanical properties for bone tissue engineering applications. We used the fused depo...

Photoluminescence Study of Defects in ZnO Coated Polyacrylonitrile Nanofibers

Abstract: Core-shell nanostructures of one-dimensional (1D) polyacrylonitrile (PAN)/zinc oxide (ZnO) were obtained by combining atomic layer deposition (ALD) and electrospinning. Nanofibers with different Zn...

Collagen Based Biomaterials for Tissue Engineering Applications: A Review

Abstract: In the search for biomaterials that exhibit both versatility and compatibility with human-tissues, considerable interest has been shown in collagen-based biomaterial for the repair and replacement of the body tissues such as tendons, skin, vascular grafts, heart valves, dental and bones. Some of the general properties of collagen which makes it an interesting biomaterial are the high mechanical strength of the fibers, low antigenicity, its suitability as a substrate for cell growth, and its tunable stability by chemical or physical cross-linking. Collagen based composites are used in various biomedical applications as collagen shields in ophthalmology, sponges for burns and wounds, mini-pellets and tablets for protein delivery, gel formulation in combination with liposome for sustained drug delivery, as controlling material for transdermal delivery, basic matrices for cell culture systems, coating material of metal implant for bone replacement and 3-D printed matrix for various tissue engineering applications. For an adequate biomedical application of collagen, basic knowledge about collagen structure, hierarchical structural organisation and the processing technology in combination with understanding of the physico-chemical properties is of vital importance.

Comparative Investigation of Activated Carbon Electrode and a Novel Activated Carbon/Graphene Oxide Composite Electrode for an Enhanced Capacitive Deionization

Abstract: Capacitive deionization is an emerging brackish water desalination technology whose principle lies in the utilization of porous electrodes (activated carbon materials) to temporarily store ions. Improving the properties of carbon material used as electrodes have been the focus of recent research, as this is beneficial for overall efficiency of this technology. Herein, we have synthesized a composite of activated carbon/graphene oxide electrodes by using a simple blending process in order to improve the hydrophilic property of activated carbon. Graphene oxide (GO) of different weight ratios was blended with commercial Activated carbon (AC) and out of all the composites, AC/GO-15 (15 wt.% of GO) exhibited the best electrochemical and salt adsorption performance in all operating conditions. The as prepared AC and AC/GO-x (x = 5, 10, 15 and 20 wt.% of GO) were characterized by cyclic voltammetry and their physical properties were also studied. The salt adsorption capacity (SAC) of AC/GO-15 at an operating window of 1.0 V is 5.70 mg/g with an average salt adsorption rate (ASAR) of 0.34 mg/g/min at a 400 mg/L salt initial concentration and has a capacitance of 75 F/g in comparison to AC with 3.74 mg/g of SAC, ASAR of 0.23 mg/g/min and a capacitance of 56 F/g at the same condition. This approach could pave a new way to produce a highly hydrophilic carbon based electrode material in CDI.

Palladium/Carbon Nanofibers by Combining Atomic Layer Deposition and Electrospinning for Organic Pollutant Degradation.

Abstract: As organic dyes are a major source of pollution, it is important to develop novel and efficient heterogeneous catalysts with high activity for their degradation. In this work, two innovative techniques, atomic layer deposition and electrospinning, were used to prepare palladium nanoparticles (Pd NPs) supported on carbon nanofibers (CNFs). The sample morphology was investigated using scanning and transmission electron microscopy. This showed the presence of nanofibers of several micrometers in length and with a mean diameter of 200 nm. Moreover, the size of the highly dispersed Pd NPs was about 7 nm. X-ray photoelectron spectroscopy visually validated the inclusion of metallic Pd. The prepared nano-catalysts were then used to reduce methyl orange (MO) in the presence of sodium borohydride (NaBH4). The Freundlich isotherm model was the most suitable model to explain the adsorption equilibrium for MO onto the Pd/CNF catalysts. Using 5 mL MO dye-solution (0.0305 mM) and 1 mL NaBH4 (0.026 mM), a 98.9% of catalytic activity was achieved in 240 min by 0.01 g of the prepared nano-catalysts Pd/C (0.016 M). Finally, no loss of catalytic activity was observed when such catalysts were used again. These results represent a promising avenue for the degradation of organic pollutants and for heterogeneous catalysis.

Investigation of polymer-derived Si-(B)-C-N ceramic/reduced graphene oxide composite systems as active catalysts towards the hydrogen evolution reaction.

Abstract: Hydrogen Evolution Reaction (HER) is an attractive technology for chemical conversion of energy. Replacement of platinum with inexpensive and stable electrocatalysts remains a major bottleneck hampering large-scale hydrogen production by using clean and renewable energy sources. Here, we report electrocatalytically active and ultra-stable Polymer-Derived Ceramics towards HER. We successfully prepared ultrathin silicon and carbon (Si-C) based ceramic systems supported on electrically conducting 2D reduced graphene oxide (rGO) nanosheets with promising HER activity by varying the nature and the composition of the ceramic with the inclusion of nitrogen, boron and oxygen. Our results suggest that oxygen-enriched Si-B-C-N/rGO composites (O-SiBCN/rGO) display the strongest catalytic activity leading to an onset potential and a Tafel slope of - 340 mV and ~ 120 mV dec-1 respectively. O-SiBCN/rGO electrodes display stability over 170 h with minimal increase of 14% of the overpotential compared to ~ 1700% for commercial platinum nanoparticles. Our study provides new insights on the performance of ceramics as affordable and robust HER catalysts calling for further exploration of the electrocatalytic activity of such unconventional materials.

Morphology, Rheology and Crystallization in Relation to the Viscosity Ratio of Polystyrene/Polypropylene Polymer Blends

Abstract: Microfibrillar and droplet morphology of polypropylene (PP) phase dispersed in polypropylene (PS) was fabricated by using melt-extrusion. This morphology was obtained by introducing isotactic PP (20 wt.%) with different viscosity in the PS matrix (80 wt.%). Furthermore, the rheological properties of the blend investigated as a function of the viscosity ratio K. The variations in blend morphology were related to crystallization, melting properties, and viscoelasticity. The blends with K >> 1 develop a fine morphology with PP microfibrils along the flow direction, while diameters of the dispersed PP droplets gradually increase with lower values of K = 1, or K 1), or matrix (K < 1). The variation in blend properties with microfibrillar morphology can be clearly distinguished from heterogeneous blends containing PP droplets, providing an efficient tool to create a binary blend with unique properties.

Photoluminescence Study of Defects in ZnO-Coated Polyacrylonitrile Nanofibers

Abstract: Core–Shell nanostructures of one-dimensional (1D) polyacrylonitrile (PAN)/zinc oxide (ZnO) were obtained by combining atomic layer deposition (ALD) and electrospinning. Nanofibers with different ZnO thicknesses were synthesized and investigated. The present work offers novel information about 1D ZnO structural defects and activation energies (Eₐ) by performing photoluminescence (PL) measurements. PL measurements of 1D ZnO/PAN samples were investigated from 77 to 273 K (room temperature). By analyzing the obtained data of the emission spectrum, Eₐ and temperature coefficients were calculated. The results let us suggest an approximate model of defects in 1D ZnO/PAN structures. It was observed that optical properties are strongly related to the structural properties of the obtained 1D materials; that is, the calculation of the concentration of defects in the ZnO layer was done by analyzing the optical measurements. These investigations allow prediction of the properties of the materials and open a new roadmap for reliable sensing.

Combining Nanoparticles grown by ALD and MOFs for gas separation and catalysis applications

Abstract: Supported metallic nanoparticles (NPs) are essential for many important chemical processes. In order to implement precisely tuned NPs in miniaturised devices by compatible processes, novel nanoengineering routes must be explored. Atomic layer deposition (ALD), a scalable vapor phase technology typically used for the deposition of thin films, represents a promising new route for the synthesis of supported metallic NPs. Metal-organic frameworks (MOFs) are a new exciting class of crystalline porous materials that have attracted much attention in the recent years. Since the size of their pores can be precisely adjusted, these nanomaterials permit highly selective separation and catalytic processes. The combination of NPs and MOF is an emerging area opening numbers of applications, which still faces considerable challenges, and new routes need to be explored for the synthesis of these NPs/MOF nanocomposites. The aim of this paper is double: First, it aims to briefly present the ALD route and its use for the synthesis of metallic NPs. Second, the combination of ALD-grown NPs and MOFs has been explored for the synthesis of Pd NPs/MOF ZIF-8, and several selected examples were ALD-grown NPs and MOFs have been combined and applied gas separation and catalysis will be presented.

ZnO ALD-Coated Microsphere-Based Sensors for Temperature Measurements.

Abstract: In this paper, the application of a microsphere-based fiber-optic sensor with a 200 nm zinc oxide (ZnO) coating, deposited by the Atomic Layer Deposition (ALD) method, for temperature measurements between 100 and 300 °C, is presented. The main advantage of integrating a fiber-optic microsphere with a sensing device is the possibility of monitoring the integrity of the sensor head in real-time, which allows for higher accuracy during measurements. The study has demonstrated that ZnO ALD-coated microsphere-based sensors can be successfully used for temperature measurements. The sensitivity of the tested device was found to be 103.5 nW/°C when the sensor was coupled with a light source of 1300 nm central wavelength. The measured coefficient R2 of the sensor head was over 0.99, indicating a good fit of the theoretical linear model to the measured experimental data.

Enhancement of Podocyte Attachment on Polyacrylamide Hydrogels with Gelatin-Based Polymers

Abstract: Biological activities of cells such as survival and differentiation processes are mainly maintained by a specific extracellular matrix (ECM). Hydrogels have recently been employed successfully in tissue engineering applications. In particular, scaffolds made of gelatin methacrylate-based hydrogels (GelMA) showed great potential due to their biocompatibility, biofunctionality, and low mechanical strength. The development of a hydrogel having tunable and appropriate mechanical properties as well as chemical and biological cues was the aim of this work. A synthetic and biological hybrid hydrogel was developed to mimic the biological and mechanical properties of native ECM. A combination of gelatin methacrylate and acrylamide (GelMA-AAm)-based hydrogels was studied, and it showed tunable mechanical properties upon changing the polymer concentrations. Different GelMA-AAm samples were prepared and studied by varying the concentrations of GelMA and AAm (AAm2.5% + GelMA3%, AAm5% + GelMA3%, and AAm5% + GelMA5%). The swelling behavior, biodegradability, physicochemical and mechanical properties of GelMA-AAm were also characterized. The results showed a variation of swelling capability and a tunable elasticity ranging from 4.03 to 24.98 kPa depending on polymer concentrations. Moreover, the podocyte cell morphology, cytoskeleton reorganization and differentiation were evaluated as a function of GelMA-AAm mechanical properties. We concluded that the AAm2.5% + GelMA3% hydrogel sample having an elasticity of 4.03 kPa can mimic the native kidney glomerular basement membrane (GBM) elasticity and allow podocyte cell attachment without the functionalization of the gel surface with adhesion proteins compared to synthetic hydrogels (PAAm). This work will further enhance the knowledge of the behavior of podocyte cells to understand their biological properties in both healthy and diseased states.